Java Durid进行JDBC连接详解

<!-- mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.49</version>
</dependency>
<!-- druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.27</version>
</dependency>

package cn.kgc.utils;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayHandler;
import org.apache.commons.dbutils.handlers.ArrayListHandler;
import org.apache.log4j.Logger;
import java.io.File;
import java.io.FileInputStream;
import java.io.Serializable;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
/**
 * 【JDBC】业务工具类
 */
public class JDBCReadUtils implements Serializable {
    private static Logger logger = Logger.getLogger(JDBCReadUtils.class);
    /**
     * 实现JDBCHelper的单例化
     */
    private static JDBCReadUtils instance = null;
    private QueryRunner runner = null;
    /**
     * 实现单例的过程中，创建唯一的数据库连接池
     */
    private JDBCReadUtils(String url) {
        Properties properties = new Properties();
        try {
            properties.load(new FileInputStream(new File(url)));
            runner = new QueryRunner(DruidDataSourceFactory.createDataSource(properties));
        } catch (Exception e) {
            logger.error(e.getMessage(), e);
        }
    }
    public JDBCReadUtils() {
    }
    /**
     * 获取单例
     *
     * @return 单例
     */
    public static JDBCReadUtils getInstance(String url) {
        if (instance == null) {
            synchronized (JDBCReadUtils.class) {
                if (instance == null) {
                    instance = new JDBCReadUtils(url);
                }
            }
        }
        return instance;
    }
    /**
     * 查询（返回Array结果）
     */
    private Object[] queryArray(String sql, Object... params) {
        Object[] result = null;
        try {
            result = runner.query(sql, new ArrayHandler(), params);
        } catch (SQLException e) {
            logger.error(e.getMessage());
        }
        return result;
    }
    /**
     * 查询（返回ArrayList结果）
     */
    public List<Object[]> queryArrayList(String sql, Object... params) {
        List<Object[]> result = null;
        try {
            result = runner.query(sql, new ArrayListHandler(), params);
        } catch (SQLException e) {
            logger.error(e.getMessage());
        }
        return result == null ? new ArrayList<>() : result;
    }
    /**
     * 更新（包括UPDATE、INSERT、DELETE，返回受影响的行数）
     */
    public int update(String sql, Object... params) {
        int result = 0;
        try {
            result = runner.update(sql, params);
        } catch (SQLException e) {
            logger.error(e.getMessage());
        }
        return result;
    }
}

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://singleNode:3306/spark?useSSL=false&createDatabaseIfNotExist=true&characterEncoding=UTF-8
username=root
password=root

package cn.kgc;
import cn.kgc.utils.JDBCReadUtils;
import java.util.List;
public class Test {
    public static void main(String[] args) {
        List<Object[]> result = JDBCReadUtils.getInstance("C:\\Users\\Administrator\\Desktop\\总部实战课\\spark\\project\\src\\main\\resources\\jdbc.properties")
                .queryArrayList("select * from entity_question_number_accuracy limit 10;");
        for (Object o[] : result) {
            System.out.println(o[0] + "\t" + o[1] + "\t" + o[2] + "\t" + o[3]);
        }
    }
}