数据库链接池模型实现--多线程（非线程池）版

来源：互联网发布：大数据分析就业编辑：程序博客网时间：2024/06/05 22:48

由于没有使用线程池技术，需要频繁的创建和销毁线程，这无疑十分消耗和浪费系统的资源，线程池的实现参考下一篇，这里请关注下“超时等待模式”

//对当前对象枷锁public synchronized Object get(long mills){     long future = System.currentTimeMillis();     long remaining = mills;     //当超时大于0，并且result返回值不满足要求     while (result.isEmpty() && remaining > 0){          wait(remaining);          remaining = future - System.currentTimeMillis();     }     return result; }

链接池的实现

package chapter04.connection_pool.no_thread_pool;import java.sql.Connection;import java.util.LinkedList;/** * Created by tianjun on 2017/11/4. */public class ConnectionPool {    private LinkedList<Connection> pool = new LinkedList<>();    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){                //链接释放后需要进行通知，这样其他消费者能够感知到连接池中已经归还了一个连接                pool.addLast(connection);                pool.notifyAll();            }        }    }    //在mills时间内无法获取链接，就会返回null    public Connection fetchConnection(long mills) throws InterruptedException {        synchronized (pool){            if(mills<=0){                while(pool.isEmpty()){                    pool.wait();                }                return pool.removeFirst();            }else {                long future = System.currentTimeMillis();                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;            }        }    }}

链接的实现

package chapter04.connection_pool.no_thread_pool;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.sql.Connection;import java.util.concurrent.TimeUnit;/** * Created by tianjun on 2017/11/4. */public class ConnectionDriver {    static class ConnectionHandler implements InvocationHandler{        @Override        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {            if(method.getName().equals("commit")){                TimeUnit.MILLISECONDS.sleep(100);            }            return null;        }    }    //创建一个Connection的代理，在Commit时休眠100毫秒    public static final Connection createConnection(){        return (Connection) Proxy.newProxyInstance(ConnectionDriver.class.getClassLoader(),                new Class<?>[]{Connection.class},new ConnectionHandler());    }}

连接池测试

package chapter04.connection_pool.no_thread_pool;import java.sql.Connection;import java.sql.SQLException;import java.util.concurrent.CountDownLatch;import java.util.concurrent.atomic.AtomicInteger;/** * Created by tianjun on 2017/11/4. */public class ConnectionPoolTest {    static ConnectionPool pool = new ConnectionPool(10);    //保证所有的ConnectionRunner能同时开始    static CountDownLatch  start = new CountDownLatch(1);    //main线程会等待所有connectionRunner结束后才能继续执行    static CountDownLatch end;    public static void main(String[] args) throws InterruptedException {        int threadCount = 10;//线程数        end = new CountDownLatch(threadCount);        int count = 20;//每个线程获取数据库连接池的次数        AtomicInteger got = new AtomicInteger();        AtomicInteger nogot = new AtomicInteger();        for(int i=0;i<threadCount;i++){            Thread thread = new Thread(new ConnectionRunner(count ,got,nogot),"ConnectionRunnerThread");            thread.start();        }        start.countDown();        end.await();//main线程等待，直到end降为0.        System.out.println("total invoke: "+(threadCount*count));        System.out.println("got connection: "+got);        System.out.println("not got connection:"+nogot);    }    static class ConnectionRunner implements Runnable{        int count;        AtomicInteger got;        AtomicInteger nogot;        public ConnectionRunner(int count, AtomicInteger got, AtomicInteger nogot) {            this.count = count;            this.got = got;            this.nogot = nogot;        }        @Override        public void run() {            try {                start.await();            }catch (InterruptedException e) {            }            while (count > 0){                try {                    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{                        nogot.incrementAndGet();                    }                } catch (InterruptedException e) {                    e.printStackTrace();                }finally {                    count--;                }            }            end.countDown();        }    }}

阅读全文

0 0