SQL注入问题

sql注入问题

sql存在漏洞，会被攻击导致数据泄露 SQL会被拼接 or

package com.xy.MySQL;

import com.xy.MySQL.myMethods.JDBCUtils;

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

/**
 * @ClassName: SQLQuestion
 * @Description: TODO 类描述
 * @Version: 1.0
 */

public class SQL注入漏洞测试 {
    public static void main(String[] args) {

        //正常登录
//        login("张三","1234567");

        //sql注入
        login("' or '1=1","' or '1=1"); //这里用这种方法获取到了不应该获取到的信息

    }

    /**
     * 登录业务
     */
    public static void login(String userName, String password) {
        Connection con = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            con = JDBCUtils.getConnection();
            st = con.createStatement();
            String sql = "SELECT * FROM users WHERE `name`='"+userName+"' AND `password`='"+password+"'";
            // SELECT * FROM users WHERE `name`='' or '1=1' AND `password`='123456'
            System.out.println(sql);
            rs = st.executeQuery(sql);
            while (rs.next()) {
                System.out.println("id="+rs.getInt("id"));
                System.out.println("name="+rs.getString("name"));
            }

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtils.release(con, st, rs);
        }
    }
}

导致结果：错误的用户名或者密码可以获取到全部的用户信息

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如何防止SQL注入呢？用PreparedStatement对象