mybatis-plus 高级搜索分页功能的实现 sql语句 QueryWrapper 条件判断

mybatis-plus分页功能的实现
创建一个mybatisplus的项目。

配置类mybatisConfig.java 开启。

写service层的方法。

mybatisConfig.java
package com.ppl.mybatispage.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.autoconfigure.ConfigurationCustomizer;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @author ppliang
 * @date 2020/12/24 19:57
 */
@Configuration
public class MybatisConfig {

    /**
     * 新的分页插件,一缓和二缓遵循mybatis的规则,需要设置 MybatisConfiguration#useDeprecatedExecutor = false 避免缓存出现问题
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        //注释下面的可能出现获取不到总数的效果
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }

    @Bean
    public ConfigurationCustomizer configurationCustomizer() {
        return configuration -> configuration.setUseDeprecatedExecutor(false);
    }

}
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EmployeeServiceImpl.java
package com.ppl.mybatispage.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.ppl.mybatispage.dao.EmployeeMapper;
import com.ppl.mybatispage.entity.Employee;
import com.ppl.mybatispage.service.EmployeeService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * @author ppliang
 * @date 2020/12/24 19:51
 */
@Service
public class EmployeeServiceImpl extends ServiceImpl<EmployeeMapper,Employee> implements EmployeeService {

    @Resource
    private EmployeeMapper employeeMapper;

    /**
     * 分页自带包装类
     *   QueryWrapper 进行条件判断
     * @param page
     * @param employee
     * @return
     */
    @Override
    public IPage<Employee> pageEmployee(IPage<Employee> page, Employee employee) {
        // https://baomidou.com/guide/wrapper.html
        // Page<Employee> page=new Page<>(pageNum,pageSize); 设置页数
        QueryWrapper<Employee> employeeQueryWrapper = new QueryWrapper<>();
        //设置查询性别
        employeeQueryWrapper.eq("gender", employee.getGender());
        IPage<Employee> employeeIPage = employeeMapper.selectPage(page, employeeQueryWrapper);
        return employeeIPage;
    }

    /**
     * 分页自带包装类
     *   QueryWrapper 自定义SQL语句
     * @param page
     * @param employee
     * @return
     */
    @Override
    public IPage<Employee> pageEmployee2(IPage<Employee> page,Employee employee) {
        IPage<Employee> employeeIPage = employeeMapper.pageEmployee2(page, employee);
        return employeeIPage;
    }
}
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EmployeeMapper.java
/**
 * @author ppliang
 * @date 2020/12/24 19:50
 */
public interface EmployeeMapper extends BaseMapper<Employee> {

    IPage<Employee> pageEmployee2(IPage<Employee> page, Employee employee);
}
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EmployeeMapper.xml
<?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.ppl.mybatispage.dao.EmployeeMapper">

     <select id="pageEmployee2" resultType="com.ppl.mybatispage.entity.Employee">
        SELECT *
        FROM t_employee
        <where>
            <if test="param2.gender !=null and param2.gender != '' ">
               and  gender = #{param2.gender}
            </if>
        </where>
    </select>
</mapper>
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一开始没有总数显示出来，就是在配置类中没有指明数据库类型！！！！

interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
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版权声明：本文为CSDN博主「黄二马」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/xiaoliang98/article/details/111657612