Validator类负责控制运行时内容树的验证。

三种形式的验证

Unmarshal-Time Validation

This form of validation enables a client application to receive information about validation errors and warnings detected while unmarshalling XML data into a Java content tree and is completely orthogonal to the other types of validation. To enable or disable it, see the javadoc for Unmarshaller.setValidating. All JAXB 1.0 Providers are required to support this operation.

On-Demand Validation

This form of validation enables a client application to receive information about validation errors and warnings detected in the Java content tree. At any point, client applications can call the Validator.validate method on the Java content tree (or any sub-tree of it). All JAXB 1.0 Providers are required to support this operation.

Fail-Fast Validation

This form of validation enables a client application to receive immediate feedback about modifications to the Java content tree that violate type constraints on Java Properties as defined in the specification. JAXB Providers are not required support this type of validation. Of the JAXB Providers that do support this type of validation, some may require you to decide at schema compile time whether or not a client application will be allowed to request fail-fast validation at runtime.

Validator课程负责管理按需验证。 Unmarshaller课程负责在解散操作期间管理Unmarshal-Time Validation。 虽然在组织操作中没有正式的启用验证的方法，但是Marshaller可能会检测到错误，这些错误将被报告到其上注册的 ValidationEventHandler。

使用默认EventHandler

If the client application does not set an event handler on their Validator, Unmarshaller, or Marshaller prior to calling the validate, unmarshal, or marshal methods, then a default event handler will receive notification of any errors or warnings encountered. The default event handler will cause the current operation to halt after encountering the first error or fatal error (but will attempt to continue after receiving warnings).

处理验证事件

There are three ways to handle events encountered during the unmarshal, validate, and marshal operations:

Use the default event handler

The default event handler will be used if you do not specify one via the setEventHandler API's on Validator, Unmarshaller, or Marshaller.

Implement and register a custom event handler

Client applications that require sophisticated event processing can implement the ValidationEventHandler interface and register it with the Unmarshaller and/or Validator.

Use the ValidationEventCollector utility

For convenience, a specialized event handler is provided that simply collects any ValidationEvent objects created during the unmarshal, validate, and marshal operations and returns them to the client application as a java.util.Collection.

验证和成型

Validation events are handled differently depending on how the client application is configured to process them as described in the previous section. However, there are certain cases where a JAXB Provider indicates that it is no longer able to reliably detect and report errors. In these cases, the JAXB Provider will set the severity of the ValidationEvent to FATAL_ERROR to indicate that the unmarshal, validate, or marshal operations should be terminated. The default event handler and ValidationEventCollector utility class must terminate processing after being notified of a fatal error. Client applications that supply their own ValidationEventHandler should also terminate processing after being notified of a fatal error. If not, unexpected behaviour may occur.

支持的属性

There currently are not any properties required to be supported by all JAXB Providers on Validator. However, some providers may support their own set of provider specific properties.