servlet-utils

Provides utility classes for working with servlets. Below are some examples; for a full list, see the API.

Init parameter reading

Package com.github.robtimus.servlet.parameters contains several classes that make it easy to read init parameters. For instance, to read an int init parameter that cannot be negative:

requestLimit = IntParameter.of(config, "requestLimit")
        .atLeast(0)
        .valueWithDefault(Integer.MAX_VALUE);

Transforming input/output

Sometimes it's necessary to transform the input and/or output. Class ServletUtils contains methods to transform a ServletInputStream, ServletOutputStream, BufferedReader or PrintWriter, as retrieved from a ServletRequest or ServletResponse.

In addition, classes InputTransformingHttpServletRequestWrapper and OutputTransformingHttpServletResponseWrapper make it easy to wrap an HttpServletRequest or HttpServletResponse with transforming input or output. Simply override the necessary transform method to provide the actual transformation.

Cookie reading

Class CookieUtils contains methods to read cookies as optionals and streams.

Asynchronous support for try-finally

Method AsyncUtils.doFilter can be used as a replacement for a try-finally block that also works with asynchronous request handling.

The following only works for non-asynchronous request handling; for asynchronous request handling the code in the finally block is often executed too early.

try {
    chain.doFilter(request, response);
} finally {
    doSomething(request, response);
}

The following works both with asynchronous and non-asynchronous request handling.

AsyncUtils.doFilter(request, response, chain, (req, res) -> {
    doSomething(req, res);
});

Body capturing filter

Class BodyCapturingFilter can be used as base class for a filter that captures the request and response bodies. It captures the request body while it body is read, and provides callback methods to perform the necessary logic when the request body is read or when the response body is written. See its documentation for more details.