java对程序的简单加密

File file = new File("oppo.in");
File file1 = new File("main.in");
GregorianCalendar gc =new GregorianCalendar();
SimpleDateFormat sf =new SimpleDateFormat("yyyyMMdd");
if(!file.exists())
{
try {
file.createNewFile();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
Date d=new Date();
String aa=sf.format(d);

	        byte bt[] = new byte[1024];  
	        bt = aa.getBytes();  
	        try {  
	            FileOutputStream in = new FileOutputStream(file);  
	            try {  
	                in.write(bt, 0, bt.length);  
	                in.close();  
	                // boolean success=true;  
	                // System.out.println("写入文件成功");  
	            } catch (IOException e1) {  
	                // TODO Auto-generated catch block  
	                e1.printStackTrace();  
	            }  
	        } catch (FileNotFoundException e1) {  
	            // TODO Auto-generated catch block  
	            e1.printStackTrace();  
	        }  
	        
    }else{
    	Date d=null;
		Date d2 = null;
		
		d=new Date();
		String str1="";
        try {  
        	  FileInputStream in=new FileInputStream(file);

              // size  为字串的长度 ，这里一次性读完

              int size=in.available();

              byte[] buffer=new byte[size];

              in.read(buffer);

              in.close();

              str1=new String(buffer,"GB2312");
             
        } catch (Exception e1) {  
            // TODO: handle exception  
        }
        
	
		try {//字符串转换为时间
			d2 = sf.parse(str1);
			
		} catch (ParseException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		
		gc.setTime(d);
		
		String s1=sf.format(gc.getTime());
	
		try {
			 d=sf.parse(s1);
		} catch (ParseException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		
		long tt=d.getTime()-d2.getTime();
		long days = tt/ (1000 * 60 * 60 * 24);//计算时间
		System.out.println(days);
		if(days>=30){
			
			
			 String str="";
			 int password;
			 String str11="";
			 String a = "";
		        try {  
		        	  FileInputStream in=new FileInputStream(file1);

		              // size  为字串的长度 ，这里一次性读完

		              int size=in.available();

		              byte[] buffer=new byte[size];

		              in.read(buffer);

		              in.close();

		              str=new String(buffer,"GB2312");
		          password=Integer.parseInt(str)*Integer.parseInt(str)*Integer.parseInt(str);
		          str11=password+"";
		         a=str11.substring(0,3);
		  		
		  			
		        } catch (Exception e1) {  
		            // TODO: handle exception  
		        }  
		        
		        byte bt[] = new byte[1024];  
		        bt = a.getBytes();  
		        try {  
		            FileOutputStream in = new FileOutputStream(file1);  
		            try {  
		                in.write(bt, 0, bt.length);  
		                in.close();  
		                // boolean success=true;  
		                // System.out.println("写入文件成功");  
		            } catch (IOException e1) {  
		                // TODO Auto-generated catch block  
		                e1.printStackTrace();  
		            }  
		        } catch (FileNotFoundException e1) {  
		            // TODO Auto-generated catch block  
		            e1.printStackTrace();  
		        }  
				Date d1=new Date();
		        String aa=sf.format(d1);
		        byte bt1[] = new byte[1024];  
		        bt1 = aa.getBytes();  
		        try {  
		            FileOutputStream in = new FileOutputStream(file);  
		            try {  
		                in.write(bt1, 0, bt1.length);  
		                in.close();  
		                // boolean success=true;  
		                // System.out.println("写入文件成功");  
		            } catch (IOException e1) {  
		                // TODO Auto-generated catch block  
		                e1.printStackTrace();  
		            }  
		        } catch (FileNotFoundException e1) {  
		            // TODO Auto-generated catch block  
		            e1.printStackTrace();  
		        }  
		}
    }