Spring 源碼分析(四) ——MVC(三)源碼入口

測試代碼

        框架配置

        如今就從 SpringMVC 的網站開發開始。固然,最早是用 Mavan 下載所需的 jar。下面是 pom.xml 配置:html

<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/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <groupId>com.kay</groupId>
  <artifactId>SpringMVCDome</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  
  <name>SpringMVCDome Maven Webapp</name>
  <url>http://maven.apache.org</url>

  <dependencies>
    <!-- Compile dependencies -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.1</version>
      <scope>provided</scope>
    </dependency>
    
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>4.2.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>4.2.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>4.2.5.RELEASE</version>
    </dependency>

    <!-- test dependencies -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>4.2.5.RELEASE</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>SpringMVCDome</finalName>
  </build>

</project>

        下面是代碼結構
java

        注:開發環境:web

                編碼:UTF-8
spring

                工具:IDEA 15.0.3apache

                JDK:JDK 1.八、Java EE 5
api

                開發環境:Maven 3瀏覽器

                Web 容器:Tomcat 9spring-mvc


               開發技術選型:mvc

                MVC 框架:Spring MVC 4.2.5
app

                表現層:JSP 


        web.xml配置

         打開src\main\webapp\WEB-INF\下的 web.xml 文件,對 web.xml 進行配置,以下:

<?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_3_1.xsd"
                              version="3.1">

  <display-name>SpringMVCDemo Web Application</display-name>

  <!-- 設置一個 servlet -->
  <servlet>
    <servlet-name>mvc-dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>mvc-dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!-- 配置一個 encodingFilter ,以免 post 請求中文出現亂碼 -->
  <filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
      <param-name>forceEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

</web-app>

        

        編寫 Model 代碼

         在model包中新建javabean類 IndexController(名稱並不固定,可任意取),並修改以下:

package org.spring.model;

/**
 * JavaBean UserBean 模板
 *
 * @Author kay
 * @version 1.0
 */
public class UserBean {

    private String name;
    
    private int age;

    public void setName(String name){
        this.name = name;
    }

    public String getName() {
        return this.name;
    }

    public void setAge(int age){
        this.age = age;
    }

    public int getAge() {
        return this.age;
    }
}


        編寫 Controller 代碼

        在controller包中新建java類 IndexController(名稱並不固定,可任意取),並修改以下:

package org.spring.controller;

import org.spring.model.UserBean;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import java.util.ArrayList;
import java.util.List;

/**
 * index 頁面的控制器,用於處理網站默認頁面的請求
 *
 * @Author kay
 * @version 1.0
 */
@Controller
public class IndexController {

    @RequestMapping(value = "/",method = RequestMethod.GET)
    public String defaultIndex(ModelMap modelMap){
        List<UserBean> userBeans = new ArrayList<UserBean>();
        UserBean userBeanA = new UserBean();
        UserBean userBeanB = new UserBean();

        userBeanA.setName("zhang");
        userBeanA.setAge(27);
        userBeanB.setName("li");
        userBeanB.setAge(35);

        userBeans.add(userBeanA);
        userBeans.add(userBeanB);
        modelMap.addAttribute("users", userBeans);

        return "index";
    }
}

        

        xxx-servlet.xml配置

        新建該xml文件後,在配置完web.xml後,需在web.xml同級目錄下新建 mvc-dispatcher-servlet.xml(-servlet前面是在servlet裏面定義的servlet名),以下:

<?xml version="1.0" encoding="UTF-8"?>
<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">

    <!-- 指明 controller 所在包,並掃描其中的註解 -->
    <context:component-scan base-package="org.spring.controller"/>

    <!-- 靜態資源(js、image等)的訪問 -->
    <mvc:default-servlet-handler/>

    <!-- 開啓註解 -->
    <mvc:annotation-driven/>

    <!-- ViewResolver 視圖解析器 -->
    <!-- 用於支持Servlet、JSP視圖解析 -->
    <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>

        

        index 頁面

        咱們刪除 webapp 目錄下的 index.jsp 文件,在WEB-INF目錄下新建文件夾pages,再在pages目錄下新建 index.jsp,並修改成以下所示:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="zh-CN">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">

        <title>SpringMVC Demo Home</title>
    </head>

    <body>
        <h3>This is SpringMVC Demo Home</h3>
        <c:forEach items="${users}" var="user">
            <c:out value="${user.name}"/><br/>
            <c:out value="${user.age}"/><br/>
        </c:forEach>
    </body>
</html>


        測試運行

        這樣,說明配置完成。這裏總結一下其相關機制:首先,瀏覽器訪問 localhost:8080,後臺controller攔截該請求,進行相應的處理(此處無),在跳轉到視圖 index.jsp進行顯示。此後,將會進行詳細的介紹。


源碼入口

        對於 Spring MVC 功能實現的分析,咱們首先從 web.xml 開始,在 web.xml 文件中咱們配置的是從 DispatcherServlet 開始的。

  <servlet>
    <servlet-name>mvc-dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>mvc-dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

        接下來,咱們的分析就從 DispatcherServlet 開始。



——水門(2016年3月寫於武漢)

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