DBUtil工具类

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本文链接： https://blog.csdn.net/YJT180/article/details/99779746

package com.jd.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * 数据库工具类
 * 
 *@author 叶峻韬
 */
public class DBUtil {
	
	/**
	 * 加载驱动
	 */
	static {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	/**
	 *建立连接
	 *
	 *@author 叶峻韬
	 */
	private static Connection getconnection() {
		try {
			String url = PropertiesUtil.getValue("jdbc.url");
			String userName = PropertiesUtil.getValue("jdbc.userName");
			String password = PropertiesUtil.getValue("jdbc.password");
			return DriverManager.getConnection(url, userName, password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 查询数据
	 *
	 *@author 叶峻韬
	 */
	public static boolean select(String sql,IRowMapper rowMapper,Object...params) {
		PreparedStatement prepareStatement=null;
		Connection connection=null;
		try {
			connection=getconnection();
			prepareStatement = connection.prepareStatement(sql);
			for (int i = 1; i <= params.length; i++) {
				prepareStatement.setObject(i, params[i-1]);
			}
			ResultSet resultSet=prepareStatement.executeQuery();
			rowMapper.rowMapper(resultSet);
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			close(prepareStatement, connection);
		}
		return false;
	}
	
	/**
	 * 修改数据
	 *
	 *@author 叶峻韬
	 */
	public static boolean update(String sql,Object...params){
		PreparedStatement prepareStatement=null;
		Connection connection=null;
		try {
			
			connection=getconnection();
			prepareStatement = connection.prepareStatement(sql);
			for(int i=1;i<=params.length;i++) {
				prepareStatement.setObject(i, params[i-1]);
			}
			int effectRows=prepareStatement.executeUpdate();
			return effectRows>0;
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			close(prepareStatement, connection);
		}
		return false;
	}
	
	/**
	 * 判断数据是否存在
	 *
	 *@author 叶峻韬
	 */
	public static boolean exist(String sql,Object...params) {

		class RowMapper implements IRowMapper {
			boolean state;

			@Override
			public void rowMapper(ResultSet resultSet) {
				try {
					state = resultSet.next();
				} catch (SQLException e) {
					e.printStackTrace();
				}

			}

		}
		RowMapper rowMapper = new RowMapper(); // 上转型对象，接口的实现类创建对象，接口不能创建对象。
		select(sql, rowMapper,params);
		return rowMapper.state;
	}
	
	/**
	 * 批量处理
	 *
	 *@author 叶峻韬
	 */
	public static boolean batch(String sql,Object...params) {
		Connection connection=null;
		PreparedStatement prepareStatement=null;
		try {
			connection = getconnection();
			connection.setAutoCommit(false);
			for(int i=0;i<params.length;i++) {
				prepareStatement=connection.prepareStatement(sql);
				for(int j=1;j<=params.length;j++) {
					prepareStatement.setObject(j, params[j-1]);
				}
				prepareStatement.addBatch();
			}
			prepareStatement.executeBatch();
			return true;
		} catch (Exception e) {			
			e.printStackTrace();
			if(connection!=null)
				try {
					connection.rollback();
			} catch (SQLException e1) {
				e1.printStackTrace();
			}finally {
				close(prepareStatement, connection);
			}
		}
		return false;
	}
	
	/**
	 * 释放资源
	 *
	 *@author 叶峻韬
	 */
	private static void close(PreparedStatement prepareStatement, Connection connection) {
		try {
			if (prepareStatement != null) {
				prepareStatement.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		
		try {
			if (connection != null) {
				connection.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
}

package com.jd.util;

import java.sql.ResultSet;

/**
 * 用于重写方法的接口
 * 
 *@author 叶峻韬
 */
public interface IRowMapper{
	void rowMapper(ResultSet resultSet);
}