1. 程式人生 > >SpringContextHolder 獲取bean

SpringContextHolder 獲取bean

使用註解形式進行載入,實現ApplicationContextAware介面並複寫setApplicationContext方法。

將上下文環境物件以靜態變數儲存下來。則可以在工具類中使用SpringContextHolder.getBean()的方法獲取實體或者service進行操作資料

使用@Service註解形式進行實體注入

package com.hema.common.utils;

import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Date;

import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Service;


/**
 * 以靜態變數儲存Spring ApplicationContext, 可在任何程式碼任何地方任何時候取出 
 * ApplicaitonContext.
 * 
 * @date 2013-5-29 下午1:25:40
 */
@Service
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

	private static ApplicationContext applicationContext = null;

	private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

	/**
	 * 取得儲存在靜態變數中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		assertContextInjected();
		return applicationContext;
	}

	/**
	 * 從靜態變數applicationContext中取得Bean, 自動轉型為所賦值物件的型別.
	 */
	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) applicationContext.getBean(name);
	}

	/**
	 * 從靜態變數applicationContext中取得Bean, 自動轉型為所賦值物件的型別.
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext為Null.
	 */
	public static void clearHolder() {
		if (logger.isDebugEnabled()){
			logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
		}
		applicationContext = null;
	}

	/**
	 * 實現ApplicationContextAware介面, 注入Context到靜態變數中.
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) {
		SpringContextHolder.applicationContext = applicationContext;
	}

	/**
	 * 實現DisposableBean介面, 在Context關閉時清理靜態變數.
	 */
	@Override
	public void destroy() throws Exception {
		SpringContextHolder.clearHolder();
	}

	/**
	 * 檢查ApplicationContext不為空.
	 */
	private static void assertContextInjected() {
		Validate.validState(applicationContext != null, "applicaitonContext屬性未注入, 請在applicationContext.xml中定義SpringContextHolder.");
	}
}