com.cedarsoftware.util.UrlInvocationHandler Maven / Gradle / Ivy
package com.cedarsoftware.util;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.HttpURLConnection;
/**
* Useful utility for allowing Java code to make Ajax calls, yet the Java code
* can make these calls via Dynamic Proxies created from Java interfaces for
* the remote server(s).
*
* Example:
*
* Assume you have a tomcat instance running a JSON Command Servlet, like com.cedarsoftware's or
* Spring MVC.
*
* Assume you have a Java interface 'Explorer' that is mapped to a Java bean that you are allowing
* to be called through RESTful JSON calls (Ajax / XHR).
*
* Explorer has methods on it, like getFiles(userId), etc.
*
* You need to use a SessionAware (JSESSIONID only) or CookieAware UrlInvocationHandler to interact
* with the server so that the cookies will be placed on all requests. In Javascript within browsers,
* this is taken care of for you. Not so in the Java side.
*
* Map cookies = new HashMap();
* String url = "http://www.mycompany.com:80/json/"
*
* InvocationHandler handler = new UrlInvocationHandler(new UrlInvocationHandlerStrategyImplementation(url, ...));
* Explorer explorer = (Explorer) ProxyFactory.create(Explorer.class, handler);
*
* At this point, your Java code can do this:
*
* List files = explorer.getFiles(userId);
*
*
* @author Ken Partlow ([email protected])
* @author John DeRegnaucourt ([email protected])
*
* Copyright (c) Cedar Software LLC
*
* Licensed 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
*
* License
*
* 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.
*/
@Deprecated
public class UrlInvocationHandler implements InvocationHandler
{
public static final int SLEEP_TIME = 5000;
private final UrlInvocationHandlerStrategy _strategy;
public UrlInvocationHandler(UrlInvocationHandlerStrategy strategy)
{
_strategy = strategy;
}
public Object invoke(Object proxy, Method m, Object[] args) throws Throwable
{
int retry = _strategy.getRetryAttempts();
Object result = null;
do
{
HttpURLConnection c = null;
try
{
c = (HttpURLConnection) UrlUtilities.getConnection(_strategy.buildURL(proxy, m, args), true, true, false);
c.setRequestMethod("POST");
_strategy.setCookies(c);
// Formulate the POST data for the output stream.
byte[] bytes = _strategy.generatePostData(proxy, m, args);
c.setRequestProperty("Content-Length", String.valueOf(bytes.length));
_strategy.setRequestHeaders(c);
// send the post data
IOUtilities.transfer(c, bytes);
_strategy.getCookies(c);
// Get the return value of the call
result = _strategy.readResponse(c);
}
catch (Throwable e)
{
UrlUtilities.readErrorResponse(c);
if (retry-- > 0)
{
Thread.sleep(_strategy.getRetrySleepTime());
}
}
finally
{
UrlUtilities.disconnect(c);
}
} while (retry > 0);
try
{
checkForThrowable(result);
} catch (Throwable t) {
return null;
}
return result;
}
protected static void checkForThrowable(Object object) throws Throwable
{
if (object instanceof Throwable)
{
Throwable t;
if (object instanceof InvocationTargetException)
{
InvocationTargetException i = (InvocationTargetException) object;
t = i.getTargetException();
if (t == null)
{
t = (Throwable) object;
}
}
else
{
t = (Throwable) object;
}
t.fillInStackTrace();
throw t;
}
}
}