如何使用Apache PDFBox提取PDPushButton的标签文本？

Got it, let's work through this problem. When you've converted a PDTerminalField to a PDPushButton but can't find a direct method to pull its label, here are practical approaches to try—these are tailored to common PDF SDK workflows (like Adobe's Acrobat SDK):

• Check the Widget Annotation's Appearance Dictionary (AP)
  Most PDF buttons store their visual label in the appearance dictionary of their associated widget annotation. Here's a rough workflow:

  1. Use PDPushButtonGetWidget(yourPushButton) to retrieve the widget annotation linked to the button.
  2. Call PDAnnotGetAP(widgetAnnot) to get the AP dictionary.
  3. Access the "Normal" state entry (usually /N) from the AP dictionary, which holds the appearance stream or Form XObject for the button's default look.
  4. Parse this appearance content to extract text—look for text operators like Tj or TJ which render string content.

• Inspect Field Dictionary Fields: TU or T
  Sometimes button labels are stored in unexpected places:

  • The TU key (ToolTip) might contain the button's visible label (even though it's intended for tooltips, some PDF generators repurpose it).
  • The T key is the field name, but if the button's label matches its field name, this could work.
    Use PDFieldGetDict((PDField)yourPushButton) to get the field's dictionary, then ASDictGetString to fetch values for these keys.

• Try PDFieldGetValueAsString
  Even though buttons are typically interactive fields, some PDFs store the button label as the field's value. Give this a shot:

  ASString label = PDFieldGetValueAsString((PDField)yourPushButton);
  

• Debug the Dictionary Structure
  If none of the above work, print out all key-value pairs in the button's field dictionary and widget annotation dictionary. This can reveal custom or non-standard keys where the label might be hidden—different PDF generators often have unique ways of storing this data.

内容的提问来源于stack exchange，提问作者sas1138