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這篇文章主要講解了“super的工作原理是什么”,文中的講解內(nèi)容簡單清晰,易于學(xué)習(xí)與理解,下面請(qǐng)大家跟著小編的思路慢慢深入,一起來研究和學(xué)習(xí)“super的工作原理是什么”吧!
深扒源碼之前,一定要做好參考點(diǎn),這里我們使用類圖來做一個(gè)參考。
super這個(gè)方法對(duì)應(yīng)的代碼并不多,如果我們要去跟的話,只需要仔細(xì)一點(diǎn),了解他的層級(jí)結(jié)構(gòu),基本問題不大。這里把所有源碼都拿出來了
public ClassPathXmlApplicationContext(ApplicationContext parent) { super(parent); } public AbstractXmlApplicationContext(@Nullable ApplicationContext parent) { super(parent); } public AbstractRefreshableConfigApplicationContext(@Nullable ApplicationContext parent) { super(parent); } public AbstractRefreshableApplicationContext(@Nullable ApplicationContext parent) { super(parent); } public AbstractApplicationContext(@Nullable ApplicationContext parent) { this(); this.setParent(parent); } public AbstractApplicationContext() { this.resourcePatternResolver = getResourcePatternResolver(); } protected ResourcePatternResolver getResourcePatternResolver() { return new PathMatchingResourcePatternResolver(this); } public PathMatchingResourcePatternResolver(ResourceLoader resourceLoader) { Assert.notNull(resourceLoader, "ResourceLoader must not be null"); this.resourceLoader = resourceLoader; } public void setParent(@Nullable ApplicationContext parent) { this.parent = parent; if (parent != null) { Environment parentEnvironment = parent.getEnvironment(); if (parentEnvironment instanceof ConfigurableEnvironment) { getEnvironment().merge((ConfigurableEnvironment) parentEnvironment); } } }
從我們的源碼上來看,結(jié)合我們的類圖,不難發(fā)現(xiàn),其實(shí)super(parent)一直在調(diào)用父類的方法,直到AbstractApplicationContext,然后才有真正的操作代碼。
先來看看this(),this()實(shí)際就是我們當(dāng)前類里面的無參構(gòu)造方法,最終其實(shí)也是給我們初始化了一個(gè)ClassPathXmlApplicationContext。這一點(diǎn)我們可以跟一下初始化的代碼
public Resource getResource(String location) { return getResourceLoader().getResource(location); } public Resource getResource(String location) { Assert.notNull(location, "Location must not be null"); for (ProtocolResolver protocolResolver : getProtocolResolvers()) { Resource resource = protocolResolver.resolve(location, this); if (resource != null) { return resource; } } if (location.startsWith("/")) { return getResourceByPath(location); } else if (location.startsWith(CLASSPATH_URL_PREFIX)) { return new ClassPathResource(location.substring(CLASSPATH_URL_PREFIX.length()), getClassLoader()); } else { try { // Try to parse the location as a URL... URL url = new URL(location); return (ResourceUtils.isFileURL(url) ? new FileUrlResource(url) : new UrlResource(url)); } catch (MalformedURLException ex) { // No URL -> resolve as resource path. return getResourceByPath(location); } } }
最終是按照我們的路徑的開頭判斷返回哪種resource
setParent(parent);對(duì)應(yīng)的代碼并不多,也是比較簡單明了的
public void setParent(@Nullable ApplicationContext parent) { this.parent = parent; if (parent != null) { Environment parentEnvironment = parent.getEnvironment(); if (parentEnvironment instanceof ConfigurableEnvironment) { getEnvironment().merge((ConfigurableEnvironment) parentEnvironment); } } }
這幾部代碼就做了一件事情:保存父容器,并將父容器的環(huán)境與當(dāng)前容器環(huán)境合并。
感謝各位的閱讀,以上就是“super的工作原理是什么”的內(nèi)容了,經(jīng)過本文的學(xué)習(xí)后,相信大家對(duì)super的工作原理是什么這一問題有了更深刻的體會(huì),具體使用情況還需要大家實(shí)踐驗(yàn)證。這里是億速云,小編將為大家推送更多相關(guān)知識(shí)點(diǎn)的文章,歡迎關(guān)注!
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