1.SqlConnectImpl 数据库的连接
public class SqlConnectImplimplements Connection {
/*拿一个数据库连接*/
public static final Connection fetchConnection() {
return new SqlConnectImpl();
}
}
2.DBPool 连接池的实现
/**
* 类说明：连接池的实现
*/
public class DBPool {
private static LinkedListpool =new LinkedList();
public DBPool(int initialSize) {
if (initialSize >0) {
for (int i =0; i < initialSize; i++) {
pool.addLast(SqlConnectImpl.fetchConnection());
}
}
}
// 释放连接
public void releaseConnection(Connection connection) {
if (connection !=null) {
synchronized (pool) {
pool.addLast(connection);
pool.notifyAll();
}
}
}
// 在mills内无法获取到连接，将会返回null
public Connection fetchConnection(long mills)throws InterruptedException {
//TODO
synchronized (pool) {
if (mills <0) {
while (pool.isEmpty()) {
pool.wait();
}
return pool.removeFirst();
}else {
//超时时刻
long future = System.currentTimeMillis() + mills;
//超时时长
long remaining = mills;
while (pool.isEmpty() && remaining >0) {
pool.wait(remaining);
//重新计算等待时长
remaining = future - System.currentTimeMillis();
}
Connection connection =null;
if (!pool.isEmpty()) {
connection =pool.removeFirst();
}
return connection;
}
}
}
}
3.DBPoolTest 最后测试运行
public class DBPoolTest {
static DBPoolpool =new DBPool(10);
// 控制器:控制main线程将会等待所有Woker结束后才能继续执行
static CountDownLatchend;
public static void main(String[] args)throws Exception {
// 线程数量
int threadCount =50;
end =new CountDownLatch(threadCount);
int count =20;//每个线程的操作次数
AtomicInteger got =new AtomicInteger();//计数器：统计可以拿到连接的线程
AtomicInteger notGot =new AtomicInteger();//计数器：统计没有拿到连接的线程
for (int i =0; i < threadCount; i++) {
Thread thread =new Thread(new Worker(count, got, notGot), "worker_"+i);
thread.start();
}
end.await();// main线程在此处等待
System.out.println("总共尝试了: " + (threadCount * count));
System.out.println("拿到连接的次数： " + got);
System.out.println("没能连接的次数： " + notGot);
}
static class Workerimplements Runnable {
int count;
AtomicIntegergot;
AtomicIntegernotGot;
public Worker(int count, AtomicInteger got,
AtomicInteger notGot) {
this.count = count;
this.got = got;
this.notGot = notGot;
}
public void run() {
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和未获取到的数量notGot
Connection connection =pool.fetchConnection(1000);
if (connection !=null) {
try {
connection.createStatement();
connection.commit();
}finally {
pool.releaseConnection(connection);
got.incrementAndGet();
}
}else {
notGot.incrementAndGet();
System.out.println(Thread.currentThread().getName()
+"等待超时!");
}
}catch (Exception ex) {
}finally {
count--;
}
}
end.countDown();
}
}
}
以上内容仅代表个人学习的见解，希望可以为大家提供一个学习参考
