课后作业

package 计算;

 import java.io.File; 
 import java.io.InputStream;
 import java.io.OutputStream; 
 import java.io.FileInputStream; 
 import java.io.FileOutputStream;
 public class FileAction1 { 
     private static final int numOfEncAndDec=0x99;//加密解密密钥 
     private static int dataOfFile=0;//文件字节内容
     public static void main(String[] args) { 
         File srcFile=new File("G:\encryption_text.txt");//初始化文件 
         File encFile=new File("G:\encryption_text01.txt"); //加密文件 
         File decFile=new File("G:\encryption_text02.txt"); //解密文件 
         try {
             EncFile(srcFile,encFile); //加密操作
             DecFile(encFile,decFile);
             }catch(Exception e) {
                 e.printStackTrace(); 
                 }
         } private static void EncFile(File srcFile,File encFile)throws Exception{
             if(!srcFile.exists()) {
                 System.out.println("source file not exixt");
                 } 
             if(!encFile.exists()) { 
                 System.out.println("encrypt file created");
                 encFile.createNewFile();//若无加密文件，新建一个加密文件 
                 } 
             InputStream fis=new FileInputStream(srcFile);
             OutputStream fos=new FileOutputStream(encFile); 
             while((dataOfFile=fis.read())>-1) {
                 //当读到文件内容时 
                 fos.write(dataOfFile^numOfEncAndDec);//将读出的内容加密后写入
                 } fis.close(); 
                 fos.flush();
                 fos.close();
                 } 
         private static void DecFile(File encFile,File decFile)throws Exception{ 
             if(!encFile.exists()) {
                 System.out.println("encrypt file not exixt"); 
                 } 
             if(!decFile.exists()) {
                 System.out.println("decrypt file created");
                 decFile.createNewFile();
                 } 
             InputStream fis=new FileInputStream(encFile);
             OutputStream fos=new FileOutputStream(decFile);
             while((dataOfFile=fis.read())>-1) {
                 fos.write(dataOfFile^numOfEncAndDec);
                 }
             fis.close();
             fos.flush();
             fos.close();
             } 
         }
     
 

import java.io.File;
  import java.io.FileInputStream; 
 import java.io.FileNotFoundException; 
 import java.io.FileOutputStream; 
 import java.io.IOException; 
 public class CutFile { 

public static void main(String[] args) { 
 
 cutFile("D:\file\file.txt", "D:\file2",1024 * 1024 * 20);
  }
 private static void cutFile(String src, String endsrc, int num) { 
 FileInputStream fis = null;
  File file = null;
  try { 
 fis = new FileInputStream(src); 
 file = new File(src); 
 //创建规定大小的byte数组 
 byte[] b = new byte[num]; 
 int len = 0; 
 //name为以后的小文件命名做准备 
 int name = 1;
  //遍历将大文件读入byte数组中，当byte数组读满后写入对应的小文件中 
 while ((len = fis.read(b)) != -1) { 
 //分别找到原大文件的文件名和文件类型，为下面的小文件命名做准备 
 String name2 = file.getName(); 
 int lastIndexOf = name2.lastIndexOf("."); 
 String substring = name2.substring(0, lastIndexOf); 
 String substring2 = name2.substring(lastIndexOf, name2.length()); 
 FileOutputStream fos = new FileOutputStream(endsrc + "\\"+ substring + "-" + name + substring2); 
 //将byte数组写入对应的小文件中 
 fos.write(b, 0, len); 
 //结束资源 36 fos.close();
  name++; 
 } 
 } catch (FileNotFoundException e) {
  e.printStackTrace();
  } catch (IOException e) {
  e.printStackTrace(); 
} finally {
  try { 
 if (fis != null) { 
 //结束资源 
 fis.close();
  } 
 } catch (IOException e) { 
 e.printStackTrace();
  }
  }
 }
  }