Question

如何在过滤器Filter.java中获取jsp页面文本框的值?

Answer 1

1、在Jsp页面将文本框输入域放在html表单form之中提交
2、后台定义一个过滤器继承Filter.java
3、在过滤器中的doFilter方法中，将参数ServletRequest转化为HttpServletRequest
4、利用HttpServletRequest.getParameter();方法即可获取对应输入域的value值。
示例：
在Jsp页面:
<form>
<input type="text" name="username" value="zhangsan"/>

</form>
后台过滤器：
public class TestFilter implements Filter{

@Override
public void destroy() {
}

@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain filter) throws IOException, ServletException {
HttpServletRequest res = (HttpServletRequest) request;
//获取页面的username输入框的值

String username = request.getParameter("username");

return;
}

@Override
public void init(FilterConfig arg0) throws ServletException {

}
}

Answer 2

楼上的说的对但不详细，这是源码，其实就是进行一下类型转换！
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {
// TODO Auto-generated method stub
//请求的强制转换
HttpServletRequest request=(HttpServletRequest)arg0;
//响应的强制转换
HttpServletResponse response=(HttpServletResponse)arg1;
//转换完后就像在Servlet中的获取方式相同了
//例： String str=request.getParameters("xxx");
}

Answer 3

过滤器也是继承于servlet 可通过表单提交方式，或url传值 ,拿到文本框的值
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
System.out.println("登录检查过滤器开始工作。。。");
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
不过要将 ServletRequest 强制转换为 HttpServletRequest才可以拿到提交过来的值。。

Answer 4

HttpServletRequest request = (HttpServletRequest) req

String x=req.getParameters("xxx");