Spring Batch 初始化数据，清空数据的做法

这两天用了一下Spring Batch来导数据，感觉是个很强大的工具。网上的资料很多，没看到连续运行的示例。从mkong和spring官网上搞了几段代码，在本地跑了一下发现几个问题：

1. initialize-database执行官方的drop table失败

报权限问题，检查了一下，无法就是清理spring batch任务表中的数据

DROP TABLE  BATCH_STEP_EXECUTION_CONTEXT ;DROP TABLE  BATCH_JOB_EXECUTION_CONTEXT ;DROP TABLE  BATCH_STEP_EXECUTION ;DROP TABLE  BATCH_JOB_EXECUTION_PARAMS ;DROP TABLE  BATCH_JOB_EXECUTION ;DROP TABLE  BATCH_JOB_INSTANCE ;DROP TABLE  BATCH_STEP_EXECUTION_SEQ ;DROP TABLE  BATCH_JOB_EXECUTION_SEQ ;DROP TABLE  BATCH_JOB_SEQ ;

其实多次执行的时候不用drop这个表，所以将这块去掉了，改成了由

<jdbc:script location="classpath:init.sql" />

调用一段本地的脚本

2. 连续运行job失败

这个是传参的问题，每次给JobParameters设置不同的参数才能顺利的连续运行。

HashMap<String, JobParameter> parameters = new HashMap<String, JobParameter>();parameters.put("currentTime", new JobParameter(System.currentTimeMillis()));JobExecution execution = jobLauncher.run(job, new JobParameters(parameters));

加了个当前时间，搞定

3.第二次执行导入的时候报主键错误

因为每次都是完全拷贝，没做检查，所以在插入前有必要清理所有的内容。可是程序在多次运行（注意，是连续运行）的情况下，只会运行一次initialize-database的内容。

翻遍了例子所有的step都要有reader和writer。于是手动写了一个Reader和Writer来跑清理的过程。注意还要写一个Listener，不然会一直执行下去，这个是用来让计数器归位的。

job的配置

<batch:tasklet transaction-manager="transactionManagerJob">    <batch:chunk reader="deleteReader" writer="deleteWriter"commit-interval="1">    </batch:chunk>    <batch:listeners>        <batch:listener ref="resettingListener"/>    </batch:listeners></batch:tasklet>

reader的配置

<beans:bean id="deleteReader" class="xxx.InitReader">    <property name="limit" value="1"/></beans:bean>

writer的配置

<beans:bean id="deleteWriter" class="xxxx.InitWriter">    <property name="dataSource" ref="targetDataSource" />    <property name="sql"value="DELETE FROM XXX;DELETE FROM YYY;" /></beans:bean>

listener的配置

<beans:bean id="resettingListener" class="xxx.InitResettingListener">    <beans:property name="reader" ref="deleteReader" /></beans:bean>

reader的代码

public class InitReader extends ItemReaderAdapter<Object> {private int limit = 1;private int counter = 0;public Object read() throws Exception, UnexpectedInputException, ParseException {if(counter<limit){counter++;return new Object();}return null;}/** * @param limit number of items that will be generated * (null returned on consecutive calls). */public void setLimit(int limit) {this.limit = limit;}public int getCounter() {return counter;}public int getLimit() {return limit;}public void resetCounter(){this.counter = 0;} public void afterPropertiesSet() throws Exception {     Assert.notNull(limit, "limit must be set"); }}

writer的代码

public class InitWriter extends ItemWriterAdapter<Object>{private DriverManagerDataSource dataSource;private String sql;public DriverManagerDataSource getDataSource() {return dataSource;}public void setDataSource(DriverManagerDataSource dataSource) {this.dataSource = dataSource;}public String getSql() {return sql;}public void setSql(String sql) {this.sql = sql;}public void write(List<? extends Object> items) throws Exception {//System.out.println("init write delete");Connection connection = dataSource.getConnection();PreparedStatement preparedStatement=connection.prepareStatement(sql);preparedStatement.executeUpdate();System.out.println("init delete data complete.");}public void afterPropertiesSet() throws Exception {    Assert.notNull(dataSource, "dataSource limit must be set");    Assert.notNull(sql, "sql limit must be set");}}

listener的代码

public class InitResettingListener extends StepExecutionListenerSupport implements InitializingBean {private InitReader reader;public ExitStatus afterStep(StepExecution stepExecution) {this.reader.resetCounter();return null;}public void setReader(InitReader reader) {this.reader = reader;}public void afterPropertiesSet() throws Exception {Assert.notNull(this.reader, "The 'reader' must be set.");}}

搞定！！！