Java的JDBC使用

package com.fd.jdbc;

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

public class JDBCDemo01 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Connection conn = null;
        try {
            //加载驱动类
            Class.forName("com.mysql.jdbc.Driver");
            //建立连接
            long start = System.currentTimeMillis();
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/iot", "root", "root");
            long end = System.currentTimeMillis();
            System.out.println("end - start = " + (end - start) + "ms");
            Statement state = conn.createStatement();
            ResultSet result = state.executeQuery("select * from user");
            while(result.next()) {
                System.out.println(result.getInt(1) + " " + result.getString(2) + " " + result.getString(3));
            }
            
            result.close();
            
            //createStatement 会有sql注入问题
            //PreparedStatement 可以
            PreparedStatement pStatement = conn.prepareStatement("delete from user where id = ?");
            pStatement.setInt(1, 3);
            pStatement.executeUpdate();
            conn.close();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            try {
　　　　　　　　　　if(conn != null)
                　　conn.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

}