JDBC（powernode 文档）源代码

package com.bjpowernode.jdbc._08连接池.service.impl; import com.bjpowernode.jdbc._08连接池.domain.PoolConnection; import com.bjpowernode.jdbc._08连接池.service.IPool; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.Driver; import java.sql.DriverManager; import java.sql.SQLException; import java.util.Properties; import java.util.Vector; public class JdbcPool implements IPool { //驱动 private static String jdbcDriver; //连接地址 private static String jdbcUrl; //数据库用户名 private static String username; //数据库密码 private static String password; //初始化连接数 private static Integer initConnectCount; //最大连接数 private static Integer maxConnects; //当连接不够时自动增长的数 private static Integer incrementCount; //因为Vector是线程安全的，所有暂时选择它 private static Vector<PoolConnection> connections = new Vector<>(); /* * 通过实例初始化块来初始化 */ { //读取对应的配置文件，加载入properties中，并设置到对应的参数中 InputStream is = JdbcPool.class.getClassLoader().getResourceAsStream("jdbc.properties"); Properties properties = new Properties(); try { properties.load(is); } catch (IOException e) { e.printStackTrace(); } jdbcDriver = properties.getProperty("jdbcDriver"); jdbcUrl = properties.getProperty("jdbcUrl"); username = properties.getProperty("username"); password = properties.getProperty("password"); initConnectCount = Integer.valueOf(properties.getProperty("initConnectCount")); maxConnects = Integer.valueOf(properties.getProperty("maxConnects")); incrementCount = Integer.valueOf(properties.getProperty("incrementCount")); try { /* * 注册jdbc驱动 * */ Driver driver = (Driver) Class.forName(jdbcDriver).newInstance(); DriverManager.registerDriver(driver); /* * 根据initConnectCount来初始化连接池 * */ createConnections(initConnectCount); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } /** * 获取可用连接 */ @Override public PoolConnection getConnection() { if (connections.isEmpty()) { System.out.println("连接池中没有连接"); throw new RuntimeException("连接池中没有连接"); } return getActiveConnection(); } /** * 同步方法来获取连接池中可用连接，在多线程情况下，只有一个线程访问该方法来获取连接，防止由于多线程情况下多个线程获取同一个连接从而引起出错 */ private synchronized PoolConnection getActiveConnection() { /* * 通过循环来获取可用连接，若获取不到可用连接，则依靠无限循环来继续获取 * */ while (true) { for (PoolConnection con : connections) { if (!con.isUse()) { Connection trueConn = con.getConn(); try { //验证连接是否失效 0表示不校验超时 if (!trueConn.isValid(0)) { con.setConn(DriverManager.getConnection(jdbcUrl, username, password)); } } catch (SQLException e) { e.printStackTrace(); } con.setUse(true); return con; } } /* * 根据连接池中连接数量从而判断是否增加对应的数量的连接 * */ if (connections.size() <= maxConnects - incrementCount) { createConnections(incrementCount); } else if (connections.size() < maxConnects && connections.size() > maxConnects - incrementCount) { createConnections(maxConnects - connections.size()); } } } /* * 创建对应数量的连接并放入连接池中 * */ private void createConnections(int count) { for (int i = 0; i < count; i++) { if (maxConnects > 0 && connections.size() >= maxConnects) { System.out.println("连接池中连接数量已经达到最大值"); throw new RuntimeException("连接池中连接数量已经达到最大值"); } try { Connection connection = DriverManager.getConnection(jdbcUrl, username, password); /* * 将连接放入连接池中，并将状态设为可用 * */ connections.add(new PoolConnection(connection, false)); } catch (SQLException e) { e.printStackTrace(); } } } /* * 获取连接池中连接数量 * */ public int getSize() { return connections.size(); } @Override public Connection getConnectionNoPool() { Connection connection = null; try { connection = DriverManager.getConnection(jdbcUrl, username, password); } catch (SQLException e) { e.printStackTrace(); } return connection; } }