ConnectionDriver 获取驱动
public class ConnectionDriver {
static class ConnectionHandler implements InvocationHandler {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String commit = "commit";
if (commit.equals(method.getName())) {
TimeUnit.MILLISECONDS.sleep(100);
}
return null;
}
}
/**
* 通过动态代理来获取一个Connection实例,在commit时休眠10秒
*
* @return
*/
public static final Connection createConnection() {
return (Connection) Proxy.newProxyInstance(ConnectionDriver.class.getClassLoader(), new Class<?>[]{Connection.class}, new ConnectionHandler());
}
}
简单连接池
public class ConnectionPool {
private LinkedList<Connection> pool = new LinkedList<Connection>();
public ConnectionPool(int initialSize) {
if (initialSize > 0) {
for (int i = 0; i < initialSize; i++) {
pool.addLast(ConnectionDriver.createConnection());
}
}
}
public void releaseConnection(Connection connection) {
if (connection != null) {
synchronized (pool) {
//连接释放后需要进行通知，这样其他消费者能感知到连接池中已经归还了一个连接
pool.addLast(connection);
pool.notifyAll();
}
}
}
public Connection fetchConnection(long mills) throws InterruptedException {
synchronized (pool) {
//完全超时
if (mills <= 0) {
while (pool.isEmpty()) {
pool.wait();
}
return pool.removeFirst();
} else {
long future = System.currentTimeMillis() + mills;
long remaining = mills;
while (pool.isEmpty() && remaining > 0) {
pool.wait(remaining);
remaining = future - System.currentTimeMillis();
}
Connection result = null;
if (pool.isEmpty()) {
result = pool.removeFirst();
}
return result;
}
}
}
}
测试
public class ConnectionPoolTest {
private static ConnectionPool pool = new ConnectionPool(10);
//保证所有ConnectionRunner能同时开始
private static CountDownLatch start = new CountDownLatch(1);
//main线程将会等待所有ConnectionRunner结束后才能继续执行
private static CountDownLatch end;
public static void main(String[] args) {
//线程数量，可以修改线程数量进行观察
int threadCount = 10;
end = new CountDownLatch(threadCount);
int count = 20;
AtomicInteger got = new AtomicInteger();
AtomicInteger notGot = new AtomicInteger();
for (int i = 0; i < threadCount; i++) {
final Thread thread = new Thread(new ConnctionRunner(count, got, notGot), "ConnctionRunnerThread");
}
}
static class ConnctionRunner implements Runnable {
int count;
AtomicInteger got;
AtomicInteger notGot;
public ConnctionRunner(int count, AtomicInteger got, AtomicInteger notGot) {
this.count = count;
this.got = got;
this.notGot = notGot;
}
@Override
public void run() {
try {
start.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
while (count > 0) {
try {
//从线程池中获取连接，如果1000ms内无法获取到，将会返回null
//分别统计连接获取的数量got和为获取的数量notGot
final Connection connection = pool.fetchConnection(1000);
if (connection != null) {
try {
connection.createStatement();
connection.commit();
} catch (SQLException e) {
e.printStackTrace();
} finally {
pool.releaseConnection(connection);
got.incrementAndGet();
}
} else {
notGot.incrementAndGet();
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
count--;
}
}
end.countDown();
}
}
}
public class Test2 {
public static void main(String[] args) {
AtomicReferenceArray<String> referenceArray = new AtomicReferenceArray<String>(3);
final String s1 = referenceArray.getAndSet(0, "xiaofei");
System.out.println(s1);
referenceArray.set(1, "jiandong");
final String s2 = referenceArray.get(0);
System.out.println(s2);
final AtomicInteger atomicInteger = new AtomicInteger();
final int i1 = atomicInteger.incrementAndGet();
System.out.println(i1);
final int i2 = atomicInteger.getAndIncrement();
System.out.println(i2);
final int i3 = atomicInteger.intValue();
System.out.println(i3);
}
}
