我想创建一个具有以下格式的平面文件:
Col1Name;Col2Name;Col3Name
one;23;20120912
two;28;20120712
如上所示,平面文件中的第一行是列名。
如何通过header回调来实现?
我看到如果输入文件是上述格式,则有一个选项可以忽略第一行:
<property name="firstLineIsHeader" value="true"/>
此外,这 Jira Issue表示我想要的已实现并关闭。但是,我找不到任何将第一行写为列名的示例。
<beans:bean id="MyFileItemWriter" class="com.nik.MyFileItemWriter" scope="step">
<beans:property name="delegate">
<beans:bean class="org.springframework.batch.item.file.FlatFileItemWriter">
<beans:property name="resource" value="file:MYFILE.dat" />
<beans:property name="lineAggregator">
<beans:bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
<beans:property name="delimiter" value=";" />
<beans:property name="fieldExtractor">
<beans:bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
<beans:property name="names" value="Col1Name, Col2Name, Col3Name" />
</beans:bean>
</beans:property>
</beans:bean>
</beans:property>
<beans:property name="headerCallback" ref="MyFileItemWriter" />
</beans:bean>
</beans:property>
</beans:bean>
我的 Item Writer 如下所示:
public class MyFileItemWriter implements ItemWriter<MyBean>, FlatFileHeaderCallback, ItemStream{
private FlatFileItemWriter<MyBean> delegate;
public void setDelegate(final FlatFileItemWriter<MyBean> delegate) {
this.delegate = delegate;
}
public void writeHeader(Writer writer) throws IOException {
}
public void write(List<? extends MyBean> items) throws Exception {
this.delegate.write(items);
}
public void close() throws ItemStreamException {
this.delegate.close();
}
public void open(ExecutionContext arg0) throws ItemStreamException {
this.delegate.open(arg0);
}
public void update(ExecutionContext arg0) throws ItemStreamException {
this.delegate.update(arg0);
}
}
感谢阅读!
最佳答案
创建一个扩展 FlatFileItemWriter 并仅实现构造函数的自定义类:
public class MyFlatFileWriter extends FlatFileItemWriter {
public MyFlatFileWriter (){
super.setHeaderCallback(new FlatFileHeaderCallback() {
public void writeHeader(Writer writer) throws IOException {
writer.write("Col1Name,Col2Name,Col3Name");
}
});
}
然后在bean配置类属性中使用这个类
关于java - Spring 批 : Writing column names as first line in flat file,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12388046/