SSM框架的整合与使用——实现简单的转账系统

一、整合思路

　　SSM框架即SpringMVC + Spring + MyBati框架集，是一种轻量级的Web开源框架。它们各自在JAVA三层架构中负责的模块如下图所示：

　　其中，SpringMVC与Spring之间本就存在包含关系，所以它们之间并不需要整合，只需要在web.xml中配置使用即可。而SpringMVC并不和MyBatis直接交互，因此它们之间也不需要进行配置。只有Spring和MyBatis二者之间，我们需要用Spring来将MyBatis整合进来。

　　因此，我们只需要对web.xml和Spring的配置文件进行一些额外的配置即可。

　　下面，我们通过实现一个简单的转账系统，来展示SSM框架的整合和使用。

二、SSM框架整合

　　首先新建一个JavaWeb项目，导入SpringMVC、Spring、MyBatis三个框架的jar包和它们之间整合所需要的jar包。

　　在src目录下创建controller、dao、service、pojo四个包，分别用来存放控制层、持久层、业务层、普通java类的代码。

　　配置web.xml，使项目加载SpringMVC和Spring。

 1 xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
 3   <display-name>SSMdisplay-name>
 4   <welcome-file-list>
 5     <welcome-file>index.htmlwelcome-file>
 6     <welcome-file>index.htmwelcome-file>
 7     <welcome-file>index.jspwelcome-file>
 8     <welcome-file>default.htmlwelcome-file>
 9     <welcome-file>default.htmwelcome-file>
10     <welcome-file>default.jspwelcome-file>
11   welcome-file-list>
12   
13   <servlet>
14       <servlet-name>SpringMVCservlet-name>
15       <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
16       <load-on-startup>1load-on-startup>
17   servlet>
18   
19   <servlet-mapping>
20       <servlet-name>SpringMVCservlet-name>
21       <url-pattern>/url-pattern>
22   servlet-mapping>
23   
24   <listener>
25       <listener-class>org.springframework.web.context.ContextLoaderListenerlistener-class>
26   listener>
27   
28   <context-param>
29       <param-name>contextConfigLocationparam-name>
30       <param-value>classpath:applicationContext.xmlparam-value>
31   context-param>
32   
33   <filter>
34       <filter-name>characterEncodingFilterfilter-name>
35       <filter-class>org.springframework.web.filter.CharacterEncodingFilterfilter-class>
36       <init-param>
37           <param-name>encodingparam-name>
38           <param-value>UTF-8param-value>
39       init-param>
40   filter>
41   <filter-mapping>
42       <filter-name>characterEncodingFilterfilter-name>
43       <url-pattern>/*url-pattern>
44   filter-mapping>
45 web-app>

　　在WEB-INF中创建SpringMVC配置文件SpringMVC-servlet.xml（也可以将配置文件放到其他位置，但需要在web.xml中指明配置文件的路径）和jsp文件夹，jsp文件夹用来存放jsp页面。

 1 xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xmlns:context="http://www.springframework.org/schema/context"
 5     xsi:schemaLocation="
 6         http://www.springframework.org/schema/beans
 7         http://www.springframework.org/schema/beans/spring-beans.xsd
 8         http://www.springframework.org/schema/context
 9         http://www.springframework.org/schema/context/spring-context.xsd">
10     
11     <context:component-scan base-package="controller" />
12     
13     <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
14         <property name="prefix" value="/WEB-INF/jsp/"/>
15         <property name="suffix" value=".jsp"/>
16     bean>
17 beans>

　　在src目录下创建Spring的配置文件applicationContext.xml（文件路径在web.xml中指定），配置Spring并加载MyBatis。

 1 xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xmlns:context="http://www.springframework.org/schema/context"
 5     xmlns:tx="http://www.springframework.org/schema/tx"
 6     xsi:schemaLocation="http://www.springframework.org/schema/beans
 7         https://www.springframework.org/schema/beans/spring-beans.xsd
 8         http://www.springframework.org/schema/context
 9         http://www.springframework.org/schema/context/spring-context.xsd
10         http://www.springframework.org/schema/tx
11         http://www.springframework.org/schema/tx/spring-tx.xsd">
12     
13     <context:component-scan base-package="service"/>
14     
15     <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
16             <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
17             <property name="url" value="jdbc:mysql://localhost:3306/user?serverTimezOne=Asia/Shanghai"/>
18             <property name="username" value="root"/>
19             <property name="password" value="root"/>
20     bean>
21     
22     <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
23         <property name="dataSource" ref="dataSource"/>
24         <property name="configLocation" value="classpath:dao/mybatis-config.xml"/>
25     bean>
26     
27     <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
28         <property name="basePackage" value="dao"/>
29         <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
30     bean>
31     
32     <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
33         <property name="dataSource" ref="dataSource"/>
34     bean>
35     
36     <tx:annotation-driven transaction-manager="txManager"/>
37 beans>

　　在dao包里创建MyBatis的配置文件mybatis-config.xml（文件路径在Spring配置文件中指定），指明MyBatis映射文件的路径。

1 xml version="1.0" encoding="UTF-8"?>
2 DOCTYPE configuration
3     PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
4     "http://mybatis.org/dtd/mybatis-3-config.dtd">
5 <configuration>
6     <mappers>
7         <mapper resource="dao/UserMapper.xml"/>
8     mappers>
9 configuration>

　　在dao包中创建MyBatis的映射文件UserMapper.xml，用来后面实现转账系统时使用。

　　到了这里，SSM框架环境就已经搭建完成了，可以开始编写代码来实现转账系统了。整合后总的目录结构如下所示：

三、转账系统实现

　　我们要实现的转账系统很简单，该系统具体的操作流程就是“注册——登录——转账”，用户注册后，默认有100元的余额，然后就可以登陆系统，给指定的用户转账。虽然系统简单，但包含了SSM框架中最基础的部分。

1、实现持久层

　　经过分析，我们要实现这样的转账系统，首先需要一个记录用户信息的表，因此我们在数据库中，创建一个user库和一个user表，表定义如下：

1 CREATE TABLE `user`  (
2   `id` int(11) NOT NULL AUTO_INCREMENT,
3   `username` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
4   `password` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
5   `sum` int(11) NOT NULL DEFAULT 100,
6   PRIMARY KEY (`id`) USING BTREE
7 ) ENGINE = InnoDB AUTO_INCREMENT = 10 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

　　并插入几条初始数据。

　　在pojo包中，创建一个跟user表字段对应的类User.java，便于我们传递数据。

 1 package pojo;
 2 
 3 public class User {
 4     
 5     private int id;
 6     
 7     private String username;
 8 
 9     private String password;
10     
11     private int sum;
12 
13     public int getId() {
14         return id;
15     }
16     
17     public void setId(int id) {
18         this.id = id;
19     }
20     
21     public String getUsername() {
22         return username;
23     }
24 
25     public void setUsername(String username) {
26         this.username = username;
27     }
28 
29     public String getPassword() {
30         return password;
31     }
32 
33     public void setPassword(String password) {
34         this.password = password;
35     }
36     
37     public int getSum() {
38         return sum;
39     }
40 
41     public void setSum(int sum) {
42         this.sum = sum;
43     }
44 
45     @Override
46     public String toString() {
47         return "User [id=" + id + ", username=" + username + ", password=" + password + ", sum=" + sum + "]";
48     }
49 
50 }

　　在前面创建的MyBatis映射文件UserMapper.xml中，写好需要的SQL语句。

 1 xml version="1.0" encoding="UTF-8"?>
 2 DOCTYPE mapper
 3     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="dao.UserDao">
 6     <select id="selectUserByNameAndPass" resultType="pojo.User" parameterType="pojo.User">
 7         select * from user where username = #{username} and password = #{password}
 8     select>
 9     <select id="selectUserByName" resultType="pojo.User" parameterType="pojo.User">
10         select * from user where username = #{username}
11     select>
12     <insert id="addUser" parameterType="pojo.User">
13         insert into user (username,password) values (#{username},#{password})
14     insert>
15     <update id="updateSumByName" parameterType="pojo.User">
16         update user set sum = #{sum} where username = #{username}
17     update>
18 mapper>

　　在dao包中创建UserDao.java接口，编写MyBatis映射接口。

 1 package dao;
 2 
 3 import org.apache.ibatis.annotations.Mapper;
 4 
 5 import pojo.User;
 6 
 7 @Mapper
 8 public interface UserDao {
 9 
10     public User selectUserByNameAndPass(User user);
11     
12     public int addUser(User user);
13     
14     public User selectUserByName(User user);
15     
16     public int updateSumByName(User user);
17 }

　　到这里持久层就编写完成了，此时的目录结构如下：

2、实现业务层

　　经过分析，该系统需要实现的业务有三个，分别是“登录”、“注册”和“转账”。我们可以在service包下创建UserService.java类，用三个方法来实现这些业务。代码如下：

 1 package service;
 2 
 3 import javax.servlet.http.HttpSession;
 4 
 5 import org.springframework.beans.factory.annotation.Autowired;
 6 import org.springframework.stereotype.Service;
 7 import org.springframework.transaction.annotation.Transactional;
 8 
 9 import dao.UserDao;
10 import pojo.User;
11 
12 @Service
13 public class UserService {
14     
15     @Autowired
16     private UserDao userDao;
17     
18     @Autowired
19     private HttpSession httpSession;
20     
21     public boolean login(User user) {
22         //验证账号密码
23         user = userDao.selectUserByNameAndPass(user);
24         if (user == null) {
25             return false;
26         }
27         //设置Session
28         httpSession.invalidate();
29         httpSession.setAttribute("username", user.getUsername());
30         return true;
31     }
32     
33     public boolean register(User user) {
34         //检查用户名是否重复
35         if (userDao.selectUserByName(user) != null) {
36             return false;
37         }
38         userDao.addUser(user);
39         return true;
40     }
41     
42     @Transactional
43     public boolean transfer(User user_in) {
44         //检查是否自己向自己转账
45         if (((String) httpSession.getAttribute("username")).equals(user_in.getUsername())) {
46             return false;
47         }
48         //检查转账金额是否为正数
49         int transferSum = user_in.getSum();
50         if (transferSum <= 0) {
51             return false;
52         }
53         //检查转账目标用户是否存在
54         user_in = userDao.selectUserByName(user_in);
55         if (user_in == null) {
56             return false;
57         }
58         //检查用户是否有足够的余额进行转账
59         User user_out = new User();
60         user_out.setUsername((String) httpSession.getAttribute("username"));
61         user_out = userDao.selectUserByName(user_out);
62         int remainSum = user_out.getSum() - transferSum;
63         if ( remainSum <0) {
64             return false;
65         }
66         //开始转账
67         user_out.setSum(remainSum);
68         userDao.updateSumByName(user_out);
69         user_in.setSum(user_in.getSum() + transferSum);
70         userDao.updateSumByName(user_in);
71         return true;
72     }
73 }

三、实现控制层

　　跟业务层一样，控制层也需要三个控制器来调用业务层。我们在controller包中创建UserController.java类，同样需要编写三个方法，代码如下：

 1 package controller;
 2 
 3 import org.springframework.beans.factory.annotation.Autowired;
 4 import org.springframework.stereotype.Controller;
 5 import org.springframework.web.bind.annotation.RequestMapping;
 6 
 7 import pojo.User;
 8 import service.UserService;
 9 
10 @Controller
11 public class UserController {
12     
13     @Autowired
14     private UserService userService;
15     
16     @RequestMapping("/login")
17     public String login(User user) {
18         if(!userService.login(user)) {
19             return "LoginError";
20         }
21         return "Transfer";
22     }
23     
24     @RequestMapping("/register")
25     public String register(User user) {
26         if(userService.register(user)) {
27             return "RegisterSuccess";
28         }
29         return "RegisterError";
30     }
31     
32     @RequestMapping("/transfer")
33     public String transfer(User user) {
34         if (userService.transfer(user)) {
35             return "TransferSuccess";
36         }
37         return "TransferError";
38     }
39 }

4、实现视图层

　　根据控制层中的定义，我们总共需要编写七个jsp页面，分别如下：

　　登录注册页面login.jsp：

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>登录title>
 8 head>
 9 <body>
10     <form action="${pageContext.request.contextPath}/login" method="post">
11         <table>
12             <tr>
13                 <td align="right">用户名：td>
14                 <td><input type="text" name="username"/>td>
15             tr>
16             <tr>
17                 <td align="right">密码：td>
18                 <td><input type="password" name="password"/>td>
19             tr>
20             <tr>
21                 <td align="center" colspan="2"><input type="submit" value="登录"/><input type="submit" value="注册" formaction="${pageContext.request.contextPath}/register"/>td>
22             tr>
23         table>
24     form>
25 body>
26 html>

　　登录失败页面LoginError.jsp：

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>登录失败title>
 8 head>
 9 <body>
10     用户名或密码错误！
11 body>
12 html>

　　登录成功后的转账页面Transfer.jsp：

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>转账title>
 8 head>
 9 <body>
10     <form action="${pageContext.request.contextPath}/transfer" method="post">
11         <table>
12             <tr>
13                 <td align="center" colspan="2">欢迎你！${user.username}td>
14             tr>
15             <tr>
16                 <td align="right">用户名：td>
17                 <td><input type="text" name="username"/>td>
18             tr>
19             <tr>
20                 <td align="right">金额：td>
21                 <td><input type="text" name="sum"/>td>
22             tr>
23             <tr>
24                 <td/>
25                 <td align="right"><input type="submit" value="转账"/>td>
26             tr>
27         table>
28     form>
29 body>
30 html>

　　注册失败页面RegisterError.jsp：

 1 xml version="1.0" encoding="UTF-8" ?>
 2 DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 8 <title>注册失败title>
 9 head>
10 <body>
11     注册失败！
12 body>
13 html>

　　注册成功页面RegisterSuccess.jsp：

 1 xml version="1.0" encoding="UTF-8" ?>
 2 DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 7 <title>注册成功title>
 8 head>
 9 <body>
10     注册成功！
11 body>
12 html>

　　转账失败页面TransferError.jsp：

 1 xml version="1.0" encoding="UTF-8" ?>
 2 DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 8 <title>转账失败title>
 9 head>
10 <body>
11     转账失败！
12 body>
13 html>

　　转账成功页面TransferSuccess.jsp：

 1 xml version="1.0" encoding="UTF-8" ?>
 2 DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 8 <title>转账成功title>
 9 head>
10 <body>
11     转账成功！
12 body>
13 html>