Java中Json、String、jsonObject、jsonArray格式之间的互相转换 （Fastjson、Gson、String字符串分隔）

1.org中jackson转换json,springboot中内置jackson

ObjectMapper o=new ObjectMapper();

List<>list=new ArrayList();

String jons=o.writeAsValueString(list);

一、Fastion

使用阿里的fastjson

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.83</version>
</dependency>


import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;

1.json格式的字符串 转JSONObject

public static void myJson(String str) {
    JSONObject obj = JSON.parseObject(str);
 
    // 测试结果
    System.out.println(obj);
}

2.json格式的字符串 转JSONArray

public static void myJson(String str) {        
    JSONArray array = JSON.parseArray(str);
 
    // 测试结果
    for(Object object : array){
        JSONObject obj = (JSONObject)object;
        System.out.println(obj);
    }
}

3.json格式的字符串 转JSONObject、JSONArray

public static void myJson(String str) {
    JSONObject jsonObj = JSON.parseObject(str);
    JSONArray array = JSON.parseArray(jsonObj.getString("name"));
 
    // 测试结果
    for(Object object:array){
        JSONObject obj = (JSONObject)object;
        System.out.println(obj);
    }
}

4.json格式的字符串 转实体类（javaBean）

public class Persion {
	private String name;
	private int age;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	
}


public static void myJson(String str) {
//如果str 是OBJECT 则：
String s = JSONObject.toJSONString(Persion);

//再改对象
    Persion persion = JSON.parseObject(str, new TypeReference<Persion>(){});
 
    // 测试结果
    System.out.println("name:" + persion.getName() + " , " + "age:" + persion.getAge());
}

5.map格式 转JSONObject

public static void myJson(String str) {
    Map<String, Object> map = new HashMap<String, Object>();
    map.put("name","张三");
    map.put("age","18");
 
    JSONObject jsonObj=new JSONObject(map);
 
    // 测试结果
    System.out.println(jsonObj.toString());
}

6.实体类 转json格式的字符串

public static void myJson(Student student) {
    String str = JSONObject.toJSONString(student);
    // 测试结果
    System.out.println(str);
}

7、实体类转实体类

public static void myJson(Student1 student1) {
    String str = JSONObject.toJSONString(student);
	Student2 student2 = JSON.parseObject(str, new TypeReference<Student2>(){});
}

一、提取JsonObject（或Map）中的key-value值

1、获取JsonObject 的key

public void myJson(JSONObject params){
	Map<String, Object> map = params;
	Set<String> keys = map.keySet();
	for (String key : keys) {
		System.out.println(key+"-----"+map.get(key));
	}
}

2.获取JsonObject中的School的key-value值

public void myJson(JSONObject params){
	Map<String, Object> map = params;
	// {"小学":"4","初中":"2","高中":"1"}
	Map<String, String> m1 = (Map<String, String>) map.get("school");
	Set<String> keys = m1.keySet();
	for (String key : keys) {
		System.out.println(key+" ----- "+m1.get(key));
	}
}

二、Gosn

# 需要转jsonStirng的对象

Gson gson= new GsonBuilder().serializeNulls().create();
String jsonObject = gson.toJson(object);

三、String字符串分隔

解决字符串逗号分隔

String namesStr = "山东省,江苏省,广东省,浙江省";
String[] names = namesStr.split(",");
for (int i = 0, len = names.length; i < len; i++) {
	System.out.println(names[i])
}

2.alibaba中fastjson转换成json

 @GetMapping("/test")
    public TbUser testHttpClient(){
        String url="http://localhost:8080/saveUser";
        TbUser user = new TbUser();
        user.setPhone("13568775074");
        user.setUsername("minming");
        user.setPassword("123456");
        //fastjson的JSONObject将Object转json
        String s = JSONObject.toJSONString(user);
        //返回json类型数据
        String result = CloseableHttpCilentsUtils.doPost(url, user, null);
        fastjson的JSONObject将json转Object
        JSONObject  response = JSONObject.parseObject(result);
        TbUser parse = JSONObject.toJavaObject(response, TbUser.class);
        return parse;
}

返回结果：

{
  "password": "123456",
  "phone": "13568775074",
  "username": "minming"