UpdateSensitiveClobLocatorReader (Apache Derby V10.14 Internals)

java.lang.Object
- java.io.Reader
- - org.apache.derby.client.am.UpdateSensitiveClobLocatorReader

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.lang.Readable
```
class UpdateSensitiveClobLocatorReader
extends java.io.Reader
```
Wraps a Buffered Clob locator reader and watches out for updates on the Clob associated with it. Before a read operation is performed on the Reader this stream verifies that the underlying Clob has not changed and if it has it recreates the specific streams.

Field Summary

Fields
Modifier and Type	Field	Description
`private ClientClob`	`clob`
`private ClientConnection`	`con`
`private long`	`currentPos`
`private long`	`length`
`private java.io.BufferedReader`	`r`
`private long`	`updateCount`

Fields inherited from class java.io.Reader
lock

Constructor Summary

Constructors
Modifier	Constructor	Description
`protected`	`UpdateSensitiveClobLocatorReader(ClientConnection con, ClientClob clob)`	Initializes the Reader, updateCount, currentPos and the connection to the appropriate values.
`protected`	`UpdateSensitiveClobLocatorReader(ClientConnection con, ClientClob clob, long pos, long len)`	Initializes the Reader, updateCount, currentPos, length and the connection to the appropriate values.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`close()`
`private void`	`identifyAndReplaceObseleteStream()`	Verifies whether the current updateCount matches the updateCount of the Clob object and if it does not it recreates the stream.
`int`	`read()`
`int`	`read(char[] c, int off, int len)`
`private java.io.Reader`	`reCreateStream()`	Re-creates the underlying Locator stream with the current position and the length values if specified.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from class java.io.Reader
mark, markSupported, read, read, ready, reset, skip, transferTo

- Field Detail
  - r
```
private java.io.BufferedReader r
```
  - con
```
private ClientConnection con
```
  - clob
```
private ClientClob clob
```
  - updateCount
```
private long updateCount
```
  - currentPos
```
private long currentPos
```
  - length
```
private long length
```
- Constructor Detail
  - UpdateSensitiveClobLocatorReader
```
protected UpdateSensitiveClobLocatorReader(ClientConnection con,
                                           ClientClob clob)
                                    throws SqlException
```
    Initializes the Reader, updateCount, currentPos and the connection to the appropriate values.
    
    Parameters:
    
    con - connection to be used to read the Clob value from the server
    
    clob - the Clob object associated with this stream.
    
    Throws:
    
    SqlException
  - UpdateSensitiveClobLocatorReader
```
protected UpdateSensitiveClobLocatorReader(ClientConnection con,
                                           ClientClob clob,
                                           long pos,
                                           long len)
                                    throws SqlException
```
    Initializes the Reader, updateCount, currentPos, length and the connection to the appropriate values.
    
    Parameters:
    
    con - connection to be used to read the Clob value from the server
    
    clob - the Clob object associated with this reader.
    
    pos - the position from which the first read begins.
    
    len - the length in bytes of the partial value to be retrieved.
    
    Throws:
    
    SqlException
- Method Detail
  - read
```
public int read()
         throws java.io.IOException
```
    Overrides:
    
    read in class java.io.Reader
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    Reader.read()
  - read
```
public int read(char[] c,
                int off,
                int len)
         throws java.io.IOException
```
    Specified by:
    
    read in class java.io.Reader
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    Reader.read(char[], int, int)
  - close
```
public void close()
           throws java.io.IOException
```
    Specified by:
    
    close in interface java.lang.AutoCloseable
    
    Specified by:
    
    close in interface java.io.Closeable
    
    Specified by:
    
    close in class java.io.Reader
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    Reader.close()
  - identifyAndReplaceObseleteStream
```
private void identifyAndReplaceObseleteStream()
                                       throws java.io.IOException
```
    Verifies whether the current updateCount matches the updateCount of the Clob object and if it does not it recreates the stream.
    
    Throws:
    
    java.io.IOException - If any exception occurs upon Locator stream creation.
  - reCreateStream
```
private java.io.Reader reCreateStream()
                               throws SqlException
```
    Re-creates the underlying Locator stream with the current position and the length values if specified.
    
    Throws:
    
    SqlException

Class UpdateSensitiveClobLocatorReader

Field Summary

Fields inherited from class java.io.Reader

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from class java.io.Reader

Field Detail

r

con

clob

updateCount

currentPos

length

Constructor Detail

UpdateSensitiveClobLocatorReader

UpdateSensitiveClobLocatorReader

Method Detail

read

read

close

identifyAndReplaceObseleteStream

reCreateStream