将请求URL更改为指向servlet过滤器中的不同Web服务器

Question

Is there any way to change the request URL to point to another page hosted in different web server? Suppose I have a page hosted in Tomcat:

<form action="http://localhost:8080/Test/dummy.jsp" method="Post">
    <input type="text" name="text"></input>
    <input type="Submit" value="submit"/>
</form>

And I intercept the request using a servlet filter:

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException,ServletException {
    HttpServletRequest request = (HttpServletRequest) req;
    chain.doFilter(req, res);
    return;
}

What I want is to change the request URL to point to a PHP page hosted in another web server http://localhost/display.php. I know that I can use response.sendRedirect, but it won't work in my case because it discards all POST data. Is there any way to change the request URL so that chain.doFilter(req, res); will forward me to that PHP page?

Answer 1

The HttpServletResponse#sendRedirect() sends by default a HTTP 302 redirect which indeed implicitly creates a new GET request.

You need a HTTP 307 redirect instead.

response.setStatus(307);
response.setHeader("Location", "http://localhost/display.php");

(I assume that the http://localhost URL is just exemplary; this obviously won't work in production)

Note: browsers will ask for confirmation before continuing.

An alternative would be to play for proxy:

URLConnection connection = new URL("http://localhost/display.php").openConnection();
connection.setDoOutput(true); // POST
// Copy headers if necessary.

InputStream input1 = request.getInputStream();
OutputStream output1 = connection.getOutputStream();
// Copy request body from input1 to output1.

InputStream input2 = connection.getInputStream();
OutputStream output2 = response.getOutputStream();
// Copy response body from input2 to output2.

Note: you'd better use a servlet for this instead of a filter.

Again another alternative would be to just port PHP code to JSP/Servlet code. Again another alternative would be to run PHP straight on Tomcat via a PHP module such as Quercus.