java类的生命周期

Question

我想要实现在service类中,定义一次通过ThreadLocal类封装的token令牌获取的id值变量,以便我在接下来这个类中任何方法里使用它,而无需进行每个方法都使用一次ThreadLocal,但是老是map为null,我想到的是使用静态代码块在类加载时机就定义好这个id,但是爆了map is null,如果要是将静态代码块中的挪到每个类方法中就可以了,但是我觉得那样比较麻烦,篇幅还长,我对类的声明周期或者其他什么都不了解,这个static还是gpt教给我的

package com.codeCart.service.impl;

import com.codeCart.mapper.ArticleMapper;
import com.codeCart.pojo.Article;
import com.codeCart.service.ArticleService;
import com.codeCart.util.ThreadLocalUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

@Service
public class ArticleServiceImpl implements ArticleService {
    private static Integer id;
    static {
        Map<String,Object> map = ThreadLocalUtils.get();
         id = (Integer) map.get("id");
    }
    @Autowired
    private ArticleMapper articleMapper;
    /**
     * @param article 根据参数查询
     * @return
     */
    @Override
    public List<Article> selectArticle(Article article) {
        article.setId(id);
        return articleMapper.selectArticle(article);
    }

    /**
     * @param article
     */
    @Override
    public void addArticle(Article article) {
        article.setId(id);
        articleMapper.addArticle(article);
    }

    /**
     * @param article
     */
    @Override
    public void updateArticle(Article article) {
        article.setId(id);
        articleMapper.updateArticle(article);
    }

    /**
     * @param title
     */
    @Override
    public void deleteArticle(String title) {
        articleMapper.deleteArticle(title);
    }
}

Answer 1

代码示例如下

public class  ContextHolder {
    private static final ThreadLocal<Map<String,String>> tokenHolder = ThreadLocal.withInitial(() -> {
        return new HashMap<>();
    });
    public static void setValue(String token,String value) {
        Map<String,String> dataMap=tokenHolder.get();
        dataMap.put(dsId,value);

    }

    public static void clear() {
        tokenHolder.remove();
    }
}