在爪哇/jSTL中格式化文件大小[复制]

一个快速的谷歌搜索返回了我 this 来自AppacheHadoop项目。从那里复制: (Apache许可证,2.0版):

private static DecimalFormat oneDecimal = new DecimalFormat("0.0");

  /**
   * Given an integer, return a string that is in an approximate, but human 
   * readable format. 
   * It uses the bases 'k', 'm', and 'g' for 1024, 1024**2, and 1024**3.
   * @param number the number to format
   * @return a human readable form of the integer
   */
  public static String humanReadableInt(long number) {
    long absNumber = Math.abs(number);
    double result = number;
    String suffix = "";
    if (absNumber < 1024) {
      // nothing
    } else if (absNumber < 1024 * 1024) {
      result = number / 1024.0;
      suffix = "k";
    } else if (absNumber < 1024 * 1024 * 1024) {
      result = number / (1024.0 * 1024);
      suffix = "m";
    } else {
      result = number / (1024.0 * 1024 * 1024);
      suffix = "g";
    }
    return oneDecimal.format(result) + suffix;
  }

它使用1K=1024,但如果您愿意,您可以对此进行调整。您还需要使用不同的decimalFormat处理<1024大小写。

你可以使用通用IO FileUtils.byteCountToDisplaySize 方法。对于JSTL实现,可以在类路径上具有commons io的同时添加以下taglib函数:

<function>
  <name>fileSize</name>
  <function-class>org.apache.commons.io.FileUtils</function-class>
  <function-signature>String byteCountToDisplaySize(long)</function-signature>
</function>

现在,在JSP中,您可以执行以下操作:

<%@ taglib uri="/WEB-INF/FileSizeFormatter.tld" prefix="sz"%>
Some Size: ${sz:fileSize(1024)} <!-- 1 K -->
Some Size: ${sz:fileSize(10485760)} <!-- 10 MB -->