基于IDEA和Maven的SSM分层项目搭建

前言

虽然现在SpringBoot开始流行，但是SSM作为一个经典框架，还是有必要去了解一下。

项目建立

1.新建一个空白的Maven项目,如下图。然后把IDEA自动生成的多余src目录删掉。

2.右键项目新建Module,选择Module类型,ArtfactId为Web,如下

、

3.继续新建空白Module,分别建立api,biz,common,repository,sal模块，这样基本的项目就建立起来了.

4.接下来再如下图配置一下Tomcat服务器,就可以运行项目,在程序上看到  "Hello World!"

SpringMVC

现在主流都是前后端分离,所以control层都是以restful的形式返回json格式数据,下面写了个查询部门类别的例子,需要建立多个文件,如下图

文件从上往下分别为

public class DeptInfo {

    private Integer id;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }
}

DeptInfo.java

@Service
public class DeptServiceImpl implements DeptService {

    @Override
    public List<DeptInfo> listDeptInfo(String name) {
        List<DeptInfo> deptInfos=new ArrayList<>();
        for (int i=0;i<2;i++)
        {
            DeptInfo info=new DeptInfo();
            info.setName("部门"+i);
            info.setId(i);
            deptInfos.add(info);
        }
        return deptInfos;
    }
}

DeptServiceImpl.xml

public interface DeptService {
    List<DeptInfo> listDeptInfo(String name);
}

DeptService.java

@RestController
@RequestMapping(value = "/dept")
public class DeptController {

    @Autowired
    private DeptService deptService;

    @RequestMapping(value = "/get", method = RequestMethod.GET)
    public String getDept(String id) {
          return "部门id"+id;
    }

    @RequestMapping(value = "/getList", method = RequestMethod.GET)
    public List<DeptInfo> getDeptList(String name) {
        return deptService.listDeptInfo(name);
    }
}

DeptController.java

<?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:tx="http://www.springframework.org/schema/tx"
       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/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">

    <context:component-scan base-package="cn.com.test">
    </context:component-scan>
</beans>

applicationContext.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/aop     http://www.springframework.org/schema/aop/spring-aop-4.0.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
           http://www.springframework.org/schema/mvc     http://www.springframework.org/schema/mvc/spring-mvc.xsd
       ">
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean id="stringConverter"  class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/html;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
            <bean id="jsonConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>application/json;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    <context:component-scan base-package="cn.com.test.springmvc.web"/>
</beans>

dispatcher-servlet.xml

<!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>
  <display-name>Archetype Created Web Application</display-name>
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/applicationContext.xml</param-value>
  </context-param>

  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <servlet>
    <servlet-name>dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

web.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/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springmvc</artifactId>
        <groupId>cn.com.test.springmvc</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>web</artifactId>
    <packaging>war</packaging>
    <name>web Maven Webapp</name>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.0.7.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.1</version>
        </dependency>
        <dependency>
            <groupId>cn.com.test.springmvc</groupId>
            <artifactId>biz</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
    <build>
        <finalName>web</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>
            </plugins>
        </pluginManagement>
    </build>
</project>

pom.xml

运行后可以看到如下

[{"id":0,"name":"部门0"},{"id":1,"name":"部门1"}]

Mybaits

接下来接入Mybaits数据库操作,需要改以下文件

@Service
public class DeptServiceImpl implements DeptService {
    @Autowired
    DeptDOMapper deptDOMapper;
    @Override
    public List<DeptInfo> listDeptInfo(String name) {
        List<DeptDO> deptDOList=  deptDOMapper.listDept(name);
        List<DeptInfo> deptInfos=new ArrayList<>();
        deptDOList.stream().forEach(x->{
            DeptInfo info=new DeptInfo();
            info.setName(x.getName());
            info.setId(x.getId());
            deptInfos.add(info);
        });
        return deptInfos;
    }
}

DeptServiceImpl.java

public class DeptDO {
    private Integer id;

    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

DeptDO.java

@Repository
public interface DeptDOMapper {
    List<DeptDO> listDept(@Param("name")String name);
}

DeptDOMapper.java

<?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="cn.com.test.springmvc.repository.mapper.DeptDOMapper" >
    <resultMap id="BaseResultMap" type="cn.com.test.springmvc.repository.entity.DeptDO" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="name" property="name" jdbcType="VARCHAR" />
    </resultMap>

    <select id="listDept" resultMap="BaseResultMap" >
        select id,name from test_dept
        <where>
            <if test="name !=null and name !=''">
                and name like  concat('%',#{name},'%')
            </if>
        </where>
    </select>
</mapper>

DeptDOMapper.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:tx="http://www.springframework.org/schema/tx"
       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/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">

    <context:component-scan base-package="cn.com.test">
    </context:component-scan>
    <bean  id="dataSource"  class="org.springframework.jdbc.datasource.SimpleDriverDataSource">
        <property name="username" value="root"></property>
        <property name="password" value="111111"></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/mysql"></property>
    </bean>

    <bean id="SqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="mapperLocations" value="classpath*:*Mapper.xml"/>
    </bean>

    <bean id="dataScanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.com.test.springmvc.repository.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="SqlSessionFactory"/>
    </bean>

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

applicationContext.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/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springmvc</artifactId>
        <groupId>cn.com.test.springmvc</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>web</artifactId>
    <packaging>war</packaging>
    <name>web Maven Webapp</name>
    <url>http://www.example.com</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.0.7.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.1</version>
        </dependency>
        <dependency>
            <groupId>cn.com.test.springmvc</groupId>
            <artifactId>biz</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>web</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>
            </plugins>
        </pluginManagement>
    </build>
</project>

pom.xml

运行后,可以得到来自我数据库的测试数据

[{"id":1,"name":"test1"},{"id":2,"name":"我的部门"}]

补充说明

从上面项目结构看到,这个SSM应用分成了几个模块,如下

api	一个大型系统肯定是不止一个应用的,而应用间通常会有数据交互,而数据交互需要应用对外的接口,而api模块的职责就是提供对外接口,通常以jar包的形式发放出去
biz	业务逻辑代码就是写在这里,应用内部的核心,依赖api,common,repository,sal
common	存放帮助类,aop类,异常类等
repository	存储层,对数据库的操作都体现在这里
sal	和api职责相反,主要是调用外部系统的服务
web	control层,给前端提供restful接口

分层的影响其实也是有好有坏,对于复杂的业务来说,分层可以使逻辑清晰,职责分明,如果以后重构代码也能控制好边界,降低风险。再极端一点的例子，如果数据库要从Mysql换到Oracle，可能只需要改repository层的一点点代码和配置信息。

坏处也有的，如果是简单的增删改查业务，也要在各层定义模型，层层透传，相当费劲。

小结

上文演示了如何从零构建一个SSM项目，当然这只是一个最基础功能，后面还会加入日志，aop，异常处理，应用间调用等功能。