工具类4

package cn.itcast.jdbc;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

public final class JdbcUtils {

    private static DataSource myDataSource = null;

    private JdbcUtils() {
    }

    static {
        try {
            Properties prop = new Properties();
            InputStream is = JdbcUtils.class.getClassLoader()
                    .getResourceAsStream("dbcpconfig.properties");
            prop.load(is);
            myDataSource = BasicDataSourceFactory.createDataSource(prop); // 屏蔽了创建数据源的过程
        } catch (Exception e) {
            throw new ExceptionInInitializerError(e);
        }
    }

    public static Connection getConnection() throws SQLException {
        // return DriverManager.getConnection(url, user, password);
        return myDataSource.getConnection(); // 取连接
    }

    public static void free(ResultSet rs, Statement st, Connection conn) {
        try {
            if (rs != null)
                rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (st != null)
                    st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (conn != null)
                        conn.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}