dbconnect.java

用Java WEB写的图书管理系统

package book;

import java.sql.*;

public class DbConnect {
	// db用户名
	private final static String userName = "root";
	// db密码
	private final static String password = "123";
	// db驱动程序
	private final static String driverClass = "com.mysql.jdbc.Driver";
	// db名称
	private final static String dbName = "book";
	// db的URL
	private static String url = "jdbc:mysql://localhost:3306/" + dbName
			+ "?useUnicode=true&characterEncoding=gb2312";

	private static Connection conn = null;

	private static Statement stmt = null;

	// 连接数据库，加载此类是自动连接，且只连接一次
	static {
		try {
			Class.forName(driverClass);
			conn = DriverManager.getConnection(url, userName, password);
			stmt = conn.createStatement();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	// 插入、修改、删除数据操作
	public static int update(String sql) {
		// 得到数据改变的行的数目
		int num = 0;
		try {
			num = stmt.executeUpdate(sql);
		} catch (SQLException e) {
			e.printStackTrace();
		}

		return num;
	}

	// 查询数据，返回数据集
	public static ResultSet query(String sql) {
		ResultSet rs = null;
		try {
			rs = stmt.executeQuery(sql);
		} catch (SQLException e) {
			e.printStackTrace();
		}

		return rs;
	}

	// 关闭数据库连接
	public static void close() {
		try {
			stmt.close();
			conn.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}