Java implementation of file read and write with compressed instances

This paper describes the implementation method of Java to read and write and compress files through an example, the specific code is as follows:

package com.toone.iform.action.common;

import java.io.BufferedReader; 
import java.io.BufferedWriter; 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.FileReader; 
import java.io.FileWriter; 
import java.io.IOException; 
import java.io.InputStream; 
import java.util.Enumeration; 
import java.util.Random; 
import java.util.zip.ZipEntry; 
import java.util.zip.ZipException; 
import java.util.zip.ZipFile;
public class TestFileIO {
  static String s = File.separator;
 
  private static void testInput() {
    //There is a Welcome. Java file under disk d. now read in bytes:
   int a = 0;
    // int counter=0;     
   FileInputStream f11;
    //The input stream
   try {
      f11 = new FileInputStream("D:" + s + "Welcome.java");
      while ((a = f11.read()) != -1)
        System.out.print((char) a); //In this case, the output is in bytes. Chinese characters cannot be output normally, because one Chinese character is two bytes.
       System.out.println("nn--------------------------------------------------n");
 
      FileReader f12 = new FileReader("D:" + s + "Welcome.java");
      while ((a = f12.read()) != -1)
        System.out.print((char) a);//Here is a character output, Chinese characters can be normal output
       System.out.println("nn--------------------------------------------------n");
 
      f11.close();//Close the file after reading it
      f12.close();//Close the file after reading it
      } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block       
       e.printStackTrace();
    } catch (IOException e) {
      // TODO Auto-generated catch block      
     e.printStackTrace();
    }
  }
 
  private static void testOutput() {
    //There is a Welcome. Java file under disk d. now read in bytes:
   int a = 0;
    //The output stream
   File f21 = new File("D:" + s + "testFile" + s + "test1.txt");
   //Define a new file f21, then determine if it exists in this directory, and if it does not, create it.
   if (!f21.exists()) {
      f21.getParentFile().mkdirs();
      try {
        f21.createNewFile();
        //Copy the contents of "welcome.java" to f21
        FileOutputStream fos = new FileOutputStream(f21);
        FileInputStream fis = new FileInputStream("D:" + s + "Welcome.java");//Read in the "welcome.java" file
        while ((a = fis.read()) != -1)
          fos.write(a);//Write the read in memory to fos, and now you get test1.txt is to copy welcome.java
        //Writer class
        FileWriter f22 = new FileWriter("D:" + s + "testFile" + s + "test2.txt");
        for (int i = 0; i < 65535; i++)
          f22.write(i);//Write to test2.txt. It can also be seen from here that the statement that determines whether the file exists or not in line 35-38 above can also be omitted.
        //Writes a string to a file
        FileWriter f23 = new FileWriter("D:" + s + "testFile" + s + "test3.txt");
        f23.write("Hello, world!");
 
        fos.close();
        fis.close();
        f22.close();
        f23.close();
      } catch (IOException e) {
        // TODO Auto-generated catch block
         e.printStackTrace();
      }
    }
  }
 
  private static void testBufferring() {
    //There is a Welcome. Java file under disk d. now read in bytes:
   int a = 0, counter = 0;
    //Buffered characters for efficient writing
   // BufferedWriter f31=new BufferedWriter(newFileWriter("D"+s+"testFile"+s+"test4.txt"));    
   BufferedWriter f31;
    try {
      f31 = new BufferedWriter(new FileWriter("D:" + s + "testFile" + s
          + "test4.txt"));
      for (int i = 1; i <= 100; i++) {
        f31.write(String.valueOf(new Random().nextInt(100)) + " ");
        if (i % 10 == 0)
          f31.newLine();
      }
      f31.flush();//The refresh buffer
      f31.close();
 
      BufferedReader f32 = new BufferedReader(new FileReader("D:" + s
          + "testFile" + s + "test4.txt"));
      String s32;
      System.out.println(" The output file f32 Content: ");
      while ((s32 = f32.readLine()) != null)
        System.out.println(s32);
      f32.close();
      System.out.println("n--------------------------------------------------n");
    } catch (IOException e) {
      // TODO Auto-generated catch block       
     e.printStackTrace();
    }
  }
 
  private static void testZip() {
    try {
      File f1 = new File("D:/test.zip");
      File f2 = new File("D:/testFile/testzip");
      ZipFile zf = new ZipFile(f1);
      testZipToUnzip(zf, f2);
 
    } catch (IOException e) {
      // TODO Auto-generated catch block
       e.printStackTrace();
    }
  }
 
  //Unzip the zipfile into file
  public static void testZipToUnzip(ZipFile zipfile, File file) {
    ZipEntry zentry = null;
    File zipout;
    InputStream zis = null;
    FileOutputStream fos = null;
    Enumeration e = zipfile.entries();//Zipfile directory
    while (e.hasMoreElements()) {
      zentry = (ZipEntry) e.nextElement();
      System.out.println(zentry.getName());//What are the files under zipfile? But why not output in order?
      //Put the unzipped file into the file folder:
      zipout = new File(file + s + zentry.getName());
 
      if (!zentry.isDirectory()) {
        try {
          zis = zipfile.getInputStream(zentry);
          if (!zipout.exists())
            zipout.getParentFile().mkdirs();
          fos = new FileOutputStream(zipout);
          byte[] b = new byte[1024];
          int length;
          while ((length = zis.read(b)) > 0) {
            fos.write(b, 0, length);
          }
          fos.close();
          zis.close();
        } catch (ZipException e1) {
          // TODO Auto-generated catch block           
         e1.printStackTrace();
        } catch (IOException e1) {
          // TODO Auto-generated catch block          
         e1.printStackTrace();
        }
      }
    }
  }
 
  public static void main(String[] args) throws ZipException {
    // TODO Auto-generated method stub
    testInput();
    testOutput();
    testBufferring();
    testZip();
  }
}