1.字节IO流

@SuppressWarnings("all")
public class ByteStreamMax {
    FileOutputStream fileOutputStream = null;
    FileInputStream fileInputStream = null;
    //打印文件内容
    public void inPut() throws IOException {
        File file = new File("D:\\IdeaProjects\\javase\\src\\test.txt");
        fileInputStream = new FileInputStream(file);
        byte[] bytes = new byte[1024];
        String str = "";
        while (fileInputStream.read(bytes) != -1) {
            str = new String(bytes, "utf-8");
            System.out.print(str);
        }
        System.out.println("\n");
        fileInputStream.close();
    }
    //修改文件内容
    public void outPut() throws IOException {
        File file1 = new File("D:\\IdeaProjects\\javase\\src\\test.txt");
        File file2 = new File("D:\\IdeaProjects\\javase\\src\\IOStream2");
        //读取file2的内容
        fileInputStream = new FileInputStream(file2);
        //将file2的内容写入到file1中
        fileOutputStream = new FileOutputStream(file1);
        byte[] bytes = new byte[1024];
        int len = 0;
        while ((len = fileInputStream.read(bytes)) != -1) {
            fileOutputStream.write(bytes, 0, len);
        }
        fileInputStream.close();
        fileOutputStream.flush();
        fileOutputStream.close();
    }
    public static void main(String[] args) throws IOException {
        ByteStreamMax byteStreamMax = new ByteStreamMax();
        //打印文件内容
        byteStreamMax.inPut();
        //修改文件内容
        byteStreamMax.outPut();
        //再次打印文件内容，检测是否已修改
        byteStreamMax.inPut();
    }
}