ClobLocatorReader (Apache Derby V10.14 Internals)

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

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.lang.Readable
```
class ClobLocatorReader
extends java.io.Reader
```
An Reader that will use an locator to fetch the Clob value from the server.
This Reader implementation is pretty basic. No buffering of data is done. Hence, for efficiency #read(char[]) should be used instead of #read(). Marks are not supported, but it should be pretty simple to extend the implementation to support this. A more efficient skip implementation should also be straight-forward.

Field Summary

Fields
Modifier and Type	Field	Description
`private ClientClob`	`clob`	The Clob to be accessed.
`private ClientConnection`	`connection`	Connection used to read Clob from server.
`private long`	`currentPos`	Current position in the underlying Clob.
`private boolean`	`isClosed`	Stores the information to whether this Reader has been closed or not.
`private long`	`maxPos`	Position in Clob where to stop reading.

Fields inherited from class java.io.Reader
lock

Constructor Summary

Constructors
Constructor	Description
`ClobLocatorReader(ClientConnection connection, ClientClob clob)`	Create an `Reader` for reading the `Clob` value represented by the given locator based `Clob` object.
`ClobLocatorReader(ClientConnection connection, ClientClob clob, long pos, long len)`	Create an `Reader` for reading the `Clob` value represented by the given locator based `Clob` object.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private void`	`checkClosed()`	Check to see if this `Reader` is closed.
`void`	`close()`
`int`	`read()`
`int`	`read(char[] c, int off, int len)`
`private char[]`	`readCharacters(int len)`	Read the next `len` characters of the `Clob` value from the server.

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
  - connection
```
private final ClientConnection connection
```
    Connection used to read Clob from server.
  - clob
```
private final ClientClob clob
```
    The Clob to be accessed.
  - currentPos
```
private long currentPos
```
    Current position in the underlying Clob. Clobs are indexed from 1
  - maxPos
```
private final long maxPos
```
    Position in Clob where to stop reading. maxPos starts counting from 1.
  - isClosed
```
private boolean isClosed
```
    Stores the information to whether this Reader has been closed or not. Is set to true if close() has been called. Is false otherwise.
- Constructor Detail
  - ClobLocatorReader
```
ClobLocatorReader(ClientConnection connection,
                  ClientClob clob)
           throws SqlException
```
    Create an Reader for reading the Clob value represented by the given locator based Clob object.
    
    Parameters:
    
    connection - connection to be used to read the Clob value from the server
    
    clob - Clob object that contains locator for the Clob value on the server.
    
    Throws:
    
    SqlException
  - ClobLocatorReader
```
ClobLocatorReader(ClientConnection connection,
                  ClientClob clob,
                  long pos,
                  long len)
           throws SqlException
```
    Create an Reader for reading the Clob value represented by the given locator based Clob object.
    
    Parameters:
    
    connection - connection to be used to read the Clob value from the server
    
    clob - Clob object that contains locator for the Clob value on the server.
    
    pos - The offset to the first character of the partial value to be retrieved.
    
    len - The length in characters 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:
    
    This method fetches one character at a time from the server. For more efficient retrieval, use #read(char[]).
  - 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()
  - checkClosed
```
private void checkClosed()
                  throws java.io.IOException
```
    Check to see if this Reader is closed. If it is closed throw an IOException that states that the stream is closed.
    
    Throws:
    
    java.io.IOException - if isClosed = true.
  - readCharacters
```
private char[] readCharacters(int len)
                       throws java.io.IOException
```
    Read the next len characters of the Clob value from the server.
    
    Parameters:
    
    len - number of characters to read.
    
    Returns:
    
    char[] containing the read characters.
    
    Throws:
    
    java.io.IOException - Wrapped SqlException if reading from server fails.

Class ClobLocatorReader

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

connection

clob

currentPos

maxPos

isClosed

Constructor Detail

ClobLocatorReader

ClobLocatorReader

Method Detail

read

read

close

checkClosed

readCharacters