IO流——缓冲流的使用

缓冲流：BufferedInputStream、BufferedOuputStream、BufferedReader、BufferedWriter

目的：通过使用缓存，加快读取和写入数据的速度。

缓冲流是一种包装流。

示例代码：

public class TestBufferedStream {

    private static File source;
    private static File target;

    static {
        //io和bufferedstream这两个文件夹一定要存在
        source = new File("io"+File.separator+"bufferedstream"+File.separator+"source.txt");
        target = new File("io"+File.separator+"bufferedstream"+File.separator+"target.txt");

        if(!source.exists()){
            try {
                source.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        if(!target.exists()){
            try {
                target.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) throws IOException {
//        testBufferedWriter();
        testBufferedOutputStream();
//        testBufferedReader();
        testBufferedInputStream();
    }

    public static void testBufferedInputStream() throws IOException {
        BufferedInputStream in = new BufferedInputStream(new FileInputStream(source));
        byte[] data = new byte[10];
        int len;
        while((len = in.read(data))!= -1){
            System.out.print(new String(data,0,len));
        }

        in.close();


    }

    public static void testBufferedOutputStream() throws IOException {
        BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(source,false));
        out.write(65);
        byte[] data = "我是kkk".getBytes();
        String s = new String(data,0,data.length,"ASCII");//这里会乱码，因为ASCII码每个字符（数字、英文）一个字节，识别不了中文
//        out.write("bcdefghijklmnopqrst我aa叫changshuchao".getBytes());
        out.write(s.getBytes("ASCII"));
        out.flush();
        out.close();

    }

    public static void testBufferedReader() throws IOException {
        BufferedReader reader = new BufferedReader(new FileReader(target));
        char[] data = new char[10];
        int len;
        while((len = reader.read(data) )!=-1){
            System.out.println(new String(data,0,len));
        }

        reader.close();
    }

    public static void testBufferedWriter() throws IOException {
        BufferedWriter writer = new BufferedWriter(new FileWriter(source,false));
        writer.write("我");
//        writer.write(new String("叫changshuchao".getBytes("UTF-8")),0,10);
        writer.write("叫changshuchao我".toCharArray(),0,12);

        writer.close();
    }

}