项目中调用service层方法
使用的工具类
package com.fltd.tourism.util; import java.util.Locale; import java.util.Map; import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.stereotype.Component; @Component public class SpringContextUtil implements ApplicationContextAware { private static ApplicationContext applicationContext = null; public void setApplicationContext(ApplicationContext context) throws BeansException { applicationContext = context; } /** * 获取applicationContext对象 * * @return */ public static ApplicationContext getApplicationContext() { return applicationContext; } @SuppressWarnings("unchecked") public static <T> T getBean(String name) { return (T) applicationContext.getBean(name); } public static <T> T getBean(Class<T> clazz) { System.out.println(applicationContext); return applicationContext.getBean(clazz); } /** * 根据bean的id来查找对�? * * @param id * @return */ @SuppressWarnings("unchecked") public static <T> T getBeanById(String id) { return (T) applicationContext.getBean(id); } /** * 根据bean的class来查找对�? * * @param c * @return */ @SuppressWarnings({ "unchecked", "rawtypes" }) public static <T> T getBeanByClass(Class c) { return (T) applicationContext.getBean(c); } /** * 根据bean的class来查找所有的对象(包括子类) * * @param c * @return */ @SuppressWarnings({ "unchecked", "rawtypes" }) public static Map getBeansByClass(Class c) { return applicationContext.getBeansOfType(c); } public static String getMessage(String key) { return applicationContext.getMessage(key, null, Locale.getDefault()); } }
使用方法：
SpringContextUtil.getBean(xxxService.class).xxxmethod();
或者使用
在项目中遇到一个问题，在 Filter中注入 Serivce失败，注入的service始终为null。如下所示：
1 public class WeiXinFilter implements Filter{
2
3 @Autowired
4 private UsersService usersService;
5
6 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
7 HttpServletRequest req = (HttpServletRequest)request;
8 HttpServletResponse resp = (HttpServletResponse)response;
9 Users users = this.usersService.queryByOpenid(openid);
10 }
上面的 usersService 会报空指针异常。
解决方法一：
1 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
2 HttpServletRequest req = (HttpServletRequest)request;
3 HttpServletResponse resp = (HttpServletResponse)response;
4 ServletContext sc = req.getSession().getServletContext();
5 XmlWebApplicationContext cxt = (XmlWebApplicationContext)WebApplicationContextUtils.getWebApplicationContext(sc);
6
7 if(cxt != null && cxt.getBean("usersService") != null && usersService == null)
8 usersService = (UsersService) cxt.getBean("usersService");
9
10 Users users = this.usersService.queryByOpenid(openid);
解决方法二：
public class WeiXinFilter implements Filter{
private UsersService usersService;
public void init(FilterConfig fConfig) throws ServletException {
ServletContext sc = fConfig.getServletContext();
XmlWebApplicationContext cxt = (XmlWebApplicationContext)WebApplicationContextUtils.getWebApplicationContext(sc);
if(cxt != null && cxt.getBean("usersService") != null && usersService == null)
usersService = (UsersService) cxt.getBean("usersService");
}
相关原理：
1. 如何获取 ServletContext：
1）在javax.servlet.Filter中直接获取
ServletContext context = config.getServletContext();
2）在HttpServlet中直接获取
this.getServletContext()
3）在其他方法中，通过HttpServletRequest获得
request.getSession().getServletContext();
2. WebApplicationContext 与 ServletContext (转自：http://blessht.iteye.com/blog/2121845)：
Spring的 ContextLoaderListener是一个实现了ServletContextListener接口的监听器，在启动项目时会触发contextInitialized方法（该方法主要完成ApplicationContext对象的创建），在关闭项目时会触发contextDestroyed方法（该方法会执行ApplicationContext清理操作）。
ConextLoaderListener加载Spring上下文的过程
①启动项目时触发contextInitialized方法，该方法就做一件事：通过父类contextLoader的initWebApplicationContext方法创建Spring上下文对象。
②initWebApplicationContext方法做了三件事：创建 WebApplicationContext；加载对应的Spring文件创建里面的Bean实例；将WebApplicationContext放入 ServletContext（就是Java Web的全局变量）中。
③createWebApplicationContext创建上下文对象，支持用户自定义的上下文对象，但必须继承自ConfigurableWebApplicationContext，而Spring MVC默认使用ConfigurableWebApplicationContext作为ApplicationContext（它仅仅是一个接口）的实 现。
④configureAndRefreshWebApplicationContext方法用 于封装ApplicationContext数据并且初始化所有相关Bean对象。它会从web.xml中读取名为 contextConfigLocation的配置，这就是spring xml数据源设置，然后放到ApplicationContext中，最后调用传说中的refresh方法执行所有Java对象的创建。
⑤完成ApplicationContext创建之后就是将其放入ServletContext中，注意它存储的key值常量。
解决方法三：
直接使用spring mvc中的HandlerInterceptor或者HandlerInterceptorAdapter 来替换Filter:
public class WeiXinInterceptor implements HandlerInterceptor {
@Autowired
private UsersService usersService;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
// TODO Auto-generated method stub
return false;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
throws Exception {
// TODO Auto-generated method stub
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
// TODO Auto-generated method stub
}
}
配置拦截路径：
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**" />
<bean class="net.xxxx.interceptor.WeiXinInterceptor" />
</mvc:interceptor>
</mvc:interceptors>
Filter 中注入 Service 的示例：
1 public class WeiXinFilter implements Filter{
2 private UsersService usersService;
3 public void init(FilterConfig fConfig) throws ServletException {}
4 public WeiXinFilter() {}
5 public void destroy() {}
6
7 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
8 HttpServletRequest req = (HttpServletRequest)request;
9 HttpServletResponse resp = (HttpServletResponse)response;
10
11 String userAgent = req.getHeader("user-agent");
12 if(userAgent != null && userAgent.toLowerCase().indexOf("micromessenger") != -1){ // 微信浏览器
13 String servletPath = req.getServletPath();
14 String requestURL = req.getRequestURL().toString();
15 String queryString = req.getQueryString();
16
17 if(queryString != null){
18 if(requestURL.indexOf("mtzs.html") !=-1 && queryString.indexOf("LLFlag")!=-1){
19 req.getSession().setAttribute("LLFlag", "1");
20 chain.doFilter(request, response);
21 return;
22 }
23 }
24
25 String openidDES = CookieUtil.getValueByName("openid", req);
26 String openid = null;
27 if(StringUtils.isNotBlank(openidDES)){
28 try {
29 openid = DesUtil.decrypt(openidDES, "rxxxxxxxxxde"); // 解密获得openid
30 } catch (Exception e) {
31 e.printStackTrace();
32 }
33 }
34 // ... ...
35 String[] pathArray = {"/weixin/enterAppFromWeiXin.json", "/weixin/getWeiXinUserInfo.json",
36 "/weixin/getAccessTokenAndOpenid.json", "/sendRegCode.json", "/register.json",
37 "/login.json", "/logon.json", "/dump.json", "/queryInfo.json"};
38 List<String> pathList = Arrays.asList(pathArray);
39
40 String loginSuccessUrl = req.getParameter("path");
41 String fullLoginSuccessUrl = "http://www.axxxxxxx.cn/pc/";
42 if(requestURL.indexOf("weixin_gate.html") != -1){
43 req.getSession().setAttribute("loginSuccessUrl", loginSuccessUrl);
44 // ... ...
45 }
46 ServletContext sc = req.getSession().getServletContext();
47 XmlWebApplicationContext cxt = (XmlWebApplicationContext)WebApplicationContextUtils.getWebApplicationContext(sc);
48
49 if(cxt != null && cxt.getBean("usersService") != null && usersService == null)
50 usersService = (UsersService) cxt.getBean("usersService");
51
52 Users users = this.usersService.queryByOpenid(openid);
53 // ... ...
54 if(pathList.contains(servletPath)){ // pathList 中的访问路径直接 pass
55 chain.doFilter(request, response);
56 return;
57 }else{
58 if(req.getSession().getAttribute(CommonConstants.SESSION_KEY_USER) == null){ // 未登录
59 String llFlag = (String) req.getSession().getAttribute("LLFlag");
60 if(llFlag != null && llFlag.equals("1")){ // 处理游客浏览
61 chain.doFilter(request, response);
62 return;
63 }
64 // ... ...// 3. 从腾讯服务器去获得微信的 openid ,
65 req.getRequestDispatcher("/weixin_gate.html").forward(request, response);
66 return;
67 }else{ // 已经登录
68 // 4. 已经登录时的处理
69 chain.doFilter(request, response);
70 return;
71 }
72 }
73 }else{ // 非微信浏览器
74 chain.doFilter(request, response);
75 }
76 }
77
78 }
