Preface

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Mybatis plus not only can operate the database for objects like HIbernate, but also supports mybatis to write native SQL. And can automatically generate dao, service, controler layer additions, deletions, and methods according to the table, which greatly improves development efficiency.

Integration steps:

pom.xml introduces the jar package:

	 <!-- 添加mybatisplus  -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatisplus-spring-boot-starter</artifactId>
            <version>${mybatisplus.boot.version}</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>${mybatisplus.version}</version>
        </dependency>

application.yml configures mybatis plus information:

mybatis-plus:
  mapper-locations: classpath:com/*/mapper/*.xml
  #实体扫描，多个package用逗号或者分号分隔
  typeAliasesPackage: com.common.model
  global-config:
    #主键类型  0:"数据库ID自增", 1:"用户输入ID",2:"全局唯一ID (数字类型唯一ID)", 3:"全局唯一ID UUID";
    id-type: 0
    #字段策略 0:"忽略判断",1:"非 NULL 判断"),2:"非空判断"
    field-strategy: 2
    #驼峰下划线转换
    db-column-underline: true
    #刷新mapper 调试神器
    refresh-mapper: true
    #数据库大写下划线转换
    #capital-mode: true
    #逻辑删除配置（下面3个配置）
    logic-delete-value: 1
    logic-not-delete-value: 0
    sql-injector: com.baomidou.mybatisplus.mapper.LogicSqlInjector
  configuration:
    #配置返回数据库(column下划线命名&&返回java实体是驼峰命名)，自动匹配无需as（没开启这个，SQL需要写as： select user_id as userId）
    map-underscore-to-camel-case: true
    cache-enabled: false
    #配置JdbcTypeForNull, oracle数据库必须配置
    jdbc-type-for-null: 'null'

Mapper.xml written:

<?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.enjoypark.dao.StudentDao">

   <!-- 通用查询映射结果 -->
   <resultMap id="BaseResultMap" type="com.enjoypark.model.Student">
      <id column="id" property="id" />
      <result column="name" property="name" />
      <result column="sex" property="sex" />
      <result column="password" property="password" />
      <result column="create_time" property="createTime" />
   </resultMap>

    <!-- 通用查询结果列 -->
    <sql id="Base_Column_List">
        id, name, sex, password, create_time
    </sql>

	<select id="selectListPage" resultMap="BaseResultMap">
	    SELECT <include refid="Base_Column_List" />
	    from student t
		where 1=1
		<if test="student!=null and student.id!=null">
			and t.id=#{student.id}
		</if>
		<if test="student!=null and student.name!=null">
			and t.name=#{student.name}
		</if>
		<if test="student!=null and student.sex!=null">
			and t.sex=#{student.sex}
		</if>
		<if test="student!=null and student.password!=null">
			and t.password=#{student.password}
		</if>
		<if test="student!=null and student.createTime!=null">
			and t.create_time=#{student.createTime}
		</if>
	</select>
</mapper>

dao layer writing:

package com.enjoypark.dao;

import com.baomidou.mybatisplus.mapper.BaseMapper;
import com.baomidou.mybatisplus.plugins.Page;
import com.enjoypark.model.Student;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Map;

/**
 * <p>
  *  Dao 接口
 * </p>
 *
 * @author wangPeng
 * @since 2019-08-28
 */
@Repository()
public interface StudentDao extends BaseMapper<Student> {
    
    

	  /**
	   * mybatis-plus 和mybatis结合分页查询
	   * @return
	   */
	  public List<Student> selectListPage(Page<Map> mapPage, @Param("student") Student student);
}

Write the service layer interface:

package com.enjoypark.service;

import com.enjoypark.model.Student;
import com.baomidou.mybatisplus.service.IService;

import java.util.List;
import java.io.Serializable;

/**
 * <p>
 *  服务类
 * </p>
 *
 * @author wangPeng
 * @since 2019-08-28
 */
public interface StudentService extends IService<Student> {
    
    

    /**
	 * 分页查询
	 * mybatis-plus 和mybatis结合分页查询
	 * @param userQu
	 * @param firstStart
	 * @param pageSize
	 * @return
	 */
    public List<Student> getBypage(Student studentQu, int firstStart, int pagesize);

    /**
     * 查询表记录总数
     */
    public Long getAllCount(Student studentQu);

     /**
     * 根据实体保存
     */
    public int saveStudent(Student student);

    /**
     * 根据id查询实体
     */
    public Student getByID(Serializable studentID);

     /**
     * 根据实体Id更新
     */
    public int updateStudent(Student student);

    /**
     * 根据Id删除
     */
    public int deleteByID(Serializable studentID);
}

Write the service impl implementation class:

package com.enjoypark.service.impl;

import java.io.Serializable;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.baomidou.mybatisplus.mapper.EntityWrapper;
import com.baomidou.mybatisplus.plugins.Page;

import com.enjoypark.model.Student;
import com.enjoypark.dao.StudentDao;
import com.enjoypark.service.StudentService;
import com.baomidou.mybatisplus.service.impl.ServiceImpl;
/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author wangPeng
 * @since 2019-08-28
 */
@Service
public class StudentServiceImpl extends ServiceImpl<StudentDao, Student> implements StudentService {
    
    


    @Autowired
    private StudentDao studentDao;

	/**
	 * 分页查询
	 * mybatis-plus 和mybatis结合分页查询
	 * @param userQu
	 * @param firstStart
	 * @param pageSize
	 * @return
	 */
	@Override
    public List<Student> getBypage(Student studentQu, int firstStart, int pagesize)
    {
    
    
        return studentDao.selectListPage(new Page<>(firstStart,pagesize),studentQu);
    }

    /**
     * 查询表记录总数
     */
    @Override
    public Long getAllCount(Student studentQu){
    
    
        return studentDao.selectCount(new EntityWrapper<Student>()).longValue();
    }

     /**
     * 根据实体保存
     */
    @Override
    public int saveStudent(Student student){
    
    
    	return studentDao.insert(student);
    }

    /**
     * 根据id查询实体
     */
    @Override
    public Student getByID(Serializable studentID) {
    
    
    	return studentDao.selectById(studentID);
    }

     /**
     * 根据实体Id更新(updateById只更新有值得字段，updateAllColumById所有字段都更新)
     */
    @Override
    public int updateStudent(Student student){
    
    
    	return studentDao.updateById(student);
    }

    /**
     * 根据Id删除
     */
    @Override
    public int deleteByID(Serializable studentID){
    
    
       return studentDao.deleteById(studentID);
    }
}

Write the control layer class:

package com.enjoypark.controller;

import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.shiro.authz.annotation.RequiresPermissions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

import com.util.DateUtil;
import com.util.SubmitMessage;

import com.enjoypark.service.StudentService;
import com.enjoypark.model.Student;

/**
 *
 * @author wangPeng
 * @since 2018-10-11
 * Student表的视图层
 */

@Controller
@Scope("prototype")
@SuppressWarnings("all")
@RequestMapping("/student")
public class StudentController {
    
    

    @Autowired
    public StudentService studentService;

    //分页时对应的列表用户信息
    private List<Student> studentList; // 把jsp中的字段变量封装
    // 异步操作操作返回的信息
    private SubmitMessage submitMessage = new SubmitMessage();
    private Student student;//当前实体

    /**
     * 跳转列表页面
     * @param request
     * @param model
     * @return
     */
    @RequiresPermissions("student:getStudent")
    @RequestMapping(value = "getStudent",method= RequestMethod.POST)
    public ModelAndView getStudent()
    {
    
    
    	return new ModelAndView("/student");
    }


	/**
     * 异步获取用户的信息列表
     * @param String page,String rows
     * @return Map<String, Object>
     */
    @RequiresPermissions("student:getStudentBypage")
    @RequestMapping(value ="getStudentBypage",method= RequestMethod.POST)
    //@ResponseBody 表示返回的数据不是html标签格式，如json,xml等数据
  	@ResponseBody
    public Map<String, Object> getStudentBypage(String page,String rows,Student student)
    {
    
    

        // 返回总记录数
        String total = Integer.toString(studentService.getAllCount(null).intValue());

        // 当前页
        int intPage;
        if (page == null || page.equals("0")){
    
    
            intPage = 1;
        }
        else{
    
    
            intPage = Integer.parseInt(page);
        }

        // 每页显示条数
        int number;
        if (rows== null || rows.equals("0")){
    
    
            number = 10;
        }else {
    
    
            number = Integer.parseInt(rows);
        }

        // 每页的开始记录 第一页为1 第二页为number +1
        int start = (intPage - 1) * number;

        // 查询所有的用户信息
        studentList = studentService.getBypage(student, start, number);

        Map<String, Object> jsonMap = new HashMap<String, Object>();// 定义map
        jsonMap.put("total", total);// total键 存放总记录数，必须的
        jsonMap.put("rows", studentList);// rows键 存放每页记录 list

        return jsonMap;
    }

	/**
     * 根据Id删除
     *
     * @return
     */
    @RequiresPermissions("student:deleteStudent")
    @RequestMapping(value="deleteStudent",method= RequestMethod.POST)
    @ResponseBody
    public SubmitMessage deleteSysuser(String studentID)
    {
    
    
		//获取删除成功的记录个数
				int result=studentService.deleteByID(Integer.parseInt(studentID));


        if(result>0){
    
    
    		submitMessage.setSuccess(true);
    		submitMessage.setInfo("删除成功");
    	}else{
    
    
    		submitMessage.setSuccess(false);
    		submitMessage.setInfo("数据库记录不存在");
    	}

        return submitMessage;
    }

    /**
     * 修改或新增前查询
     *
     * @return
     */
    @RequestMapping(value="saveorupdateStudentBefore",method= RequestMethod.GET)
    public ModelAndView saveorupdateStudentBefore(String studentID)
    {
    
    
    	ModelAndView modelAndView=new ModelAndView();
    	if(!StringUtils.isEmpty(studentID)){
    
    
    		student = studentService.getByID(Integer.parseInt(studentID));
    	}

        //设置前台接收的实体
        modelAndView.addObject("student",student);
        //设置页面视图
        modelAndView.setViewName("studentAdd");
        return modelAndView;
    }

     /**
     * 根据页面传递的信息，保存或修改数据库信息
     *
     * @return
     */
    @RequiresPermissions("student:saveorupdateStudent")
    @RequestMapping(value="saveorupdateStudent",method= RequestMethod.POST)
    @ResponseBody
    public SubmitMessage saveorupdateSysuser(Student student)
    {
    
    
		boolean isSave = student.getId() == null || student.getId().equals(0);

        String strtime = DateUtil.formatDateByFormat(new Date(),DateUtil.DATETIME_FORMAT2);

        int result=0;
        if (isSave){
    
    
            result=studentService.saveStudent(student);
        }
        else{
    
    
           result=studentService.updateStudent(student);
        }


        if(result>0){
    
    
    		submitMessage.setSuccess(true);
    		submitMessage.setInfo("删除成功");
    	}else{
    
    
    		submitMessage.setSuccess(false);
    		submitMessage.setInfo("数据库记录不存在");
    	}

        return submitMessage;
    }

}

Effect test:

Source address:

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