使用XStream实现Java对象与XML互相转换

XStream简介

XStream是一个Java对象与XML互相转换的工具类库。

官网链接: http://x-stream.github.io/index.html

简单使用

下载页面：http://x-stream.github.io/download.html

使用Maven构建项目的加入以下依赖:

<dependency>
    <groupId>com.thoughtworks.xstream</groupId>
    <artifactId>xstream</artifactId>
    <version>1.4.10</version>
</dependency>

创建Bean：

public class User {

    private String userName;

    private String email;

    public User() {}

     public User(String userName, String email) {
        this.userName = userName;
        this.email = email;
    }

    public String toString() {
        return "User:{userName=" + this.userName + ",email=" + this.email + "}";
    }

    //Getter and Setter...
}

Java对象转XML:

使用xStream.toXML()方法。

public static void main(String[] args) {
    
    User user = new User("lanweihong", "[e-mail]");
    
    //创建解析XML对象
    XStream xStream = new XStream();
    //设置别名, 默认会输出全路径
    xStream.alias("User", User.class);
    //转为xml
    String xml = xStream.toXML(user);
    System.out.println(xml);
}

转换后的xml文本为：

<User>
  <userName>lanweihong</userName>
  <email>[e-mail]</email>
</User>

XML转Java对象

使用xStream.fromXML()方法。

public static void main(String[] args) {
    XStream xStream = new XStream();
    xStream.alias("User", User.class);
    String xml = "<User>\n" +
            "  <userName>lanweihong</userName>\n" +
            "  <email>[e-mail]</email>\n" +
            "</User>";
    //转对象
    User user = (User)xStream.fromXML(xml);
    System.out.println(user.toString());
}

输出文本为:

User:{userName=lanweihong,email=[e-mail]}

使用注解

最基本的注解@XStreamAlias用于设置字段别名；我们将上述例子创建的User对象添加注解改造一下:

@XStreamAlias("user")
public class User {

    @XStreamAlias("username")
    private String userName;

    @XStreamAlias("email")
    
    private String email;

    public User() {}

     public User(String userName, String email) {
        this.userName = userName;
        this.email = email;
    }

    public String toString() {
        return "User:{userName=" + this.userName + ",email=" + this.email + "}";
    }

    //Getter and Setter...
}

XStream默认不会读取这个注解，因为，我们需要声明XStream的注解来源：

public static void main(String[] args) {
    User user = new User("lanweihong", "[e-mail]");
    XStream xStream = new XStream();
    //声明XStream注解来源
    xStream.processAnnotations(User.class);
    String xml = xStream.toXML(user);
    System.out.println(xml);
}

输出文本为：

<user>
  <username>lanweihong</username>
  <email>[e-mail]</email>
</user>

由此可见，生成的xml节点名称已经变为我们使用@XStreamAlias注解的别名。

简单封装为工具类

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;

public class XmlUtils {

    /**
     * XML转对象
     * @param clazz 对象类
     * @param str xml字符串
     * @param <T> T
     * @return
     */
    public static <T> T parseFromXml(Class<T> clazz, String xml) {
        //创建解析XML对象
        XStream xStream = new XStream(new DomDriver());
        //处理注解
        xStream.processAnnotations(clazz);
        @SuppressWarnings("unchecked")
        //将XML字符串转为bean对象
        T t = (T)xStream.fromXML(xml);
        return t;
    }

    /**
     * 对象转xml
     * @param obj 对象
     * @return
     */
    public static String toXml(Object obj) {
        XStream xStream = new XStream(new DomDriver());
        xStream.processAnnotations(obj.getClass());
        return xStream.toXML(obj);
    }

}

原文地址：https://www.lwhweb.com/2017/11/21/xstream-1/