IO 流-字节流-字符流-缓冲流

来源：互联网发布：linux 引导文件丢失编辑：程序博客网时间：2024/06/01 09:03

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;

// 字节流：    FileOuputStream    FileInputStream
// 字符流：    FileWriter         FileReader
// 缓冲流：    BufferedWriter      BufferedReader
public class IO {
    public static void main(String[] args){
        fileReader();
       /*fileOutputStream();
       bufferedWriter();
      bufferedReader();
      fileInputStream();*/
    }

    //字节流   输出流
    public static void fileOutputStream(){
       File f = new File("e:\\text.txt"); //指定到支持的文件

        try{
            //文件不存在时创建
            if(f.exists()==false){
                f.createNewFile();
            }
            FileOutputStream fos = new FileOutputStream(f);
            String str = "今天的天气很闷沉";
            byte[] b = str.getBytes();
            fos.write(b);
            fos.close();
        }catch(Exception ex){
            ex.printStackTrace();
       }
    }

    //字符流输出流
    public static void fileWriter(){
        File f = new File("e:\\text.txt");
        try{

            if(f.exists()==false){
                f.createNewFile();
            }
            FileWriter fw = new FileWriter(f,true); //true 表示不覆盖文件里面的内容
            String str = "今天的天气很闷沉";
            char[] ch = str.toCharArray();
            fw.write("\r\n");   //写入换行
            fw.write(ch);
            fw.close();
        }catch(Exception ex){
            ex.printStackTrace();
        }
    }

    // 缓冲流   输出流
    public static void bufferedWriter(){
        File f = new File("e:\\text.txt");
        try{

            if(f.exists()==false){
                f.createNewFile();
            }
            BufferedWriter bw = new BufferedWriter(new FileWriter(f,true)); // 以字符流的对象为参数

            //缓冲流可以直接操作字符
            bw.write("\r\n");
            bw.write("天气不是很好！");

            bw.close();
        }catch(Exception ex){
            ex.printStackTrace();
       }
    }

    //字节流输入流
   public static void fileInputStream(){
       File f = new File("e:\\text.txt");
        try{

            if(f.exists()==false){
                f.createNewFile();
            }
            FileInputStream fis = new FileInputStream(f);

            // 字节数组的长度，由文件的字节大小
           byte[] b = new byte[(int)f.length()];
           fis.read(b);        //读入数据

           String str = new String(b); //以字节数组构建字符串
           fis.close();
            System.out.println(str);
       }catch(Exception ex){
            ex.printStackTrace();
        }
    }

    //字符流输入流
    public static void fileReader(){
      File f = new File("e:\\text.txt");
        try{
           if(!f.exists()){
                f.createNewFile();
            }

            FileReader fr = new FileReader(f);
            //BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in,"gb2312")); //设置输入接口按中文编码
            //BufferedWriter stdout = new BufferedWriter(new OutputStreamWriter(System.out,"gb2312")); //设置输出接口按中文编码

            StringBuffer sb = new StringBuffer();
            char[] ch = new char[1000]; // 字符的长度未知
            int hasRead = 0;
            while((hasRead=fr.read(ch))>0){
                sb.append(new String(ch,0,hasRead));
            }

           fr.close();
           //String gb = new String(sb.toString().getBytes("ISO-8859-1"),"UTF-8");
            System.out.println(sb);
        }catch(Exception ex){
            ex.printStackTrace();
        }
    }

    //缓冲刘输入流
    public static void bufferedReader(){
        File f = new File("e:\\text.txt");
        try{
            if(!f.exists()){
                f.createNewFile();
            }
            BufferedReader br = new BufferedReader(new FileReader(f)); //字符流的对象构造

            //每次读取文件的一行
            StringBuffer sb = new StringBuffer();
            while(br.ready()){ //是否有读取内容
                sb.append(br.readLine());   //读取一行
                sb.append("\r\n");      //换行
            }
            br.close();
            System.out.println(sb);

        }catch(Exception ex){
            ex.printStackTrace();
        }
    }
}