春季批处理作业在使用MapFieldSet用于读取只有一列的TXT文件时会引发异常

Question

我只有一个只有一列的TXT文件：IDS和IDS由新行分开。 我想和读者一起阅读此文件，但是我认为我不应该使用DelimitedLineTokenizer，因为我的文件没有多个列。这是代码：

<bean id="idsReader" class="org.springframework.batch.item.file.FlatFileItemReader" scope="step">
        <property name="lineMapper">
            <bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
                <property name="lineTokenizer">
                    <bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
                        <property name="names" value="ids" />
                    </bean>
                </property>
                <property name="fieldSetMapper">
                    <bean class="IdsMapper" />
                </property>
            </bean>
        </property>
        <property name="resource" value="#{stepExecutionContext['fileResource']}" />
        <property name="encoding" value="UTF-8" />
    </bean>

public class IdsMapper implements FieldSetMapper<String> {

    @Override
    public String mapFieldSet(FieldSet fs) throws BindException {
        if (fs == null) {
            return null;
        }
        return fs.readString("ids");
    }

这是我收到的例外：

[jobTaskExecutor-15] ERROR Encountered an error executing step loadIds
Message: IdsMapper.mapFieldSet(Lorg/springframework/batch/item/file/transform/FieldSet;)Ljava/lang/String;
    Line | Method
->>   -1 | mapFieldSet                    in batch.model.IdsMapper
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|      7 | mapFieldSet                    in batch.model.IdsMapper$$ET3XDpZ2
|     -1 | mapFieldSet . . . . . . . . .  in batch.model.IdsMapper$$DT3XDpZ2
|     43 | mapLine                        in org.springframework.batch.item.file.mapping.DefaultLineMapper
|    180 | doRead . . . . . . . . . . . . in org.springframework.batch.item.file.FlatFileItemReader
|     88 | read                           in org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader

Answer 1

您可以使用自己的LineMapper实施：

    <bean id="idsReader" class="org.springframework.batch.item.file.FlatFileItemReader" scope="step">
        <property name="lineMapper">
            <bean class="com.example.TextFileLineMapper"/>
        </property>        
        <property name="resource" value="file:#{stepExecutionContext['resource']}"/>
        <property name="encoding" value="UTF-8" />
    </bean>

public class TextFileLineMapper implements LineMapper<TextFileDto> {

    @Override
    public TextFileDto mapLine(String line, int lineNumber) {
        TextFileDto textFileDto = new TextFileDto();
        textFileDto.setId(line);
        return textFileDto;
    }
}

public class TextFileDto {
    private String id;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
}