基于ssm框架如何连接数据库

基于SSM框架如何连接数据库

使用SSM框架连接数据库的核心步骤包括：配置数据库连接、配置MyBatis、配置Spring、实现数据访问层。 在本文中，我们将详细探讨每一步骤，并提供示例代码和配置文件，以确保您能够顺利完成SSM框架与数据库的连接。

一、配置数据库连接

1. 添加数据库驱动依赖

在项目的pom.xml文件中，添加数据库驱动的依赖项。例如，如果使用MySQL数据库，添加以下依赖：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.23</version>
</dependency>

2. 配置数据库连接信息

创建一个数据库配置文件（如db.properties），并在其中添加数据库连接信息：

jdbc.driverClassName=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/yourDatabaseName?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
jdbc.username=yourUsername
jdbc.password=yourPassword

二、配置MyBatis

1. MyBatis配置文件

创建MyBatis配置文件mybatis-config.xml，用于指定MyBatis的基本配置：

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driverClassName}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
    </mappers>
</configuration>

2. Mapper映射文件

创建Mapper映射文件（如UserMapper.xml），用于定义SQL语句：

<?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.example.mapper.UserMapper">
    <select id="getUserById" parameterType="int" resultType="com.example.model.User">
        SELECT * FROM users WHERE id = #{id}
    </select>
</mapper>

三、配置Spring

1. Spring配置文件

创建Spring配置文件（如applicationContext.xml），并在其中配置数据源、事务管理器和MyBatis-Spring集成：

<?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"
       xmlns:tx="http://www.springframework.org/schema/tx"
       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/tx
           http://www.springframework.org/schema/tx/spring-tx.xsd">
    <!-- 数据源配置 -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    <!-- MyBatis SqlSessionFactory配置 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>
    <!-- MyBatis Mapper扫描配置 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.example.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    </bean>
    <!-- 事务管理器配置 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

四、实现数据访问层

1. 创建Mapper接口

在项目中创建Mapper接口（如UserMapper.java），并定义数据访问方法：

package com.example.mapper;
import com.example.model.User;
import org.apache.ibatis.annotations.Select;
public interface UserMapper {
    @Select("SELECT * FROM users WHERE id = #{id}")
    User getUserById(int id);
}

2. 创建Service层

创建Service层接口和实现类，负责业务逻辑处理：

package com.example.service;
import com.example.model.User;
public interface UserService {
    User getUserById(int id);
}
package com.example.service.impl;
import com.example.mapper.UserMapper;
import com.example.model.User;
import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    @Override
    public User getUserById(int id) {
        return userMapper.getUserById(id);
    }
}

五、配置Spring MVC

1. Spring MVC配置文件

创建Spring MVC配置文件（如spring-mvc.xml），并配置Spring MVC相关信息：

<?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"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       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/mvc
           http://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <context:component-scan base-package="com.example"/>
    <mvc:annotation-driven/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

2. 创建Controller

创建Controller类，处理客户端请求并调用Service层：

package com.example.controller;
import com.example.model.User;
import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    @RequestMapping(value = "/getUserById", method = RequestMethod.GET)
    public String getUserById(@RequestParam("id") int id, Model model) {
        User user = userService.getUserById(id);
        model.addAttribute("user", user);
        return "userDetail";
    }
}

六、测试与运行

1. 配置web.xml

在web.xml中配置Spring MVC前端控制器：

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                             http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <servlet>
        <servlet-name>springDispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springDispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

2. 创建视图页面

创建视图页面（如userDetail.jsp），用于展示用户信息：

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
    <title>User Detail</title>
</head>
<body>
    <h1>User Detail</h1>
    <p>ID: ${user.id}</p>
    <p>Name: ${user.name}</p>
    <p>Email: ${user.email}</p>
</body>
</html>

通过上述步骤，您已经成功配置了基于SSM框架与数据库的连接，并实现了基本的数据访问和展示功能。确保各个配置文件和代码的正确性是关键，这样才能确保项目的顺利运行。