JSON数组转Java List

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本文使用alibaba开源项目fastjson与SourceForge开源项目JSON-lib两种方法转换json。

现有json文件user.json如下：

[  {    "userid": "309BCCE3-8525-4D33-9856-5084E24FD96F",    "username": "林梦",    "password": "19bdec7440acd44c669240ed534fc2f6",    "partment": "专案一组",    "tel": "123",    "email": "meng@baal.xyz",    "tag": "专案",    "creater": "",    "time": "2016-10-24T08:10:51.101Z",    "token": ""  },  {    "userid": "FDA8B18B-E6EB-4C80-8A4B-0B2B27AEB7E2",    "username": "汪小雨",    "password": "19bdec7440acd44c669240ed534fc2f6",    "partment": "专案三组",    "tel": "123",    "email": "xiaoyu@baal.xyz",    "tag": "专案",    "creater": "",    "time": "2016-10-24T08:12:28.869Z",    "token": ""  }]

创建数据模型User类，属性如下：

public class User {private String userid;private String username;private String password;private String partment;private String tel;private String email;private String tag;private String creater;private String time;private String token;......}

1、使用fastjson

读取json文件转化为list:

import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStreamReader;import java.util.List;import com.alibaba.fastjson.JSONArray;import com.alibaba.fastjson.JSONObject;public class JsonToList_fastjson {private static final String User_Path = "d:/user.json";private static final String Message_Path = "d:/message.json";public static List<User> getUsers() {String userString = fileToStr(User_Path);List<User> list = JSONObject.parseArray(userString,User.class);return list;}public static String fileToStr(String filepath) {File file = new File(filepath);StringBuffer sb = new StringBuffer();InputStreamReader isr = null;try {isr = new InputStreamReader(new FileInputStream(file), "UTF-8");while (isr.ready()) {sb.append((char) isr.read());}} catch (IOException e) {e.printStackTrace();} finally {try {isr.close();} catch (IOException e) {e.printStackTrace();}}return sb.toString();}public static void main (String [] args) {List<User> listUsers = getUsers();for (User user : listUsers) {System.out.println(user.getEmail());}JSONArray array = (JSONArray) JSONArray.toJSON(listUsers);System.out.println(array);}}

2、使用JSON-lib，相关jar包也可以在这里下载

import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStreamReader;import java.util.List;import net.sf.json.JSONArray;public class JsonToList {private static final String User_Path = "d:/user.json";@SuppressWarnings("unchecked")public static List<User> getUsers() {String userString = fileToStr(User_Path);JSONArray array = JSONArray.fromObject(userString);List<User> list = null;list = (List<User>) JSONArray.toCollection(array, User.class);return list;}public static String fileToStr(String filepath) {File file = new File(filepath);StringBuffer sb = new StringBuffer();InputStreamReader isr = null;try {isr = new InputStreamReader(new FileInputStream(file), "UTF-8");while (isr.ready()) {sb.append((char) isr.read());}} catch (IOException e) {e.printStackTrace();} finally {try {isr.close();} catch (IOException e) {e.printStackTrace();}}return sb.toString();}public static void main(String[] args) {List<User> list = getUsers();for (User user : list) {System.out.println(user.getUsername());}JSONArray array = JSONArray.fromObject(list);System.out.println(array);}}

JSON-lib API ：Doc

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