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db4o 2.0 | ||||||||
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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
the db4o Blob type to store blobs independant of the main database
file and 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 seperate
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.
Field Summary | |
static double |
STATUS_AVAILABLE
available data was previously stored to the Blob field. |
static double |
STATUS_COMPLETED
the last operation on this field was completed successfully |
static double |
STATUS_ERROR
the last operation on this field failed |
static double |
STATUS_QUEUED
an operation was triggered and is waiting for it's turn in the Blob queue. |
static double |
STATUS_UNUSED
no data was ever stored to the Blob field. |
Method Summary | |
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 |
writeTo(java.io.File file)
writes stored blob data to a file. |
Field Detail |
public static final double STATUS_UNUSED
public static final double STATUS_AVAILABLE
public static final double STATUS_QUEUED
public static final double STATUS_COMPLETED
public static final double STATUS_ERROR
Method Detail |
public double getStatus()
public void 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 storedpublic 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 errors
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db4o 2.0 | ||||||||
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