本文实例讲述了java对xml文件增删改查操作。分享给大家供大家参考，具体如下：
xml文件：
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<?xml version="1.0" encoding="utf-8"?><books> <book> <name>哈里波特</name> <price>10</price> <memo>这是一本很好看的书。</memo> </book> <book id="b02"> <name>三国演义</name> <price>10</price> <memo>四大名著之一。</memo> </book> <book id="b03"> <name>水浒</name> <price>6</price> <memo>四大名著之一。</memo> </book> <book id="b04"> <name>红楼</name> <price>5</price> <memo>四大名著之一。</memo> </book></books> |
增删改查 test.java
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import java.io.file;import java.io.fileoutputstream;import org.w3c.dom.*;import javax.xml.parsers.*;import javax.xml.transform.*;import javax.xml.transform.dom.domsource;import javax.xml.transform.stream.*;import javax.xml.xpath.*;public class test { public static void main(string[] args) { documentbuilderfactory factory = documentbuilderfactory.newinstance(); element thebook = null, theelem = null, root = null; try { factory.setignoringelementcontentwhitespace(true); documentbuilder db = factory.newdocumentbuilder(); document xmldoc = (document) db.parse(new file("test.xml")); root = xmldoc.getdocumentelement(); // --- 新建一本书开始 ---- thebook = xmldoc.createelement("book"); theelem = xmldoc.createelement("name"); theelem.settextcontent("新书"); thebook.appendchild(theelem); theelem = xmldoc.createelement("price"); theelem.settextcontent("20"); thebook.appendchild(theelem); theelem = xmldoc.createelement("memo"); theelem.settextcontent("新书的更好看。"); thebook.appendchild(theelem); root.appendchild(thebook); system.out.println("--- 新建一本书开始 ----"); output(xmldoc); // --- 新建一本书完成 ---- // --- 下面对《哈里波特》做一些修改。 ---- // --- 查询找《哈里波特》---- thebook = (element) selectsinglenode("/books/book[name='哈里波特']", root); system.out.println("--- 查询找《哈里波特》 ----"); output(thebook); // --- 此时修改这本书的价格 ----- thebook.getelementsbytagname("price").item(0).settextcontent("15");// getelementsbytagname返回的是nodelist，所以要跟上item(0)。另外，getelementsbytagname("price")相当于xpath的".//price"。 system.out.println("--- 此时修改这本书的价格 ----"); output(thebook); // --- 另外还想加一个属性id，值为b01 ---- thebook.setattribute("id", "b01"); system.out.println("--- 另外还想加一个属性id，值为b01 ----"); output(thebook); // --- 对《哈里波特》修改完成。 ---- // --- 要用id属性删除《三国演义》这本书 ---- thebook = (element) selectsinglenode("/books/book[@id='b02']", root); system.out.println("--- 要用id属性删除《三国演义》这本书 ----"); output(thebook); thebook.getparentnode().removechild(thebook); system.out.println("--- 删除后的ｘｍｌ ----"); output(xmldoc); // --- 再将所有价格低于10的书删除 ---- nodelist somebooks = selectnodes("/books/book[price<10]", root); system.out.println("--- 再将所有价格低于10的书删除 ---"); system.out.println("--- 符合条件的书有 " + somebooks.getlength() + "本。 ---"); for (int i = 0; i < somebooks.getlength(); i++) { somebooks.item(i).getparentnode().removechild(somebooks.item(i)); } output(xmldoc); savexml("test1_edited.xml", xmldoc); } catch (exception e) { e.printstacktrace(); } } /** * 将node的xml字符串输出到控制台 * * @param node */ public static void output(node node) { transformerfactory transfactory = transformerfactory.newinstance(); try { transformer transformer = transfactory.newtransformer(); transformer.setoutputproperty("encoding", "gb2312"); transformer.setoutputproperty("indent", "yes"); domsource source = new domsource(); source.setnode(node); streamresult result = new streamresult(); result.setoutputstream(system.out); transformer.transform(source, result); } catch (exception e) { e.printstacktrace(); } } /** * 查找节点，并返回第一个符合条件节点 * * @param express * @param source * @return */ public static node selectsinglenode(string express, object source) { node result = null; xpathfactory xpathfactory = xpathfactory.newinstance(); xpath xpath = xpathfactory.newxpath(); try { result = (node) xpath.evaluate(express, source, xpathconstants.node); } catch (xpathexpressionexception e) { e.printstacktrace(); } return result; } /** * 查找节点，返回符合条件的节点集。 * @param express * @param source * @return */ public static nodelist selectnodes(string express, object source) { nodelist result = null; xpathfactory xpathfactory = xpathfactory.newinstance(); xpath xpath = xpathfactory.newxpath(); try { result = (nodelist) xpath.evaluate(express, source, xpathconstants.nodeset); } catch (xpathexpressionexception e) { e.printstacktrace(); } return result; } /** * 将document输出到文件 * @param filename * @param doc */ public static void savexml(string filename, document doc) { transformerfactory transfactory = transformerfactory.newinstance(); try { transformer transformer = transfactory.newtransformer(); transformer.setoutputproperty("indent", "yes"); domsource source = new domsource(); source.setnode(doc); streamresult result = new streamresult(); result.setoutputstream(new fileoutputstream(filename)); transformer.transform(source, result); } catch (exception e) { e.printstacktrace(); } }} |
ps：这里再为大家提供几款关于xml操作的在线工具供大家参考使用：
xml在线压缩/格式化工具：https://tool.tuohang.net/t/xml/
希望本文所述对大家java程序设计有所帮助。
原文链接：https://blog.csdn.net/u013183865/article/details/32165289
