Java对XML文件增删改查操作示例

<?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>

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();

     }

   }

}