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1   /*
2    * Copyright 2002-2012 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  
17  package org.springframework.jdbc.support;
18  
19  import java.sql.SQLException;
20  
21  import org.apache.commons.logging.Log;
22  import org.apache.commons.logging.LogFactory;
23  
24  import org.springframework.dao.DataAccessException;
25  import org.springframework.jdbc.UncategorizedSQLException;
26  import org.springframework.util.Assert;
27  
28  /**
29   * Base class for {@link SQLExceptionTranslator} implementations that allow for
30   * fallback to some other {@link SQLExceptionTranslator}.
31   *
32   * @author Juergen Hoeller
33   * @since 2.5.6
34   */
35  public abstract class AbstractFallbackSQLExceptionTranslator implements SQLExceptionTranslator {
36  
37  	/** Logger available to subclasses */
38  	protected final Log logger = LogFactory.getLog(getClass());
39  
40  	private SQLExceptionTranslator fallbackTranslator;
41  
42  
43  	/**
44  	 * Override the default SQL state fallback translator
45  	 * (typically a {@link SQLStateSQLExceptionTranslator}).
46  	 */
47  	public void setFallbackTranslator(SQLExceptionTranslator fallback) {
48  		this.fallbackTranslator = fallback;
49  	}
50  
51  	/**
52  	 * Return the fallback exception translator, if any.
53  	 */
54  	public SQLExceptionTranslator getFallbackTranslator() {
55  		return this.fallbackTranslator;
56  	}
57  
58  
59  	/**
60  	 * Pre-checks the arguments, calls {@link #doTranslate}, and invokes the
61  	 * {@link #getFallbackTranslator() fallback translator} if necessary.
62  	 */
63  	@Override
64  	public DataAccessException translate(String task, String sql, SQLException ex) {
65  		Assert.notNull(ex, "Cannot translate a null SQLException");
66  		if (task == null) {
67  			task = "";
68  		}
69  		if (sql == null) {
70  			sql = "";
71  		}
72  
73  		DataAccessException dex = doTranslate(task, sql, ex);
74  		if (dex != null) {
75  			// Specific exception match found.
76  			return dex;
77  		}
78  		// Looking for a fallback...
79  		SQLExceptionTranslator fallback = getFallbackTranslator();
80  		if (fallback != null) {
81  			return fallback.translate(task, sql, ex);
82  		}
83  		// We couldn't identify it more precisely.
84  		return new UncategorizedSQLException(task, sql, ex);
85  	}
86  
87  	/**
88  	 * Template method for actually translating the given exception.
89  	 * <p>The passed-in arguments will have been pre-checked. Furthermore, this method
90  	 * is allowed to return {@code null} to indicate that no exception match has
91  	 * been found and that fallback translation should kick in.
92  	 * @param task readable text describing the task being attempted
93  	 * @param sql SQL query or update that caused the problem (may be {@code null})
94  	 * @param ex the offending {@code SQLException}
95  	 * @return the DataAccessException, wrapping the {@code SQLException};
96  	 * or {@code null} if no exception match found
97  	 */
98  	protected abstract DataAccessException doTranslate(String task, String sql, SQLException ex);
99  
100 
101 	/**
102 	 * Build a message {@code String} for the given {@link java.sql.SQLException}.
103 	 * <p>To be called by translator subclasses when creating an instance of a generic
104 	 * {@link org.springframework.dao.DataAccessException} class.
105 	 * @param task readable text describing the task being attempted
106 	 * @param sql the SQL statement that caused the problem (may be {@code null})
107 	 * @param ex the offending {@code SQLException}
108 	 * @return the message {@code String} to use
109 	 */
110 	protected String buildMessage(String task, String sql, SQLException ex) {
111 		return task + "; SQL [" + sql + "]; " + ex.getMessage();
112 	}
113 
114 }