JAVA数据库连接池实现

连接池的管理用了了享元模式，这里对连接池进行简单设计。

一、设计思路

     1.连接池配置属性DBbean：里面存放可以配置的一些属性

     2.连接池接口IConnectionPool：里面定义一些基本的获取连接的一些方法

     3.接口实现ConnectionPool：对上面操作进行实现，并加入一些其他方法

     4.连接池管理ConnectionPoolManager：管理所有的不同的连接池，所有的连接都能通过这里进行获得连接

     5.另外还有几个测试类，和连接信息模拟的类，这里就不进行xml 和配置文件信息的读取了

package pool;
/**
 * 这是外部可以配置的连接池属性
 * 可以允许外部配置，拥有默认值
 * @author Ran
 *
 */
public class DBbean {
	// 连接池属性
	private String driverName;
	private String url;
	private String userName;
	private String password;
	// 连接池名字
	private String poolName;
	private int minConnections = 1; // 空闲池，最小连接数
	private int maxConnections = 10; // 空闲池，最大连接数
	
	private int initConnections = 5;// 初始化连接数
	
	private long connTimeOut = 1000;// 重复获得连接的频率
	
	private int maxActiveConnections = 100;// 最大允许的连接数，和数据库对应
	
	private long connectionTimeOut = 1000*60*20;// 连接超时时间，默认20分钟
	
	private boolean isCurrentConnection = true; // 是否获得当前连接，默认true
	
	private boolean isCheakPool = true; // 是否定时检查连接池
	private long lazyCheck = 1000*60*60;// 延迟多少时间后开始 检查
	private long periodCheck = 1000*60*60;// 检查频率
	
	
	
	public DBbean(String driverName, String url, String userName,
			String password, String poolName) {
		super();
		this.driverName = driverName;
		this.url = url;
		this.userName = userName;
		this.password = password;
		this.poolName = poolName;
	}
	public DBbean() {
	}
	public String getDriverName() {
		if(driverName == null){
			driverName = this.getDriverName()+"_"+this.getUrl();
		}
		return driverName;
	}
	public void setDriverName(String driverName) {
		this.driverName = driverName;
	}
	public String getUrl() {
		return url;
	}
	public void setUrl(String url) {
		this.url = url;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getPoolName() {
		return poolName;
	}
	public void setPoolName(String poolName) {
		this.poolName = poolName;
	}
	public int getMinConnections() {
		return minConnections;
	}
	public void setMinConnections(int minConnections) {
		this.minConnections = minConnections;
	}
	public int getMaxConnections() {
		return maxConnections;
	}
	public void setMaxConnections(int maxConnections) {
		this.maxConnections = maxConnections;
	}
	public int getInitConnections() {
		return initConnections;
	}
	public void setInitConnections(int initConnections) {
		this.initConnections = initConnections;
	}

	public int getMaxActiveConnections() {
		return maxActiveConnections;
	}
	public void setMaxActiveConnections(int maxActiveConnections) {
		this.maxActiveConnections = maxActiveConnections;
	}
	public long getConnTimeOut() {
		return connTimeOut;
	}
	public void setConnTimeOut(long connTimeOut) {
		this.connTimeOut = connTimeOut;
	}
	public long getConnectionTimeOut() {
		return connectionTimeOut;
	}
	public void setConnectionTimeOut(long connectionTimeOut) {
		this.connectionTimeOut = connectionTimeOut;
	}
	public boolean isCurrentConnection() {
		return isCurrentConnection;
	}
	public void setCurrentConnection(boolean isCurrentConnection) {
		this.isCurrentConnection = isCurrentConnection;
	}
	public long getLazyCheck() {
		return lazyCheck;
	}
	public void setLazyCheck(long lazyCheck) {
		this.lazyCheck = lazyCheck;
	}
	public long getPeriodCheck() {
		return periodCheck;
	}
	public void setPeriodCheck(long periodCheck) {
		this.periodCheck = periodCheck;
	}
	public boolean isCheakPool() {
		return isCheakPool;
	}
	public void setCheakPool(boolean isCheakPool) {
		this.isCheakPool = isCheakPool;
	}
	
	
	
}

 

package pool;

import java.sql.Connection;
import java.sql.SQLException;

public interface IConnectionPool {
	// 获得连接
	public Connection  getConnection();
	// 获得当前连接
	public Connection getCurrentConnecton();
	// 回收连接
	public void releaseConn(Connection conn) throws SQLException;
	// 销毁清空
	public void destroy();
	// 连接池是活动状态
	public boolean isActive();
	// 定时器，检查连接池
	public void cheackPool();
}

 

package pool;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.Vector;

public class ConnectionPool implements IConnectionPool {
	// 连接池配置属性
	private DBbean dbBean;
	private boolean isActive = false; // 连接池活动状态
	private int contActive = 0;// 记录创建的总的连接数
	
	// 空闲连接
	private List<Connection> freeConnection = new Vector<Connection>();
	// 活动连接
	private List<Connection> activeConnection = new Vector<Connection>();
	// 将线程和连接绑定，保证事务能统一执行
	private static ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>();
	
	public ConnectionPool(DBbean dbBean) {
		super();
		this.dbBean = dbBean;
		init();
		cheackPool();
	}

	// 初始化
	public void init() {
		try {
			Class.forName(dbBean.getDriverName());
			for (int i = 0; i < dbBean.getInitConnections(); i++) {
				Connection conn;
				conn = newConnection();
				// 初始化最小连接数
				if (conn != null) {
					freeConnection.add(conn);
					contActive++;
				}
			}
			isActive = true;
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	
	// 获得当前连接
	public Connection getCurrentConnecton(){
		// 默认线程里面取
		Connection conn = threadLocal.get();
		if(!isValid(conn)){
			conn = getConnection();
		}
		return conn;
	}

	// 获得连接
	public synchronized Connection getConnection() {
		Connection conn = null;
		try {
			// 判断是否超过最大连接数限制
			if(contActive < this.dbBean.getMaxActiveConnections()){
				if (freeConnection.size() > 0) {
					conn = freeConnection.get(0);
					if (conn != null) {
						threadLocal.set(conn);
					}
					freeConnection.remove(0);
				} else {
					conn = newConnection();
				}
				
			}else{
				// 继续获得连接,直到从新获得连接
				wait(this.dbBean.getConnTimeOut());
				conn = getConnection();
			}
			if (isValid(conn)) {
				activeConnection.add(conn);
				contActive ++;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return conn;
	}

	// 获得新连接
	private synchronized Connection newConnection()
			throws ClassNotFoundException, SQLException {
		Connection conn = null;
		if (dbBean != null) {
			Class.forName(dbBean.getDriverName());
			conn = DriverManager.getConnection(dbBean.getUrl(),
					dbBean.getUserName(), dbBean.getPassword());
		}
		return conn;
	}

	// 释放连接
	public synchronized void releaseConn(Connection conn) throws SQLException {
		if (isValid(conn)&& !(freeConnection.size() > dbBean.getMaxConnections())) {
			freeConnection.add(conn);
			activeConnection.remove(conn);
			contActive --;
			threadLocal.remove();
			// 唤醒所有正待等待的线程，去抢连接
			notifyAll();
		}
	}

	// 判断连接是否可用
	private boolean isValid(Connection conn) {
		try {
			if (conn == null || conn.isClosed()) {
				return false;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return true;
	}

	// 销毁连接池
	public synchronized void destroy() {
		for (Connection conn : freeConnection) {
			try {
				if (isValid(conn)) {
					conn.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		for (Connection conn : activeConnection) {
			try {
				if (isValid(conn)) {
					conn.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		isActive = false;
		contActive = 0;
	}

	// 连接池状态
	@Override
	public boolean isActive() {
		return isActive;
	}
	
	// 定时检查连接池情况
	@Override
	public void cheackPool() {
		if(dbBean.isCheakPool()){
			new Timer().schedule(new TimerTask() {
			@Override
			public void run() {
			// 1.对线程里面的连接状态
			// 2.连接池最小 最大连接数
			// 3.其他状态进行检查，因为这里还需要写几个线程管理的类，暂时就不添加了
			System.out.println("空线池连接数："+freeConnection.size());
			System.out.println("活动连接数：："+activeConnection.size());
			System.out.println("总的连接数："+contActive);
				}
			},dbBean.getLazyCheck(),dbBean.getPeriodCheck());
		}
	}
}

 

package pool;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Hashtable;
/**
 * 连接管理类
 * @author Ran
 *
 */
public class ConnectionPoolManager {
	
	
	// 连接池存放
	public Hashtable<String,IConnectionPool> pools = new Hashtable<String, IConnectionPool>();
	
	// 初始化
	private ConnectionPoolManager(){
		init();
	}
	// 单例实现
	public static ConnectionPoolManager getInstance(){
		return Singtonle.instance;
	}
	private static class Singtonle {
		private static ConnectionPoolManager instance =  new ConnectionPoolManager();
	}
	
	
	// 初始化所有的连接池
	public void init(){
		for(int i =0;i<DBInitInfo.beans.size();i++){
			DBbean bean = DBInitInfo.beans.get(i);
			ConnectionPool pool = new ConnectionPool(bean);
			if(pool != null){
				pools.put(bean.getPoolName(), pool);
				System.out.println("Info:Init connection successed ->" +bean.getPoolName());
			}
		}
	}
	
	// 获得连接,根据连接池名字 获得连接
	public Connection  getConnection(String poolName){
		Connection conn = null;
		if(pools.size()>0 && pools.containsKey(poolName)){
			conn = getPool(poolName).getConnection();
		}else{
			System.out.println("Error:Can't find this connecion pool ->"+poolName);
		}
		return conn;
	}
	
	// 关闭，回收连接
	public void close(String poolName,Connection conn){
			IConnectionPool pool = getPool(poolName);
			try {
				if(pool != null){
					pool.releaseConn(conn);
				}
			} catch (SQLException e) {
				System.out.println("连接池已经销毁");
				e.printStackTrace();
			}
	}
	
	// 清空连接池
	public void destroy(String poolName){
		IConnectionPool pool = getPool(poolName);
		if(pool != null){
			pool.destroy();
		}
	}
	
	// 获得连接池
	public IConnectionPool getPool(String poolName){
		IConnectionPool pool = null;
		if(pools.size() > 0){
			 pool = pools.get(poolName);
		}
		return pool;
	}
}

 

package pool;

import java.util.ArrayList;
import java.util.List;
/**
 * 初始化，模拟加载所有的配置文件
 * @author Ran
 *
 */
public class DBInitInfo {
	public  static List<DBbean>  beans = null;
	static{
		beans = new ArrayList<DBbean>();
		// 这里数据 可以从xml 等配置文件进行获取
		// 为了测试，这里我直接写死
		DBbean beanOracle = new DBbean();
		beanOracle.setDriverName("oracle.jdbc.driver.OracleDriver");
		beanOracle.setUrl("jdbc:oracle:thin:@7MEXGLUY95W1Y56:1521:orcl");
		beanOracle.setUserName("mmsoa");
		beanOracle.setPassword("password1234");
		
		beanOracle.setMinConnections(5);
		beanOracle.setMaxConnections(100);
		
		beanOracle.setPoolName("testPool");
		beans.add(beanOracle);
	}
}

 

    测试：

   

package pool;

import java.sql.Connection;
/**
 * 模拟线程启动，去获得连接
 * @author Ran
 *
 */
public class ThreadConnection implements Runnable{
	private IConnectionPool pool;
	@Override
	public void run() {
		pool = ConnectionPoolManager.getInstance().getPool("testPool");
	}
	
	public Connection getConnection(){
		Connection conn = null;
		if(pool != null && pool.isActive()){
			conn = pool.getConnection();
		}
		return conn;
	}
	
	public Connection getCurrentConnection(){
		Connection conn = null;
		if(pool != null && pool.isActive()){
			conn = pool.getCurrentConnecton();
		}
		return conn;
	}
}

 

package pool;



public class Client {
	public static void main(String[] args) throws InterruptedException {
		// 初始化连接池
		Thread t = init();
		t.start();
		t.join();
		
		ThreadConnection a = new ThreadConnection();
		ThreadConnection b = new ThreadConnection();
		ThreadConnection c = new ThreadConnection();
		Thread t1 = new Thread(a);
		Thread t2 = new Thread(b);
		Thread t3 = new Thread(c);
		
		
		// 设置优先级，先让初始化执行，模拟 线程池 先启动
		// 这里仅仅表面控制了，因为即使t 线程先启动，也不能保证pool 初始化完成，为了简单模拟，这里先这样写了
		t1.setPriority(10);
		t2.setPriority(10);
		t3.setPriority(10);
		t1.start();
		t2.start();
		t3.start();
		
		System.out.println("线程A-> "+a.getConnection());
		System.out.println("线程B-> "+b.getConnection());
		System.out.println("线程C-> "+c.getConnection());
	}

	// 初始化
	public static Thread init() {
		Thread t = new Thread(new Runnable() {
			@Override
			public void run() {
				IConnectionPool  pool = initPool();
				while(pool == null || !pool.isActive()){
					pool = initPool();
				}
			}
		});
		return t;
	}
	
	public static IConnectionPool initPool(){
		return ConnectionPoolManager.getInstance().getPool("testPool");
	}

}

 

小结 ：

          1.连接池诞生原因是，如果每次都从数据库获得连接，时间比较长，因此我们提前做建立一些连接，放在连接池里面，每次都从里面取

          2.上面仅仅写了连接池基本原理，关于多线程下连接池的管理没写，后面对多线程操作熟练了添加吧