Calculate MD5 digest of a resource in the bundle

Summary

The md5 macro calculates the MD5 hash of a resource that exists within the current bundle JAR. The result can be returned as either Base64 (default) or hexadecimal encoding.

Syntax 

${md5;<resource-path>[;<encoding>]}

Parameters

  • resource-path - Path to a resource within the bundle (e.g., “META-INF/MANIFEST.MF”)
  • encoding (optional) - Output encoding: “hex” for hexadecimal, “base64” for Base64 (default)

Behavior

  • Locates the resource within the bundle being built
  • Calculates the MD5 digest of the resource contents
  • Returns the digest in the specified encoding (Base64 by default)
  • Throws an exception if the resource is not found

Examples

Get MD5 of a resource (Base64):

${md5;META-INF/services/com.example.Service}
# Returns Base64-encoded MD5

Get MD5 in hexadecimal format:

${md5;config/application.properties;hex}
# Returns: "5d41402abc4b2a76b9719d911017c592" (example)

Hash manifest file:

manifest.md5=${md5;META-INF/MANIFEST.MF;hex}

Verify resource integrity:

Bundle-ResourceMD5: ${md5;important-config.xml}

Use Cases

  • Verifying resource integrity in bundles
  • Generating resource checksums for validation
  • Creating content-based identifiers
  • Implementing resource version checking
  • Integrity verification in manifests
  • Detecting resource tampering

Notes

  • Resource path is relative to the bundle root
  • Only works with resources that are part of the bundle being built
  • MD5 is considered cryptographically weak; use for checksums only, not security
  • Default encoding is Base64
  • Hex encoding produces lowercase hexadecimal strings
  • Throws FileNotFoundException if resource doesn’t exist
  • See also: ${sha1} and ${digest} for other hash algorithms

See test cases in MacroTestsForDocsExamples.java