输入流常见操作

1.输入流读取文件中的字符串

package com.ydlclass.feature;

import org.junit.Test;

import java.io.*;

public class IOTest {
    //文件流的使用步骤,例如读取a.t
    @Test
    public void testRead1() throws FileNotFoundException {
        String path = "E:\\元气壁纸缓存\\img_cache\\a.txt";
        File file = new File(path);
        FileInputStream fileInputStream = new FileInputStream(file);//使用一个文件输入流，对接到文件上面去
        int read;
        int i = 0;
        byte[] bytes = new byte[10];
        try {
            while ((read = fileInputStream.read()) != -1){
                byte b = (byte)read;
                bytes[i] = b;
                i++;
            }
            System.out.println(new String(bytes));

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Test
    //第二个read方法的使用以及返回值的含义,参数中需要一个byte数组保存起来；返回值是读取的字节个数
    public void testRead2() throws IOException {
        String path = "E:\\元气壁纸缓存\\img_cache\\a.txt";
        File file = new File(path);
        InputStream inputStream = new FileInputStream(file);
        byte[] bytes = new byte[10];
        int read;
        while ((read = inputStream.read(bytes)) != -1){
            System.out.println(new String(bytes,0,bytes.length - 1));//使用这种方式避免字符串之后的为乱码
        }

        //替换掉上面的内容


        //String path1 = "E:\\元气壁纸缓存\\img_cache\\a.txt";
        //File file1 = new File(path);
        //InputStream inputStream1 = new FileInputStream(file);
        //byte[] bytes1 = new byte[10];
        //int read1;
        //StringBuilder sb = new StringBuilder();
        //while ((read1 = inputStream.read(bytes)) != -1){
        //    //每次读出多少个字节，就将多少个字节变为字符串
        //    String s = new String(bytes,0,read1);
        //    sb.append(s);
        //}
        //System.out.println(sb);
    }
}