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ExcelReader pattern

The ExcelReader pattern is a design approach for processing Excel files that utilizes a listener mechanism to handle data row by row.^[600-developer__java__3-party__easyExcel.md] This pattern is implemented within libraries like Alibaba EasyExcel to optimize memory usage and read performance.

Mechanism

The core of the pattern involves registering an AnalysisEventListener with an ExcelReader instance.^[600-developer__java__3-party__easyExcel.md] Instead of loading the entire file into memory at once, the reader iterates through the file and triggers the listener's invoke method for each row of data.^[600-developer__java__3-party__easyExcel.md]

Implementation

The listener interface requires overriding specific methods to handle the data stream:

  • invoke(List<String> object, AnalysisContext context): This method is called for every row read, allowing for custom processing or storage of the data.^[600-developer__java__3-party__easyExcel.md]
  • doAfterAllAnalysed(AnalysisContext context): This method is invoked once all data has been read, often used for cleanup or final aggregation steps.^[600-developer__java__3-party__easyExcel.md]

Sources

^[600-developer__java__3-party__easyExcel.md]