org.apache.hadoop.hive.common.StringableMap Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.common;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
/**
* A utility class that can convert a HashMap of Properties into a colon separated string,
* and can take the same format of string and convert it to a HashMap of Properties.
*/
public class StringableMap extends HashMap {
public StringableMap(String s) {
String[] parts = s.split(":", 2);
// read that many chars
int numElements = Integer.parseInt(parts[0]);
s = parts[1];
for (int i = 0; i < numElements; i++) {
// Get the key String.
parts = s.split(":", 2);
int len = Integer.parseInt(parts[0]);
String key = ""; // Default is now an empty string.
if (len > 0) key = parts[1].substring(0, len);
// Please check the toString() method of this class.
// null has -1 as length and empty String has 0.
else if (len < 0) {
key = null;
len = 0; // Set 0 to 'len' for null-valued key
// since only len exists for null-valued key from the given String "s".
}
// Get the value String for the key
parts = parts[1].substring(len).split(":", 2);
len = Integer.parseInt(parts[0]);
String value = "";
if (len > 0) value = parts[1].substring(0, len);
else if (len < 0) {
value = null;
len = 0; // Set 0 to 'len' since only len exists.
}
// Put the entry into the HashMap.
put(key, value);
// Move to the next substring to process.
s = parts[1].substring(len);
}
}
public StringableMap(Map m) {
super(m);
}
@Override
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append(size());
buf.append(':');
if (size() > 0) {
for (Map.Entry entry : entrySet()) {
// Append the key String to the output StringBuilder.
// Note that null is saved as -1 in length, and that empty String as 0.
int length = (entry.getKey() == null) ? -1 : entry.getKey().length();
buf.append(length);
buf.append(':');
if (length > 0) buf.append(entry.getKey());
// Append the value String to the output StringBuilder.
// Note that null is saved as -1 in length, and that empty String as 0.
length = (entry.getValue() == null) ? -1 : entry.getValue().length();
buf.append(length);
buf.append(':');
if (length > 0) {
buf.append(entry.getValue());
}
}
}
return buf.toString();
}
public Properties toProperties() {
Properties props = new Properties();
props.putAll(this);
return props;
}
}