如何使Jersey Rest POST请求同步

Question

How can i make Jersey REST POST request Synchronized so that if one request is in process no other request can be made.

i tried making method synchronized but it didn't work.

Answer 1

Instead of trying to synchronize your service methods and start / stop your GraphDatabaseService per request it might be interesting to start your GraphDatabaseService in a ServletContextListener and then access it through the web application's context. This takes advantage of the fact that GraphDatabaseService is thread safe.

Perhaps a listener like this:

public class ExampleListener implements ServletContextListener {

  public void contextInitialized(ServletContextEvent sce) {
    sce.getServletContext().setAttribute("graphDb", new GraphDatabaseFactory().newEmbeddedDatabase("/tmp/GraphDB"));
  }

  public void contextDestroyed(ServletContextEvent sce) {
    ((GraphDatabaseService)sce.getServletContext().getAttribute("graphDb")).shutdown();
  }

}

which you can initialize in your web.xml like this:

<listener>
  <listener-class>org.example.ExampleListener</listener-class>
</listener>

and then utilize in a REST method like this:

@POST
public void graphOperation(@Context ServletContext context) {
  GraphDatabaseService graphDb = (GraphDatabaseService)context.getAttribute("graphDb");
  // Graph operations here...
}

You could even add your ServletContext to your service class constructor and get the attributes you need as member fields of your service class to make it more convenient.