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| com.db4o.types.Blob
All known Subclasses: com.db4o.internal.BlobImpl,
| Blob | | public interface Blob extends Db4oType(Code) | | the db4o Blob type to store blobs independent of the main database
file and allows to perform asynchronous upload and download operations.
Usage:
- Define Blob fields on your user classes.
- As soon as an object of your class is stored, db4o automatically
takes care that the Blob field is set.
- Call readFrom to read a blob file into the db4o system.
- Call writeTo to write a blob file from within the db4o system.
- getStatus may help you to determine, whether data has been
previously stored. It may also help you to track the completion
of the current process.
db4o client/server carries out all blob operations in a separate
thread on a specially dedicated socket. One socket is used for
all blob operations and operations are queued. Your application
may continue to access db4o while a blob is transferred in the
background.
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| Method Summary | |
| public void | deleteFile()
Deletes the current file stored in this BLOB. | | public String | getFileName()
returns the name of the file the blob was stored to. | | public double | getStatus()
returns the status after the last read- or write-operation. | | public void | readFrom(File file)
reads a file into the db4o system and stores it as a blob. | | public void | readLocal(File file)
reads a file into the db4o system and stores it as a blob.
db4o will use the local file system in Client/Server mode also. | | public void | writeLocal(File file)
writes stored blob data to a file.
db4o will use the local file system in Client/Server mode also. | | public void | writeTo(File file)
writes stored blob data to a file. |
| deleteFile | | public void deleteFile() throws IOException(Code) | | Deletes the current file stored in this BLOB.
throws:
IOException - in case of errors and in case nodata was stored |
| getFileName | | public String getFileName()(Code) | | returns the name of the file the blob was stored to.
The method may return null, if the file was never
stored.
String the name of the file. |
| getStatus | | public double getStatus()(Code) | | returns the status after the last read- or write-operation.
The status value returned may be any of the following:
Status.UNUSED no data was ever stored to the Blob field.
Status.AVAILABLE available data was previously stored to the Blob field.
Status.QUEUED an operation was triggered and is waiting for it's turn in the Blob queue.
Status.COMPLETED the last operation on this field was completed successfully.
Status.PROCESSING for internal use only.
Status.ERROR the last operation failed.
or a double between 0 and 1 that signifies the current completion percentage of the currently
running operation.
the five STATUS constants defined in this interface or a double
between 0 and 1 that signifies the completion of the currently running operation.
status - the current status
See Also: com.db4o.ext.Status
See Also: STATUS constants |
| readFrom | | public void readFrom(File file) throws IOException(Code) | | reads a file into the db4o system and stores it as a blob.
In Client/Server mode db4o will open an additional socket and
process writing data in an additional thread.
Parameters:
file - the file the blob is to be read from.
throws:
IOException - in case of errors |
| readLocal | | public void readLocal(File file) throws IOException(Code) | | reads a file into the db4o system and stores it as a blob.
db4o will use the local file system in Client/Server mode also.
Parameters:
file - the file the blob is to be read from.
throws:
IOException - in case of errors |
| writeLocal | | public void writeLocal(File file) throws IOException(Code) | | writes stored blob data to a file.
db4o will use the local file system in Client/Server mode also.
throws:
IOException - in case of errors and in case no blobdata was stored
Parameters:
file - the file the blob is to be written to. |
| writeTo | | public void writeTo(File file) throws IOException(Code) | | writes stored blob data to a file.
In Client/Server mode db4o will open an additional socket and
process writing data in an additional thread.
throws:
IOException - in case of errors and in case no blobdata was stored
Parameters:
file - the file the blob is to be written to. |
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