如何将Java对象转换为JSON

Question

这是一个春季项目。我有一个物品清单：

List<User> userList = new ArrayList<>();
userList.add(new User("user1", "password1"));
userList.add(new User("user2", "password2"));
userList.add(new User("user3", "password3"));
userList.add(new User("user4", "password4"));

如何将列表转换为JSON数组

Answer 1

试试这个：

import java.util.*;
import org.json.simple.*;

// this method converts a list to JSON Array
String jsonStr = JSONArray.toJSONString(userList);

Answer 2

List<User> userList = new ArrayList<>();
userList.add(new User("user1", "password1"));
userList.add(new User("user2", "password2"));
userList.add(new User("user3", "password3"));
userList.add(new User("user4", "password4"));

JSONArray jsonArray = new JSONArray(userList );
System.out.println(jsonArray);

For this you need to import:
import org.json.JSONArray;

Answer 3

尝试以下解决方案：

String json = new Gson().toJson(userList);

以下是Gson的maven依赖项：

<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.6</version>
</dependency>

或者从这里下载lib文件： https://search.maven.org/artifact/com.google.code.gson/gson/2.8.6/jar