Apache Commons IO - TeeInputStream

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It is an InputStream proxy that transparently writes a copy of all bytes read from the proxied stream to a given OutputStream. The proxied input stream is closed when the close() method on this proxy is called. It can be used to operate two streams collectively at a time.

Class Declaration

Following is the declaration for org.apache.commons.io.input.TeeInputStream Class −

public class TeeInputStream
   extends ProxyInputStream

Example of TeeInputStream Class

In this example, closing a TeeInputStream closes the TeeInputStream as well as TeeOutputStream objects.

IOTester.java

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import org.apache.commons.io.input.TeeInputStream;
import org.apache.commons.io.output.TeeOutputStream;

public class IOTester {

   private static final String SAMPLE = "Welcome to Howcodex. Simply Easy Learning.";
   public static void main(String[] args) {
      try {
         usingTeeInputStream();
      } catch(IOException e) {
         System.out.println(e.getMessage());
      }
   }

   public static void usingTeeInputStream() throws IOException {
      TeeInputStream teeInputStream = null;
      TeeOutputStream teeOutputStream = null;

      try {
         ByteArrayInputStream inputStream = new ByteArrayInputStream(SAMPLE.getBytes("US-ASCII"));
         ByteArrayOutputStream outputStream1 = new ByteArrayOutputStream();
         ByteArrayOutputStream outputStream2 = new ByteArrayOutputStream();

         teeOutputStream = new TeeOutputStream(outputStream1, outputStream2);
         teeInputStream = new TeeInputStream(inputStream, teeOutputStream, true);
         teeInputStream.read(new byte[SAMPLE.length()]);

         System.out.println("Output stream 1: " + outputStream1.toString());
         System.out.println("Output stream 2: " + outputStream2.toString());

      } catch (IOException e) {
         System.out.println(e.getMessage());
      } finally {
         //teeIn.close() closes teeIn and teeOut which in turn closes the out1 and out2.       
         try { 
            teeInputStream.close(); 
         } catch (IOException e) { 
            System.out.println(e.getMessage());
         }
      }
   }
}

Output

It will print the following result.

Output stream 1: Welcome to Howcodex. Simply Easy Learning.
Output stream 2: Welcome to Howcodex. Simply Easy Learning.
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