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Struts2 -- 获取Servlet API
在struts2中获取Servlet API有三种方式：
1.通过ActionContext来获取
1.获取一个ActionContext对象。
ActionContext context=ActionContext.getContext();
2.获取servlet api
注意:通过ActionContext获取的不是真正的Servlet API,而是一个Map集合。
1.context.getApplication()
2.context.getSession()
3.context.getParameter();---得到的就相当于request.getParameterMap()
4.context.put(String,Object) 相当于request.setAttribute(String,String);
public class Demo01Action extends ActionSupport{ @Override public String execute() throws Exception { ActionContext context = ActionContext.getContext(); Map<String, Object> application = context.getApplication(); Map<String, Object> session = context.getSession(); Map<String, Object> parameters = context.getParameters(); context.put(key, value); return null; }}
2.注入方式获取(这种方式是真正的获取到了Servlet API)
1.要求action类必须实现提定接口。
ServletContextAware ： 注入ServletContext对象
ServletRequestAware ：注入 request对象
ServletResponseAware ： 注入response对象
2.重定接口中的方法。
private HttpServletRequest request;
3.声明一个web对象，使用接口中的方法的参数对声明的web对象赋值.
public void setServletRequest(HttpServletRequest request) {
this.request = request;
}
public class Demo01Action extends ActionSupport implements ServletContextAware, ServletRequestAware, ServletResponseAware { private ServletContext context; private HttpServletRequest request; private HttpServletResponse response; @Override public String execute() throws Exception { return null; } @Override public void setServletContext(ServletContext context) { this.context = context; } @Override public void setServletRequest(HttpServletRequest request) { this.request = request; } @Override public void setServletResponse(HttpServletResponse response) { this.response = response; }}
扩展:分析其实现：
是使用struts2中的一个interceptor完成的.
<interceptor name="servletConfig" class="org.apache.struts2.interceptor.ServletConfigInterceptor"/>
源码:
public class ServletConfigInterceptor extends AbstractInterceptor implements StrutsStatics { private static final long serialVersionUID = 605261777858676638L; /** * Sets action properties based on the interfaces an action implements. Things like application properties, * parameters, session attributes, etc are set based on the implementing interface. * * @param invocation an encapsulation of the action execution state. * @throws Exception if an error occurs when setting action properties. */ public String intercept(ActionInvocation invocation) throws Exception { final Object action = invocation.getAction(); final ActionContext context = invocation.getInvocationContext(); //判断当前的action是否继承指定方法 if (action instanceof ServletRequestAware) {
//获取reqeust对象，并将request对象封装到action中 HttpServletRequest request = (HttpServletRequest) context.get(HTTP_REQUEST); ((ServletRequestAware) action).setServletRequest(request); } if (action instanceof ServletResponseAware) { HttpServletResponse response = (HttpServletResponse) context.get(HTTP_RESPONSE); ((ServletResponseAware) action).setServletResponse(response); } if (action instanceof ParameterAware) { ((ParameterAware) action).setParameters((Map)context.getParameters()); } if (action instanceof ApplicationAware) { ((ApplicationAware) action).setApplication(context.getApplication()); } if (action instanceof SessionAware) { ((SessionAware) action).setSession(context.getSession()); } if (action instanceof RequestAware) { ((RequestAware) action).setRequest((Map) context.get("request")); } if (action instanceof PrincipalAware) { HttpServletRequest request = (HttpServletRequest) context.get(HTTP_REQUEST); if(request != null) { // We are in servtlet environment, so principal information resides in HttpServletRequest ((PrincipalAware) action).setPrincipalProxy(new ServletPrincipalProxy(request)); } } if (action instanceof ServletContextAware) { ServletContext servletContext = (ServletContext) context.get(SERVLET_CONTEXT); ((ServletContextAware) action).setServletContext(servletContext); } return invocation.invoke(); }}
3.通过ServletActionContext获取.
在ServletActionContext中方法都是static。
getRequest();
getResposne();
getPageContext();
public class Demo01Action extends ActionSupport { @Override public String execute() throws Exception { HttpServletRequest request = ServletActionContext.getRequest(); HttpServletResponse response = ServletActionContext.getResponse(); PageContext pageContext = ServletActionContext.getPageContext(); ServletContext servletContext = ServletActionContext.getServletContext(); return null; }}
Struts2 -- 获取Servlet API