org.apache.hadoop.hdfs.web.resources.Param Maven / Gradle / Ivy
/**
* 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.hdfs.web.resources;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Arrays;
import java.util.Comparator;
/** Base class of parameters. */
public abstract class Param> {
static final String NULL = "null";
static final Comparator> NAME_CMP = new Comparator>() {
@Override
public int compare(Param left, Param right) {
return left.getName().compareTo(right.getName());
}
};
/** Convert the parameters to a sorted String.
*
* @param separator URI parameter separator character
* @param parameters parameters to encode into a string
* @return the encoded URI string
*/
public static String toSortedString(final String separator,
final Param... parameters) {
Arrays.sort(parameters, NAME_CMP);
final StringBuilder b = new StringBuilder();
try {
for(Param p : parameters) {
if (p.getValue() != null) {
b.append(separator)
.append(URLEncoder.encode(p.getName(), "UTF-8"))
.append("=")
.append(URLEncoder.encode(p.getValueString(), "UTF-8"));
}
}
} catch (UnsupportedEncodingException e) {
// Sane systems know about UTF-8, so this should never happen.
throw new RuntimeException(e);
}
return b.toString();
}
/** The domain of the parameter. */
final D domain;
/** The actual parameter value. */
final T value;
Param(final D domain, final T value) {
this.domain = domain;
this.value = value;
}
/** @return the parameter value. */
public final T getValue() {
return value;
}
/** @return the parameter value as a string */
public abstract String getValueString();
/** @return the parameter name. */
public abstract String getName();
@Override
public String toString() {
return getName() + "=" + value;
}
/** Base class of parameter domains. */
static abstract class Domain {
/** Parameter name. */
final String paramName;
Domain(final String paramName) {
this.paramName = paramName;
}
/** @return the parameter name. */
public final String getParamName() {
return paramName;
}
/** @return a string description of the domain of the parameter. */
public abstract String getDomain();
/** @return the parameter value represented by the string. */
abstract T parse(String str);
/** Parse the given string.
* @return the parameter value represented by the string.
*/
public final T parse(final String varName, final String str) {
try {
return str != null && str.trim().length() > 0 ? parse(str) : null;
} catch(Exception e) {
throw new IllegalArgumentException("Failed to parse \"" + str
+ "\" for the parameter " + varName
+ ". The value must be in the domain " + getDomain(), e);
}
}
}
}