| 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.ExecutionContextUserSupport; |
| 22 | import org.springframework.batch.item.database.KeyCollector; |
| 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 | } |