com.ibm.websphere.logging.hpel
Class LogRecordContext
- java.lang.Object
com.ibm.websphere.logging.hpel.LogRecordContext
- public class LogRecordContext
- extends java.lang.Object
Code that needs to add key-value pairs to log and trace records can register a key, and a corresponding LogRecordContext.Extension callback via the registerExtension method.
Log handlers can then use these key-value pairs in log and trace output by calling the getExtensions method, which in turn calls back to any registered LogRecordContext.Extension callbacks to populate the key-value pairs into a Map.
As an example, the following code could be used to add a LogRecordContext.Extension that provides the ThreadId of the current thread.
import com.ibm.websphere.logging.hpel.LogRecordContext; public class ThreadIdExtension { // a strong reference to the LogRecordContext.Extension to make // sure it is not garbage collected private final static LogRecordContext.Extension extension = new LogRecordContext.Extension() { public String getValue() { return Long.toString(Thread.currentThread().getId()); } }; public static void init() { LogRecordContext.registerExtension("ThreadId", extension); } public static void destroy() { LogRecordContext.unregisterExtension("ThreadId"); } }A log handler could then make use of this information as follows:
import java.io.PrintWriter; import java.util.HashMap; import java.util.Map; import java.util.logging.Handler; import java.util.logging.LogRecord; import com.ibm.websphere.logging.hpel.LogRecordContext; public class MyHandler extends Handler { private PrintWriter printWriter; MyHandler(PrintWriter printWriter) { this.printWriter = printWriter; } public void close() { printWriter.close(); } public void flush() { printWriter.flush(); } public void publish(LogRecord record) { MapNote that the HPEL handlers callcontext = new HashMap (); // get the extension keys/values LogRecordContext.getExtensions(context); String threadId = context.get("ThreadId"); printWriter.println("[" + threadId + "] " + record.getMessage()); } }
LogRecordContext.getExtensions
and store the resultant key-value pairs in the log and trace data
repositories. This information can then be accessed via the
com.ibm.websphere.logging.hpel.reader.RepositoryLogRecord getExtensions
method. Extension information can also be used for filtering log and trace
records via the LogViewer command line tool's -includeExtensions option.
Nested Class Summary
Modifier and Type | Class and Description |
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|
LogRecordContext.Extension
Call back interface to retrieve current extension value.
|
Constructor Summary
Constructor and Description |
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LogRecordContext()
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Method Summary
Modifier and Type | Method and Description |
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getExtensions(java.util.Map<java.lang.String,java.lang.String> map)
Retrieves values for all registered context extensions.
|
|
registerExtension(java.lang.String key,LogRecordContext.Extension extension)
Registers new context extension.
|
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unregisterExtension(java.lang.String key)
Removes context extension registration.
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Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail
LogRecordContext
- public LogRecordContext()
Method Detail
registerExtension
- public static void registerExtension( java.lang.String key,
- LogRecordContext.Extension extension)
Registers new context extension.
To avoid memory leaks Extensions are stored as weak references. It means that caller need to keep strong
reference (a static field for example) to keep that extension in the registration map.
Parameters:
key
- String key to associate with the registered extension extension
- LogRecordContext.Extension
implementation returning extension runtime values Throws:
java.lang.IllegalArgumentException
- if parameter key
or extension
are null
; or if key
already has extension associated with it. unregisterExtension
- public static boolean unregisterExtension( java.lang.String key)
Removes context extension registration.
Parameters:
key
- String key associated with the registered extension. Returns:
true
if key had extension associated with it. Throws:
java.lang.IllegalArgumentException
- if parameter key
is null
. getExtensions
- public static void getExtensions( java.util.Map<java.lang.String,java.lang.String> map)
- throws java.lang.IllegalArgumentException
Retrieves values for all registered context extensions.
Parameters:
map
- Map
instance to populate with key-value pairs of
the context extensions. Throws:
java.lang.IllegalArgumentException
- if parameter map
is null