Nutch 1.0 source code analysis [3] Plugin (2), nutchplugin

Nutch 1.0 source code analysis [3] Plugin (2), nutchplugin

Nutch 1.0 source code analysis [3] Plugin (2)

From: http://c.tieba.baidu.com/p/3439551436

In the URLNormalizers constructor, one sentence is not read:

This. ExtensionPoint = PluginRepository.Get(Conf). getExtensionPoint (

URLNormalizer.X_POINT_ID);

Let's take a look at the PluginRepository. get function:

Public static synchronizedPluginRepository get (Configuration conf ){

PluginRepository result =CACHE. Get (conf );

If(Result =Null){

Result =NewPluginRepository (conf );

CACHE. Put (conf, result );

}

ReturnResult;

}

First try to get from the CACHE. If it has not been cached, call the inrepository constructor:

PublicPluginRepository (Configuration conf)ThrowsRuntimeException {

FActivatedPlugins =NewHashMap <String, Plugin> ();

FExtensionPoints =NewHashMap <String, ExtensionPoint> ();

This. Conf = conf;

This. Auto = conf. getBoolean ("plugin. auto-activation ",True);

String [] pluginFolders = conf. getStrings ("plugin. folders ");

PluginManifestParsermanifestParser =NewPluginManifestParser (conf,

This);

Map <String, PluginDescriptor> allPlugins = manifestParser

. ParsePluginFolder (pluginFolders );

Pattern excludes = Pattern.Compile(Conf. get ("plugin. excludes ",""));

Pattern occurrence des = Pattern.Compile(Conf. get ("plugin. includes ",""));

Map <String, PluginDescriptor> filteredPlugins = filter (excludes,

Includes, allPlugins );

FRegisteredPlugins = getDependencyCheckedPlugins (filteredPlugins,

This. Auto? AllPlugins: filteredPlugins );

InstallExtensionPoints (fRegisteredPlugins );

Try{

InstallExtensions (fRegisteredPlugins );

}Catch(PluginRuntimeException e ){

LOG. Fatal (e. toString ());

ThrownewRuntimeException (e. getMessage ());

}

DisplayStatus ();

}

Copy the following description in "analysis of the Nutch plug-in system:

1. plugin. folders: directory where the plug-in is located. The default location is under the plugins directory.

<Property>

<Name> plugin. folders </name>

<Value> plugins </value>

</Property>

2. plugin. auto-activation: whether to enable the plug-in automatically when it is configured as a filter (I .e., not loaded) but dependent on other plug-ins. The default value is true.

<Property>

<Name> plugin. auto-activation </name>

<Value> true </value>

</Property>

3. plugin. Des: List of plug-in names to be included, which can be defined using regular expressions.

<Property>