一、JDBC连接流程

下载相应的jar包或者使用Maven注入依赖
注册加载一个驱动
创建数据库连接（Connection）
构造SQL语句
创建statement，发送sql语句
执行sql语句
处理sql结果
关闭statement和connection

二、相应的依赖以及数据库准备

1.数据库的创建

#可以将本代码放入一个create,sql文件，执行下面的操作。（sql脚本的执行）

 # 创建数据库
create database managelibrary;
user managelibrary;
# 创建表
create table if not exists `user`(
    `id` int unsigned auto_increment,
    `name` varchar(11) not null,
    `sid` varchar(11) not null,
    `num` varchar(11) not null,
    `password` varchar(11) not null,
    `telphone` varchar(11),
    primary key(`id`)
)engine=InnoDB Default charset=utf8;

使用 \. D:create.sql 或者 source \D:create.sql 可以直接创建

2.maven依赖

    <!--mysql包括c3p0和mysql的java连接器-->
 <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.47</version>
    </dependency>
    <dependency>
			<groupId>c3p0</groupId>
			<artifactId>c3p0</artifactId>
			<version>0.9.1.2</version>
		</dependency>

三、具体语句

注册加载驱动

Class.forName("com.mysql.jdbc.Driver");	//使用mysql的驱动;

创建一个连接

Connection connection = DriverManager.getConnection("jdbc://ip地址:端口号/数据库名称“，“用户名”,"密码");

构造sql语句基本sql语句

例如
//插入
insert into user(name, sid, password, telphone, num) values(?,?,?,?,?);//问号表示位置参数
//删除
delete from user where name = '';
//查找
select * from user where name = '';

prepareStatement的准备
执行

//执行查找
stmt.executeQuery();
//执行更新
stmt.executeUpdate();

6.处理查找结果

ResultSet resultset = statement.executeQuery();

四、实例

实体文件
基本属性 + 构造器 + set,get + toString方法

	private int id;
	private String name;
	private String password;
	private String Sid;
	private String telphone;
	private String num;

配置文件 jdbc.properties

需要放在classpath路径下

driver=com.mysql.jdbc.Driver         #如果版本较高可以使用com.cj.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/managelibrary?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8&useSSL=false
#这里指定了字符编码和解码格式，时区，是否加密传输
username=root
password=roto

JdbcUtil文件

//如果从properties中获取配置信息可以这么写,第一次尝试可以直接下面的写法
	private Properties properties;
	public Connection getCon() throws ClassNotFoundException, SQLException, IOException {
		properties = new Properties();
		InputStream in = JdbcUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");//获取配置文件中的内容
		properties.load(in);
   	    String driver = properties.getProperty("driver");
   	    String url = properties.getProperty("url");
   	    String username = properties.getProperty("username");
   	    String password = properties.getProperty("password");
		Class.forName("com.mysql.jdbc.Driver");
   	 	Connection connection = DriverManager.getConnection(url,username , password);
   	 	return connection;
    }

public class JdbcUtil {
     // 1.驱动获取 2.连接数据库 
	public Connection getCon() throws ClassNotFoundException, SQLException {
   	 Class.forName("com.mysql.jdbc.Driver");
   	 Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/ManageLibrary", "root", "1230");
   	 return connection;
    }
    
    //根据姓名查找
    public ResultSet findByName(String username) throws SQLException, ClassNotFoundException {
      	 String sql = "select * from user where name = ?"; //3.构造查找的sql
       	 Connection connection = getCon();					  
       	 PreparedStatement statement = (PreparedStatement) connection.prepareStatement(sql);
       	 statement.setString(1, username);              //4.statement的准备
       	 ResultSet resultset = statement.executeQuery();//5.执行sql的语句

       	 return resultset;
    }
    
    //插入用户
    public boolean insertUser(user user) throws ClassNotFoundException, SQLException {
   	 Connection connection =getCon();
   	 String sql = "insert into user(name, sid, password, telphone, num) values(?,?,?,?,?)";
  
	 PreparedStatement psmt = (PreparedStatement) connection.prepareStatement(sql);
	   psmt.setString(1, user.getName());
       psmt.setString(2, user.getSid());
       psmt.setString(3,user.getPassword());
       psmt.setString(4, user.getTelphone());
       psmt.setInt(5, user.getNum());
       psmt.executeUpdate();
       //用来判断是否插入成功，成功可以从数据库中找到
       ResultSet resultSet = findByName(user.getName());
       boolean flag = false;
       while(resultSet.next()) {
    	  flag = true;
       }
       return flag;
    }
   
    
    //判断用户名和密码是否匹配，这个应该放在service层
    public boolean checkUser(String username,String password) throws Exception {
			
    	Connection connection = getCon();
    	String sql = "select * from user where name = ? and password = ?";
    	PreparedStatement psmt = connection.prepareStatement(sql);
    	psmt.setString(1, username);
    	psmt.setString(2, password);
    	ResultSet resultSet = psmt.executeQuery();
		boolean flag = false;
		while(resultSet.next()) {
			flag = true;
		}
		return flag;
    }
    
    //根据姓名进行删除
    public boolean delete(String username,String Sid) throws SQLException, ClassNotFoundException {
		Connection connection = getCon();
		String sql =  "delete from user where name = ?";
		PreparedStatement pmst = connection.prepareStatement(sql);
		pmst.setString(1, username);
		pmst.executeUpdate();
		//判断删除是否成功
		ResultSet resultSet = findByName(username);
		boolean flag = true;
		while(resultSet.next()) {
			flag = false;
		}
		return flag;
    }
}

测试文件

public class Main {
	public static void main(String[] args) throws ClassNotFoundException, SQLException {
		//testInser();
		//testDelete();
		testFindByName("kk");
	}
	//检测插入
	static void testInser() throws ClassNotFoundException, SQLException {
		JdbcUtil jdbcdemo = new JdbcUtil();
		user user = new user("","","","","");
        if(jdbcdemo.insertUser(user)) {
        	System.out.println("插入成功");
        }
        else System.out.println("无效注册");
	}
	
	//检测根据姓名查找
	static void testFindByName(String name) throws SQLException, ClassNotFoundException {
		
		JdbcUtil jdbcUtil = new JdbcUtil();
        ResultSet resultSet = jdbcUtil.findByName(name);
        boolean flag = true;
		while(resultSet.next()){
			flag = false;
    		System.out.println("查找信息如下");
    		user user2 = new user(resultSet.getInt(1),
    				resultSet.getString(2),
    		   resultSet.getString(3),
			   resultSet.getString(4),
			   resultSet.getString(5),
					resultSet.getString(6));
    		System.out.println(user2.toString());
    	}
		if(flag) System.out.println("没有此人！");
	}
	
	//检测姓名和密码是否对应
	static void testCheck() throws Exception {
		JdbcUtil jdbcUtil = new JdbcUtil();
		if(jdbcUtil.checkUser("zk", "1234")) {
			testFindByName("zk");
		}
		else System.out.println("账号或密码错误");
		
	}
	
	//检测删除
	static void testDelete() throws ClassNotFoundException, SQLException {
		JdbcUtil jdbcUtil = new JdbcUtil();
		String[] username = {""};
		String[] userpassword = {""};
		for(int i = 0;i < username.length;i++) {
			if(jdbcUtil.delete(username[i],userpassword[i])){
				System.out.println("成功删除" + username[i]);
			}
			else {
				System.out.println( username[i]+"删除失败");
			}
		}
	}
}

五、具体类的总结

具体类	作用
DriverManager	驱动管理器，用于注册驱动，是获取Connection对象的入口
Driver	数据库驱动，用于获取Connection对象
Statement	sql执行器，用于执行sql
ResultSet	结果集，用于封装和操作查询结果
prepareCall	用于调用存储过程

1. PreparedStatement

2. statement

3.Connector

4.Driver

5.ResultSet

六、优化样例代码

1.优化之后可以避免connect的关闭忘记。
2.JbcbUtil设计成静态的使用了单例模式。
3.应该考虑多线程的下的单例问题。

1.jdbcUtil

//使用单例模式进行设计JDBC，没有考虑是否多线程问题
//设计成静态的链接可以避免close的问题
public class JdbcUtil {
	static private Properties properties;

	static public Connection getConnection() throws ClassNotFoundException, SQLException {
		properties = new Properties();
		InputStream in = JdbcUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");//获取配置文件中的内容
   	    try{
			properties.load(in);
		}catch (Exception e){
   	    	e.printStackTrace();
		}
   	    String driver = properties.getProperty("driver");
   	    String url = properties.getProperty("url");
   	    String username = properties.getProperty("username");
   	    String password = properties.getProperty("password");
		Class.forName(driver);
   	 	Connection connection = DriverManager.getConnection(url,username , password);
   	 	return connection;
    }
}

2.userDao

public class UserDao {
    private Connection connection;
    public UserDao(Connection connection){
        this.connection = connection;
    }
    public ResultSet findByName(String username) throws SQLException, ClassNotFoundException {
        String sql = "select * from user where name = ?";
        PreparedStatement statement = (PreparedStatement) connection.prepareStatement(sql);
        statement.setString(1, username);
        ResultSet resultset = statement.executeQuery();
        return resultset;
    }

    public boolean insertUser(user user) throws ClassNotFoundException, SQLException {
        String sql = "insert into user(name, sid, password, telphone, num) values(?,?,?,?,?)";

        PreparedStatement psmt = (PreparedStatement) connection.prepareStatement(sql);
        psmt.setString(1, user.getName());
        psmt.setString(2, user.getSid());
        psmt.setString(3,user.getPassword());
        psmt.setString(4, user.getTelphone());
        psmt.setString(5, user.getNum());
        psmt.executeUpdate();
        ResultSet resultSet = findByName(user.getName());
        boolean flag = false;
        while(resultSet.next()) {
            flag = true;
        }
        return flag;
    }


    public boolean checkUser(String username,String password) throws Exception {
        String sql = "select * from user where name = ? and password = ?";
        PreparedStatement psmt = connection.prepareStatement(sql);
        psmt.setString(1, username);
        psmt.setString(2, password);
        ResultSet resultSet = psmt.executeQuery();
        connection.close();
        boolean flag = false;
        while(resultSet.next()) {
            flag = true;
        }
        return flag;
    }

    public boolean delete(String username,String Sid) throws SQLException, ClassNotFoundException {
        String sql =  "delete from user where name = ?";
        PreparedStatement pmst = connection.prepareStatement(sql);
        pmst.setString(1, username);
        pmst.executeUpdate();
        ResultSet resultSet = findByName(username);
        boolean flag = true;
        while(resultSet.next()) {
            flag = false;
        }
        return flag;
    }
}

3.Main


public class Main {
	static private UserDao userDao;					     //包含了dao和service层的部分实现
	public static void main(String[] args) throws ClassNotFoundException, SQLException {
		userDao = new UserDao(JdbcUtil.getConnection());  //开启连接
		testInser();
		testFindByName("zk");
		testDelete();

	}

	//检测插入
	static void testInser() throws ClassNotFoundException, SQLException {
		user user = new user("zk","1525475","2017","17861401461","46");
        if(userDao.insertUser(user)) {
        	System.out.println("插入成功");
        }
        else System.out.println("无效注册");
	}
	
	//检测根据姓名查找
	static void testFindByName(String name) throws SQLException, ClassNotFoundException {

        ResultSet resultSet = userDao.findByName(name);
        boolean flag = true;
		while(resultSet.next()){
			flag = false;
    		System.out.println("查找信息如下");
    		user user2 = new user(resultSet.getInt(1),
    				resultSet.getString(2),
    		   resultSet.getString(3),
			   resultSet.getString(4),
			   resultSet.getString(5),
					resultSet.getString(6));
    		System.out.println(user2.toString());
    	}
		if(flag) System.out.println("没有此人！");
	}
	
	//检测姓名和密码是否对应
	static void testCheck() throws Exception {
		if(userDao.checkUser("zk", "1234")) {
			testFindByName("zk");
		}
		else System.out.println("账号或密码错误");
		
	}
	
	//检测删除
	static void testDelete() throws ClassNotFoundException, SQLException {
		String[] username = {"zk"};
		String[] userpassword = {"201711010416"};
		for(int i = 0;i < username.length;i++) {
			if(userDao.delete(username[i],userpassword[i])){
				System.out.println("成功删除" + username[i]);
			}
			else {
				System.out.println( username[i]+"删除失败");
			}
		}
	}
}

Java学习之JDBC连接mysql

这里写目录标题

一、JDBC连接流程

二、相应的依赖以及数据库准备

1.数据库的创建

2.maven依赖

三、具体语句

四、实例

五、具体类的总结

1. PreparedStatement

2. statement

3.Connector

4.Driver

5.ResultSet

六、优化样例代码

1.jdbcUtil

2.userDao

3.Main

七、JDBC底层的实现

八、一些问题

1. 关于mysql

2. 关于JDBC#

九、相关信息

猜你喜欢