001/* 002 * Copyright 2002-2017 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 * https://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.core; 018 019/** 020 * Helper class for implementing exception classes which are capable of 021 * holding nested exceptions. Necessary because we can't share a base 022 * class among different exception types. 023 * 024 * <p>Mainly for use within the framework. 025 * 026 * @author Juergen Hoeller 027 * @since 2.0 028 * @see NestedRuntimeException 029 * @see NestedCheckedException 030 * @see NestedIOException 031 * @see org.springframework.web.util.NestedServletException 032 */ 033public abstract class NestedExceptionUtils { 034 035 /** 036 * Build a message for the given base message and root cause. 037 * @param message the base message 038 * @param cause the root cause 039 * @return the full exception message 040 */ 041 public static String buildMessage(String message, Throwable cause) { 042 if (cause == null) { 043 return message; 044 } 045 StringBuilder sb = new StringBuilder(64); 046 if (message != null) { 047 sb.append(message).append("; "); 048 } 049 sb.append("nested exception is ").append(cause); 050 return sb.toString(); 051 } 052 053 /** 054 * Retrieve the innermost cause of the given exception, if any. 055 * @param original the original exception to introspect 056 * @return the innermost exception, or {@code null} if none 057 * @since 4.3.9 058 */ 059 public static Throwable getRootCause(Throwable original) { 060 if (original == null) { 061 return null; 062 } 063 Throwable rootCause = null; 064 Throwable cause = original.getCause(); 065 while (cause != null && cause != rootCause) { 066 rootCause = cause; 067 cause = cause.getCause(); 068 } 069 return rootCause; 070 } 071 072 /** 073 * Retrieve the most specific cause of the given exception, that is, 074 * either the innermost cause (root cause) or the exception itself. 075 * <p>Differs from {@link #getRootCause} in that it falls back 076 * to the original exception if there is no root cause. 077 * @param original the original exception to introspect 078 * @return the most specific cause (never {@code null}) 079 * @since 4.3.9 080 */ 081 public static Throwable getMostSpecificCause(Throwable original) { 082 Throwable rootCause = getRootCause(original); 083 return (rootCause != null ? rootCause : original); 084 } 085 086}