在非Spring容器中使用注入

        在做项目的时候,往往有很多情况是会在非Spring的容器下需要用到Spring管理的组件的,比如说:定时器,servlet,拦截器等等,在这种情况下通常都想使用数据库操作的时候都会感觉到乏力,因为在这种环境下,你要调用相关的Dao层的东西,往往想用依赖注入来实现,卻每每跑出来的就都是空指针异常.

        举个例子说明:

public class TaskManager implements ServletContextListener {
	// 每天的毫秒数
	public static final long DAY = 86400000;
	// 定时器
	private Timer timer;

	// @Autowired
	// private GamesetTask gamesetTask;

	/**
	 * 在Web应用结束时停止任务
	 */
	public void contextDestroyed(ServletContextEvent sce) {
		timer.cancel();// 定时器销毁

	}

	/**
	 * 在Web应用启动时初始化任务
	 */
	public void contextInitialized(ServletContextEvent sce) {
		SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);

		// 定义定时器
		Calendar c = Calendar.getInstance();
		c.add(Calendar.DATE, 1);
		c.set(c.get(Calendar.YEAR), c.get(Calendar.MONTH), c.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
		timer = new Timer(true);
		GamesetTask gamesetTask = new GamesetTask();// 定时执行的内容
		// timer.schedule(locationTask, c.getTime(), DAY); //定时器在每日凌晨0点执行
		timer.schedule(gamesetTask, 5000, 4 * 60 * 1000); // 启动后5秒执行,后每隔1小时在执行
//		timer.schedule(gamesetTask, 5000, 5 * 1000);
	}
}

这是个很非同的定时器,目的是在服务启动时定时执行GamesetTask任务

具体的任务如下:

package com.smartsoft.task;

import java.util.Date;
import java.util.TimerTask;

import net.sf.json.JSONObject;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.RequestEntity;
import org.apache.commons.httpclient.methods.StringRequestEntity;
import org.apache.commons.lang.math.RandomUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.context.support.SpringBeanAutowiringSupport;

import com.smartsoft.common.Constants;
import com.smartsoft.dao.GamesetDao;
import com.smartsoft.service.GamesetService;

@Component("gamesetTask")
public class GamesetTask extends TimerTask {
	private static boolean isRunning = false;
	private static int t = 1 ;
	private static int i = 1 ;

	@Autowired
	private GamesetService gamesetService;
	
	@Autowired
	private GamesetDao gamesetDao;

	public GamesetTask() {
		SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
	}
	
	@Override
	public void run() {
		if (!isRunning) {
			isRunning = true;
			System.out.println("-----ganmeset add-------");
			addGemest();
			isRunning = false;
		} else {
			System.out.println("-----ganmeset error-------");
		}
	}

	private void addGemest() {
		if(t==1){
			System.out.println("---------request:newGameSet-------------");
			sendHttpRequest("{\"api_key\":\"test"+i+"\",\"table_no\":\"A001\",\"computer_name\":\"computer001\",\"game_set\":\""+i+"\",\"shoe_of_the_day\":\""+i+"\",\"game_time\":\""+new Date()+"\",\"status\":\"1\"}", "http://127.0.0.1:8080/bdb/gameset!newGameSet", Constants.HTTP_CONTENT_TYPE_APPLICATION_JSON);
		}else{
			int ttt = RandomUtils.nextInt(3);
			String res = "";
			if(ttt==0){
				res = "T";
			}else if(ttt==1){
				res = "B";
			}else{
				res = "P";
			}
			System.out.println("---------request:submitGameResult-------------");
			sendHttpRequest("{\"api_key\":\"test"+i+"\",\"table_no\":\"A001\",\"computer_name\":\"computer001\",\"game_set\":\""+i+"\",\"shoe_of_the_day\":\""+i+"\",\"game_time\":\""+new Date()+"\",\"game_no\":\""+i+"\",\"active_game_no\":\""+i+"\",\"win\":\""+res+"\",\"win_type\":\"\",\"banker_pair\":\""+RandomUtils.nextInt(2)+"\",\"player_pair\":\""+RandomUtils.nextInt(2)+"\",\"status\":\"1\"}", "http://127.0.0.1:8080/bdb/gameset!submitGameResult", Constants.HTTP_CONTENT_TYPE_APPLICATION_JSON);
			i++;
			System.out.println("---------request:newGameSet-------------");
			sendHttpRequest("{\"api_key\":\"test"+i+"\",\"table_no\":\"A001\",\"computer_name\":\"computer001\",\"game_set\":\""+i+"\",\"shoe_of_the_day\":\""+i+"\",\"game_time\":\""+new Date()+"\",\"status\":\"1\"}", "http://127.0.0.1:8080/bdb/gameset!newGameSet", Constants.HTTP_CONTENT_TYPE_APPLICATION_JSON);
		}
		t++;
	}
	
	/**
	 * httpClient
	 * @param reqStr
	 * @param urlConfig
	 * @param contentType
	 * @return
	 */
	private int sendHttpRequest(String reqStr,String urlConfig,String contentType) {
		try {
			PostMethod postMethod = new PostMethod(urlConfig);
			RequestEntity requestEntity  = new StringRequestEntity(reqStr,contentType,Constants.CONTENT_ENCODING_UTF8);
			postMethod.setRequestEntity(requestEntity);
			HttpClient httpClient = new HttpClient();
			httpClient.executeMethod(postMethod);
			JsonResultModel jsonResult=(JsonResultModel)JSONObject.toBean(JSONObject.fromObject(postMethod.getResponseBodyAsString()),JsonResultModel.class);
			int httpStatus = Integer.parseInt(jsonResult.getStatus());
			return httpStatus;
		} catch (Exception e) {
			return 500;
		}
	}
	
	public static void main(String[] args) {
		//随机数0或1
		for (int i = 0; i < 50; i++) {
			System.out.println(RandomUtils.nextInt(2));
			
		}
	}

}

以上是我定制的一个定时任务,用httpClient不断请求本地环境某项目的url地址,虽然这里没有操作任何数据库的代码,然是如果某天需要增加需求,在记录每次任务请求返回的数据请,并保存于数据库,或者更具请求给过做出相应的操作,如发邮件什么的,这种情况多用于检测服务器是否运行正常的情况.既然要操作数据库就会想运用相关的dao进行CRUD,如果单纯的在代码敲这几行:

@Autowired
	private GamesetService gamesetService;
	
	@Autowired
	private GamesetDao gamesetDao;

那保证是空指针,应为这里没有被Spring容器所管理,自然不会被注入,那么怎么解决的呢?

办法很多

网上有人公布怎么获取ioc上下文的,这个也很好明白,但是代码量就比较多,如果有兴趣了解,可以度娘关键字"Web项目中获取SpringBean"

这里我的写法是引入

SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);

这是Spring的自动装备,有了他前面的注解就不会空指针了,而且代码也美观,整洁

如果有什么不懂,大家可以留言或者问下度娘咯,反正我也是问度娘多