Spring MVC 入门实例
概述:
springmvc 框架围绕DispatcherServlet这个核心展开,DispatcherServlet是Spring MVC的总控制,它负责截获请求并将其分派给相应的处理器处理。SpringMVC框架包括注解驱动控制器、请求及响应的信息处理、视图解析、本地化解 析、上传文件解析、异常处理以及表单标签绑定等内容。
SpringMVC是主要基于MODEL2实现的技术框架,Model2是经典的MVC(model、view、control)模型在web应用中的变 体,这个改变主要源于HTTP协议的无状态性。Model2的目的和MVC一样,也是利用处理器分离模型、视图和控制,达到不同技术层级间松散层耦合的效 果,提高系统的灵活性,复用性和可维护性。在多数情况下可以将Model2与MVC等同起来。SpringMVC结构如下如图所示。
从接受请求道返回响应,Spring MVC框架的众多组建通力配合、各司其职,有条不紊的完成分内的工作。在整个框架中,DispatcherServlet处于核心位置,它负责协调和
组织不同组件完成请求并返回相应的的工作。和大多数MVC框架一样Spring MVC通过一个前端servlet接收所有的请求,并将具体工作委托给其他组件进行处理,DispatcherServlet就是SpringMVC的前 端Servlet。下面对整个过程做一下介绍。
1)整个过程始于客户端发出的一个HTTP请求,Web应用服务器接收到这个请求,如果匹配DispatcherServlet的请求映射路径(web.xml指定),Web容器将该请求转交给DispatcherServlet处理
2)DispatcherServlet接收到这个请求后,将根据请求的信息(包括URL、HTTP方法、请求报文头、请求参数、Cookie等)及 HandlerMapping的配置找到处理请求的处理器Handler。可将HandlerMapping看成路由控制器,将Handler看成目标主 机。值得注意的是SpringMVC并没有定义一个Handler接口,实际上任何一个Object都可以成为请求处理器。
3)当DispatcherServlet根据HandlerMapping得到对应当前请求的Handler后,通过HandlerAdapter对 Handler进行封装,再以统一的适配器借口调用Handler。HandlerAdapter是SpringMVC的架构级接口,顾名思 义,HandlerAdapter是一个适配器,它用统一的接口对各种Handler方法进行调用。
4)处理器完成业务逻辑的处理后将返回一个ModelAndView给DispatcherServlet,ModelAndView包含了视图逻辑名和模型数据信息。
5)ModelAndView中包含的是“逻辑视图名”而非真正的视图对象,DispatcherServlet借由ViewResolver完成逻辑视图名到真实视图对象的解析工作。
6)当得到真实的视图对象View后,DispatcherServlet就使用这个View对象对ModelAndView中的模型数据进行视图渲染。
7)最终客户端得到的响应信息,可能是一个普通的HTML页面,也可能是一个XML活JSON串,甚至是一张图片或一个PDF文档等不同的媒体形式。
下面是一个用户登录的实例。
登录的实例
1环境准备
DROP DATABASE IF EXISTS sampledb; CREATE DATABASE sampledb DEFAULT CHARACTER SET utf8; USE sampledb; ##创建用户表 CREATE TABLE t_user ( user_id INT AUTO_INCREMENT PRIMARY KEY, user_name VARCHAR(30), credits INT, password VARCHAR(32), last_visit datetime, last_ip VARCHAR(23) )ENGINE=InnoDB; ##创建用户登录日志表 CREATE TABLE t_login_log ( login_log_id INT AUTO_INCREMENT PRIMARY KEY, user_id INT, ip VARCHAR(23), login_datetime datetime )ENGINE=InnoDB; ##插入初始化数据 INSERT INTO t_user (user_name,password) VALUES('admin','123456'); COMMIT;
用到的jar文件(Spring3.0以上的jar基本都可以通过,不一定是如下的jar包):
2持久层
package com.baobaotao.domain; import java.io.Serializable; import java.util.Date; public class User implements Serializable{ private int userId; private String userName; private String password; private int credits; private String lastIp; private Date lastVisit; public String getLastIp() { return lastIp; } public void setLastIp(String lastIp) { this.lastIp = lastIp; } public Date getLastVisit() { return lastVisit; } public void setLastVisit(Date lastVisit) { this.lastVisit = lastVisit; } public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public int getCredits() { return credits; } public void setCredits(int credits) { this.credits = credits; } }LoginLog.java
package com.baobaotao.domain; import java.io.Serializable; import java.util.Date; public class LoginLog implements Serializable{ private int loginLogId; private int userId; private String ip; private Date loginDate; public String getIp() { return ip; } public void setIp(String ip) { this.ip = ip; } public Date getLoginDate() { return loginDate; } public void setLoginDate(Date loginDate) { this.loginDate = loginDate; } public int getLoginLogId() { return loginLogId; } public void setLoginLogId(int loginLogId) { this.loginLogId = loginLogId; } public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } }
通过SpringJDBC实现DAO类。UserDao.java
package com.baobaotao.dao; import java.sql.ResultSet; import java.sql.SQLException; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.jdbc.core.RowCallbackHandler; import org.springframework.stereotype.Repository; import com.baobaotao.domain.User; @Repository public class UserDao { @Autowired private JdbcTemplate jdbcTemplate; public int getMatchCount(String userName, String password) { String sqlStr = " SELECT count(*) FROM t_user " + " WHERE user_name =? and password=? "; return jdbcTemplate.queryForInt(sqlStr, new Object[] { userName, password }); } public User findUserByUserName(final String userName) { String sqlStr = " SELECT user_id,user_name,credits " + " FROM t_user WHERE user_name =? "; final User user = new User(); jdbcTemplate.query(sqlStr, new Object[] { userName }, new RowCallbackHandler() { @Override public void processRow(ResultSet rs) throws SQLException { user.setUserId(rs.getInt("user_id")); user.setUserName(userName); user.setCredits(rs.getInt("credits")); } }); return user; } public void updateLoginInfo(User user) { String sqlStr = " UPDATE t_user SET last_visit=?,last_ip=?,credits=? " + " WHERE user_id =?"; jdbcTemplate.update(sqlStr, new Object[] { user.getLastVisit(), user.getLastIp(),user.getCredits(),user.getUserId()}); } }
LoginLogDao.java
package com.baobaotao.dao; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.stereotype.Repository; import com.baobaotao.domain.LoginLog; @Repository public class LoginLogDao { @Autowired private JdbcTemplate jdbcTemplate; public void insertLoginLog(LoginLog loginLog) { String sqlStr = "INSERT INTO t_login_log(user_id,ip,login_datetime) " + "VALUES(?,?,?)"; Object[] args = { loginLog.getUserId(), loginLog.getIp(), loginLog.getLoginDate() }; jdbcTemplate.update(sqlStr, args); } }
然后在Spring中装配DAO。这部分和Service的装配在同一份配置文件中将在后面列出。
3业务层
package com.baobaotao.service; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.baobaotao.dao.LoginLogDao; import com.baobaotao.dao.UserDao; import com.baobaotao.domain.LoginLog; import com.baobaotao.domain.User; @Service public class UserService { @Autowired private UserDao userDao; @Autowired private LoginLogDao loginLogDao; public boolean hasMatchUser(String userName, String password) { int matchCount =userDao.getMatchCount(userName, password); return matchCount > 0; } public User findUserByUserName(String userName) { return userDao.findUserByUserName(userName); } public void loginSuccess(User user) { user.setCredits( 5 + user.getCredits()); LoginLog loginLog = new LoginLog(); loginLog.setUserId(user.getUserId()); loginLog.setIp(user.getLastIp()); loginLog.setLoginDate(user.getLastVisit()); userDao.updateLoginInfo(user); loginLogDao.insertLoginLog(loginLog); } }
然后在Spring中装配Service。即在applicationContext.xml文件,进行如下的更改。这里同时列出了对Dao的装配。
<?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" 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-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/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <!-- 扫描类包,将标注Spring注解的类自动转化Bean,同时完成Bean的注入 --> <context:component-scan base-package="com.baobaotao.dao"/> <context:component-scan base-package="com.baobaotao.service"/> <!-- 配置数据源 --> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="com.mysql.jdbc.Driver" p:url="jdbc:mysql://localhost:3306/sampledb" p:username="root" p:password="526156" /> <!-- 配置Jdbc模板 --> <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate" p:dataSource-ref="dataSource" /> <!-- 配置事务管理器 --> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" p:dataSource-ref="dataSource" /> <!-- 通过AOP配置提供事务增强,让service包下所有Bean的所有方法拥有事务 --> <aop:config proxy-target-class="true"> <aop:pointcut id="serviceMethod" expression=" execution(* com.baobaotao.service..*(..))" /> <aop:advisor pointcut-ref="serviceMethod" advice-ref="txAdvice" /> </aop:config> <tx:advice id="txAdvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="*" /> </tx:attributes> </tx:advice> </beans>
4展现层
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </context-param> <listener> <listener-class> org.springframework.web.context.ContextLoaderListener </listener-class> </listener> <servlet> <servlet-name>baobaotao</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>3</load-on-startup> </servlet> <servlet-mapping> <servlet-name>baobaotao</servlet-name> <url-pattern>*.html</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
上述配置文件中的servlet-name为baobaotao,则在/WEB-INF下必须提供一个以baobaotao-servlet.xml的配 置文件,这是spring mvc框架的契约。这个配置文件无需通过web.xml的contextConfigLocation上下文参数进行声明,因为Spring MVC的Servlet会自动将baobaotao-servlet.xml和Spring其它的配置文件进行拼装。
package com.baobaotao.web; import java.util.Date; import javax.servlet.http.HttpServletRequest; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.servlet.ModelAndView; import com.baobaotao.domain.User; import com.baobaotao.service.UserService; @Controller public class LoginController{ @Autowired private UserService userService; @RequestMapping(value = "/index.html") public String loginPage(){ return "login"; } @RequestMapping(value = "/loginCheck.html") public ModelAndView loginCheck(HttpServletRequest request,LoginCommand loginCommand){ boolean isValidUser = userService.hasMatchUser(loginCommand.getUserName(), loginCommand.getPassword()); if (!isValidUser) { return new ModelAndView("login", "error", "用户名或密码错误。"); } else { User user = userService.findUserByUserName(loginCommand .getUserName()); user.setLastIp(request.getLocalAddr()); user.setLastVisit(new Date()); userService.loginSuccess(user); request.getSession().setAttribute("user", user); return new ModelAndView("main"); } } }
这里利用了一个默认契约绑定的类LoginCommand.java
package com.baobaotao.web; public class LoginCommand { private String userName; private String password; public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } }
ModelAndView的解析配置:
<?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-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- 扫描web包,应用Spring的注解 --> <context:component-scan base-package="com.baobaotao.web"/> <!-- 配置视图解析器,将ModelAndView及字符串解析为具体的页面 --> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:viewClass="org.springframework.web.servlet.view.JstlView" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> </beans>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <html> <head> <title>宝宝淘论坛登录</title> </head> <body> <c:if test="${!empty error}"> <font color="red"><c:out value="${error}" /></font> </c:if> <form action="<c:url value="loginCheck.html"/>" method="post"> 用户名: <input type="text" name="userName"> <br> 密 码: <input type="password" name="password"> <br> <input type="submit" value="登录" /> <input type="reset" value="重置" /> </form> </body> </html>main.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>宝宝淘论坛</title> </head> <body> ${user.userName},欢迎您进入宝宝淘论坛,您当前积分为${user.credits}; </body> </html>
最后部署运行即可。