一. 案例

1.pom依赖：

<dependency>
    <groupId>com.monitorjbl</groupId>
    <artifactId>xlsx-streamer</artifactId>
    <version>2.1.0</version>
</dependency>

2.读取Excel并转化为csv格式：

// Excel文件地址
public final static String PATH = "xxx";
// 输出的地址
public final static String OUT = "xxx";
// 换行
public final static String NEW_LINE = "
";

public static void test(File file) throws Exception {
          
   
    FileInputStream in = new FileInputStream(file);
    Workbook wk = StreamingReader.builder()
            .rowCacheSize(100)
            .bufferSize(4096)
            .open(in);
    int sheetNums = wk.getNumberOfSheets();
    int count = 0;
    StringBuilder fileBuilder = new StringBuilder();

    for (int i = 0; i < sheetNums; i++) {
          
   
        StreamingSheet sheet = (StreamingSheet) wk.getSheetAt(i);
        // 遍历所有的行
        for (Row row : sheet) {
          
   
            // 遍历所有的列
            int size = ((StreamingRow) row).getCellMap().size();
            for (int col = 0; col < size; col++) {
          
   
                StreamingCell cell = (StreamingCell) row.getCell(col);
                String tmp = (col == size - 1) ? "" : ",";
                fileBuilder.append(cell.getStringCellValue() + tmp);
            }
            // 换行
            fileBuilder.append(NEW_LINE);
            count++;
        }
    }
    System.out.println("Count: " + count);
    String res = fileBuilder.toString();
    try {
          
   
        Files.write(Paths.get(OUT), res.getBytes(StandardCharsets.UTF_8));
    } finally {
          
   
        in.close();
    }
}

3.测试，准备一个excel表格： 4.修改下文件地址和输出，运行程序后，结果如下： csv格式的文件：