Struts 2笔记：与Servlet耦合及动态方法调用

xue_dong5437 2011-04-29

展开全文

一、与Servlet耦合

在Struts 2的Action类里，有三种方式与Servlet进行耦合。

* ActionContext与Servlet耦合，但是它无法获得HttpServletResponse
  在Action类中，ActionContext.getContext().put("hello","hello");
  在页面上可以接收，${requestScope.hello}
* Aware方式（包括ServletRequestAware,ServletResponseAware）也可以与Servlet耦合
  建议使用ActionContext
* ServletActionContext方式也可以与Servlet耦合，这个类继承自ActionContext

1.LoginAction.java

package action;

import java.util.Map;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;
import org.apache.struts2.interceptor.ServletRequestAware;
import org.apache.struts2.interceptor.ServletResponseAware;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport implements ServletRequestAware,ServletResponseAware {

private static final long serialVersionUID = 1L;

private String username;

private String password;

private HttpServletRequest httpServletRequest;

private HttpServletResponse httpServletResponse;

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
  this.password = password;
}

@SuppressWarnings("unchecked")
public String execute() throws Exception {
  if(!"admin".equals(username) || !"admin".equals(password)) {
   addFieldError("username", "用户名或密码错误！");
   return "failure";
  }
  else {

   Map map = ActionContext.getContext().getSession();
   ActionContext.getContext().put("ActionContext", "ActionContext方式耦合");
   map.put("user", "invalid");



   httpServletRequest.setAttribute("Aware", "Aware方式耦合");

   Cookie cookie = new Cookie("username", this.getUsername());
   //设置cookie最大存活时间
   //如果设置为正数，就是相应的存活时间；如果设置为负数，当浏览器被关闭的是，cookie就会被删除
   cookie.setMaxAge(1000);
   //第一次执行，cookie不会显示
   httpServletResponse.addCookie(cookie);



   HttpServletRequest request = ServletActionContext.getRequest();
   request.setAttribute("ServletActionContext", "ServletActionContext方式耦合");

   return "success";
  }
}

public void validate() {
  if(null == username || "".equals(username)) {
   addFieldError("username", "请填写用户名！");
  }
  if(null == password || "".equals(password)) {
   addFieldError("password", "请填写密码！");
  }
}

@SuppressWarnings("unchecked")
public String login() throws Exception {
  if(!"admin".equals(username) || !"admin".equals(password)) {
   addFieldError("username", "用户名或密码错误！");
   return "failure";
  }
  else {

   Map map = ActionContext.getContext().getSession();
   ActionContext.getContext().put("ActionContext", "ActionContext方式耦合");
   map.put("user", "invalid");



   httpServletRequest.setAttribute("Aware", "Aware方式耦合");

   Cookie cookie = new Cookie("username", this.getUsername());
   //设置cookie最大存活时间
   //如果设置为正数，就是相应的存活时间；如果设置为负数，当浏览器被关闭的是，cookie就会被删除
   cookie.setMaxAge(1000);
   //第一次执行，cookie不会显示
   httpServletResponse.addCookie(cookie);



   HttpServletRequest request = ServletActionContext.getRequest();
   request.setAttribute("ServletActionContext", "ServletActionContext方式耦合");

   return "success";
  }
}

//这个方法被自动执行，是依赖注入
//这是使用servlet的方法
@Override
public void setServletRequest(HttpServletRequest httpServletRequest) {
// TODO Auto-generated method stub
this.httpServletRequest = httpServletRequest;
}

@Override
public void setServletResponse(HttpServletResponse httpServletResponse) {
// TODO Auto-generated method stub
this.httpServletResponse = httpServletResponse;
}

}

这里，三种方式同时使用。在实际开发中，建议使用ActionContext和ServletActionContext

2.result.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www./TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
用户名：${requestScope.username } 
密码：${requestScope.password } 
ActionContext方式耦合：${requestScope.ActionContext } 
Aware方式耦合：${requestScope.Aware } 
Cookie（Aware方式耦合）：${cookie.username.value } 
ServletActionContext方式耦合：${requestScope.ServletActionContext }
</body>
</html>

运行结果：

二、动态方法调用 dynamic method invocation