Gson这个Java类库可以把Java对象转换成JSON，也可以把JSON字符串转换成一个相等的Java对象。Gson支持任意复杂Java对象包括没有源代码的对象。
import com.google.gson.annotations.Expose;
public class User {
@Expose
private Long id;
@Expose
private String name;
@Expose
private User next;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public User getNext() {
return next;
}
public void setNext(User next) {
this.next = next;
}
}
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class Test {
public static void main(String[] args) {
User user = new User();
user.setId(1001L);
user.setName("zhenlging");
User next = new User();
next.setId(1002L);
next.setName("yangyang");
user.setNext(next);
GsonBuilder builder = new GsonBuilder();
//不转换没有@Expose注解的字段
builder.excludeFieldsWithoutExposeAnnotation();
Gson gson = builder.create();
//将对象转换为JSON字符串
String sUserString = gson.toJson(user);
System.out.println(sUserString);
User user2 = gson.fromJson(sUserString, User.class);
System.out.println("USER_ID: " + user2.getId() + " USER_NAME:" + user2.getNext().getName());
}
}
- package com.zhl.gson;
- import java.util.HashMap;
- import java.util.Map;
- import com.google.gson.Gson;
- import com.google.gson.GsonBuilder;
- import com.google.gson.reflect.TypeToken;
- public class MapTest {
- public static void main(String[] args) {
- User user1 = new User();
- user1.setId(1001L);
- user1.setName("zhengling");
- User user2 = new User();
- user2.setId(1002L);
- user2.setName("yangyang");
- Map<String, User> userMap = new HashMap<String,User>();
- userMap.put("user1", user1);
- userMap.put("user2", user2);
- GsonBuilder builder = new GsonBuilder();
- Gson gson = builder.create();
- String sUserMap = gson.toJson(userMap, new TypeToken<Map<String,User>>(){}.getType());
- System.out.println(sUserMap);
- //创建Type,Type属于java.lang.reflect.Type
- //Type type = new TypeToken<Map<String, User>>(){}.getType();
- Map<String,User> userMap2 = gson.fromJson(sUserMap, new TypeToken<Map<String, User>>() {}.getType());
- System.out.println(userMap2.get("user1").getName());
- }
- }