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| The Apache Tomcat Servlet/JSP Container | |
| " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 7</font></h1><font face="arial,helvetica,sanserif">Version 7.0.77, Mar 28 2017</font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="./images/asf-logo.svg" align="right" alt="Apache Logo" border="0" style="width: 266px;height: 83px;"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap class="noPrint"><p><strong>Links</strong></p><ul><li><a href="index.html">Docs Home</a></li><li><a href="http://wiki.apache.org/tomcat/FAQ">FAQ</a></li><li><a href="#comments_section">User Comments</a></li></ul><p><strong>User Guide</strong></p><ul><li><a href="introduction.html">1) Introduction</a></li><li><a href="setup.html">2) Setup</a></li><li><a href="appdev/index.html">3) First webapp</a></li><li><a href="deployer-howto.html">4) Deployer</a></li><li><a href="manager-howto.html">5) Manager</a></li><li><a href="realm-howto.html">6) Realms and AAA</a></li><li><a href="security-manager-howto.html">7) Security Manager</a></li><li><a href="jndi-resources-howto.html">8) JNDI Resources</a></li><li><a href="jndi-datasource-examples-howto.html">9) JDBC DataSources</a></li><li><a href="class-loader-howto.html">10) Classloading</a></li><li><a href="jasper-howto.html">11) JSPs</a></li><li><a href="ssl-howto.html">12) SSL/TLS</a></li><li><a href="ssi-howto.html">13) SSI</a></li><li><a href="cgi-howto.html">14) CGI</a></li><li><a href="proxy-howto.html">15) Proxy Support</a></li><li><a href="mbeans-descriptors-howto.html">16) MBeans Descriptors</a></li><li><a href="default-servlet.html">17) Default Servlet</a></li><li><a href="cluster-howto.html">18) Clustering</a></li><li><a href="balancer-howto.html">19) Load Balancer</a></li><li><a href="connectors.html">20) Connectors</a></li><li><a href="monitoring.html">21) Monitoring and Management</a></li><li><a href="logging.html">22) Logging</a></li><li><a href="apr.html">23) APR/Native</a></li><li><a href="virtual-hosting-howto.html">24) Virtual Hosting</a></li><li><a href="aio.html">25) Advanced IO</a></li><li><a href="extras.html">26) Additional Components</a></li><li><a href="maven-jars.html">27) Mavenized</a></li><li><a href="security-howto.html">28) Security Considerations</a></li><li><a href="windows-service-howto.html">29) Windows Service</a></li><li><a href="windows-auth-howto.html">30) Windows Authentication</a></li><li><a href="jdbc-pool.html">31) Tomcat's JDBC Pool</a></li><li><a href="web-socket-howto.html">32) WebSocket</a></li></ul><p><strong>Reference</strong></p><ul><li><a href="RELEASE-NOTES.txt">Release Notes</a></li><li><a href="config/index.html">Configuration</a></li><li><a href="api/index.html">Tomcat Javadocs</a></li><li><a href="servletapi/index.html">Servlet Javadocs</a></li><li><a href="jspapi/index.html">JSP 2.2 Javadocs</a></li><li><a href="elapi/index.html">EL 2.2 Javadocs</a></li><li><a href="websocketapi/index.html">WebSocket 1.1 Javadocs</a></li><li><a href="http://tomcat.apache.org/connectors-doc/">JK 1.2 Documentation</a></li></ul><p><strong>Apache Tomcat Development</strong></p><ul><li><a href="building.html">Building</a></li><li><a href="changelog.html">Changelog</a></li><li><a href="http://wiki.apache.org/tomcat/TomcatVersions">Status</a></li><li><a href="developers.html">Developers</a></li><li><a href="architecture/index.html">Architecture</a></li><li><a href="funcspecs/index.html">Functional Specs.</a></li><li><a href="tribes/introduction.html">Tribes</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left" id="mainBody"><h1>Jasper 2 JSP Engine How To</h1><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Table of Contents"><!--()--></a><a name="Table_of_Contents"><strong>Table of Contents</strong></a></font></td></tr><tr><td><blockquote> | |
| <ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Configuration">Configuration</a></li><li><a href="#Known_issues">Known issues</a></li><li><a href="#Production_Configuration">Production Configuration</a></li><li><a href="#Web_Application_Compilation">Web Application Compilation</a></li><li><a href="#Optimisation">Optimisation</a></li></ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>Tomcat 7.0 uses the Jasper 2 JSP Engine to implement | |
| the <a href="http://wiki.apache.org/tomcat/Specifications">JavaServer Pages 2.2</a> | |
| specification.</p> | |
| <p>Jasper 2 has been redesigned to significantly improve performance over | |
| the original Jasper. In addition to general code improvements the following | |
| changes were made:</p> | |
| <ul> | |
| <li><strong>JSP Custom Tag Pooling</strong> - The java objects instantiated | |
| for JSP Custom Tags can now be pooled and reused. This significantly boosts | |
| the performance of JSP pages which use custom tags.</li> | |
| <li><strong>Background JSP compilation</strong> - If you make a change to | |
| a JSP page which had already been compiled Jasper 2 can recompile that | |
| page in the background. The previously compiled JSP page will still be | |
| available to serve requests. Once the new page has been compiled | |
| successfully it will replace the old page. This helps improve availability | |
| of your JSP pages on a production server.</li> | |
| <li><strong>Recompile JSP when included page changes</strong> - Jasper 2 | |
| can now detect when a page included at compile time from a JSP has changed | |
| and then recompile the parent JSP.</li> | |
| <li><strong>JDT used to compile JSP pages</strong> - The | |
| Eclipse JDT Java compiler is now used to perform JSP java source code | |
| compilation. This compiler loads source dependencies from the container | |
| classloader. Ant and javac can still be used.</li> | |
| </ul> | |
| <p>Jasper is implemented using the servlet class | |
| <code>org.apache.jasper.servlet.JspServlet</code>.</p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Configuration"><strong>Configuration</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>By default Jasper is configured for use when doing web application | |
| development. See the section <a href="#Production_Configuration"> | |
| Production Configuration</a> for information on configuring Jasper | |
| for use on a production Tomcat server.</p> | |
| <p>The servlet which implements Jasper is configured using init parameters | |
| in your global <code>$CATALINA_BASE/conf/web.xml</code>. | |
| </p> | |
| <ul> | |
| <li><strong>checkInterval</strong> - If development is false and checkInterval | |
| is greater than zero, background compiles are enabled. checkInterval is the time | |
| in seconds between checks to see if a JSP page (and its dependent files) needs | |
| to be recompiled. Default <code>0</code> seconds.</li> | |
| <li><strong>classdebuginfo</strong> - Should the class file be compiled with | |
| debugging information? <code>true</code> or <code>false</code>, default | |
| <code>true</code>. | |
| </li> | |
| <li><strong>classpath</strong> - Defines the class path to be used to compile | |
| the generated servlets. This parameter only has an effect if the ServletContext | |
| attribute org.apache.jasper.Constants.SERVLET_CLASSPATH is not set. This | |
| attribute is always set when Jasper is used within Tomcat. By default the | |
| classpath is created dynamically based on the current web application.</li> | |
| <li><strong>compiler</strong> - Which compiler Ant should use to compile JSP | |
| pages. The valid values for this are the same as for the compiler attribute of | |
| Ant's | |
| <a href="http://ant.apache.org/manual/Tasks/javac.html#compilervalues">javac</a> | |
| task. If the value is not set, then the default Eclipse JDT Java compiler will | |
| be used instead of using Ant. There is no default value. If this attribute is | |
| set then <code>setenv.[sh|bat]</code> should be used to add | |
| <code>ant.jar</code>, <code>ant-launcher.jar</code> and <code>tools.jar</code> | |
| to the <code>CLASSPATH</code> environment variable.</li> | |
| <li><strong>compilerSourceVM</strong> - What JDK version are the source files | |
| compatible with? (Default value: <code>1.6</code>)</li> | |
| <li><strong>compilerTargetVM</strong> - What JDK version are the generated files | |
| compatible with? (Default value: <code>1.6</code>)</li> | |
| <li><strong>development</strong> - Is Jasper used in development mode? If true, | |
| the frequency at which JSPs are checked for modification may be specified via | |
| the modificationTestInterval parameter.<code>true</code> or <code>false</code>, | |
| default <code>true</code>.</li> | |
| <li><strong>displaySourceFragment</strong> - Should a source fragment be | |
| included in exception messages? <code>true</code> or <code>false</code>, | |
| default <code>true</code>.</li> | |
| <li><strong>dumpSmap</strong> - Should the SMAP info for JSR45 debugging be | |
| dumped to a file? <code>true</code> or <code>false</code>, default | |
| <code>false</code>. <code>false</code> if suppressSmap is true.</li> | |
| <li><strong>enablePooling</strong> - Determines whether tag handler pooling is | |
| enabled. This is a compilation option. It will not alter the behaviour of JSPs | |
| that have already been compiled. <code>true</code> or <code>false</code>, | |
| default <code>true</code>. | |
| </li> | |
| <li><strong>engineOptionsClass</strong> - Allows specifying the Options class | |
| used to configure Jasper. If not present, the default EmbeddedServletOptions | |
| will be used. This option is ignored if running under a SecurityManager. | |
| </li> | |
| <li><strong>errorOnUseBeanInvalidClassAttribute</strong> - Should Jasper issue | |
| an error when the value of the class attribute in an useBean action is not a | |
| valid bean class? <code>true</code> or <code>false</code>, default | |
| <code>true</code>.</li> | |
| <li><strong>fork</strong> - Have Ant fork JSP page compiles so they are | |
| performed in a separate JVM from Tomcat? <code>true</code> or | |
| <code>false</code>, default <code>true</code>.</li> | |
| <li><strong>genStringAsCharArray</strong> - Should text strings be generated as char | |
| arrays, to improve performance in some cases? Default <code>false</code>.</li> | |
| <li><strong>ieClassId</strong> - The class-id value to be sent to Internet | |
| Explorer when using <jsp:plugin> tags. Default | |
| <code>clsid:8AD9C840-044E-11D1-B3E9-00805F499D93</code>.</li> | |
| <li><strong>javaEncoding</strong> - Java file encoding to use for generating | |
| java source files. Default <code>UTF8</code>.</li> | |
| <li><strong>keepgenerated</strong> - Should we keep the generated Java source | |
| code for each page instead of deleting it? <code>true</code> or | |
| <code>false</code>, default <code>true</code>.</li> | |
| <li><strong>mappedfile</strong> - Should we generate static content with one | |
| print statement per input line, to ease debugging? | |
| <code>true</code> or <code>false</code>, default <code>true</code>.</li> | |
| <li><strong>maxLoadedJsps</strong> - The maximum number of JSPs that will be | |
| loaded for a web application. If more than this number of JSPs are loaded, the | |
| least recently used JSPs will be unloaded so that the number of JSPs loaded at | |
| any one time does not exceed this limit. A value of zero or less indicates no | |
| limit. Default <code>-1</code></li> | |
| <li><strong>jspIdleTimeout</strong> - The amount of time in seconds a JSP can be | |
| idle before it is unloaded. A value of zero or less indicates never unload. | |
| Default <code>-1</code></li> | |
| <li><strong>modificationTestInterval</strong> - Causes a JSP (and its dependent | |
| files) to not be checked for modification during the specified time interval | |
| (in seconds) from the last time the JSP was checked for modification. A value of | |
| 0 will cause the JSP to be checked on every access. Used in development mode | |
| only. Default is <code>4</code> seconds.</li> | |
| <li><strong>recompileOnFail</strong> - If a JSP compilation fails should the | |
| modificationTestInterval be ignored and the next access trigger a re-compilation | |
| attempt? Used in development mode only and is disabled by default as compilation | |
| may be expensive and could lead to excessive resource usage.</li> | |
| <li><strong>scratchdir</strong> - What scratch directory should we use when | |
| compiling JSP pages? Default is the work directory for the current web | |
| application. This option is ignored if running under a SecurityManager.</li> | |
| <li><strong>suppressSmap</strong> - Should the generation of SMAP info for JSR45 | |
| debugging be suppressed? <code>true</code> or <code>false</code>, default | |
| <code>false</code>.</li> | |
| <li><strong>trimSpaces</strong> - Should white spaces in template text between | |
| actions or directives be trimmed ?, default <code>false</code>.</li> | |
| <li><strong>xpoweredBy</strong> - Determines whether X-Powered-By response | |
| header is added by generated servlet. <code>true</code> or <code>false</code>, | |
| default <code>false</code>.</li> | |
| <li><strong>quoteAttributeEL</strong> - When EL is used in an attribute value | |
| on a JSP page, should the rules for quoting of attributes described in JSP.1.6 | |
| be applied to the expression? <code>true</code> or <code>false</code>, default | |
| <code>true</code>.</li> | |
| </ul> | |
| <p>The Java compiler from Eclipse JDT in included as the default compiler. It is | |
| an advanced Java compiler which will load all dependencies from the Tomcat class | |
| loader, which will help tremendously when compiling on large installations with | |
| tens of JARs. On fast servers, this will allow sub-second recompilation cycles | |
| for even large JSP pages.</p> | |
| <p>Apache Ant, which was used in previous Tomcat releases, can be used instead | |
| of the new compiler by configuring the compiler attribute as explained above. | |
| </p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Known issues"><!--()--></a><a name="Known_issues"><strong>Known issues</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>As described in | |
| <a href="https://bz.apache.org/bugzilla/show_bug.cgi?id=39089"> | |
| bug 39089</a>, a known JVM issue, | |
| <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6294277"> | |
| bug 6294277</a>, may cause a | |
| <code>java.lang.InternalError: name is too long to represent</code> exception | |
| when compiling very large JSPs. If this is observed then it may be worked around | |
| by using one of the following: | |
| </p> | |
| <ul> | |
| <li>reduce the size of the JSP</li> | |
| <li>disable SMAP generation and JSR-045 support by setting | |
| <code>suppressSmap</code> to <code>true</code>.</li> | |
| </ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Production Configuration"><!--()--></a><a name="Production_Configuration"><strong>Production Configuration</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>The main JSP optimization which can be done is precompilation of JSPs. | |
| However, this might not be possible (for example, when using the | |
| jsp-property-group feature) or practical, in which case the configuration of the | |
| Jasper servlet becomes critical.</p> | |
| <p>When using Jasper 2 in a production Tomcat server you should consider making | |
| the following changes from the default configuration.</p> | |
| <ul> | |
| <li><strong>development</strong> - To disable on access checks for JSP | |
| pages compilation set this to <code>false</code>.</li> | |
| <li><strong>genStringAsCharArray</strong> - To generate slightly more efficient | |
| char arrays, set this to <code>true</code>.</li> | |
| <li><strong>modificationTestInterval</strong> - If development has to be set to | |
| <code>true</code> for any reason (such as dynamic generation of JSPs), setting | |
| this to a high value will improve performance a lot.</li> | |
| <li><strong>trimSpaces</strong> - To remove useless bytes from the response, | |
| set this to <code>true</code>.</li> | |
| </ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Web Application Compilation"><!--()--></a><a name="Web_Application_Compilation"><strong>Web Application Compilation</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>Using Ant is the preferred way to compile web applications using JSPC. Note | |
| that when pre-compiling JSPs, SMAP information will only be included in the | |
| final classes if suppressSmap is false and compile is true. | |
| Use the script given below (a similar script is included in the "deployer" | |
| download) to precompile a webapp: | |
| </p> | |
| <div class="codeBox"><pre><code><project name="Webapp Precompilation" default="all" basedir="."> | |
| <import file="${tomcat.home}/bin/catalina-tasks.xml"/> | |
| <target name="jspc"> | |
| <jasper | |
| validateXml="false" | |
| uriroot="${webapp.path}" | |
| webXmlFragment="${webapp.path}/WEB-INF/generated_web.xml" | |
| outputDir="${webapp.path}/WEB-INF/src" /> | |
| </target> | |
| <target name="compile"> | |
| <mkdir dir="${webapp.path}/WEB-INF/classes"/> | |
| <mkdir dir="${webapp.path}/WEB-INF/lib"/> | |
| <javac destdir="${webapp.path}/WEB-INF/classes" | |
| optimize="off" | |
| debug="on" failonerror="false" | |
| srcdir="${webapp.path}/WEB-INF/src" | |
| excludes="**/*.smap"> | |
| <classpath> | |
| <pathelement location="${webapp.path}/WEB-INF/classes"/> | |
| <fileset dir="${webapp.path}/WEB-INF/lib"> | |
| <include name="*.jar"/> | |
| </fileset> | |
| <pathelement location="${tomcat.home}/lib"/> | |
| <fileset dir="${tomcat.home}/lib"> | |
| <include name="*.jar"/> | |
| </fileset> | |
| <fileset dir="${tomcat.home}/bin"> | |
| <include name="*.jar"/> | |
| </fileset> | |
| </classpath> | |
| <include name="**" /> | |
| <exclude name="tags/**" /> | |
| </javac> | |
| </target> | |
| <target name="all" depends="jspc,compile"> | |
| </target> | |
| <target name="cleanup"> | |
| <delete> | |
| <fileset dir="${webapp.path}/WEB-INF/src"/> | |
| <fileset dir="${webapp.path}/WEB-INF/classes/org/apache/jsp"/> | |
| </delete> | |
| </target> | |
| </project></code></pre></div> | |
| <p> | |
| The following command line can be used to run the script | |
| (replacing the tokens with the Tomcat base path and the path to the webapp | |
| which should be precompiled): | |
| </p> | |
| <div class="codeBox"><pre><code>$ANT_HOME/bin/ant -Dtomcat.home=<$TOMCAT_HOME> -Dwebapp.path=<$WEBAPP_PATH></code></pre></div> | |
| <p> | |
| Then, the declarations and mappings for the servlets which were generated | |
| during the precompilation must be added to the web application deployment | |
| descriptor. Insert the <code>${webapp.path}/WEB-INF/generated_web.xml</code> | |
| at the right place inside the <code>${webapp.path}/WEB-INF/web.xml</code> file. | |
| Restart the web application (using the manager) and test it to verify it is | |
| running fine with precompiled servlets. An appropriate token placed in the | |
| web application deployment descriptor may also be used to automatically | |
| insert the generated servlet declarations and mappings using Ant filtering | |
| capabilities. This is actually how all the webapps distributed with Tomcat | |
| are automatically compiled as part of the build process. | |
| </p> | |
| <p> | |
| At the jasper task you can use the option <code>addWebXmlMappings</code> for | |
| automatic merge the <code>${webapp.path}/WEB-INF/generated_web.xml</code> | |
| with the current web application deployment descriptor at | |
| <code>${webapp.path}/WEB-INF/web.xml</code>. When you want to use Java 6 | |
| features inside your jsp's, add the following javac compiler task attributes: | |
| <code>source="1.6" target="1.6"</code>. For live | |
| applications you can also compile with <code>optimize="on"</code> and | |
| without debug info <code>debug="off"</code>. | |
| </p> | |
| <p> | |
| When you don't want to stop the jsp generation at first jsp syntax error, use | |
| <code>failOnError="false"</code>and with | |
| <code>showSuccess="true"</code> all successful <i>jsp to java</i> | |
| generation are printed out. Sometimes it is very helpful, when you cleanup the | |
| generate java source files at <code>${webapp.path}/WEB-INF/src</code> | |
| and the compile jsp servlet classes at | |
| <code>${webapp.path}/WEB-INF/classes/org/apache/jsp</code>. | |
| </p> | |
| <p><strong>Hints:</strong></p> | |
| <ul> | |
| <li> When you switch to another Tomcat release, then regenerate and recompile | |
| your jsp's with the new Tomcat version.</li> | |
| <li>Use java system property at server runtime to disable PageContext pooling | |
| <code>org.apache.jasper.runtime.JspFactoryImpl.USE_POOL=false</code>. | |
| and limit the buffering with | |
| <code>org.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER=true</code>. Note | |
| that changing from the defaults may affect performance, but it will vary | |
| depending on the application.</li> | |
| </ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Optimisation"><strong>Optimisation</strong></a></font></td></tr><tr><td><blockquote> | |
| <p> | |
| There are a number of extension points provided within Jasper that enable the | |
| user to optimise the behaviour for their environment. | |
| </p> | |
| <p> | |
| The first of these extension points is the tag plug-in mechanism. This allows | |
| alternative implementations of tag handlers to be provided for a web application | |
| to use. Tag plug-ins are registered via a <code>tagPlugins.xml</code> file | |
| located under <code>WEB-INF</code>. A sample plug-in for the JSTL is included | |
| with Jasper. | |
| </p> | |
| <p> | |
| The second extension point is the Expression Language interpreter. Alternative | |
| interpreters may be configured through the <code>ServletContext</code>. See the | |
| <code>ELInterpreterFactory</code> javadoc for details of how to configure an | |
| alternative EL interpreter. | |
| </p> | |
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