SpringMVC工作原理（含案例图解）

SpimgMVC工作原理

第1步：浏览器发送指定的请求都会交给DispatcherServlet,他会委托其他模块进行真正的业务和数据处理
第2步：DispatcherServlet会查找到HandleMapping,根据浏览器的请求找到对应的Controller，并将请求交给目标Controller
第3步：目标Controller处理完业务后，返回一个ModelAndView给DispatcherServlet
第4步：DispatcherServlet通过ViewResolver视图解析器找到对应的视图对象View
第5步：视图对象View负责渲染，并返回到浏览器

案例分析

下面通过案例图解的方式理解下上面的工作原理

第1步-浏览器请求

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第2、3步-找到对应Controller

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第4、5步-解析视图对象，返回浏览器

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浏览器结果

源码

web.xml

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    <display-name>springmvcdisplay-name>
    <welcome-file-list>
        <welcome-file>index.htmlwelcome-file>
        <welcome-file>index.htmwelcome-file>
        <welcome-file>index.jspwelcome-file>
        <welcome-file>default.htmlwelcome-file>
        <welcome-file>default.htmwelcome-file>
        <welcome-file>default.jspwelcome-file>
    welcome-file-list>
    
    <servlet>
        <servlet-name>springmvcservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        
        <load-on-startup>1load-on-startup>
    servlet>

    
    <servlet-mapping>
        <servlet-name>springmvcservlet-name>
        <url-pattern>*.dourl-pattern>
    servlet-mapping>

web-app>

---

springmvc-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    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/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

        
        <mvc:annotation-driven>mvc:annotation-driven>

        
        <context:component-scan base-package="cn.itcast.controller">context:component-scan>

        
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/jsp/">property>
            <property name="suffix" value=".jsp">property>
        bean>
beans>

---

UserControll类

@Controller
@RequestMapping("user")
public class UserController {
    @RequestMapping("findAllUsers")
    public ModelAndView findAllUsers() {
        ModelAndView mv = new ModelAndView();
        ArrayList users = new ArrayList();
        for (int i = 0; i < 5; i++) {
            User user = new User();
            user.setUsername("zs" + i);
            user.setAge(20 + i);
            user.setIncome(16000.0+i*100);
            user.setIsMarry(false);
            user.setHobby(new String[] { "篮球"+i, "足球"+i });
            users.add(user);
        }
        mv.addObject("users", users);
        mv.setViewName("users");
        return mv;
    }
}

---

实体类

public class User implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private String username;
    private Integer age;
    private Boolean isMarry;
    private Double income;
    private String[] hobby;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

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

    public Boolean getIsMarry() {
        return isMarry;
    }

    public void setIsMarry(Boolean isMarry) {
        this.isMarry = isMarry;
    }

    public Double getIncome() {
        return income;
    }

    public void setIncome(Double income) {
        this.income = income;
    }

    public String[] getHobby() {
        return hobby;
    }

    public void setHobby(String[] hobby) {
        this.hobby = hobby;
    }

    @Override
    public String toString() {
        return "User [username=" + username + ", age=" + age + ", isMarry=" + isMarry + ", income=" + income
                + ", hobby=" + Arrays.toString(hobby) + "]";
    }

}

---

JSP页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title heretitle>
<link rel="stylesheet" type="text/css" href="/css/user.css" />
head>
<body>
    <table id="customers">
        <tr>
            <th>用户名th>
            <th>年龄th>
            <th>收入th>
            <th>婚姻状态th>
            <th>兴趣爱好th>
        tr>
        
        <c:forEach items="${users}" var="user">
            <tr>
                <td>${user.username}td>
                <td>${user.age}td>
                <td>${user.income}td>
                
                <td><c:choose>
                        <c:when test="${user.isMarry}">已婚c:when>
                        <c:otherwise>未婚c:otherwise>
                    c:choose>
                td>

                <td>
                
                <c:forEach items="${user.hobby}" var="hobby" varStatus="status">
                    ${hobby} 
                    
                    <c:if test="${!status.last}">,c:if>
                c:forEach>
                td>
            tr>
        c:forEach>
    table>
body>
html>