Java IO流相关知识代码解析_Java教程

一、IO流的分类

字符流

Reader
InputStreamReader（节点流）
BufferedReader（处理流）
Writer
OutputStreamWriter（节点流）
BufferedWriter（处理流）
PrintWriter

字节流

InputStream
FileInputStream（节点流）
BufferedInputStream（处理流）
ObjectInputStream（处理流）
PrintStream
OutputStream
FileOutputStream（节点流）
BufferedOutputStream（处理流）
ObjectOutputStream（处理流）

断点处理的流

RandomAccessfile

二、IO流的用法

1、转换流的用法

									FileInputStream in = new FileInputStream(newFile(""));     

									 Readerreader = new InputStreamReader(in);//字节转字符

									 FileOutputStreamout = new FileOutputStream(newFile(""));

									 Writer writer = new OutputStreamWriter(out);//字符转字节

2、对象序列化,对象需要实现Serializable接口

									FileOutputStreamfileOutputStream = new FileOutputStream("C:\\Users\\lx\\Desktop\\Record.txt");

									ObjectOutputStreamobjectOutputStream = new ObjectOutputStream(fileOutputStream);

									objectOutputStream.writeObject(object);//向指定文件写入对象object

									objectOutputStream.close();

									FileInputStreamfileInputStream = new FileInputStream("C:\\Users\\lx\\Desktop\\Record.txt");

									ObjectInputStreamobjectInputStream = new ObjectInputStream(fileInputStream);

									object = objectInputStream.readObject();//读取得到对象object

									fileInputStream . lose();

3、断点的运用

									public class Copy extends Thread{

									    //可以利用多线程实现拷贝  

									    longstart;

									    longend;

									    Filesorce;

									    Filetargetdir;

									    publicCopy() {

									    }

									    publicCopy(longstart,long end, File sorce, File targetdir) {

									        //利用构造方法传递需要拷贝的长度，拷贝开始位置，以及目标文件和源文件

									        super();

									        this.start= start;

									        this.end= end;

									        this.sorce= sorce;

									        this.targetdir= targetdir;

									    }

									    @Override

									       publicvoid run(){

									        try{

									            RandomAccessFilesouceRaf = new RandomAccessFile(sorce,"r");

									            RandomAccessFiletargetRaf = new RandomAccessFile(newFile(targetdir,sorce.getName()),"rw");

									            souceRaf.seek(start);

									            targetRaf.seek(start);

									            intlen= 0;

									            byte[]bs = new byte[1024];

									            longseek;

									            System.out.println(start+"---->"+end+this.getName());

									            while((len= souceRaf.read(bs))!=-1){

									                targetRaf.write(bs, 0, len);

									                seek= souceRaf.getFilePointer();

									                //获取断点位置

									                if(seek== end){

									                    break;

									                }

									            }

									            targetRaf.close();

									            souceRaf.close();

									        }

									        catch (IOException e) {

									            e.printStackTrace();

									        }

									    }

									}

4、字节流的用法

									public class Test_InputStream {

									    //利用字节流获取文本文件内容，但是容易出现问题

									    /*  

									  //可能出现int长度越界

									  public static void main(String[] args) throws IOException {

									    InputStream inputStream = new FileInputStream(new File("C:\\Users\\lx\\Desktop\\test\\33.txt"));

									    byte[] b = new byte[inputStream.available()];  

									    inputStream.read(b);

									    String str = new String(b);

									    System.out.println(str);

									  }

									*/

									    //可能出现乱码    

									    public static void main(String[] args) throws IOException {

									        File file = new File("C:\\Users\\lx\\Desktop\\test\\33.txt");

									        InputStream inputStream = new FileInputStream(file);

									        //统计每次读取的实际长度

									        int len = 0;

									        //声明每次读取1024个字节

									        byte[] b = new byte[2];

									        StringBuffer sBuffer = new StringBuffer();

									        while((len=inputStream.read(b))!=-1){

									            sBuffer.append(new String(b,0,len));

									        }

									        System.out.println(sBuffer.toString());

									    }

									}

									//利用字节流拷贝文件

									public void copy(File sourceFile, File targetDir) {

									    //

									    FileInputStreamfileInputStream = null;

									    FileOutputStreamfileOutputStream = null;

									    fileInputStream= new FileInputStream(sourceFile);

									    FiletargetFile = new File(targetDir,sourceFile.getName());

									    fileOutputStream= new FileOutputStream(targetFile);

									    byte[]b = new byte[1024];

									    intlen = 0;

									    while((len= fileInputStream.read(b)) != -1) {

									        fileOutputStream.write(b, 0, len);

									    }

									}

5、缓存字符流的用法

									publicstatic void main(String[] args) throws IOException {

									    //缓存字符流实现写入文件

									    InputStreamin = System.in;

									    Readerreader = new InputStreamReader(in);

									    BufferedReaderbr = new BufferedReader(reader);

									    BufferedWriterbw = new BufferedWriter(new FileWriter(new File("src/1.txt")));

									    Strings="";

									    while((s=br.readLine())!=null) {

									        bw.write(s);

									        bw.newLine();

									        bw.flush();

									        //字符流千万不要忘了flush!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

									    }

									}