CopyOnWriteArrayList再续

相关文章
http://wangxinchun.iteye.com/blog/1872212
CopyOnWriteArrayList 适合读频繁，写不频繁的情况，最重要的是如果list中的数据量非常大，请不要使用这个，那在写的时候复制到代价将会非常大。

这时可以考虑使用Vector 或者collections.synchronizedlist 。

但是这样读和读之间依然是互斥的，性能肯定差。
下面这个实现通过读写锁分离的思想，很简单的可以实现读和读是并行的，读和写是互斥的，写和写是互斥的。

如果有问题，请指正～

源码如下：

package cn.javaframe.validator;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * @author xinchun.wang
 */
public class ReadWriteLockArrayList<T> {
	private List<T> list = new ArrayList<T>();
	private ReadWriteLock lock = new ReentrantReadWriteLock();
	private Lock writeLock = lock.writeLock();
	private Lock readLock = lock.readLock();

	public int size() {
		readLock.lock();
		try {
			return list.size();
		} finally {
			readLock.unlock();
		}
	}

	public boolean isEmpty() {
		readLock.lock();
		try {
			return list.isEmpty();
		} finally {
			readLock.unlock();
		}
	}

	public boolean contains(Object o) {
		readLock.lock();
		try {
			return list.contains(o);
		} finally {
			readLock.unlock();
		}
	}

	public Iterator<T> iterator() {
		throw new UnsupportedOperationException();
	}

	public Object[] toArray() {
		readLock.lock();
		try {
			return list.toArray();
		} finally {
			readLock.unlock();
		}
	}

	public boolean add(T e) {
		writeLock.lock();
		try {
			return list.add(e);
		} finally {
			writeLock.unlock();
		}
	}

	public boolean remove(T o) {
		writeLock.lock();
		try {
			return list.remove(o);
		} finally {
			writeLock.unlock();
		}
	}

	public void clear() {
		writeLock.lock();
		try {
			list.clear();
		} finally {
			writeLock.unlock();
		}
	}

	public T get(int index) {
		readLock.lock();
		try {
			return list.get(index);
		} finally {
			readLock.unlock();
		}

	}

	public T remove(int index) {
		writeLock.lock();
		try {
			return list.remove(index);
		} finally {
			writeLock.unlock();
		}
	}

	public int indexOf(Object o) {
		readLock.lock();
		try {
			return list.indexOf(o);
		} finally {
			readLock.unlock();
		}

	}

	public int lastIndexOf(Object o) {
		readLock.lock();
		try {
			return list.lastIndexOf(o);
		} finally {
			readLock.unlock();
		}
	}

	public boolean addAll(Collection<? extends T> c) {
		writeLock.lock();
		try {
			return list.addAll(c);
		} finally {
			writeLock.unlock();
		}
	}

	public boolean addAll(int index, Collection<? extends T> c) {
		writeLock.lock();
		try {
			return list.addAll(index, c);
		} finally {
			writeLock.unlock();
		}
	}

	public boolean removeAll(Collection<?> c) {
		writeLock.lock();
		try {
			return list.removeAll(c);
		} finally {
			writeLock.unlock();
		}
	}

	public T set(int index, T element) {
		writeLock.lock();
		try {
			return list.set(index, element);
		} finally {
			writeLock.unlock();
		}
	}

	public void add(int index, T element) {
		writeLock.lock();
		try {
			list.add(index, element);
		} finally {
			writeLock.unlock();
		}
	}

}