/* * The MIT License * Copyright © 2014-2019 Ilkka Seppälä * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package com.iluwatar.mute; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.sql.SQLException; /** * Mute pattern is utilized when we need to suppress an exception due to an API flaw or in * situation when all we can do to handle the exception is to log it. * This pattern should not be used everywhere. It is very important to logically handle the * exceptions in a system, but some situations like the ones described above require this pattern, * so that we don't need to repeat *
*
* try {
* // code that may throwing exception we need to ignore or may never be thrown
* } catch (Exception ex) {
* // ignore by logging or throw error if unexpected exception occurs
* }
*
*
every time we need to ignore an exception.
*
*/
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Program entry point.
*
* @param args command line args.
* @throws Exception if any exception occurs
*/
public static void main(String[] args) throws Exception {
useOfLoggedMute();
useOfMute();
}
/*
* Typically used when the API declares some exception but cannot do so. Usually a
* signature mistake.In this example out is not supposed to throw exception as it is a
* ByteArrayOutputStream. So we utilize mute, which will throw AssertionError if unexpected
* exception occurs.
*/
private static void useOfMute() {
ByteArrayOutputStream out = new ByteArrayOutputStream();
Mute.mute(() -> out.write("Hello".getBytes()));
}
private static void useOfLoggedMute() throws SQLException {
Resource resource = null;
try {
resource = acquireResource();
utilizeResource(resource);
} finally {
closeResource(resource);
}
}
/*
* All we can do while failed close of a resource is to log it.
*/
private static void closeResource(Resource resource) {
Mute.loggedMute(() -> resource.close());
}
private static void utilizeResource(Resource resource) throws SQLException {
LOGGER.info("Utilizing acquired resource: {}", resource);
}
private static Resource acquireResource() throws SQLException {
return new Resource() {
@Override
public void close() throws IOException {
throw new IOException("Error in closing resource: " + this);
}
};
}
}