問(wèn)題描述

使用springboot，和mongo的repository，我定義了一個(gè)Comparator類，想實(shí)現(xiàn)自己的對(duì)象的比較方法。代碼如下：

package com.story.utils;import java.util.Comparator;import javax.annotation.Resource;import org.springframework.stereotype.Service;import com.story.model.Phase;import com.story.model.Story;import com.story.repository.StoryRepository;@Servicepublic class PhaseComparator implements Comparator<Phase>{private String field;private Story story;@Autowired private StoryRepository storyRepository; public PhaseComparator() {super(); } public PhaseComparator (String field) {this.field = field; } @Override public int compare(Phase phase_1, Phase phase_2) {if (this.field.equals('createdDate')) { return phase_1.getCreatedDate() < phase_2.getCreatedDate() ? -1 : 1;} else { Story foundStory_1 = this.storyRepository.findOne(phase_1.getStoryId()); Story foundStory_2 = this.storyRepository.findOne(phase_1.getStoryId()); return foundStory_1.getLastUpdatedDate() < foundStory_2.getLastUpdatedDate() ? -1 : 1;} }}

但是，這樣的話，storyRepository就是null。請(qǐng)問(wèn)應(yīng)該如何處理呢？謝謝

問(wèn)題解答

這樣寫應(yīng)該沒(méi)問(wèn)題，但是你用的時(shí)候必須從 Spring 上下文中去取，比如用 @Autowired 。不知道你是不是這么做的。如果你用的時(shí)候臨時(shí)再去 new PhaseComparator() ，那里面的 storyRepository 肯定是 null。