如何将两个值传递给Java servlet？

Question

I am developing a JSF application which has a servlet to display binary images. I have it working with one parameter but wanted to pass two parameters. It only seems to get the first parameter. My mapping looks like this.

<servlet>
    <servlet-name>imageServlet</servlet-name>
    <servlet-class>com.myapp.system.ImageServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>imageServlet</servlet-name>
    <url-pattern>/image/*</url-pattern>
</servlet-mapping>

When I call the servlet it looks like this

<p:graphicImage value="image?app=avatar?id=#{bean.imgId}" />

In my servlet I get the parameters like so

 String id = request.getParameter("id");
 String app = request.getParameter("app");

If I output the app string it displays this

 avatar?id=166

How can I allow the servlet url-patter to take in two values and be able to parse them using the getParameter method. Thanks.

Answer 1

The JSP tag should be written as:

<p:graphicImage value="image?app=avatar&amp;id=#{bean.imgId}" />

Parameters in the query part of a URL should be separated by '&'s not '?'s.

(You can ignore this, but them you won't be able to use ServletRequest.getParameter(String) to retrieve the parameter values. Instead you'll have to use ServletRequest.getQueryString() and parse the individual parameters yourself.)

Answer 2

用于编码URL参数的格式是键-值对与符号（分离& ）：

<p:graphicImage value="image?app=avatar&id=#{bean.imgId}" />

Answer 3

除第一个参数外，在所有参数之前使用与号：

<p:graphicImage value="image?app=avatar&id=#{bean.imgId}" />

Answer 4

<p:graphicImage value="image?app=avatar&id=#{bean.imgId}" />

＆而不是第二个？