Java I/O 缓冲流、打印流

1.缓冲流创建

public static void main(String[] args) {
    try (BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream("test.txt"))){   //传入FileInputStream
        System.out.println((char) bufferedInputStream.read());   //操作和原来的流是一样的
    }catch (IOException e){
        e.printStackTrace();
    }
}

2.我们可以对BufferedInputStream进行reset()mark()操作

public static void main(String[] args) {
    try (BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream("test.txt"))){
        bufferedInputStream.mark(1);   //只保留之后的1个字符
        System.out.println((char) bufferedInputStream.read());
        System.out.println((char) bufferedInputStream.read());
        bufferedInputStream.reset();   //回到mark时的位置
        System.out.println((char) bufferedInputStream.read());
        System.out.println((char) bufferedInputStream.read());
    }catch (IOException e) {
        e.printStackTrace();
    }
}

3.缓冲输入字符流

public static void main(String[] args) {
    try (BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream("output.txt"))){
        outputStream.write("lbwnb".getBytes());
        outputStream.flush();
    }catch (IOException e) {
        e.printStackTrace();
    }
}

4.缓冲字符流

public static void main(String[] args) {
    try (BufferedReader reader = new BufferedReader(new FileReader("test.txt"))){
        System.out.println((char) reader.read());
    }catch (IOException e) {
        e.printStackTrace();
    }
}

相比Reader更方便的是,它支持按行读取:

public static void main(String[] args) {
    try (BufferedReader reader = new BufferedReader(new FileReader("test.txt"))){
        System.out.println(reader.readLine());   //按行读取
    }catch (IOException e) {
        e.printStackTrace();
    }
}

5.Stream流

public static void main(String[] args) {
    try (BufferedReader reader = new BufferedReader(new FileReader("test.txt"))){
        reader
                .lines()
                .limit(2)
                .distinct()
                .sorted()
                .forEach(System.out::println);
    }catch (IOException e) {
        e.printStackTrace();
    }
}

6.转换流

当读取的是一个字符串或是一个个字符,但只能往一个OutputStream里输出,但是OutputStream又只支持byte类型,如果要往里面写入内容,就会使用到转换流

public static void main(String[] args) {
    try(InputStreamReader reader = new InputStreamReader(new FileInputStream("test.txt"))){  //虽然给定的是FileInputStream,但是现在支持以Reader的方式进行读取
        System.out.println((char) reader.read());
    }catch (IOException e){
        e.printStackTrace();
    }
}

你可能感兴趣的:(java,开发语言)