druid + mybatis-spring使用注解方式整合

1、准备需要的maven依赖

<dependencyManagement>
    <dependencies>
        <!--mysql驱动依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <!--连接池依赖-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>${druid.version}</version>
        </dependency>
        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>${mybatis.version}</version>
        </dependency>
        <!--spring依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--spring-jdcb依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--mybatis-spring依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>${mybatis.spring.version}</version>
        </dependency>
        <!--servlet依赖-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>${servlet.version}</version>
        </dependency>
        <!--gson依赖-->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>${gson.version}</version>
        </dependency>
    </dependencies>
</dependencyManagement>

因为mybatis-spring用到了spring-jdbc里面的东西，所以需要导入依赖

导入了mybatis-spring依赖也还是需要mybatis依赖的。

依赖版本如下：

<spring.version>5.2.0.RELEASE</spring.version>
<druid.version>1.1.20</druid.version>
<mybatis.version>3.5.2</mybatis.version>
<junit.version>4.12</junit.version>
<servlet.version>3.1.0</servlet.version>
<mysql.version>5.1.47</mysql.version>
<gson.version>2.8.5</gson.version>
<mybatis.spring.version>2.0.2</mybatis.spring.version>

2、创建模块

创建出各个模块：entity，util，dao，service，web（按需求增加或减少，不是一定的）

给每个模块的pom.xml文件添加对应需要的依赖。

3、模块操作

3-1 编写entity模块

将需要的实体类编写，添加相应的属性，getter(),setter()，toString()....方法。

3-2 编写util模块

ApplicationContextHolder类：

package com.spring;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class ApplicationContextHolder implements ApplicationContextAware {
    private static ApplicationContext context;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.context = applicationContext;
    }

    public ApplicationContext getContext(){
        return context;
    }

    public static <T>T getBean(String name,Class<?> clz){
        return (T) context.getBean(name,clz);
    }
}

DruidDateSourceFactoryBean类：这个类等价于在applicationContext.xml中直接配置DruidDataSource的bean。

package com.spring;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.FactoryBean;

import javax.sql.DataSource;

public class DruidDateSourceFactoryBean implements FactoryBean<DataSource> {

    @Override
    public DataSource getObject() throws Exception {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl("jdbc:mysql://localhost:3306/empdb");
        dataSource.setUsername("root");
        dataSource.setPassword("root");
        return dataSource;
    }

    @Override
    public Class<?> getObjectType() {
        return DataSource.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

3-3 编写dao模块

EmpDao接口：

package com.dao;

import com.entity.Employee;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface EmpDao {
    //使用注解方式使用查询语句
    @Select("select id,username,salary,gender,hiredate,deptid from employee")
    List<Employee> queryAll();

}

3-4 编写service模块

EmpService接口：

package com.service;

import com.entity.Employee;

import java.util.List;

public interface EmpService {
    List<Employee> queryAll();
}

EmpServiceImpl实现类：

package com.service.impl;

import com.dao.EmpDao;
import com.entity.Employee;
import com.service.EmpService;

import java.util.List;

public class EmpServiceImpl implements EmpService {
    private EmpDao empDao;    //通过依赖注入empDao

    public void setEmpDao(EmpDao empDao) {
        this.empDao = empDao;
    }


    @Override
    public List<Employee> queryAll() {
        return empDao.queryAll();
    }
}

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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--dataSource的bean-->
    <bean id="dataSource" class="com.spring.DruidDateSourceFactoryBean"></bean>
    <!--创建sqlSessionFactory的bean，并且把dataSource通过属性注入进去-->
    <bean id="sqlSessionFatory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--通过MapperFactoryBean类，属性注入接口类型和sqlSessionFactory创建出dao接口的bean-->
    <bean id="empDao" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="com.dao.EmpDao"/>
        <property name="sqlSessionFactory" ref="sqlSessionFatory"/>
    </bean>
    <!--创建empService的bean，属性注入empDao-->
    <bean id="empService" class="com.service.impl.EmpServiceImpl">
        <property name="empDao" ref="empDao"></property>
    </bean>

    <bean class="com.spring.ApplicationContextHolder"></bean>
</beans>

3-5 编写web模块

LoginServlet类：

package com.web;

import com.entity.Employee;
import com.google.gson.Gson;
import com.service.EmpService;
import com.service.impl.EmpServiceImpl;
import com.spring.ApplicationContextHolder;
import org.springframework.context.ApplicationContext;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/select")
public class LoginServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setCharacterEncoding("UTF-8");
        
        EmpService empService = ApplicationContextHolder.getBean("empService",EmpService.class);
        List<Employee> employees = empService.queryAll();
        Gson gson = new Gson();
        resp.getWriter().write(gson.toJson(employees));
    }
}

ApplicationContextInstantiateListener监听器类：

package com.web;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class ApplicationContextInstantiateListener implements ServletContextListener {
//context对象setAttribute的名字
    private static final String SPRING_CONTAINER_KEY = "SPRING_CONTAINER";
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
    //得到上下文对象
        ServletContext servletContext = servletContextEvent.getServletContext();
        //得到上下文对象的值，我们在web.xml设置的applicationContext.xml名字
        String configFille = servletContext.getInitParameter("configFile");
        //得到context对象
        ApplicationContext context = new ClassPathXmlApplicationContext(configFille);
        servletContext.setAttribute(SPRING_CONTAINER_KEY,context);
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {

    }
}

web.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">

    <context-param>
        <param-name>configFile</param-name>
        <!--设置xml名称-->
        <param-value>applicationContext.xml</param-value>
    </context-param>

    <listener>
    <!--绑定监听器类-->
        <listener-class>com.web.ApplicationContextInstantiateListener</listener-class>
    </listener>
</web-app>

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>druid加dbutils加spring查询所有</title>
    <script src="jq/jquery-3.4.1.js"></script>
</head>
<body>
    <div>
        <table>
            <tr>
                <th>编号</th>
                <th>姓名</th>
                <th>工资</th>
            </tr>
            <tbody id="tb1">

            </tbody>
        </table>
    </div>
</body>
<script>
    window.onload = function (ev) {
        loadEmp();
    }
    function loadEmp() {
        $.ajax({
            method:"get",
            url:"/select",
            dataType:"json"
        }).done(function (employees) {
            var tr = "";
            $.each(employees,function (index,emp) {
                tr +="<tr>";
                tr +="<td>"+emp.id+"</td>";
                tr +="<td>"+emp.username+"</td>";
                tr +="<td>"+emp.salary+"</td>";
                tr +="</tr>";
            })
            $("#tb1").html(tr);
        }).fail(function () {
            alert("请求失败")
        })
    }
</script>
</html>

4、知识点总结：

1、mybatis依赖和mybatis-spring依赖是必须要添加的。

2、dao接口使用注解Select注入SQL语句。

3、使用MapperFactoryBean类创建出特殊的接口bean。