基於c3p0的jdbc數據源工具類

package utils.db;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import play.Logger;
import play.libs.Codec;

import java.beans.PropertyVetoException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * c3p0實現的一個數據源工廠類
 */
public class DataSourceFactory {

    // 保存所有創建的DataSource，進程停止時統一銷燬
    private static final Map<String, ComboPooledDataSource> dsPool = new ConcurrentHashMap<>();

    /**
     * 創建數據源的線程保護鎖
     * 使用讀寫鎖的原因在於，創建數據源的代碼不需要線程同步，這樣可以保證makeDataSource的效率
     * dsPool的線程安全交給ConcurrentHashMap處理
     */
    private static final ReadWriteLock rwLock = new ReentrantReadWriteLock();

    static ComboPooledDataSource getDataSource(String driver, String url, String user, String pass) {
        String dataSourceKey = Codec.hexMD5(driver + url + user);
        ComboPooledDataSource dataSource = dsPool.get(dataSourceKey);
        if (dataSource == null) {
            rwLock.readLock().lock();
            try {
                dataSource = makeDataSource(driver, url, user, pass);
                dsPool.put(dataSourceKey, dataSource);
            } finally {
                rwLock.readLock().unlock();
            }
        }
        return dataSource;
    }

    private static ComboPooledDataSource makeDataSource(String driver, String url, String user, String pass) {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();

        try {
            dataSource.setDriverClass(driver);
            System.out.println("JDBC Driver Class load completion:" + driver);
        } catch (PropertyVetoException e) {
        	System.out.println("JDBC Driver Class ["+driver+"] is not Found!");
            throw new RuntimeException("Please check your application.conf!", e);
        }
        dataSource.setJdbcUrl(url);
        dataSource.setUser(user);
        dataSource.setPassword(pass);

        // 連接池中最小連接數
        dataSource.setMinPoolSize(1);
        // 連接池中最大連接數
        dataSource.setMaxPoolSize(20);
        // 檢查連接池空閒連接的時間間隔，單位：秒
        dataSource.setIdleConnectionTestPeriod(60);
        // 最大空閒時間，指定時間中連接未被使用則會被丟棄，單位：秒
        dataSource.setMaxIdleTime(3600);
        return dataSource;
    }

    /**
     * 關閉所有數據源並清空緩存
     * 如果正在創建DataSource，closeAll將等待創建完成後執行
     */
    public static void closeAll() {
        rwLock.writeLock().lock();
        try {
            for (ComboPooledDataSource dataSource : dsPool.values()) {
                dataSource.close();
            }
            dsPool.clear();
        } finally {
            rwLock.writeLock().unlock();
        }
    }

}