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实例详解SpringMVC入门使用

程序员文章站 2022-06-23 13:35:07
mvc模式(model-view-controller)是软件工程中的一种软件架构模式,把软件系统分为三个基本部分:模型(model),视图(view)和控制器(controller).通过分层使开发...

mvc模式(model-view-controller)是软件工程中的一种软件架构模式,把软件系统分为三个基本部分:模型(model),视图(view)和控制器(controller).通过分层使开发的软件结构更清晰,从而达到开发效率的提高,可维护性和扩展性得到提高.spring提供的mvc框架是在j2ee web开发中对mvc模式的一个实现,本文通过实例讲解一下spring mvc 的使用.

先来看一个http request在spring的mvc框架是怎么被处理的:(图片来源于spring in action)

实例详解SpringMVC入门使用

1,dispatcherservlet是spring mvc的核心,它的本质是一个实现了j2ee标准中定义的httpservlet,通过在web.xml配置<servlet-mapping>,来实现对request的监听.

	<servlet>
		<servlet-name>springtestservlet</servlet-name>
		<servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
		<load-on-startup>2</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>springtestservlet</servlet-name>
		<url-pattern>*.do</url-pattern>
	</servlet-mapping>

** 以.do结尾的request都会由springtestservlet来处理.

2,3,当接受到request的时候,dispatcherservlet根据handlermapping的配置(handlermapping的配置文件默认根据<servlet-name>的值来决定,这里会读取springtestservlet-servlet.xml来获得handlermapping的配置信息),调用相应的controller来对request进行业务处理.

	<bean id="simpleurlmapping" class="org.springframework.web.servlet.handler.simpleurlhandlermapping">
		<property name="mappings">
			<props>
				<prop key="/login.do">logincontroller</prop>
			</props>
		</property>
	</bean>
	<bean id="logincontroller" class="com.test.spring.mvc.contoller.logincontroller">
		<property name="sessionform">
			<value>true</value>
		</property>
		<property name="commandname">
			<value>logincommand</value>
		</property>
		<property name="commandclass">
			<value>com.test.spring.mvc.commands.logincommand</value>
		</property>
		<property name="authenticationservice">
			<ref bean="authenticationservice"/>
		</property>
		<property name="formview">
			<value>login</value>
		</property>
		<property name="successview">
			<value>logindetail</value>
		</property>
	</bean>

** 以login.do结尾的request由logincontroller来处理.<property name="formview">配置的是controller接收到http get请求的时候需要显示的逻辑视图名,本例是显示login.jsp,<property name="successview">配置的是在接收到http post请求的时候需要显示的逻辑视图名,在本例中即login.jsp提交的时候需要显示名为logindetail的逻辑视图.

4,controller进行业务处理之后,返回一个modelandview对象.

return new modelandview(getsuccessview(),"logindetail",logindetail);

5,6,dispatcherservlet根据viewresolver的配置(本例是在springtestservlet-servlet.xml文件中配置)将逻辑view转换到真正要显示的view,如jsp等.

	<bean id="viewresolver" class="org.springframework.web.servlet.view.internalresourceviewresolver">
		<property name="viewclass">
			<value>org.springframework.web.servlet.view.jstlview</value>
		</property>
		<property name="prefix">
			<value>/jsp/</value>
		</property>
		<property name="suffix">
			<value>.jsp</value>
		</property>
	</bean>

**其作用是将controller中返回的modleandview解析到具体的资源(jsp文件),如上例中的return new modelandview(getsuccessview();按照上面viewresolver配置,会解析成/jsp/logindetail.jsp.规则为prefix+modelandview的第二个参数+suffix.

示例的完整代码如下:

1web.xml:

<?xml version="1.0" encoding="utf-8"?>
<web-app id="webapp_id" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" 
xsi:schemalocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	<display-name>
	prjspring3</display-name>
	<servlet>
		<servlet-name>springtestservlet</servlet-name>
		<servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
		<load-on-startup>2</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>springtestservlet</servlet-name>
		<url-pattern>*.do</url-pattern>
	</servlet-mapping>
	<listener>
		<listener-class>org.springframework.web.context.contextloaderlistener</listener-class>
	</listener>
	<listener>
		<listener-class>org.springframework.web.context.request.requestcontextlistener</listener-class>
	</listener>
	<context-param>
		<param-name>contextconfiglocation</param-name>
		<param-value>/web-inf/springtest-services.xml</param-value>
	</context-param>
	<jsp-config>
		<taglib>
			<taglib-uri>/spring</taglib-uri>
			<taglib-location>/web-inf/spring.tld</taglib-location>
		</taglib>
	</jsp-config>
</web-app>
2,springtestservlet-servlet.xml的内容如下:
<?xml version="1.0" encoding="utf-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" 
xsi:schemalocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
	<bean id="simpleurlmapping" class="org.springframework.web.servlet.handler.simpleurlhandlermapping">
		<property name="mappings">
			<props>
				<prop key="/login.do">logincontroller</prop>
			</props>
		</property>
	</bean>
	<bean id="logincontroller" class="com.test.spring.mvc.contoller.logincontroller">
		<property name="sessionform">
			<value>true</value>
		</property>
		<property name="commandname">
			<value>logincommand</value>
		</property>
		<property name="commandclass">
			<value>com.test.spring.mvc.commands.logincommand</value>
		</property>
		<property name="authenticationservice">
			<ref bean="authenticationservice"/>
		</property>
		<property name="formview">
			<value>login</value>
		</property>
		<property name="successview">
			<value>logindetail</value>
		</property>
	</bean>
	<bean id="viewresolver" class="org.springframework.web.servlet.view.internalresourceviewresolver">
		<property name="viewclass">
			<value>org.springframework.web.servlet.view.jstlview</value>
		</property>
		<property name="prefix">
			<value>/jsp/</value>
		</property>
		<property name="suffix">
			<value>.jsp</value>
		</property>
	</bean>
</beans>

3,springtest-services.xml的内容:

 <bean id="authenticationservice" class="com.test.spring.mvc.services.authenticationservice"/>

4,java代码:

public class logincontroller extends simpleformcontroller {
	org.springframework.web.servlet.dispatcherservlet t;
	protected modelandview onsubmit(object command) throws exception{		
		logincommand logincommand = (logincommand) command;
		authenticationservice.authenticate(logincommand);
		logindetail logindetail = authenticationservice.getlogindetail(logincommand.getuserid());
		return new modelandview(getsuccessview(),"logindetail",logindetail);
	}	
	private authenticationservice authenticationservice;
	public authenticationservice getauthenticationservice() {
		return authenticationservice;
	}
	public void setauthenticationservice(
			authenticationservice authenticationservice) {
		this.authenticationservice = authenticationservice;
	}
	....
public class logincommand {
	private string userid;
	private string password;
	....
public class logindetail {
	private string username;
public class authenticationservice {		
	public void authenticate(logincommand command) throws exception{
		if(command.getuserid()!= null && command.getuserid().equalsignorecase("test") 
				&& command.getpassword()!= null && command.getpassword().equalsignorecase("test")){	
		}else{
			throw new exception("user id is not authenticated"); 
		}
	}
	public logindetail getlogindetail(string userid){
		return new logindetail(userid);
	}
}	

5,jsp文件:放在web-inf的jsp文件夹内

login.jsp:
<html><head>
<title>login to spring test</title></head>
<body>
<h1>please enter your userid and password.</h1>
<form method="post" action="login.do">
<table width="95%" bgcolor="f8f8ff" border="0" cellspacing="0" cellpadding="5">
<tr>
<td alignment="right" width="20%">user id:</td>
<td width="20%"><input type="text" name="userid" value="test"></td>
<td width="60%">
</tr>
<tr>
<td alignment="right" width="20%">password:</td>
<td width="20%"><input type="password" name="password" value="test"></td>
<td width="60%">
</tr>
</table>
<br>
<input type="submit" alignment="center" value="login">
</form>
</body>
</html>
 
logindetail.jsp:
<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c"%> 
<html><head>
<title>login to spring test</title></head>
<body>
<h1>login details:</h1>
<br/>
login as: <c:out value ="${logindetail.username}"/>
<br/>
<a href="/s3/login.do" rel="external nofollow" >logout</a>
</body>
</html>

在浏览器的地址栏输入http://localhost:8080/xxx/login.do进入login.jsp页面.

对配置的一些扩充点:

1为handlermapping和controller的配置指定文件名称.

<servlet>  
    <servlet-name>springtestservlet</servlet-name>  
    <servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>  
    <init-param>  
        <param-name>contextconfiglocation</param-name>  
        <param-value>classpath*:/xxx.xml</param-value>  
    </init-param>  
    <load-on-startup>1</load-on-startup>  
</servlet>  

2,加入对mvc注解的支持:

<?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-3.0.xsd
	http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
	http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
	<context:annotation-config />
	<context:component-scan base-package="com.test.spring.mvc.contoller" />
	<mvc:annotation-driven />
 
@controller
public class annotationcontroller {
    @requestmapping("annotation.do")
    protected void test(httpservletrequest request,
            httpservletresponse response) throws exception{        
        response.getwriter().println("test spring mvc annotation");
    }

3,注解和simpleformcontroller同时使用需要在dispatcherservlet对应的servlet配置文件(本例是springtestservlet-servlet.xml)里面配置:

<bean class="org.springframework.web.servlet.mvc.simplecontrollerhandleradapter"/>
 
否则会发生下面的异常:
javax.servlet.servletexception: no adapter for handler [com.test.spring.mvc.contoller.logincontroller@6ac615]: does your handler implement a supported interface like controller?
	org.springframework.web.servlet.dispatcherservlet.gethandleradapter(dispatcherservlet.java:982)
	org.springframework.web.servlet.dispatcherservlet.dodispatch(dispatcherservlet.java:770)
	org.springframework.web.servlet.dispatcherservlet.doservice(dispatcherservlet.java:716)
	org.springframework.web.servlet.frameworkservlet.processrequest(frameworkservlet.java:647)
	org.springframework.web.servlet.frameworkservlet.doget(frameworkservlet.java:552)
	javax.servlet.http.httpservlet.service(httpservlet.java:621)
	javax.servlet.http.httpservlet.service(httpservlet.java:722)

在web应用中的context配置文件通过下面的方式load,contextloaderlistener是一个实现了servletcontextlistener的listener,
它能够访问<context-param>而得到配置文件的路径,加载后初始化了一个webapplicationcontext,并且将其作为attribute放在了servletcontext中,
所有可以访问servletcontext的地方则可以访问webapplicationcontext.

	<listener>
		<listener-class>org.springframework.web.context.contextloaderlistener</listener-class>
	</listener>
	<context-param>
		<param-name>contextconfiglocation</param-name>
		<param-value>
			/web-inf/springtest-services.xml,
			classpath:conf/jndidsappcontext.xml
		</param-value>
	</context-param>

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相关标签: SpringMVC