Notes

主题

15.SSM（Spring、SpringMVC、MyBatis） ​

1.Maven ​

xml
<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.13</version>
        <scope>test</scope>
    </dependency>
    <!-- servlet -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>
    <!-- jsp -->
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.2</version>
    </dependency>
    <!-- jstl -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>
    <!-- spring-webmvc -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.2.4.RELEASE</version>
    </dependency>
    <!-- spring-jdbc -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>5.2.4.RELEASE</version>
    </dependency>
    <!-- spring-aop是基于aspect, 因此导入aspectjweaver -->
    <dependency>
        <groupId>org.apache.geronimo.bundles</groupId>
        <artifactId>aspectjweaver</artifactId>
        <version>1.6.8_2</version>
    </dependency>
    <!-- lombok -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.10</version>
    </dependency>
    <!-- mysql驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.46</version>
    </dependency>
    <!-- druid -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.4</version>
    </dependency>
    <!-- mybatis -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.3</version>
    </dependency>
    <!-- 日志 -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
    <!-- mybatis-spring, mybatis整合spring的jar包 -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis-spring</artifactId>
        <version>2.0.3</version>
    </dependency>
    <!-- MBG -->
    <dependency>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-core</artifactId>
        <version>1.4.0</version>
    </dependency>
</dependencies>

2.web.xml ​

xml
<?xml version="1.0" encoding="UTF-8"?>
<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_4_0.xsd"
         version="4.0">

    <!-- 1.启动Spring容器 -->
    <context-param>
        <!-- 配置Spring配置文件的位置 -->
        <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>

    <!-- 2.SpringMVC的前端控制器, 拦截所有请求 -->
    <servlet>
        <servlet-name>dispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <!-- 配置SpringMVC配置文件的位置 -->
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <!-- 设置启动级别 -->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <!-- 3.字符编码过滤器, 一定放在所有过滤器的前面 -->
    <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <!-- 设置字符集 -->
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <!-- 是否需要字符编码过滤器设置请求编码, 设置的字符集为encoding -->
            <param-name>forceRequestEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
        <init-param>
            <!-- 是否需要字符编码过滤器设置响应编码, 设置的字符集为encoding -->
            <param-name>forceResponseEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- 4.REST风格的URI -->
    <filter>
        <filter-name>hiddenHttpMethodFilter</filter-name>
        <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>hiddenHttpMethodFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

3.spring-mvc.xml ​

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:mvc="http://www.springframework.org/schema/mvc"
       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/mvc
       http://www.springframework.org/schema/mvc/spring-mvc.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">

    <!-- SpringMVC配置文件, 包含网站跳转逻辑的控制配置 -->
    <context:component-scan base-package="org.hong" use-default-filters="false">
        <!-- 只扫描控制器 -->
        <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>

    <!-- 配置视图解析器, 方便页面返回 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!-- 两个标准配置 -->
    <!-- 将SpringMVC不能处理的请求交给Tomcat -->
    <mvc:default-servlet-handler></mvc:default-servlet-handler>
    <!-- 能支持SpringMVC更高级的一些功能, JSR303校验, 快捷的ajax...映射动态请求 -->
    <mvc:annotation-driven></mvc:annotation-driven>

</beans>

4.dbconfig.properties ​

shell
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql:///ssm
jdbc.username=root
jdbc.password=1234

5.applicationContext.xml ​

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"
       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.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
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- Spring配置文件, 这里主要配置和业务逻辑有关的 -->
    <context:component-scan base-package="org.hong">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>

    <!-- 引入外部properties文件 -->
    <context:property-placeholder location="classpath:dbconfig.properties"></context:property-placeholder>
    <!-- 数据源 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <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>

    <!-- 配置MyBatis整合 -->
    <bean id="sessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 指定MyBatis全局配置文件的位置 -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!-- 指定数据源 -->
        <property name="dataSource" ref="dataSource"/>
        <!-- 指定MyBatis Mapper文件的位置 -->
        <property name="mapperLocations" value="classpath:org/hong/mapper"/>
    </bean>
    <!-- 配置扫描器, 将Mapper接口生成代理注入到Spring -->
    <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 指定mapper接口所在包 -->
        <property name="basePackage" value="org.hong.mapper"/>
        <!-- 指定sqlSessionFactoryBean配置在Spring中的id值 -->
        <property name="sqlSessionFactoryBeanName" value="sessionFactory"/>
    </bean>
    <!-- 配置一个专门用来进行Batch操作的sqlSession -->
    <bean id="sessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <!-- 指定sqlSessionFactory -->
        <constructor-arg name="sqlSessionFactory" ref="sessionFactory"/>
        <!-- 设置执行类型为Batch -->
        <constructor-arg name="executorType" value="BATCH"/>
    </bean>

    <!-- 事务控制 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!-- 控制主数据源 -->
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!-- 使用xml配置形式的事务(重要的都是使用xml) -->
    <aop:config>
        <!-- 配置切入点表达式 -->
        <aop:pointcut id="txPoint" expression="execution(* org.hong.service..*(..))"/>
        <!-- 配置事务增强 -->
        <aop:advisor advice-ref="txAdvice" pointcut-ref="txPoint"></aop:advisor>
    </aop:config>
    <!-- 配置事务增强, 事务如何切入; 并指定事务管理器, 事务管理器名称默认就是transactionManager -->
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <!-- 所有方法都是事务方法 -->
            <tx:method name="*"/>
            <!-- 以get开始的方法设置只读事务, 底层有优化 -->
            <tx:method name="get*" read-only="true"/>
        </tx:attributes>
    </tx:advice>

</beans>

6.log4j.properties ​

shell
log4j.rootLogger=DEBUG,A1

log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=[%t] [%c]-[%p] %m%n

7.mybatis-config.xml ​

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: 核心配置文件 -->
<configuration>
    <settings>
        <!-- 开启驼峰命名法 -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <!-- 日志 -->
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <!-- 批量起别名 -->
    <typeAliases>
        <package name="org.hong.pojo"/>
    </typeAliases>
</configuration>

8.项目结构 ​

9.测试 SSM ​

测试查询全部

9.1 SQL ​

shell
CREATE TABLE `tbl_dept` (
  `dept_id` INT(10) NOT NULL AUTO_INCREMENT,
  `dept_name` VARCHAR(30) DEFAULT NULL,
  PRIMARY KEY (`dept_id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
INSERT INTO tbl_dept(`dept_id`, `dept_name`) VALUES (1, '开发部');
INSERT INTO tbl_dept(`dept_id`, `dept_name`) VALUES (2, '测试部');

CREATE TABLE `tbl_employee` (
  `emp_id` INT(10) NOT NULL AUTO_INCREMENT,
  `emp_name` VARCHAR(30) DEFAULT NULL,
  `emp_gender` VARCHAR(30) DEFAULT NULL,
  `emp_email` VARCHAR(30) DEFAULT NULL,
  `d_id` INT(10) DEFAULT NULL,
  PRIMARY KEY (`emp_id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
INSERT INTO `tbl_employee`(`emp_id`, `emp_name`, `emp_gender`, `emp_email`, `d_id`) VALUES (1, 'Hong', '男', '190464706@qq.com', 1);
INSERT INTO `tbl_employee`(`emp_id`, `emp_name`, `emp_gender`, `emp_email`, `d_id`) VALUES (2, 'Tom', '男', 'Tom@qq.com', 2);
INSERT INTO `tbl_employee`(`emp_id`, `emp_name`, `emp_gender`, `emp_email`, `d_id`) VALUES (3, 'Jerry', '男', 'Jerry@qq.com', 1);
INSERT INTO `tbl_employee`(`emp_id`, `emp_name`, `emp_gender`, `emp_email`, `d_id`) VALUES (4, 'Bob', '男', 'Bob@qq.com', 1);
INSERT INTO `tbl_employee`(`emp_id`, `emp_name`, `emp_gender`, `emp_email`, `d_id`) VALUES (5, 'Lucy', '女', 'Lucy@qq.com', 2);
INSERT INTO `tbl_employee`(`emp_id`, `emp_name`, `emp_gender`, `emp_email`, `d_id`) VALUES (6, 'Jessica', '女', 'Jessica@qq.com', 2);

9.2 实体类 ​

java
package org.hong.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Dept {
    private Integer id;
    private String name;
}
java
package org.hong.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Employee {
    private Integer id;
    private String name;
    private String gender;
    private String email;
    private Dept dept;
}

9.3 Mapper 接口 ​

java
package org.hong.mapper;

public interface DeptMapper {
}
java
package org.hong.mapper;

import org.hong.pojo.Employee;

import java.util.List;

public interface EmployeeMapper {
    List<Employee> getAll();
}

9.4 Mapper.xml 文件 ​

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="org.hong.mapper.DeptMapper">
  <resultMap id="BaseResultMap" type="org.hong.pojo.Dept">
    <id column="dept_id" jdbcType="INTEGER" property="id" />
    <result column="dept_name" jdbcType="VARCHAR" property="name" />
  </resultMap>
</mapper>
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="org.hong.mapper.EmployeeMapper">
  <resultMap id="BaseResultMap" type="org.hong.pojo.Employee">
    <id column="emp_id" jdbcType="INTEGER" property="id" />
    <result column="emp_name" jdbcType="VARCHAR" property="name" />
    <result column="emp_gender" jdbcType="CHAR" property="gender" />
    <result column="emp_email" jdbcType="VARCHAR" property="email" />
  </resultMap>
  <resultMap id="EmployeeJoin" type="Employee" extends="BaseResultMap">
    <association property="dept" resultMap="org.hong.mapper.DeptMapper.BaseResultMap"></association>
  </resultMap>

  <sql id="JoinColumn">
    emp_id, emp_name, emp_gender, emp_email, dept_id, dept_name
  </sql>

  <select id="getAll" resultMap="EmployeeJoin">
    select <include refid="JoinColumn"/> from tbl_employee left join tbl_dept on d_id = dept_id
  </select>
</mapper>

9.5 service 接口 ​

java
package org.hong.service;

import org.hong.pojo.Employee;

import java.util.List;

public interface EmployeeService {
    List<Employee> getAll();
}

9.6 serviceimpl 实现类 ​

java
package org.hong.service.serviceimpl;

import org.hong.mapper.EmployeeMapper;
import org.hong.pojo.Employee;
import org.hong.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class EmployeeServiceImpl implements EmployeeService {
    @Autowired
    private EmployeeMapper employeeMapper;

    @Override
    public List<Employee> getAll() {
        // 使用 MyBatis-Spring 之后，你不再需要直接使用 SqlSessionFactory 了，
        // 因为你的 bean 可以被注入一个线程安全的 SqlSession，
        // 它能基于 Spring 的事务配置来自动提交、回滚、关闭 session。
        return employeeMapper.getAll();
    }
}

9.7 EmployeeController ​

java
package org.hong.controller;

import org.hong.pojo.Employee;
import org.hong.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

import java.util.List;

@Controller
public class EmployeeController {
    @Autowired
    private EmployeeService employeeService;

    @GetMapping("/employee")
    public String getAll(Model model){
        List<Employee> employees = employeeService.getAll();
        model.addAttribute("employees", employees);
        return "list";
    }
}

整合完毕！！！

9.8 list.jsp ​

html
<%-- Created by IntelliJ IDEA. User: 谢禹宏 Date: 2021-04-22 Time: 10:37 To change this template use File | Settings |
File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib prefix="c"
uri="http://java.sun.com/jsp/jstl/core" %>
<html>
  <head>
    <title>Title</title>
  </head>
  <body>
    <table align="center">
      <tr>
        <th>ID</th>
        <th>Name</th>
        <th>Gender</th>
        <th>Email</th>
        <th>DeptName</th>
      </tr>
      <c:forEach items="${requestScope.employees}" var="employee">
        <tr>
          <td>${employee.id}</td>
          <td>${employee.name}</td>
          <td>${employee.gender}</td>
          <td>${employee.email}</td>
          <td>${employee.dept.name}</td>
        </tr>
      </c:forEach>
    </table>
  </body>
</html>

9.9 访问 /employee ​

控制台打印

bash
## MyBatis-Spring帮我们创建了sqlSession对象
[http-nio-8080-exec-6] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Creating a new SqlSession
## 并且注册了一个transaction事务到sqlSession对象中
[http-nio-8080-exec-6] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Registering transaction synchronization for SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3a361206]
## JDBC Connection交给Spring管理
[http-nio-8080-exec-6] [org.mybatis.spring.transaction.SpringManagedTransaction]-[DEBUG] JDBC Connection [com.mysql.jdbc.JDBC4Connection@3fe4f94] will be managed by Spring
## MyBatis发送sql
[http-nio-8080-exec-6] [org.hong.mapper.EmployeeMapper.getAll]-[DEBUG] ==>  Preparing: select emp_id, emp_name, emp_gender, emp_email, dept_id, dept_name from tbl_employee left join tbl_dept on d_id = dept_id
[http-nio-8080-exec-6] [org.hong.mapper.EmployeeMapper.getAll]-[DEBUG] ==> Parameters:
[http-nio-8080-exec-6] [org.hong.mapper.EmployeeMapper.getAll]-[DEBUG] <==      Total: 2
## 进入事务和sqlSession释放环节
[http-nio-8080-exec-6] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3a361206]
## 提交事务
[http-nio-8080-exec-6] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization committing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3a361206]
## 注销事务
[http-nio-8080-exec-6] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3a361206]
## 关闭sqlSession
[http-nio-8080-exec-6] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3a361206]

10.SqlSessionTemplate ​

SqlSessionTemplate 是 MyBatis-Spring 的核心。作为**SqlSession**的一个实现，这意味着可以使用它无缝代替你代码中已经在使用的 SqlSession。 **SqlSessionTemplate**是线程安全的，可以被多个 DAO 或映射器所共享使用。

当调用 SQL 方法时（包括由 getMapper() 方法返回的映射器中的方法），**SqlSessionTemplate**将会保证使用的**SqlSession****与当前 Spring 的事务相关。 此外，它管理 session 的生命周期，包含必要的关闭、提交或回滚操作。**另外，它也负责将 MyBatis 的异常翻译成 Spring 中的 DataAccessExceptions。

由于模板可以参与到 Spring 的事务管理中，并且由于其是线程安全的，可以供多个映射器类使用，你应该总是用 SqlSessionTemplate 来替换 MyBatis 默认的 DefaultSqlSession 实现。在同一应用程序中的不同类之间混杂使用可能会引起数据一致性的问题。

可以使用 SqlSessionFactory 作为构造方法的参数来创建 SqlSessionTemplate 对象。

总结

  • SqlSessionTemplate 是 SqlSession 接口的一个实现类。SqlSessionTemplate 就是 SqlSession，并且是线程安全的。
  • SqlSessionTemplate 会管理 seesion 的生命周期，包括事务的提交或回滚和 session 的关闭。我们使用时不需要关注 sqlSession 的创建、关闭和事务提交或回滚。

Released under the MIT License.

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