java中MybatisPlus中常见的案例,通用Mapper通用Service,以及XML书写SQL语句进行增删改查常见操作

package com.czxy; import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper; import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper; import com.baomidou.mybatisplus.extension.plugins.pagination.Page; import com.czxy.domain.Student; import com.czxy.mapper.StudentMapper; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import javax.annotation.Resource; import java.beans.Customizer; import java.util.Arrays; import java.util.Date; import java.util.List; @RunWith(SpringJUnit4ClassRunner.class) @SpringBootTest(classes = TestStudentApplication.class) public class TestMapper_01_student { @Resource private StudentMapper studentMapper; //1.查询所有 @Test public void selectAll(){ List<Student> list = studentMapper.selectList(null); list.forEach(System.out::println); } //1.1分页查询 @Test public void testPage(){ int current=1; int size=3; Page<Student> page = new Page<>(current, size); studentMapper.selectPage(page, null); System.out.println("总共记录数:"+page.getRecords()); page.getRecords().forEach(System.out::println); } //1.2分页条件查询 @Test public void testPageByCondition(){ //条件 String sname="三"; int age=18; QueryWrapper<Student> queryWrapper = new QueryWrapper<>(); //姓名中包含三的 且年龄大于等于19的 queryWrapper.like(sname!=null&&!"".equals(sname),"sname",sname); queryWrapper.ge("age",age); //分页 int current=1; int size=3; Page<Student> page = new Page<>(current, size); //查询 studentMapper.selectPage(page, queryWrapper); page.getRecords().forEach(System.out::println); } //2.添加 @Test public void insertStudent(){ Student student = new Student(); student.setSid("s007"); student.setSname("lihua"); int insert = studentMapper.insert(student); System.out.println(insert); } //3.修改 @Test public void updateStudent(){ //要修改成这个信息 Student student = new Student("s003", "赵san三", 19, new Date(), '0', "c001"); //不能修改成重名的 UpdateWrapper<Student> queryWrapper = new UpdateWrapper<>(); queryWrapper.ne("s_id",student.getSid()); queryWrapper.eq("sname",student.getSname()); Student selectOne = studentMapper.selectOne(queryWrapper); System.out.println(selectOne); if(selectOne!=null){ //改成和别人重名了 System.err.println("修改失败了"); }else { //更新 // studentMapper.update(student, queryWrapper); studentMapper.updateById(student); System.out.println("修改成功了"); } } //4.删除 @Test public void deleteStudent(){ int i = studentMapper.deleteById("s007"); System.out.println(i); } //批量删除 @Test public void deleteBatchs(){ studentMapper.deleteBatchIds(Arrays.asList("s007","s008","s009")); } }