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();
    }
  }
}