org.springframework.boot.ansi.AnsiOutput Maven / Gradle / Ivy
/*
* Copyright 2012-2018 the original author or 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
*
* https://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.springframework.boot.ansi;
import java.util.Locale;
import org.springframework.util.Assert;
/**
* Generates ANSI encoded output, automatically attempting to detect if the terminal
* supports ANSI.
*
* @author Phillip Webb
*/
public abstract class AnsiOutput {
private static final String ENCODE_JOIN = ";";
private static Enabled enabled = Enabled.DETECT;
private static Boolean consoleAvailable;
private static Boolean ansiCapable;
private static final String OPERATING_SYSTEM_NAME = System.getProperty("os.name")
.toLowerCase(Locale.ENGLISH);
private static final String ENCODE_START = "\033[";
private static final String ENCODE_END = "m";
private static final String RESET = "0;" + AnsiColor.DEFAULT;
/**
* Sets if ANSI output is enabled.
* @param enabled if ANSI is enabled, disabled or detected
*/
public static void setEnabled(Enabled enabled) {
Assert.notNull(enabled, "Enabled must not be null");
AnsiOutput.enabled = enabled;
}
/**
* Sets if the System.console() is known to be available.
* @param consoleAvailable if the console is known to be available or {@code null} to
* use standard detection logic.
*/
public static void setConsoleAvailable(Boolean consoleAvailable) {
AnsiOutput.consoleAvailable = consoleAvailable;
}
static Enabled getEnabled() {
return AnsiOutput.enabled;
}
/**
* Encode a single {@link AnsiElement} if output is enabled.
* @param element the element to encode
* @return the encoded element or an empty string
*/
public static String encode(AnsiElement element) {
if (isEnabled()) {
return ENCODE_START + element + ENCODE_END;
}
return "";
}
/**
* Create a new ANSI string from the specified elements. Any {@link AnsiElement}s will
* be encoded as required.
* @param elements the elements to encode
* @return a string of the encoded elements
*/
public static String toString(Object... elements) {
StringBuilder sb = new StringBuilder();
if (isEnabled()) {
buildEnabled(sb, elements);
}
else {
buildDisabled(sb, elements);
}
return sb.toString();
}
private static void buildEnabled(StringBuilder sb, Object[] elements) {
boolean writingAnsi = false;
boolean containsEncoding = false;
for (Object element : elements) {
if (element instanceof AnsiElement) {
containsEncoding = true;
if (!writingAnsi) {
sb.append(ENCODE_START);
writingAnsi = true;
}
else {
sb.append(ENCODE_JOIN);
}
}
else {
if (writingAnsi) {
sb.append(ENCODE_END);
writingAnsi = false;
}
}
sb.append(element);
}
if (containsEncoding) {
sb.append(writingAnsi ? ENCODE_JOIN : ENCODE_START);
sb.append(RESET);
sb.append(ENCODE_END);
}
}
private static void buildDisabled(StringBuilder sb, Object[] elements) {
for (Object element : elements) {
if (!(element instanceof AnsiElement) && element != null) {
sb.append(element);
}
}
}
private static boolean isEnabled() {
if (enabled == Enabled.DETECT) {
if (ansiCapable == null) {
ansiCapable = detectIfAnsiCapable();
}
return ansiCapable;
}
return enabled == Enabled.ALWAYS;
}
private static boolean detectIfAnsiCapable() {
try {
if (Boolean.FALSE.equals(consoleAvailable)) {
return false;
}
if ((consoleAvailable == null) && (System.console() == null)) {
return false;
}
return !(OPERATING_SYSTEM_NAME.contains("win"));
}
catch (Throwable ex) {
return false;
}
}
/**
* Possible values to pass to {@link AnsiOutput#setEnabled}. Determines when to output
* ANSI escape sequences for coloring application output.
*/
public enum Enabled {
/**
* Try to detect whether ANSI coloring capabilities are available. The default
* value for {@link AnsiOutput}.
*/
DETECT,
/**
* Enable ANSI-colored output.
*/
ALWAYS,
/**
* Disable ANSI-colored output.
*/
NEVER
}
}