1. SpringMVC简单使用

1.1 引入SpringMVC依赖

pom.xml

 

<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>4.0.0modelVersion>

  <groupId>org.examplegroupId>
  <artifactId>maven_testartifactId>
  <version>1.0-SNAPSHOTversion>
  <packaging>warpackaging>

  <name>maven_test Maven Webappname>
  
  <url>http://www.example.comurl>

  <properties>
    <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
    <maven.compiler.source>1.7maven.compiler.source>
    <maven.compiler.target>1.7maven.compiler.target>
    <spring.version>4.2.6.RELEASEspring.version>
  properties>

  <dependencies>
  
    <dependency>
      <groupId>junitgroupId>
      <artifactId>junitartifactId>
      <version>4.11version>
      <scope>testscope>
    dependency>
    
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-contextartifactId>
      <version>5.2.5.RELEASEversion>
    dependency>

    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-webmvcartifactId>
      <version>${spring.version}version>
    dependency>
    <dependency>
      <groupId>javax.servletgroupId>
      <artifactId>javax.servlet-apiartifactId>
      <version>4.0.1version>
      
      <scope>providedscope>
    dependency>
    <dependency>
      <groupId>javax.servlet.jspgroupId>
      <artifactId>javax.servlet.jsp-apiartifactId>
      <version>2.3.3version>
      
      <scope>providedscope>
    dependency>
    <dependency>
      <groupId>javax.servletgroupId>
      <artifactId>jstlartifactId>
      <version>1.2version>
    dependency>

  dependencies>


  <build>
    <finalName>maven_testfinalName>
    <pluginManagement>
      <plugins>
        <plugin>
          <artifactId>maven-clean-pluginartifactId>
          <version>3.1.0version>
        plugin>
        
        <plugin>
          <artifactId>maven-resources-pluginartifactId>
          <version>3.0.2version>
        plugin>
        <plugin>
          <artifactId>maven-compiler-pluginartifactId>
          <version>3.8.0version>
        plugin>
        <plugin>
          <artifactId>maven-surefire-pluginartifactId>
          <version>2.22.1version>
        plugin>
        <plugin>
          <artifactId>maven-war-pluginartifactId>
          <version>3.2.2version>
        plugin>
        <plugin>
          <artifactId>maven-install-pluginartifactId>
          <version>2.5.2version>
        plugin>
        <plugin>
          <artifactId>maven-deploy-pluginartifactId>
          <version>2.8.2version>
        plugin>
      plugins>
    pluginManagement>
  build>
project>

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在上面的依赖中，需要对servlet-api和jsp-api加上scope，因为tomcat的依赖包含这两个，如果不加，运行时会报错。这个scope 只能作用在编译和测试时，同时没有传递性。

1.2 创建mvc-dispatcher-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
       
    <context:component-scan base-package="com.crystallake.demo"/>
	
    <mvc:default-servlet-handler/>
    
    <mvc:annotation-driven/>
    <bean id="jspViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/>
    bean>
beans>
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InternalResourceViewResolver会将视图名解析为JSP文 件。另外，如果在你的JSP页面中使用了JSP标准标签库 （JavaServer Pages Standard Tag Library，JSTL）的 话，InternalResourceViewResolver能够将视图名解析为 JstlView形式的JSP文件，从而将JSTL本地化和资源bundle变量暴 露给JSTL的格式化（formatting）和信息（message）标签。

• prefix：前缀，请求的接口带上/WEB-INF/pages/前缀
• suffix：后缀，请求的接口后面带上.jsp
  这两个参数来自于InternalResourceViewResolver的父类UrlBasedViewResolver，如图所示：
  

1.3 配置web.xml

DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<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_3_1.xsd"
        version="3.1">
  <display-name>Archetype Created Web Applicationdisplay-name>

  <servlet>
    
    <servlet-name>mvc-dispatcherservlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
    <init-param>
      <param-name>contextConfigLocationparam-name>
      <param-value>classpath:mvc-dispatcher-servlet.xmlparam-value>
    init-param>
    <load-on-startup>1load-on-startup>
  servlet>

  <servlet-mapping>
    
    <servlet-name>mvc-dispatcherservlet-name>
    <url-pattern>/url-pattern>
  servlet-mapping>

web-app>

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• 如果不写任何参数配置(也就是没有servlet和servlet-mapping配置)，默认的是在/WEB-INF/applicationContext.xml。
• 如果指定了要加载的文件（就是配置了init-param），则会去加载相应的xml，而不会去加载/WEB-INF/下的applicationContext.xml。如果没有指定的话，默认会去/WEB-INF/下加载applicationContext.xml。
• 如果想要自定义文件名，需要在web.xml中加入contextConfigLocation这个context参数并指定classpath，这里默认加载resources文件夹下的xml文件
  

1.4 MainController创建

package com.crystallake.demo;


import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class MainController {

    @RequestMapping(value = "/",method = RequestMethod.GET)
    public String test(){
        return "main";
    }
}
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注意，webapp下的index.jsp要删除，不然它默认加载该jsp页面。

maven->clean->package->run


http://localhost:8083/maven_test_war_exploded/是baseUrl，因为在mvc-dispatcher-servlet.xml里面配置了前缀和后缀，所以它默认会加上前缀/WEB-INF/pages/，然后调用MainController的test方法返回main，然后自动加上后缀.jsp，所以最终的请求为
http://localhost:8083/maven_test_war_exploded/WEB-INF/pages/main.jsp