jdbc连接数据库封装的代码

package com.weihai.conn;

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

public class DBconn {
	public static final String dbDriver="com.mysql.jdbc.Driver";
	public static final String dbURL="jdbc:mysql://localhost:3306/db_shop?useUnicode=true&characterEncoding=UTF-8&useSSL=false";
	public static final String dbUsername="root";
	public static final String dbPassword="1234";
	public static Connection conn = null;
	public PreparedStatement pt = null;
	public ResultSet rs = null;
	
	
	
	//创建数据库连接
	public static Connection getConntion() {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		try {
			conn = DriverManager.getConnection(dbURL, dbUsername, dbPassword);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
		
	}
	
	
	
	//关闭数据库连接
	public static void close(Connection conn,PreparedStatement pt,ResultSet rs) {
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (pt != null) {
			try {
				pt.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		
	}
	
	public static void close(Connection conn,PreparedStatement pt) {

		if (pt != null) {
			try {
				pt.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		
	}
}

以上封装了连接数据库关闭数据库的代码，在需要的地方直接调用即可

package com.soft1.dao;

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

import com.soft1.bean.User;
import com.weihai.conn.*;

//访问数据库的JavaBean

public class UserDao {
	

	public Connection conn = null;
	public PreparedStatement pt = null;
	public ResultSet rs = null;
	
	
	
    //实现用户名密码验证
	
	public Boolean denglu(String username, String password) {
		Boolean t=false;		     
		conn=DBconn.getConntion();			    
	       String sql="select * from admin_info where name=? and password=?";			
	try {	
		    pt=conn.prepareStatement(sql);
			pt.setString(1, username);
			pt.setString(2, password);
			rs = pt.executeQuery();
			if (rs.next()) {								 
				t= true;
			} else {				
				t=false;
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
	DBconn.close(conn,pt,rs);
		return t;
	}

	
	//查询
	public ArrayList<User> queryAll(){
    	//使用泛型，解决强转的问题
    	ArrayList<User> users = new ArrayList<User>();
		//2.访问数据库，查询用户名密码
		//（1）加载数据库驱动
    	conn=DBconn.getConntion();
		//(3)创建语句容器
		
		String  sql= "select * from admin_info";
		try {
			pt = conn.prepareStatement(sql);
			//(4)执行SQL语句
			 rs = pt.executeQuery();
			//遍历结果集，把结果集转存到users中
			 while(rs.next()){
					//一条记录对应一个User对象
					User user = new User();
					user.setId(rs.getInt("id"));
					user.setUsername(rs.getString(2));
					user.setPassword(rs.getString(3));
					//需要把每个user添加到Users中
					users.add(user);			
			}
		} catch (SQLException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		//关闭数据库连接
		 DBconn.close(conn,pt,rs);
		return users;
    }
	
	//添加
	public boolean insert(User user) {
		boolean t=false;
		conn=DBconn.getConntion();
		String  sql="insert into admin_info(name,password) values(?,?)";
		try {
		pt=conn.prepareStatement(sql);
		pt.setString(1, user.getUsername());
		pt.setString(2, user.getPassword());
		//执行SQL语句
		int i=pt.executeUpdate();
		System.out.println(i);
		
		if(i>0) {
			t=true;
		}
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
		DBconn.close(conn,pt);
		return t;
	}
	}

以上是封装的登录、查询、添加，

从jsp代码中摘出它们有利于提高代码的可读性，修改等操作也会变得方便许多