SpringMVC注解应用

注解标记只能应用于类，方法，变量的前面

springMVC实例实现(hello)

1.搭建Spring Web MVC开发环境，引入IOC，webmvc开发包；在src下添加applicationContext.xml

2.在web.xml中配置dispatcherServlet

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
  <servlet>
          <servlet-name>hello</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>
          <!-- 启动服务器的时候，优先级是1 -->
          <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
      <servlet-name>hello</servlet-name>
      <url-pattern>*.do</url-pattern>
  </servlet-mapping>
</web-app>

3.在applicationContext.xml中配置相关组件

A.定义Handlermapping

  <!-- 定义handlermapping -->
   <mvc:annotation-driven/>

B.开启组建扫描Controller

<!-- 开启Controller扫描 -->
   <context:component-scan base-package="com.day04"/>

C.定义配置viewResolver

<!-- 配置ViewResolver -->
   <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
           <property name="prefix" value="/WEB-INF/"></property>
           <property name="suffix" value=".jsp"></property>
   </bean>

完整代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
    http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd">
    
   <!-- 定义handlermapping -->
   <mvc:annotation-driven/>
   
   <!-- 开启Controller扫描 -->
   <context:component-scan base-package="com.day04"/>
   
  <!-- 配置ViewResolver -->
   <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
           <property name="prefix" value="/WEB-INF/"></property>
           <property name="suffix" value=".jsp"></property>
   </bean>
   
</beans>

2.编写和HelloController实现

注意：使用注解取消了实现Controller接口及方法约定，可以允许程序员需要灵活定义业务方法定义request， session...（Controller需要扫描到spring容器，对应类前必须使用@Controller注解）

package com.day04.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.swing.plaf.basic.BasicInternalFrameTitlePane.SystemMenuBar;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import com.day04.entity.user;

@Controller
public class HelloController {
    //进入hello页面
    @RequestMapping("/hello.do")
    public String toHello(){
        return "hello";//返回视图名称
    }
}

注意：@RequestMapping("/xxx.do"):该标记用在Controller业务方法前面

Controller如何使用SpringMVC接受参数

1.利用HttpServletRequest

@Controller
public class LoginController {
        
    //登录按钮处理
    @RequestMapping("/login.do")
    public String checkLogin(HttpServletRequest request){
        String name=request.getParameter("username");
        String password=request.getParameter("password");
        if("root".equals(name)&&"1234".equals(password)){
            return "ok";//正确进入OK.jsp
        }else{
            return "login";//错误进入login.jsp
        }
    }
}
    

2.利用业务方法参数

请求页面：请求参数分别为username和password

<%@ 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></title>
</head>
<body>
    <h1>用户登录</h1>
    <form action="login.do" method="post">
        用户名：<input type="text" name="username"><br>
        密码：<input type="password"><br>
        <input type="submit" value="登录">
    </form>
</body>
</html>

参数名与请求参数key保持一致：参数名一致

public class LoginController {    
    //登录按钮处理
    @RequestMapping("/login.do")
    public String checkLogin(HttpServletRequest request){
        String name=request.getParameter("username");
        String password=request.getParameter("password");
        if("root".equals(name)&&"1234".equals(password)){
            return "ok";//正确进入OK.jsp
        }else{
            return "login";//错误进入login.jsp
        }
    }
    
    //测试使用方法参数接受request信息
    @RequestMapping("/login1.do")
    public String checkLogin1String username,String password){
        System.out.println("------执行checkLogin-------");
        System.out.println("username"+username);
        System.out.println("password"+password);

        return "login";
        
    }
}

 利用@RequestMapping("key"):参数名不一致

//测试使用方法参数接受request信息
    @RequestMapping("/login1.do")
    public String checkLogin1(@RequestParam("username")String name,String password){
        System.out.println("------执行checkLogin-------");
        System.out.println("username"+name);
        System.out.println("password"+password);

        return "login";
        
    }

3.利用实体对象当方法参数

创建一个相关类user

package com.day04.entity;

import java.io.Serializable;

public class user implements Serializable{
    private String username;//保持与请求key一致
    private String password;
    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;
    }

}

直接向Controller传参

@RequestMapping("/login2.do")
    public String checkLogin2(user user){
        System.out.println("--------执行checkLogin--------");
        System.out.println("username"+user.getUsername());
        System.out.println("password"+user.getPassword());
        return "login";
    }

使用建议：少量参数使用业务方法参数；大量参数使用实体对象传参；如果客户端没有格式检查，遇到非字符串参数建议使用HttpServletRequest

Controller如何向响应jsp传值

1.利用HttpServletRequest

2.利用ModelAndView做返回值

package com.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public class HelloController implements Controller{

    public ModelAndView handleRequest(HttpServletRequest request, 
                                      HttpServletResponse response) throws Exception {
            ModelAndView mav=new ModelAndView();
            mav.setViewName("hello");//设置视图名字
            mav.getModel().put("msg", "模型数据");//等价于request.setAttribute("msg","模型数据");
        return mav;
    }
}

3.利用ModelMap方法参数

@RequestMapping("/login3.do")
    public String checkLogin3(String username,String password,ModelMap model){
        if("root".equals(username)&&"1234".equals(password)){
            model.put("user", username);//ok.jsp使用${user}
                        return "ok";
        }else{
            model.put("msg", "用户名或密码错误");
            return "login";
            
        }
    }

 4.使用@ModelAttribute("key")

public String checkLogin(@ModelAttribute("user")String username){
      return "ok";//ok.jsp使用${user}
}

Controller如何使用session

 1.在Controller中定义传入参数HttpSession

@RequestMapping("/login3.do")
    public String checkLogin3(String username,String password,ModelMap model,HttpSession session){
        if("root".equals(username)&&"1234".equals(password)){
            model.put("user", username);//ok.jsp使用${user}
            session.setAttribute("username", username);
            return "ok";
        }else{
            model.put("msg", "用户名或密码错误");
            return "login";
            
        }
    }

2.在相关jsp页面调用

<%@ 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></title>
</head>
<body>
    <h1>ok</h1>
    <h2>${user}登录成功</h2>
    session内容：${sessionScope.username}
</body>
</html>