1.mybatis-plus之通用 CRUD 封装BaseMapper
本文章主要演示如何使用mybatis-plus的接口BaseMapper实现CURD相关操作，演示环境为Idea+maven+spring+mybatis，并使用单元测试的形式展示。
1.maven环境pom.xml
<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>4.0.0modelVersion>
<groupId>org.examplegroupId>
<artifactId>MP1artifactId>
<version>1.0-SNAPSHOTversion>
<dependencies>
<dependency>
<groupId>com.baomidougroupId>
<artifactId>mybatis-plusartifactId>
<version>2.3version>
dependency>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.9version>
dependency>
<dependency>
<groupId>log4jgroupId>
<artifactId>log4jartifactId>
<version>1.2.17version>
dependency>
<dependency>
<groupId>com.mchangegroupId>
<artifactId>c3p0artifactId>
<version>0.9.5.2version>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>5.1.37version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>4.3.10.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-ormartifactId>
<version>4.3.10.RELEASEversion>
dependency>
dependencies>
project>
2. POJO类：Emp.java
package com.qwy.bean;
import com.baomidou.mybatisplus.annotations.TableField;
import com.baomidou.mybatisplus.annotations.TableId;
import com.baomidou.mybatisplus.enums.IdType;
import java.util.Date;
/**
* @author qwy
* @create 2021-04-09 8:41
**/
public class Emp {
/*设置主键名称默认为id*/
@TableId(value = "empno",type = IdType.INPUT)
private Integer empno;
private String ename;
private String job;
private Integer mgr;
private Date hiredate;
private Float sal;
private Float comm;
private Integer deptno;
public Emp() {
}
public Emp(Integer empno, String ename, String job, Integer mgr, Date hiredate, Float sal, Float comm, Integer deptno) {
this.empno = empno;
this.ename = ename;
this.job = job;
this.mgr = mgr;
this.hiredate = hiredate;
this.sal = sal;
this.comm = comm;
this.deptno = deptno;
}
public Integer getEmpno() {
return empno;
}
public void setEmpno(Integer empno) {
this.empno = empno;
}
public String getEname() {
return ename;
}
public void setEname(String ename) {
this.ename = ename;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public Integer getMgr() {
return mgr;
}
public void setMgr(Integer mgr) {
this.mgr = mgr;
}
public Date getHiredate() {
return hiredate;
}
public void setHiredate(Date hiredate) {
this.hiredate = hiredate;
}
public Float getSal() {
return sal;
}
public void setSal(Float sal) {
this.sal = sal;
}
public Float getComm() {
return comm;
}
public void setComm(Float comm) {
this.comm = comm;
}
public Integer getDeptno() {
return deptno;
}
public void setDeptno(Integer deptno) {
this.deptno = deptno;
}
@Override
public String toString() {
return "Emp{" +
"empno=" + empno +
", ename='" + ename + '\'' +
", job='" + job + '\'' +
", mgr=" + mgr +
", hiredate=" + hiredate +
", sal=" + sal +
", comm=" + comm +
", deptno=" + deptno +
'}';
}
}
3. 持久层接口：EmpMapper.java
注意：继承BaseMapper接口
package com.qwy.mapper;
import com.baomidou.mybatisplus.mapper.BaseMapper;
import com.qwy.bean.Emp;
/**
* @author qwy
* @create 2021-04-14 23:35
**/
public interface EmpMapper extends BaseMapper<Emp> {
}
4.数据库资源文件：db.properties
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mydb
jdbc.username=root
jdbc.password=admin
5. 日志文件：log4j.xml
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
<param name="Encoding" value="UTF-8" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
layout>
appender>
<logger name="java.sql">
<level value="debug" />
logger>
<logger name="org.apache.ibatis">
<level value="info" />
logger>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
root>
log4j:configuration>
6.mybatis的核心配置文件：mybatis-config.xml
<configuration>
configuration>
7.spring的全局配置文件：applicationContext.xml
<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:tx="http://www.springframework.org/schema/tx"
xmlns:mybatis-spring="http://mybatis.org/schema/mybatis-spring"
xsi:schemaLocation="http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring-1.2.xsd
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-4.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
<context:property-placeholder location="classpath:db.properties"/>
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="${jdbc.driver}">property>
<property name="jdbcUrl" value="${jdbc.url}">property>
<property name="user" value="${jdbc.username}">property>
<property name="password" value="${jdbc.password}">property>
bean>
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource">property>
bean>
<tx:annotation-driven transaction-manager="transactionManager"/>
<bean id="sqlSessionFactoryBean" class="com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean">
<property name="dataSource" ref="dataSource">property>
<property name="configLocation" value="classpath:mybatis-config.xml">property>
<property name="typeAliasesPackage" value="com.atguigu.mp.beans">property>
<property name="globalConfig" ref="globalConfiguration">property>
bean>
<property name="dbColumnUnderline" value="true">property>
<property name="idType" value="0">property>
bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.qwy.mapper">property>
bean>
beans>
8.通用CURD测试类
package com.qwy.test;
import com.qwy.bean.Emp;
import com.qwy.mapper.EmpMapper;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import javax.sql.DataSource;
import java.util.Arrays;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
/**
* @author qwy
* @create 2021-04-14 23:36
**/
public class TestCommonCURD {
private EmpMapper empMapper=null;
@Before
public void getApplicationContext(){
ApplicationContext ac= new ClassPathXmlApplicationContext("applicationContext.xml");
empMapper=ac.getBean("empMapper",EmpMapper.class);
}
/**
* 添加：
* insert()方法，会将设置为null属性对应字段忽略
*/
@Test
public void testInsert(){
Emp emp= new Emp(1111, "admin", "CLERK", 7788, null, 2000F,null, 10);
//SQL:INSERT INTO emp ( empno, ename, job, mgr, sal, deptno ) VALUES ( ?, ?, ?, ?, ?, ? )
Integer insert = empMapper.insert(emp);
System.out.println("insert = " + insert);
}
/**
* 添加
* insertAllColumn(),会将属性为null的字段也在SQL操作
*
*/
@Test
public void testInsertAllColumn(){
Emp emp= new Emp(3333, "admin", "CLERK", 7788, null, 2000F,null, 10);
//SQL:INSERT INTO emp ( empno,ename,job,mgr,hiredate,sal,comm,deptno ) VALUES ( ?,?,?,?,?,?,?,? )
Integer insert = empMapper.insertAllColumn(emp);
System.out.println("insert = " + insert);
}
/**
* 根据id更新操作：
* updateById();根据id更新，忽略为null的字段
*/
@Test
public void testUpdateById(){
Emp emp= new Emp(1111, "齐老师", "CLERK", 7788, null, 2000F,null, 10);
//SQL:UPDATE emp SET ename=?, job=?, mgr=?, sal=?, deptno=? WHERE empno=?
Integer integer = empMapper.updateById(emp);
System.out.println("integer = " + integer);
}
/**
* 根据id更新操作：
* 会将属性为null的字段也在SQL操作
*/
@Test
public void testUpdateAllColumnById(){
Emp emp= new Emp(1111, "齐大大", "CLERK", 7788, null, 2000F,null, 10);
//SQL:UPDATE emp SET ename=?,job=?,mgr=?,hiredate=?,sal=?,comm=?,deptno=? WHERE empno=?
Integer integer = empMapper.updateAllColumnById(emp);
System.out.println("integer = " + integer);
}
/**
* 根据id删除
*/
@Test
public void testDeleteById(){
//SQL:DELETE FROM emp WHERE empno=?
Integer integer = empMapper.deleteById(1111);
System.out.println("integer = " + integer);
}
/**
* 根据id批量删除
*/
@Test
public void testDeleteBatchIds(){
//SQL:DELETE FROM emp WHERE empno IN ( ? , ? , ? )
Integer integer = empMapper.deleteBatchIds(Arrays.asList(2222,3333,4444));
System.out.println("integer = " + integer);
}
/**
* 根据条件删除：
* map的key为字段，value为字段的值
*/
@Test
public void testDeleteByMap(){
Map<String,Object> conditons= new HashMap<String, Object>();
conditons.put("empno",1111);
conditons.put("ename","admin");
//SQL: DELETE FROM emp WHERE ename = ? AND empno = ?
Integer integer = empMapper.deleteByMap(conditons);
System.out.println("integer = " + integer);
}
}
9.get获取测试类
package com.qwy.test;
import com.baomidou.mybatisplus.plugins.Page;
import com.qwy.bean.Emp;
import com.qwy.mapper.EmpMapper;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author qwy
* @create 2021-04-14 23:36
**/
public class TestGet {
private EmpMapper empMapper=null;
@Before
public void getApplicationContext(){
ApplicationContext ac= new ClassPathXmlApplicationContext("applicationContext.xml");
empMapper=ac.getBean("empMapper",EmpMapper.class);
}
/**
* 根据主键查询
*/
@Test
public void testSelectById(){
//SQL:SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE empno=?
Emp emp = empMapper.selectById(7788);
System.out.println("emp = " + emp);
}
/**
* 根据条件查询单个实体，如果返回多条数据，报错
*/
@Test
public void testSelectOne(){
Emp conditions= new Emp();
conditions.setEmpno(7788);
conditions.setEname("SCOTT");
//SQL:SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE empno=? AND ename=?
Emp emp = empMapper.selectOne(conditions);
System.out.println("emp = " + emp);
}
/**
* 根据id批量查询
*/
@Test
public void testSelectBatchIds(){
//SQL:SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE empno IN ( ? , ? , ? )
List<Emp> emps = empMapper.selectBatchIds(Arrays.asList(7788, 1111, 7369));
System.out.println("emps = " + emps);
}
/**
* 使用map集合作为条件
*/
@Test
public void testSelectByMap(){
Map<String ,Object> conditions=new HashMap<String, Object>();
conditions.put("deptno",30);
//SQL:SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE deptno = ?
List<Emp> emps = empMapper.selectByMap(conditions);
for (int i = 0; i < emps.size(); i++) {
System.out.println("emps = " + emps.get(i));
}
}
/**
* 分页：基于内存的分页
*
*/
@Test
public void testSelectPage(){
//SQL:SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp
List<Emp> emps = empMapper.selectPage(new Page<Emp>(1,3),null);
for (int i = 0; i < emps.size(); i++) {
System.out.println("emps = " + emps.get(i));
}
}
}
10. 条件构造测试类
package com.qwy.test;
import com.baomidou.mybatisplus.mapper.Condition;
import com.baomidou.mybatisplus.mapper.EntityWrapper;
import com.baomidou.mybatisplus.mapper.Wrapper;
import com.baomidou.mybatisplus.plugins.Page;
import com.qwy.bean.Emp;
import com.qwy.mapper.EmpMapper;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author qwy
* @create 2021-04-14 23:36
**/
public class TestEntityWrapper {
private EmpMapper empMapper=null;
@Before
public void getApplicationContext(){
ApplicationContext ac= new ClassPathXmlApplicationContext("applicationContext.xml");
empMapper=ac.getBean("empMapper",EmpMapper.class);
}
/**
* 根据主键查询
*/
@Test
public void testSelectCount(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",30);
wrapper.like("ename","A");
Integer count = empMapper.selectCount(wrapper);
System.out.println("count = " + count);
}
/**
* 根据条件查询返回list集合封装的Map集合结果：
* map的key为字段名，value为对应字段的值
*/
@Test
public void testSelectMaps(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",30);
wrapper.like("ename","A");
//SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE (deptno = ? AND ename LIKE ?)
List<Map<String, Object>> list = empMapper.selectMaps(wrapper);
System.out.println("list = " + list);
}
/**
* 条件查询，返回list集合封装的对象
*
*/
@Test
public void testSelectList(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",30);
wrapper.like("ename","A");
//SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE (deptno = ? AND ename LIKE ?)
List<Emp> emps = empMapper.selectList(wrapper);
System.out.println("emps = " + emps);
}
/**
* 基于内存的分页查询方式
* 返回list集合封装的对象
*/
@Test
public void testSelectPage(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",30);
wrapper.like("ename","A");
//SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE (deptno = ? AND ename LIKE ?)
List<Emp> emps = empMapper.selectPage(new Page<Emp>(2,3),wrapper);
System.out.println("emps = " + emps);
}
/**
* 基于内存的分页查询方式
* 返回list集合封装的map集合
*/
@Test
public void testSelectMapsPage(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",30);
wrapper.like("ename","A");
//SELECT empno AS empno,ename,job,mgr,hiredate,sal,comm,deptno FROM emp WHERE (deptno = ? AND ename LIKE ?)
List<Map<String, Object>> maps = empMapper.selectMapsPage(new Page<Emp>(2, 3), wrapper);
System.out.println("maps = " + maps);
}
/**
* 根据条件修改
*/
@Test
public void testUpdate(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",10);
wrapper.eq ("empno","1111");
Emp emp= new Emp(1111, "aaaa", "CLERK", 7788, null, 2000F,null, 10);
// UPDATE emp SET ename=?, job=?, mgr=?, sal=?, deptno=? WHERE (deptno = ? AND empno = ?)
Integer update = empMapper.update(emp, wrapper);
System.out.println("update = " + update);
}
/**
* 根据条件删除
*/
@Test
public void testDelete(){
EntityWrapper<Emp> wrapper = new EntityWrapper<Emp>();
wrapper.eq("deptno",10);
wrapper.eq ("empno","1111");
// DELETE FROM emp WHERE (deptno = ? AND empno = ?)
Integer delete = empMapper.delete(wrapper);
System.out.println("delete = " + delete);
}
/**
* 根据条件删除
*/
@Test
public void testDelete2(){
Condition condition = Condition.create();
condition.eq("deptno",10);
condition.eq ("empno","1111");
// DELETE FROM emp WHERE (deptno = ? AND empno = ?)
Integer delete = empMapper.delete(condition);
System.out.println("delete = " + delete);
}
}
11.常用CURD方法整理
11.1Insert
// 插入一条记录
int insert(T entity);
11.2.Delete
// 根据 entity 条件，删除记录
int delete(@Param(Constants.WRAPPER) Wrapper wrapper);
// 删除（根据ID 批量删除）
int deleteBatchIds(@Param(Constants.COLLECTION) Collection idList);
// 根据 ID 删除
int deleteById(Serializable id);
// 根据 columnMap 条件，删除记录
int deleteByMap(@Param(Constants.COLUMN_MAP) Map columnMap);
11.3.Update
// 根据 whereEntity 条件，更新记录
int update(@Param(Constants.ENTITY) T entity, @Param(Constants.WRAPPER) Wrapper updateWrapper);
// 根据 ID 修改
int updateById(@Param(Constants.ENTITY) T entity);
11.4.Select
// 根据 ID 查询
T selectById(Serializable id);
// 根据 entity 条件，查询一条记录
T selectOne(@Param(Constants.WRAPPER) Wrapper queryWrapper);
// 查询（根据ID 批量查询）
List selectBatchIds(@Param(Constants.COLLECTION) Collection idList);
// 根据 entity 条件，查询全部记录
List selectList(@Param(Constants.WRAPPER) Wrapper queryWrapper);
// 查询（根据 columnMap 条件）
List selectByMap(@Param(Constants.COLUMN_MAP) Map columnMap);
// 根据 Wrapper 条件，查询全部记录
List> selectMaps(@Param(Constants.WRAPPER) Wrapper queryWrapper);
// 根据 Wrapper 条件，查询全部记录。注意： 只返回第一个字段的值
List 转载请加入出处