1 | /* |
2 | * Copyright 2006-2007 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.item.database.support; |
17 | |
18 | import java.util.List; |
19 | |
20 | import org.springframework.batch.item.ExecutionContext; |
21 | import org.springframework.batch.item.database.KeyCollector; |
22 | import org.springframework.batch.item.util.ExecutionContextUserSupport; |
23 | import org.springframework.jdbc.core.JdbcTemplate; |
24 | import org.springframework.jdbc.core.RowMapper; |
25 | import org.springframework.jdbc.core.SingleColumnRowMapper; |
26 | import org.springframework.util.Assert; |
27 | import org.springframework.util.ClassUtils; |
28 | import org.springframework.util.StringUtils; |
29 | |
30 | /** |
31 | * <p> |
32 | * Jdbc {@link KeyCollector} implementation that only works for a single column key. A sql query must be passed in which |
33 | * will be used to return a list of keys. Each key will be mapped by a {@link RowMapper} that returns a mapped key. By |
34 | * default, the {@link SingleColumnRowMapper} is used, and will convert keys into well known types at runtime. It is |
35 | * extremely important to note that only one column should be mapped to an object and returned as a key. If multiple |
36 | * columns are returned as a key in this strategy, then restart will not function properly. Instead a strategy that |
37 | * supports keys comprised of multiple columns should be used. |
38 | * </p> |
39 | * |
40 | * <p> |
41 | * Restartability: Because the key is only one column, restart is made much more simple. Before each commit, the last |
42 | * processed key is returned to be stored as restart data. Upon restart, that same key is given back to restore from, |
43 | * using a separate 'RestartQuery'. This means that only the keys remaining to be processed are returned, rather than |
44 | * returning the original list of keys and iterating forward to that last committed point. |
45 | * </p> |
46 | * |
47 | * @author Lucas Ward |
48 | * @see SingleColumnRowMapper |
49 | */ |
50 | public class SingleColumnJdbcKeyCollector extends ExecutionContextUserSupport implements KeyCollector { |
51 | |
52 | private static final String RESTART_KEY = "key"; |
53 | |
54 | private JdbcTemplate jdbcTemplate; |
55 | |
56 | private String sql; |
57 | |
58 | private String restartSql; |
59 | |
60 | private RowMapper keyMapper = new SingleColumnRowMapper(); |
61 | |
62 | public SingleColumnJdbcKeyCollector() { |
63 | setName(ClassUtils.getShortName(SingleColumnJdbcKeyCollector.class)); |
64 | } |
65 | |
66 | /** |
67 | * Constructs a new instance using the provided jdbcTemplate and string representing the sql statement that should |
68 | * be used to retrieve keys. |
69 | * |
70 | * @param jdbcTemplate |
71 | * @param sql |
72 | * @throws IllegalArgumentException if jdbcTemplate is null. |
73 | * @throws IllegalArgumentException if sql string is empty or null. |
74 | */ |
75 | public SingleColumnJdbcKeyCollector(JdbcTemplate jdbcTemplate, String sql) { |
76 | this(); |
77 | Assert.notNull(jdbcTemplate, "JdbcTemplate must not be null."); |
78 | Assert.hasText(sql, "The sql statement must not be null or empty."); |
79 | this.jdbcTemplate = jdbcTemplate; |
80 | this.sql = sql; |
81 | } |
82 | |
83 | /* |
84 | * (non-Javadoc) |
85 | * |
86 | * @see org.springframework.batch.io.driving.KeyGenerationStrategy#retrieveKeys() |
87 | */ |
88 | public List retrieveKeys(ExecutionContext executionContext) { |
89 | |
90 | Assert.notNull(executionContext, "The ExecutionContext must not be null"); |
91 | |
92 | if (executionContext.containsKey(getKey(RESTART_KEY))) { |
93 | Assert.state(StringUtils.hasText(restartSql), "The restart sql query must not be null or empty" |
94 | + " in order to restart."); |
95 | return jdbcTemplate.query(restartSql, new Object[] { executionContext.get(getKey(RESTART_KEY)) }, keyMapper); |
96 | } else { |
97 | return jdbcTemplate.query(sql, keyMapper); |
98 | } |
99 | } |
100 | |
101 | /** |
102 | * Get the restart data representing the last processed key. |
103 | * |
104 | * @throws IllegalArgumentException if key is null. |
105 | */ |
106 | public void updateContext(Object key, ExecutionContext executionContext) { |
107 | Assert.notNull(key, "The key must not be null."); |
108 | Assert.notNull(executionContext, "The ExecutionContext must not be null"); |
109 | executionContext.put(getKey(RESTART_KEY), key); |
110 | } |
111 | |
112 | /* |
113 | * (non-Javadoc) |
114 | * |
115 | * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet() |
116 | */ |
117 | public void afterPropertiesSet() throws Exception { |
118 | Assert.notNull(jdbcTemplate, "JdbcTemplate must not be null."); |
119 | Assert.hasText(sql, "The DrivingQuery must not be null or empty."); |
120 | } |
121 | |
122 | /** |
123 | * Set the {@link RowMapper} to be used to map each key to an object. |
124 | * |
125 | * @param keyMapper |
126 | */ |
127 | public void setKeyMapper(RowMapper keyMapper) { |
128 | this.keyMapper = keyMapper; |
129 | } |
130 | |
131 | /** |
132 | * Set the SQL query to be used to return the remaining keys to be processed. |
133 | * |
134 | * @param restartSql |
135 | */ |
136 | public void setRestartSql(String restartSql) { |
137 | this.restartSql = restartSql; |
138 | } |
139 | |
140 | /** |
141 | * Set the SQL statement to be used to return the keys to be processed. |
142 | * |
143 | * @param sql |
144 | */ |
145 | public void setSql(String sql) { |
146 | this.sql = sql; |
147 | } |
148 | |
149 | /** |
150 | * Set the {@link JdbcTemplate} to be used. |
151 | * |
152 | * @param jdbcTemplate |
153 | */ |
154 | public void setJdbcTemplate(JdbcTemplate jdbcTemplate) { |
155 | this.jdbcTemplate = jdbcTemplate; |
156 | } |
157 | } |