【Java编程】建立一个简单的JDBC连接-Drivers, Connection, Statement and PreparedStatement

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【Java编程】建立一个简单的JDBC连接-Drivers, Connection, Statement and PreparedStatement

2024-07-04 10:20:57 225人阅读

本blog提供了一个简单的通过JDBC驱动建立JDBC连接例程，并分别通过Statement和PreparedStatement实现对数据库的查询。在下一篇blog中将重点比较Statement与PreparedStatement的差异。

1、为项目添加JDBC驱动

1）JDBC驱动下载

官方下载地址：mysql-connector-java-5.0.8.zip

CSDN资料下载地址：mysql-connector-java-5.0.8.zip

2）为项目添加JDBC驱动

建立项目Java项目JDBCDemo,并在JDBCDemo项目中建立一个lib文件夹，将驱动文件拷贝到lib文件夹，选中驱动文件，右键->BuildPath->Add To Build Path;如图所示：

2、建立db_bbs数据库

1）构建一个数据库db_bbs;

2）执行db_bbs.sql文件的sql语句，在db_bbs数据库中创建user表，并添加数据;

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for `user`
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(10) NOT NULL,
  `password` varchar(10) NOT NULL,
  `gender` varchar(1) NOT NULL,
  `regtime` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=gb2312;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (‘1‘, ‘andy‘, ‘andy‘, ‘1‘, ‘2014-05-13 17:33:28‘);
INSERT INTO `user` VALUES (‘2‘, ‘jack‘, ‘jack‘, ‘1‘, ‘2014-05-14 17:33:55‘);
INSERT INTO `user` VALUES (‘3‘, ‘rose‘, ‘rose‘, ‘0‘, ‘2014-05-13 17:34:36‘);

3、通过属性文件配置数据库

1）属性配置文件db.properties;

#mysql DB properties
DB_DRIVER_CLASS=com.mysql.jdbc.Driver
DB_URL=jdbc:mysql://localhost:3306/db_bbs
DB_USERNAME=root
DB_PASSWORD=root
 
#Oracle DB Properties
#DB_DRIVER_CLASS=oracle.jdbc.driver.OracleDriver
#DB_URL=jdbc:oracle:thin:@localhost:1571:db_bbs
#DB_USERNAME=scott
#DB_PASSWORD=tiger

2）将属性配置文件添加到项目的根目录;

4、建立JDBC连接

package com.andieguo.jdbc;

import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
 * 该类封装了连接和关闭数据库连接操作
 * 
 * @author andieguo
 * 
 */
public class DBConnection {

	public static Connection getConnection() {
		Properties props = new Properties();
		FileInputStream fis = null;
		Connection con = null;
		try {
			fis = new FileInputStream("db.properties");
			props.load(fis);
			// 加载驱动
			Class.forName(props.getProperty("DB_DRIVER_CLASS"));
			// 创建一个连接
			con = DriverManager.getConnection(props.getProperty("DB_URL"), props.getProperty("DB_USERNAME"), props.getProperty("DB_PASSWORD"));
		} catch (IOException | SQLException | ClassNotFoundException e) {
			e.printStackTrace();
		}
		return con;
	}

	// 关闭ResultSet
	public static void closeResultSet(ResultSet rs) {
		if (rs != null) {
			try {
				rs.close();
				rs = null;
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	// 关闭Statement
	public static void closeStatement(Statement stm) {
		if (stm != null) {
			try {
				stm.close();
				stm = null;
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	// 关闭PreparedStatement
	public static void closePreparedStatement(PreparedStatement pstm) {
		if (pstm != null) {
			try {
				pstm.close();
				pstm = null;
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	// 关闭Connection
	public static void closeConnection(Connection con) {
		if (con != null) {
			try {
				con.close();
				con = null;
			} catch (SQLException e) {
				e.printStackTrace();
			}
			con = null;
		}
	}

}

5、使用Statement进行查询

package com.andieguo.jdbc;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

public class DBHelper {

	public static void queryAllByStatement() {
		List<User> users = new ArrayList<User>();
		Connection conn = DBConnection.getConnection();
		Statement stmt = null;
		ResultSet rs = null;
		try {
			stmt = conn.createStatement();
			rs = stmt.executeQuery("select * from user");
			while (rs.next()) {
				User user = new User();
				user.setId(rs.getInt("id"));
				user.setUsername(rs.getString("username"));
				user.setPassword(rs.getString("password"));
				user.setGender(rs.getBoolean("gender"));
				user.setRegtime(rs.getDate("regtime"));
				System.out.println(user.toString());
				users.add(user);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBConnection.closeResultSet(rs);
			DBConnection.closeStatement(stmt);
			DBConnection.closeConnection(conn);
		}
	}

	public static void queryById(Integer id) {
		Connection conn = DBConnection.getConnection();
		Statement stmt = null;
		ResultSet rs = null;
		try {
			stmt = conn.createStatement();
			rs = stmt.executeQuery("select * from user where id = " + id);
			while (rs.next()) {
				User user = new User();
				user.setId(rs.getInt("id"));
				user.setUsername(rs.getString("username"));
				user.setPassword(rs.getString("password"));
				user.setGender(rs.getBoolean("gender"));
				user.setRegtime(rs.getDate("regtime"));
				System.out.println(user.toString());
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBConnection.closeResultSet(rs);
			DBConnection.closeStatement(stmt);
			DBConnection.closeConnection(conn);
		}
	}


}

6、使用PreparedStatement进行查询

package com.andieguo.jdbc;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class DBHelper {

	public static void queryAllByprepareStatement() {
		List<User> users = new ArrayList<User>();
		Connection conn = DBConnection.getConnection();
		PreparedStatement ps = null;
		ResultSet rs = null;
		try {
			ps = conn.prepareStatement("select * from user");
			rs = ps.executeQuery();
			while (rs.next()) {
				User user = new User();
				user.setId(rs.getInt("id"));
				user.setUsername(rs.getString("username"));
				user.setPassword(rs.getString("password"));
				user.setGender(rs.getBoolean("gender"));
				user.setRegtime(rs.getDate("regtime"));
				System.out.println(user.toString());
				users.add(user);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBConnection.closeResultSet(rs);
			DBConnection.closeStatement(ps);
			DBConnection.closeConnection(conn);
		}
	}

	public static void queryPrepareById(Integer id) {
		Connection conn = DBConnection.getConnection();
		PreparedStatement ps = null;
		ResultSet rs = null;
		try {
			ps = conn.prepareStatement("select * from user where id = ?");
			ps.setInt(1, id);// 设置占位符参数
			rs = ps.executeQuery();
			while (rs.next()) {
				User user = new User();
				user.setId(rs.getInt("id"));
				user.setUsername(rs.getString("username"));
				user.setPassword(rs.getString("password"));
				user.setGender(rs.getBoolean("gender"));
				user.setRegtime(rs.getDate("regtime"));
				System.out.println(user.toString());
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBConnection.closeResultSet(rs);
			DBConnection.closeStatement(ps);
			DBConnection.closeConnection(conn);
		}
	}

}

7、测试用例

package com.andieguo.jdbc;

import junit.framework.TestCase;

public class DBHelperTest extends TestCase {

	public void getConnectionTest(){
		System.out.println(DBConnection.getConnection());
	}
	
	public void queryAllByStatementTest(){
		DBHelper.queryAllByStatement();
	}
	
	public void queryAllByprepareStatementTest(){
		DBHelper.queryAllByprepareStatement();
	}
	
	public void queryByIdTest(){
		DBHelper.queryById(2);
	}
	
	public void queryByPrepareIdTest(){
		DBHelper.queryPrepareById(3);
	}
	
}

8、参考

JDBC Example Tutorial – Drivers, Connection, Statement and ResultSet（推荐）

Java code for connecting Mysql database and using Arraylist type

9、你可能感兴趣的

【Java编程】写入、读取、遍历Properties文件

转载请注明出处：http://blog.csdn.net/andie_guo/article/details/25737031,谢谢！

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