注解驱动的spring mvc(一)

基于注解驱动的配置越来越流行，使用注解加上Conversion over Configuration可以大为简化配置的过程。struts 2.1.6引入的Conversion插件在注解和规约驱动的配置上做的很好。spring在2.5以后也对MVC进行了大幅度改进，现在你无须让 Controller 继承任何接口，无需在 XML 配置文件中定义请求和 Controller 的映射关系，仅仅使用注解就可以让一个 POJO 具有 Controller 的绝大部分功能。

一：Hello World

1.编写Controller

package mao.shijie.springmvc.controller;

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

@Controller
@RequestMapping("/welcome.htm") //这个注解相当于实现Controller接口
public class WelcomeController {

    @RequestMapping
    public void welcome() {
    }

}

package mao.shijie.springmvc.controller;

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

@Controller
@RequestMapping("/welcome.htm") //这个注解相当于实现Controller接口
public class WelcomeController {

	@RequestMapping
	public void welcome() {		
	}

}

注意该类只是一个加上了annotation的pojo。

 

2.加入必须的jar，spring mvc没有引入过多的标签库，一般使用jstl标签库就可以完成绝大数工作。

2.配置web.xml

      <!-- spring配置文件加载路径   -->
      <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>spring</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>spring</servlet-name>
    <url-pattern>*.htm</url-pattern>
</servlet-mapping>

       <!-- spring配置文件加载路径   -->
       <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>spring</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>spring</servlet-name>
		<url-pattern>*.htm</url-pattern>
	</servlet-mapping>

spring mvc还需要一个xxx-servlet.xml的配置文件，xxx为web.xml中servlet-name，该例中为/WEB-INF/spring-servlet.xml

 

3.配置spring-servlet.xml

<?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:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-2.5.xsd">

    <!-- 把标记了@Controller注解的类转换为bean -->
    <context:component-scan base-package="mao.shijie.springmvc.controller" />

    <!-- 启动Spring MVC的注解功能，完成请求和注解POJO的映射 -->
    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />

    <!-- 对模型视图名称的解析，即在模型视图名称添加前后缀 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
        p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />

    <!-- 处理Mutipart文件上次的bean -->
    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
        p:defaultEncoding="utf-8" />

</beans>

<?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:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
       http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
       http://www.springframework.org/schema/context 
       http://www.springframework.org/schema/context/spring-context-2.5.xsd">
    
	<!-- 把标记了@Controller注解的类转换为bean -->
	<context:component-scan base-package="mao.shijie.springmvc.controller" />

	<!-- 启动Spring MVC的注解功能，完成请求和注解POJO的映射 -->
	<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />

	<!-- 对模型视图名称的解析，即在模型视图名称添加前后缀 -->
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
		p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />
	
	<!-- 处理Mutipart文件上次的bean -->
	<bean id="multipartResolver"
		class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
		p:defaultEncoding="utf-8" />
		
</beans>

 

4.编写视图，在前面的配置中，制定了一个InternalResourceViewResolver，该bean更具视图名加上前缀/WEB-INF/jsp/和后缀.jsp找到视图，视图名的确定后面会讲到，该例中视图名更具Url确定，为welcome，所以视图文件为/WEB-INF/jsp/welcome.jsp。

<%@ page language="java" contentType="text/html; charset=utf-8"
    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=ISO-8859-1">
        <title>Insert title here</title>
    </head>
    <body>
        <h1>Hello World!</h1>
    </body>
</html>

<%@ page language="java" contentType="text/html; charset=utf-8"
	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=ISO-8859-1">
		<title>Insert title here</title>
	</head>
	<body>
		<h1>Hello World!</h1>
	</body>
</html>

 启动服务器，访问http://localhost:8080/spring-mvc/welcome.htm

二：一个Controller处理多个Url

@Controller
public class UserController {
    @RequestMapping("/user/regist.htm")
    public void regist(){

    }
    @RequestMapping("/user/login.htm")
    public void login(){

    }
}

@Controller
public class UserController {
	@RequestMapping("/user/regist.htm")
	public void regist(){
		
	}
	@RequestMapping("/user/login.htm")
	public void login(){
		
	}
}

通过在public方法上添加@RequestMapping指定Url参数。根据Url得到视图，该例中视图为/WEB-INF/jsp/user/regist，/WEB-INF/jsp/user/login。

 

在使用一个Controller处理多个Url时，可以通过一个Url地址，不同的请求参数来区别两个方法。例如

 

@RequestMapping(params="type=user",value="/user/list.htm")
public void listAllUser(){

}

@RequestMapping(params="type=admin",value="/user/list.htm")
public void listAllAdmin(){

}

@RequestMapping(params="type=user",value="/user/list.htm")
public void listAllUser(){
		
}

@RequestMapping(params="type=admin",value="/user/list.htm")
public void listAllAdmin(){
		
}

 同样还可以通过HTTP Method来区别两个方法

@RequestMapping(value = "/user/regist.htm", method = RequestMethod.GET)
public void regist() {

}

@RequestMapping(value = "/user/regist.htm", method = RequestMethod.POST)
public void registPost() {

}

@RequestMapping(value = "/user/regist.htm", method = RequestMethod.GET)
public void regist() {

}

@RequestMapping(value = "/user/regist.htm", method = RequestMethod.POST)
public void registPost() {

}

 method属性可以让Controller处理特定的HTTP方法，本例中为POST和GET，也可以指定同时处理多个HTTP方法。

三：请求参数的传入

在Controller方法中声明方法参数，那么同名的HTTP请求参数将自动转换为相应类型，并传入方法。

@RequestMapping("/user/regist.htm")
public void regist(String username, String password, int age) {

}

@RequestMapping("/user/regist.htm")
public void regist(String username, String password, int age) {
		
}

 当访问地址/user/regist.html?age=20&username=user&password=pwd时，那么传入regist方法的username==user，password==pwd，age==20。

 

请求参数的传入同样支持类似与struts2 ModelDriven的bean参数传递。例如把该例中的username，password，age参数通过user bean传入。

public class User {
    private String username;
    private String password;
    private int age;

    //getter,setter

}

public class User {
	private String username;
	private String password;
	private int age;
	
	//getter,setter
	
}

@RequestMapping("/user/regist.htm")
public void regist(User user) {
    System.out.println(user.getAge());
    System.out.println(user.getUsername());
}

@RequestMapping("/user/regist.htm")
public void regist(User user) {
	System.out.println(user.getAge());
	System.out.println(user.getUsername());
}

访问http://localhost:8080/spring-mvc/user/regist.htm?username=user&password=pwd&age=20时，将打印出20，pwd。spring为自动查找bean的属性，并更具属性名映射相应的请求参数。