improve handling of startup error handling

scm-webapp/src/main/java/sonia/scm/template/ErrorServlet.java

@@ -0,0 +1,165 @@
+/**
+ * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.template;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.base.Throwables;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+import sonia.scm.SCMContextProvider;
+import sonia.scm.util.IOUtil;
+import sonia.scm.util.Util;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ */
+@Singleton
+public class ErrorServlet extends HttpServlet
+{
+
+  /** Field description */
+  private static final long serialVersionUID = -3289076078469757874L;
+
+  //~--- constructors ---------------------------------------------------------
+
+  /**
+   * Constructs ...
+   *
+   *
+   * @param context
+   * @param handler
+   */
+  @Inject
+  public ErrorServlet(SCMContextProvider context, TemplateHandler handler)
+  {
+    this.context = context;
+    this.handler = handler;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param request
+   * @param response
+   *
+   * @throws IOException
+   * @throws ServletException
+   */
+  @Override
+  protected void doGet(HttpServletRequest request, HttpServletResponse response)
+          throws ServletException, IOException
+  {
+    processRequest(request, response);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param request
+   * @param response
+   *
+   * @throws IOException
+   * @throws ServletException
+   */
+  @Override
+  protected void doPost(HttpServletRequest request,
+                        HttpServletResponse response)
+          throws ServletException, IOException
+  {
+    processRequest(request, response);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param request
+   * @param response
+   *
+   * @throws IOException
+   * @throws ServletException
+   */
+  private void processRequest(HttpServletRequest request,
+                              HttpServletResponse response)
+          throws ServletException, IOException
+  {
+    PrintWriter writer = null;
+
+    try
+    {
+      writer = response.getWriter();
+
+      Map<String, Object> env = new HashMap<String, Object>();
+      String error = Util.EMPTY_STRING;
+
+      if (context.getStartupError() != null)
+      {
+        error = Throwables.getStackTraceAsString(context.getStartupError());
+      }
+
+      env.put("error", error);
+      handler.render("/error.html", writer, env);
+    }
+    finally
+    {
+      IOUtil.close(context);
+    }
+  }
+
+  //~--- fields ---------------------------------------------------------------
+
+  /** Field description */
+  private SCMContextProvider context;
+
+  /** Field description */
+  private TemplateHandler handler;
+}