第二篇 -- 写一个登录界面

第一篇讲了如何写一个HelloWorld程序，今天了解一下如何写一个登录界面。

一、准备MySQL数据

方法1. 通过命令行创建

第1步：查看数据库

 第二步：新建一个user的数据库（用来存放用户信息）

 

 第三步：创建一个user表格（存放ID，用户名和密码）

 第三步：给表中添加数据

方法2. 通过MySQL Workbench添加

第一步：先认识MySQL Workbench界面

 可以看到数据库有user，就是刚刚用命令行创建的一个数据库

第二步：创建数据库

点击apply，可以看到多了一个userui的数据库

 第三步：创建数据表

第四步：看下之前cmd版创建的user表格式是怎样的

 第五步：配置数据表

 点击Apply，可以看到user已经创建好了。

 

 第六步：瞧一瞧user表里的数据，并添加数据

 好了，MySQL Workbench添加数据库的方法也了解了，数据库现在已经Ready了。

二、实现登录页面程序

第一步：按照上篇介绍新建一个HelloWorld项目并能运行成功。

（乱码问题上节讲过，这里不重要）

 第二步：将页面访问主页定位到登录页面并编写登录页面

在HomeController.java中指定登录页面为login

在views文件夹新建一个jsp文件

 

 

 login.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ page session="false"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    import="java.util.*" pageEncoding="UTF-8"%>
<html>
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="description" content="">
    <meta name="author" content="">

    <title>Login</title>
    
</head>
<body>


    <form role="form" action="index" method="post">
        <fieldset>
            <div class="form-group">
                <label for="name">Name: </label>
                <input class="form-control" placeholder="Name" name="name" type="name" style="font-size: 16px;text-align:left;" maxlength="30">
            </div>
            <div class="form-group">
                <label for="password">Password: </label>
                <input class="form-control" placeholder="Password" name="password" type="password" style="font-size: 16px;text-align:left;" maxlength="30">
            </div>
                                    
            <div align="center" class="form-group">
                <button type="submit" class="btn btn-lg btn-success btn-default btn-block" name="Login">Login</button>
            </div>
                                    
            <p style="font-size: 14px; line-height: 150%; font-family: consolas;">
                <font color="red">${Error}</font>
            </p>
        </fieldset>
    </form>


</body>

</html>
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然后运行一遍代码，可以看到结果

 第三步：获取用户输入的数据

 在HomeController.java中添加

然后运行程序，输入账号密码，点击Login按钮，看是否触发这个函数，打印出account

 

 可以看到成功打印出你输的账户信息，那么接下来就是连接到数据库去查找有没有这个用户了。

第四步：连接已经准备好的数据库。

1. 右键LoginPage项目，【New】-->【Package】，Name就填com.free.entity。

2. 在com.free.entity下新建一个User.java，右键com.free.entity，【New】--> 【Class】，Name就填User。当然java的名称自己可以取的。这个文件对应前面数据库中的数据（id, name, password）

User.java

package com.free.entity;

public class User {
    private Integer id;
    private String name;
    private String password;
    
    public Integer getuser_id() {
        return id;
    }
    public void setuser_id(Integer User_id) {
        id = User_id;
    }
    public String getuser_name() {
        return name;
    }
    public void setuser_name(String User_name) {
        name = User_name;
    }

    public String getpassword() {
        return password;
    }
    public void setpassword(String Password) {
        password = Password;
    }

    
    public User(Integer User_id, String User_name,  String Password) {
        super();
        id = User_id;
        name = User_name;
        password = Password;
    }
    
}
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3. 新建一个com.free.dao包，在其下新建一个UserDao.java，用来写操作数据库的方法接口

UserDao.java

package com.free.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.free.entity.User;

public interface UserDao {

    User login(@Param("name") String name,@Param("password") String password); //这个地方的name和Usermapper里面login中select语句#{name}对应
}
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4. 新建一个com.free.mapper，实现UserDao里面的方法，这里用到了mybatis。在com.free.mapper下新建一个Usermapper.xml文件，【New】--> 【Other】--> 【Web】--> 【XML File】，取名为Usermapper。

Usermapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-mapper.dtd" >

<mapper namespace="com.free.dao.UserDao">
    <resultMap id="user" type="com.free.entity.User">
        <id column="id" property="id" jdbcType="INTEGER" />
        <result column="name" property="name" jdbcType="VARCHAR" />
        <result column="password" property="password" jdbcType="VARCHAR" />
    </resultMap>

    <select id="login" resultMap="user">
        SELECT * FROM user 
        WHERE name=#{name} 
            AND password=#{password};
    </select>

</mapper>
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5. 配置mybatis和mysql

在src/main/resources下建立一个mybatis的文件夹，右键src/main/resources，【New】--> 【Folder】，Name就填mybatis。

在mybatis文件夹下新建mybatis的配置文件，右键mybatis，【New】-->【Other】--> 【MyBatis】--> 【MyBatis XML Mapper】，取名为mybatis-config。

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"  
"http://mybatis.org/dtd/mybatis-3-config.dtd"> 
<configuration>    
</configuration>
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在src/main/resources下面新建一个properties文件夹，在此文件夹下建立一个jdbc.properties文件，【New】--> 【File】，取名为jdbc.properties。

jdbc.properties

jdbc_driverClassName=com.mysql.jdbc.Driver
jdbc_url=jdbc:mysql://127.0.0.1:3306/user?useUnicode=true&characterEncoding=utf8
jdbc_username=root
jdbc_password=password
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修改pom.xml, srcmainwebappWEB-INFweb.xml, srcmainwebappWEB-INFspring oot-context.xml, srcmainwebappWEB-INFspringappServletservlet-context.xml

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.free</groupId>
    <artifactId>loginpage</artifactId>
    <name>loginpage</name>
    <packaging>war</packaging>
    <version>1.0.0-BUILD-SNAPSHOT</version>
    <properties>
        <java-version>1.6</java-version>
        <org.springframework-version>4.2.6.RELEASE</org.springframework-version>
        <org.aspectj-version>1.8.9</org.aspectj-version>
        <org.slf4j-version>1.7.5</org.slf4j-version>
    </properties>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${org.springframework-version}</version>
            <exclusions>
                <!-- Exclude Commons Logging in favor of SLF4j -->
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                 </exclusion>
            </exclusions>
        </dependency>
        
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>
        
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>
    
       <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>
        
        <!-- AspectJ -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>${org.aspectj-version}</version>
        </dependency>    
        
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>${org.aspectj-version}</version>
        </dependency>
        
        <!-- Logging -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${org.slf4j-version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>${org.slf4j-version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${org.slf4j-version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.15</version>
            <exclusions>
                <exclusion>
                    <groupId>javax.mail</groupId>
                    <artifactId>mail</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>javax.jms</groupId>
                    <artifactId>jms</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jdmk</groupId>
                    <artifactId>jmxtools</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jmx</groupId>
                    <artifactId>jmxri</artifactId>
                </exclusion>
            </exclusions>
            <scope>runtime</scope>
        </dependency>

        <!-- @Inject -->
        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <version>1</version>
        </dependency>
                
        <!-- Servlet -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
    
        <!-- Test -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.7</version>
            <scope>test</scope>
        </dependency> 
        
        <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-databind</artifactId>
          <version>2.7.4</version>
          <exclusions>
            <exclusion>
              <groupId>com.fasterxml.jackson.core</groupId>
              <artifactId>jackson-core</artifactId>
            </exclusion>
            <exclusion>
              <groupId>com.fasterxml.jackson.core</groupId>
              <artifactId>jackson-annotations</artifactId>
           </exclusion>
         </exclusions>
       </dependency>
       
        <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-core</artifactId>
             <version>2.7.4</version>
       </dependency>
 
       <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
             <version>2.7.4</version>
       </dependency>
     
     
       <dependency>
            <groupId>net.sf.json-lib</groupId>
            <artifactId>json-lib</artifactId>
            <version>2.4</version>
            <classifier>jdk15</classifier>
        </dependency>
        
        <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>4.2.6.RELEASE</version>
    </dependency>
        
         <!-- mybatis 包 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.0</version>
        </dependency>

        <!--mybatis spring 插件 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.3.0</version>
        </dependency>

        <!-- mysql连接 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.13</version>
        </dependency>
        
        <dependency>  
           <groupId>com.itextpdf</groupId>  
           <artifactId>itextpdf</artifactId>  
           <version>5.5.0</version>  
         </dependency>  
         <dependency>  
           <groupId>com.itextpdf</groupId>  
           <artifactId>itext-pdfa</artifactId>  
           <version>5.5.0</version>  
         </dependency>  
         <dependency>  
           <groupId>com.itextpdf</groupId>  
           <artifactId>itext-asian</artifactId>  
           <version>5.2.0</version>  
         </dependency>   
         <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.10-FINAL</version>
        </dependency>
        <!-- POI -->
        <!-- xls view -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.14</version>
        </dependency>

        <!-- xlsx view -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.14</version>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.9</version>
                <configuration>
                    <additionalProjectnatures>
                        <projectnature>org.springframework.ide.eclipse.core.springnature</projectnature>
                    </additionalProjectnatures>
                    <additionalBuildcommands>
                        <buildcommand>org.springframework.ide.eclipse.core.springbuilder</buildcommand>
                    </additionalBuildcommands>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.5.1</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                    <compilerArgument>-Xlint:all</compilerArgument>
                    <showWarnings>true</showWarnings>
                    <showDeprecation>true</showDeprecation>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <configuration>
                    <mainClass>org.test.int1.Main</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>
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web.xml

<?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">

    <!-- The definition of the Root Spring Container shared by all Servlets 
        and Filters -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/root-context.xml</param-value>
    </context-param>

    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    
    <filter>
    <filter-name>CharacterEncodingFilter</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>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <!-- Processes application requests -->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    
    <servlet>
        <display-name>UploadServlet</display-name>
        <servlet-name>UploadServlet</servlet-name>
        <servlet-class>com.free.loginpage.UploadServlet</servlet-class>
      </servlet>
   
      <servlet-mapping>
           <servlet-name>UploadServlet</servlet-name>
           <url-pattern>/loginpage/UploadServlet</url-pattern>
     </servlet-mapping>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.js</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.css</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.ttf</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.woff</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.woff2</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
            <servlet-name>default</servlet-name>
            <url-pattern>*.gif</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
            <servlet-name>default</servlet-name>
            <url-pattern>*.jpg</url-pattern>
      </servlet-mapping>
      
      <servlet-mapping>
            <servlet-name>default</servlet-name>
         <url-pattern>*.png</url-pattern>
       </servlet-mapping>

</web-app>
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root-context.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:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop.xsd">
    
    <!-- Root Context: defines shared resources visible to all other web components -->
    <!-- 引入jdbc配置文件 -->  
     <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
               <value>classpath:properties/*.properties</value>
            </list>
        </property>
    </bean>
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.free.dao" />
    </bean>
    
    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        
        <property name="driverClassName">
            <value>${jdbc_driverClassName}</value>
        </property>
        <property name="url">
            <value>${jdbc_url}</value>
        </property>
        <property name="username">
            <value>${jdbc_username}</value>
        </property>
        <property name="password">
            <value>${jdbc_password}</value>
        </property>
    </bean>
    
    <!--      配置Mybatis文件 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="mapperLocations" value="classpath*:com/free/mapper/**/*.xml"/>  
        <property name="configLocation" value="classpath:mybatis/mybatis-config.xml" />
    </bean>
    
</beans>
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sevlet-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <!-- DispatcherServlet Context: defines this servlet's request-processing 
        infrastructure -->

    <!-- Enables the Spring MVC @Controller programming model -->
    <annotation-driven />

    <!-- Handles HTTP GET requests for /resources/** by efficiently serving 
        up static resources in the ${webappRoot}/resources directory -->
    <resources mapping="/resources/**" location="/resources/" />

    <!-- Resolves views selected for rendering by @Controllers to .jsp resources 
        in the /WEB-INF/views directory -->
    <beans:bean
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>
    
    <!-- File Upload -->
    <beans:bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">  
        <beans:property name="maxUploadSize">  
            <beans:value>10485760</beans:value>  
        </beans:property>  
        <beans:property name="defaultEncoding">
            <beans:value>UTF-8</beans:value>
        </beans:property>
    </beans:bean>

    <!-- 自动扫描controller -->
    <context:component-scan base-package="com.free.loginpage" />

    <!-- 自动扫描的service -->
    <context:component-scan base-package="com.free.service" />
    

</beans:beans>
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注意，因为我用的mysql的版本是mysql-8.0.12-winx64，所以在pom.xml中配置的mysql-connection-java版本是8.0.13，这里需要跟自己的mysql版本对应

6. 新建一个com.free.service包，在com.free.service包下建一个UserService.java，作为一个用户登陆接口。右键com.free.service，【New】--> 【Class】，Name就填UserService。当然java的名称自己可以取的。

UserService.java

package com.free.service;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.free.entity.User;

public interface UserService {

    User login(String name,String password);
}
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7. 在com.free.service包下建一个UserServiceImpl.java，实现UserService的函数。

UserServiceImpl.java

package com.free.service;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import com.free.dao.UserDao;
import com.free.entity.User;

@Service
public class UserServiceImpl implements UserService {
    
    @Resource
    public UserDao userDao;
    
    @Override
    public User login(String name,String password) {
        
        return userDao.login(name,password);
    }

}
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8. 修改HomeController.java中的登录函数。

HomeController.java

package com.free.loginpage;

import java.text.DateFormat;
import java.util.Date;
import java.util.Locale;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView; 
import org.springframework.web.servlet.mvc.support.RedirectAttributes;  
import org.springframework.web.bind.annotation.SessionAttributes;  

import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;

import javax.annotation.Resource;

import com.free.entity.User;
import com.free.service.UserService;

/**
 * Handles requests for the application home page.
 */
@Controller
@SessionAttributes("User")
public class HomeController {
    
    private static final Logger logger = LoggerFactory.getLogger(HomeController.class);
    
    @Resource
    public UserService userService;
    
    /**
     * Simply selects the home view to render by returning its name.
     */
    
    @RequestMapping(value = "/")
    public String ShowLogin() 
    {
        return "login";
    }
    
    @RequestMapping(value = "/login")
    public String logout(HttpServletRequest request){
        Enumeration<String> em = request.getSession().getAttributeNames();
         while(em.hasMoreElements())
         {
             request.getSession().removeAttribute(em.nextElement().toString());
         }
         request.getSession().invalidate();
          
          return "login";
    }
    
    // 点击login时触发
    
    @RequestMapping(value = "/index", params="Login", method = RequestMethod.POST)
    public ModelAndView Login(HttpServletRequest request,Locale locale, Model model,ModelAndView view, RedirectAttributes redirectAttributes)
    {  
        
        String name = request.getParameter("name");  
        String password = request.getParameter("password"); 
        logger.info(name);
        User user = userService.login(name, password); 
        
        if(user != null)
        {
            model.addAttribute("User", user);

            view.setViewName("redirect:/index");
        }
        else
        {
            redirectAttributes.addFlashAttribute("Error", " * Wrong name or password.");
            view.setViewName("redirect:/login");
        }
        
        return  view;
    }
    
    @RequestMapping(value = "/index")
    public ModelAndView ShowIndex(@ModelAttribute("User") User user, Locale locale, Model model,ModelAndView view) 
    { 
        //get current time        
        
        view.setViewName("index");
        
        return view;
    }
}
View Code

9. 最后，直接将原先写HelloWorld对应的Home.jsp重命名为index，然后运行程序。

包结构

效果图：

 

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原文地址：https://www.cnblogs.com/smart-zihan/p/15041013.html