Jersey AbstractParam

AbstractParam.java

package com.proofpoint.anomalytics.mailfetcher;

import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Response;

import static javax.ws.rs.core.Response.Status;

/**
 * Abstract parameter class for Jersey parameters
 *
 * @param <T> parameter value type
 * @see <a href="http://codahale.com/what-makes-jersey-interesting-parameter-classes/">
 *      http://codahale.com/what-makes-jersey-interesting-parameter-classes/</a>
 */
public abstract class AbstractParam<T>
{
    private final T value;
    private final String originalParam;

    public AbstractParam(String param)
            throws WebApplicationException
    {
        this.originalParam = param;
        try {
            this.value = parse(param);
        }
        catch (Throwable e) {
            throw new WebApplicationException(onError(param, e));
        }
    }

    public T getValue()
    {
        return value;
    }

    public String getOriginalParam()
    {
        return originalParam;
    }

    @Override
    public String toString()
    {
        return value.toString();
    }

    protected abstract T parse(String param)
            throws Throwable;

    protected Response onError(String param, Throwable e)
    {
        return Response
                .status(Status.BAD_REQUEST)
                .entity(getErrorMessage(param, e))
                .build();
    }

    protected String getErrorMessage(String param, Throwable e)
    {
        return "Invalid parameter: " + param + " (" + e.getMessage() + ")";
    }
}