When to use @Singleton in a Jersey resource

Question

I have a Jersey resource that access the database. Basically it opens a database connection in the initialization of the resource. Performs queries on the resource\'s methods.

Answer 1

You best option is to use a framework like Spring with Jersey which I outlined in a similar post. The only difference is that instead of injecting a service bean you would inject a pooled DataSource and this can easily be configured using c3p0.

Example applicationContext.xml, notice the "scope" is set to prototype which is equivalent to a singleton in Spring parlance.

In your MyResource.java you would simply add the following and Spring would inject it appropriately.

private DataSource pooledDataSource;
public void setPooledDataSource(DataSource pooledDataSource) {
    this.pooledDataSource = pooledDataSource;
}

Then you could change your ResponseGenerator to accept the DataSource and use this to query the database.