專案中遇到這樣一個問題,當時是要寫一個工具類,裡面有這樣的一段話,
MsgTools是工具類,裡面有一個屬性applicationContext

MsgTools.applicationContext
          .getBean(com.cheshangma.operation.wx.service.internal.WeChatServiceImpl.class)

但這樣會報錯,applicationContext一直是null,不能注入進來,聽公司大牛解釋就是,載入MsgTools類時,ApplicationContext類還沒有被spring代理載入,所以不能注入進MsgTools這個類裡面.解決的思路就是要讓ApplicationContext這個類先被spring先管理注入,然後在去載入管理MsgTools這個類.

程式碼如下

package com.cheshangma.operation.wx.common.utils;

import java.util.HashMap;
import java.util.Map;

import org.apache.log4j.Logger;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext
 
;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Configuration;

import com.cheshangma.operation.common.enums.MessageType;
import com.cheshangma.operation.entity.NoticeEventEntity;
import com.cheshangma.operation.wx.common.template.CarCertifiMsg
 
;
import com.cheshangma.operation.wx.common.template.CarIllegalMsg;
import com.cheshangma.operation.wx.common.template.CarNoticeMsg;
import com.cheshangma.operation.wx.common.template.EventReply;
import com.cheshangma.operation.wx.common.template.MsgTemplate;
import com.cheshangma.operation.wx.common.template.OrderNewMsg;
import com.cheshangma.operation.wx.common.template.OrderPayMsg;
import com.cheshangma.operation.wx.common.template.OrderShipMsg;
import com.cheshangma.operation.wx.common.template.WxTemplate;
import com.cheshangma.operation.wx.service.MsgService;
import com.cheshangma.operation.wx.service.NoticeEventService;


/**
 * 根據通知型別不同調用不同service傳送訊息
 * 
 * @author yhy
 *
 */
@Configuration
public class MsgTools implements ApplicationContextAware {//這裡實現ApplicationContextAware介面
  @SuppressWarnings("unused")
  private static Logger log = Logger.getLogger(MsgTools.class);

  public static int TIME_INTERVAL = 1;
  public static int SLEEP_TIME = 10 * 1000;
  /** 存入memcached的時間 **/
  public static int MEM_TIME = (TIME_INTERVAL + 1) * 60 * 1000;
  private static Map<MessageType, Object> map = new HashMap<MessageType, Object>();
  private static NoticeEventService noticeEventService = null;
  private static MsgTools msgTools = new MsgTools();
  private static boolean isReloaded = false;
  private static ApplicationContext applicationContext;










  public static MsgTools getInstance() {
    return msgTools;
  }








  public boolean sendOneMsg(MessageType msgType, MsgTemplate msgTemplate) {
    synchronized (MsgTools.class) {
      while (!isReloaded) {//ApplicationContext類沒有載入完,讓執行緒等待
        try {
          MsgTools.class.wait();
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
      MsgService msgService = (MsgService) map.get(msgType);
      return msgService.sendMsg(msgTemplate);
    }
  }


  @Override
  public void setApplicationContext(ApplicationContext arg0) throws BeansException {
  //這裡就是讓ApplicationContext載入完後,在使用ApplicationContext來獲得bean
    synchronized (MsgTools.class) {
      MsgTools.applicationContext = arg0;
      isReloaded = true;
      map.put(MessageType.MSGTYPE_WEIXIN, MsgTools.applicationContext
          .getBean(com.cheshangma.operation.wx.service.internal.WeChatServiceImpl.class));
      map.put(MessageType.MSGTYPE_SMS, MsgTools.applicationContext
          .getBean(com.cheshangma.operation.wx.service.internal.SmsServiceImpl.class));
      map.put(MessageType.MSGTYPE_VOICE, MsgTools.applicationContext
          .getBean(com.cheshangma.operation.wx.service.internal.VoiceServiceImpl.class));
      noticeEventService =
          (NoticeEventService) MsgTools.applicationContext
              .getBean(com.cheshangma.operation.wx.service.internal.NoticeEventServiceImpl.class);
      MsgTools.class.notifyAll();
    }

  }

}