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SpringMVC框架介紹
Spring框架提供了構造Web應用程序的全能MVC模塊。Spring MVC分離了控制器、模型對象、分派器以及處理程序對象的角色,這種分離讓它們更容易進行制定。是一個標準的MVC框架。
SpringMVC框架圖
那你猜一猜哪一部分應該是哪一部分?
SpringMVC接口解釋
DispatcherServlet接口:
Spring提供的前端控制器,所有的請求都有經過它來統一分發。在DispatcherServlet將請求分發給Spring Controller之前,需要藉助於Spring提供的HandlerMapping定位到具體的Controller。
HandlerMapping接口:
能夠完成客戶請求到Controller映射。
Controller接口:
需要爲併發用戶處理上述請求,因此實現Controller接口時,必須保證線程安全並且可重用。Controller將處理用戶請求,這和Struts Action扮演的角色是一致的。一旦Controller處理完用戶請求,則返回ModelAndView對象給DispatcherServlet前端控制器,ModelAndView中包含了模型(Model)和視圖(View)。從宏觀角度考慮,DispatcherServlet是整個Web應用的控制器;從微觀考慮,Controller是單個Http請求處理過程中的控制器,而ModelAndView是Http請求過程中返回的模型(Model)和視圖(View)。
ViewResolver接口:
Spring提供的視圖解析器(ViewResolver)在Web應用中查找View對象,從而將相應結果渲染給客戶。
SpringMVC運行原理
1. 客戶端請求提交到DispatcherServlet
2. 由DispatcherServlet控制器查詢一個或多個HandlerMapping,找到處理請求的Controller
3. DispatcherServlet將請求提交到Controller
4. Controller調用業務邏輯處理後,返回ModelAndView
5. DispatcherServlet查詢一個或多個ViewResoler視圖解析器,找到ModelAndView指定的視圖
6. 視圖負責將結果顯示到客戶端
SpringMVC運行實例
Account類:
package com.pb.entity;
public class Account {
private String cardNo;
private String password;
private float balance;
public String getCardNo() {
return cardNo;
}
public void setCardNo(String cardNo) {
this.cardNo = cardNo;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public float getBalance() {
return balance;
}
public void setBalance(float balance) {
this.balance = balance;
}
}
LoginController類:
package com.pb.web.controller;
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;
import com.pb.entity.Account;
public class LoginController extends AbstractController {
private String successView;
private String failView;//這兩個參數是返回值傳給applicationContext.xml,進行頁面分配
public String getSuccessView() {
return successView;
}
public void setSuccessView(String successView) {
this.successView = successView;
}
public String getFailView() {
return failView;
}
public void setFailView(String failView) {
this.failView = failView;
}
@Override
protected ModelAndView handleRequestInternal(HttpServletRequest request,
HttpServletResponse response) throws Exception {
// TODO Auto-generated method stub
String cardNo=request.getParameter("cardNo");
String password=request.getParameter("password");
Account account =getAccount(cardNo,password);
Map<String ,Object> model=new HashMap<String,Object>();
if(account !=null){
model.put("account", account);
return new ModelAndView(getSuccessView(),model);
}else{
model.put("error", "卡號和密碼不正確");
return new ModelAndView(getFailView(),model);
}
}//本應該這個方法寫在模型層,這地方直接給放在了邏輯層這個地方偷懶了。
public Account getAccount(String cardNo,String password){
if(cardNo.equals("123")&&password.equals("123")){
Account account =new Account();
account.setCardNo(cardNo);
account.setBalance(88.8f);
return account;
}else{
return null;
}
}
}
applicationContext.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: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-2.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
<bean id="loginController" class="com.pb.web.controller.LoginController">
<property name="successView" value="showAccount"></property>
<property name="failView" value="login"></property>
</bean>
<bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
<property name="mappings">
<props>
<prop key="/login.do">loginController</prop>
</props>
</property>
</bean>
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
Jsp頁面:
<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
<a href="login.jsp">進入</a>
</body>
</html>
login.jsp
<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
${error }
<form action="login.do" method="post">
賬號登陸<br>
<hr>
卡號:<input type="text" name="cardNo"><br>
密碼:<input type="text" name="password"><br>
<input type="submit" value="登陸">
</form>
</body>
</html>
showAccount.jsp
<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
賬戶信息<br>
卡號:${account.cardNo }<br>
密碼:${account.password }<br>
錢數:${account.balance }<br>
</body>
</html>
Web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4"> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>Dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>Dispatcher</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> </web-app>
工程原碼:原碼
SpringMVC總結
以上就是我理解的Spring MVC可能不夠深刻。其實對於任何的框架來說,一個框架是一個可複用設計,框架的最大的好處就是複用。每個框架都有存在的理由,那Spring MVC的理由是什麼呢?
只有各個框架之間彼此瞭解他們之間的優缺點,使用場合,使用原理,才能讓我們的更快的成長。