AbstractServiceServlet.java

package azkaban.webapp.servlet;

import java.io.IOException;
import java.io.OutputStream;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.codehaus.jackson.map.ObjectMapper;
import azkaban.webapp.AzkabanServer;

public class AbstractServiceServlet extends HttpServlet {

  private static final long serialVersionUID = 1L;
  public static final String JSON_MIME_TYPE = "application/json";

  private AzkabanServer application;

  @Override
  public void init(ServletConfig config) throws ServletException {
    application =
        (AzkabanServer) config.getServletContext().getAttribute(
            AzkabanServletContextListener.AZKABAN_SERVLET_CONTEXT_KEY);

    if (application == null) {
      throw new IllegalStateException(
          "No batch application is defined in the servlet context!");
    }
  }

  protected void writeJSON(HttpServletResponse resp, Object obj)
      throws IOException {
    resp.setContentType(JSON_MIME_TYPE);
    ObjectMapper mapper = new ObjectMapper();
    OutputStream stream = resp.getOutputStream();
    mapper.writeValue(stream, obj);
  }

  public boolean hasParam(HttpServletRequest request, String param) {
    return request.getParameter(param) != null;
  }

  public String getParam(HttpServletRequest request, String name)
      throws ServletException {
    String p = request.getParameter(name);
    if (p == null)
      throw new ServletException("Missing required parameter '" + name + "'.");
    else
      return p;
  }

  public String getParam(HttpServletRequest request, String name,
      String defaultVal) {
    String p = request.getParameter(name);
    if (p == null) {
      return defaultVal;
    }

    return p;
  }

  public int getIntParam(HttpServletRequest request, String name)
      throws ServletException {
    String p = getParam(request, name);
    return Integer.parseInt(p);
  }

  public int getIntParam(HttpServletRequest request, String name, int defaultVal) {
    if (hasParam(request, name)) {
      try {
        return getIntParam(request, name);
      } catch (Exception e) {
        return defaultVal;
      }
    }
    return defaultVal;
  }

  public long getLongParam(HttpServletRequest request, String name)
      throws ServletException {
    String p = getParam(request, name);
    return Long.parseLong(p);
  }

  public long getLongParam(HttpServletRequest request, String name,
      long defaultVal) {
    if (hasParam(request, name)) {
      try {
        return getLongParam(request, name);
      } catch (Exception e) {
        return defaultVal;
      }
    }
    return defaultVal;
  }

}