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這是什么錯(cuò)誤?代碼都是按照老師寫的
2017-07-24
源自:Spring入門篇 4-2
正在回答
如果自行撰寫了構(gòu)造函數(shù),編譯程序就不會(huì)自動(dòng)建立默認(rèn)構(gòu)造函數(shù),所以會(huì)初始化失敗。在private InjectionDAO injectionDAO上 或者 setter上@Autowired的話,而且撰寫的帶參構(gòu)造函數(shù)沒有注釋掉,前兩者就沒有默認(rèn)構(gòu)造函數(shù)來調(diào)用形成實(shí)例對(duì)象了,所以報(bào)錯(cuò)里頭會(huì)有說no default constructor 還有 initialization失敗
復(fù)制粘貼就是容易錯(cuò)。。。
@Autowired
private InjectionDAO injectionDAO;
//設(shè)置注入
public void setInjectionDAO(InjectionDAO injectionDAO) {
this.injectionDAO = injectionDAO;
}
//構(gòu)造器注入
? ? public InjectionServiceImpl(InjectionDAO injectionDAO){
? ? this.injectionDAO=injectionDAO;
? ? }
三個(gè)共存就會(huì)報(bào)錯(cuò),除非注解在set或構(gòu)造函數(shù)上,不懂得為什么?
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2017-12-02
如果自行撰寫了構(gòu)造函數(shù),編譯程序就不會(huì)自動(dòng)建立默認(rèn)構(gòu)造函數(shù),所以會(huì)初始化失敗。在private InjectionDAO injectionDAO上 或者 setter上@Autowired的話,而且撰寫的帶參構(gòu)造函數(shù)沒有注釋掉,前兩者就沒有默認(rèn)構(gòu)造函數(shù)來調(diào)用形成實(shí)例對(duì)象了,所以報(bào)錯(cuò)里頭會(huì)有說no default constructor 還有 initialization失敗
2017-07-25
復(fù)制粘貼就是容易錯(cuò)。。。
@Autowired
private InjectionDAO injectionDAO;
//設(shè)置注入
public void setInjectionDAO(InjectionDAO injectionDAO) {
this.injectionDAO = injectionDAO;
}
//構(gòu)造器注入
? ? public InjectionServiceImpl(InjectionDAO injectionDAO){
? ? this.injectionDAO=injectionDAO;
? ? }
三個(gè)共存就會(huì)報(bào)錯(cuò),除非注解在set或構(gòu)造函數(shù)上,不懂得為什么?