防止状态持续存在

默认情况下，所有物品阅读器和物品写手实现存储其当前状态 该州执行上下文在承诺之前。然而，这并不总是如此 期望的行为。例如，许多开发者选择将数据库设计为读取器 通过使用进程指示器实现“可重运行”。在输入数据中额外增加一列 说明是否已处理。当特定记录被读取时（或 写入）处理中的标志被翻转从false自true.SQL语句随后可以 包含一个额外的语句哪里从句，例如：其中 PROCESSED_IND = 假, 从而确保在重启时只返回未处理的记录。在 在这种情况下，最好不存储任何状态，例如当前行号， 因为重启后它无关紧要。因此，所有读者和作者都包含 “saveState”属性。spring-doc.cadn.net.cn

以下 bean 定义展示了如何在 Java 中防止状态持久化：spring-doc.cadn.net.cn

Java 配置
@Bean
public JdbcCursorItemReader playerSummarizationSource(DataSource dataSource) {
	return new JdbcCursorItemReaderBuilder<PlayerSummary>()
				.dataSource(dataSource)
				.rowMapper(new PlayerSummaryMapper())
				.saveState(false)
				.sql("SELECT games.player_id, games.year_no, SUM(COMPLETES),"
				  + "SUM(ATTEMPTS), SUM(PASSING_YARDS), SUM(PASSING_TD),"
				  + "SUM(INTERCEPTIONS), SUM(RUSHES), SUM(RUSH_YARDS),"
				  + "SUM(RECEPTIONS), SUM(RECEPTIONS_YARDS), SUM(TOTAL_TD)"
				  + "from games, players where players.player_id ="
				  + "games.player_id group by games.player_id, games.year_no")
				.build();

}

以下豆子定义展示了如何防止XML中的状态持久化：spring-doc.cadn.net.cn

XML 配置
<bean id="playerSummarizationSource" class="org.spr...JdbcCursorItemReader">
    <property name="dataSource" ref="dataSource" />
    <property name="rowMapper">
        <bean class="org.springframework.batch.samples.PlayerSummaryMapper" />
    </property>
    <property name="saveState" value="false" />
    <property name="sql">
        <value>
            SELECT games.player_id, games.year_no, SUM(COMPLETES),
            SUM(ATTEMPTS), SUM(PASSING_YARDS), SUM(PASSING_TD),
            SUM(INTERCEPTIONS), SUM(RUSHES), SUM(RUSH_YARDS),
            SUM(RECEPTIONS), SUM(RECEPTIONS_YARDS), SUM(TOTAL_TD)
            from games, players where players.player_id =
            games.player_id group by games.player_id, games.year_no
        </value>
    </property>
</bean>

这物品阅读器上述配置不在执行上下文为 任何其参与的处决。spring-doc.cadn.net.cn