java 分页查询

1、配置分页插件

操作模块：service-uitl，service公共资源

说明：我们将@MapperScan("com.atguigu.system.mapper")提取到该配置类上面，统一管理，启动类就不需要了。

package com.atguigu.system.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;

/**
 * MybatisPlus配置类
 *
 */
@EnableTransactionManagement
@Configuration
@MapperScan("com.atguigu.system.mapper")
public class MybatisPlusConfig {

    /**
     *
     * @return
     */
    @Bean
    public MybatisPlusInterceptor addPaginationInnerInterceptor(){
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        //向Mybatis过滤器链中添加分页拦截器
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }

}

2、分页controller

@ApiOperation(value = "获取分页列表")
@GetMapping("/{page}/{limit}")
public Result index(
        @ApiParam(name = "page", value = "当前页码", required = true)
        @PathVariable Long page,

        @ApiParam(name = "limit", value = "每页记录数", required = true)
        @PathVariable Long limit,

        @ApiParam(name = "roleQueryVo", value = "查询对象", required = false)
                SysRoleQueryVo roleQueryVo) {
    Page<SysRole> pageParam = new Page<>(page, limit);
    IPage<SysRole> pageModel = sysRoleService.selectPage(pageParam, roleQueryVo);
    return Result.ok(pageModel);
}

3、service

IPage<SysRole> selectPage(Page<SysRole> pageParam, SysRoleQueryVo roleQueryVo);

@Override
public IPage<SysRole> selectPage(Page<SysRole> pageParam, SysRoleQueryVo roleQueryVo) {

    return sysRoleMapper.selectPage(pageParam, roleQueryVo);
}

4、SysRoleQueryVo 内容

package com.atguigu.model.vo;

import java.io.Serializable;

/**
 * <p>
 * 角色查询实体
 * </p>
 *
 * @author qy
 * @since 2019-11-08
 */
public class SysRoleQueryVo implements Serializable {
	
	private static final long serialVersionUID = 1L;
	
	private String roleName;

	public String getRoleName() {
		return roleName;
	}

	public void setRoleName(String roleName) {
		this.roleName = roleName;
	}
}

5、mapper

IPage<SysRole> selectPage(Page<SysRole> page, @Param("vo") SysRoleQueryVo roleQueryVo);

6、xml

在resources目录下创建mapper/SysRoleMapper.xml文件

说明：分页我们统一定义到xml文件中，更方便直观

<?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.atguigu.system.mapper.SysRoleMapper">

    <resultMap id="RoleMap" type="com.atguigu.model.system.SysRole" autoMapping="true">
    </resultMap>

    <!-- 用于select查询公用抽取的列 -->
    <sql id="columns">
        id,role_name,role_code,description,create_time,update_time,is_deleted
    </sql>

    <select id="selectPage" resultMap="RoleMap">
        select <include refid="columns" />
        from sys_role
        <where>
            <if test="vo.roleName != null and vo.roleName != ''">
                and role_name like CONCAT('%',#{vo.roleName},'%')
            </if>
            and is_deleted = 0
        </where>
        order by id desc
    </select>

</mapper>