一篇文章弄懂Mybatis中#和$的区别

来源：jb51　　时间：2021/12/20 15:28:28　　对本文有异议

前言

在学校的时候，想必大家肯定听老师讲过，在mybatis中，配置参数要用#，不要用$符号。因为$不安全，容易被sql注入。讲是这么讲，但是如何注入的，大家一起来看看吧。

一：下面我们写个关于“#”的个sql，看能不能注入。

 <select id="selectUser" resultMap="BaseResultMap">
    SELECT 
    	acc.user_name FROM dfws_sys_user_account AS acc
    WHERE
        acc.user_name like #{userName}
  </select>

1.正常传参

DfwsSysUserAccount user = new DfwsSysUserAccount();
user.setUserName("wanglingzhi");
List<DfwsSysUserAccount> list = userAccountService.selectUser(user);
if(list!=null && list.size()>0){
    for (DfwsSysUserAccount u:list) {
    	System.out.println("用户名："+u.getUserName());
    }
}else{
        System.out.println("暂无数据");
}

sql打印：

Preparing: SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = ??

Parameters: wanglingzhi(String)

2.拼接传参

DfwsSysUserAccount user = new DfwsSysUserAccount();
user.setUserName("'wanglingzhi' or acc.user_name = 'shuizhong'");
List<DfwsSysUserAccount> list = userAccountService.selectUser(user);
if(list!=null && list.size()>0){
    for (DfwsSysUserAccount u:list) {
    	System.out.println("用户名："+u.getUserName());
    }
}else{
        System.out.println("暂无数据");
}

sql打印：

Preparing: SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = ??

Parameters: wanglingzhi or acc.user_name = shuizhong(String)

二：下面我们写个关于“$”的个sql，看能不能注入。

<select id="selectUser" resultMap="BaseResultMap">
    SELECT 
    	acc.user_name FROM dfws_sys_user_account AS acc
    WHERE
        acc.user_name like ${userName}
  </select>

1.正常传参

DfwsSysUserAccount user = new DfwsSysUserAccount();
user.setUserName("'wanglingzhi'");
List<DfwsSysUserAccount> list = userAccountService.selectUser(user);
if(list!=null && list.size()>0){
    for (DfwsSysUserAccount u:list) {
    	System.out.println("用户名："+u.getUserName());
    }
}else{
        System.out.println("暂无数据");
}

打印sql：

SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = 'wanglingzhi'

2.拼接传参

DfwsSysUserAccount user = new DfwsSysUserAccount();
user.setUserName("'wanglingzhi' or acc.user_name = 'shuizhong'");
List<DfwsSysUserAccount> list = userAccountService.selectUser(user);
if(list!=null && list.size()>0){
    for (DfwsSysUserAccount u:list) {
    	System.out.println("用户名："+u.getUserName());
    }
}else{
        System.out.println("暂无数据");
}