ChecksumPolicy (Maven Artifact Resolver SPI 1.0.3 API)

public interface ChecksumPolicy

A checksum policy gets employed by repository connectors to validate the integrity of a downloaded file. For each downloaded file, a checksum policy instance is obtained and presented with the available checksums to conclude whether the download is valid or not. The following pseudo-code illustrates the usage of a checksum policy by a repository connector in some more detail (the retry logic has been omitted for the sake of brevity):

 void validateChecksums() throws ChecksumFailureException {
   for (checksum : checksums) {
     switch (checksum.state) {
       case MATCH:
         if (policy.onChecksumMatch(...)) {
           return;
         }
         break;
       case MISMATCH:
         policy.onChecksumMismatch(...);
         break;
       case ERROR:
         policy.onChecksumError(...);
         break;
     }
   }
   policy.onNoMoreChecksums();
 }
 
 void downloadFile() throws Exception {
   ...
   policy = newChecksumPolicy();
   try {
     validateChecksums();
   } catch (ChecksumFailureException e) {
     if (!policy.onTransferChecksumFailure(...)) {
       throw e;
     }
   }
 }

Checksum policies might be stateful and are generally not thread-safe.

Field Summary

Fields
Modifier and Type Field and Description

static int KIND_UNOFFICIAL
Bit flag indicating a checksum which is not part of the official repository layout/structure.

Fields
Modifier and Type	Field and Description
`static int`	`KIND_UNOFFICIAL` Bit flag indicating a checksum which is not part of the official repository layout/structure.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`onChecksumError(String algorithm, int kind, org.eclipse.aether.transfer.ChecksumFailureException exception)` Signals an error while computing the local checksum value or retrieving the checksum value from the remote repository.
`boolean`	`onChecksumMatch(String algorithm, int kind)` Signals a match between the locally computed checksum value and the checksum value declared by the remote repository.
`void`	`onChecksumMismatch(String algorithm, int kind, org.eclipse.aether.transfer.ChecksumFailureException exception)` Signals a mismatch between the locally computed checksum value and the checksum value declared by the remote repository.
`void`	`onNoMoreChecksums()` Signals that all available checksums have been processed.
`boolean`	`onTransferChecksumFailure(org.eclipse.aether.transfer.ChecksumFailureException exception)` Signals that (even after a potential retry) checksum validation has failed.
`void`	`onTransferRetry()` Signals that the download is being retried after a previously thrown `ChecksumFailureException` that is `retry-worthy`.

- Field Detail
  - KIND_UNOFFICIAL
```
static final int KIND_UNOFFICIAL
```
    Bit flag indicating a checksum which is not part of the official repository layout/structure.
    
    See Also:
    Constant Field Values
- Method Detail
  - onChecksumMatch
```
boolean onChecksumMatch(String algorithm,
                      int kind)
```
    Signals a match between the locally computed checksum value and the checksum value declared by the remote repository.
    
    Parameters:
    algorithm - The name of the checksum algorithm being used, must not be null.
    kind - A bit field providing further details about the checksum. See the KIND_* constants in this interface for possible bit flags.
    
    Returns:
    true to accept the download as valid and stop further validation, false to continue validation with the next checksum.
  - onChecksumMismatch
```
void onChecksumMismatch(String algorithm,
                      int kind,
                      org.eclipse.aether.transfer.ChecksumFailureException exception)
                        throws org.eclipse.aether.transfer.ChecksumFailureException
```
    Signals a mismatch between the locally computed checksum value and the checksum value declared by the remote repository. A simple policy would just rethrow the provided exception. More sophisticated policies could update their internal state and defer a conclusion until all available checksums have been processed.
    
    Parameters:
    algorithm - The name of the checksum algorithm being used, must not be null.
    kind - A bit field providing further details about the checksum. See the KIND_* constants in this interface for possible bit flags.
    exception - The exception describing the checksum mismatch, must not be null.
    
    Throws:
    
    org.eclipse.aether.transfer.ChecksumFailureException - If the checksum validation is to be failed. If the method returns normally, validation continues with the next checksum.
  - onChecksumError
```
void onChecksumError(String algorithm,
                   int kind,
                   org.eclipse.aether.transfer.ChecksumFailureException exception)
                     throws org.eclipse.aether.transfer.ChecksumFailureException
```
    Signals an error while computing the local checksum value or retrieving the checksum value from the remote repository.
    
    Parameters:
    algorithm - The name of the checksum algorithm being used, must not be null.
    kind - A bit field providing further details about the checksum. See the KIND_* constants in this interface for possible bit flags.
    exception - The exception describing the checksum error, must not be null.
    
    Throws:
    
    org.eclipse.aether.transfer.ChecksumFailureException - If the checksum validation is to be failed. If the method returns normally, validation continues with the next checksum.
  - onNoMoreChecksums
```
void onNoMoreChecksums()
                       throws org.eclipse.aether.transfer.ChecksumFailureException
```
    Signals that all available checksums have been processed.
    
    Throws:
    
    org.eclipse.aether.transfer.ChecksumFailureException - If the checksum validation is to be failed. If the method returns normally, the download is assumed to be valid.
  - onTransferRetry
```
void onTransferRetry()
```
    Signals that the download is being retried after a previously thrown ChecksumFailureException that is retry-worthy. Policies that maintain internal state will usually have to reset some of this state at this point to prepare for a new round of validation.
  - onTransferChecksumFailure
```
boolean onTransferChecksumFailure(org.eclipse.aether.transfer.ChecksumFailureException exception)
```
    Signals that (even after a potential retry) checksum validation has failed. A policy could opt to merely log this issue or insist on rejecting the downloaded file as unusable.
    
    Parameters:
    exception - The exception that was thrown from a prior call to onChecksumMismatch(String, int, ChecksumFailureException), onChecksumError(String, int, ChecksumFailureException) or onNoMoreChecksums().
    
    Returns:
    true to accept the download nevertheless and let artifact resolution succeed, false to reject the transferred file as unusable.

Interface ChecksumPolicy

Field Summary

Method Summary

Field Detail

KIND_UNOFFICIAL

Method Detail

onChecksumMatch

onChecksumMismatch

onChecksumError

onNoMoreChecksums

onTransferRetry

onTransferChecksumFailure