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/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.qpid.management.web.action;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;
import java.util.Properties;
import java.util.Map.Entry;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanInfo;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* This controller is responsible to provide a jmx perspective of a specific resource.
* That means that this controller is querying the Platform MBean server in order to
* get metadata for the requested mbean.
*
* After that metadata will be forwarded to the appropriate view page and therefore
* will be shown on the Admin console.
*
* @author Andrea Gazzarini
*/
public class JmxPerspectiveAction extends HttpServlet
{
private static final long serialVersionUID = -2411413147821629363L;
/**
* Adapter interface for converting objects on html strings.
*
* @author Andrea Gazzarini.
*/
interface JavaToHtmlAdapter
{
/**
* Returns an HTML string representation of the given object.
*
* @param javaObject the object that needs to be converted.
* @return an html string containing value of the given object.
*/
String toHtml(Object javaObject);
}
/**
* Adapter implementation for Map (and subclasses).
*/
private JavaToHtmlAdapter mapAdapter = new JavaToHtmlAdapter()
{
@SuppressWarnings("unchecked")
public String toHtml(Object javaObject)
{
Map<String,Object> value = (Map<String, Object>) javaObject;
// Sanity check : if the map is empty or null there's no need to
// do any convertion
if (value == null || value.isEmpty())
{
return "(empty)";
}
StringBuilder builder = new StringBuilder("<ul>");
for (Entry<String, Object> entry : value.entrySet())
{
builder
.append("<li>")
.append(entry.getKey())
.append(" = ")
.append(entry.getValue());
}
builder.append("</ul>");
return builder.toString();
}
};
private Map<String, JavaToHtmlAdapter> _adapters = new HashMap<String, JavaToHtmlAdapter>();
@Override
public void init() throws ServletException
{
_adapters.put(Map.class.getName(), mapAdapter);
_adapters.put(HashMap.class.getName(),mapAdapter);
_adapters.put(Properties.class.getName(),mapAdapter);
_adapters.put(Hashtable.class.getName(),mapAdapter);
}
@SuppressWarnings("unchecked")
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
String resourceId = null;
try
{
resourceId = request.getParameter("resourceId");
ObjectName objectName = new ObjectName(resourceId);
String [] keyProperties = objectName.getKeyPropertyListString().split(",");
MBeanServer server = ManagementFactory.getPlatformMBeanServer();
MBeanInfo metadata = server.getMBeanInfo(objectName);
Map<String, String> attributes = getAttributes(server, objectName,metadata.getAttributes());
request.setAttribute("resourceId", objectName);
request.setAttribute("metadata",metadata);
request.setAttribute("nameAttributes",keyProperties);
request.setAttribute("attributes",attributes);
RequestDispatcher dispatcher = request.getRequestDispatcher("/jmx_perspective.jsp");
dispatcher.forward(request,response);
} catch(MalformedObjectNameException exception)
{
request.setAttribute("errorMessage","Malformed Resource ID : supplied value is "+resourceId);
request.setAttribute("exception",exception);
RequestDispatcher dispatcher = request.getRequestDispatcher("/error_page.jsp");
dispatcher.forward(request,response);
}
catch(Exception exception)
{
request.setAttribute("errorMessage","Unable to detect the exact cause Please look at the reported stack trace below.");
request.setAttribute("exception",exception);
RequestDispatcher dispatcher = request.getRequestDispatcher("/error_page.jsp");
dispatcher.forward(request,response);
}
}
/**
* Starting from an mbean metadata, this method retrieves all the attributes
* from the corresponding MBean Server.
*
* @param server the mbean server where the target mbean is registered.
* @param name the name of the target mbean.
* @param metadata the metadata of mbean.
* @return a map containing all attributes of the given mbean.
* @throws Exception when it's not possible to retrieve attributes.
*/
private Map<String, String> getAttributes(MBeanServer server, ObjectName name, MBeanAttributeInfo [] metadata) throws Exception
{
Map<String,String> result = new HashMap<String, String>(metadata.length);
for (MBeanAttributeInfo attribute : metadata)
{
Object value = server.getAttribute(name, attribute.getName());
result.put(attribute.getName(),getAdaptedValue(attribute.getType(), value));
}
return result;
}
/**
* Converts the given attribute value in a html string format.
*
* @param type the java type of the given attribute value.
* @param value the attribute value.
* @return a html string format of the given value.
*/
private String getAdaptedValue(String type, Object value)
{
JavaToHtmlAdapter adapter = _adapters.get(type);
return (adapter != null) ? adapter.toHtml(value) : String.valueOf(value);
}
}
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