Fastjson2的使用

导入FastJson2依赖

maven如下:

<dependency>
  <groupId>com.alibaba.fastjson2</groupId>
  <artifactId>fastjson2</artifactId>
  <version>2.0.26</version>
</dependency>

需要注意导入的包名为com.alibaba.fastjson2

json对象与json数组的创建

json对象创建

JSONObject info = new JSONObject();
info.put("name", "张三");
info.put("age", "18");
info.put("地理", "70");
info.put("英语", "60");

json数组创建

JSONObject info1 = new JSONObject();
info1.put("name", "张三");
info1.put("age", "18");
JSONObject info2 = new JSONObject();
info2.put("name", "李四");
info2.put("age", "19");

//把上面创建的两个json对象加入到json数组里
JSONArray array = new JSONArray();
array.add(info1);
array.add(info2);

json对象取值与json数组遍历取值

json对象取值

JSONArrayarray=newJSONArray();
array.add("1班");
array.add("2班");
array.add("3班");
JSONObjectschool=newJSONObject();
school.put("schoolName","第一中学");
school.put("teacher","刘梅");

JSONObjectinfo=newJSONObject();
info.put("name","张三");
info.put("age","18");
info.put("gradle",array);
info.put("schoolInfo",school);

//从info中取值
System.out.println(info.getString("name"));//张三
System.out.println(info.getIntValue("age"));//18
System.out.println(info.getJSONArray("gradle"));//["1班","2班","3班"]
System.out.println(info.getJSONObject("schoolInfo"));//{"schoolName":"第一中学","teacher":"刘梅"}

json数组遍历取值

JSONObjectinfo1=newJSONObject();
info1.put("name","张三");
info1.put("age","18");
JSONObjectinfo2=newJSONObject();
info2.put("name","李四");
info2.put("age","19");

JSONArrayarray=newJSONArray();
array.add(info1);
array.add(info2);
//遍历获取json数组中对象的值
for(inti=0;i<array.size();i++){
JSONObjectjson=array.getJSONObject(i);
System.out.println(json.getString("name"));
System.out.println(json.getString("age"));
}

json对象与字符串的转换

json对象与字符串的转换

JSONObjectinfo=newJSONObject();
info.put("name","张三");
info.put("age","18");
info.put("地理","70");
info.put("英语","60");

//JSON对象转字符串
Stringstr=JSON.toJSONString(info);
//JSON字符串转JSON对象
JSONObjectjson=JSONObject.parseObject(str);

json字符串的字节数组转json对象

Stringstr="{\"name\":\"张三\",\"age\":\"18\",\"地理\":\"70\",\"英语\":\"60\"}";

byte[]bytes=str.getBytes();
JSONObjectdata=JSON.parseObject(bytes);

json数组与字符串的转换

Stringtext="[\"张三\",\"李四\",\"王五\"]";
//json字符串转json数组
JSONArraydata=JSON.parseArray(text);
//json数组转json字符串
Stringstr=JSONArray.toJSONString(data);

json字符串转java对象的转换

Student测试类

public class Student {
    public String name;
    public 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 Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

json字符串转java对象的转换

Studentstudent=newStudent("张三",18);

//Student对象转JSON字符串
StringstudentStr=JSON.toJSONString(student);
//JSON字符串转Student对象
Studentdata=JSON.parseObject(studentStr,Student.class);

java对象转byte数组转换

Studentstudent=newStudent("张三",18);

//Student对象转字节数组
byte[]text=JSON.toJSONBytes(student);
//字节数组转Student对象
Studentdata=JSON.parseObject(text,Student.class);

json字符串与Map转换

json字符串转Map

        String str="{\n" +
                "\"gradle\":\"高一\",\n" +
                "\"number\":\"2\",\n" +
                "\"people\":[{\"name\":\"张三\",\"age\":\"15\",\"phone\":\"123456\"},\n" +
                "         {\"name\":\"李四\",\"age\":\"16\",\"phone\":\"78945\"}]\n" +
                "}";

        //json字符串转Map
        Map<String, Object> map = JSONObject.parseObject(str, new TypeReference<Map<String, Object>>() {});
        System.out.println(map.get("gradle").toString());
        System.out.println(map.get("number").toString());
        System.out.println(map.get("people").toString());

Map转json字符串

如果直接使用JSON.toJSONString(map)转换，因为"测试1"的值为null，转换的结果就会是

Map<String,String>map=newHashMap<>();
map.put("测试1",null);
map.put("测试2","hello");

//{"测试2":"hello","测试1":null}
Stringstr=JSON.toJSONString(map,JSONWriter.Feature.WriteMapNullValue);

json数组转List

        String str="{\n" +
                "\"gradle\":\"高一\",\n" +
                "\"number\":\"2\",\n" +
                "\"people\":[{\"name\":\"张三\",\"age\":\"15\",\"phone\":\"123456\"},\n" +
                "         {\"name\":\"李四\",\"age\":\"16\",\"phone\":\"78945\"}]\n" +
                "}";

        JSONObject strJson = JSONObject.parseObject(str);
        //获取people数组
        JSONArray people = strJson.getJSONArray("people");
        //json数组转List
        List<Map> list = people.toJavaList(Map.class);

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