IO_FileInputStream&FileOutputStream

通过available()方法实现不阻塞输入流

        FileInputStream fis = new FileInputStream(f);
        try {
            //通过available()方法可以实现不阻塞流
            byte[] b = new byte[fis.available()];
            int result = 0;
            while((result = fis.read(b)) != -1) {
                System.out.println(new String(b, "utf-8"));
            }
        
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        fis.close();

读取文件

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class FileInputStreamJava {

    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        String strFile = "d:" + File.separator + "javatest" + File.separator + "IO_RandomAccessFileTest.txt";
        File f = new File(strFile);
        FileInputStream fis = new FileInputStream(f);
        byte[] b = new byte[1024];
        int result = 0;
        while((result = fis.read(b)) != -1) {
            //数组b固定大小1024，所以如果读到的数据不足，数组会自动填满，输出的时候结尾就可能会出现乱码
            //下面这种方式就出现了乱码
            //System.out.println(new String(b, "utf-8"));
            //现在这样就不会出现乱码了，重新组装成字符串的时候确定了最后一个字符串的byte数组大小
            System.out.println(new String(b,0,result, "utf-8"));
        }
        fis.close();
    }
}

每次读一个字节

public class FileInputStreamJava {

    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        String strFile = "d:" + File.separator + "javatest" + File.separator + "IO_RandomAccessFileTest.txt";
        File f = new File(strFile);
        FileInputStream fis = new FileInputStream(f);
        //byte[] b = new byte[1024];
        int result = 0;
        while((result = fis.read()) != -1) {
            //数组b固定大小1024，所以如果读到的数据不足，数组会自动填满，输出的时候结尾就可能会出现乱码
            //下面这种方式就出现了乱码
            //System.out.println(new String(b, "utf-8"));
            //现在这样就不会出现乱码了，重新组装成字符串的时候确定了最后一个字符串的byte数组大小
            System.out.print((char)result);
        }
        fis.close();
    }
}

写数据

import java.io.File;
import java.io.FileOutputStream;

public class FileOutputStreamJava {

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        String strFile = "d:" + File.separator + "javatest" + File.separator + "IO_RandomAccessFileTest.txt";
        File f = new File(strFile);
        //true，将字节写入文件末尾处，而不是写入文件开始处 
        FileOutputStream fos = new FileOutputStream(f, true);
        //  \r\n是windows系统的换行符
        byte[] b = "\r\n写出数据...".getBytes();
        fos.write(b);
        fos.close();
    }

}