Jdbc core code 使用手册

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import com.alibaba.druid.pool.DruidPooledConnection;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

/**
 * jdbc core api
 *
 * @author ysj 2019-10-18
 */
public class JdbcUtils {
    private static final Logger log = LoggerFactory.getLogger(JdbcUtils.class);

    private static DruidDataSource dataSource;

    static {
        Properties dbProp = loadProperties("db.properties");
        try {
            dataSource = (DruidDataSource) DruidDataSourceFactory.createDataSource(dbProp);
        } catch (Exception e) {
            log.error("数据库连接池创建失败");
            e.printStackTrace();
        }
    }

    /** 常用函数 */
    public void local() {
        try {
            DruidPooledConnection connection = dataSource.getConnection();
            connection.setAutoCommit(false);
            PreparedStatement statement = connection.prepareStatement("select ...");
            // sql中占位符？设置第一个参数值，index start with 1
            statement.setString(1,"param1");

            ResultSet resultSet = statement.executeQuery();
            resultSet.next();
            // get 结果集中对应列的值
            resultSet.getString("field");
            
            connection.commit();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /** 加载数据库配置  这里通过文件流加载数据库连接相关属性，可以有多种方式 */
    private static Properties loadProperties(String path) {
        return null; // 此处省略
    }

    /** 单例 */
    public static synchronized JdbcUtils getInstance() {
        return new JdbcUtils();
    }
}