springMVC 系列 1-demo

创建一个maven项目

从模板页创建。模板选择org.apache.maven.archetypes:maven-archetype-webapp
创建完的项目，目录结构不全，需要在main下创建文件夹java、resources。然后在文件夹java上右击“Mark Directory as”选择"Sources Root"。在resources上右击“Mark Directory as”选择“Resources Root”

在web.xml里配置servlet

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--配置Servlet的初始化，读取springMVC的配置文件，创建spring容器-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value><!--将配置文件引入-->
    </init-param>
    <load-on-startup>1</load-on-startup><!--配置servlet启动时加载对象-->
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern><!--拦截所有请求-->
  </servlet-mapping>
</web-app>

在resources里添加springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <!-- 开启注解扫描 -->
    <context:component-scan base-package="com.mantishell"/>

    <!-- 视图解析器对象，这里的id可以随便写 -->
    <!--InternalResourceViewResolver是Spring MVC 内置的一个视图解析器，该解析器是遵循着一种约定：会在视图名上添加前缀和后缀，进而确定一个 Web 应用中视图资源的物理路径-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!-- 开启SpringMVC框架注解的支持 -->
    <mvc:annotation-driven/>
</beans>

坐标引入

<?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.mantishell</groupId>
  <artifactId>springMvc_01_start</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>springMvc_01_start Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <spring.version>5.0.2.RELEASE</spring.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.0</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <finalName>springMvc_01_start</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>入门程序</h3>

    <a href="hello">入门程序</a>
</body>
</html>

java文件夹下创建控制器com.mantishell.controller.HelloController

package com.mantishell.controller;

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

@Controller
public class HelloController {

    @RequestMapping(path="/hello")
    public String sayHello(){
        System.out.println("Hello StringMVC");
        return "success";//默认跳转到视图
    }
}

在WEB-INF文件夹下创建文件夹pages

然后创建 success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>入门了</h3>
</body>
</html>

配置部署

整个过程是怎么样的呢？

当气动Tomcat服务器的时候，因为配置了load-on-startup标签，所以会创建DispatcherServlet对象，并加载springMVC.xml配置文件。
开启的注解扫描，那么HelloController对象会被创建，由spring来管理
从index.jsp发送请求，请求会先到达DispatcherServlet核心控制器，根据配置@RequestMapping注解找到执行的具体方法
根据执行方法的返回值，再根据配置的视图解析器，去指定的目录下查找指定名称的JSP文件