IO流之FileInputStream

FileInputStream:文件输入流：

• 单个字节的读取，read()

 

package com.io.inputstream_;

import org.junit.jupiter.api.Test;

import java.io.FileInputStream;
import java.io.IOException;


/**
 * FileInputStream
 */
public class FileInputStream_ {
    public static void main(String[] args) {

    }
    @Test
    public void readFile01(){
        String filePath="d:\\hello.txt";
        int readData=0;
        FileInputStream fileInputStream=null;
        try {
            fileInputStream=new FileInputStream(filePath);

            while ((readData=fileInputStream.read())!=-1){
                System.out.print((char)readData);//读的时候是int类型，显示的时候要转成char类型
            }
        } catch (IOException e) {
            e.printStackTrace();

        }finally {
            try {
                fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }
}

 

 

 

多个字节的读取，read（byte[] b）

从该输入流读取最多b.length字节的数据到字节数组。

package com.io.inputstream_;

import org.junit.jupiter.api.Test;

import java.io.FileInputStream;
import java.io.IOException;


/**
 * FileInputStream
 */
public class FileInputStream_ {
    public static void main(String[] args) {

    }
    @Test
    public void readFile01(){
        String filePath="d:\\hello.txt";
        //定义字节数组
        byte[] buf=new byte[8];//一次读取8个字节
        int readLen=0;
        FileInputStream fileInputStream=null;
        try {
            fileInputStream=new FileInputStream(filePath);

            while ((readLen=fileInputStream.read(buf))!=-1){
                System.out.print(new String(buf,0,readLen));//读的时候是int类型，显示的时候要转成char类型
            }
        } catch (IOException e) {
            e.printStackTrace();

        }finally {
            try {
                fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }
}