kafka CatCommandHandler 源码
kafka CatCommandHandler 代码
文件路径:/shell/src/main/java/org/apache/kafka/shell/CatCommandHandler.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.kafka.shell;
import net.sourceforge.argparse4j.inf.ArgumentParser;
import net.sourceforge.argparse4j.inf.Namespace;
import org.apache.kafka.shell.MetadataNode.DirectoryNode;
import org.apache.kafka.shell.MetadataNode.FileNode;
import org.jline.reader.Candidate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.PrintWriter;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
/**
* Implements the cat command.
*/
public final class CatCommandHandler implements Commands.Handler {
private static final Logger log = LoggerFactory.getLogger(CatCommandHandler.class);
public final static Commands.Type TYPE = new CatCommandType();
public static class CatCommandType implements Commands.Type {
private CatCommandType() {
}
@Override
public String name() {
return "cat";
}
@Override
public String description() {
return "Show the contents of metadata nodes.";
}
@Override
public boolean shellOnly() {
return false;
}
@Override
public void addArguments(ArgumentParser parser) {
parser.addArgument("targets").
nargs("+").
help("The metadata nodes to display.");
}
@Override
public Commands.Handler createHandler(Namespace namespace) {
return new CatCommandHandler(namespace.getList("targets"));
}
@Override
public void completeNext(MetadataNodeManager nodeManager, List<String> nextWords,
List<Candidate> candidates) throws Exception {
CommandUtils.completePath(nodeManager, nextWords.get(nextWords.size() - 1),
candidates);
}
}
private final List<String> targets;
public CatCommandHandler(List<String> targets) {
this.targets = targets;
}
@Override
public void run(Optional<InteractiveShell> shell,
PrintWriter writer,
MetadataNodeManager manager) throws Exception {
log.trace("cat " + targets);
for (String target : targets) {
manager.visit(new GlobVisitor(target, entryOption -> {
if (entryOption.isPresent()) {
MetadataNode node = entryOption.get().node();
if (node instanceof DirectoryNode) {
writer.println("cat: " + target + ": Is a directory");
} else if (node instanceof FileNode) {
FileNode fileNode = (FileNode) node;
writer.println(fileNode.contents());
}
} else {
writer.println("cat: " + target + ": No such file or directory.");
}
}));
}
}
@Override
public int hashCode() {
return targets.hashCode();
}
@Override
public boolean equals(Object other) {
if (!(other instanceof CatCommandHandler)) return false;
CatCommandHandler o = (CatCommandHandler) other;
if (!Objects.equals(o.targets, targets)) return false;
return true;
}
}
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