XLVIII. Java

There are two possible ways to bridge PHP and Java: you can either integrate PHP into a Java Servlet environment, which is the more stable and efficient solution, or integrate Java support into PHP. The former is provided by a SAPI module that interfaces with the Servlet server, the latter by the Java extension.

PHP 4 ext/java provides a simple and effective means for creating and invoking methods on Java objects from PHP. The JVM is created using JNI, and everything runs in-process. Build instructions for ext/java can be found in php4/ext/java/README.

Esimerkki 1. Java Example

<?php
  // get instance of Java class java.lang.System in PHP
  $system = new Java('java.lang.System');

  // demonstrate property access
  print 'Java version='.$system->getProperty('java.version').' <br>';
  print 'Java vendor=' .$system->getProperty('java.vendor').'  <br>';
  print 'OS='.$system->getProperty('os.name').' '.
              $system->getProperty('os.version').' on '.
              $system->getProperty('os.arch').' <br>';

  // java.util.Date example
  $formatter = new Java('java.text.SimpleDateFormat',
                        "EEEE, MMMM dd, yyyy 'at' h:mm:ss a zzzz");

  print $formatter->format(new Java('java.util.Date'));
?>

Esimerkki 2. AWT Example

<?php
  // This example is only intented to be run as a CGI.

  $frame  = new Java('java.awt.Frame', 'PHP');
  $button = new Java('java.awt.Button', 'Hello Java World!');

  $frame->add('North', $button);
  $frame->validate();
  $frame->pack();
  $frame->visible = True;

  $thread = new Java('java.lang.Thread');
  $thread->sleep(10000);

  $frame->dispose();
?>

Notes:

new Java() will create an instance of a class if a suitable constructor is available. If no parameters are passed and the default constructor is useful as it provides access to classes like java.lang.System which expose most of their functionallity through static methods.
Accessing a member of an instance will first look for bean properties then public fields. In other words, print $date.time will first attempt to be resolved as $date.getTime(), then as $date.time.
Both static and instance members can be accessed on an object with the same syntax. Furthermore, if the java object is of type java.lang.Class, then static members of the class (fields and methods) can be accessed.
Exceptions raised result in PHP warnings, and NULL results. The warnings may be eliminated by prefixing the method call with an "@" sign. The following APIs may be used to retrieve and reset the last error:
- java_last_exception_get()
- java_last_exception_clear()
Overload resolution is in general a hard problem given the differences in types between the two languages. The PHP Java extension employs a simple, but fairly effective, metric for determining which overload is the best match.
Additionally, method names in PHP are not case sensitive, potentially increasing the number of overloads to select from.
Once a method is selected, the parameters are cooerced if necessary, possibly with a loss of data (example: double precision floating point numbers will be converted to boolean).
In the tradition of PHP, arrays and hashtables may pretty much be used interchangably. Note that hashtables in PHP may only be indexed by integers or strings; and that arrays of primitive types in Java can not be sparse. Also note that these constructs are passed by value, so may be expensive in terms of memory and time.

sapi/servlet builds upon the mechanism defined by ext/java to enable the entire PHP processor to be run as a servlet. The primary advanatage of this from a PHP perspective is that web servers which support servlets typically take great care in pooling and reusing JVMs. Build instructions for the Servlet SAPI module can be found in php4/sapi/README. Notes:

While this code is intended to be able to run on any servlet engine, it has only been tested on Apache's Jakarta/tomcat to date. Bug reports, success stories and/or patches required to get this code to run on other engines would be appreciated.
PHP has a habit of changing the working directory. sapi/servlet will eventually change it back, but while PHP is running the servlet engine may not be able to load any classes from the CLASSPATH which are specified using a relative directory syntax, or find the work directory used for administration and JSP compilation tasks.

Sis�llys
java_last_exception_clear -- Clear last Java exception
java_last_exception_get -- Get last Java exception

Yes, in fact it works perfect. You'll have to have the JDK installed, PHP Java extension compiled (--with-java), and the apropriate [Java] section settings in your php.ini first though. It seems like the majority of problems that users report about this on unix/linux platforms has to do with getting those php.ini settings right, since they vary depending on what brand of JRE you use. Suggest searching the web for "PHP Java integration php.ini" for more info.

If you get the 'Couldn't create Virtual Machine' error without any further explanation, you could try and add the following setting to Apache's environment. LD_LIBRARY_PATH=/usr/lib/j2sdk1.3/jre/lib/i386/classic:/usr/lib/j2sdk1.3/jre/lib/i386 (Running Debian 2.2 / Apache 1.3.19 / PHP 4.0.6 / Blackdown JDK 1.3.1)

An _very_ important thing here is to remember that the apache must be linked with pthreads (do "LDFLAGS=-lpthread ./configure <options>", or like me, add it the the .spec file). You can check if your apache is pthreaded with "ldd $(which httpd)" if you like. I experianced a lot of hangs/errors due to this problem, it's a shame that it's not in the docs / README (i didn't find it). Magnus

Hi all, After struggling for some time and referring to numerous confusing articles , I finally came up with a working Java section in php.ini, for Linux (RedHat 6.2) with Apache 1.3.22 and Sun JDK 1.3.1. [Java] java.class.path=/usr/local/lib/php/php_java.jar:/home/sinanet/www java.home = /usr/java java.library=libjava.so extension_dir=/usr/local/lib/php/extensions/no-debug-non-zts-20010901 extension=libphp_java.so Please substitute your document root for /home/sinanet/www , and your extension_dir (it varies from version to version ) to libphp_java.so for extension_dir here. I have tried this configuration with php 4.0.6, 4.1.0, and 4.1.1. It works pretty well. And I think this may save some of your time to look for a working [Java] section. Yen-Wei Liu

I agree Xavier. My php.ini settings is: [java] java.class.path = /usr/local/etc/php4/ext/java/php_java.jar java.home = /usr/local/jdk1.3.1_02 java.library = /usr/local/jdk1.3.1_02/jre/lib/i386/hotspot/libjvm.so extension_dir = /usr/local/etc/php4/modules extension = libphp_java.so When I set java.library=libjava.so and java.library.path, it doesn't work. Maybe this will help the later. BTW. I found the PHP4.1.0 and PHP4.1.1 cann't generate libphp_java.so, if it happen to you, you can use PHP4.0.6. Jonathan

I managed to get it working with IBM Java SDK 1.3.0 but it was not easy. Here's my php.init: [Java] extension = libphp_java.so java.library.path = /usr/local/lib/php/extensions/no-debug-non-zts-20010901 java.class.path = /usr/local/lib/php/php_java.jar java.home = /opt/IBMJava2-13 java.library = /opt/IBMJava2-13/jre/bin/classic/libjvm.so Besides, I had to edit the httpd init.d script to include the statement: export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/IBMJava2-13/jre/bin:\ /opt/IBMJava2-13/jre/bin/classic I guess java.library.path should serve for this, but it didn't worked.

Hello, There are two more useful links on phpbuilder.com in the PHP&JAVA discussion. They are related to the PHP and Java integration on Unix/Linux. My settings (see above) is like that in the 1st link. Moreover, I have the path to java in my PATH env. variable, so MAYBE its why my libjava.so works. I couldn't find the origin of libjava.so, but now looks there are libjava.so and libjvm.so two options. I built my php from the source package, and libphp_java.so does exist, at least on my RH6.2 with Apache 1.3.19 and Sun JDK 1.3.1. libphp_java.so should be found under php-4.1.1/ext/java/.libs . If you want to find some more discussion about PHP & Java integration, you may try www.phpbuilder.com and look for php&java. It's a good place to start with. Yen-Wei Liu

Hi there, i have the same problems finding the correct php.ini section for my system. my configuration is: freebsd 4.4, mysql 3.23.47, mod_php4.1.1, linux-jdk1.3.1, apache 1.3.22_mod_ssl, all ports installation './configure' '--with-apxs=/usr/local/sbin/apxs' '--with-config-file-path=/usr/local/etc' '--enable-versioning' '--with-system-regex' '--disable-debug' '--enable-track-vars' '--without-gd' '--without-mysql' '--with-zlib' '--with-java=/usr/local/linux-jdk1.3.1' '--with-mysql=/usr/local' '--prefix=/usr/local' 'i386--freebsd4.5' i got the following error: Fatal error: Unable to load Java Library /usr/local/linux-jdk1.3.1/jre/lib/i386/hotspot/libjvm.so, error: Shared object "libnsl.so.1" not found in /usr/local/www/data.default/phpjavatest3.php on line 2 php.ini [java] java.class.path = /usr/local/lib/php/php_java.jar java.home = /usr/local/linux-jdk1.3.1 java.library = /usr/local/linux-jdk1.3.1/jre/lib/i386/hotspot/libjvm.so extension_dir = /usr/local/lib/php/20010901 extension = libphp_java.so Have anyone an idea ? thomas

JDK1.4 RC is out, here are my Windows settings that make the Java extension work: extension=php_java.dll [Java] java.class.path = c:\php\java\php_java.jar java.home = d:\jdk1.4\jre java.library = d:\jdk1.4\jre\bin\server\jvm.dll I have not tested (yet) whether installing just the JRE works; for servlet support w/ Tomcat you do need JDK since Tomcat needs tools.jar that is not part of JRE.

Java/php bridge? I used printwriter to send data from a java applet to a php document. URL url = new URL("); URLConnection connection = url.openConnection(); connection.setDoOutput(true); PrintWriter out = new PrintWriter(connection.getOutputStream()); out.println(var1); out.println(var2); out.println(var3); out.println(var4); out.flush(); out.close(); BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); String inputLine; while ((inputLine = in.readLine()) != null) System.out.println(inputLine+"\r\n"); in.close(); The problem is that java puts all the data into var1 and doesn't send var2,var3,var4. -----in bla.php $var1; //contains all the data. // $var2,3,4 doesn't exist How can i code the java applet to send var2,var3 and var4?

Installation of PHP's Java module under Win32(Apache/IIS). I install php in "C:\php", firstly I install with "php-4.1.1-installer.exe"(from ), and then unzip the "php-4.1.1-Win32.zip"(from ) to the C:\PHP.(because all the extension dll files are from this zip file, including php_java.dll) I also install my Java v1.3 in "C:\jdk1.3" And My Program require JDBC connection of the Java Program, so I did install also the JDBC driver for MySQL in "c:\JDBC4mysql\mm.mysql.jdbc-1.2c"(from ). About the PHP.ini: 1> You need to set the extension_dir="c:\php\extensions"(directory of all the extensions dll files) 2> Add those lines at the end of php.ini ====== [Java] extension=php_java.dll java.class.path="c:\php\java\php_java.jar;c:\wwwroot; c:\JDBC4mysql\mm.mysql.jdbc-1.2c" java.home="c:\jdk1.3\bin" java.library="c:\jdk1.3\jre\bin\hotspot\jvm.dll" java.library.path="c:\php\extensions" ====== * extension: it is the DLL you wish to load in, here we want to load the java module. * java.class.path: By default, you need to include the "C:\php\java\php_java.jar" for Java & PHP connection, AND those directories that contain the Java class files you wish to run. Here, my program Java classes are in "c:\wwwroot\", and ALSO the JDBC driver classes in "c:\JDBC4mysql\mm.mysql.jdbc-1.2c", because my Program need to import it. * java.home: the bin directory (directory of java.exe) * java.library: jvm.dll is supposed to be under JDK's jre\bin\hotspot, but sometimes it doesn't, try to Find(Start->Find) jvm.dll where it is. * java.library.path: which is the same as the extensions directory.

Invoking java applets from PHP. This might look silly, but I found many people on the net asking how to invoke a java applet from php. Read these notes: (look for the message about servlets). Basically, it's like calling any other URL, so you can use the "file" function. Read also the online documentation about "file". This solution is much easier than many others I have found around the net.

Again about how to call java servlets from php... the above method I described works as long as you don't need to send long strings as parameters and this because they are sent via GET method that cannot handle long strings. So you need to send the parameters via POST, which is not straightforward at all! Infact, you need to open a socket and write php code that sends the call to the servlet as if it came from a form with post method. Look at this url for more information:

Answer to message from [email protected] 13-Feb-2002 12:26 "Java/php bridge? I used printwriter ... " Solution looks like out.write("var1="+URLEncoder.encode(var1)); out.write("&var2="+URLEncoder.encode(var2)); out.write("&var3="+URLEncoder.encode(var3)); etc.

Hello! I have two tips about getting PHP Java to work, hopefully google will pick this up... After you've followed the instructions (building PHP with Java enabled and hacking php.ini) and you get a message like: Fatal error: Cannot instantiate non-existent class: java in (file) on line (line) That means PHP doesn't know what the 'Java' function is. You can confirm that the Java extension isn't loaded by looking at 'phpinfo' and verifying that there is no section titled Java. To fix this you need to edit php.ini and set the 'extensions_dir' and an 'extension' appropriately. On our system it was 'extension_dir = /opt/php/lib/php/extensions/no-debug-non-zts-20020429' and an 'extension = java.so'. All the documentation I found said the extension library should be called 'php_java.so', but our build produced 'java.so', I have no idea why, YMMV. The next error message I ran into was: Fatal error: java.lang.UnsatisfiedLinkError: no php_java in java.library.path in (file) on line (line) Yay! this confirms that the JVM is indeed loading (UnsatisfiedLinkError is totally on the Java side), so relax, you're almost done! What's happening is that the Java class 'net.php.reflect' (a class in php_java.jar that is built by PHP) is trying to execute 'System.loadLibrary("php_java")' and the JVM is unable to find the file named 'libphp_java.so' (or maybe 'php_java.dll' on Windows?). If you ever heard of LD_LIBRARY_PATH, java.library.path is the same thing. The solution has two parts: First making sure the php.ini has a 'java.library.path' (in the '[java]' section) that's pointed at the same directory that 'extension_dir', specifically the directory containing the file 'java.so' (or maybe 'php_java.so' like everyone else). Second, this part is bad IMHO, making a symbolic link from the ''java.so' file to 'libphp_java.so' so that Java's System.loadLibrary method can find what it's looking for (apparently Java prefixes the filename it looks for with "lib"). To make this symbolic link do 'cd' into the extensions directory and run 'ln -s java.so libphp_java.so'. Hope somebody finds this useful!

With latest PHP releases (4.2.1), compilation process doesn't produce a valid name for the Java extension library: I have to rename it to libphp_java.so in order to use it (initial name was java.so). And on my Debian box, I have to add the following lines in my apache init.d script: export LD_LIBRARY_PATH=/usr/local/java/jre/lib/i386 \:/usr/local/java/jre/lib/i386/classic/ It's tricky but now it works well..

--php.ini------------------------- [Java] java.class.path = .\extensions\php_java.jar java.home = c:\java java.library = C:\java\jre\bin\server\jvm.dll java.library.path = c:\apache\php\extensions --system--------------------------- Windows 2000 P + Apache + SUN jdk 1.4.0-beta3 --app path--------------------------- java(C:\java) Apache(C:\apache) PHP(C:\apache\php) ----------------------------- success!


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