JAVA数据库连接池实现（转）

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

本文转自http://greemranqq.iteye.com/blog/1969273 感谢作者