在servlet中如何使用被Spring管理的service

    我的使用场景是SpringMvc+MyBatis，我总结了以下两种方式，三种方法。两种方式指的是采用注入方式和获取spring管理的bean。三种方法指的是，代理注入、硬编码获取bean和实现ApplicationContextAware接口获取bean。

    第一种方式：采用注入方式。

    编写一个代理类，代码如下：

@SuppressWarnings("serial")
public class ProxyServlet extends HttpServlet {

	@Override
	public void service(ServletRequest req, ServletResponse res)
			throws ServletException, IOException {
		proxyServlet.service(req, res);
	}

	@Override
	public void init() throws ServletException {
		this.targetBean = getServletName();
		getServletBean();
		proxyServlet.init(getServletConfig());
	}

	private String targetBean;
	
	private Servlet proxyServlet;
	
	private void getServletBean(){
		WebApplicationContext wac = WebApplicationContextUtils
				.getRequiredWebApplicationContext(getServletContext());
		this.proxyServlet = (Servlet) wac.getBean(targetBean);
	}
}

    然后编写需要注入service的servlet，代码如下：

 

 

 

@Component
public class MemcacheServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	@Autowired
	private GlobalCacheService globalCacheService;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public MemcacheServlet() {
        super();
        
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String flag = request.getParameter("flag");
		globalCacheService.test();
		if("q".equals(flag)){
			//取缓存
			String name = (String)globalCacheService.getCacheValue("_name1", Object.class);
			System.out.println("执行取缓存操作： " + name);
		}else if("f".equals(flag)){
			//放缓存
			String username = request.getParameter("username");
			globalCacheService.deleteCacheValue("_name1");
			if(!StringUtil.isBlank(username)){
				System.out.println("执行存缓存操作： " + username);
				globalCacheService.setCacheValue("_name1", username, 28800);
			}else{
				System.out.println("执行存缓存操作： " + username);
				globalCacheService.setCacheValue("_name1", "lzx", 28800);
			}
		}
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html");
		this.doGet(request, response);
	}

}

    最后在web.xml中配置如下：

<servlet>
	<servlet-name>memcacheServlet</servlet-name>
    <servlet-class>com.hsis.core.servlet.web.ProxyServlet</servlet-class>
  </servlet>
<servlet-mapping>
	<servlet-name>memcacheServlet</servlet-name>
	<url-pattern>*.to</url-pattern>
  </servlet-mapping>

    第二种方式：获取spring管理的service，采用硬编码或者实现AplicationContextAware接口。

      2.1 采用硬编码方法如下：

     

ApplicationContext ctx = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);
或者
WebApplicationContext wac = WebApplicationContextUtils.getWebApplicationContext(servletContext);
LzxService lzxService = (LzxService)wac.getBean("lzxService");

    注：WebApplicationContext继承的ApplicationContext。

      2.2 采用实现AplicationContextAware接口方法，首先创建一个类SpringContextUtil，代码如下：

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class SpringContextUtil implements ApplicationContextAware {
	
	private static ApplicationContext applicationContext;

	@Override
	public void setApplicationContext(ApplicationContext applicationContext)
			throws BeansException {
		applicationContext = applicationContext;
	}
	
	public static ApplicationContext getApplicationContext(){
		return applicationContext;
	}
	
	public static Object getBean(String name){
		return applicationContext.getBean(name);
	}
	
	public static <T> T getBean(String name, Class<T>  requiredClass){
		return applicationContext.getBean(name, requiredClass);
	}

}

 applicationContext.xml中配置一下：

 

 

 

<bean class=”SpringContextUtil” />

 

     在servlet中使用即可：

globalCacheService = (GlobalCacheService) SpringContextUtil.getBean("globalCacheService", GlobalCacheService.class);

     注：实现Aware接口的类，初始化之后可以获取对应的资源，实现ApplicationContextAware接口的bean，初始化后被注入applicationContext实例。

      如果使用ClassPathXmlApplicationContext、FileSystemClassPathXmlApplicationContext和FileSystemXmlApplicationContext等对象去加载Spring配置文件，会生成一个新的application对象，这样会产生冗余。