本文使用json-lib jar包实现Json与bean的相互转换

1.将字符串转为JSON

使用JSONObject.fromObject(str)方法即可将字符串转为JSON对象

使用JSONObject.put("attribute","value")可为JSON添加属性

如果需要转为JSON数组，只需使用JSONArray对象提供的方法即可

public static void transformStringTest() {  
      String str = "{" + "\"id\":" + "\"1\"," + "\"name\":" + "\"zhangsan\""  
              + "}";  
      //1.将字符串转为JSON  
      JSONObject jsonObj = JSONObject.fromObject(str);  
      System.out.println(jsonObj.toString());  
      //JSON添加属性  
      jsonObj.put("age", "22");  
      System.out.println(jsonObj.toString());  
      //2.将对象转为数组  
      JSONArray jsonArr = JSONArray.fromObject(jsonObj);  
      System.out.println(jsonArr.toString());  
      //3.将数组添加到JSON对象中  
      JSONObject obj = new JSONObject();  
      obj.put("employees", jsonArr);  
      System.out.println(obj.toString());  
  }  

/* 输出内容 
 * {"id":"1","name":"zhangsan"}  
 * {"id":"1","name":"zhangsan","age":"22"} 
 * [{"id":"1","name":"zhangsan","age":"22"}] 
 * {"employees":[{"id":"1","name":"zhangsan","age":"22"}]} 
 */ 

2.将对象转为JSON

首先创建People类

public class People {  
    private String name;  
  
    private String idcard;  
  
    public People() {  
    }  
  
    public People(String name, String idcard) {  
        this.name = name;  
        this.idcard = idcard;  
    }  
  
    public String getName() {  
        return name;  
    }  
  
    public void setName(String name) {  
        this.name = name;  
    }  
  
    public String getIdcard() {  
        return idcard;  
    }  
  
    public void setIdcard(String idcard) {  
        this.idcard = idcard;  
    }  
  
} 

将对象转为JSON同样使用SONObject.fromObject(obj)方法

如果是一个List,转为JSON时需要使用JSONArray将对象转为JSON数组

public static void transformObjectTest() {  
        People p1 = new People("a", "111111");  
        //1.将对象转为json  
        System.out.println(JSONObject.fromObject(p1));  
        List<People> peopleList = new ArrayList<People>();  
        peopleList.add(p1);  
        //2.将list转为json(需要使用数组JSONArray)  
        JSONArray arr = JSONArray.fromObject(peopleList);  
        System.out.println(arr.toString());  
    }   

/*输出内容 
    * {"idcard":"111111","name":"a"}  
    * [{"idcard":"111111","name":"a"}] 
    */ 

3.JSON转为bean

json转为bean的方法也非常简单，只需使用JSONObject.toBean()方法即可，使用该方法的时候需要传入Bean的class

/** 
     * 将json转换为bean 
     * @param json 
     * @param type 
     * @return 
     */  
    public static <T> Object transformJsonToBean(String json, Class<T> clazz) {  
        JSONObject jsonObject = JSONObject.fromObject(json);  
        return JSONObject.toBean(jsonObject, clazz);  
    }  

4.JSON转为list<bean>集合

由于是集合，所以需要使用JSONArray，JSONArray提供了toCollection方法，使用该方法同样需要传入bean的class

public static <T> Object transformJsonToBeanList(String jsonArr,  
           Class<T> type) {  
       JSONArray jsonArray = JSONArray.fromObject(jsonArr);  
       return JSONArray.toCollection(jsonArray, type);  
   }  

5.xml相关转换

     /**  
     * 描述：json字符串转xml字符串
     */  
    public static void jsonToXML() {  
        System.out.println("json字符串转xml字符串");  
        String jsonStr = "{\"username\":\"张飞\",\"password\":\"123456\",\"age\":\"24\"}";  
        JSONObject jsonObject = JSONObject.fromObject(jsonStr);  
        XMLSerializer xmlSerializer = new XMLSerializer();  
        xmlSerializer.setRootName("user_info");  
        xmlSerializer.setTypeHintsEnabled(false);  
        String xml = xmlSerializer.write(jsonObject);  
        System.out.println("json--->xml \n" + xml);  
    }  
      
    /**  
     * 描述：xml字符串转json字符串
     */  
    public static void xmlToJSON() {  
        System.out.println("xml字符串转json字符串");  
        String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><user_info><password>123456</password><username>宋发元</username></user_info>";  
        XMLSerializer xmlSerializer = new XMLSerializer();  
        JSON json = xmlSerializer.read(xml);  
        System.out.println("xml--->json \n" + json.toString());  
    }  

    /**  
     * 描述：javaBean转xml字符串 
     */  
    public static void javaBeanToXML() {  
        System.out.println("javaBean转xml字符串");  
        UserInfo userInfo = new UserInfo();  
        userInfo.setUsername("songfayuan");  
        userInfo.setPassword("66666");  
        JSONObject jsonObject = JSONObject.fromObject(userInfo);  
        XMLSerializer xmlSerializer = new XMLSerializer();  
        String xml = xmlSerializer.write(jsonObject, "UTF-8");  
        System.out.println("javaBean--->xml \n" + xml);  
    }