JSON数组转Java List

桃扇骨 2022-07-14 22:22 206阅读 0赞

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][jar]

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][]

[fastjson]: https://github.com/alibaba/fastjson
[JSON-lib]: http://json-lib.sourceforge.net/
[jar]: http://download.csdn.net/detail/baalhuo/9460006
[Doc]: http://json-lib.sourceforge.net/apidocs/net/sf/json/package-summary.html