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SpringMVC是什么
昆明IT培训的小编知道,MVC的全称是Model View Controller,通过实现MVC框架可以很好的数据、视图、业务逻辑进行分离。Spring MVC也是一种MVC框架,它是SpringFrameWork的后续产品,同样需要Spring的Jar包才能运行起来。
SpringMVC的设计原理
Spring MVC的设计是围绕着DispatcherServlet展开的,由DispatcherServlet将请求派发到特定的Controller。
SpringMVC入门示例
我的项目结构:
1,复制Jar包
将Spring的Jar包复制到lib目录下。
2,Web.xml文件
配置Web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="#/xml/ns/javaee" xsi:schemaLocation="#/xml/ns/javaee #/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<!--
this name matched project name
-->
<display-name>SpringMVC</display-name>
<!--
transmit to dispacherServlet to deal with information that passed from table servlet-mapping
-->
<servlet>
<servlet-name>mySpring</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>mySpring</servlet-name>
<url-pattern>*.ms</url-pattern>
</servlet-mapping>
<!--
solve messy code
-->
<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>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
3,mySpring-servlet.xml文件
在工程的WEB-INF下面创建dispatcherServlet配置文件[servlet-name]-servlet.xml。
文件名的格式必需为“[servlet-name]-servlet.xml”,比如笔者的web文件里servlet-name为mySpring,则文件名必须为mySpring-servlet.xml,如果放错的位置或是文件名称格式不对,那么通过web.xml文件是找不到dispatcherServlet文件的。也可以说,只要在Web.xml里配置好了DispatcherServlet,那么该DispatcherServlet的名称也就唯一确定了,一个web.xml文件可以映射出多个DispatcherServlet文件。
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="#/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="#/schema/context"
xmlns:jdbc="#/schema/jdbc"
xmlns:jee="#/schema/jee"
xsi:schemaLocation="#/schema/jdbc #/schema/jdbc/spring-jdbc-4.3.xsd
#/schema/jee #/schema/jee/spring-jee-4.3.xsd
#/schema/beans #/schema/beans/spring-beans.xsd
#/schema/context #/schema/context/spring-context-4.3.xsd">
<!--
configure HandlerMapping
-->
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"></bean>
<!--
configure HandlerAdapter
-->
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"></bean>
<!--
configure controller
-->
<bean name="/testSpring.ms" class="com.my.spring.TestSpring"></bean>
<!--
configure viewResolver
-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property ame="viewClass">
<value>org.springframework.web.servlet.view.InternalResourceView</value>
</property>
<property name="prefix" value="/view/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
4,welcome.jsp文件
<%@ 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=utf-8">
<title>Insert title here</title>
</head>
<body>
<form action="testSpring.ms">
input your words:
<input type="text" name="words"/>
<input type="submit" value="提交">
</form>
</body>
</html>
5,result.jsp文件
<%@ 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=utf-8">
<title>Insert title here</title>
</head>
<body>
${myValue}
</body>
</html>
6,TestSpring.java文件
package com.my.spring;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;
public class TestSpring extends AbstractController {
@Override
protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception {
// TODO Auto-generated method stub
String value=request.getParameter("words");
//create model
Map<String,String>model=new HashMap<String,String>();
//set value
model.put("myValue", value);
//create modelAndView
ModelAndView mav=new ModelAndView("result",model);
return mav;
}
}
这个文件必需要实现AbstrcactController抽象类,或是实现Controller接口。然后重写handlerRequestInternal方法。这里一定要选择servlet下的AbstractController或Controller,如果读者选择了portlet,恰好项目下又没有相应的包,那么就会报错。
错误
一,错误一:
错误代码:
The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path
错误解决:
这是因为项目下没有该类,添加servlet-api.jar即可,详见Eclipse如何发布Web项目。
二,错误二:
错误代码:
Server Tomcat v8.5 Server at localhost failed to start.
错误解决:
造成这个错误的原因有许多,这里建议读者检查一下自己的Web.xml文件中的语法是否正确。
三,错误三:
错误代码:
Multiple markers at this line
- The type javax.portlet.ActionResponse cannot be resolved. It is indirectly
referenced from required .class files
- The type javax.portlet.RenderRequest cannot be resolved. It is indirectly
referenced from required .class files
- The type javax.portlet.RenderResponse cannot be resolved. It is indirectly
referenced from required .class files
- The type javax.portlet.ActionRequest cannot be resolved. It is indirectly
referenced from required .class files
- The type javax.portlet.PortletContext cannot be resolved. It is indirectly referenced
from required .class files
问题解决:
这是因为读者的项目下面没有,portlet包导致的,portlet包的下载。
除了引入相应的Portlet包外,这里读者也可以将
import org.springframework.web.portlet.ModelAndView;
import org.springframework.web.portlet.mvc.AbstractController;
改为:
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;
四,错误四:
错误代码:
Handler processing failed; nested exception is java.lang.NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config
错误解决:
导入一个jstl标签库即可