java.util.zip.ZipInputStream.read() Method Example

Description

The java.util.zip.ZipInputStream.read(byte[] buf, int off, int len) method reads from the current ZIP entry into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned.

Declaration

Following is the declaration for java.util.zip.ZipInputStream.read(byte[] buf, int off, int len) method.

public int read(byte[] buf, int off, int len)
   throws IOException

Parameters

• buf − The buffer into which the data is read.

• off − The start offset in the destination array b.

• len − The maximum number of bytes read.

Returns

The actual number of bytes read, or -1 if the end of the stream is reached.

Exceptions

• NullPointerException − If buf is null.

• IndexOutOfBoundsException − If off is negative, len is negative, or len is greater than buf.length - off.

• ZipException − If a ZIP file error has occurred.

• IOException − If an I/O error has occurred.

Pre-requisite

Create a file Hello.txt in D:> test > directory with the following content.

This is an example.

Example

The following example shows the usage of java.util.zip.ZipInputStream.read(byte[] buf, int off, int len) method.

package com.tutorialspoint;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Date;
import java.util.zip.Adler32;
import java.util.zip.CheckedOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

public class ZipInputStreamDemo {
   private static String SOURCE_FILE = "D:\\test\\Hello.txt";
   private static String TARGET_FILE = "D:\\test\\Hello.zip";

   public static void main(String[] args) {
      try {
         createZipFile();
         readZipFile();
      } catch(IOException ioe) {
         System.out.println("IOException : " + ioe);
      }
   }

   private static void createZipFile() throws IOException{
      FileOutputStream fout = new FileOutputStream(TARGET_FILE);
      CheckedOutputStream checksum = new CheckedOutputStream(fout, new Adler32());
      ZipOutputStream zout = new ZipOutputStream(checksum);

      FileInputStream fin = new FileInputStream(SOURCE_FILE);
      ZipEntry zipEntry = new ZipEntry(SOURCE_FILE);
      zout.putNextEntry(zipEntry);
      int length;
      byte[] buffer = new byte[1024];
      while((length = fin.read(buffer)) > 0) {
         zout.write(buffer, 0, length);
      }

      zout.closeEntry();
      fin.close();
      zout.close();
   }

   private static void readZipFile() throws IOException{
      ZipInputStream zin = new ZipInputStream(new FileInputStream(TARGET_FILE)); 

      ZipEntry entry;
      while((entry = zin.getNextEntry())!=null){
         System.out.printf("File: %s Modified on %TD %n", 
         entry.getName(), new Date(entry.getTime()));
         extractFile(entry, zin); 
         System.out.printf("Zip file %s extracted successfully.", SOURCE_FILE);
         zin.closeEntry();
      }
      zin.close();
   }

   private static void extractFile(final ZipEntry entry, ZipInputStream is) 
      throws IOException {
      FileOutputStream fos = null; 
      try { 
         fos = new FileOutputStream(entry.getName()); 
         final byte[] buf = new byte[1024]; 
         int read = 0; 
         int length; 
         while ((length = is.read(buf, 0, buf.length)) >= 0) { 
            fos.write(buf, 0, length); 
         } 
      } catch (IOException ioex) { 
         fos.close(); 
      } 
   }
}

Let us compile and run the above program, this will produce the following result −

File: D:\test\Hello.txt Modified on 05/22/17 
Zip file D:\test\Hello.txt extracted successfully.