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Code Issues Projects Releases Wiki Activity

Configuration Admin Service: Added nullness annotations in examples (#1105) 

* Added nullness annotations

- Added nullness annotations
- Applied formatter
- Fixed example code

Signed-off-by: Christoph Weitkamp <github@christophweitkamp.de>

* Improved Hint

Signed-off-by: Jerome Luckenbach <github@luckenba.ch>
pull/1111/head
Christoph Weitkamp 2019-12-18 22:28:27 +01:00 committed by Jerome Luckenbach
parent 31537a2f04
commit e82b539c6f
1 changed files with 48 additions and 26 deletions
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74
developers/osgi/configadmin.md
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@ -52,16 +52,21 @@ import java.util.Date;
import java.util.Map;
import org.osgi.service.component.ComponentContext;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Deactivate;
import org.osgi.service.component.annotations.Modified;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventHandler;
@Component(service={TimeEventHandler.class, EventHandler.class}, property={"event.topics=some/topic"})
@Component(service = { TimeEventHandler.class, EventHandler.class }, property = { "event.topics=some/topic" })
@NonNullByDefault
public class TimeEventHandler implements EventHandler {
// Use the default formatter
private SimpleDateFormat dateFormatter = new SimpleDateFormat();
@Activated
@Activate
protected void activate(ComponentContext context, Map<String, Object> properties) {
modified(properties);
}
@ -78,13 +83,13 @@ public class TimeEventHandler implements EventHandler {
}
}
@Deactivated
@Deactivate
protected void deactivate(ComponentContext context, Map<String, Object> properties) {
modified(properties);
}
@Override
public void handleEvent(Event event) {
public void handleEvent(@Nullable Event event) {
Long timeInMillis = (Long) event.getProperty("time");
Date date = new Date(timeInMillis);
System.out.println("The current time is: " + dateFormatter.format(date));
@ -99,40 +104,57 @@ It can be used to update the configuration (or create if it is missing) as well.
The flow is the following:
```java
@Component(service={TimeEventHandler.class})
public class TimeEventHandler{
package com.example;
import java.io.IOException;
import java.util.Dictionary;
import java.util.Hashtable;
import org.eclipse.jdt.annotation.NonNullByDefault;
import org.osgi.service.cm.Configuration;
import org.osgi.service.cm.ConfigurationAdmin;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
@Component(service = TimeEventHandler.class)
@NonNullByDefault
public class TimeEventHandler {
@Reference
ConfigurationAdmin configurationAdmin;
private @NonNullByDefault({}) ConfigurationAdmin configurationAdmin;
// Here we perform a configuration update as soon as this service gets activated
@Activated
@Activate
protected void activate() {
Configuration config = configurationAdmin.getConfiguration("com.example.handler", null);
Dictionary<String, Object> props = config.getProperties();
try {
Configuration config = configurationAdmin.getConfiguration("com.example.handler", null);
Dictionary<String, Object> props = config.getProperties();
if (props == null) { // if null, the configuration is new
props = new Hashtable();
if (props == null) { // if null, the configuration is new
props = new Hashtable<>();
}
// set some properties
props.put("formatting", "EEE, d MMM yyyy HH:mm:ss Z");
// update the configuration, the target bundle will be notified for the change
config.update(props);
} catch (IOException e) {
// TODO: handle exception
}
// set some properties
props.put("formatting", "EEE, d MMM yyyy HH:mm:ss Z");
// update the configuration, the target bundle will be notified for the change
config.update(props);
}
}
```
After the call to `update` the Configuration Admin service persists the new configuration data and sends an update to the ManagedService registered with the service PID asynchronously.
Hint!
Configuration objects have a security feature called `Location` that prevents other
bundles from modifying their configuration. In the example above we have created a
configuration using the `Configuration config = configurationAdmin.getConfiguration
("com.example.handler", null);`. The second parameter ('null') guarantees that the
location for the configuration will be set when the service with this PID is
registered for the first time. If the location is not set correctly the Config
Admin may not send the update to the bundle.
::: tip Hint!
Configuration objects have a security feature called `Location` that prevents other bundles from modifying their configuration.
In the example above we have created a configuration using the `Configuration config = configurationAdmin.getConfiguration("com.example.handler", null);`.
The second parameter ('null') guarantees that the location for the configuration will be set when the service with this PID is registered for the first time.
If the location is not set correctly the Config Admin may not send the update to the bundle.
:::
## Further Reading