好的做法是使用Servlet过滤器将请求对象包装在另一个对象中。由于HttpServletRequest是一个接口,因此您可以编写自己的实现。您的实现可以保留收到的请求,并将其任何和所有方法委托给原始请求对象,还可以根据需要修改返回值。因此,您的getParameter()等方法可以在原始请求对象上调用相同的方法,并在返回之前按您认为合适的方式修改结果。
class MyHttpServletRequestWrapper implements HttpServletRequest {
private HttpServletRequest originalRequest;
public MyHttpServletRequestWrapper(HttpServletRequest originalRequest) {
this.originalRequest = originalRequest;
public String getAuthType() {return originalRequest.getAuthType();}
public String getQueryString() {return originalRequest.getQueryString();}
// etc.
public Map getParameterMap() {
Map params = originalRequest.getParameterMap();
params.remove("parameter-to-remove");
params.put("parameter-to-add", "<a value>");
//etc.
}
}
您的Servlet过滤器:
class MyFilter implements Filter {
public void init(FilterConfig config) {
// perhaps you might want to initialize something here
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
HttpServletRequest originalRequest = (HttpServletRequest) request;
HttpServletRequest newRequest = new MyHttpServletRequest(originalRequest);
chain.doFilter(newRequest, response);
}
}
您还可以继承javax.servlet.request.HttpServletRequestWrapper的子类,这将节省大量工作。