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 ;@Autowiredprivate GamesetService gamesetService;@Autowiredprivate GamesetDao gamesetDao;public GamesetTask() {SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);}@Overridepublic 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1for (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:

@Autowiredprivate GamesetService gamesetService;@Autowiredprivate 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