1 | /** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one |
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3 | * or more contributor license agreements. See the NOTICE file |
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4 | * distributed with this work for additional information |
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5 | * regarding copyright ownership. The ASF licenses this file |
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6 | * to you under the Apache License, Version 2.0 (the |
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7 | * "License"); you may not use this file except in compliance |
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8 | * with the License. You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | */ |
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18 | |
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19 | package org.apache.hadoop.ipc; |
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20 | |
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21 | import java.io.IOException; |
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22 | import java.lang.reflect.Constructor; |
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23 | |
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24 | import org.xml.sax.Attributes; |
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25 | import org.znerd.xmlenc.XMLOutputter; |
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26 | |
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27 | public class RemoteException extends IOException { |
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28 | /** For java.io.Serializable */ |
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29 | private static final long serialVersionUID = 1L; |
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30 | |
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31 | private String className; |
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32 | |
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33 | public RemoteException(String className, String msg) { |
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34 | super(msg); |
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35 | this.className = className; |
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36 | } |
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37 | |
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38 | public String getClassName() { |
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39 | return className; |
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40 | } |
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41 | |
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42 | /** |
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43 | * If this remote exception wraps up one of the lookupTypes |
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44 | * then return this exception. |
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45 | * <p> |
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46 | * Unwraps any IOException. |
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47 | * |
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48 | * @param lookupTypes the desired exception class. |
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49 | * @return IOException, which is either the lookupClass exception or this. |
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50 | */ |
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51 | public IOException unwrapRemoteException(Class<?>... lookupTypes) { |
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52 | if(lookupTypes == null) |
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53 | return this; |
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54 | for(Class<?> lookupClass : lookupTypes) { |
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55 | if(!lookupClass.getName().equals(getClassName())) |
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56 | continue; |
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57 | try { |
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58 | return instantiateException(lookupClass.asSubclass(IOException.class)); |
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59 | } catch(Exception e) { |
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60 | // cannot instantiate lookupClass, just return this |
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61 | return this; |
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62 | } |
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63 | } |
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64 | // wrapped up exception is not in lookupTypes, just return this |
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65 | return this; |
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66 | } |
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67 | |
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68 | /** |
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69 | * Instantiate and return the exception wrapped up by this remote exception. |
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70 | * |
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71 | * <p> This unwraps any <code>Throwable</code> that has a constructor taking |
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72 | * a <code>String</code> as a parameter. |
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73 | * Otherwise it returns this. |
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74 | * |
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75 | * @return <code>Throwable |
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76 | */ |
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77 | public IOException unwrapRemoteException() { |
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78 | try { |
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79 | Class<?> realClass = Class.forName(getClassName()); |
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80 | return instantiateException(realClass.asSubclass(IOException.class)); |
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81 | } catch(Exception e) { |
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82 | // cannot instantiate the original exception, just return this |
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83 | } |
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84 | return this; |
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85 | } |
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86 | |
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87 | private IOException instantiateException(Class<? extends IOException> cls) |
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88 | throws Exception { |
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89 | Constructor<? extends IOException> cn = cls.getConstructor(String.class); |
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90 | cn.setAccessible(true); |
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91 | String firstLine = this.getMessage(); |
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92 | int eol = firstLine.indexOf('\n'); |
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93 | if (eol>=0) { |
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94 | firstLine = firstLine.substring(0, eol); |
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95 | } |
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96 | IOException ex = cn.newInstance(firstLine); |
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97 | ex.initCause(this); |
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98 | return ex; |
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99 | } |
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100 | |
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101 | /** Write the object to XML format */ |
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102 | public void writeXml(String path, XMLOutputter doc) throws IOException { |
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103 | doc.startTag(RemoteException.class.getSimpleName()); |
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104 | doc.attribute("path", path); |
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105 | doc.attribute("class", getClassName()); |
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106 | String msg = getLocalizedMessage(); |
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107 | int i = msg.indexOf("\n"); |
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108 | if (i >= 0) { |
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109 | msg = msg.substring(0, i); |
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110 | } |
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111 | doc.attribute("message", msg.substring(msg.indexOf(":") + 1).trim()); |
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112 | doc.endTag(); |
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113 | } |
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114 | |
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115 | /** Create RemoteException from attributes */ |
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116 | public static RemoteException valueOf(Attributes attrs) { |
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117 | return new RemoteException(attrs.getValue("class"), |
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118 | attrs.getValue("message")); |
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119 | } |
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120 | } |
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