druid + mybatis-spring 不使用注解方式整合分页查询

1、准备需要的maven依赖

<dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
        </dependency>

        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
        </dependency>
    </dependencies>

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>
<jstl.version>1.2</jstl.version>
<mybatis.spring.version>2.0.2</mybatis.spring.version>
<pageHelper.version>5.1.10</pageHelper.version>

2、创建模块

创建出各个模块：entity，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 {
    List<Employee> queryAll();

}

3-3 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" xmlns:mybatis="http://mybatis.org/schema/mybatis-spring"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<!--普通创建dataSource的bean方法-->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
    <property name="url" value="jdbc:mysql://localhost:3306/empdb"/>
    <property name="username" value="root"/>
    <property name="password" value="root"/>
</bean>
<!--创建sqlSessionFactory-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <!--传入dataSource-->
    <property name="dataSource" ref="dataSource"/>
    <!--读取employeeMapper.xml文件-->
    <property name="mapperLocations" value="classpath:employeeMapper.xml"/>
    <!--开启日志-->
    <property name="configuration">
        <bean class="org.apache.ibatis.session.Configuration">
            <property name="logImpl" value="org.apache.ibatis.logging.stdout.StdOutImpl"/>
        </bean>
    </property>
    <!--开启分页-->
    <property name="plugins">
        <list>
            <bean class="com.github.pagehelper.PageInterceptor">
                <property name="properties">
                    <value>
                        supportMethodsArguments=true
                        resonable=true
                    </value>
                </property>
            </bean>
        </list>
    </property>
</bean>
<!--自动生成com.dao包下的所有类的bean-->
<mybatis:scan base-package="com.dao"/>
<!--自动注入empService需要的bean-->
<bean id="empService" class="com.service.impl.EmpServiceImpl" autowire="byType"/>

</beans>

employeeMapper.xml

使用employeeMapper.xml能够保留mybatis的优点，更加灵活，降低依赖耦合

<?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="com.dao.EmpDao">
    <select id="queryByPageNum" resultType="com.entity.Employee">
        select id,username,salary from employee order by id
    </select>
</mapper>

3-4 编写web模块

PageEmpServlet类：

package com.controller;

import com.entity.Employee;
import com.github.pagehelper.PageInfo;
import com.service.EmpService;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

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("/pageEmp")
public class PageEmpServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        Integer pageNum = 1;
        try {
            pageNum = Integer.valueOf(req.getParameter("pageNum"));
        }catch (NullPointerException e){
            throw new RuntimeException("未发现指定参数",e);
        }finally {
            //得到context对象，通过web.xml绑定的监听类的方法创建，单一
            ApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(req.getServletContext());
            EmpService empService = context.getBean("empService", EmpService.class);
            List<Employee> employees = empService.queryByPageNum(pageNum, 5);
            PageInfo<Employee> pageInfo = new PageInfo<>(employees);
            req.setAttribute("pageInfo",pageInfo);
            req.getRequestDispatcher("index.jsp").forward(req,resp);
        }
    }
}

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">
    <!--绑定容器配置文件-->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext2.xml</param-value>
    </context-param>
    <!--设置监听器，这个监听器帮我们实现了创建单一的context容器对象-->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
</web-app>

index.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: 李威
  Date: 2019/10/24
  Time: 15:20
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>分页查询</title>
</head>
<body>
    <table>
        <c:forEach items="${pageInfo.list}" var="emp">
            <tr>
                <td>${emp.id}</td>
                <td>${emp.username}</td>
                <td>${emp.salary}</td>
            </tr>
        </c:forEach>
        <tr>
            <td><a href="/pageEmp?pageNum=1">首页</a></td>
            <td><a href="/pageEmp?pageNum=${pageInfo.prePage}">上一页</a><a href="/pageEmp?pageNum=${pageInfo.nextPage}">下一页</a></td>
            <td><a href="/pageEmp?pageNum=${pageInfo.navigateLastPage}">尾页</a></td>
        </tr>
    </table>
</body>
</html>

4、知识点总结：

1、保留了employeeMapper.xml文件

2、使用了依赖jar包的监听类ContextLoaderListener

3、使用pagehelper实现分页

4、自动生成dao，自动注入dao到Service中