JDBC浅析

今天简单的说一下jdbc,本来这玩意儿也很简单。

大家只需要记住其中的几个重要的类就行了，它们都在sql包里。今天主要是拿mysql来连接。先看一下主要的几个类吧。

1.Conenction

2.Statement

3.ResultSet

废话不多说我直接上代码了，因为实在很简单

import java.sql.*;

//Java DataBase Connectivity
public class Main {

	public static void main(String[] args) {

	}
}

class Init{
	//用于连接的账号和密码
	private String user;
	private String passw;
	private String protocol;

	//收集statement connenction resultset的对象方便清理
	private Statement statement = null;
	private Connection connection = null;
	private ResultSet resultset = null;

	public String getUser() {
		return user;
	}

	public void setUser(String user) {
		this.user = user;
	}

	public String getPassw() {
		return passw;
	}

	public void setPassw(String passw) {
		this.passw = passw;
	}

	public String getProtocol() {
		return protocol;
	}

	public void setProtocol(String protocol) {
		this.protocol = protocol;
	}

	//返回一个connection引用的方法
	public Connection getConnection() throws ClassNotFoundException{
		//利用反射动态加载Driver
		Class.forName("com.mysql.jdbc.Driver");
		//返回一个Connection对象
		Connection connection = null;
		try {
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/student",user,passw);
		} catch (SQLException e) {
			//捕获打印异常栈
			e.printStackTrace();
		}
		return connection;
	}

	//返回一个Statement的对象
	public Statement getStatement(){
		Statement statement = null;
		try {
			statement = getConnection().createStatement();
		} catch (ClassNotFoundException | SQLException e) {
			//捕获打印异常栈
			e.printStackTrace();
		}
		return statement;
	}

	//对表进行增加数据的操作
	public void IDU(String s){
		//statement 被调用返回给字段statement
		if(statement == null){
			statement = getStatement();
		}

		try {
			statement.executeUpdate(s);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		finally{
			clear();
		}
	}

	//表的查询
	public void queryData(String s){
		if(statement == null){
			statement = getStatement();
		}
		try {
			resultset = statement.executeQuery(s);
			ResultSetMetaData rsmd = resultset.getMetaData();
			//获取字段长度
			int count = rsmd.getColumnCount();
			//遍历数据
			while(resultset.next()){
				for(int i = 1;i<= count;i++){
					System.out.println(resultset.getObject(i));
				}
			}
		} catch (SQLException e) {
			//打印异常栈
			e.printStackTrace();
		}
		finally{
			clear();
		}
	}

	//对各个占用资源的类进行清理
	public void clear(){
		try{
			if(statement != null){
				statement.close();
			}
			if(connection != null){
				connection.close();
			}
			if(resultset != null){
				resultset.close();
			}
		}
		catch(Exception e){
			e.printStackTrace();
		}
	}
}

相信大家都能看懂，哪里不懂或者是哪里有错误请在回复区指出。