springboot+mybatis-plus分页和条件查询

springboot+mybatis-plus分页和条件查询

mybatis-plus分页查询拥有内置的page方法，前端页面向后台传入page和limit，后台调用page()方法可以得到分页结果。

分页

在Controller中添加分页方法

@ApiOperation(value = "分页讲师列表")
@GetMapping("{page}/{limit}")
public R pageList(
    @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){

    Page pageParam = new Page<>(page, limit);

    teacherService.page(pageParam, null);
    List records = pageParam.getRecords();
    long total = pageParam.getTotal();

    return  R.ok().data("total", total).data("rows", records);
}

条件查询

1、创建com.guli.edu.query包，创建TeacherQuery.java查询对象

package com.guli.edu.query;

@ApiModel(value = "Teacher查询对象", description = "讲师查询对象封装")
@Data
public class TeacherQuery implements Serializable {

	private static final long serialVersionUID = 1L;

	@ApiModelProperty(value = "教师名称,模糊查询")
	private String name;

	@ApiModelProperty(value = "头衔 1高级讲师 2首席讲师")
	private Integer level;
    
	@ApiModelProperty(value = "查询开始时间", example = "2019-01-01 10:10:10")
	private String begin;//注意，这里使用的是String类型，前端传过来的数据无需进行类型转换

	@ApiModelProperty(value = "查询结束时间", example = "2019-12-01 10:10:10")
	private String end;
}

将前端查询条件封装成查询条件对象。

2、service

service层接口声明方法

package com.guli.edu.service;
public interface TeacherService extends IService {

	void pageQuery(Page pageParam, TeacherQuery teacherQuery);
}

service层实现类实现方法：

package com.guli.edu.service.impl;

@Service
public class TeacherServiceImpl extends ServiceImpl implements TeacherService {

	@Override
	public void pageQuery(Page pageParam, TeacherQuery teacherQuery) {

		QueryWrapper queryWrapper = new QueryWrapper<>();
		queryWrapper.orderByAsc("sort");

		if (teacherQuery == null){
			baseMapper.selectPage(pageParam, queryWrapper);
			return;
		}

		String name = teacherQuery.getName();
		Integer level = teacherQuery.getLevel();
		String begin = teacherQuery.getBegin();
		String end = teacherQuery.getEnd();

		if (!StringUtils.isEmpty(name)) {
			queryWrapper.like("name", name);
		}

		if (!StringUtils.isEmpty(level) ) {
			queryWrapper.eq("level", level);
		}

		if (!StringUtils.isEmpty(begin)) {
			queryWrapper.ge("gmt_create", begin);
		}

		if (!StringUtils.isEmpty(end)) {
			queryWrapper.le("gmt_create", end);
		}

		baseMapper.selectPage(pageParam, queryWrapper);
	}
}

3、controller

在Controller层中增加pageQuery()方法

@ApiOperation(value = "分页讲师列表")
@GetMapping("{page}/{limit}")
public R pageQuery(
    @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 = "teacherQuery", value = "查询对象", required = false)
    TeacherQuery teacherQuery){

    Page pageParam = new Page<>(page, limit);

    teacherService.pageQuery(pageParam, teacherQuery);
    List records = pageParam.getRecords();
    long total = pageParam.getTotal();

    return  R.ok().data("total", total).data("rows", records);
}

总结

mybatis-plus自带的分页功能十分方便，平时我们编写前端时，分页是经常用到的，善于调用mybatis-plus自带的分页和条件查询能够提高我们的编程效率。希望这篇文章能对你有帮助，感谢你的阅读。我是黑马Jack，一起学习一起进步！