教你如何使用IDEA + Maven 搭建SSM Web项目(超详细)

前言

本文将带你一步一步使用IDEA搭建SSM项目(Spring SpringMVC Mybatis)。最终所实现的效果是通过访问用户注册界面(http://localhost/register.jsp)，将新用户添加进MySQL数据库。通过post方法访问http://localhost/emp/getAll,获取所有用户信息的json数据。

1. 环境

java version:12.0.2
maven版本:3.6.1
MySQL版本:5.x

2. 前期准备

创建数据库:

CREATE DATABASE mybatisdb;

创建表:

create table employee(
  eid int(5) primary key,
  ename varchar(20),
  esalary double(8,2),
  esex varchar(2)
);

3. 开始创建工程

1.File->New->Project…

2.选择Maven项目

3.填写项目信息

3.设置Maven

我在这里选择的是我自己下载的一个maven，maven的源已经被我在settings.xml中设置成了阿里的源，如果不设置的将会导致下载jar包时消耗很长的时间。设置方法就不在这里讲了，网上教程一大堆。

4.选择项目存放路径，最后点Finish

此时的项目结构如下:

4. 调整IDEA自动创建的工程目录

4.1 创建源代码路径

右键main文件夹---->new—>Directory,取名为java

将该目录设置为源代码路径

创建包com.yky,并在包中创建domain、dao、service、controller。创建好的包目录如下:

4.2 创建test路径

右键src—>new—>Directory,取名为test。在新创建的test目录下创建java文件夹，并设置为test的根目录

在test/java目录下创建com.yky.dao包，用于存放dao层的测试代码

4.3 创建resource路径

创建resource路径专门用来存放配置文件
右键main文件夹—>new->Directory,取名为resource。并设置为resource根路径

为了让配置文件看起来不乱，在resource目录下创建mapper目录，专门用来存放Mybatis的mappper文件。

在WEB-INF下创建jsp目录，用来专门存放jsp。

4.4 整个的目录结构

至此，目录就创建完成了。完整的目录结构如下:

4.5 修改pom.xml文件

想要使用Spring 、SpringMVC、Mybatis，我们需要用Maven导入相关的jar包。配置pom.xml文件如下:
注意这里的jdk版本设置成了12，如果使用的jdk版本与我的不同，请做出相应的更改。最后记得import一下。

<?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>com.yky</groupId>
  <artifactId>ssm-test</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

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

  <properties>
    <!-- 设置项目编码编码 -->
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <!-- spring版本号 -->
    <spring.version>4.3.5.RELEASE</spring.version>
    <!-- mybatis版本号 -->
    <mybatis.version>3.4.1</mybatis.version>
    <java.version>12</java.version>
    <maven.compiler.source>12</maven.compiler.source>
    <maven.compiler.target>12</maven.compiler.target>
  </properties>

  <dependencies>

    <!--springmvc-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <!-- 单元测试 -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
    </dependency>

    <!-- 实现slf4j接口并整合 -->
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>1.2.2</version>
    </dependency>

    <!-- JSON -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.8.7</version>
    </dependency>
      <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-annotations</artifactId>
          <version>2.10.0.pr3</version>
      </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.10.0.pr3</version>
    </dependency>

    <!-- 数据库 -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.41</version>
      <scope>runtime</scope>
    </dependency>

    <!-- 数据库连接池 -->
    <dependency>
      <groupId>com.mchange</groupId>
      <artifactId>c3p0</artifactId>
      <version>0.9.5.2</version>
    </dependency>

    <!-- MyBatis -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>${mybatis.version}</version>
    </dependency>

    <!-- mybatis/spring整合包 -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>1.3.1</version>
    </dependency>

    <!-- Spring -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>




    <!-- 数据库 -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.41</version>
      <scope>runtime</scope>
    </dependency>

	<!--servlet API-->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
    </dependency>


  </dependencies>

  <build>
    <finalName>ssm-test</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>3.0.0</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>3.7.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.20.1</version>
          <configuration>
            <skipTests>true</skipTests>
          </configuration>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.0</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>

4.6 增加Mybatis配置文件

在resource目录下创建mybatis.xml文件，该文件只需要针对mapper文件进行配置，数据库连接相关操作不在本文件中配置，交由Spring来管理!

<?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>

    <mappers>
        <!--一会儿会在这里导入Mapper文件-->
    </mappers>
</configuration>

4.7 增加数据库连接基本参数配置文件

在resource目录下新建jdbc.properties,并写入以下内容

database.driver=com.mysql.jdbc.Driver
database.url=jdbc:mysql://localhost:3306/mybatisdb
database.username=root
database.password=123456

4.8 增加Spring配置文件

数据库的连接、SqlSession的创建、Mybatis事务的管理都交由Spring来管理。可以看到Spring配置文件中有读取jdbc.properties文件，拿到数据库的连接参数，从而去链接数据库；Spring配置文件中有配置sqlSessionFactory，并导入了先前创建的mybatis.xml配置文件。
在resource目录下新建applicationContext.xml文件，并写入以下内容:

<?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:aop="http://www.springframework.org/schema/aop"
       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/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 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">


    <!-- 配置数据库相关参数properties的属性：${url} -->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!-- 配置C3P0连接池,目的：管理数据库连接 -->
    <bean id="comboPooledDataSourceID" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${database.driver}"/>
        <property name="jdbcUrl" value="${database.url}"/>
        <property name="user" value="${database.username}"/>
        <property name="password" value="${database.password}"/>
    </bean>


    <!-- 配置SqlSessionFactoryBean，目的：加载mybaits配置文件和映射文件，即替代原Mybatis工具类的作用 -->
    <bean id="sqlSessionFactoryBeanID" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="configLocation" value="classpath:mybatis.xml"/>
        <property name="dataSource" ref="comboPooledDataSourceID"/>
    </bean>


    <!-- 配置Mybatis的事务管理器，即因为Mybatis底层用的是JDBC事务管事器，所以在这里依然配置JDBC事务管理器 -->
    <bean id="dataSourceTransactionManagerID" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="comboPooledDataSourceID"/>
    </bean>

    <!-- 配置事务通知，即让哪些方法需要事务支持 -->
    <tx:advice id="tx" transaction-manager="dataSourceTransactionManagerID">
        <tx:attributes>
            <tx:method name="*" propagation="REQUIRED"/>
        </tx:attributes>
    </tx:advice>

    <!-- 配置事务切面，即让哪些包下的类需要事务 -->
<!--    <aop:config>-->
<!--        <aop:pointcut id="pointcut" expression="execution(* com.yky.service.EmpService.addEmp(..))"/>-->
<!--        <aop:advisor advice-ref="tx" pointcut=""/>-->
<!--    </aop:config>-->

    <!--
        (1)导入jackson-annotations-2.10.0.jar、jackson-core-2.10.0.jar、jackson-databind-2.10.0.jar这三个jar包
        配置JSON适配器
    -->
    <bean id="mappingJackson2HttpMessageConverter"
          class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
                <value>text/json;charset=UTF-8</value>
                <value>application/json;charset=UTF-8</value>
            </list>
        </property>
    </bean>
    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="mappingJackson2HttpMessageConverter"/>
            </list>
        </property>
    </bean>
    <!--开启以注解的方式来管理事务-->
    <tx:annotation-driven transaction-manager="dataSourceTransactionManagerID"/>

    <!--扫描注解-->
    <context:component-scan base-package="com.yky"/>


</beans>

4.9 配置web.xml文件

做好了上面的准备工作后，配置web.xml文件如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xis="http://www.w3.org/2001/XMLSchema-instance"
         xis:schemaLocation="http://java.sun.com/xml/ns/javaee
         http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name>client</display-name>

  <!--配置前置控制器 -->
  <servlet>
    <servlet-name>ClientDispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:applicationContext.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>ClientDispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  
  <filter>
    <filter-name>encodingFilter</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>
    <init-param>
      <param-name>forceEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
  </filter>

  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <!--欢迎文件-->
  <welcome-file-list>
    <welcome-file>/index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

至此，关键配置文件添加完毕!再来看一看目录结构:

5. 配置Tomcat尝试跑一下

基础准备工作已经完成，接下来配置Tomcat尝试跑一下，看欢迎界面能否出来
Run—>Edit Configurations 弹出以下界面

添加Tomcat服务器

按照下面的步骤选择


改一下Application context，改完点确定

运行服务器，访问看一下

6. 类的创建

6.1 创建Employee类

package com.yky.domain;

public class Employee {
    private Integer id;
    private String name;
    private Double salary;
    private String sex;
    public Employee(){}
    public Employee(Integer id, String name, Double salary, String sex) {
        this.id = id;
        this.name = name;
        this.salary = salary;
        this.sex = sex;
    }
    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;
    }
    public Double getSalary() {
        return salary;
    }
    public void setSalary(Double salary) {
        this.salary = salary;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "Emp{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", sal=" + salary +
                ", sex='" + sex + '\'' +
                '}';
    }
}

6.2 创建EmployeeDao类

package com.yky.dao;

import com.yky.domain.Employee;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public class EmployeeDao
{
    @Autowired
    private SqlSessionFactory sqlSessionFactory;

    /**
     * 增加员工
     */
    public void add(Employee emp) throws Exception
    {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        sqlSession.insert("empNamespace.add",emp);
        sqlSession.commit();
    }

    public List<Employee> getAll() throws Exception
    {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession.selectList("empNamespace.getAll");
    }
}

6.3 增加Mapper文件

在resource/mapper下新建EmployeeMapper.xml文件，并填入以下内容

<?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="empNamespace">

    <resultMap type="com.yky.domain.Employee" id="empMap">
        <id property="id" column="eid"/>
        <result property="name" column="ename"/>
        <result property="salary" column="esalary"/>
        <result property="sex" column="esex"/>
    </resultMap>

    <!-- 增加员工 -->
    <insert id="add" parameterType="com.yky.domain.Employee">
        insert into employee(eid,ename,esalary,esex) values(#{id},#{name},#{salary},#{sex})
    </insert>

    <select id="getAll" resultMap="empMap">
        select * from employee;
    </select>

</mapper>

mybatis.xml文件导入Mapper文件

<configuration>

    <mappers>
        <mapper resource="mapper/EmployeeMapper.xml"/>
    </mappers>
</configuration>

6.4 创建EmployeeDao的测试类

测试代码如下:

package com.yky.dao;

import com.yky.domain.Employee;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.List;

import static org.junit.Assert.*;

public class EmployeeDaoTest {

    ApplicationContext applicationContext;
    public void init()
    {
        //加载Spring配置文件
        applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    }
    @Test
    public void add() throws Exception
    {
        Employee employee = new Employee();
        employee.setId(3);
        employee.setName("tom");
        employee.setSalary(11000D);
        employee.setSex("男");

        init();
        EmployeeDao employeeDao = (EmployeeDao) applicationContext.getBean("employeeDao");
        employeeDao.add(employee);
    }

    @Test
    public void getAll() throws Exception {
        init();
        EmployeeDao employeeDao = (EmployeeDao) applicationContext.getBean("employeeDao");
        List<Employee> employees = employeeDao.getAll();
        System.out.println(employees);
    }
}

运行效果:

6.5 创建EmployeeService类，调用Dao层代码

package com.yky.service;

import com.yky.dao.EmployeeDao;
import com.yky.domain.Employee;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
public class EmployeeService
{
    @Autowired
    private EmployeeDao employeeDao;

    @Transactional
    public void addEmp(Employee emp) throws Exception {
        employeeDao.add(emp);
    }

    public List<Employee> getAllEmp() throws Exception{
        return employeeDao.getAll();
    }
}

6.6 创建EmployeeAction类，调用Service层代码

package com.yky.controller;

import com.yky.domain.Employee;
import com.yky.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.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.List;

@Controller
@RequestMapping("/emp")
//@RestController
public class EmployeeAction
{
    @Autowired
    private EmployeeService employeeService;

    @RequestMapping("/register")
    public String register(Model model, Employee emp) throws Exception
    {
        System.out.println("用户注册");
        employeeService.addEmp(emp);
        System.out.println("注册成功");
        model.addAttribute("message","注册成功");
        return "/WEB-INF/jsp/message.jsp";
    }

    @RequestMapping("/getAll")
    public @ResponseBody
    List<Employee> getAll() throws Exception
    {
        System.out.println("获取所有用户");
        return employeeService.getAllEmp();
    }
}

6.7 创建用户注册页面register.jsp

<%--
  Created by IntelliJ IDEA.
  User: danxi
  Date: 2019/10/31
  Time: 9:34
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>员工注册</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/emp/register" method="POST">
    <table border="2" align="center">
        <tr>
            <th>编号</th>
            <td><input type="text" name="id"></td>
        </tr>
        <tr>
            <th>姓名</th>
            <td><input type="text" name="name"></td>
        </tr>
        <tr>
            <th>薪水</th>
            <td><input type="text" name="salary"></td>
        </tr>
        <tr>
            <th>性别</th>
            <td>
                <input type="radio" name="sex" value="男"/>男
                <input type="radio" name="sex" value="女" checked/>女
            </td>
        </tr>
        <tr>
            <td colspan="2" align="center">
                <input type="submit" value="注册"/>
            </td>
        </tr>
    </table>
</form>
</body>
</html>

6.8 创建提示页面message.jsp

<%--
  Created by IntelliJ IDEA.
  User: danxi
  Date: 2019/10/31
  Time: 11:30
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>提示</title>
</head>
<body>
    <h1>${message}</h1>
</body>
</html>

7. 最终效果

浏览器访问http://localhost/register.jsp

成功注册

通过postman成功拿到json数据:

8. 可能遇到的坑

8.1 JDK版本不匹配导致报错

解决方法：
步骤1：file—>Progect structure确保以下几个位置的版本一致



步骤2:settings—>Build,Execution,Deployment—>Compiler—>java Compiler

通过以上两部就解决了JDK版本不一致的问题。

8.2 明明已经在Maven中导入了相关jar包还报错

诸如以下形式的错误：

java.lang.ClassNotFoundException: org.springframework.web.filter.CharacterEncodingFilter

java.lang.ClassNotFoundException: org.springframework.web.servlet.DispatcherServlet

此时查看spring配置文件和web.xml文件中的相关类也可以点进去。

其实问题所在是tomcat的WEB-INF下没有lib文件所致，既然没有，那就把它加进去！
file—>Progect structure—>Artifacts
右键点击最右侧的工程名，选择Put into Output Root，点击后发现左侧的WEB-INF下多了lib文件，这样的话这个问题就解决了！

参考

Mybatis【与Spring整合】
关于IDEA使用maven整合ssm框架