按照状态实现自定义排序的方法

news2025/5/31 16:55:20

方法一：使用 MyBatis-Plus 的 QueryWrapper 自定义排序

在查询时动态构建排序规则，通过 CASE WHEN 语句实现优先级排序：

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import org.springframework.stereotype.Service;

@Service
public class ProjectConfigService {

    public List<ProjectConfigEntity> listProjectsByStatusPriority() {
        // 自定义排序：进行中(1) > 已完成(2) > 待启动(0)
        QueryWrapper<ProjectConfigEntity> queryWrapper = new QueryWrapper<>();
        queryWrapper.orderByAsc("CASE " +
                "WHEN project_status = 1 THEN 1 " +  // 进行中排第一
                "WHEN project_status = 2 THEN 2 " +  // 已完成排第二
                "ELSE 3 END");                      // 待启动排第三

        return projectConfigMapper.selectList(queryWrapper);
    }
}

方法二：在实体类中使用 @TableField 注解添加默认排序

如果你希望所有查询都自动应用此排序规则，可以在实体类中添加默认排序注解：

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.IdType;
import lombok.Data;

@Data
@TableName("dste_project_config_new")
public class ProjectConfigEntity implements Serializable {

    private static final long serialVersionUID = 1L;
    
    // 其他字段保持不变...

    /**
     * 项目状态(0:待启动,1:进行中,2:已完成)
     */
    @TableField(value = "project_status", condition = "%s = CASE WHEN project_status = 1 THEN 1 " +
                                                     "WHEN project_status = 2 THEN 2 " +
                                                     "ELSE 3 END")
    private Integer projectStatus;
}

方法三：使用自定义 SQL 查询

如果你需要更复杂的排序逻辑，可以在 Mapper 接口中定义自定义 SQL：

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Select;
import java.util.List;

public interface ProjectConfigMapper extends BaseMapper<ProjectConfigEntity> {

    @Select("SELECT * FROM dste_project_config_new " +
            "ORDER BY CASE " +
            "WHEN project_status = 1 THEN 1 " +
            "WHEN project_status = 2 THEN 2 " +
            "ELSE 3 END")
    List<ProjectConfigEntity> selectProjectsByStatusPriority();
}

方法四：使用 MyBatis-Plus 的 LambdaQueryWrapper自定义排序

    public List<ProjectConfigEntity> listProjectsByStatusPriority() {
        // 使用LambdaQueryWrapper实现类型安全的自定义排序
        LambdaQueryWrapper<ProjectConfigEntity> wrapper = new LambdaQueryWrapper<>();
        wrapper.orderByAsc(true, 
            "CASE " +
            "WHEN project_status = 1 THEN 1 " +  // 进行中排第一
            "WHEN project_status = 2 THEN 2 " +  // 已完成排第二
            "ELSE 3 END");

        return projectConfigMapper.selectList(wrapper);
    }

方法五：避免硬编码表字段名，可以结合实体类的属性名和 SQL 片段

	LambdaQueryWrapper<ProjectConfigEntity> wrapper = new LambdaQueryWrapper<>();
	String statusSortSql = String.format(
	    "CASE " +
	    "WHEN %s = 1 THEN 1 " +
	    "WHEN %s = 2 THEN 2 " +
	    "ELSE 3 END",
	    StringUtils.camelToUnderline(ProjectConfigEntity::getProjectStatus), // 驼峰转下划线
	    StringUtils.camelToUnderline(ProjectConfigEntity::getProjectStatus)
	);
	
	wrapper.orderByAsc(true, statusSortSql);