关于网友提出的“ 删除cookie为什么得到的是"null"”问题疑问，本网通过在网上对“ 删除cookie为什么得到的是"null"”有关的相关答案进行了整理，供用户进行参考，详细问题解答如下：
问题： 删除cookie为什么得到的是"null"
描述: 创建cookie
public class TestCookie extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
Cookie cookie = new Cookie("color","red");
cookie.setMaxAge(10);
response.addCookie(cookie);
out.print("cookie已创建");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
删除cookie
public class DeleteCookie extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
Cookie[] cookies = request.getCookies();
for(Cookie cookie : cookies){
if(cookie.getName().equalsIgnoreCase("color")){
cookie.setValue(null);
response.addCookie(cookie);
out.print("已删除");
break;
}
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
检查cookie
public class TestCookie2 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
String color = null;
Cookie[] cookies = request.getCookies();
if(cookies != null){
for(Cookie cookie:cookies){
if(cookie.getName().equalsIgnoreCase("color")){
color = cookie.getValue();
}
}
}
out.println(color);
out.println("null".equals(color));
//DeleteCookie删除cookie的时候设置color的值是null，删除后为什么color得到的值是"null"字符串? }
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
解决方案1:本帖最后由 java2000_net 于 2011-06-21 15:45:42 编辑
打开 fiddler 等http调试工具，自己看看吧。
以上介绍了“ 删除cookie为什么得到的是"null"”的问题解答，希望对有需要的网友有所帮助。
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