ai.platon.pulsar.skeleton.crawl.parse.ParserConfigReader.kt Maven / Gradle / Ivy
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/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
*
* http://www.apache.org/licenses/LICENSE-2.0
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ai.platon.pulsar.skeleton.crawl.parse
import ai.platon.pulsar.common.ResourceLoader
import ai.platon.pulsar.common.config.CapabilityTypes
import ai.platon.pulsar.common.config.ImmutableConfig
import org.slf4j.LoggerFactory
import org.w3c.dom.Document
import org.w3c.dom.Element
import org.xml.sax.InputSource
import org.xml.sax.SAXException
import java.io.IOException
import javax.xml.parsers.DocumentBuilderFactory
import javax.xml.parsers.ParserConfigurationException
/**
* A reader to load the information stored in the `parse-plugins.xml` file.
*/
class ParserConfigReader {
/**
* the parse-plugins file
*/
private lateinit var parseConfigFile: String
private val notDefinedParsers = mutableListOf()
/**
* Reads the `parse-plugins.xml` file and returns the
* [ParserConfig] defined by it.
*
* @return A [ParserConfig] specified by the
* `parse-plugins.xml` file.
*/
fun parse(conf: ImmutableConfig): ParserConfig {
val parserConfig = ParserConfig()
val resourcePrefix = conf[CapabilityTypes.LEGACY_CONFIG_PROFILE, ""]
val fileResource = conf[PARSE_PLUGINS_FILE, "parse-plugins.xml"]
var document: Document? = null
try {
ResourceLoader.getResourceAsReader(fileResource, resourcePrefix).use { reader ->
val inputSource = InputSource(reader)
val parser = DocumentBuilderFactory.newInstance().newDocumentBuilder()
document = parser.parse(inputSource)
}
} catch (e: IOException) {
LOG.error("Failed to find resource $fileResource")
return parserConfig
} catch (e: ParserConfigurationException) {
LOG.warn("Unable to parse [$parseConfigFile]", e)
return parserConfig
} catch (e: SAXException) {
LOG.warn("Unable to parse [$parseConfigFile]", e)
return parserConfig
} catch (e: Throwable) {
LOG.warn("Unable to parse [$parseConfigFile], unexpected exception", e)
return parserConfig
}
val parsePlugins = document!!.documentElement
// build up the alias hash map
val aliases = getAliases(parsePlugins)
// And store it on the parse plugin list
parserConfig.aliases = aliases
// get all the mime type nodes
val mimeTypes = parsePlugins.getElementsByTagName("mimeType")
// iterate through the mime types
for (i in 0 until mimeTypes.length) {
val mimeType = mimeTypes.item(i) as Element
val mimeTypeStr = mimeType.getAttribute("name")
// for each mimeType, get the plugin list
val parserNodes = mimeType.getElementsByTagName("parser")
// iterate through the plugins, add them in order read
// OR if they have a special order="" attribute, then hold those in
// a separate list, and then insert them into the final list at the
// order specified
if (parserNodes.length > 0) {
val parserClasses = mutableListOf()
for (j in 0 until parserNodes.length) {
val parserNode = parserNodes.item(j) as Element
val parserId = parserNode.getAttribute("id")
val parserClass = aliases[parserId]
if (parserClass == null) {
notDefinedParsers.add(parserId)
continue
}
parserClasses.add(parserClass)
}
// now add the plugin list and map it to this mimeType
if (parserClasses.isNotEmpty()) {
parserConfig.setParsers(mimeTypeStr, parserClasses)
}
} else {
LOG.warn("No plugins defined for mime type: $mimeTypeStr, continuing parse")
}
}
return parserConfig
}
private fun getAliases(parsePluginsRoot: Element): Map {
val aliases: MutableMap = HashMap()
val aliasRoot = parsePluginsRoot.getElementsByTagName("aliases")
if (aliasRoot.length == 0) {
if (LOG.isWarnEnabled) {
LOG.warn("No aliases defined in parse-plugins.xml!")
}
return aliases
}
if (aliasRoot.length > 1) { // log a warning, but try and continue processing
if (LOG.isWarnEnabled) {
LOG.warn("There should only be one \"aliases\" tag in parse-plugins.xml")
}
}
val aliasRootElem = aliasRoot.item(0) as Element
val aliasElements = aliasRootElem.getElementsByTagName("alias")
if (aliasElements.length > 0) {
for (i in 0 until aliasElements.length) {
val aliasElem = aliasElements.item(i) as Element
val name = aliasElem.getAttribute("name")
val clazz = aliasElem.getAttribute("class")
aliases[name] = clazz
}
}
return aliases
}
companion object {
/* our log stream */
val LOG = LoggerFactory.getLogger(ParserConfigReader::class.java)
/**
* The property name of the parse-plugins location
*/
const val PARSE_PLUGINS_FILE = "parse.plugin.file"
}
}