Java字节与字符流永久存储json数据

public class User {
	public String userName; //名字
	public double balance; //金额
	public User() {
		super();
	}
	public User(String userName, double balance) {
		super();
		this.userName = userName;
		this.balance = balance;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public double getBalance() {
		return balance;
	}
	public void setBalance(double balance) {
		this.balance = balance;
	}
}

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import java.util.ArrayList;
import java.util.List;

import com.alibaba.fastjson.JSON;

public class ListFile {
	public static void main(String[] args){
		List<User> list=new ArrayList<>();
		list.add(new User("张三",100));
		list.add(new User("张四",200));
		list.add(new User("张五",300));
		File file=new File("D:/uselist.txt"); //存储的目标文件
		FileOutputStream fos=null;
		BufferedOutputStream bos=null;
		try{
			fos=new FileOutputStream(file);
			bos=new BufferedOutputStream(fos);
			String json=JSON.toJSONString(list); //对象转换为json
			bos.write(json.getBytes("utf-8")); //json字符串写入文件
			bos.flush();
			System.out.println("json数据写入完成");
		}
		catch(Exception e){
			e.printStackTrace();
		}
		finally{
			try{
				fos.close();
				bos.close();
			}
			catch(Exception e){
				e.printStackTrace();
			}
		}
		
		//读取文件内容，并在控制台输出
		String str="";
		int num=0;
		FileInputStream fis=null;
		BufferedInputStream bis=null;
		byte buff[]=new byte[1024];
		try{
			fis=new FileInputStream(file);
			bis=new BufferedInputStream(fis);
			while((num=bis.read(buff))!=-1){
				str+=new String(buff,"utf-8");
			}
			System.out.println(str); //打印读取文件的json字符串
		}
		catch(Exception e){
			e.printStackTrace();
		}
		finally{
			try{
				fis.close();
				bis.close();
			}
			catch(Exception e){
				e.printStackTrace();
			}
		}
		
		//把读取到的json数据再转为对象，并在控制台输出
		list=JSON.parseArray(str.trim(),User.class); //读取到的json数据存在空格，trim方法去除
		for(User obj:list){
			System.out.println(obj.getUserName()+"\t"+obj.getBalance());
		}
	}
}

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.List;

import com.alibaba.fastjson.JSON;

public class ListFile {
	public static void main(String[] args){
		List<User> list=new ArrayList<>();
		list.add(new User("张三",100));
		list.add(new User("张四",200));
		list.add(new User("张五",300));
		File file=new File("D:/uselist.txt"); //存储的目标文件
		FileWriter fw=null;
		BufferedWriter bw=null;
		
		try{
			fw=new FileWriter(file);
			bw=new BufferedWriter(fw);
			String json=JSON.toJSONString(list); //对象转换为json
			bw.write(json); //json字符串写入文件
			bw.flush();
			System.out.println("json数据写入完成");
		}
		catch(Exception e){
			e.printStackTrace();
		}
		finally{
			try{
				bw.close();
				fw.close();
			}
			catch(Exception e){
				e.printStackTrace();
			}
		}
		
		//读取文件内容，并在控制台输出
		String str="";
		String s="";
		FileReader fr=null;
		BufferedReader br=null;
		try{
			fr=new FileReader(file);
			br=new BufferedReader(fr);
			while((s=br.readLine())!=null){
				str+=s;
			}
			System.out.println(str); //打印读取文件的json字符串
		}
		catch(Exception e){
			e.printStackTrace();
		}
		finally{
			try{
				br.close();
				fr.close();
			}
			catch(Exception e){
				e.printStackTrace();
			}
		}
		
		//把读取到的json数据再转为对象，并在控制台输出
		list=JSON.parseArray(str.trim(),User.class);
		for(User obj:list){
			System.out.println(obj.getUserName()+"\t"+obj.getBalance());
		}
	}
}

json数据写入完成
[{"balance":100,"userName":"张三"},{"balance":200,"userName":"张四"},{"balance":300,"userName":"张五"}]
张三	100.0
张四	200.0
张五	300.0