简单实现文件加密

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class Demo_02 {

	public static void main(String[] args) {
		File file = new File("Koala.jpg");
		BufferedInputStream bis = null;
		BufferedOutputStream bos = null;
		try{
			if(file.exists()){
				bis = new BufferedInputStream(new FileInputStream(file));
			}else{
				System.out.println("文件不存在");
			}
			//进行加密 加密后 再写出到新文件2.jpg
			bos = new BufferedOutputStream(new FileOutputStream("2.jpg"));
			int i = 0;
			while((i = bis.read())!=-1){
				bos.write(i^123^123);
				//一个数 异或另一个数两次 结果还是这个数本身
				bos.flush();
			}
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			try {
				if(bis!=null)
					bis.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			try {
				if(bos!=null)
					bos.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

}