咱们上一篇文章最初调用到 `org.springframework.beans.factory.xml. XmlBeanDefinitionReader#doLoadDocument(...)
` 办法，该办法次要代码如下：
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception { //getValidationModeForResource是数据验证模型 return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler, getValidationModeForResource(resource), isNamespaceAware()); }咱们这篇文章次要以 #getValidationModeForResource(...) 办法作为切入，来剖析一下验证模型的次要办法，对于spring中的数据验证、绑定等内容咱们在前面文章一点点的来开掘
1.getValidationModeForResource
/** * 禁止只用验证模型 * Indicates that the validation should be disabled. */ public static final int VALIDATION_NONE = XmlValidationModeDetector.VALIDATION_NONE; /** * 应用自动检测验证模型 * Indicates that the validation mode should be detected automatically. */ public static final int VALIDATION_AUTO = XmlValidationModeDetector.VALIDATION_AUTO; /** * 应用DTD验证模型 * Indicates that DTD validation should be used. */ public static final int VALIDATION_DTD = XmlValidationModeDetector.VALIDATION_DTD; /** * 应用XSD验证模型 * Indicates that XSD validation should be used. */ public static final int VALIDATION_XSD = XmlValidationModeDetector.VALIDATION_XSD; /** * 确定以后 resource资源须要的验证模型 默认主动模式 * 如果显式的配置了验证模型，则用配置的，如果没有则从Resource中来获取 * Determine the validation mode for the specified {@link Resource}. * If no explicit validation mode has been configured, then the validation * mode gets {@link #detectValidationMode detected} from the given resource. * <p>Override this method if you would like full control over the validation * mode, even when something other than {@link #VALIDATION_AUTO} was set. * @see #detectValidationMode */ protected int getValidationModeForResource(Resource resource) { // <1> 获取指定的验证模式 int validationModeToUse = getValidationMode(); // <2> 如果有指定的模式 则间接返回， if (validationModeToUse != VALIDATION_AUTO) { return validationModeToUse; } //<3> 没有指定的 那么通resource中去获取 int detectedMode = detectValidationMode(resource); if (detectedMode != VALIDATION_AUTO) { return detectedMode; } // <4> 若以上都不满足则应用XSD模式 // Hmm, we didn't get a clear indication... Let's assume XSD, // since apparently no DTD declaration has been found up until // detection stopped (before finding the document's root tag). return VALIDATION_XSD; }对上述代码咱们做简略剖析
- <1>处调用
#getValidationMode()办法来获取指定的验证模式 ，这里的validationMode如果是内部手动设置的，那么就间接返回，
/** * Set the validation mode to use. Defaults to {@link #VALIDATION_AUTO}. * <p>Note that this only activates or deactivates validation itself. * If you are switching validation off for schema files, you might need to * activate schema namespace support explicitly: see {@link #setNamespaceAware}. */ public void setValidationMode(int validationMode) { this.validationMode = validationMode; } /** * Return the validation mode to use. */ public int getValidationMode() { return this.validationMode; }- <3>处调用
#detectValidationMode()办法来主动获取验证模型，代码如下：
/** * 进行自动检测指定的XML用那种检测模型 * Detect which kind of validation to perform on the XML file identified * by the supplied {@link Resource}. If the file has a {@code DOCTYPE} * definition then DTD validation is used otherwise XSD validation is assumed. * <p>Override this method if you would like to customize resolution * of the {@link #VALIDATION_AUTO} mode. */ protected int detectValidationMode(Resource resource) { // <1> 资源是否关上 if (resource.isOpen()) { throw new BeanDefinitionStoreException( "Passed-in Resource [" + resource + "] contains an open stream: " + "cannot determine validation mode automatically. Either pass in a Resource " + "that is able to create fresh streams, or explicitly specify the validationMode " + "on your XmlBeanDefinitionReader instance."); } InputStream inputStream; try { inputStream = resource.getInputStream(); } catch (IOException ex) { throw new BeanDefinitionStoreException( "Unable to determine validation mode for [" + resource + "]: cannot open InputStream. " + "Did you attempt to load directly from a SAX InputSource without specifying the " + "validationMode on your XmlBeanDefinitionReader instance?", ex); } try { ////<2> 调用XmlValidationModeDetector 中的实在实现 传入 inputStream return this.validationModeDetector.detectValidationMode(inputStream); } catch (IOException ex) { throw new BeanDefinitionStoreException("Unable to determine validation mode for [" + resource + "]: an error occurred whilst reading from the InputStream.", ex); } }2.detectValidationMode
下面 <3>处调用了 #detectValidationMode() 办法，这里 validationModeDetector 对象是类中的一个不可变成员变量 定义如下：
private final XmlValidationModeDetector validationModeDetector = new XmlValidationModeDetector();#detectValidationMode() 办法的具体实现如下：
/** * 通过指定的 inputStream 来检测 XML 中的验证模型 * Detect the validation mode for the XML document in the supplied {@link InputStream}. * Note that the supplied {@link InputStream} is closed by this method before returning. * @param inputStream the InputStream to parse * @throws IOException in case of I/O failure * @see #VALIDATION_DTD * @see #VALIDATION_XSD */ public int detectValidationMode(InputStream inputStream) throws IOException { //<1> 通过 BufferedReader 读取inputStream // Peek into the file to look for DOCTYPE. BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream)); try { //<2> 是否是DTD验证模式 ，默认否 boolean isDtdValidated = false; String content; // <3> 逐行读取内容 while ((content = reader.readLine()) != null) { content = consumeCommentTokens(content); // <4> 如果是正文或者为空这跳过 if (this.inComment || !StringUtils.hasText(content)) { continue; } // <5> 校验是否蕴含 DOCTYPE 若蕴含则为DTD模式 if (hasDoctype(content)) { isDtdValidated = true; break; } // <6> 校验是否是关上的标签， 如果一行有 < 并且前面跟着是字母，那么返回 if (hasOpeningTag(content)) { // End of meaningful data... break; } } // 确定解析形式 return (isDtdValidated ? VALIDATION_DTD : VALIDATION_XSD); } catch (CharConversionException ex) { // Choked on some character encoding... // Leave the decision up to the caller. return VALIDATION_AUTO; } finally { //敞开流 reader.close(); } }- 上述代码中<5>处校验是否蕴含了
DOCTYPE字符，具体代码如下：
/** * The token in a XML document that declares the DTD to use for validation * and thus that DTD validation is being used. */ private static final String DOCTYPE = "DOCTYPE"; /** * 判断是否蕴含 DOCTYPE * Does the content contain the DTD DOCTYPE declaration? */ private boolean hasDoctype(String content) { return content.contains(DOCTYPE); }- <6>处进行了标签的关上判断，代码如下：
/** * Does the supplied content contain an XML opening tag. If the parse state is currently * in an XML comment then this method always returns false. It is expected that all comment * tokens will have consumed for the supplied content before passing the remainder to this method. */ private boolean hasOpeningTag(String content) { if (this.inComment) { return false; } int openTagIndex = content.indexOf('<'); // 获取字符中 < 的索引 return (openTagIndex > -1 // 存在 < && (content.length() > openTagIndex + 1) // 并且前面还有内容 &&Character.isLetter(content.charAt(openTagIndex + 1)));//前面必须是字母 }- 如果抛出异样时
CharConversionException则默认设置为主动VALIDATION_AUTO
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