用idea搭建SSM项目,原来这么简单

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前言

前阵子突发奇想,想学习下SpringMVC的源码,于是打算用idea搭建一个简易的maven版SSM案例,也就是SpringMVC+Spring+MyBatis+Maven,因为之前创建过一些Spring的小demo,相关的软件环境已经搭建完成,本以为搭建一个入门级的SSM项目应该不难,谁曾想这个过程中遇到了不少千奇百怪的问题,从开始创建到成功运行花了我整整一个下午的时间(我的午觉啊~~~·),最后项目成功跑起来的时候我长出了一口气,为了以后不在类似的事情上折腾,特此写下这篇文章记录一下搭建过程。

软件环境

先准备好搭建项目的基本环境

Intellij IDEA:2018.1.1

JDK:1.8

Maven:3.6.0

Tomcat:7.0及以上

下载安装好软件后,在idea软件设置里做好JDK、Maven和Tomcat的相关环境配置,这方面网上的资料很多,本文就不介绍了。

创建项目

搭建好环境后,打开idea,点击New - Project

找到Maven一栏,因为要搭建的SpringMvc项目,所以选择webapp模板

填写好GroupId和ArtifactId后,一步步next,最后finish完成

创建成功后,可以看到项目是这样的目录结构

除了配置相关依赖的pom.xml,目录中还有一个文件夹src,src的main目录提供了一个webapp文件夹,webapp文件夹下有一个WEB-INF文件夹,放置的是前端页面的文件,以及web.xml文件。

除了模版提供的目录结构,为了后面项目能成功运行,我们还需要添加一些文件夹,让项目的目录结构变成这样:

数据库文件

首先,先准备好数据库文件,并初始化一条记录

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '用户ID',
  `email` varchar(255) NOT NULL COMMENT '用户邮箱',
  `username` varchar(255) NOT NULL COMMENT '用户昵称',
  `role` varchar(255) NOT NULL COMMENT '用户身份',
  `mobile` varchar(50) DEFAULT '' COMMENT '手机号码',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf-8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', '1589585621@qq.com', 'xjt', 'root', '15678635432');

配置文件

pom.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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.xjt</groupId>
    <artifactId>mvcDemo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>mvcDemo Maven Webapp</name>

    <!-- 用来设置版本号 -->
    <properties>
        <srping.version>4.0.2.RELEASE</srping.version>
        <mybatis.version>3.2.8</mybatis.version>
        <slf4j.version>1.7.12</slf4j.version>
        <log4j.version>1.2.17</log4j.version>
        <druid.version>1.0.9</druid.version>
    </properties>
    <!-- 用到的jar包 -->
    <dependencies>
        <!-- 单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <!-- 表示开发的时候引入,发布的时候不会加载此包 -->
            <scope>test</scope>
        </dependency>

        <!-- spring框架包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-oxm</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${srping.version}</version>
        </dependency>
        <!-- spring框架包 -->
        <!-- mybatis框架包 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>${mybatis.version}</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.2.2</version>
        </dependency>
        <!-- mybatis框架包 -->
        <!-- 数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.35</version>
        </dependency>
        <!-- 导入dbcp的jar包,用来在applicationContext.xml中配置数据库 -->
        <dependency>
            <groupId>commons-dbcp</groupId>
            <artifactId>commons-dbcp</artifactId>
            <version>1.4</version>
        </dependency>
        <!-- jstl标签类 -->
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <!-- log -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- 连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>${druid.version}</version>
        </dependency>
    </dependencies>

    <build>
        <!-- java编译插件,如果maven的设置里配置好jdk版本就不用 -->
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

注:以下四个配置文件都是放置在resources文件夹下

log4j.properties

#日志输出级别
log4j.rootLogger=debug,stdout,D,E

#设置stdout的日志输出控制台
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
#输出日志到控制台的方式,默认为System.out
log4j.appender.stdout.Target = System.out
#设置使用灵活布局
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
#灵活定义输出格式
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} -[%p]  method:[%c (%rms)] - %m%n

jdbc.properties

driver=com.mysql.jdbc.Driver    
url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false    
#数据库的用户名
username=root      
#数据库的密码,别像我一样不设置
password=               
#定义初始连接数
initialSize=0    
#定义最大连接数
maxActive=20    
#定义最大空闲
maxIdle=20    
#定义最小空闲
minIdle=1    
#定义最长等待时间
maxWait=60000

applicationContext.xml

这是Spring的核心配置文件,包括Spring结合Mybatis和数据源的配置信息

<?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: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-3.1.xsd
                        http://www.springframework.org/schema/tx
                        http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <!-- 加载properties文件 -->
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:jdbc.properties"/>
    </bean>

    <!-- 配置数据源 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
    </bean>

    <!-- mybatis和spring完美整合,不需要mybatis的配置映射文件 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!-- 扫描model包 -->
        <property name="typeAliasesPackage" value="com.xjt.model"/>
        <!-- 扫描sql配置文件:mapper需要的xml文件-->
        <property name="mapperLocations" value="classpath:mapper/*.xml"/>
    </bean>

    <!-- Mapper动态代理开发,扫描dao接口包-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 注入sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 给出需要扫描Dao接口包 -->
        <property name="basePackage" value="com.xjt.dao"/>
    </bean>

    <!-- 事务管理 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!--数据库连接池-->
        <property name="dataSource" ref="dataSource"/>
    </bean>

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-3.0.xsd">

    <!-- 扫描注解,这样com.xjt包下的文件都能被扫描 -->
    <context:component-scan base-package="com.xjt"/>

    <!-- 开启SpringMVC注解模式 -->
    <mvc:annotation-driven/>

    <!-- 静态资源默认servlet配置 -->
    <mvc:default-servlet-handler/>
	
	<!-- 配置返回视图的路径,以及识别后缀是jsp文件 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

web.xml

该文件不是放在resources,而是webapp的WEB-INF文件夹下,文件内容如下:

<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">

  <display-name>mvcDemo</display-name>
  <!--项目的欢迎页,项目运行起来后访问的页面-->
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

  <!-- 注册ServletContext监听器,创建容器对象,并且将ApplicationContext对象放到Application域中 -->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <!-- 指定spring核心配置文件 -->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
  </context-param>

  <!-- 解决乱码的过滤器 -->
  <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>

    <init-param>
      <param-name>forceEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <!-- 配置前端控制器 -->
  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!-- 指定配置文件位置和名称 如果不设置,默认找/WEB-INF/<servlet-name>-servlet.xml -->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring-mvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
    <async-supported>true</async-supported>
  </servlet>

  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

</web-app>

运行项目

上面的配置文件编写好之后,其实我们就可以尝试着启动项目了,启动项目前先把applicationContext.xml的内容都注释了,然后就可以创建运行环境了。

点击idea右上角的 Edit Configurations...

选择Tomcat Server - Local,

编辑好项目的启动信息,包括项目名,jdk版本,tomcat以及端口

选择Deployment,添加Atifact,选择第二项,否则Tomcat运行会报错

保存后,启动项目,成功后在浏览器输入http://localhost:8080,返回结果如下:

这是index.jsp文件中的内容,因为index.jsp是启动页,所以项目启动后返回的结果是启动页的内容

<html>
<body>
<h2>Hello World!</h2>
</body>
</html>

编写代码

项目能跑起来,说明我们前端控制器的配置是成功的,接下来要做的是测试能否访问数据库。首先,把基本的类文件创建并编写好代码。

实体类:User.java

package com.xjt.model;

public class User {
    private long id;
    private String email;
    private String mobile;
    private String username;
    private String role;

    public long getId() {
        return id;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }
}

dao文件:IUserDao

package com.xjt.dao;

import com.xjt.model.User;

public interface IUserDao {

    User selectUser(long id);
}

mapper文件:UserDao.xml

位于resources - mapper文件夹下

<?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">

<!-- 设置为IUserDao接口方法提供sql语句配置 -->
<mapper namespace="com.xjt.dao.IUserDao">

    <select id="selectUser" resultType="User" parameterType="long">
        SELECT * FROM user WHERE id = #{id}
    </select>

</mapper>

service接口:IUserService

package com.xjt.service;

import com.xjt.model.User;

public interface IUserService {

    public User selectUser(long userId);
}

UserServiceImpl

package com.xjt.service.impl;

import com.xjt.dao.IUserDao;
import com.xjt.model.User;
import com.xjt.service.IUserService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

@Service("userService")
public class UserServiceImpl implements IUserService {

    @Resource
    private IUserDao userDao;

    public User selectUser(long userId) {
        return userDao.selectUser(userId);
    }
}

controller文件:UserController

package com.xjt.controller;

import com.xjt.model.User;
import com.xjt.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;


@Controller
@RequestMapping("/user")
public class UserController {

    @Autowired
    private IUserService userService;

    @RequestMapping("/select")
    public ModelAndView selectUser() throws Exception {
        ModelAndView mv = new ModelAndView();
        User user = userService.selectUser(1);
        mv.addObject("user", user);
        mv.setViewName("user");
        return mv;
    }
}

UserController定义了一个方法selectUser,读取id为1的User信息,并返回user.jsp页面,访问的路径是/user/select,user.jsp位于 WEB-INF 的 jsp 文件夹下,代码如下:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>user</title>
</head>
<body>
    id:${requestScope.user.id}<br/>
    email:${requestScope.user.email}<br/>
    username:${requestScope.user.username}<br/>
    role:${requestScope.user.role}<br/>
    mobile:${requestScope.user.mobile}<br/>
</body>
</html>

都编写完毕以后,撤销applicationContext.xml文件的注释符号,然后开启项目,成功后在浏览器输入http://localhost:8080/user/select

说明,我们成功访问到了数据库的内容。

至此,SSM项目的搭建大功告成,为了方便大家学习,我把源码放在了github上了,有需要的同学可以自行下载,地址:github.com/Taoxj/mvcDe…