使用Spring MVC构建Hello World

使用Spring MVC构建Hello World

本文演示如何使用Spring MVC做出最简单的Hello World应用。

示例1

项目创建和之前一样，不过在最后一步要选择Spring Web MVC：

项目结构如下：

web.xml源码：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" 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">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>2</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>

    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>redirect.jsp</welcome-file>
    </welcome-file-list>
</web-app>

如果遇到匹配*.htm的URL，会使用org.springframework.web.servlet.DispatcherServlet来处理。

applicationContext.xml源码：

<?xml version='1.0' encoding='UTF-8' ?>
<!-- was: <?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:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

    <!--bean id="propertyConfigurer"
          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
          p:location="/WEB-INF/jdbc.properties" />

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource"
    p:driverClassName="${jdbc.driverClassName}"
    p:url="${jdbc.url}"
    p:username="${jdbc.username}"
    p:password="${jdbc.password}" /-->

    <!-- ADD PERSISTENCE SUPPORT HERE (jpa, hibernate, etc) -->

</beans>

applicationContext.xml是Spring的配置文件。

dispatcher-servlet.xml源码：

<?xml version='1.0' encoding='UTF-8' ?>
<!-- was: <?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:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

    <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/>

    <!--
    Most controllers will use the ControllerClassNameHandlerMapping above, but
    for the index controller we are using ParameterizableViewController, so we must
    define an explicit mapping for it.
    -->
    <bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <property name="mappings">
            <props>
                <prop key="index.htm">indexController</prop>
            </props>
        </property>
    </bean>

    <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          p:prefix="/WEB-INF/jsp/"
          p:suffix=".jsp" />

    <!--
    The index controller.
    -->
    <bean name="indexController"
          class="org.springframework.web.servlet.mvc.ParameterizableViewController"
          p:viewName="index" />

</beans>

在<bean id="viewResolver" .../>定义了JSP模板文件的位置和后缀（这样其他地方就可以省略后缀了）。

URL为index.htm时，对应的控制器是indexController，其调用了/WEB-INF/jsp/下的模板index.jsp。

redirect.jsp源码

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<% response.sendRedirect("index.htm"); %>

index.jsp源码

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Welcome to Spring Web MVC project</title>
    </head>

    <body>
        <p>Hello! This is the default welcome page for a Spring Web MVC project.</p>
        <p><i>To display a different welcome page for this project, modify</i>
            <tt>index.jsp</tt> <i>, or create your own welcome page then change
                the redirection in</i> <tt>redirect.jsp</tt> <i>to point to the new
                welcome page and also update the welcome-file setting in</i>
            <tt>web.xml</tt>.</p>
    </body>
</html>

运行项目，打开浏览器访问http://localhost:8084/Project_0102/，会自动跳转到 http://localhost:8084/Project_0102/index.htm，并显示index.jsp的内容。

Hello World

修改dispatcher-servlet.xml，将<bean id="urlMapping" .../>修改为：

<bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="mappings">
        <props>
            <prop key="index.htm">indexController</prop>
            <prop key="hello.htm">helloController</prop>
        </props>
    </property>
</bean>

并添加：

<bean name="helloController"
      class="me.letiantian.controller.HelloController" />

HelloController.java的源码如下：

package me.letiantian.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public class HelloController implements  Controller{

    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {

        ModelAndView mv = new ModelAndView();
        mv.addObject("message", "Hello World!你好");  
        mv.setViewName("hello");
        return mv;
    }

}

模板hello.jsp的源码如下：

<html>
    <head>
        <title>Hello world</title>
    </head>
    <body>
        <h1>${message}</h1>
    </body>
</html>

创建static目录，在static目录下创建test.js，内容如下：

console.log("hello world");

在web.xml中添加：

<servlet-mapping>  
    <servlet-name>default</servlet-name>
    <url-pattern>*.jpg</url-pattern>   
</servlet-mapping>  

<servlet-mapping>  
    <servlet-name>default</servlet-name>
    <url-pattern>*.png</url-pattern>   
</servlet-mapping>  

<servlet-mapping>    
    <servlet-name>default</servlet-name>  
    <url-pattern>*.js</url-pattern>  
</servlet-mapping>  

<servlet-mapping>    
    <servlet-name>default</servlet-name>    
    <url-pattern>*.css</url-pattern>   
</servlet-mapping>

好了，现在的项目结构如下：

浏览器访问结果：

乱码了~囧~

解决方法：
在HelloController.java加入response.setContentType("text/html;charset=UTF-8");：

package me.letiantian.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public class HelloController implements  Controller{

    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        response.setContentType("text/html;charset=UTF-8");  // 新加入的内容
        ModelAndView mv = new ModelAndView();
        mv.addObject("message", "Hello World!你好");  
        mv.setViewName("hello");
        return mv;
    }

}

示例2

换种方法配置静态资源

删掉在web.xml中的：

<servlet-mapping>  
    <servlet-name>default</servlet-name>
    <url-pattern>*.jpg</url-pattern>   
</servlet-mapping>  

<servlet-mapping>  
    <servlet-name>default</servlet-name>
    <url-pattern>*.png</url-pattern>   
</servlet-mapping>  

<servlet-mapping>    
    <servlet-name>default</servlet-name>  
    <url-pattern>*.js</url-pattern>  
</servlet-mapping>  

<servlet-mapping>    
    <servlet-name>default</servlet-name>    
    <url-pattern>*.css</url-pattern>   
</servlet-mapping>

在dispatcher-servlet.xml中增加以下内容：

<?xml version='1.0' encoding='UTF-8' ?>
<!-- was: <?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:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       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-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">

    <!-- 其他内容 -->
    <mvc:resources mapping="/static/**" location="/static/"/>  

</beans>

注意，在beans的属性中增加了xmlns:mvc="http://www.springframework.org/schema/mvc"，属性xsi:schemaLocation中增加了http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd。

不再使用任何后缀（例如.html，.jsp）

将redirect.jsp修改为：

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<% response.sendRedirect("index"); %>

将web.xml中的：

<servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>*.htm</url-pattern>
</servlet-mapping>

修改为：

<servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

将dispatcher-servlet.xml中的：

<bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="mappings">
        <props>
            <prop key="index.htm">indexController</prop>
            <prop key="hello.htm">helloController</prop>
        </props>
    </property>
</bean>

修改为：

<bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="mappings">
        <props>
            <prop key="index">indexController</prop>
            <prop key="hello">helloController</prop>
        </props>
    </property>
</bean>

然后，浏览器访问http://localhost:8084/Project_0102/hello。

示例3

这个示例展示如何获取URL中的数据。

修改HelloController.java:

package me.letiantian.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public class HelloController implements  Controller{

    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        response.setContentType("text/html;charset=UTF-8");
        ModelAndView mv = new ModelAndView();
        mv.addObject("name", request.getParameter("name"));  
        mv.setViewName("hello");
        return mv;
    }

}

修改hello.jsp：

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<html>
    <head>
        <title>Hello world</title>
    </head>
    <body>
        <h1>${pageContext.request.contextPath}</h1>

        <form action="${pageContext.request.contextPath}/hello" method="GET">
            <input name="name" />
            <input type="submit" value="提交"/>
        </form>

        <h2>提交的数据： ${name}</h2>

    </body>
</html>

${pageContext.request.contextPath}的输出是/Project_0102。
浏览器访问：

再编辑JSP文件时候遇到了这样的问题：

The header.jspf contains characters which will probably be damaged during conversion to the ISO-8859-1 character set. Do you want to save the file using this character set?

解决办法见http://stackoverflow.com/questions/15499182/netbeans-forces-me-to-save-in-specific-encoding。

资料

• Chapter 13. Web MVC framework

• Spring MVC – How to include JS or CSS files in a JSP page

• dispatcher-servlet.xml and application-context.xml的区别

• Spring MVC SimpleUrlHandlerMapping example
• springMVC中文乱码问题

• SpringMVC 基于注解的Controller @RequestMapping @RequestParam..

• urlMapping也可以通过注解来定义，例如Spring 4 MVC Hello World Tutorial – Full Example。