001/* 002 * Copyright 2012-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.boot.diagnostics; 018 019import org.springframework.core.ResolvableType; 020 021/** 022 * Abstract base class for most {@code FailureAnalyzer} implementations. 023 * 024 * @param <T> the type of exception to analyze 025 * @author Andy Wilkinson 026 * @author Phillip Webb 027 * @since 1.4.0 028 */ 029public abstract class AbstractFailureAnalyzer<T extends Throwable> 030 implements FailureAnalyzer { 031 032 @Override 033 public FailureAnalysis analyze(Throwable failure) { 034 T cause = findCause(failure, getCauseType()); 035 if (cause != null) { 036 return analyze(failure, cause); 037 } 038 return null; 039 } 040 041 /** 042 * Returns an analysis of the given {@code rootFailure}, or {@code null} if no 043 * analysis was possible. 044 * @param rootFailure the root failure passed to the analyzer 045 * @param cause the actual found cause 046 * @return the analysis or {@code null} 047 */ 048 protected abstract FailureAnalysis analyze(Throwable rootFailure, T cause); 049 050 /** 051 * Return the cause type being handled by the analyzer. By default the class generic 052 * is used. 053 * @return the cause type 054 */ 055 @SuppressWarnings("unchecked") 056 protected Class<? extends T> getCauseType() { 057 return (Class<? extends T>) ResolvableType 058 .forClass(AbstractFailureAnalyzer.class, getClass()).resolveGeneric(); 059 } 060 061 @SuppressWarnings("unchecked") 062 protected final <E extends Throwable> E findCause(Throwable failure, Class<E> type) { 063 while (failure != null) { 064 if (type.isInstance(failure)) { 065 return (E) failure; 066 } 067 failure = failure.getCause(); 068 } 069 return null; 070 } 071 072}