1.数组转换为json字符串（用JSONArray）
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String array[] = new String[]{"one","two","three"};
JSONArray jsonArray= JSONArray.fromObject(array);
System.out.println(jsonArray);
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结果：["one","two","three"]
2.list转换为json字符串（用JSONArray）
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List list = new ArrayList();
list.add("1");
list.add("2");
list.add("3");
JSONArray jsonArray = JSONArray.fromObject(list);
System.out.println(jsonArray);
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结果：["1","2","3"]
3.Map转换为json字符串（用JSONObject）
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Map map = new HashMap<String,String>();
map.put("name", "junxie");
map.put("age", "23");
map.put("county", "china");
JSONObject jsonObject = JSONObject.fromObject(map);
System.out.println(jsonObject);
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结果：{"county":"china","age":"23","name":"junxie"}
4.普通java对象转为json字符串
user对象：
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public class User {
public String name;
public String age;
public String country;
public User(){}
public User(String name,String age,String country){
this.name = name;
this.age = age;
this.country = country;
}
//省略get和set方法
}
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User user = new User("junxie","23","china");
JSONObject jsonObject = JSONObject.fromObject(user);
System.out.println(jsonObject);
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结果：{"age":"23","country":"china","name":"junxie"}
注意：和map的结果一样的
5.复杂的java对象转为json字符串（对象中包含list和map）
UserScores对象：
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public class UserScores{
private List scores; //list
private String name;
private String age;
private Map scores2; //map
.....//省略get和set方法
}
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List scores = new ArrayList();
scores.add("100");
scores.add("98"); //组装list
Map scores2 = new HashMap<String, Integer>();
scores2.put("chinese", "80");
scores2.put("math", "90"); //组装map
UserScores useScores = new UserScores();
useScores.setAge("23");
useScores.setName("junxie");
useScores.setScores(scores);
useScores.setScores2(scores2);
JSONObject jsonObject = JSONObject.fromObject(useScores);
System.out.println(jsonObject);
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结果：
{"age":"23","name":"junxie","scores":["100","98"],"scores2":{"math":"90","chinese":"80"}}
注意:scores为list的生成结果，scores2为map的生成结果
6.json字符串转为普通对象
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String jsonString = "{age:'23',country:'china',name:'junxie'}";
JSONObject jsonObject = JSONObject.fromObject(jsonString);
User user = (User)JSONObject.toBean(jsonObject,User.class);
System.out.println(user.getName());
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结果：打印的name为 junxie
注意：先生成jsonObject，再调用静态方法JSONObject.toBean(jsonObject, beanClass)
7.json字符串转为复杂对象（对象中含有list，map或者其他对象）
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String jsonList = "{age:'23',name:'junxie',scores:['100','98'],scores2:{math:'90',chinese:'80'}}"; //待解析的json字符串
Map map = new HashMap();
map.put("scores", String.class); //复杂对象list
map.put("scores2", Map.class); //复杂对象map （可以有其他的子对象等）
JSONObject jsonObject = JSONObject.fromObject(jsonList);
UserScores userScores= (UserScores)JSONObject.toBean(jsonObject, UserScores.class, map); //注意该方法中要放入之前建立的map
System.out.println(userScores);
List<String> scores = userScores.getScores();
System.out.println(scores);
Map scores2 = userScores.getScores2();
System.out.println(scores2);
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结果：
UserScores@739495b8
[100, 98]
{math=90, chinese=80}
注意：如果要解析成复杂对象时，应该先建立Map，放入所有的复杂对象类型，最后调用方法
JSONObject.toBean(jsonObject, beanClass, classMap) 该classMap则放入所有复杂对象的map
本文转自布拉君君 51CTO博客，原文链接：http://blog.51cto.com/5148737/1541089，如需转载请自行联系原作者