我正在使用Spring启动，之前我们使用Spring和Tomcat。 两年前我们使用Spring和Tomcat时，我们使用maven插件来预编译jsp。 在部署之后避免每次首次访问都要进行编译是非常有用的。
但是，我们知道的所有maven插件都会转储一个web.xml文件，该文件列出了所有jsp和相关的生成的servlet。 使用Spring启动时，它不再使用web.xml，因此忽略此文件。
我们仍然有编辑，这是一个安全带，但每页首次访问都会受到惩罚。
有人知道是否可以在Spring启动应用程序中预编译jsp？
答案 0 :(得分：16)
我在服务器启动时（不必使用JspC，更简单的构建文件）和构建时（服务器启动时间更快）进行预编译。我动态注册生成的servlet，因此如果添加/删除JSP，则不必手动更改任何文件。
使用ServletRegistration.Dynamic为每个JSP注册JSP_SERVLET_CLASS Servlet。
使用initParameter jspFile设置JSP文件名（ref）
e.g。适用于ServletContextInitializer（ref）中的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);
}
使用web.xml（JspC）为每个JSP和ref及其servlet映射生成Java源文件。
然后使用ServletContext注册这些内容（通过Tomcat＆＃39; WebXmlParser解析web.xml，例如SpringBoot：
@Value("classpath:precompiled-jsp-web.xml")
private Resource precompiledJspWebXml;
@Bean
public ServletContextInitializer registerPreCompiledJsps() {
return servletContext -> {
// Use Tomcat's web.xml parser (assume complete XML file and validate).
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);
}
};
}
Maven配置示例，用于生成和编译JSP类，并生成precompiled-jsp-web.xml：
<!-- Needed to get the jasper Ant task to work (putting it in the plugin's dependencies didn't work) -->
<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>
<!-- Can't be generate-sources because we need the compiled Henry taglib classes already! -->
<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="${target_dir}/java/" >
</jasper>
<!-- Can't use Maven to compile the JSP classes because it has already compiled the app's classes
(needed to do that becuase JspC needs compiled app classes) -->
<javac srcdir="${target_dir}/java" destdir="${project.build.outputDirectory}" classpathref="jspc_classpath" fork="true"/>
<!-- Have to copy the web.xml because process-resources phase has already finished (before compile) -->
<copy todir="${project.build.outputDirectory}">
<fileset dir="${target_dir}/resources"/>
</copy>
</tasks>
</configuration>
</execution>
</executions>
</plugin>
<!-- Not strictly necessary, because Ant does the compilation, but at least attempts to keep it in sync with Maven -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<executions>
<execution>
<id>add-precompiled-jsp-java-sources</id>
<phase>generate-sources</phase>
<goals><goal>add-source</goal></goals>
<configuration>
<sources>
<source>${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>${project.basedir}/generated-sources/jspc/resources</directory>
</resource>
</resources>
</configuration>
</execution>
</executions>
</plugin>
答案 1 :(得分：1)
上面概述的“在服务器启动时”的注释：如果应用程序打包在可执行jar中，您创建的servlet将默认处于开发模式，因此如果您在生产模式下使用它，您还应该设置development = false ++以防止再次编译jsps：
reg.setInitParameter("genStringAsCharArray", "true");
reg.setInitParameter("trimSpaces", "true");
reg.setInitParameter("development", "false");
答案 2 :(得分：0)
基于paulcm的出色回答，我想出了自己的解决方案，因为上述解决方案对我不起作用，并且我无法找到错误。也许上面的答案对于tomcat9已经过时了。否则它在多模块设置中存在一些问题。但是：所有积分都属于paulcm
这只是编译时的解决方案。
将这两个插件添加到您的pom.xml
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-jspc-maven-plugin</artifactId>
<version>9.4.15.v20190215</version>
<executions>
<execution>
<id>jspc</id>
<goals>
<goal>jspc</goal>
</goals>
<configuration>
<mergeFragment>true</mergeFragment>
<sourceVersion>1.8</sourceVersion>
<targetVersion>1.8</targetVersion>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<configuration>
<webXml>${project.basedir}/target/web.xml</webXml>
</configuration>
</plugin>
添加一个空的web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0"
metadata-complete="true">
<session-config>
<cookie-config>
</cookie-config>
</session-config>
</web-app>
添加注册表
import org.apache.tomcat.util.descriptor.web.ServletDef;
import org.apache.tomcat.util.descriptor.web.WebXml;
import org.apache.tomcat.util.descriptor.web.WebXmlParser;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.web.servlet.ServletContextInitializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.xml.sax.InputSource;
import javax.servlet.ServletRegistration;
import java.io.InputStream;
import java.util.Map;
@Configuration
public class PreCompileJspRegistry {
private Logger logger = LoggerFactory.getLogger(this.getClass());
@Bean
public ServletContextInitializer registerPreCompiledJsps() {
return servletContext -> {
InputStream inputStream = servletContext.getResourceAsStream("/WEB-INF/web.xml");
if (inputStream == null) {
logger.info("web.xml konnte nicht gelesen werden");
return;
}
try {
WebXmlParser parser = new WebXmlParser(false, false, true);
WebXml webXml = new WebXml();
boolean success = parser.parseWebXml(new InputSource(inputStream), webXml, false);
if (!success) {
logger.error("Error registering precompiled JSPs");
}
for (ServletDef def : webXml.getServlets().values()) {
logger.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()) {
logger.info("Mapping servlet: {} -> {}", mapping.getValue(), mapping.getKey());
servletContext.getServletRegistration(mapping.getValue()).addMapping(mapping.getKey());
}
} catch (Exception e) {
logger.error("Error registering precompiled JSPs", e);
}
};
}
}