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1   /*
2    * Copyright 2006-2013 the original author or authors.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.springframework.batch.core.step.skip;
17  
18  import java.io.FileNotFoundException;
19  import java.util.Collections;
20  import java.util.Map;
21  
22  import org.springframework.batch.core.Step;
23  import org.springframework.batch.core.StepExecution;
24  import org.springframework.batch.item.file.FlatFileParseException;
25  import org.springframework.classify.BinaryExceptionClassifier;
26  import org.springframework.classify.Classifier;
27  
28  /**
29   * <p>
30   * {@link SkipPolicy} that determines whether or not reading should continue
31   * based upon how many items have been skipped. This is extremely useful
32   * behavior, as it allows you to skip records, but will throw a
33   * {@link SkipLimitExceededException} if a set limit has been exceeded. For
34   * example, it is generally advisable to skip {@link FlatFileParseException}s,
35   * however, if the vast majority of records are causing exceptions, the file is
36   * likely bad.
37   * </p>
38   *
39   * <p>
40   * Furthermore, it is also likely that you only want to skip certain exceptions.
41   * {@link FlatFileParseException} is a good example of an exception you will
42   * likely want to skip, but a {@link FileNotFoundException} should cause
43   * immediate termination of the {@link Step}. A {@link Classifier} is used to
44   * determine whether a particular exception is skippable or not.
45   * </p>
46   *
47   * @author Ben Hale
48   * @author Lucas Ward
49   * @author Robert Kasanicky
50   * @author Dave Syer
51   * @author Dan Garrette
52   */
53  public class LimitCheckingItemSkipPolicy implements SkipPolicy {
54  
55  	private int skipLimit;
56  
57  	private Classifier<Throwable, Boolean> skippableExceptionClassifier;
58  
59  	/**
60  	 * Convenience constructor that assumes all exception types are fatal.
61  	 */
62  	public LimitCheckingItemSkipPolicy() {
63  		this(0, Collections.<Class<? extends Throwable>, Boolean> emptyMap());
64  	}
65  
66  	/**
67  	 * @param skipLimit the number of skippable exceptions that are allowed to
68  	 * be skipped
69  	 * @param skippableExceptions exception classes that can be skipped
70  	 * (non-critical)
71  	 */
72  	public LimitCheckingItemSkipPolicy(int skipLimit, Map<Class<? extends Throwable>, Boolean> skippableExceptions) {
73  		this(skipLimit, new BinaryExceptionClassifier(skippableExceptions));
74  	}
75  
76  	/**
77  	 * @param skipLimit the number of skippable exceptions that are allowed to
78  	 * be skipped
79  	 * @param skippableExceptionClassifier exception classifier for those that
80  	 * can be skipped (non-critical)
81  	 */
82  	public LimitCheckingItemSkipPolicy(int skipLimit, Classifier<Throwable, Boolean> skippableExceptionClassifier) {
83  		this.skipLimit = skipLimit;
84  		this.skippableExceptionClassifier = skippableExceptionClassifier;
85  	}
86  
87  	/**
88  	 * The absolute number of skips (of skippable exceptions) that can be
89  	 * tolerated before a failure.
90  	 *
91  	 * @param skipLimit the skip limit to set
92  	 */
93  	public void setSkipLimit(int skipLimit) {
94  		this.skipLimit = skipLimit;
95  	}
96  
97  	/**
98  	 * The classifier that will be used to decide on skippability. If an
99  	 * exception classifies as "true" then it is skippable, and otherwise not.
100 	 *
101 	 * @param skippableExceptionClassifier the skippableExceptionClassifier to
102 	 * set
103 	 */
104 	public void setSkippableExceptionClassifier(Classifier<Throwable, Boolean> skippableExceptionClassifier) {
105 		this.skippableExceptionClassifier = skippableExceptionClassifier;
106 	}
107 
108 	/**
109 	 * Set up the classifier through a convenient map from throwable class to
110 	 * boolean (true if skippable).
111 	 *
112 	 * @param skippableExceptions the skippable exceptions to set
113 	 */
114 	public void setSkippableExceptionMap(Map<Class<? extends Throwable>, Boolean> skippableExceptions) {
115 		this.skippableExceptionClassifier = new BinaryExceptionClassifier(skippableExceptions);
116 	}
117 
118 	/**
119 	 * Given the provided exception and skip count, determine whether or not
120 	 * processing should continue for the given exception. If the exception is
121 	 * not classified as skippable in the classifier, false will be returned. If
122 	 * the exception is classified as skippable and {@link StepExecution}
123 	 * skipCount is greater than the skipLimit, then a
124 	 * {@link SkipLimitExceededException} will be thrown.
125 	 */
126 	@Override
127 	public boolean shouldSkip(Throwable t, int skipCount) {
128 		if (skippableExceptionClassifier.classify(t)) {
129 			if (skipCount < skipLimit) {
130 				return true;
131 			}
132 			else {
133 				throw new SkipLimitExceededException(skipLimit, t);
134 			}
135 		}
136 		else {
137 			return false;
138 		}
139 	}
140 
141 }