数据库连接池

public class MyPool {
    private int init_count = 3;
    private int max_count = 6;
    private int curr_count = 0;
    private LinkedList<Connection> pool = new LinkedList<Connection>();

    public MyPool(){
        for(int i = 0 ;i < init_count ;i++)
        {
            curr_count++;
            pool.addLast(createConnection());
        }
    }

    /**
     * 使用代理类，每次调用connection的close方法，都把连接放入连接池中
     */
    private Connection createConnection(){
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection connection = DriverManager.getConnection("jdbc:mysql:///test", "root", "juaner767");
            Connection proxy = (Connection)Proxy.newProxyInstance(
                    connection.getClass().getClassLoader(),//类加载器
//                    connection.getClass().getInterfaces() 实现的接口，对象是一个具体的类时这样使用
                    new Class[]{Connection.class}, //connection是接口，所以要这样使用
                    new InvocationHandler() {
                        //当调用connection对象方法的时候，会自动触发事务处理器
                        @Override
                        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                            String name = method.getName();
                            Object result= null;
                            //当执行close方法时，把连接放入连接池
                            if("close".equals(name))
                            {
                                System.out.println("调用对象被监测的接口");
                                releaseConnection(connection);
                            }else{
                                result = method.invoke(connection, args);
                            }
                            return result;
                        }
                    }
            );
            return proxy;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
    public Connection getConnection(){
        Connection connection = null;
        if(pool.size() > 0){
            connection = pool.removeFirst();
        }else{
            if(curr_count < max_count){
                curr_count++;
                connection = createConnection();
            }else {
                throw new RuntimeException("当前已经达到最大连接数，无法获取连接!");
            }
        }
        return connection;
    }

    public void releaseConnection(Connection connection){
        if(connection == null)
            return;
        if(pool.size() < init_count)
            pool.addLast(connection);
        else{
            try {
                connection.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
            curr_count--;
        }
    }
}

url=jdbc:mysql:///student
driverClassName=com.mysql.jdbc.Driver
username=root
password=juaner767
initialSize=3
maxActive=6
maxIdle=3000

   @Test
    public void test2() throws Exception {
        //加载配置文件
        Properties prop = new Properties();
        InputStream in = Demo1.class.getResourceAsStream("db.properties");
        prop.load(in);

        DataSource dataSource = BasicDataSourceFactory.createDataSource(prop);
        Connection connection = dataSource.getConnection();
        connection.prepareStatement("DELETE from student_info WHERE stuId = 2008006").executeUpdate();
        connection.close();
    }

<c3p0-config>
  <default-config>
     <property name="jdbcUrl">jdbc:mysql://localhost:3306/student</property>
     <property name="driverClass">com.mysql.jdbc.Driver</property>
     <property name="user">root</property>
     <property name="password">juaner767</property>
     <property name="initialPoolSize">3</property>
     <property name="maxPoolSize">6</property>
     <property name="maxIdleTime">1000</property>
  </default-config>
</c3p0-config>

    @Test
    public void test2()throws Exception{
        //自动加载src下的c3p0的配置文件c3p0-config.xml
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        Connection connection = dataSource.getConnection();
        PreparedStatement preparedStatement  = null;
        String sql ="INSERT INTO student_info (stuName,telephone) VALUES(?,?) ";
        preparedStatement = connection.prepareStatement(sql);
        for(int i = 0;i<10;i++) {
            preparedStatement.setString(1,"测试"+i);
            preparedStatement.setInt(2,1353356234);
            preparedStatement.executeUpdate();
        }
        connection.close();
    }

        <!--连接池配置-->
        <!--连接池管理类、驱动管理类-->
        <property name="hibernate.connection.provider_class">
            org.hibernate.connection.C3P0ConnectionProvider
        </property>
        <!--配置连接池参数信息-->
        <property name="hibernate.c3p0.min_size">2</property>
        <property name="hibernate.c3p0.max_size">4</property>
        <property name="hibernate.c3p0.timeout">5000</property>
        <property name="hibernate.c3p0.max_statements">10</property>
        <property name="hibernate.c3p0.idle_test_period">30000</property>
        <property name="hibernate.c3p0.acquire_increment">2</property>