ThreadLocalInvoker.java

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package com.sun.jersey.server.impl;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;


/**
 * A proxy invocation handler that delegates all methods to a thread
 * local instance
 */
public class ThreadLocalInvoker<T> implements InvocationHandler {
    private ThreadLocal<T> threadLocalInstance = new ThreadLocal<T>();

    private ThreadLocal<T> immutableThreadLocalInstance;
    
    public void set(T threadLocalInstance) {
        this.threadLocalInstance.set(threadLocalInstance);
    }
    
    public T get() {
        return this.threadLocalInstance.get();
    }
    
    public ThreadLocal<T> getThreadLocal() {
        return threadLocalInstance;
    }
    
    public ThreadLocal<T> getImmutableThreadLocal() {
        if (immutableThreadLocalInstance == null) {
            immutableThreadLocalInstance = new ThreadLocal<T>() {
                @Override
                public T get() {
                    return ThreadLocalInvoker.this.get();
                }

                @Override
                public void remove() {
                    throw new IllegalStateException();
                }

                @Override
                public void set(T t) {
                    throw new IllegalStateException();
                }
            };
        }
        return immutableThreadLocalInstance;
    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if (threadLocalInstance.get() == null)
            throw new IllegalStateException("No thread local value in scope for proxy of " + proxy.getClass());
        
        try {
            return method.invoke(threadLocalInstance.get(), args);
        } catch (IllegalAccessException ex) {
            throw new IllegalStateException(ex);
        } catch (InvocationTargetException ex) {
            throw ex.getTargetException();
        }
    }
}