今天又學得了如何用攔截器攔截ajax，原來是異步的原因，所以要用不同的處理方法。之前用普通的攔截器，出現的現象就是跟沒用攔截器時的一樣。
首先要明白：
普通請求與ajax請求的報文頭不一樣，通過如下
-
String requestType = request.getHeader("X-Requested-With");
-
如果requestType能拿到值，並且值爲XMLHttpRequest,表示客戶端的請求爲異步請求，那自然是ajax請求了，反之如果爲null,則是普通的請求
以下是驗證登陸的攔截器，代碼如下：
package com.bossin.vote.interceptor;
import java.io.PrintWriter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class VoteInterceptor implements Interceptor {
private static final long serialVersionUID = 1L;
public void destroy() {
}
public void init() {
}
public String intercept(ActionInvocation invocation) throws Exception {
HttpServletRequest req = ServletActionContext.getRequest();
if(req.getSession().getAttribute("login_account")==null){
HttpServletResponse response = ServletActionContext.getResponse();
PrintWriter pw = response.getWriter();
String flag = "";
if (req.getHeader("X-Requested-With") != null
&& req.getHeader("X-Requested-With").equalsIgnoreCase(
"XMLHttpRequest")) {
response.setCharacterEncoding("text/html;charset=utf-8");
response.setContentType("text/html;charset=utf-8");
flag = "請先登錄";
pw.write(flag);
return null;
}
}
return invocation.invoke();
}
}
struts.xml 配置跟普通的攔截器就是少了返回頁面的設置，具體 配置如下：
<package name="vote" extends="struts-default">
<!-- 攔截器 -->
<interceptors>
<!-- 登錄驗證 -->
<interceptor name="VoteInterceptor" class="com.bossin.vote.interceptor.VoteInterceptor"></interceptor>
<interceptor-stack name="verify">
<interceptor-ref name="defaultStack"></interceptor-ref>
<interceptor-ref name="VoteInterceptor"></interceptor-ref>
</interceptor-stack>
</interceptors>
<default-interceptor-ref name="verify"></default-interceptor-ref>
<action name="vote" class="com.bossin.vote.action.VoteAction" method="execute"> </action>
</package>
按上面的代碼是可以實現功能的，但會出現前臺彈出的窗口出現中文亂碼。
個人做以下處理便解決了中文亂碼：即把編碼設置放在 PrintWriter pw = response.getWriter();前面
package com.bossin.vote.interceptor;
import java.io.PrintWriter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class VoteInterceptor implements Interceptor {
private static final long serialVersionUID = 1L;
public void destroy() {
}
public void init() {
}
public String intercept(ActionInvocation invocation) throws Exception {
HttpServletRequest req = ServletActionContext.getRequest();
if(req.getSession().getAttribute("login_account")==null){
HttpServletResponse response = ServletActionContext.getResponse();
if (req.getHeader("X-Requested-With") != null
&& req.getHeader("X-Requested-With").equalsIgnoreCase(
"XMLHttpRequest")) {
response.setCharacterEncoding("text/html;charset=utf-8");
response.setContentType("text/html;charset=utf-8"); //這兩句得放在pw前，否則出現亂碼
PrintWriter pw = response.getWriter();
String flag = "請先登錄";
pw.write(flag);
return null;
}
}
return invocation.invoke();
}
}
