   #PHP Manual Function Reference ircg_whois java_last_exception_clear

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XLVII. PHP / Java Integration

Introduction

   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 this Java extension.

   The Java extension 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.

   Warning

   This extension is EXPERIMENTAL. The behaviour of this extension --
   including the names of its functions and anything else documented
   about this extension -- may change without notice in a future release
   of PHP. Use this extension at your own risk.

Requirements

   You need a Java VM installed on your machine to use this extension.

Installation

   To include Java support in your PHP build you must add the option
   --with-java[=DIR] where DIR points to the base install directory of
   your JDK. This extension can only be built as a shared dl. More build
   instructions for this extension can be found in php4/ext/java/README.

     Note to Win32 Users: In order to enable this module on a Windows
     environment with PHP <= 4.0.6, you must copy jvm.dll from the DLL
     folder of the PHP/Win32 binary package to the SYSTEM32 folder of
     your windows machine. (Ex: C:\WINNT\SYSTEM32 or
     C:\WINDOWS\SYSTEM32). For PHP > 4.0.6 you do not need any
     additional dll file.

Runtime Configuration

   The behaviour of these functions is affected by settings in php.ini.

   Table 1. Java configuration options
   Name              Default Changeable
   java.class.path   NULL    PHP_INI_ALL
   java.home         NULL    PHP_INI_ALL
   java.library.path NULL    PHP_INI_ALL
   java.library      JAVALIB PHP_INI_ALL
   For further details and definition of the PHP_INI_* constants see
   ini_set().

Resource Types

   This extension has no resource types defined.

Predefined Constants

   This extension has no constants defined.

Examples

   Example 1. Java Example
   <?php
     // get instance of Java class java.lang.System in PHP
     $system = new Java('java.lang.System');
     // demonstrate property access
     echo 'Java version=' . $system->getProperty('java.version') . '<br
   />';
     echo 'Java vendor=' . $system->getProperty('java.vendor') . '<br
   />';
     echo '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");
     echo $formatter->format(new Java('java.util.Date'));
   ?>

   Example 2. AWT Example
   <?php
     // This example is only intended 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 coerced 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.

Java Servlet SAPI

   The Java Servlet SAPI builds upon the mechanism defined by the Java
   extension 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.

   Table of Contents
   java_last_exception_clear -- Clear last Java exception
   java_last_exception_get -- Get last Java exception
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