jdom学习(4)

Jdom使用详解及实例(4)

接上一节:

2、读取xml文档的例子：

java 代码

import org.jdom.output.*;

import org.jdom.input.*;

import org.jdom.*;

import java.io.*;

import java.util.*;

public class ReadXML{

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

        SAXBuilder builder = new SAXBuilder();

        Document read_doc = builder.build("studentinfo.xml");

        Element stu = read_doc.getRootElement();

        List list = stu.getChildren("student");

        for(int i = 0;i < list.size();i++) {

            Element e = (Element)list.get(i);

            String str_number = e.getChildText("number");

            String str_name = e.getChildText("name");

            String str_age = e.getChildText("age");

            System.out.println("---------STUDENT--------------");

            System.out.println("NUMBER:" + str_number);

            System.out.println("NAME:" + str_name);

            System.out.println("AGE:" + str_age);

            System.out.println("------------------------------");

            System.out.println();

        }

       }

}

3、DTD验证的：

java 代码

public class XMLWithDTD {

  public void validate()  {

   try {

    SAXBuilder builder = new SAXBuilder(true);

    builder.setFeature("http://xml.org/sax/features/validation";,true);

    Document doc = builder.build(new FileReader("author.xml"));

    System.out.println("搞掂");

    XMLOutputter outputter = new XMLOutputter();

    outputter.output(doc, System.out);

   }catch(Exception e) {

    System.out.println(e);

   }

  }

  public static void main(String args[]) {

   new XMLWithDTD().validate();

  }

 }

4、XML Schema验证的：

java 代码

public class XMLWithSchema {

 String xml="test.xml";

 String schema="test-schema.xml";

 public void validate() {

  try {

   SAXBuilder builder = new SAXBuilder(true);

   //指定约束方式为XML schema

   builder.setFeature("http://apache.org/xml/features/validation/schema";,  true);

   //导入schema文件

uilder.setProperty("http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation";,schema);

   Document doc = builder.build(new FileReader(xml));

   System.out.println("搞掂");

   XMLOutputter outputter = new XMLOutputter();

   outputter.output(doc, System.out);

  }catch(Exception e) {

   System.out.println("验证失败:"+e);

  }

 }

}

 上面的程序就指出了要引入的XML Schema文件的位置。

5、Xpath例子：

JDOM的关于XPATH的api在org.jdom.xpath这个包里。这个包下，有一个抽象类XPath.java和实现类JaxenXPath.java， 使用时先用XPath类的静态方法newInstance(String xpath)得到XPath对象，然后调用它的selectNodes(Object context)方法或selectSingleNode(Object context)方法，前者根据xpath语句返回一组节点(List对象)；后者根据一个xpath语句返回符合条件的第一个节点(Object类型)。请看jdom-1.0自带的范例程序：

     它分析在web.xml文件中的注册的servlet的个数及参数个数，并输出角色名。

web.xml文件：

xml 代码

xml version="1.0" encoding="ISO-8859-1"?>
<web-app>
    <servlet>
        <servlet-name>snoop<!---->servlet-name>
        <servlet-class>SnoopServlet<!---->servlet-class>
    <!---->servlet>
    <servlet>
        <servlet-name>file<!---->servlet-name>
        <servlet-class>ViewFile<!---->servlet-class>
        <init-param>
            <param-name>initial<!---->param-name>
            <param-value>1000<!---->param-value>
            <description>
                The initial value for the counter  <!---->
            <!---->description>
        <!---->init-param>
    <!---->servlet>
    <servlet-mapping>
        <servlet-name>mv<!---->servlet-name>
        <url-pattern>*.wm<!---->url-pattern>
    <!---->servlet-mapping>
    <distributed/>
    <security-role>
      <role-name>manager<!---->role-name>
      <role-name>director<!---->role-name>
      <role-name>president<!---->role-name>
    <!---->security-role>
<!---->web-app>

处理程序：

java 代码

import java.io.*;

import java.util.*;

public class XPathReader {

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

        if (args.length != 1) {

            System.err.println("Usage: java XPathReader web.xml");

            return;

        }

        String filename = args[0];//从命令行输入web.xml

        PrintStream out = System.out;

        SAXBuilder builder = new SAXBuilder();

        Document doc = builder.build(new File(filename));//得到Document对象



        // Print servlet information

        XPath servletPath = XPath.newInstance("//servlet");//,选择任意路径下servlet元素

        List servlets = servletPath.selectNodes(doc);//返回所有的servlet元素。

        out.println("This WAR has "+ servlets.size() +" registered servlets:");

        Iterator i = servlets.iterator();

        while (i.hasNext()) {//输出servlet信息

            Element servlet = (Element) i.next();

            out.print("\t" + servlet.getChild("servlet-name")

                                    .getTextTrim() +

                      " for " + servlet.getChild("servlet-class")

                                       .getTextTrim());

            List initParams = servlet.getChildren("init-param");

            out.println(" (it has " + initParams.size() + " init params)");

        }

        // Print security role information

        XPath rolePath = XPath.newInstance("//security-role/role-name/text()");

        List roleNames = rolePath.selectNodes(doc);//得到所有的角色名

        if (roleNames.size() == 0) {

            out.println("This WAR contains no roles");

        } else {

            out.println("This WAR contains " + roleNames.size() + " roles:");

            i = roleNames.iterator();

            while (i.hasNext()) {//输出角色名

                out.println("\t" + ((Text)i.next()).getTextTrim());

            }

        }

    }

}

输出结果:

C:\java>java   XPathReader web.xml

This WAR has 2 registered servlets:

        snoop for SnoopServlet (it has 0 init params)

        file for ViewFile (it has 1 init params)

This WAR contains 3 roles:

        manager

        director

        president

注: 要使用XPath必须导入包:saxpath.jar,jaxen-core.jar,jaxen-jdom.jar!!!!