Apache Tomcat 5.5 Servlet/JSP 容器 - Jasper 2 JSP Engine How To

Using Ant is the preferred way to compile web applications using JSPC. Use the script given below (a similar script is included in the "deployer" download) to precompile a webapp:

<project name="Webapp Precompilation" default="all" basedir="."> 

  <target name="jspc"> 

    <taskdef classname="org.apache.jasper.JspC" name="jasper2" > 
      <classpath id="jspc.classpath"> 
        <pathelement location="${java.home}/../lib/tools.jar"/> 
        <fileset dir="${tomcat.home}/bin"> 
          <include name="*.jar"/> 
        </fileset> 
        <fileset dir="${tomcat.home}/server/lib"> 
          <include name="*.jar"/> 
        </fileset> 
        <fileset dir="${tomcat.home}/common/lib"> 
          <include name="*.jar"/> 
        </fileset> 
      </classpath> 
    </taskdef> 

    <jasper2 
             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="${tomcat.home}/common/classes"/>
        <fileset dir="${tomcat.home}/common/lib">
          <include name="*.jar"/>
        </fileset>
        <pathelement location="${tomcat.home}/shared/classes"/>
        <fileset dir="${tomcat.home}/shared/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>

下面的命令行可以用来运行这个script(用Tomcat基础路径和指向应该被预编译的webapp的路径来代替那些记号)。

然后,对于在预编译过程中产生的servlets的声明和映射必须被加入到网络程序部署描述符里去。把${webapp.path}/WEB-INF/generated_web.xml插入到${webapp.path}/WEB-INF/web.xml文件应该被放置的地方。重新启动web程序(使用the manager)，并测试它以验证预编译过的servlets能正常运行。网络程序部署描述符里适当的标记(token)也可以被用来通过Ant过滤功能自动插入所产生servlets声明和映射。事实上这就是Tomcat发布的所有webapps作为build过程的一部分是怎样自动被编译的。

At the jasper2 task you can use the option addWebXmlMappings for automatic merge the ${webapp.path}/WEB-INF/generated_web.xml with the current web application deployment descriptor at ${webapp.path}/WEB-INF/web.xml. When you want to use Java 5 feature inside your jsp's, add the following javac compiler task attributes: source="1.5" target="1.5". For live application you can also compile with optimize="on" and without debug info debug="off".

When you don't want to stop the jsp generation at first jsp syntax error, use failOnError="false"and with showSuccess="true" all successfull jsp to java generation are printed out. Sometimes it is very helpfull, when you cleanup the generate java source files at ${webapp.path}/WEB-INF/src and the compile jsp servlet classes at ${webapp.path}/WEB-INF/classes/org/apache/jsp.