Displaytag的ExcelView是否可用？导出为纯文本而非有效Excel文件

Great question—Displaytag's Excel export setup can feel counterintuitive at first, so let's unpack this step by step:

What is ExcelView, and why does it output plain text? #

ExcelView is not a final renderer for real XLS files—it's an abstract base class/interface in the core Displaytag library (displaytag-1.2.jar) that defines a common framework for Excel-style exports.

The default implementation in the core library outputs plain, quoted text (like "Agreement Category" "Approving Official" ...) because:

• It’s designed to be lightweight: The core Displaytag jar doesn’t depend on third-party libraries like Apache POI, which are required to generate binary XLS files.
• It provides an "Excel-compatible" text format: This plain text can be easily imported into Excel or other spreadsheet tools, even if it’s not a native binary XLS.

Think of it as a minimal, dependency-free fallback for Excel-like exports, not a full-featured XLS generator.

What is DefaultHssfExportView, and when should you use it? #

org.displaytag.export.excel.DefaultHssfExportView is a concrete implementation that uses Apache POI’s HSSF API to generate valid, binary XLS files. It lives in the separate displaytag-export-poi-1.2.jar because it requires POI dependencies—this keeps the core Displaytag library lean for users who don’t need full Excel export capabilities.

This is the class you should use if you need exports that can be directly opened in Excel without manual import steps.

Key Questions Answered #

1. Is ExcelView a final renderer or an interface/renderer base?
   It’s an abstract base class that defines the structure for Excel exports. It handles common tasks like fetching table data, processing headers, and formatting rows, but leaves the actual "writing to file" logic to subclasses (like DefaultHssfExportView). You can even extend it yourself to create custom Excel export implementations (e.g., using a different spreadsheet library, or outputting a custom text format).

2. Do you need additional implementations?

   • If you’re okay with plain text that can be imported into Excel, no—the default ExcelView implementation works as-is.
   • If you need native XLS files, yes: You’ll need to add the displaytag-export-poi-1.2.jar to your project, and Displaytag will automatically use DefaultHssfExportView for Excel exports (no extra code needed in most cases).

3. Should all Excel exports use DefaultHssfExportView?
   If your goal is to produce standard, native XLS files that work seamlessly with Excel, absolutely. The plain-text ExcelView is only useful if you want to avoid POI dependencies and don’t mind users importing the text file into Excel manually.

Quick Note on Configuration #

Once you add the POI export jar, Displaytag will prioritize DefaultHssfExportView over the plain-text ExcelView when you configure an "excel" export in your JSP or displaytag properties. No extra configuration is usually required—just ensure the jar is in your classpath.

内容的提问来源于stack exchange，提问作者gene b.