spring mvc源码学习笔记之二

pom.xml 内容如下

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.qs.demo</groupId><artifactId>test-010</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>4.3.30.RELEASE</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency></dependencies></project>

src/main/webapp/WEB-INF/web.xml 内容如下

<?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"><servlet><servlet-name>app</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextClass</param-name><param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value></init-param><init-param><param-name>contextInitializerClasses</param-name><!-- 值可以用逗号、分号、换行分割 --><param-value>com.qs.demo.A_ApplicationContextInitializer</param-value></init-param><!-- 小小优化，加快首次访问速度 --><load-on-startup>0</load-on-startup></servlet><servlet-mapping><servlet-name>app</servlet-name><!-- / 表示除了 xxx.jsp 之外的所有请求 --><!-- /* 表示所有请求 --><url-pattern>/</url-pattern></servlet-mapping>
</web-app>

com.qs.demo.A_ApplicationContextInitializer 内容如下

package com.qs.demo;import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;/*** @author qs* @date 2024/09/24*/
public class A_ApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {@Overridepublic void initialize(ConfigurableApplicationContext applicationContext) {System.out.println(this.getClass().getName() + " 参考 ContextLoader ");((AnnotationConfigWebApplicationContext) applicationContext).register(Conf.class);}
}

com.qs.demo.Conf 内容如下

package com.qs.demo;import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;/*** @author qs* @date 2025/01/03*/
@Configuration
@ComponentScan(basePackages = {"com.qs.demo"})
public class Conf {}

com.qs.demo.FirstController 内容如下

package com.qs.demo;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;/*** @author qs* @date 2024/12/20*/
@Controller
public class FirstController {@RequestMapping("/t01")@ResponseBodypublic void t01() {System.out.println("---------> " + System.currentTimeMillis());}@RequestMapping("/t02")@ResponseBodypublic String t02() {return "---------> " + System.currentTimeMillis();}}

以上就是全部代码

写这个例子主要是看名为 contextClass 的 servlet init-param 的用法。
在上面的例子中，我们用 contextClass 指定了使用 AnnotationConfigWebApplicationContext。
同时还使用 contextInitializerClasses 指定了用 com.qs.demo.A_ApplicationContextInitializer 来在应用上下文刷新之前对其进行自定义配置。