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這篇文章主要介紹“Mybatis中#和$的區(qū)別是什么”,在日常操作中,相信很多人在Mybatis中#和$的區(qū)別是什么問(wèn)題上存在疑惑,小編查閱了各式資料,整理出簡(jiǎn)單好用的操作方法,希望對(duì)大家解答”Mybatis中#和$的區(qū)別是什么”的疑惑有所幫助!接下來(lái),請(qǐng)跟著小編一起來(lái)學(xué)習(xí)吧!
<select id="selectUser" resultMap="BaseResultMap"> SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name like #{userName} </select>
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("用戶(hù)名:"+u.getUserName()); } }else{ System.out.println("暫無(wú)數(shù)據(jù)"); }
sql打印:
Preparing: SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = ?
Parameters: wanglingzhi(String)
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("用戶(hù)名:"+u.getUserName()); } }else{ System.out.println("暫無(wú)數(shù)據(jù)"); }
sql打?。?/p>
Preparing: SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = ?
Parameters: wanglingzhi or acc.user_name = shuizhong(String)
<select id="selectUser" resultMap="BaseResultMap"> SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name like ${userName} </select>
DfwsSysUserAccount user = new DfwsSysUserAccount(); user.setUserName("'wanglingzhi'"); List<DfwsSysUserAccount> list = userAccountService.selectUser(user); if(list!=null && list.size()>0){ for (DfwsSysUserAccount u:list) { System.out.println("用戶(hù)名:"+u.getUserName()); } }else{ System.out.println("暫無(wú)數(shù)據(jù)"); }
打印sql:
SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = 'wanglingzhi'
DfwsSysUserAccount user = new DfwsSysUserAccount(); user.setUserName("'wanglingzhi' or acc.user_name = 'shuizhong'"); List<DfwsSysUserAccount> list = userAccountService.selectUser(user); if(list!=null && list.size()>0){ for (DfwsSysUserAccount u:list) { System.out.println("用戶(hù)名:"+u.getUserName()); } }else{ System.out.println("暫無(wú)數(shù)據(jù)"); }
打印sql:
SELECT acc.user_name FROM dfws_sys_user_account AS acc WHERE acc.user_name = 'wanglingzhi' or acc.user_name = 'shuizhong'
很顯然,這里已經(jīng)sql注入了。
總結(jié)下,一般說(shuō)來(lái),二者的區(qū)別可總結(jié)為以下6點(diǎn):
(1)#將傳入的數(shù)據(jù)都當(dāng)成一個(gè)字符串,會(huì)對(duì)自動(dòng)傳入的數(shù)據(jù)加一個(gè)雙引號(hào)。如:order by #user_id#,如果傳入的值是111,那么解析成sql時(shí)的值為order by "111",如果傳入的值是id,則解析成的sql為order by "id"。
(2)$將傳入的數(shù)據(jù)直接顯示生成在sql中。如:order by $user_id$,如果傳入的值是111,那么解析成sql時(shí)的值為order by user_id, 如果傳入的值是id,則解析成的sql為order by id。
(3)#方式在很大程度上能夠防止sql注入。
(4)$方式無(wú)法防止sql注入。
(5)$方式一般用于傳入數(shù)據(jù)庫(kù)對(duì)象,例如傳入表名。
(6)一般能用#的就別用$。
ps:在使用mybatis中還遇到<![CDATA[]]>的用法,在該符號(hào)內(nèi)的語(yǔ)句,將不會(huì)被當(dāng)成字符串來(lái)處理,而是直接當(dāng)成sql語(yǔ)句,比如要執(zhí)行一個(gè)存儲(chǔ)過(guò)程。
到此,關(guān)于“Mybatis中#和$的區(qū)別是什么”的學(xué)習(xí)就結(jié)束了,希望能夠解決大家的疑惑。理論與實(shí)踐的搭配能更好的幫助大家學(xué)習(xí),快去試試吧!若想繼續(xù)學(xué)習(xí)更多相關(guān)知識(shí),請(qǐng)繼續(xù)關(guān)注億速云網(wǎng)站,小編會(huì)繼續(xù)努力為大家?guī)?lái)更多實(shí)用的文章!
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