我成功实现了预编译,可以在服务器启动时(无需使用JspC,因此构建文件更简单)和构建时(服务器启动时间更快)进行。我动态地注册生成的servlet,因此如果您添加/删除JSP,则不必手动更改任何文件。
在服务器启动时
使用
ServletRegistration.Dynamic
为每个JSP注册一个
JSP_SERVLET_CLASS
Servlet。
使用
initParameter
jspFile
设置JSP文件名(
ref)。
例如,在ServletContextInitializer
(参考资料)中使用SpringBoot:
@Bean
public ServletContextInitializer preCompileJspsAtStartup() {
return servletContext -> {
getDeepResourcePaths(servletContext, "/WEB-INF/jsp/").forEach(jspPath -> {
log.info("Registering JSP: {}", jspPath);
ServletRegistration.Dynamic reg = servletContext.addServlet(jspPath, Constants.JSP_SERVLET_CLASS);
reg.setInitParameter("jspFile", jspPath);
reg.setLoadOnStartup(99);
reg.addMapping(jspPath);
});
};
}
private static Stream<String> getDeepResourcePaths(ServletContext servletContext, String path) {
return (path.endsWith("/")) ? servletContext.getResourcePaths(path).stream().flatMap(p -> getDeepResourcePaths(servletContext, p))
: Stream.of(path);
}
在构建时
使用JspC(参考文献)为每个JSP生成Java源文件,并使用它们的Servlet映射生成web.xml。
然后使用Tomcat的WebXmlParser
解析web.xml
,并将其与ServletContext
注册,例如对于SpringBoot:
@Value("classpath:precompiled-jsp-web.xml")
private Resource precompiledJspWebXml;
@Bean
public ServletContextInitializer registerPreCompiledJsps() {
return servletContext -> {
WebXmlParser parser = new WebXmlParser(false, true, true);
try (InputStream is = precompiledJspWebXml.getInputStream()) {
WebXml webXml = new WebXml();
boolean success = parser.parseWebXml(new InputSource(is), webXml, false);
if (!success) {
throw new RuntimeException("Error parsing Web XML " + precompiledJspWebXml);
}
for (ServletDef def : webXml.getServlets().values()) {
log.info("Registering precompiled JSP: {} = {} -> {}", def.getServletName(), def.getServletClass());
ServletRegistration.Dynamic reg = servletContext.addServlet(def.getServletName(), def.getServletClass());
reg.setLoadOnStartup(99);
}
for (Map.Entry<String, String> mapping : webXml.getServletMappings().entrySet()) {
log.info("Mapping servlet: {} -> {}", mapping.getValue(), mapping.getKey());
servletContext.getServletRegistration(mapping.getValue()).addMapping(mapping.getKey());
}
} catch (IOException e) {
throw new RuntimeException("Error registering precompiled JSPs", e);
}
};
}
示例Maven配置生成和编译JSP类,并生成precompiled-jsp-web.xml
:
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-catalina-ant</artifactId>
<version>8.0.32</version>
<scope>provided</scope>
</dependency>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.8</version>
<executions>
<execution>
<id>precompile-jsp-generate-java</id>
<phase>compile</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<echo message="Precompiling JSPs"/>
<property name="compile_classpath" refid="maven.compile.classpath"/>
<property name="target_dir" value="${project.basedir}/generated-sources/jspc" />
<path id="jspc_classpath">
<path path="${compile_classpath}"/>
</path>
<typedef resource="org/apache/catalina/ant/catalina.tasks" classpathref="jspc_classpath"/>
<mkdir dir="${target_dir}/java"/>
<mkdir dir="${target_dir}/resources"/>
<jasper
validateXml="false"
uriroot="${project.basedir}/src/main/webapp"
compilertargetvm="1.8"
compilersourcevm="1.8"
failonerror="true"
javaencoding="UTF-8"
webXml="${target_dir}/resources/precompiled-jsp-web.xml"
outputDir="${target_dir}/java/" >
</jasper>
<javac srcdir="${target_dir}/java" destdir="${project.build.outputDirectory}" classpathref="jspc_classpath" fork="true"/>
<copy todir="${project.build.outputDirectory}">
<fileset dir="${target_dir}/resources"/>
</copy>
</tasks>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<executions>
<execution>
<id>add-precompiled-jsp-java-sources</id>
<phase>generate-sources</phase>
<goals><goal>add-source</goal></goals>
<configuration>
<sources>
<source>${project.basedir}/generated-sources/jspc/java</source>
</sources>
</configuration>
</execution>
<execution>
<id>add-precompiled-jsp-resources</id>
<phase>generate-resources</phase>
<goals><goal>add-resource</goal></goals>
<configuration>
<resources>
<resource>
<directory>${project.basedir}/generated-sources/jspc/resources</directory>
</resource>
</resources>
</configuration>
</execution>
</executions>
</plugin>
web.xml
条目等效的ServletRegistrationBean
。手动完成这个过程的实际可行性取决于您有多少 JSP。 - Andy WilkinsonServletRegistration
bean配置。虽然这可能不切实际。或者,如果编译的“Servlet”带有@WebServlet
注解,您可以使用Boot的@ServletComponentScan
自动发现它们。 - Andy Wilkinson