java -io 读取文件操作

主要分为字节读取和字符读取，字节读取可以一个一个读取和字节数组读取，字符读取同样之，字符读取适合文本读取，字节读取皆可以

这里直接上代码，读取文件的9个小demo

package com.io;

import org.junit.Test;

import java.io.*;

public class FileTest {
    //1、字节流字节一个一个读取
    @Test
    public void test() throws IOException{
        InputStream fis = new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt"));
        int len;
        //按字节一个一个读取
        while ((len = fis.read())!=-1){
            System.out.print((char)len+"\t");
        };
        fis.close();
    }
//输出结果h    e    l    l    o    w    o    r    l    d   
 
    //2、字节流字节数组读取
    @Test
    public void test1() throws IOException{
        InputStream fis = new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt"));
        byte[] bytes = new byte[2];
        int len ;
        //按字节数组读取 bytes存储的是读取的数据
        while ((len = fis.read(bytes))!=-1){
            System.out.print((new String(bytes))+"\t");
        };
        fis.close();
    }
//输出结果 he    ll    ow    or    ld    

    //3、缓冲字节流字节一个一个读取
    @Test
    public void test2() throws IOException{
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt")));
        int len ;
        while ((len = bis.read())!=-1){
            System.out.print((char)len+"\t");
        };
        bis.close();
    }

//输出结果h    e    l    l    o    w    o    r    l    d  

    //4、缓冲字节流字节数组读取
    @Test
    public void test3() throws IOException{
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt")));
        byte[] bytes  = new byte[3];
        int len ;
        //按字节数组读取 bytes存储的是读取的数据
        while ((len = bis.read(bytes))!=-1){
            System.out.print(new String(bytes)+"\t");
        };
        bis.close();
    }
//输出结果hel    low    orl    drl    

    //5、字符流一个一个读取
    @Test
    public void test4() throws IOException{
        InputStreamReader isr = new InputStreamReader(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt")));
        int len ;
        //按字节数组读取 bytes存储的是读取的数据
        while ((len = isr.read())!=-1){
            System.out.print((char)len+"\t");
        };
        isr.close();
    }


    //6、字符流字符数组读取
    @Test
    public void test5() throws IOException{
        InputStreamReader isr = new InputStreamReader(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt")));
        char[] chars = new char[3];
        int len ;
        //按字节数组读取 bytes存储的是读取的数据
        while ((len = isr.read(chars))!=-1){
            System.out.print(new String(chars)+"\t");
        };
        isr.close();
    }

    //7、缓冲字符流字符一个一个读取
    @Test
    public void test6() throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt"))));
        int len ;
        //按字节数组读取 bytes存储的是读取的数据
        while ((len = br.read())!=-1){
            System.out.print((char)len+"\t");
        };
        br.close();
    }

    //8、缓冲字符流字符数组读取
    @Test
    public void test7() throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt"))));
        char[] chars = new char[3];
        int len ;
        //按字节数组读取 bytes存储的是读取的数据
        while ((len = br.read(chars))!=-1){
            System.out.print(new String(chars)+"\t");
        };
        br.close();
    }

    //9、缓冲字符流按行读取
    @Test
    public void test8() throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:\\project_test\\src\\com\\io\\readme.txt"))));
        //按字节数组读取 bytes存储的是读取的数据
        String str;
        while ( (str = br.readLine())!=null){
            System.out.print(str+"\t");
        };
        br.close();
    }
}

待更。。。。。。。。。。。。。。

java -io 读取文件操作

原文：https://www.cnblogs.com/tdyang/p/10834577.html