1.系统简要概述
所用的思想是在MVC模式下进行开发,主要涉及到的内容有:JSP、javaBean、Servlet、JDBC、以及前端css、js,从具体实施来看主要涉及到的知识有:对jsp主要内置对象的熟练使用。例如,request请求、response响应、session会话、以及利用cookie来进行免登录,EL表达式,JSTL标签,Filter过滤器,Listener监视器,前端的灵活使用等。
2.系统主要用到的数据库表
admins(管理员)表 管理员相关信息
Books(图书)表 记录图书相关信息
Students(学生)表 记录学生相关信息
Borrows(借书)表 记录借阅相关信息
3.主要功能
此次系统分为两个板块,管理员和用户。管理员主要进行用户和图书的增删改查,用户则进行借还操作。
下面简述两者主要功能及实现方法,具体可见后文详解。
管理员:
增加学生、删除学生、查看学生、添加图书、修改图书、删除图书、查看图书
对学生的增删查,主要是在ManageStudent.Servlet里面进行。另外有专门处理学生的数据库类Student.Dao,首先增加和查看功能,直接利用前端提交的post请求,通过method字段在servlet里执行相对应的方法,将结果最终呈现在jsp页面中。至于删除的功能则是利用前端提交的get请求,将学生信息绑定在服务器前台,在后端通过request获取到相应数据,执行删除的方法。
对图书的增删改查类似以上机制,主要是在ManageBook.Servlet里面进行。同理也有Book.Dao,增删基本同添加学生一致。查看这里涉及到分页查看的机制,分页查看利用limit限制条件,对每次浏览的记录分条处理。通过后端每次传输的页值,将结果存储到session会话中,在jsp页面里,通过获取存储的对象输出到浏览器中。至于修改同查看一样,只不过这里,要将原先数据存到文本框内,需要通过get请求,将绑定的数据存储到会话中,然后重定向要修改的页面,中间借用EL表达式比较简洁。
用户:
查看图书、借书、借阅信息查看、还书、查看个人信息
当用户登录成功后,在左边功能框可查看所有图书信息,也可以查看具体类别的图书,这里主要是在userchoise.Servlet里面执行,当用户点击具体某类图书时,会将图书类别传输到服务器端,在servlet里面通过request获取类别,然后调用Book.Dao里面的方法将结果进行封装,在show.jsp页面里通过获取图书对象进行显示。每条图书信息后面附有借书操作功能,主要在Borrow.servlet里面进行,通过get机制将用户信息和图书信息上传到服务器,在servlet里面获取,然后利用Bean来声名对象,对借阅书籍进行更改,同时通过调用borrow.Dao,对图书信息数量进一步修改。
借阅信息的查看可直接在相应jsp里面,根据用户信息调用相应的Dao方法,来获取借阅书籍信息显示当浏览器上。在借阅信息里面可对图书进行归还操作,主要使用return.Servlet,在前端通过get机制,将学生信息和书籍信息上传到服务器端。在后端通过request获取,然后借用borrow.Dao,里面的方法对书籍数量进一步修改。查看个人信息比较见到,直接通过session会话,将事先绑定好的用户信息,直接读取,显示在相应页面中。
3.1管理员功能
管理员主要管理学生和图书,在其项目里面有managestudent.servlet和managebook.servlet两个主要的servlet类。通过前端提供不同的请求来响应对应servlet里面的方法。
3.11登录
首先是管理员需要登录验证,判断数据库中是否有管理员账号相关信息。此次开发中,管理员账号为事先在数据库中录入,不支持注册和记住密码。管理员登录,需要请求adminlogin.servlet处理登录信息,如下(账号:admin 密码:admin):
图1- 1 管理员登录页面
若输入错误密码,则会提示密码错误重新登录(账号:admin 密码:123456):
图1- 2 管理员登录错误页面
3.12添加学生
添加学生功能,主要涉及到 student.dao(主要对学生进行数据库操纵,jdbc代码),student.bean(封装保存学生的基本信息),managestudent.servlet(用来后端操作控制添加学生信息的功能)以及addstusent.jsp(添加学生信息的前端页面)。添加信息的时候注意每项信息不能为空、以及添加的学生信息原数据库中是否有信息等需要在servlet里面做出判断。核心就是student.dao里面的连接数据库操纵语言,以及managestudent.servlet里面的对信息进行控制封装。如下:
图1-3 addstudent.jsp
3.13查看学生
查看学生功能是将数据库中的所有学生信息,展现在前端页面。这里主要涉及到studentDao、managestudent.servlet、student.javabean、showstudent.jsp等,在这里另外增加了一个分页查看的功能,主要思想就是在数据库里查询的时候将其分割,limit(beginpage,pagesize),然后通过查询的所有记录count/pagesize,得出总共的页数,然后在pageservlet里面,整理,最后输出到前端页面。
3.14删除学生
管理员可以删除选中的学生,主要是利用前端绑定的机制,在get模式下,绑定用户的信息,通过前端传入的值,在后端进行相应的处理,在数据库中进行删除学生。所涉及到的类和前面几乎一致,不再重述。
3.15添加书籍
添加书籍类似添加学生,book.javabean(存有图书信息),managebook.Servlet(图书管理的servlet),以及对应的jsp页面.
3.16查看书籍
管理员可查看所有图书信息。
在show_book.jsp里面同时包含修改和删除图书的功能。两个方法对应不同的链接,跳转到相应的servlet中,在处理更改的时候需要用到重定向方法,将原先存到session中的数据,重定向到一个页面进行修改,同时该页面,要保留原有的信息,可以使用EL表达式来进行处理。
3.2用户端功能
3.2.1登录
用户登录页面同管理员登录页面一致,且在同一个jsp里,分两个form表单完成。在用户登录界面增加了注册、和记住密码的功能。首先看登录功能,用户输入账号和密码,前端将数据提交到后端的userloginServlet来进行处理,通过后端的处理与数据库中的结果作比较。验证登录是否成功,下图为登录成功界面。
在用户进行登录的时候有一个复选框,为记住密码的操作。当用户点击记住密码的时候,下次登录不用在输入账号密码,直接点击登录即可。这是利用cookie的机制,通过创建cookie,将账号信息保存到硬盘中。此次系统设计的cookie时间为三天。具体效果如下:
3.2.2注册
注册功能同管理员添加学生一致,只不过这个注册会跳转到userloginsrvlet里面进行处理。结合数据库往里边添加数据,同时也会对,信息是否填写完整,以及原有数据库里面是否有数据做出判断。
3.2.3查询图书
等用户登录成功后,即可看到左面功能栏里面的功能,最上面的就是查看所有图书功能,接下来的一系列则是根据图书类别进行查看图书,方便用户浏览,快速查找结果。里面的一些显示功能主要是,利用超链接的target,来将查询的结果输出到,showBook.jsp页面上。
3.2.4借阅书籍
每个书籍后面附有借书操作的功能,借阅实现的方法主要是,利用前端绑定机制,将用户的信息,和图书信息整合到一块,后端来进行获取。
当borrowservlet,接收到用户信息和图书信息后,通过studentBean,bookBean以及borrowBean,来对借阅功能进行封装处理,这时需要borrowdao来进行数据库的读写操作。
在这里设置每位用户最大借阅量为10本,所以在servlet里面,做出判断借阅量是否大于最大借阅书籍量。来响应用户是否还能继续借阅。若能借阅的话,则通过后台,处理Bean数据,用户借阅量发生变化,图书量也发生变化。
3.2.5借阅信息查询
借阅信息查询这个页面中,可以显示所有借的图书信息,并且在这个页面附有还书的功能,借阅信息主要是利用BorrowServlet和BorrowDAO里面根据用户信息,来获取当前用户下共计的借阅量。
3.2.6还书
还书对应的则是returnservlet,根据用户信息,以及图书信息,来做出合理的判断,在通过BorrowDao,里面的数据库操作对借书量,图书量数据上做出相应的改变。
3.2.7我的基本信息
在我的基本信息里面可以查看除密码以外的所有信息,包括当前借阅量,可借图书量等。具体实施为通过后台数据库将个人信息展现到页面上。
4.代码部分
4.1 dao类
adminDao
package com.demo.dao; import com.demo.javabean.*; import java.sql.SQLException; public class AdminDAO { DBAccess db ; public boolean valid(String username, String password) { boolean isValid = false; db=new DBAccess(); if(db.createConn()) { try { String sql="select * from admins where admin=? and password=?"; db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, username); db.pre.setString(2, password); db.setRs(db.pre.executeQuery()); if(db.getRs().next()){ isValid=true; } }catch (Exception e) { // TODO: handle exception }finally { db.closeRs(); try { db.pre.close(); } catch (SQLException e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } db.closeConn(); } } return isValid ; } public boolean isExist(String username) { boolean isExist = false; db = new DBAccess(); if(db.createConn()) { try { String sql="select * from admins where admin=?"; db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1,username ); db.setRs(db.pre.executeQuery()); if(db.getRs().next()){ isExist=true; } } catch (Exception e) { // TODO: handle exception } finally { db.closeRs(); if(db.pre!=null){ try { db.pre.close(); } catch (Exception e2) { // TODO: handle exception } } db.closeConn(); } } return isExist; } }
BookDao
package com.demo.dao; import com.demo.javabean.*; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; public class BookDAO { DBAccess db; private Books book; public ArrayListgetAllBooks() throws Exception{ db=new DBAccess(); //db.setSql("SELECT * FROM books"); ArrayList books = new ArrayList (); if(db.createConn()){ //db.query(sql); String sql= "SELECT * FROM books"; db.query(sql); while(db.getRs().next()){ book = this.assemble(db.getRs()); books.add(book); } } db.closeRs(); db.closeStm(); db.closeConn(); return books; } public ArrayList getBooksByCategory(String category) throws Exception{//在这里进行分页判断 ArrayList books = new ArrayList (); DBAccess db=new DBAccess(); java.sql.PreparedStatement pre = null; if(db.createConn()){ //db.query(sql); String sql = "select * from books where category = ? "; pre=db.getConn().prepareStatement(sql); pre.setString(1, category); //pre.setInt(2, (page-1)*Students.PAGE_SIZE); //pre.setInt(3, Students.PAGE_SIZE); db.setRs(pre.executeQuery()); while(db.getRs().next()){ book = this.assemble(db.getRs()); books.add(book); } } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); int a=books.size(); System.out.println(a); return books; } public void addBook(String name,String author,String intro,String amount,String category) throws Exception{ // boolean flag = false; DBAccess db = new DBAccess(); if(db.createConn()){ String sql = "insert into books(name,author,intro,amount,category) values('"+name+"','"+author+"','"+intro+"','"+amount+"','"+category+"')"; db.update(sql); db.closeStm(); db.closeConn(); } } public boolean delbook(String name)throws Exception{//删除书籍 DBAccess db = new DBAccess(); boolean flag=false; if(db.createConn()){ //db.setSql("delete from books where name = ?"); String sql="delete from books where name = ?"; db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, name); if(db.pre.executeUpdate()>0)flag=true; //String sql = "delete from books where name = '"+name+"'"; //db.update(sql); //db.closeStm(); //db.closeConn(); } db.closeRs(); db.closeStm(); db.pre.close(); db.closeConn(); return flag; } public boolean isExist(String name) { boolean isExist = false; DBAccess db = new DBAccess(); if(db.createConn()) { String sql = "select * from books where name='"+name+"'"; db.query(sql); if(db.next()) { isExist = true; } db.closeRs(); db.closeStm(); db.closeConn(); } return isExist; } public boolean updateBook(Books book) throws Exception{//借还更新 主要书籍数量 boolean flag = false; DBAccess db=new DBAccess(); String sql = "UPDATE books SET amount=? WHERE id=?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); //conn = OpenConnection.getConnection(); // ps = conn.prepareStatement(sql_str); pre.setInt(1,book.getAmount()); pre.setInt(2,book.getId()); if(pre.executeUpdate() > 0) flag = true; } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); // this.release(); // OpenConnection.closeConnection(conn); return flag; } public boolean updateBook2(Books book) throws Exception{//修改更新 修改图书信息 boolean flag = false; DBAccess db=new DBAccess(); //db.setSql("UPDATE books SET name=?,author=?,amount=?,category=? where id=?"); if(db.createConn()){ String sql="UPDATE books SET name=?,author=?,amount=?,category=? where id=?"; db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, book.getName()); db.pre.setString(2, book.getAuthor()); db.pre.setInt(3, book.getAmount()); db.pre.setString(4, book.getCategory()); db.pre.setInt(5, book.getId()); if(db.pre.executeUpdate() > 0) flag = true; } db.closeRs(); db.closeStm(); db.pre.close(); db.closeConn(); return flag; } public Books getBookById(int id) throws Exception{ DBAccess db=new DBAccess(); String sql = "SELECT * FROM books WHERE id = ?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); // conn = OpenConnection.getConnection(); // ps = conn.prepareStatement(sql_str); pre.setInt(1,id); db.setRs(pre.executeQuery()); if (db.getRs().next()) book = this.assemble(db.getRs()); } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); //this.release(); // OpenConnection.closeConnection(conn); return book; } public Books assemble(ResultSet rs) throws Exception{ book = new Books(); book.setId(rs.getInt("id")); book.setName(rs.getString("name")); book.setAuthor(rs.getString("author")); book.setIntro(rs.getString("intro")); book.setAmount(rs.getInt("amount")); book.setCategory(rs.getString("category")); return book; } public ArrayList findAll(Integer page){//分页查询信息 DBAccess db=new DBAccess(); ArrayList list=new ArrayList (); try { if(db.createConn()){ String sql="select * from books limit ?,? "; db.pre=db.getConn().prepareStatement(sql); db.pre.setInt(1, (page-1)*Students.PAGE_SIZE); db.pre.setInt(2, Students.PAGE_SIZE); db.setRs(db.pre.executeQuery()); while(db.getRs().next()){ Books book=new Books(); book.setId(db.getRs().getInt("id")); book.setName(db.getRs().getString("name")); book.setAuthor(db.getRs().getString("author")); book.setCategory(db.getRs().getString("category")); book.setAmount(db.getRs().getInt("amount")); list.add(book); } db.closeRs(); db.pre.close(); db.closeConn(); } } catch( SQLException e) { e.printStackTrace(); } return list; } public ArrayList getBooksByCategory(String category,Integer page) throws Exception{//在这里进行分页判断(学生端) ArrayList books = new ArrayList (); DBAccess db=new DBAccess(); java.sql.PreparedStatement pre = null; if(db.createConn()){ //db.query(sql); String sql = "select * from books where category = ? limit ?,?"; pre=db.getConn().prepareStatement(sql); pre.setString(1, category); pre.setInt(2, (page-1)*Students.PAGE_SIZE); pre.setInt(3, Students.PAGE_SIZE); db.setRs(pre.executeQuery()); while(db.getRs().next()){ book = this.assemble(db.getRs()); books.add(book); } } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); int a=books.size(); System.out.println(a); return books; } public int countPage(String singal){//查询记录总数 DBAccess db=new DBAccess(); int count=0; try { if(db.createConn()){ String sql; if(!"1".equals(singal)){ sql="select count(*) from books where category=?"; db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, singal); db.setRs(db.pre.executeQuery()); } else { sql="select count(*) from books"; db.pre=db.getConn().prepareStatement(sql); db.setRs(db.pre.executeQuery()); } if(db.getRs().next()){ count=db.getRs().getInt(1); } } } catch( SQLException e) { e.printStackTrace(); } finally { db.closeRs(); try { if(db.pre!=null){ db.pre.close(); } } catch (Exception e2) { // TODO: handle exception } db.closeConn(); } return count; } }
BorrowDao
package com.demo.dao; import com.demo.javabean.*; import java.sql.ResultSet; import java.util.ArrayList; import com.demo.javabean.DBAccess; public class BorrowDAO { private Borrows borrow = null; public ArrayListgetAllBorrows() throws Exception{ DBAccess db=new DBAccess(); java.sql.PreparedStatement pre=null; String sql = "SELECT * FROM borrows"; ArrayList borrows = new ArrayList (); //conn = OpenConnection.getConnection(); // ps = conn.prepareStatement(sql_str); //rs = ps.executeQuery(); if(db.createConn()){ pre=db.getConn().prepareStatement(sql); db.setRs(pre.executeQuery()); //db.query(sql); while(db.getRs().next()) { borrow = this.assemble(db.getRs()); borrows.add(borrow); } } //this.release(); db.closeRs(); db.closeStm(); db.closeConn(); // OpenConnection.closeConnection(conn); return borrows; } public ArrayList getBorrowsBySId(int s_id) throws Exception{ ArrayList borrows = new ArrayList (); DBAccess db=new DBAccess(); java.sql.PreparedStatement pre=null; String sql = "SELECT * FROM borrows WHERE s_id = ?"; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); pre.setInt(1, s_id); db.setRs(pre.executeQuery()); while (db.getRs().next()){ borrow = this.assemble(db.getRs()); borrows.add(borrow); } } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); return borrows; } public boolean addBorrows(Borrows borrow) throws Exception{ boolean flag = false; DBAccess db=new DBAccess(); java.sql.PreparedStatement pre=null; String sql = "INSERT INTO borrows VALUES(?,?,?)"; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); // conn = OpenConnection.getConnection(); // ps = conn.prepareStatement(sql_str); pre.setInt(1,borrow.getS_id()); pre.setInt(2,borrow.getB_id()); pre.setInt(3,borrow.getAmount()); if(pre.executeUpdate() > 0) flag = true; } //this.release(); db.closeRs(); pre.close(); db.closeConn(); //OpenConnection.closeConnection(conn); return flag; } public boolean deleteBorrow(Borrows borrow) throws Exception{ boolean flag = false; DBAccess db=new DBAccess(); java.sql.PreparedStatement pre=null; String sql = "DELETE FROM borrows WHERE s_id = ? AND b_id = ? AND amount = ?"; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); //conn = OpenConnection.getConnection(); //ps =conn.prepareStatement(sql_str); pre.setInt(1,borrow.getS_id()); pre.setInt(2,borrow.getB_id()); pre.setInt(3,borrow.getAmount()); if(pre.executeUpdate() > 0) flag = true; } return flag; } public Borrows getBorrowById(int s_id, int b_id) throws Exception{ DBAccess db=new DBAccess(); String sql = "SELECT * FROM borrows WHERE s_id = ? AND b_id = ?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); //conn = OpenConnection.getConnection(); //ps = conn.prepareStatement(sql_str); pre.setInt(1,s_id); pre.setInt(2,b_id); //rs = ps.executeQuery(); db.setRs(pre.executeQuery()); if(db.getRs().next()) borrow = this.assemble(db.getRs()); } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); // this.release(); // OpenConnection.closeConnection(conn); return borrow; } public boolean updateBorrow(Borrows borrow) throws Exception{ boolean flag = false; DBAccess db=new DBAccess(); String sql = "UPDATE borrows SET amount = ? WHERE s_id = ? AND b_id = ?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); //conn = OpenConnection.getConnection(); // ps = conn.prepareStatement(sql_str); pre.setInt(1,borrow.getAmount()); pre.setInt(2,borrow.getS_id()); pre.setInt(3,borrow.getB_id()); if(pre.executeUpdate() > 0) flag = true; } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); //this.release(); //OpenConnection.closeConnection(conn); return flag; } public Borrows assemble(ResultSet rs) throws Exception{ borrow = new Borrows(); borrow.setS_id(rs.getInt("s_id")); borrow.setB_id(rs.getInt("b_id")); borrow.setAmount(rs.getInt("amount")); return borrow; } }
studentDao
package com.demo.dao; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import com.demo.javabean.*; /** *@author:FQX *@version:2022年3月28日下午7:43:34 *类说明 */ public class StudentDAO { DBAccess db; public boolean valid(String username, String password) { boolean isValid = false; //DBAccess db = new DBAccess(); db = new DBAccess(); if(db.createConn()) { //String sql = "select * from students where user='"+username+"' and password='"+password+"'"; //db.setSql("select * from students where user='"+username+"' and password='"+password+"'"); String sql="select * from students where user= ? and password= ?"; try { //这里引用prepareStatement是为了防止SQL注入 db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, username); db.pre.setString(2, password); db.setRs(db.pre.executeQuery()); if(db.getRs().next()){ isValid=true; } } catch (SQLException e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } finally { db.closeRs(); if(db.pre!=null) try { db.pre.close(); } catch (SQLException e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } db.closeConn(); } //db.query(sql); // db.query(db.getSql()); // if(db.next()) { // isValid = true; // } // db.closeRs(); // db.closeStm(); // db.closeConn(); } return isValid ; } public boolean isExist(String username) { boolean isExist = false; db = new DBAccess(); if(db.createConn()) { //String sql = "select * from students where user='"+username+"'"; //db.setSql("select * from students where user='"+username+"'"); String sql="select * from students where user=?"; try { db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, username); db.setRs(db.pre.executeQuery()); if(db.getRs().next()){ isExist=true; } } catch (SQLException e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } finally { db.closeRs(); if(db.pre!=null){ try { db.pre.close(); } catch (Exception e2) { // TODO: handle exception } db.closeConn(); } } //db.query(sql); // db.query(db.getSql()); // if(db.next()) { // isExist = true; // } // db.closeRs(); // db.closeStm(); // db.closeConn(); } return isExist; } public boolean add(Students student) throws Exception{//添加 boolean flag = false; db=new DBAccess(); String sql = "INSERT INTO students(user,password,department,grade,classes,email,amount) VALUES(?,?,?,?,?,?,?)"; if(db.createConn()){ db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1,student.getUser()); db. pre.setString(2,student.getPassword()); db.pre.setString(3,student.getDepartment()); db.pre.setString(4,student.getGrade()); db. pre.setString(5,student.getClasses()); db.pre.setString(6,student.getEmail()); db.pre.setInt(7,student.getAmount()); if(db.pre.executeUpdate() > 0) flag = true; } db.closeRs(); db.closeStm(); db.pre.close(); db.closeConn(); return flag; } public void del(String usename){//删除 DBAccess db = new DBAccess(); if(db.createConn()) { String sql = "delete from students where user = '"+usename+"'"; db.update(sql); db.closeStm(); db.closeConn(); } } private Students student = null; public ArrayListgetAllStudents() throws Exception{ DBAccess db = new DBAccess(); ArrayList students = new ArrayList (); String sql = "SELECT * FROM students"; if(db.createConn()){ db.query(sql); while(db.getRs().next()){ student = this.assemble(db.getRs()); students.add(student); } db.closeStm(); db.closeRs(); db.closeConn(); } return students; } public Students assemble(ResultSet rs) throws Exception{ student = new Students(); student.setId(rs.getInt("id")); student.setUser(rs.getString("user")); student.setPassword(rs.getString("password")); student.setDepartment(rs.getString("department")); student.setGrade(rs.getString("grade")); student.setClasses(rs.getString("classes")); student.setEmail(rs.getString("email")); student.setAmount(rs.getInt("amount")); return student; } public boolean delStudentByName(String user) throws Exception{//删除 DBAccess db=new DBAccess(); boolean flag = false; String sql="DELETE FROM students WHERE user = ?"; if(db.createConn()){ db.pre=db.getConn().prepareStatement(sql); db.pre.setString(1, user); if(db.pre.executeUpdate()>0)flag=true; } db.closeConn(); db.closeStm(); db.pre.close(); db.closeRs(); return flag; } public Students getStudentById(int id) throws Exception{ DBAccess db=new DBAccess(); String sql = "SELECT * FROM students WHERE id = ?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); pre.setInt(1, id); db.setRs(pre.executeQuery()); //conn = OpenConnection.getConnection(); //ps = conn.prepareStatement(sql_str); //ps.setInt(1,id); // rs = ps.executeQuery(); if (db.getRs().next()) student = this.assemble(db.getRs()); } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); //this.release(); //OpenConnection.closeConnection(conn); return student; } public boolean updateStudent(Students student) throws Exception{ boolean flag = false; DBAccess db=new DBAccess(); String sql = "update students set amount = ? where id = ?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); //conn = OpenConnection.getConnection(); // ps = conn.prepareStatement(sql_str); pre.setInt(1,student.getAmount()); pre.setInt(2,student.getId()); if(pre.executeUpdate() > 0) flag = true; } //this.release(); //OpenConnection.closeConnection(conn); db.closeRs(); pre.close(); db.closeStm(); db.closeConn(); return flag; } public Students getStudentByName(String name) throws Exception{ DBAccess db=new DBAccess(); String sql = "SELECT * FROM students WHERE user = ?"; java.sql.PreparedStatement pre=null; if(db.createConn()){ pre=db.getConn().prepareStatement(sql); pre.setString(1, name); db.setRs(pre.executeQuery()); // conn = OpenConnection.getConnection(); //ps = conn.prepareStatement(sql_str); //ps.setString(1,name); // rs = ps.executeQuery(); if(db.getRs().next()) student = this.assemble(db.getRs()); } db.closeRs(); db.closeStm(); pre.close(); db.closeConn(); //this.release(); // OpenConnection.closeConnection(conn); return student; } public ArrayList findAll(Integer page){//分页查询信息 DBAccess db=new DBAccess(); ArrayList list=new ArrayList (); try { if(db.createConn()){ String sql="select * from students limit ?,? "; db.pre=db.getConn().prepareStatement(sql); db.pre.setInt(1, (page-1)*Students.PAGE_SIZE); db.pre.setInt(2, Students.PAGE_SIZE); db.setRs(db.pre.executeQuery()); while(db.getRs().next()){ Students stu=new Students(); stu.setUser(db.getRs().getString("user")); stu.setPassword(db.getRs().getString("password")); stu.setDepartment(db.getRs().getString("department")); stu.setGrade(db.getRs().getString("grade")); stu.setClasses(db.getRs().getString("classes")); stu.setEmail(db.getRs().getString("email")); stu.setAmount(db.getRs().getInt("amount")); list.add(stu); } db.closeRs(); db.pre.close(); db.closeConn(); } } catch( SQLException e) { e.printStackTrace(); } return list; } public int countPage(){//查询记录总数 DBAccess db=new DBAccess(); int count=0; try { if(db.createConn()){ String sql="select count(*) from students "; db.pre=db.getConn().prepareStatement(sql); db.setRs(db.pre.executeQuery()); if(db.getRs().next()){ count=db.getRs().getInt(1); } } } catch( SQLException e) { e.printStackTrace(); } finally { db.closeRs(); try { if(db.pre!=null){ db.pre.close(); } } catch (Exception e2) { // TODO: handle exception } db.closeConn(); } return count; } }
4.2 Servlet类
userlojinServlet
package com.demo.servlet; import com.demo.dao.AdminDAO; import com.demo.dao.StudentDAO; import com.demo.javabean.*; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.*; import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.sql.SQLException; public class UserLoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String method = (String)request.getParameter("method"); if(method==null) { PrintWriter out = response.getWriter(); out.println("invalid request!"); } else if(method.equals("login")) { try { Login(request, response); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } } else if(method.equals("register")) { try { Register(request, response); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } } else if(method.equals("logout")){ Logout(request,response); } } //用户登录 protected void Login(HttpServletRequest request, HttpServletResponse response) throws Exception { //request.setCharacterEncoding("utf-8"); //response.setCharacterEncoding("utf-8"); //response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); String a_user = request.getParameter("user"); String a_password = request.getParameter("password"); System.out.println(a_user); String rem=request.getParameter("remember"); HttpSession session = request.getSession(); StudentDAO a_dao=new StudentDAO(); if ("".equals(a_user) ||"".equals(a_password)) { //System.out.println("登录失败,账号或密码不能为空!"); //response.sendRedirect("login.jsp"); out.println(""); return; } else if(a_dao.isExist(a_user)){ Students student=a_dao.getStudentByName(a_user); session.setAttribute("student", student); if(a_dao.valid(a_user, a_password)){ session.setAttribute("a_user", a_user); user user=new user(); session.setAttribute("user",user); if("1".equals(rem)){ //创建2个Cookie Cookie namecookie=new Cookie("username", a_user); //设置Cookie的有效期为三天 namecookie.setMaxAge(60*60*24*3); Cookie pwdcookie=new Cookie("password", a_password); pwdcookie.setMaxAge(60*60*24*3); response.addCookie(namecookie); response.addCookie(pwdcookie); } //response.sendRedirect(request.getContextPath()+"/user.jsp"); //System.out.println("登录成功!"); out.println(""); } else { //System.out.println("登录失败2,密码错误!"); //response.sendRedirect(request.getContextPath()+"/login.jsp"); out.println(""); } } else { //System.out.println("登录失败3,用户名不存在!"); //response.sendRedirect(request.getContextPath()+"/login.jsp"); out.println(""); } } //用户退出 protected void Logout(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession session = request.getSession(); session.removeAttribute("a_user"); session.removeAttribute("user"); response.sendRedirect("login.jsp"); } //用户注册 protected void Register(HttpServletRequest request, HttpServletResponse response) throws IOException,ServletException { //request.setCharacterEncoding("utf-8"); //response.setCharacterEncoding("utf-8"); //response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); String user = request.getParameter("user"); String password = request.getParameter("password"); String repwd= request.getParameter("repwd"); String department = request.getParameter("department"); String grade = request.getParameter("grade"); String classes = request.getParameter("classes"); String email = request.getParameter("email"); if ("".equals(user) ||"".equals(password) || "".equals(repwd) || !password.equals(repwd)||"".equals(department)||"".equals(grade)||"".equals(classes)||"".equals(email)) { //response.sendRedirect("reg.jsp"); out.println(""); return; }else{ Students student = null; StudentDAO a_dao = new StudentDAO(); boolean isExist =a_dao.isExist(user); if(isExist){ //System.out.println("'此学号已注册过,请重试!"); //response.sendRedirect("reg.jsp"); out.println(""); }else{ student = new Students(); student.setUser(user); student.setPassword(password); student.setDepartment(department); student.setGrade(grade); student.setClasses(classes); student.setEmail(email); student.setAmount(0); try { if(a_dao.add(student)){ student = a_dao.getStudentByName(student.getUser()); request.getSession().setAttribute("student",student); //System.out.println("注册成功,即将跳转到主界面!"); //response.sendRedirect("login.jsp"); out.println(""); return; } } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } } } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //req.setCharacterEncoding("utf-8"); this.doGet(req, resp); } }
adminlojinServlet
package com.demo.servlet; import java.io.*; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import com.demo. dao.AdminDAO; import com.demo.javabean.*; public class AdminLoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String method = (String)req.getParameter("method"); if(method==null) { PrintWriter out = resp.getWriter(); out.println("invalid request!"); } else if(method.equals("login")) { Login(req, resp); } } //管理员登录 protected void Login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //request.setCharacterEncoding("utf-8"); //response.setCharacterEncoding("utf-8"); //response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); String a_user =request.getParameter("a_user"); String a_password = request.getParameter("a_password"); //HttpSession session = request.getSession(); AdminDAO a_dao = new AdminDAO(); //String admin = null; if ( a_user .equals("") ||a_password .equals("")) { //System.out.println("登录失败"); //response.sendRedirect("login.jsp");//重定向 out.println(""); return; } boolean isValid = a_dao.valid(a_user, a_password); if (isValid) { HttpSession session = request.getSession(); session.setAttribute("a_user", a_user); out.println(""); //response.sendRedirect("admin.jsp");//重定向 return; } else { //System.out.println("登录失败"); //response.sendRedirect("login.jsp");//重定向 out.println(""); return; } } // protected void Logout(HttpServletRequest request, // HttpServletResponse response) throws ServletException, IOException { // HttpSession session = request.getSession(); // session.removeAttribute("a_user"); // response.sendRedirect("login.jsp"); // } // @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req,resp); } }
managebookservlet
package com.demo.servlet; import com.demo.dao.BookDAO; import com.demo.javabean.*; import javax.security.auth.message.callback.PrivateKeyCallback.Request; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; public class ManageBookServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // HttpSession session=request.getSession(); // if(session!=null&&session.getAttribute("a_user1")!=null){ // String action = (String)request.getParameter("action"); // if(action==null) { // PrintWriter out = response.getWriter(); // out.println("invalid request!"); // } else if(action.equals("addbook")) { // AddBook(request, response); // } // else if(action.equals("delbook")) { // DelBook(request, response); // } // else if(action.equals("updatebook")) { // UpdateBook(request, response); // } // else if(action.equals("update")) { // Update(request, response); // } // } // else { // response.sendRedirect("login.jsp"); // } String action = (String)request.getParameter("action"); if(action==null) { PrintWriter out = response.getWriter(); out.println("invalid request!"); } else if(action.equals("addbook")) { AddBook(request, response); } else if(action.equals("delbook")) { DelBook(request, response); } else if(action.equals("updatebook")) { UpdateBook(request, response); } else if(action.equals("update")) { Update(request, response); } } //更新图书 private void Update(HttpServletRequest req, HttpServletResponse resp) throws ServletException,IOException{ // TODO 自动生成的方法存根 //req.setCharacterEncoding("utf-8"); //resp.setCharacterEncoding("utf-8"); //resp.setContentType("text/html;charset=utf-8"); Integer sid = Integer.parseInt(req.getParameter("sid")); BookDAO b_dao=new BookDAO(); String page=""; try { Books book=b_dao.getBookById(sid); req.setAttribute("book", book); req.getRequestDispatcher("admin/update_book.jsp").forward(req, resp); } catch (Exception e) { //page="error.jsp"; //TODO 自动生成的 catch 块 e.printStackTrace(); } // finally{ // page="admin/update_book.jsp"; // } // req.getRequestDispatcher(page).forward(req, resp); } private void UpdateBook(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException {//修改图书信息 // TODO 自动生成的方法存根 //req.setCharacterEncoding("utf-8"); //resp.setCharacterEncoding("utf-8"); //resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); String sid=req.getParameter("sid"); String name=req.getParameter("name"); String author=req.getParameter("author"); String amount = req.getParameter("amount"); String category = req.getParameter("category"); BookDAO b_dao=new BookDAO(); Books book=new Books(); if(name != "" && author != "" && amount != "" && category != ""){ book.setName(name); book.setAuthor(author); book.setAmount(Integer.parseInt(amount)); book.setCategory(category); book.setId(Integer.parseInt(sid)); try { if(b_dao.updateBook2(book)){ //System.out.println("修改书籍成功!"); //resp.sendRedirect("PageServlet.do?method=showBook"); out.println(""); return; } else //System.out.println("修改书籍失败!内容不能为空"); out.println(""); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } }else //System.out.println("修改书籍失败!"); //resp.sendRedirect(""); out.println(""); } //删除图书 private void DelBook(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException { // TODO 自动生成的方法存根 //request.setCharacterEncoding("utf-8"); //response.setCharacterEncoding("utf-8"); //response.setContentType("text/html;charset=utf-8"); PrintWriter out=response.getWriter(); String name=request.getParameter("name"); BookDAO b_dao = new BookDAO(); if(name!=null){ try { if(b_dao.delbook(name)){ //System.out.println("删除书籍成功!"); //response.sendRedirect("PageServlet.do?method=showBook"); //return; out.println(""); return; } else //System.out.println("删除书籍失败!"); //response.sendRedirect("admin/del_book.jsp"); out.println(""); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } } else{ //System.out.println("删除图书失败!无此图书"); //response.sendRedirect("admin/del_book.jsp"); out.println(""); } } //添加图书 private void AddBook(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException { // TODO 自动生成的方法存根 //req.setCharacterEncoding("utf-8"); //resp.setCharacterEncoding("utf-8"); //resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); String name = req.getParameter("name"); String author = req.getParameter("author"); String amount = req.getParameter("amount"); String category = req.getParameter("category"); String intro="暂未介绍"; BookDAO b_dao = new BookDAO(); Books book = null; if(name != "" && author != "" && amount != "" && category != ""){ book = new Books(); book.setName(name); book.setAuthor(author); book.setIntro("暂未介绍"); book.setAmount(Integer.parseInt(amount)); book.setCategory(category); //PrintWriter out = resp.getWriter(); try { b_dao.addBook(name, author, intro, amount, category); //System.out.println("添加书籍成功!"); //resp.sendRedirect("admin/reg_book.jsp"); out.println(""); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } }else{ //System.out.println("添加书籍失败!其他原因"); //resp.sendRedirect("admin/reg_book.jsp"); out.println(""); } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //req.setCharacterEncoding("utf-8"); doGet(req,resp); } }
managestudentservlet
package com.demo.servlet; import com.demo.dao.StudentDAO; import com.demo.javabean.*; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; import java.io.PrintWriter; public class ManageStudentServlet extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // HttpSession session=request.getSession(); // if(session!=null&&session.getAttribute("a_user1")!=null){ // String action = (String)request.getParameter("action"); // if(action==null) { // PrintWriter out = response.getWriter(); // out.println("invalid request!"); // } else if(action.equals("addstudent")) { // AddStudent(request, response); // } // else if(action.equals("delstudent")) { // DelStudent(request, response); // } // else if(action.equals("showstudent")){ // ShowStudent(request,response); // } // } // else { // response.sendRedirect("login.jsp"); // } String action = (String)request.getParameter("action"); if(action==null) { PrintWriter out = response.getWriter(); out.println("invalid request!"); } else if(action.equals("addstudent")) { AddStudent(request, response); } else if(action.equals("delstudent")) { DelStudent(request, response); } else if(action.equals("showstudent")){ ShowStudent(request,response); } } private void ShowStudent(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException{ // TODO 自动生成的方法存根 //request.setCharacterEncoding("utf-8"); String user=request.getParameter("user"); StudentDAO studao=new StudentDAO(); Students student=new Students(); try { student=studao.getStudentByName(user); request.setAttribute("student", student); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } request.getRequestDispatcher("admin/show_student.jsp").forward(request, response); } private void DelStudent(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException { req.setCharacterEncoding("utf-8"); resp.setCharacterEncoding("utf-8"); resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); String user=req.getParameter("user"); StudentDAO s_dao = new StudentDAO(); if(user!=null){ System.out.println(user); try { if(s_dao.delStudentByName(user)){ // System.out.println("删除成功!"); //resp.sendRedirect("PageServlet.do?method=showStudent"); out.println(""); return; } else //System.out.println("删除失败!"); //resp.sendRedirect("admin/del_student.jsp"); out.println(""); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } } else{ //System.out.println("删除失败,无此账号!"); //resp.sendRedirect("admin/del_student.jsp"); out.println(""); } } // TODO 自动生成的方法存根 private void AddStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException,IOException { // TODO 自动生成的方法存根 //req.setCharacterEncoding("utf-8"); //resp.setCharacterEncoding("utf-8"); //resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); String user=req.getParameter("user"); String password = req.getParameter("password"); String relpwd=req.getParameter("relpwd"); String department=req.getParameter("department"); String grade = req.getParameter("grade"); String classes=req.getParameter("classes"); String email = req.getParameter("email"); String admin=req.getParameter("admin"); if ("".equals(user) || "".equals(password) ||"".equals(relpwd) || !password.equals(relpwd)||"".equals(department)||"".equals(grade)||"".equals(classes)||"".equals(email)) { //resp.sendRedirect("admin/add_student.jsp"); //System.out.println("信息不全"); out.println(""); return; }else{ StudentDAO a_dao = new StudentDAO(); Students student=new Students(); boolean isExist =a_dao.isExist(user); if(isExist){ //System.out.println("此学号已注册!"); //resp.sendRedirect("admin/add_student.jsp"); out.println(""); } else{ student = new Students(); student.setUser(user); student.setPassword(password); student.setDepartment(department); student.setGrade(grade); student.setClasses(classes);; student.setEmail(email); student.setAmount(0); try { if(a_dao.add(student)){ student = a_dao.getStudentByName(student.getUser()); req.getSession().setAttribute("student",student); //System.out.println("添加成功!"); //resp.sendRedirect(""); out.println(""); return; } } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } } } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //req.setCharacterEncoding("utf-8"); doGet(req,resp); } }
javaBean类
admin
package com.demo.javabean; public class Admins { private int id; //定义管理员的id序号 private String admin; //登录账号 private String password; //密码 private String realname; //真实姓名 private String phone; //电话号码 private String email; //邮箱 private String address; //地址 //获取管理员的id序号 public int getId() { return id; } //设置管理员的id序号 public void setId(int id) { this.id = id; } //获取管理员的账号 public String getAdmin() { return admin; } //设置管理员的账号 public void setAdmin(String admin) { this.admin = admin; } //获取管理员的密码 public String getPassword() { return password; } //设置管理员的密码 public void setPassword(String password) { this.password = password; } //获取管理员的真实姓名 public String getRealname() { return realname; } //设置管理员的真实姓名 public void setRealname(String realname) { this.realname = realname; } //获取管理员的电话 public String getPhone() { return phone; } //设置管理员的电话号码 public void setPhone(String phone) { this.phone = phone; } //获得管理员的邮箱地址 public String getEmail() { return email; } //设置管理员的邮箱地址 public void setEmail(String email) { this.email = email; } //获取管理员的地址 public String getAddress() { return address; } //设置管理员的地址 public void setAddress(String address) { this.address = address; } }
student
package com.demo.javabean; public class Students { public static final int PAGE_SIZE=5; private int id; private String user; private String password; private String department; private String grade; private String classes; private String email; private int amount; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getUser() { return user; } public void setUser(String user) { this.user = user; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getDepartment() { return department; } public void setDepartment(String department) { this.department = department; } public String getGrade() { return grade; } public void setGrade(String grade) { this.grade = grade; } public String getClasses() { return classes; } public void setClasses(String classes) { this.classes = classes; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public int getAmount() { return amount; } public void setAmount(int amount) { this.amount = amount; } }
book
package com.demo.javabean; public class Books { private static final long serialVersionUID = 1L; public static final int PAGE_SIZE=5; private int id; private String name; private String author; private String intro; private int amount; private String category; //取得图书的id序号 public int getId() { return id; } //设置图书的id序号 public void setId(int id) { this.id = id; } //获取图书的名字 public String getName() { return name; } //设置图书的名字 public void setName(String name) { this.name = name; } //获取图书的作者 public String getAuthor() { return author; } //设置图书的作者 public void setAuthor(String author) { this.author = author; } //获取图书的简介 public String getIntro() { return intro; } //设置图书的简介 public void setIntro(String intro) { this.intro = intro; } //获取图书的数量 public int getAmount() { return amount; } //设置图书的数量 public void setAmount(int amount) { this.amount = amount; } //获取图书的类别 public String getCategory() { return category; } //设置图书的类别 public void setCategory(String category) { this.category = category; } }
filter(过滤器类)
loginfilter
package com.demo.filter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class LoginFilter implements Filter {//对登录进行验证过滤 @Override public void destroy() { // TODO 自动生成的方法存根 } @Override public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { // TODO 自动生成的方法存根 HttpServletRequest request=(HttpServletRequest) req; HttpServletResponse response=(HttpServletResponse)resp; HttpSession session=request.getSession(false); if(session!=null&&session.getAttribute("a_user")!=null){ //继续往下走 chain.doFilter(request, response); } else { response.sendRedirect("login.jsp"); } } @Override public void init(FilterConfig arg0) throws ServletException { // TODO 自动生成的方法存根 } }
characterfilter
package com.demo.filter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class CharacterFilter implements Filter {//对字符乱码问题进行过滤 @Override public void destroy() { // TODO 自动生成的方法存根 } @Override public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { // TODO 自动生成的方法存根 HttpServletRequest request=(HttpServletRequest)req; HttpServletResponse response=(HttpServletResponse) resp; request.setCharacterEncoding("utf-8"); response.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); //继续执行 chain.doFilter(request, response); } @Override public void init(FilterConfig arg0) throws ServletException { // TODO 自动生成的方法存根 } }
。。。因代码量较多,就不一一粘贴,有兴趣的友友可以交流。
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原文地址:https://blog.csdn.net/qq_52705208/article/details/125424807