Java_JDBC_连接池封装调用实例

版权声明：本文为博主原创文章，随便转载。 https://blog.csdn.net/qq_36107346/article/details/83508785

需要到mysql官网下载相对应版本的mysql-connector-java-5.1.47.jar
连接类库封装：

package cn.itcasst.ws.mysqldb;

import java.io.FileInputStream;
import java.io.IOException;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * 数据库连接类 说明:封装了 无参，有参，存储过程的调用
 * 
 * @author
 *
 */
public class ConnectionDB {

	/**
	 * 数据库驱动类名称 com.microsoft.sqlserver.jdbc.SQLServerDriver
	 */
	private static String DRIVER;

	/**
	 * 连接字符串 jdbc:sqlserver://localhost:1433; databaseName=Northwind
	 */
	private static String URLSTR;

	/**
	 * 用户名
	 */
	private static String USERNAME;

	/**
	 * 密码
	 */
	private static String USERPASSWORD;

	/**
	 * 创建数据库连接对象
	 */
	private Connection connnection = null;

	/**
	 * 创建PreparedStatement对象
	 */
	private PreparedStatement preparedStatement = null;

	/**
	 * 创建CallableStatement对象
	 */
	private CallableStatement callableStatement = null;
	private static Properties p = new Properties();
	/**
	 * 创建结果集对象
	 */

	private ResultSet resultSet = null;

	static {

		try {
			FileInputStream fis = new FileInputStream(
					Thread.currentThread().getContextClassLoader().getResource("db.properties").getPath());
			p.load(fis);
			DRIVER = p.getProperty("driver");
			URLSTR = p.getProperty("url");
			USERNAME = p.getProperty("user");
			USERPASSWORD = p.getProperty("pass");
			Class.forName(DRIVER);

			fis.close();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}

	// static {
	// try {
	// // 加载数据库驱动程序
	// Class.forName(DRIVER);
	// } catch (ClassNotFoundException e) {
	// System.out.println("加载驱动错误");
	// System.out.println(e.getMessage());
	// }
	// }

	/**
	 * 建立数据库连接
	 * 
	 * @return 数据库连接
	 */
	public Connection getConnection() {
		try {
			// 获取连接
			connnection = DriverManager.getConnection(URLSTR, USERNAME, USERPASSWORD);
		} catch (SQLException e) {
			System.out.println(e.getMessage());
		}
		return connnection;
	}

	/**
	 * insert update delete SQL语句的执行的统一方法
	 * 
	 * @param sql
	 *            SQL语句
	 * @param params
	 *            参数数组，若没有参数则为null
	 * @return 受影响的行数
	 */
	public int executeUpdate(String sql, Object[] params) {
		// 受影响的行数
		int affectedLine = 0;

		try {
			// 获得连接
			connnection = this.getConnection();
			// 调用SQL
			preparedStatement = connnection.prepareStatement(sql);

			// 参数赋值
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					preparedStatement.setObject(i + 1, params[i]);
				}
			}

			// 执行
			affectedLine = preparedStatement.executeUpdate();

		} catch (SQLException e) {
			System.out.println(e.getMessage());
		} finally {
			// 释放资源
			closeAll();
		}
		return affectedLine;
	}

	/**
	 * SQL 查询将查询结果直接放入ResultSet中
	 * 
	 * @param sql
	 *            SQL语句
	 * @param params
	 *            参数数组，若没有参数则为null
	 * @return 结果集
	 */
	private ResultSet executeQueryRS(String sql, Object[] params) {
		try {
			// 获得连接
			connnection = this.getConnection();

			// 调用SQL
			preparedStatement = connnection.prepareStatement(sql);

			// 参数赋值
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					preparedStatement.setObject(i + 1, params[i]);
				}
			}

			// 执行
			resultSet = preparedStatement.executeQuery();

		} catch (SQLException e) {
			System.out.println(e.getMessage());
		}

		return resultSet;
	}

	/**
	 * SQL 查询将查询结果：一行一列
	 * 
	 * @param sql
	 *            SQL语句
	 * @param params
	 *            参数数组，若没有参数则为null
	 * @return 结果集
	 */
	public Object executeQuerySingle(String sql, Object[] params) {
		Object object = null;
		try {
			// 获得连接
			connnection = this.getConnection();

			// 调用SQL
			preparedStatement = connnection.prepareStatement(sql);

			// 参数赋值
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					preparedStatement.setObject(i + 1, params[i]);
				}
			}

			// 执行
			resultSet = preparedStatement.executeQuery();

			if (resultSet.next()) {
				object = resultSet.getObject(1);
			}

		} catch (SQLException e) {
			System.out.println(e.getMessage());
		} finally {
			closeAll();
		}

		return object;
	}

	/**
	 * 获取结果集，并将结果放在List中
	 * 
	 * @param sql
	 *            SQL语句
	 * @return List 结果集
	 */
	public List<Object> excuteQuery(String sql, Object[] params) {
		// 执行SQL获得结果集
		ResultSet rs = executeQueryRS(sql, params);

		// 创建ResultSetMetaData对象
		ResultSetMetaData rsmd = null;

		// 结果集列数
		int columnCount = 0;
		try {
			rsmd = rs.getMetaData();

			// 获得结果集列数
			columnCount = rsmd.getColumnCount();
		} catch (SQLException e1) {
			System.out.println(e1.getMessage());
		}

		// 创建List
		List<Object> list = new ArrayList<Object>();

		try {
			// 将ResultSet的结果保存到List中
			while (rs.next()) {
				Map<String, Object> map = new HashMap<String, Object>();
				for (int i = 1; i <= columnCount; i++) {
					map.put(rsmd.getColumnLabel(i), rs.getObject(i));
				}
				list.add(map);
			}
		} catch (SQLException e) {
			System.out.println(e.getMessage());
		} finally {
			// 关闭所有资源
			closeAll();
		}

		return list;
	}

	/**
	 * 存储过程带有一个输出参数的方法
	 * 
	 * @param sql
	 *            存储过程语句
	 * @param params
	 *            参数数组
	 * @param outParamPos
	 *            输出参数位置
	 * @param SqlType
	 *            输出参数类型
	 * @return 输出参数的值
	 */
	public Object excuteQuery(String sql, Object[] params, int outParamPos, int SqlType) {
		Object object = null;
		connnection = this.getConnection();
		try {
			// 调用存储过程
			callableStatement = connnection.prepareCall(sql);

			// 给参数赋值
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					callableStatement.setObject(i + 1, params[i]);
				}
			}

			// 注册输出参数
			callableStatement.registerOutParameter(outParamPos, SqlType);

			// 执行
			callableStatement.execute();

			// 得到输出参数
			object = callableStatement.getObject(outParamPos);

		} catch (SQLException e) {
			System.out.println(e.getMessage());
		} finally {
			// 释放资源
			closeAll();
		}

		return object;
	}

	/**
	 * 关闭所有资源
	 */
	private void closeAll() {
		// 关闭结果集对象
		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				System.out.println(e.getMessage());
			}
		}

		// 关闭PreparedStatement对象
		if (preparedStatement != null) {
			try {
				preparedStatement.close();
			} catch (SQLException e) {
				System.out.println(e.getMessage());
			}
		}

		// 关闭CallableStatement 对象
		if (callableStatement != null) {
			try {
				callableStatement.close();
			} catch (SQLException e) {
				System.out.println(e.getMessage());
			}
		}

		// 关闭Connection 对象
		if (connnection != null) {
			try {
				connnection.close();
			} catch (SQLException e) {
				System.out.println(e.getMessage());
			}
		}
	}
}

同级文件夹下面的 db.properties

driver=com.mysql.jdbc.Driver

#db.url=jdbc:mysql://192.1.1.1:3306/mmall?characterEncoding=utf-8
#test 为mysql中的一个数据库名称
url=jdbc:mysql://localhost:3306/test
user=root
pass=###

import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

public class mysqlTest {
	@SuppressWarnings("unchecked")
	public static void main(String[] args) {

		ConnectionDB BM = new ConnectionDB();
		// 插入
//	  int count = BM.executeUpdate("insert into u_user (name,age)values('新添加name','19')",null);
			  
		//查询多条
		List<Object> list = BM.excuteQuery("select * from u_user limit 2 ", null);
		//强转 List<String> 类型
//		List<String> list = (List<String>)(List)listo;
		
		//一种遍历方式
//		for (Iterator iter = list.iterator(); iter.hasNext();) {
//			Object object = (Object) iter.next();
//			@SuppressWarnings("unchecked")
//			HashMap<String, Object> objects= (HashMap<String, Object>)object;
//			for (String key : objects.keySet()) {
//				System.out.println("key= "+ key + " and value= " + objects.get(key));
//			}
//		}
	
		//另一种遍历方式
        Iterator<Object> iterator=  list.iterator();
        while (iterator.hasNext()) {
			Object object = (Object) iterator.next();
			HashMap<String, Object> objects= (HashMap<String, Object>)object;
			for (String key : objects.keySet()) {
				System.out.println("key= "+ key + " and value= " + objects.get(key));
				break;
			}
		}

		//查询是否存在数据返回integer
		Object object= BM.executeQuerySingle("select name from u_user where age='22' ",null);
		System.out.println(object);

		System.out.println("over");
	}
}

返回结果：

key= sex and value= 女
key= sex and value= 男
王二
over