Java基础05(补充二)-异或的应用

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

class Encrypt {
private static final int PASSWORD = 0x12345678;
private static final String SUFFIX = ".enc";

public void doEncrypt(String path) {
FileInputStream fis = null;
FileOutputStream fos = null;

try {
File file = new File(path);
File newFile = new File(path+SUFFIX);
fis = new FileInputStream(file); //FileNotFoundException
fos = new FileOutputStream(newFile); //FileNotFoundException
byte [] buf = new byte[1024];
int len = 0;
while((len=fis.read(buf))!=-1) { //IOException
for(int i = 0;i<len;i++)
{
buf[i]=(byte)(buf[i]^PASSWORD);
}
fos.write(buf,0,len); //IOException
}
}
catch(FileNotFoundException e) {
throw new RuntimeException("文件不存在,请重试!");
}
catch(IOException e) {
throw new RuntimeException("文件读取异常!");
}
finally {
try {
if(fis!=null)
fis.close();
}catch(Exception e ) {
throw new RuntimeException("文件读取流异常!");
}

try {
if(fos!=null)
fos.close();
}catch(Exception e) {
throw new RuntimeException("文件存储流异常!");
}
}
}

public void doDecrypt(String path) {
int index = path.lastIndexOf(SUFFIX);
if(index!=(path.length()-SUFFIX.length())) {
System.out.println("文件类型不正确!请重试!");
return;
}

FileInputStream fis = null;
FileOutputStream fos = null;

try {
File file = new File(path);
File newFile = new File(path.substring(0,index));
fis = new FileInputStream(file); //FileNotFoundException
fos = new FileOutputStream(newFile); //FileNotFoundException
byte [] buf = new byte[1024];
int len = 0;
while((len=fis.read(buf))!=-1) { //IOException
for(int i = 0;i<len;i++)
{
buf[i]=(byte)(buf[i]^PASSWORD);
}
fos.write(buf,0,len); //IOException
}
}
catch(FileNotFoundException e) {
throw new RuntimeException("文件不存在,请重试!");
}
catch(IOException e) {
throw new RuntimeException("文件读取异常!");
}
finally {
try {
if(fis!=null)
fis.close();
}catch(Exception e ) {
throw new RuntimeException("文件读取流异常!");
}

try {
if(fos!=null)
fos.close();
}catch(Exception e) {
throw new RuntimeException("文件存储流异常!");
}
}
}

public static void main(String [] args) {
Encrypt e = new Encrypt();
if(args.length != 2) {
System.out.println("参数输入错误!请重新输入!");
return;
}

if(args[0].equalsIgnoreCase("encrypt"))
e.doEncrypt(args[1]);
else if(args[0].toUpperCase().equals("DECRYPT")) {
e.doDecrypt(args[1]);
}

}
}