mirror of
https://github.com/sigmasternchen/php-doc-en
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7839d91186
removing the others git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@78562 c90b9560-bf6c-de11-be94-00142212c4b1
258 lines
8.3 KiB
XML
258 lines
8.3 KiB
XML
<!-- D O N O T E D I T T H I S F I L E ! ! !
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it is still here for historical reasons only
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(as translators may need to check old revision diffs)
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if you want to change things documented in this file
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you should now edit the files found under en/reference
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instead -->
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<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.17 $ -->
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<reference id="ref.java">
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<title>Java</title>
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<titleabbrev>PHP / Java Integration</titleabbrev>
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<partintro>
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<para>
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There are two possible ways to bridge PHP and Java: you can either
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integrate PHP into a Java Servlet environment, which is the more
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stable and efficient solution, or integrate Java support into PHP.
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The former is provided by a SAPI module that interfaces with the
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Servlet server, the latter by the Java extension.
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</para>
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<para>
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PHP 4 ext/java provides a simple and effective means for creating and
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invoking methods on Java objects from PHP. The JVM is created using JNI,
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and everything runs in-process. Build instructions for ext/java can be
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found in <filename>php4/ext/java/README</filename>.
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<example>
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<title>Java Example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// get instance of Java class java.lang.System in PHP
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$system = new Java('java.lang.System');
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// demonstrate property access
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print 'Java version='.$system->getProperty('java.version').' <br>';
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print 'Java vendor=' .$system->getProperty('java.vendor').' <br>';
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print 'OS='.$system->getProperty('os.name').' '.
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$system->getProperty('os.version').' on '.
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$system->getProperty('os.arch').' <br>';
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// java.util.Date example
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$formatter = new Java('java.text.SimpleDateFormat',
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"EEEE, MMMM dd, yyyy 'at' h:mm:ss a zzzz");
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print $formatter->format(new Java('java.util.Date'));
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title>AWT Example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// This example is only intented to be run as a CGI.
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$frame = new Java('java.awt.Frame', 'PHP');
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$button = new Java('java.awt.Button', 'Hello Java World!');
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$frame->add('North', $button);
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$frame->validate();
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$frame->pack();
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$frame->visible = True;
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$thread = new Java('java.lang.Thread');
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$thread->sleep(10000);
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$frame->dispose();
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?>
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]]>
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</programlisting>
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</example>
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Notes:
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<itemizedlist>
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<listitem>
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<simpara>
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<literal>new Java()</literal> will create an instance of a class if
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a suitable constructor is available. If no parameters are passed and
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the default constructor is useful as it provides access to classes
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like <literal>java.lang.System</literal> which expose most of their
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functionallity through static methods.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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Accessing a member of an instance will first look for bean properties
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then public fields. In other words, <literal>print $date.time</literal>
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will first attempt to be resolved as <literal>$date.getTime()</literal>,
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then as <literal>$date.time</literal>.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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Both static and instance members can be accessed on an object with
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the same syntax. Furthermore, if the java object is of type
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<literal>java.lang.Class</literal>, then static members of the class
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(fields and methods) can be accessed.
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</simpara>
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</listitem>
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<listitem>
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<para>
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Exceptions raised result in PHP warnings, and &null; results. The
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warnings may be eliminated by prefixing the method call with an
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"@" sign. The following APIs may be used to retrieve and reset
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the last error:
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<itemizedlist>
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<listitem><simpara><function>java_last_exception_get</function></simpara></listitem>
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<listitem><simpara><function>java_last_exception_clear</function></simpara></listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<simpara>
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Overload resolution is in general a hard problem given the
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differences in types between the two languages. The PHP Java
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extension employs a simple, but fairly effective, metric for
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determining which overload is the best match.
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</simpara>
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<simpara>
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Additionally, method names in PHP are not case sensitive, potentially
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increasing the number of overloads to select from.
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</simpara>
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<simpara>
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Once a method is selected, the parameters are cooerced if necessary,
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possibly with a loss of data (example: double precision floating point
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numbers will be converted to boolean).
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<!-- FIXME Why aren't java-doubles converted to PHP-floats? Is this
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correct? -->
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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In the tradition of PHP, arrays and hashtables may pretty much
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be used interchangably. Note that hashtables in PHP may only be
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indexed by integers or strings; and that arrays of primitive types
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in Java can not be sparse. Also note that these constructs are
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passed by value, so may be expensive in terms of memory and time.
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</simpara>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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sapi/servlet builds upon the mechanism defined by ext/java to enable
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the entire PHP processor to be run as a servlet. The primary advanatage
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of this from a PHP perspective is that web servers which support servlets
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typically take great care in pooling and reusing JVMs. Build instructions
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for the Servlet SAPI module can be found in
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<filename>php4/sapi/README</filename>.
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Notes:
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<itemizedlist>
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<listitem>
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<simpara>
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While this code is intended to be able to run on any servlet engine,
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it has only been tested on Apache's Jakarta/tomcat to date. Bug
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reports, success stories and/or patches required to get this code
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to run on other engines would be appreciated.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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PHP has a habit of changing the working directory. sapi/servlet will
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eventually change it back, but while PHP is running the servlet engine
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may not be able to load any classes from the CLASSPATH which are
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specified using a relative directory syntax, or find the work directory
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used for administration and JSP compilation tasks.
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</simpara>
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</listitem>
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</itemizedlist>
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</para>
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</partintro>
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<refentry id="function.java-last-exception-clear">
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<refnamediv>
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<refname>java_last_exception_clear</refname>
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<refpurpose>Clear last Java exception</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>void</type><methodname>java_last_exception_clear</methodname>
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<void/>
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</methodsynopsis>
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</refsect1>
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</refentry>
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<refentry id="function.java-last-exception-get">
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<refnamediv>
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<refname>java_last_exception_get</refname>
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<refpurpose>Get last Java exception</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>exception</type><methodname>java_last_exception_get</methodname>
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<void/>
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</methodsynopsis>
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<para>
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The following example demonstrates the usage of Java's exception
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handler from within PHP:
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<example>
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<title>Java exception handler</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$stack = new Java('java.util.Stack');
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$stack->push(1);
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// This should succeed
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$result = $stack->pop();
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$ex = java_last_exception_get();
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if (!$ex) print "$result\n";
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// This should fail (error suppressed by @)
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$result = @$stack->pop();
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$ex = java_last_exception_get();
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if ($ex) print $ex->toString();
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// Clear last exception
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java_last_exception_clear();
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?>
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]]>
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</programlisting>
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</example>
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</para>
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</refsect1>
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</refentry>
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</reference>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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