MybatisPlus分页Page插件

分页Page插件

首先，要在配置类中注册MyBatisPlus的核心插件，同时添加分页插件。设置分页查询的配置类,interceptor只有拦截作用，功能需要自己添加。这里我们添加上分页查询功能。

import com.baomidou.mybatisplus.annotation.DbType;
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;

@Configuration //标记为配置类
public class MyBatisConfig {
    @Bean //设置该注解后可以在SpringBoot中直接通过@Autowired注入到其他类中
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        //设置MybatisPlus分页插件的拦截器
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        //1.创建分页插件
        PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor(DbType.MYSQL);
        paginationInnerInterceptor.setMaxLimit(1000L);
        //2.添加分页插件
        interceptor.addInnerInterceptor(paginationInnerInterceptor);
        return interceptor;
    }
}

Test案例，OrderItem中true升序排序，false降序

    @Test
    void testPageQuery() {

        int pageNo = 1; // 当前页码
        int pageSize = 5; // 每页显示条数
        //1.准备分页条件
        //1.1分页条件
        Page<User> page = Page.of(pageNo, pageSize);
        page.addOrder(new OrderItem("balance", true));
        page.addOrder(new OrderItem("id", true));
        //2.分页查询
        Page<User> p = iUserService.page(page);
        //3.解析
        long total = p.getTotal();
        System.out.println("total = " + total);
        long size = p.getSize();
        System.out.println("size = " + size);
        List<User> list = p.getRecords();
        list.forEach(System.out::println);
    }

案例

要求：
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PageQuery

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

@Data
@ApiModel(description = "分页查询实体类")
public class PageQuery {
    @ApiModelProperty("页码")
    private Integer pageNo;
    @ApiModelProperty("每页大小")
    private Integer pageSize;
    @ApiModelProperty("排序字段")
    private String sortBy;
    @ApiModelProperty("是否升序")
    private Boolean isAsc;

}

UserQuery继承PageQuery使其能接收Page相关参数

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;

@EqualsAndHashCode(callSuper = true)//继承父类属性的equals和hashCode方法
@Data
@ApiModel(description = "用户查询条件实体")
public class UserQuery extends PageQuery {
    @ApiModelProperty("用户名关键字")
    private String name;
    @ApiModelProperty("用户状态：1-正常，2-冻结")
    private Integer status;
    @ApiModelProperty("余额最小值")
    private Integer minBalance;
    @ApiModelProperty("余额最大值")
    private Integer maxBalance;
}

PageDTO为分页查询结果

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.List;


@Data
@NoArgsConstructor
@AllArgsConstructor
@ApiModel(description = "分页结果")
public class PageDTO<T> {
    @ApiModelProperty("总条数")
    private Long total;
    @ApiModelProperty("总页数")
    private Long pages;
    @ApiModelProperty("当前页数据")
    private List<T> list;


}

控制层

    @ApiOperation("根据条件分页查询用户接口")
    @GetMapping("/page")
    public PageDTO<UserVO> queryUserPage(UserQuery userQuery) {
        return iUserService.queryUsersPage(userQuery);
    }

Service层

PageDTO<UserVO> queryUsersPage(UserQuery userQuery);

Impl层

 @Override
    public PageDTO<UserVO> queryUsersPage(UserQuery query) {
        String name = query.getName();
        Integer status = query.getStatus();
        //1.构建分页条件
        //1.1分页条件
        Page<User> page = Page.of(query.getPageNo(), query.getPageSize());
        //1.2排序条件
        if (StrUtil.isNotBlank(query.getSortBy())) {
            //不为空
            page.addOrder(new OrderItem(query.getSortBy(), query.getIsAsc()));
        } else {
            //为空，默认按照更新时间排序
            page.addOrder(new OrderItem("update_time", false));
        }

        //2.分页查询

        Page<User> p = lambdaQuery()
                .like(name != null, User::getUsername, name)
                .eq(status != null, User::getStatus, status)
                .page(page);

        //3.封装VO对象
        PageDTO<UserVO> dto = new PageDTO<>();
        //3.1总条数
        dto.setTotal(p.getTotal());
        //3.2总页数
        dto.setPages(p.getPages());
        //3.3当前页数据
        List<User> records = p.getRecords();
        if (CollUtil.isEmpty(records)) {
            dto.setList(Collections.emptyList());
            return dto;
        }
        //3.4拷贝user的vo
        dto.setList(BeanUtil.copyToList(records, UserVO.class));
        return dto;
    }