<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.5</version>
</dependency>

Gson gson =new Gson();

User user = new User(123,"zy");

String str = gson.toJson(user);

System.out.println(str);

Gson gson1 =new Gson();

Map<Integer, String> map= new HashMap<Integer, String>();

map.put(11, "zy");

map.put(12, "zz");

String str1 = gson1.toJson(map);

System.out.println(str1);

Gson gson =new Gson();

User user = new User(123,"zy");

//將對象轉(zhuǎn)為json字符串

String str = gson.toJson(user);

//再由json字符串轉(zhuǎn)為java對象，通過get方法得到對象里的值

User fromJson = gson.fromJson(str, User.class);

System.out.println(fromJson.getAge()+"......"+fromJson.getName());

Gson gson =new Gson();

Map<Integer, String> map= new HashMap<Integer, String>();

map.put(11, "zy");

map.put(12, "zz");

//將map集合轉(zhuǎn)換為json字符串

String str = gson.toJson(map);

//將json字符串轉(zhuǎn)換為map集合

Type type = new TypeToken<Map<Integer, String>>() {

}.getType();

Map<Integer, String> map1 = gson.fromJson(str, type);

//遍歷map集合

for (Integer key : map1.keySet()) {

System.out.println("key="+key+"\tvalue="+map1.get(key));

}