Maven+SSM project

Maven+SSM project

table of Contents

1. Create a project

Create a Maven project and click Next.

2. Import dependent packages

3. Modify the web.xml configuration file

4. Configure Spring configuration file related content

4.1.applicationContext-dao.xml

4.2.applicationContext-service.xml

5. Place spring MVC.xml

6. Verification

6.1. Create data in the database

 6.2. Create entity objects

6.3. Create Mapper and corresponding mapping

6.4. Create Service and corresponding ServeImpl

6.5. Controller creation

 6.6. Verification test

---

1. Create a project

Create a Maven project and click Next.

Fill in the GroupId and Artifactld, and click Next.

Maven needs to wait for the java and resources folders to be loaded before proceeding with development. If not, click a few more times

Right-click the project -> Maven -> Reimport.

If it still doesn't work, add something to pom.xml and then comment it out.

2. Import dependent packages

<?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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>edu.wan</groupId>
  <artifactId>MavenSSH</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>MavenSSH Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>
    <!--测试包 -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <!--*****************************mybatis部分********************************-->
    <!--mybatis-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.2</version>
    </dependency>
    <!--mybatis-spring-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.2</version>
    </dependency>
    <!--*****************************mybatis部分********************************-->

    <!--*****************************数据库驱动部分********************************-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.45</version>
    </dependency>
    <!--*****************************数据库驱动部分********************************-->

    <!--*****************************连接池********************************-->
    <dependency>
      <groupId>com.mchange</groupId>
      <artifactId>c3p0</artifactId>
      <version>0.9.5.4</version>
    </dependency>
    <!--*****************************连接池********************************-->

    <!--*****************************日志********************************-->
<!--    <dependency>-->
<!--      <groupId>log4j</groupId>-->
<!--      <artifactId>log4j</artifactId>-->
<!--      <version>1.2.11</version>-->
<!--    </dependency>-->
    <!-- slf4j日志包-->
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>1.7.21</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>1.7.21</version>
    </dependency>
    <!-- 引入log4j日志包-->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.16</version>
    </dependency>
    <!--*****************************日志********************************-->

    <!--*****************************jackson********************************-->
<!--    <dependency>-->
<!--      <groupId>org.codehaus.jackson</groupId>-->
<!--      <artifactId>jackson-mapper-asl</artifactId>-->
<!--      <version>1.9.9</version>-->
<!--    </dependency>-->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.9.10</version>
    </dependency>
    <!-- 这里解决的问题是springMVC不能直接把对象转换成json 不过不进行特殊处理的话就会抛出
     HttpMessageNotWritableException: No converter found for return value of type
     也许要在springMVC中进行配置。
    -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.9.10</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.9.10</version>
    </dependency>
    <!--*****************************jackson********************************-->
    <!--*****************************jsp-api********************************-->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.0</version>
      <scope>provided</scope>
    </dependency>
    <!--*****************************jsp-api********************************-->

    <!--*****************************jstl********************************-->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
    <!--*****************************jstl********************************-->

    <!--*****************************cglib********************************-->
    <dependency>
      <groupId>cglib</groupId>
      <artifactId>cglib</artifactId>
      <version>3.3.0</version>
    </dependency>
    <!--*****************************cglib********************************-->

    <!--*****************************aspectj********************************-->
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjrt</artifactId>
      <version>1.9.4</version>
    </dependency>
    <!--*****************************aspectj********************************-->

      <!--*****************************spring部分********************************-->
      <!--spring-core-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-core</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-context-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-context-support-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context-support</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>

      <!--spring-tx-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-tx</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-orm-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-orm</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-oxm-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-oxm</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>

      <!--spring-web-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-web</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-test-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-test</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-webmvc-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-webmvc</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--spring-aspects-->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-aspects</artifactId>
          <version>5.1.2.RELEASE</version>
      </dependency>
      <!--aop联盟-->
      <dependency>
          <groupId>aopalliance</groupId>
          <artifactId>aopalliance</artifactId>
          <version>1.0</version>
      </dependency>
      <!--*****************************spring部分********************************-->

  </dependencies>

  <build>
    <finalName>MavenSSH</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- 设置原文件编码方式-->
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <configuration>
            <source>1.8</source>
            <target>1.8</target>
            <encoding>utf-8</encoding>
          </configuration>
        </plugin>
        <plugin>
          <groupId>org.apache.tomcat.maven</groupId>
          <artifactId>tomcat7-maven-plugin</artifactId>
          <version>2.2.0</version>
          <configuration>
            <port>8080</port>
            <path>/</path>
            <uriEncoding>UTF-8</uriEncoding>
            <server>tomcat7</server>
          </configuration>
        </plugin>
      </plugins>
    </pluginManagement>
    <resources>
      <resource>
        <directory>src/main/java</directory>
        <includes>
          <include>**/*.properties</include>
          <include>**/*.xml</include>
        </includes>
        <filtering>true</filtering>
      </resource>
      <resource>
        <directory>src/main/resources</directory>
        <includes>
          <include>**/*.properties</include>
          <include>**/*.xml</include>
        </includes>
        <!--如果这里是true的化就可以指定的替换里面的内容
        https://blog.csdn.net/qq_34561892/article/details/85277265?utm_medium=distribute.pc_aggpage_search_result.none-task-blog-2~aggregatepage~first_rank_v2~rank_aggregation-1-85277265.pc_agg_rank_aggregation&utm_term=filtering+%E6%A0%87%E7%AD%BE&spm=1000.2123.3001.4430
         -->
        <filtering>true</filtering>
      </resource>
    </resources>
  </build>
</project>

Note: The reference for the injection of dependent packages is (some minor changes have been made, and the changes may not be good)

https://blog.csdn.net/weixin_42341232/article/details/100127168

3. Modify the web.xml configuration file

<!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>
  <!--加载spring配置文件，使用通配符方式
  在服务启动的时候去加载param-value中指定的配置文件
  -->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:spring/applicationContext-*.xml</param-value>
  </context-param>
  
  <context-param>
    <param-name>log4jConfigLocation</param-name>
    <param-value>classpath:log4j.properties</param-value>
  </context-param>

  <!--解决post提交乱码问题 -->
  <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>

  <!--ContextLoaderListener
    在启动Web容器时,读取contextConfigLocation配置的xml文件,自动装配ApplicationContext的配置信息
    并产生WebApplicationContext对象，并将这个对象放入ServletContext属性中，这样我们就可以通过Servlet就可以获取到
    WebApplicationContext对象。

    //下面的代码就是从当前的Servlet类中获取上层的ServletContext
    ServletContext servletContext = this.getServletContext();

    servletContext说白了就是所有的Servlet的上层
  -->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <!--log4j配置监听-->
<!--  <listener>-->
<!--    <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>-->
<!--  </listener>-->

  <!--配置springMVC前端控制器
      所有的请求都先请求到前端控制器,然后前端控制器判断调用那个Handle,通过获得的处理执行链
      去处理适配器进行处理返回ModeAndView,之后调用视图解析器返回View之后就是进行视图的渲染。
   -->
  <servlet>
    <servlet-name>springMVC</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--init-param给DispatcherServlet设置参数,并且把数据放入到WebApplicationContext对象-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath*:spring/springMVC.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>springMVC</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!--异常页面，当没有发现的时候，会根基这个404代码返回相对应的jsp页面 -->
  <error-page>
    <error-code>404</error-code>
    <location>/WEB-INF/jsp/error/404.jsp</location>
  </error-page>
</web-app>

4. Configure Spring configuration file related content

I divided the Spring configuration file into two parts

4.1.applicationContext-dao.xml

When configuring applicationContext-dao, you need to configure the db.properties information and the corresponding configuration file of SqlMapConfig.xml.

First configure db.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/mybatis
jdbc.username=root
jdbc.password=123456

Then configure SqlMapConfig.xml (there is no configuration information, I commented out the introduction)

<?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>
    <!--classpath 指的就是达成war包之后classes的路径 -->
    <!--引入外部的配置文件 -->
<!--    <properties resource="classpath:db.properties"/>-->

    <!--environments 只是引入mybtis的时候使用 environments 进行数据源的配置 -->
<!--    <environments default="mysql">-->
<!--        &lt;!&ndash; 配置mysql的环境&ndash;&gt;-->
<!--        <environment id="mysql">-->
<!--            &lt;!&ndash; 配置事务 &ndash;&gt;-->
<!--            <transactionManager type="JDBC"/>-->
<!--            &lt;!&ndash;配置连接池&ndash;&gt;-->
<!--            <dataSource type="POOLED">-->
<!--               <property name="driver" value="${driver}"></property>-->
<!--               <property name="url" value="${url}"></property>-->
<!--               <property name="username" value="${username}"></property>-->
<!--               <property name="password" value="${password}"></property>-->
<!--            </dataSource>-->
<!--        </environment>-->
<!--    </environments>-->

    <!--引入Mapper的配置文件-->
<!--    <mappers>-->
<!--        <mapper resource="mybatis/mapper/user/UserMapper.xml"></mapper> &lt;!&ndash;使用mapper映射出来 &ndash;&gt;-->
<!--    </mappers>-->
</configuration>

Configure applicationContext-dao.xml information

<?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">

    <!--导入配置文件 -->
    <context:property-placeholder location="classpath:db.properties"/>

    <!--创建数据连接池
     理解：在单独使用mybtis的时候，我们至于要配置 <environments> 标签即可，mybatis在进行文件解析的时候
     会解析到sqlSession中，稍后我们会把这个datasource放入到mybatis的sqlsession中，这样sqlsesson就无须在创建
     datasource了
     -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

    <!--配置mybatis的sqlSessionFactory属性-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--给sqlSessionFactory配置dataSource数据源-->
        <property name="dataSource"  ref="dataSource"/>
        <!--为Mybatis引入外部的配置文件-->
        <!--如果需要进行特殊的配置引入在SqlMapConfig.xml中进行配置-->
        <!--<property name="configLocation" value="classpath:mybatis/SqlMapConfig.xml"/>-->
        <!--
            配置Mapper的方法
            1）.在上面的configLocation不是配置了加载mybatis的SqlMapConfig.xml,配合的路径可以写在里面
            2）.在sqlSessionFactory中配置了mapperLocations，同时指定mapper的配置路径，也可以进行Mapper的注入
        -->
        <property name="mapperLocations" value="classpath*:mybatis/mapper/*/*.xml"/>
    </bean>

    <!--启动Mapper扫描器 -->
    <!--Mapper的动态道理交给的spring进行管理,可以直接从spring中直接获取Mapper的对象 -->
    <!--扫描Mapper的接口,生成代理对象,生成的代理对象会在IOC的容器中-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!--按照包进行扫描 -->
        <property name="basePackage" value="edu.wan.mapper"/>
        <!--加载上面的sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    </bean>
</beans>

4.2.applicationContext-service.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:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop"
       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
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--启动包扫描
        spring定义Service bean有两种方式
        1).通过包扫描的方式
        2).第二种就是直接注入的形式
    -->
    <context:component-scan base-package="edu.wan"/>
<!--    <bean id="userService" class="edu.wan.serviceImpl.UserServiceImpl"/>-->

    <!--配置事务管理器 -->
    <!--管理配置有两种配置方法
        1）.在transactionManager的配置执行新增首先在<beans>标签上增加 xmlns以及 xsi:schemaLocation 然后后面的配置如下
        2）.
    -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
        <!--事务管理的注解驱动 -->
        <!--<tx:annotation-driven transaction-manager="transactionManager"/>-->
    </bean>

    <!--
        配合spring的事务
        首先需要介绍下 propagation 可以配置参数的含义
        PROPAGATION_REQUIRED :
            Spring默认的传播机制  如果外层有事务，则当前事务加入到外层事务，一块提交，一块回滚。如果外层没有事务，新建一个事务执行
        PROPAGATION_REQUES_NEW :
            该事务传播机制是每次都会新开启一个事务，同时把外层事务挂起，当当前事务执行完毕，恢复上层事务的执行。
            如果外层没有事务，执行当前新开启的事务即可
       PROPAGATION_SUPPORT
            如果外层有事务，则加入外层事务，如果外层没有事务，则直接使用非事务方式执行。完全依赖外层的事务
       PROPAGATION_NOT_SUPPORT
            该传播机制不支持事务，如果外层存在事务则挂起，执行完当前代码，则恢复外层事务，无论是否异常都不会回滚当前的代码
       PROPAGATION_NEVER
            该传播机制不支持外层事务，即如果外层有事务就抛出异常
       PROPAGATION_MANDATORY
            与NEVER相反，如果外层没有事务，则抛出异常
       PROPAGATION_NESTED (...)
            该传播机制的特点是可以保存状态保存点，当前事务回滚到某一个点，
            从而避免所有的嵌套事务都回滚，即各自回滚各自的，如果子事务没有把异常吃掉，基本还是会引起全部回滚的
    -->
    <tx:advice id="transactionAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="query*" propagation="SUPPORTS" read-only="true"/>
            <tx:method name="find*" propagation="SUPPORTS" read-only="true"/>
            <tx:method name="get*" propagation="SUPPORTS" read-only="true"/>
            <tx:method name="save*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="insert*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="update*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="modify*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="delete*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="remove*" propagation="REQUIRED" read-only="false"/>
        </tx:attributes>
    </tx:advice>

    <!--配置Aop 该事务处理功能只对ServiceImpl生效 -->
    <!--
        我印象中定义切面使用的是<aop:aspect> 但是为什么这里使用的是<aop:advisor>
        百度查询发现<aop:aspect> 在普通的bean中就能够定义
        但是<aop:advisor>的定义必须实现advice接口
    -->
    <aop:config>
        <aop:advisor advice-ref="transactionAdvice" pointcut="execution(* edu.wan.serviceImpl.*.*(..))"/>
    </aop:config>
</beans>

5. Place spring MVC.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: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">

    <!--
       扫描controller包，获取所有的controller层
    -->
    <context:component-scan base-package="edu.wan.controller"/>

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

    <!--解决返回对象前端不识别的问题，这里直接转换层jspn-->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
        </mvc:message-converters>
    </mvc:annotation-driven>
</beans>

6. Verification

6.1. Create data in the database

-- ----------------------------
-- Table structure for `users`
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `uid` int(11) NOT NULL AUTO_INCREMENT,
  `uname` varchar(20) NOT NULL,
  `uage` int(11) NOT NULL,
  PRIMARY KEY (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of users
-- ----------------------------
INSERT INTO `users` VALUES ('1', '张三', '20');
INSERT INTO `users` VALUES ('2', '李四', '18');

 6.2. Create entity objects

package edu.wan.po;
import java.io.Serializable;

public class User implements Serializable {

    private String uid;

    private String uname;

    private String uage;

   //省略get set方法以及对应的toString方法
}

6.3. Create Mapper and corresponding mapping

Create Mapper interface

package edu.wan.mapper;
import edu.wan.po.User;

public interface UserMapper {
    public User findById(int id);
}

 Create 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为映射的根节点，namespace指定Dao接口的完整类名
 mybatis会依据这个接口动态创建一个实现类去实现这个接口，
  而这个实现类是一个Mapper对象-->

<!--正常的情况下这里直接配置Mapper的接口类 -->
<mapper namespace="edu.wan.mapper.UserMapper">

    <!--定义返回的Map，这样的画就可能对实体类进行更加具体的细分
        1.和前端交互的内容 VO
        2.和数据库交互的数据DTO
        3.返回的数据类型
     -->
    <!--
        通过定义resultMap，还有子啊多变联查的时候，也需要使用这个进行处理
        collection 标签进行数据的关联 （一对多的情况下）
        association 标签进行数据的关联（一对一的情况下）
    -->
    <resultMap id="UserPojo" type="edu.wan.po.User">
        <result column="uid" property="uid"></result>
        <result column="uname" property="uname"></result>
        <result column="uage" property="uage"></result>
        <!--        <collection property="xxxList" ofType="com.xx.xx">-->
        <!--            &lt;!&ndash;在这里建立联系&ndash;&gt;-->
        <!--            <result column="id" property="uid"></result>-->
        <!--            <result column="ordertime" property="ordertime"></result>-->
        <!--            <result column="total" property="total"></result>-->
        <!--        </collection>-->

        <!--        <association property="xxxxpojo" javaType="com.xx.xxx">-->
        <!--            <result column="id" property="uid"></result>-->
        <!--            <result column="username" property="username"></result>-->
        <!--            <result column="password" property="password"></result>-->
        <!--            <result column="birthday" property="birthday"></result>-->
        <!--        </association>-->
    </resultMap>

    <!-- id ="接口中的方法名"  parameterType="传入的参数类型"　resultType = "返回实体类对象，使用包.类名"-->
    <!-- 如果当前返回的是一个对象的化，就直接使用resultType返回对象名称
         如果挡墙返回的是一个通过resultMap定义好的Map类型 需要使用resultMap
     -->
    <!--    <select id="findById" parameterType="int" resultType="edu.wan.pojo.User">-->
    <select id="findById" parameterType="int" resultMap="UserPojo">
            select * from users where uid = #{id}
        </select>
</mapper>

6.4. Create Service and corresponding ServeImpl

Service interface class creation

package edu.wan.service;
import edu.wan.po.User;

public interface UserService {
    public User findById(int id);
}

ServiceImpl interface creation

package edu.wan.serviceImpl;

import edu.wan.mapper.UserMapper;
import edu.wan.po.User;
import edu.wan.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 findById(int id) {
        User user = userMapper.findById(id);
        return user;
    }
}

6.5. Controller creation

package edu.wan.controller;

import edu.wan.po.User;
import edu.wan.service.UserService;
import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
    跨域请求的详解
    场景1：假设该服务部署的8080端口，我需要调用8081的服务的方法，如果我直接调用的话
    http://127.0.0.1:8080 -> http://127.0.0.1:8081 以为只要是
    请求的协议（http或者https）、ip、端口 任意一个改变都属于跨域的请求
    这是由Netscape 公司提出的安全策略

    如果我把调用的8081提供服务的方法或者controlle配置上@CrossOrigin就可以进行跨域的调用了
 */
@CrossOrigin //解决请求跨域的问题
@Controller
@RequestMapping("/user")
public class UserController {

    Logger log = Logger.getLogger(UserController.class);

    @Autowired
    private UserService userService;

    @RequestMapping("/query")
    public @ResponseBody User findUserById(){
        int id = 1;
        return userService.findById(id);
    }

 6.6. Verification test

At this point, a simple SSM project has been built.

Download the project: https://gitee.com/Wanbogo/csdnblogs.git  in MavenSSH

Note: Some basic things of the architecture will be added later, such as: unified exception handling, log handling, and some corresponding tools.