public class DBCPUtils {
//1.定义常量 保存数据库连接的相关信息
public static final String DRIVERNAME = "com.mysql.jdbc.Driver";
public static final String URL = "jdbc:mysql://localhost:3306/db5?characterEncoding=UTF-8";
public static final String USERNAME = "root";
public static final String PASSWORD = "123456";
//2.创建连接池对象 (有DBCP提供的实现类)
public static BasicDataSource dataSource = new BasicDataSource();
//3.使用静态代码块进行配置
static{
dataSource.setDriverClassName(DRIVERNAME);
dataSource.setUrl(URL);
dataSource.setUsername(USERNAME);
dataSource.setPassword(PASSWORD);
}

//4.获取连接的方法
public static Connection getConnection() throws SQLException {
//从连接池中获取连接
Connection connection = dataSource.getConnection();
return connection;
}
//5.释放资源方法
public static void close(Connection con, Statement statement){
if(con != null && statement != null){
try {
statement.close();
//归还连接
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static void close(Connection con, Statement statement, ResultSet resultSet){
if(con != null && statement != null && resultSet != null){
try {
resultSet.close();
statement.close();
//归还连接
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}

public class TestDBCP {
/*
* 测试DBCP连接池
* */
public static void main(String[] args) throws SQLException {
//1.从DBCP连接池中拿到连接
Connection con = DBCPUtils.getConnection();
//2.获取Statement对象
Statement statement = con.createStatement();
//3.查询所有员工的姓名
String sql = "select ename from employee";
ResultSet resultSet = statement.executeQuery(sql);
//4.处理结果集
while(resultSet.next()){
String ename = resultSet.getString("ename");
System.out.println("员工姓名: " + ename);
}
//5.释放资源
DBCPUtils.close(con,statement,resultSet);
}
}