Java-載入順序

前景

• 公司要求做個重複提交的小程式
• 內網做業務，向公網平臺推送資料
• 斷網不影響業務，網路連線上了，繼續推送，資料不丟失

package com.hfrl.cache;

import com.hfrl.dao.CacheMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.*;
import java.util.concurrent.TimeUnit;

/**
 * 資料保護 of Dete 2018-12-03 By Chenyb
 */
@Component
public class CacheListMap {

    //成員變數
    private final static String MSG_SUCCESS = "SUCCESS";
    private final static String MSG_ERROR = "ERROR";
    private final static String MSG_NULL = "NULL";

    private static List<Map<String , Object>> cacheList = new ArrayList<>();
    private static long timeOut = 500 ;
    private static boolean config = true ;

    /*持久層注入*/
    @Autowired
    private static CacheMapper cacheMapper;

    @Autowired
    public CacheListMap(CacheMapper cacheMapper){

        this.cacheMapper = cacheMapper ;
    }

    /*推送資料方法*/
    public String pushData ( Map<String , String> dateMap){

        System.out.println("cacheList :" + cacheList.size());

        if((cacheList == null|| cacheList.size() ==0) && config){

            cacheList = initCache();
        }
        if (dateMap != null){

            //資料處理
            Map map = new HashMap();
            String uuid = UUID.randomUUID().toString().replace("-", "");
            String cachedata = dateMap.toString().replace("=", ":");//.substring(1, dateMap.toString().length() - 1).replace("=", ":");
            map.put("UUID" , uuid);
            map.put("CACHEDATA",cachedata);

            cacheList.add(map);//新資料加入快取

            Integer addInt = addCache(uuid, cachedata);//新資料持久化
            if(addInt < 0 ){
                cacheList.remove(map);
            }
            System.out.println(cacheList.get(0));
        }

       if(cacheList != null){

           try {
               int countType = 0;

               StringBuffer strBf = new StringBuffer();
               for (Map<String, Object> objectMap : cacheList) {

                   System.out.println(objectMap.get("UUID"));
                   System.out.println(objectMap.get("CACHEDATA"));

                   //推送程式碼
                   strBf.substring(1,cacheList.size() +1 );

                   strBf.append("," + objectMap.get("UUID"));
                   countType += 1;
               }

               if (countType == cacheList.size()){

                   //成功，刪除mysql中對應的資料
                   timeOut = 500 ;
                   Integer delInt = delCache(strBf.substring(1).toString());//資料刪除
                   if (delInt > 0) {
                       cacheList.clear();//快取清空
                       countType = 0;
                   }
                   return MSG_SUCCESS;
               }
               return MSG_ERROR;
           }catch (Exception e) {

               timeOut = timeOut * 2;
               if(timeOut > 1000*60)
                   timeOut = 1000*60*2;//最大間隔
               System.out.println(new Date().toString() + ":" + timeOut);
               recursionCache(timeOut);
               return MSG_ERROR;
           }
       }
       return MSG_NULL;
    }

    /*初始化*/
    private List<Map<String , Object>> initCache (){

        config = false ;
        return cacheMapper.getCache();
    }

    /*新增呼叫*/
    private Integer addCache (String uuid , String cachedata){

        return this.cacheMapper.addCache(uuid , cachedata);
    }

    /*刪除呼叫*/
    private Integer delCache (String uuids){

        return this.cacheMapper.delCache("(" + uuids + ")");
    }

    /*遞迴呼叫*/
    private String recursionCache(long timeOut){

        try {

            TimeUnit.MILLISECONDS.sleep(timeOut);//等待時間
            pushData(null);

        } catch (Exception e1) {
            new Exception("CacheListMap睡死過去了！");
        }

        return MSG_ERROR;
    }

    public static void main(String[] args) {

    }
}
 

DAO介面注入是個問題，由於載入順序，介面注入物件，一直為空，報錯：初始化異常，空指標等

@Autowired 構造方法方式注入

• 靜態變數或靜態語句塊（按宣告順序）
• 非靜態變數或構造程式碼塊（按宣告順序）
• 構造方法
• @Value/@Autowired等註解

隨筆記錄，方便自己學習

2018-12-05