Throttle HTTP request in Java Servlet

In a java servlet, how开发者_如何学编程 can I throttle http requests coming from users based on the client's IP address? I do not want to serve more than X requests per second coming from a particular source IP address where X is configurable and having practical values in [0.1; 10] range (from 1 request in 10 sec to 10 requests per sec).

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The owasp-esapi-java project, hosted at code.google.com, has an implementation of a throttle filter that you can use "as is" or use as inspiration for your own.

You can check the code at the following link:

http://code.google.com/p/owasp-esapi-java/source/browse/trunk/src/main/java/org/owasp/esapi/filters/RequestRateThrottleFilter.java

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Use a servlet filter: if you're on Jetty 7.0 or higher there is this

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I would write a Filter for that task.

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As @EJP said, using a Filter with a HashMap that stores the last access time by IP address key. 10 requests a second would translate to 100ms between calls, minimum. Sending a server busy error code back and killing the request will quickly close the resources used by the connection. There are prebuilt solutions for Apache if that's an option for you.

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Check if the container you are using provides this kind of Denial Of Service. If no, then you would have to go with a filter.

ServletRequest.getRemoteHost() gives you access to the client IP.