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Difference between revisions of "Jetty/Howto/Configure JSP"
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The JSP engine has many configuration parameters. Some parameters affect only precompilation, and some affect runtime recompilation checking. Parameters also differ between the 2.0 and 2.1 release of the JSP engine. This page lists the configuration parameters, their meanings and their default settings. | The JSP engine has many configuration parameters. Some parameters affect only precompilation, and some affect runtime recompilation checking. Parameters also differ between the 2.0 and 2.1 release of the JSP engine. This page lists the configuration parameters, their meanings and their default settings. | ||
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− | {{important|Be careful|For all of the parameters below, if the value you set doesn't take effect, try using all lower case instead of camel case, as JSP is inconsistent in its parameter naming strategy. | + | {{important|Be careful| |
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+ | * When you use JSP, you must use a JDK; JRE is insufficient for work with JSP files. Configure your environment to have JAVA_HOME point to the JDK, not the JRE. | ||
+ | * For all of the parameters below, if the value you set doesn't take effect, try using all lower case instead of camel case, as JSP is inconsistent in its parameter naming strategy. | ||
+ | * Be aware that for JDK1.6, the default for ''keepgenerated'' is ''false'', therefore .java files will only be left after compilation if a compilation error occurs.}} | ||
Revision as of 15:28, 12 October 2011
Contents
Introduction
The JSP engine has many configuration parameters. Some parameters affect only precompilation, and some affect runtime recompilation checking. Parameters also differ between the 2.0 and 2.1 release of the JSP engine. This page lists the configuration parameters, their meanings and their default settings.
Understanding JSP 2.1 Parameters
init param | Description | Default | webdefault.xml |
---|---|---|---|
development | If development=true, recompilation checks are made on each request. See also modificationTestInterval. | TRUE | - |
fork | Should Ant fork its java compiles of JSP pages? | TRUE | FALSE |
keepgenerated | Do you want to keep the generated Java files around? | FALSE | - |
saveByteCode | If class files are generated as byte arrays, should they be saved to disk at the end of compilations? | FALSE | - |
trimSpaces | Should white spaces between directives or actions be trimmed? | FALSE | - |
enablePooling | Determines whether tag handler pooling is enabled. | TRUE | - |
mappedFile | Support for mapped Files. Generates a servlet that has a print statement per line of the JSP file. | TRUE | - |
sendErrorToClient | If false, stack traces, etc., are sent to std error instead of the client's browser. | FALSE | - |
classdebuginfo | Include debugging info in class file. | TRUE | - |
checkInterval | Interval in seconds between background recompile checks. Only relevant if development=false. | 0 | - |
suppressSmap | Generation of SMAP info for JSR45 debugging. | FALSE | - |
dumpSmap | Dump SMAP JSR45 info to a file. | FALSE | - |
genStrAsCharArray | Option for generating Strings. | FALSE | - |
genStrAsByteArray | Option for generating Strings. | TRUE | - |
defaultBufferNone | FALSE | - | |
errorOnUseBeanInvalidClassAttribute | FALSE | - | |
scratchDir |
Directory where servlets are generated. Jetty sets this value according to the [/display/JETTY/Temporary+Directories work dir] settings for the webapp. |
- | - |
compiler | Determined at runtime. For Jetty this is the eclipse jdt compiler. | ||
compilerTargetVM | Target vm to compile for. | 1.5 | - |
compilerSourceVM | Sets source compliance level for the jdt compiler. | 1.5 | - |
javaEncoding | Pass through the encoding to use for the compilation. | UTF8 | - |
modificationTestInterval | If development=true, interval between recompilation checks, triggered by a request. | 0 | - |
xpoweredBy | Generate an X-Powered-By response header. | FALSE | FALSE |
usePrecompiled/use-precompiled | FALSE | - | |
validating/enableTldValidation | Whether or not to validate tag files against the schema. | FALSE | |
reload-interval | If reload-interval=0, then no runtime checking of JSP, otherwise sets the checking interval for both development=true and development=false. | ||
initial-capacity/initialCapacity | The initial capacity of the hash maps mapping the name of the JSP to class and JSP file. |
Much confusion generally ensues about the development, checkInterval and modificationTestInterval parameters and JSP runtime recompilation. Here is a factoring out of the various options:
- Check the JSP files for possible recompilation on every request:
<init-param> <param-name>development></param-name> <param-value>true></param-value> </init-param>
- Only check approximately every N seconds, where a request will trigger the time-lapse calculation. This example checks every 60 seconds:
<init-param> <param-name>development></param-name> <param-value>true></param-value> </init-param> <init-param> <param-name>modificationTestInterval></param-name> <param-value>60></param-value> </init-param>
- Do no checking whatsoever, but still compile the JSP on the very first hit. (Note: this reload-interval parameter is shorthand for a development=false and checkInterval=0 combination):
<init-param> <param-name>reload-interval></param-name> <param-value>-1></param-value> </init-param>
- Don't do any request-time checking, but instead start a background thread to do checks every N seconds. (This example checks every 60 seconds):
<init-param> <param-name>development></param-name> <param-value>false></param-value> </init-param> <init-param> <param-name>checkInterval></param-name> <param-value>60></param-value> </init-param>
Modifying the Configuration
There are several options for modifying the Jasper JSP servlet configuration.
Overriding webdefault.xml
You can make a copy of the webdefault.xml shipped with Jetty, apply your changes, and use it instead of the shipped version. The example below shows how to do this when using the Jetty Maven plugin.
<plugin> <groupId>org.mortbay.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <configuration> <webAppConfig> <defaultsDescriptor>src/main/resources/webdefault.xml</defaultsDescriptor> </webAppConfig> <connectors> ..
If you're using Jetty standalone, and you want to change the JSP settings for just one or a few of your webapps, then copy the $JETTY_HOME/etc/webdefault.xml file somewhere, modify it, and then use a context xml file to set this file as the webdefaults for your webapp. Here's a snippet:
<Configure class=>"org.eclipse.jetty.webapp.WebAppContext"> <Set name=>"contextPath">/foo</Set> <Set name=>"war"><SystemProperty name=>"jetty.home" >default=>"."/>/webapps/foobar.war</Set> <Set name=>"defaultsDescriptor">/home/smith/dev/webdefault.xml</Set> </Configure>
If you want to change the JSP settings for all of the webapps, then edit the $JETTY_HOME/etc/webdefaults.xml file directly instead.
Configuring the JSP Servlet in web.xml
Another option is to add an entry for the Jasper JSP servlet to the web.xml file of your webapp. You can use the entry in webdefault.xml as a starting point.
<servlet id=>"jsp"> <servlet-name>jsp</servlet-name> <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class> <init-param> <param-name>logVerbosityLevel</param-name> <param-value>DEBUG</param-value> </init-param> <init-param> <param-name>fork</param-name> <param-value>>false</param-value> </init-param> <init-param> <param-name>keepgenerated</param-name> <param-value>>true</param-value> </init-param> ... <load-on-startup>0</load-on-startup> </servlet> <servlet-mapping> <servlet-name>jsp</servlet-name> <url-pattern>*.jsp</url-pattern> <url-pattern>*.jspf</url-pattern> <url-pattern>*.jspx</url-pattern> <url-pattern>*.xsp</url-pattern> <url-pattern>*.JSP</url-pattern> <url-pattern>*.JSPF</url-pattern> <url-pattern>*.JSPX</url-pattern> <url-pattern>*.XSP</url-pattern> </servlet-mapping> <servlet id=>"my-servlet"> <servlet-name>myServlet</servlet-name> <servlet-class>com.acme.servlet.MyServlet</servlet-class> ...