java中字节输入流和输出流的简单使用例子

import java.io.IOException;

public class HelloWorld {
     public static void main(String []args) {
    	 File file=new File("D:\\HelloWorld.txt");//从D盘中的HelloWorld读取
    	 File filewrite=new File("D:\\HW.txt");//保存到HW中
    	 FileInputStream in;
		try {
			in = new FileInputStream(file);
			FileOutputStream out=new FileOutputStream(filewrite);
			byte [] b=new byte[(int)file.length()];
	    	 int t;
	    	 try {
				while((t=in.read(b))!=-1) {
					 out.write(b);
				 }
			} catch (IOException e) {
				e.printStackTrace();
			}
	    	 try {
				in.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
	    	 try {
				out.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} 
     }
}