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 getUsers() {
	String userString = fileToStr(User_Path);
	List 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 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 getUsers() {
	String userString = fileToStr(User_Path);
	JSONArray array = JSONArray.fromObject(userString);
	List list = null;
	list = (List) 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 list = getUsers();
	for (User user : list) {
		System.out.println(user.getUsername());
	}


	JSONArray array = JSONArray.fromObject(list);
	System.out.println(array);
}

}

JSON-lib API ：Doc