hadoop CopyFilter 源码
haddop CopyFilter 代码
文件路径：/hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/CopyFilter.java
/**
* 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 org.apache.hadoop.tools;
import java.lang.reflect.Constructor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
/**
* Interface for excluding files from DistCp.
*
*/
public abstract class CopyFilter {
private static final Logger LOG = LoggerFactory.getLogger(CopyFilter.class);
/**
* Default initialize method does nothing.
*/
public void initialize() {}
/**
* Predicate to determine if a file can be excluded from copy.
*
* @param path a Path to be considered for copying
* @return boolean, true to copy, false to exclude
*/
public abstract boolean shouldCopy(Path path);
/**
* Public factory method which returns the appropriate implementation of
* CopyFilter.
*
* @param conf DistCp configuration
* @return An instance of the appropriate CopyFilter
*/
public static CopyFilter getCopyFilter(Configuration conf) {
String filtersClassName = conf
.get(DistCpConstants.CONF_LABEL_FILTERS_CLASS);
if (filtersClassName != null) {
try {
Class<? extends CopyFilter> filtersClass = conf
.getClassByName(filtersClassName)
.asSubclass(CopyFilter.class);
filtersClassName = filtersClass.getName();
Constructor<? extends CopyFilter> constructor = filtersClass
.getDeclaredConstructor(Configuration.class);
return constructor.newInstance(conf);
} catch (Exception e) {
LOG.error(DistCpConstants.CLASS_INSTANTIATION_ERROR_MSG +
filtersClassName, e);
throw new RuntimeException(
DistCpConstants.CLASS_INSTANTIATION_ERROR_MSG +
filtersClassName, e);
}
} else {
return getDefaultCopyFilter(conf);
}
}
private static CopyFilter getDefaultCopyFilter(Configuration conf) {
String filtersFilename = conf.get(DistCpConstants.CONF_LABEL_FILTERS_FILE);
if (filtersFilename == null) {
return new TrueCopyFilter();
} else {
String filterFilename = conf.get(
DistCpConstants.CONF_LABEL_FILTERS_FILE);
return new RegexCopyFilter(filterFilename);
}
}
}
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