在servlet中如何使用被Spring管理的service
2023-04-12
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：
memcacheServlet
com.hsis.core.servlet.web.ProxyServlet
memcacheServlet
*.to
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。
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 getBean(String name, Class requiredClass){
return applicationContext.getBean(name, requiredClass);
}
} applicationContext.xml中配置一下：
在servlet中使用即可：
globalCacheService = (GlobalCacheService) SpringContextUtil.getBean("globalCacheService", GlobalCacheService.class);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。
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