Java Jdbc知识回顾(一)

主要方面

创建jdbc步骤

• 加载驱动Class.forname()
• 获得连接Connection
• 获得Statement(PreparedStatement)对象,执行SQL语句
• 返回ResultSet结果,封装实体对象
• 关闭结果

Statement和PreparedStatement区别

• PreparedStatement可以防止参数注入,Statement不能防止
• PreparedStatement对象防止sql注入的方式是把用户非法输入的单引号用\反斜杠做了转义，从而达到了防止sql注入的目的

测试代码

package com;
import java.sql.*;

/**
 * Hello world!
 */
public class App 
{
    public static void main( String[] args ) throws Exception{

        query_Statement();
        query_PreparedStatement();
    }

    /**
     * Statement查询
     * @throws Exception
     */
    public static void query_Statement() throws Exception{
        Class.forName("com.mysql.cj.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/study?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true&useSSL=false", "root", "123456");
        Statement statement = connection.createStatement();
        String sql = "select * from test_jbdc where id =1";
        ResultSet rs = statement.executeQuery(sql);
        while (rs.next()){
            int id = rs.getInt("id");
            String name = rs.getString("name");
            String address = rs.getString("address");
            int age = rs.getInt("age");
            System.out.println("id:"+id);
            System.out.println("name:"+name);
            System.out.println("address:"+address);
            System.out.println("age:"+age);
        }
        rs.close();
        statement.close();
        connection.close();
    }

    /**
     * PreparedStatment查询
     * @throws Exception
     */
    public static void query_PreparedStatement() throws Exception{
        Class.forName("com.mysql.cj.jdbc.Driver");
        Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/study?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true&useSSL=false", "root", "123456");
        String sql = "select * from test_jbdc where id =?";
        PreparedStatement psmt = connection.prepareStatement(sql);
        psmt.setInt(1,1);
        ResultSet rs = psmt.executeQuery();
        while (rs.next()){
            int id = rs.getInt("id");
            String name = rs.getString("name");
            String address = rs.getString("address");
            int age = rs.getInt("age");
            System.out.println("id:"+id);
            System.out.println("name:"+name);
            System.out.println("address:"+address);
            System.out.println("age:"+age);
        }
        rs.close();
        psmt.close();
        connection.close();
    }
}

测试结果