转：jaxb解析xml为对象例子

原文http://weareold.iteye.com/blog/708543


通过jaxb方式把xml文件映射成bean对象。

1、新建java工程或者web工程都可以。
2、通过精简必须导入jar包
         activation.jar
        jaxb-api-2.0.jar
        jaxb-impl-2.0.1.jar
        jsr173_api-1.0.jar
3、 新建xml文件
    <?xml version="1.0" encoding="UTF-8"?>
    <root>

<template
   start="true"
   ip="127.0.0.1"
   port="3344"
   server="server"
/>
<template ... ... />
    </root>

4、新建bean对象，xml的映射文件。
Vo.java 如下

import javax.xml.bind.annotation.XmlAccessType;  
import javax.xml.bind.annotation.XmlAccessorType;  
import javax.xml.bind.annotation.XmlAttribute;  
import javax.xml.bind.annotation.XmlRootElement;  
import javax.xml.bind.annotation.XmlType;  
  
@XmlAccessorType(XmlAccessType.FIELD)  
@XmlType(name = "", propOrder = {  
})  
@XmlRootElement(name = "[color=red]template[/color]")  
public class Vo {  
  
    @XmlAttribute  
    private String start;  
    @XmlAttribute  
    private String ip;  
    @XmlAttribute  
    private String port;  
    @XmlAttribute  
    private String server;  
      
      
    public String getStart() {  
        return start;  
    }  
    public void setStart(String start) {  
        this.start = start;  
    }  
    public String getIp() {  
        return ip;  
    }  
    public void setIp(String ip) {  
        this.ip = ip;  
    }  
    public String getPort() {  
        return port;  
    }  
    public void setPort(String port) {  
        this.port = port;  
    }  
    public String getServer() {  
        return server;  
    }  
    public void setServer(String server) {  
        this.server = server;  
    }  
}  

该文件对应xml文件中 循环节点 template 元素



Root.java 文件如下
Java代码  收藏代码

import java.util.ArrayList;  
import java.util.List;  
  
import javax.xml.bind.annotation.XmlAccessType;  
import javax.xml.bind.annotation.XmlAccessorType;  
import javax.xml.bind.annotation.XmlRootElement;  
import javax.xml.bind.annotation.XmlType;  
  
@XmlAccessorType(XmlAccessType.FIELD)  
@XmlType(name = "", propOrder = {  
})  
@XmlRootElement(name = "[color=blue]root[/color]")  
public class Root {  
      
    protected List<Vo> [color=red]template[/color];  
      
    public List<Vo> getTemplateList() {  
        if (template == null) {  
            template = new ArrayList<Vo>();  
        }  
        return this.template;  
    }  
}  

注意bean对象与xml映射的关系。



5、 解析xml为bean类
Java代码  收藏代码

public static void gernateConfig() throws Exception{  
        StringBuffer buffer  = null;  
        JAXBContext jaxbContext;  
        try {  
                           //读入xml文件流  
                           InputStream is = Excecute.class.getResourceAsStream(“/conf/config.xml”);  
            BufferedReader in = new BufferedReader(new InputStreamReader(is));  
            buffer = new StringBuffer();  
            String line = "";  
            while ((line = in.readLine()) != null) {  
                buffer.append(line);  
            }  
              
            //加载映射bean类  
            jaxbContext = JAXBContext.newInstance(Root.class);  
                           //创建解析  
            Unmarshaller um = jaxbContext.createUnmarshaller();  
            StreamSource streamSource = new StreamSource(new StringReader(buffer.toString()));  
            Root root = (Root) um.unmarshal(streamSource);   
        } catch (Exception e) {  
            e.printStackTrace();  
            throw new Exception(e.getMessage());  
        }  
    }  

6、 把bean对象生成xml字符串方法
Java代码  收藏代码

public static String gernateConfigXml(Root root) throws Exception {  
        if (root != null) {  
            try {  
                JAXBContext context = JAXBContext.newInstance(Root.class);  
                Marshaller m = context.createMarshaller();  
                m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);  
                Writer writer = new StringWriter();  
                m.marshal(root, writer);  
                try {  
                    String xml = writer.toString();  
                    writer.flush();  
                    writer.close();  
                    return xml;  
                } catch (IOException e) {  
                    return "";  
                }  
            } catch (Exception e) {  
                throw new Exception("失败!");  
            }  
        } else {  
            return null;  
        }  
    }