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public interface Blob
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.
Method Summary | |
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void |
deleteFile()
Deletes the current file stored in this BLOB. |
java.lang.String |
getFileName()
returns the name of the file the blob was stored to. |
double |
getStatus()
returns the status after the last read- or write-operation. |
void |
readFrom(java.io.File file)
reads a file into the db4o system and stores it as a blob. |
void |
readLocal(java.io.File file)
reads a file into the db4o system and stores it as a blob. |
void |
writeLocal(java.io.File file)
writes stored blob data to a file. |
void |
writeTo(java.io.File file)
writes stored blob data to a file. |
Method Detail |
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java.lang.String getFileName()
double getStatus()
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.Status
constants defined in this interface or a double
between 0 and 1 that signifies the completion of the currently running operation.
constants
void readFrom(java.io.File file) throws java.io.IOException
file
- the file the blob is to be read from.
java.io.IOException
- in case of errorsvoid readLocal(java.io.File file) throws java.io.IOException
file
- the file the blob is to be read from.
java.io.IOException
- in case of errorsvoid writeLocal(java.io.File file) throws java.io.IOException
file
- the file the blob is to be written to.
java.io.IOException
- in case of errors and in case no blob
data was storedvoid writeTo(java.io.File file) throws java.io.IOException
file
- the file the blob is to be written to.
java.io.IOException
- in case of errors and in case no blob
data was storedvoid deleteFile() throws java.io.IOException
java.io.IOException
- in case of errors and in case no
data was stored
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