Update: The php/java bridge files needed to run this tutorial as it was created orginally can be downloaded from here( version 3.2.1) . The present version of the php java bridge does not support this windows version of the tutorial.

Here's how to team up two of the most popular and powerful platforms for web development together. With the php-java bridge you can build classes and jar files in Java and call them and use their methods in PHP. Use the quick and easy PHP language to bring Java muscle to your web pages.

In this tutorial I am using Windows 2000 Server, PHP 5.1.4 and php-java bridge 3.1.6. Windows is my operating system of choice but there is information on installing and using php-java bridge on Linux and Mac OS. You can find it under the resource link at the end of the article. I am going to assume that you have a bit of knowledge about both PHP and Java. You should know enough to get them installed and be able to do simple coding in both.

JDK

Download and install Java 5 JDK. You can use the Java 6 Beta if you like but the latest stable is jdk 1.5.0_09. I wanted to make sure my rusty Java skills were not further hindered by a beta software glitch. It's bad enough that everything I have learned in Java 2 and all my book samples bring up those nasty deprecated messages whenever I try to compile something.

Once you have installed the JDK you will need to adjust the PATHS to point to the Java installation and the set a CLASSPATH. Follow the next steps.

Create an AUTOEXEC.BAT file

1. Click on START (lower left)
2. Click on run
3. Where is says "open" type in "command" and click OK.  This gets you to the DOS prompt.
4. Type "cd c:\"
5. Type "notepad autoexec.bat"  -- this will bring up the notepad editor.  In this editor type the following two lines:
   set PATH=%PATH%;C:\Program Files\Java\jdk1.5.0_09\bin;
   set CLASSPATH=.
6. Exit notepad.

Wampserver

Wampserver is my choice of Apache2, MySQL and PHP. I find that it is easier and lighter weight than XAMPP. All too frequently I get emails about how to do things in XAMPP. The answer is, the same way as you would in Wampserver. My feeling is if XAMPP is your choice then you should take sometime to learn about it. There is just not enough difference between the two to make doing a seperate article necessary. They are both WAMP packages in the end.

The PHP-Java Bridge

This is the key to getting everything to work. The php-java bridge is a dll file. It is stable but does not seem to be documented very well. I have a feeling this will change soon but until then you need to know a few things to get it going. The first thing is that the files once downloaded and decompressed do not show. This threw me off for a while until I decided to test the functions. When I launched the test.bat file the rest of the installation files appeared.

So I copied the directory holding them over to the preset Apache htdocs directory for wampserver and surfed to the test.php that was showing. The result was a warning that I was using the wrong php-java.dll and php-java.jar file. These incorrect files were the ones that came with the installation ow Wampserver. The next step was to copy the correct files files from the php-java install directory over to the Wampserver Apache PHP directory where the PHP extensions were stored. Then I surfed to the test page again and was greeted by phpinfo screen and other information that could only come from PHP talking to Java. Very cool!

Java

From here things get easier and easier. The code below is your sample Java code that needs to be compiled into a Java class to be called from PHP. Take the code show below and place it in a text editor and save it as "hello.java" in a directory. Compiling is easy just start up the command prompt go to the directory holding the hello.java file and give the c:> javac hello.java command. This will create a hello.class file. You can leave it there and give the path to it when coding your PHP.

For those that don't know much Java yet here's some Hello World code with a little spice to it so it does not get boring.

//------------------------------------------------------------------ 
import java.util.*;
import java.text.*;
import java.math.*;

public class hello { 
public static void main(String[] args) { 
//do nothing - this will keep us from getting a compile error 
} 
public String SayHello() {
  Date today = new Date();
  return "Hello Geek here is the java date and time: " + today; 
}

public int SayNumber(){
  int mynum = 0;
    for(int i=1;i<=5;i++){
       mynum =+ (int)(Math.random()*100);
    }
    return mynum;
}
} //------------------------------------------------------------------

PHP

The PHP code here is simple and straight forward. It is not OOP. But you probably got enough of that while doing the Java code.

That's it. Now browse to the PHP page and you should get the results shown below.

Make note of the @java_reset() function at the end of the PHP snippet. It is very important to remember to add this while testing. This is because the Java JVM caches the call to and the Java object. Without java_reset() when you update a class file you will get the previously cached one instead.

More code and tips on installation to Mac OSX and Linux OS can be found here at php.net. If you need support there is a mailing list at php-java-bridge-users@lists.sourceforge.net. Though there is little activity the core developers of the php-java bridge are there to help.

Conclusion

The php-java bridge is stable and should not be hard to talk a web hosting provider into installing if they have not done so already. While Java hosting is not as wide-spread as PHP with the recent changes made in the licensing this will change also. The best part of all is that this gives PHP programmers a good reason to learn Java and vice versa.

Related:

• How to bridge PHP and Java on Windows IIS
• How to bridge PHP and Java on Windows with Apache Tomcat

Happy Publishing!

Pia Weathers - database systems engineer