java读取xml文件并转换成对象，并进行修改

1.首先要写工具类，处理读取和写入xml文件使用的工具。XMLUtil.java
import java.io.FileInputStream;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.StringReader;

import java.io.StringWriter;

import javax.xml.bind.JAXBContext;

import javax.xml.bind.JAXBException;

import javax.xml.bind.Marshaller;

import javax.xml.bind.Unmarshaller;

/**   

 * 封装了XML转换成object，object转换成XML的代码   

 *    

 * @author mscall

 *    

 */  

public class XMLUtil {

    /**   

     * 将对象直接转换成String类型的 XML输出   

     *    

     * @param obj   

     * @return   

     */    

    public static String convertToXml(Object obj) {    

        // 创建输出流    

        StringWriter sw = new StringWriter();    

        try {    

            // 利用jdk中自带的转换类实现    

            JAXBContext context = JAXBContext.newInstance(obj.getClass());    

            Marshaller marshaller = context.createMarshaller();    

            // 格式化xml输出的格式    

            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,    

                    Boolean.TRUE);    

            marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8"); 

            // 将对象转换成输出流形式的xml    

            marshaller.marshal(obj, sw);    

        } catch (JAXBException e) {    

            e.printStackTrace();    

        }    

        return sw.toString();    

    }    

    /**   

     * 将对象根据路径写入指定的xml文件里

     *    

     * @param obj   

     * @param path   

     * @return   

     */    

    public static void convertToXml(Object obj, String path) {    

        try {    

            // 利用jdk中自带的转换类实现    

            JAXBContext context = JAXBContext.newInstance(obj.getClass());    

            Marshaller marshaller = context.createMarshaller();    

            // 格式化xml输出的格式    

            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,    

                    Boolean.TRUE);    

            marshaller.setProperty(Marshaller.JAXB_ENCODING, "GBK");

            // 将对象转换成输出流形式的xml    

            // 创建输出流    

            FileWriter fw = null;    

            try {    

                fw = new FileWriter(path);    

            } catch (IOException e) {    

                e.printStackTrace();    

            }    

            marshaller.marshal(obj, fw);    

        } catch (JAXBException e) {    

            e.printStackTrace();    

        }    

    }    

    /**   

     * 将String类型的xml转换成对象   

     */    

    public static Object convertXmlStrToObject(Class<?> clazz, String xmlStr) {    

        Object xmlObject = null;    

        try {

            JAXBContext context = JAXBContext.newInstance(clazz);    

            // 进行将Xml转成对象的核心接口    

            Unmarshaller unmarshal = context.createUnmarshaller();

            StringReader sr = new StringReader(xmlStr);    

            xmlObject = unmarshal.unmarshal(sr);

        } catch (Exception e) {

            e.printStackTrace();    

        }    

        return xmlObject;    

    }    

    /**   

     * 将file类型的xml转换成对象   

     */    

    public static Object convertXmlFileToObject(Class<?> clazz, String xmlPath) {    

        Object xmlObject = null;    

        try {

            JAXBContext context = JAXBContext.newInstance(clazz);    

            Unmarshaller unmarshaller = context.createUnmarshaller();      

            InputStreamReader isr=new InputStreamReader(new FileInputStream(xmlPath),"GBK");

            xmlObject = unmarshaller.unmarshal(isr);    

        } catch (Exception e) {    

            e.printStackTrace();    

        }    

        return xmlObject;    

    }    

}

2、测试写入

public static void test(){

    Users users = new Users(); 

    User u = new User(); 

    u.setUsername("admin");

    u.setPassword("123"); 

    List<User> lus = new ArrayList<>(); 

    lus.add(u); 

    users.setUserList(lus);

    try {

        XMLUtil.convertToXml(users, "C:/XML/users.xml");

    } catch (Exception e1) {

        e1.printStackTrace();

    }

 }

3、测试读

Users users = (Users) XMLUtil.convertXmlFileToObject(Users.class, "C:/XML/Users.xml");

4、xml文件

<?xml version="1.0" encoding="GBK" standalone="yes"?>

<users>

    <user>

        <username>admin0</username>

        <password>123</password>

    </user>

    <user>

        <username>admin</username>

        <password>123</password>

    </user>

</users>