IO流

输入流

字节输入流：FileInputStream

//方法一：
public static void main(String args[]) throws IOException {
    FileInputString fi = new FileInputStream("a.txt");
    int by;
    while((by=fi.read())!=-1){
        System.out.println((char)by);
    }
    //关闭流输入
    fi.close();
}
//方法二：
public static void main(String args[]) throws IOException {
    FileInputString fi = new FileInputStream("a.txt");
    byte[] bytes = new byte[1024];
    int len;
    while((len=fi.read(bytes))!=-1){
        System.out.println(new String(bytes,0,len));
    }
}

字节缓冲输入流：BufferedInputStream

创建BufferedInputStream将创建一个内部缓冲区数组.当从流中读取或跳过字节时,内部缓冲区将根据需要从所包含的输入流中重新填充,一次很多字节

public static void main(String[] args){
    BufferedInputStream bf = new BufferedInputStream(new FileInputStream("a.txt"));
    byte[] bytes = new byte[1024];
    int len;
    while((len = bf.read(bytes))!=-1){
        System.out.println(new String(bytes,0,len));
    }
    bis.close();
}

输出流

字节输出流：FileOutPutStream

 public static void main(String[] args) throws Exception{      
    FileOutputStream fo = new FileOutputStream("a.txt");
    fo.write("AGE".getBytes());
    fo.close();
 }

字节缓冲输入流：BufferedOutputStream

 public static void main(String[] args) throws IOException {
        //字节缓冲输出流：BufferedOutputStream(OutputStream out)
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("a.txt"));
        //写数据
        bos.write("hello\r\n".getBytes());
        bos.write("world\r\n".getBytes());
        //释放资源
        bos.close();
 }