io.opencensus.internal.StringUtil Maven / Gradle / Ivy
/*
* Copyright 2016-17, OpenCensus Authors
*
* Licensed 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 io.opencensus.internal;
/** Internal utility methods for working with tag keys, tag values, and metric names. */
public final class StringUtil {
public static final int MAX_LENGTH = 255;
public static final char UNPRINTABLE_CHAR_SUBSTITUTE = '_';
/**
* Transforms the given {@code String} into a valid tag key, tag value, or metric name. This
* method replaces non-printable characters with underscores and truncates to {@link
* StringUtil#MAX_LENGTH}.
*
* @param str the {@code String} to be sanitized.
* @return the {@code String} with all non-printable characters replaced by underscores, truncated
* to {@code MAX_LENGTH}.
*/
public static String sanitize(String str) {
if (str.length() > MAX_LENGTH) {
str = str.substring(0, MAX_LENGTH);
}
if (isPrintableString(str)) {
return str;
}
StringBuilder builder = new StringBuilder(str.length());
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
builder.append(isPrintableChar(ch) ? ch : UNPRINTABLE_CHAR_SUBSTITUTE);
}
return builder.toString();
}
/**
* Determines whether the {@code String} contains only printable characters.
*
* @param str the {@code String} to be validated.
* @return whether the {@code String} contains only printable characters.
*/
public static boolean isPrintableString(String str) {
for (int i = 0; i < str.length(); i++) {
if (!isPrintableChar(str.charAt(i))) {
return false;
}
}
return true;
}
private static boolean isPrintableChar(char ch) {
return ch >= ' ' && ch <= '~';
}
// Visible for testing
StringUtil() {
throw new AssertionError();
}
}