Skeleton for an easesolutions codestyle Servlet file

SkeletonServlet.java

package com.easesolutions.jira.plugin.mailclient.servlet;

import com.atlassian.jira.user.util.UserManager;
import com.atlassian.plugin.webresource.UrlMode;
import com.atlassian.plugin.webresource.WebResourceUrlProvider;
import com.atlassian.sal.api.auth.LoginUriProvider;
import com.atlassian.templaterenderer.TemplateRenderer;
import com.easesolutions.jira.plugin.mailclient.model.service.PermissionAccessService;
import com.easesolutions.jira.plugin.mailclient.util.LoggerHelper;
import com.easesolutions.jira.plugin.mailclient.util.ProjectPartsHelper;
import com.easesolutions.jira.plugin.mailclient.util.ServletHelper;
import com.easesolutions.jira.plugin.mailclient.util.UrlHelper;
import com.google.gson.Gson;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;

public class AdminRulesServlet extends BaseServlet
{
  private static final long serialVersionUID = 0x0008;

  private final LoggerHelper _loggerHelper;
  private final PermissionAccessService _permissionAccess;
  private final WebResourceUrlProvider _webResource;
  private final Gson _gson;

  //dependency injection ceremony
  public AdminRulesServlet(
    TemplateRenderer engine,
    UserManager jiraUserManager,
    com.atlassian.sal.api.user.UserManager userManager,
    LoginUriProvider loginUriProvider,
    UrlHelper urlHelper,
    PermissionAccessService permissionAccessService,
    WebResourceUrlProvider webResource
  ) {
    super(engine, jiraUserManager, userManager, loginUriProvider, urlHelper);
    this._permissionAccess = permissionAccessService;
    this._webResource = webResource;
    this._loggerHelper = new LoggerHelper(AdminRulesServlet.class);
    this._gson = new Gson();
  }

  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    _loggerHelper.start("doGet");
    _loggerHelper.param(req, resp);
    ServletHelper.CheckResult check;

    //extract user from request
    check = performInitialCheck(req, resp);
    if(check==null) {
      return;
    }

    //request mapping to specific functions
    String op;
    op = req.getParameter("op");
    if (op != null) {
      if (op.equals("mygetoperation")) {
        handleMyGetOperation(check, resp);
      }
    } else {
      handleDefaultContent(check, resp);
    }
    _loggerHelper.end("doGet");
  }

  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    _loggerHelper.start("doPost");
    _loggerHelper.param(req, resp);
    ServletHelper.CheckResult check;

    //extract user from request
    check = performInitialCheck(req, resp);
    if(check==null) {
      return;
    }

    //request mapping to specific functions
    String op;
    op = req.getParameter("op");
    if (op != null) {
      if (op.equals("mypostoperation")) {
        handleMyPostOperation(check, resp, req);
      }
    } else {
      ServletHelper.sendBadRequest(resp);
    }
    _loggerHelper.end("doPost");
  }

  private void handleDefaultContent(ServletHelper.CheckResult check, HttpServletResponse resp) throws IOException {
    _loggerHelper.start("handleDefaultContent");
    _loggerHelper.param(check, resp);
    String rsrc = _webResource.getStaticPluginResourceUrl("com.easesolutions.jira.plugins.my-plugin:my.js.resources", "", UrlMode.ABSOLUTE);
    HashMap<String, Object> model = new HashMap<String, Object>();

    //if another HTML / CSS part should be included in the initial template, add it like this to the context.
    model.put("myTemplatePart", ProjectPartsHelper.createPart(_engine, null, new HashMap<String, Object>(), rsrc, "/templates/templatePart.vm"));
    model.put("rsrc_url", rsrc);

    ServletHelper.addHtmlResponseType(resp);

    //respond with the compiled .vm template
    _engine.render("templates/template.vm", model, resp.getWriter());
    _loggerHelper.end("handleDefaultContent");
  }

  private void handleMyGetOperation(ServletHelper.CheckResult check, HttpServletResponse resp) throws IOException {
    _loggerHelper.start("handleMyGetOperation");
    _loggerHelper.param(check, resp);
    try {

      if (!_permissionAccess.hasAccess(check.appUser, PermissionAccessService.Access.MY_PERMISSION_READ)) {
        throw new ServletHelper.BadData();
      }

      //creating an object to return as json to the client
      MyJsonData result = new MyJsonData();
      result.myInteger = 42;
      result.myString = "my new string";

      //converting the java object to JSON and returning it
      ServletHelper.writeJsonBody(resp, _gson.toJson(result));
    } catch (Exception e) {
      _loggerHelper.error(e);
      ServletHelper.sendBadRequest(resp);
    } finally {
      _loggerHelper.end("handleMyGetOperation");
    }
  }

  private void handleMyPostOperation(ServletHelper.CheckResult check, HttpServletResponse resp, HttpServletRequest req) throws IOException {
    _loggerHelper.start("handleMyPostOperation");
    _loggerHelper.param(check, resp);
    try {

      //permission check
      if (!_permissionAccess.hasAccess(check.appUser, PermissionAccessService.Access.MY_PERMISSION_WRITE)) {
        throw new ServletHelper.BadData();
      }

      //convert JSON to Java object
      MyJsonData payload = _gson.fromJson(ServletHelper.readJsonBody(req).toString(), MyJsonData.class);
      //do whatever you want with the posted data
      System.out.println(payload);

      ServletHelper.sendSuccess(resp);
    } catch (Exception e) {
      _loggerHelper.error(e);
      ServletHelper.sendBadRequest(resp);
    } finally {
      _loggerHelper.end("handleMyPostOperation");
    }
  }

  //payload java class
  private class MyJsonData {

    public Integer myInteger;
    public String myString;

  }

}