黑马程序员JAVA高级视频_IO输入与输出19天7(字节流File读写操作)

package string.test;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/*
 * 字符流
 * FileReader
 * FileWriter
 * 
 * BufferedReader
 * BufferedWriter
 * 字节流
 * InputStream OutputStream
 * 
 */
public class InputStreamDemo {

    /**
     * @param args
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {
        // writer();
        // reader1();
        //reader2();
        reader3();

    }

    public static void writer() throws IOException {
        FileOutputStream fos = new FileOutputStream("demo.txt");
        fos.write("guwenrenzaichangsha".getBytes());
        fos.close();
    }

    /**
     * 单字节读取
     * 
     * @throws IOException
     */
    public static void reader1() throws IOException {
        FileInputStream fis = new FileInputStream("demo.txt");
        int len = 0;
        while ((len = fis.read()) != -1) {
            System.out.println((char) len);
        }
    }

    /**
     * 字节数组读取
     * 
     * @throws IOException
     */
    public static void reader2() throws IOException {
        FileInputStream fis = new FileInputStream("demo.txt");
        byte[] bytes = new byte[1024];
        int len = 0;
        while ((len = fis.read(bytes)) != -1) {
            System.out.println(new String(bytes, 0, len));
        }
    }

    /**
     * available 方式读取(文件较大不建议使用)
     * 
     * @throws IOException
     */
    public static void reader3() throws IOException {
        FileInputStream fis = new FileInputStream("demo.txt");
        byte[] bytes = new byte[fis.available()];
        fis.read(bytes);
        System.out.println(new String(bytes));
    }
}