To mimic JSF's default error handling and validation you would have to configure Struts to use the validator framework or implement the equivalent in the validate method on an ActionForm.
要模仿 JSF 默认错误处理和验证，还必须配置 Struts 使用验证器框架，或者在 ActionForm上的 validate方法中实现等价的操作。
The Struts framework calls validate automatically, and if any item fails validation, the form page is rendered again.
Struct框架自动的调用validate，并在验证失败时重新渲染表单页面。
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