Spring Batch ItemProcessor示例
原文： https://howtodoinjava.com/spring-batch/spring-batch-itemprocessor-example/
在读取输入并将其传递给写入器以写入文件/数据库之前，学习使用ItemProcessor添加业务逻辑。 请注意，虽然返回的数据类型可能不同于输入提供的数据类型，但这不是必需的。
从
ItemProcessor返回null表示不应继续处理该项目。
如何编写ItemProcessor
下面给出的ItemProcessor实现执行以下任务：
- 验证是否设置了
'id'字段。 - 验证
'id'字段是否可解析为整数。 - 验证
'id'字段是否为大于零的正整数。 - 如果验证失败，则返回
null，表示不处理记录。 - 如果验证成功，则按原样返回
Employee对象。
ValidationProcessor.java
import org.springframework.batch.item.ItemProcessor;
import com.howtodoinjava.demo.model.Employee;
public class ValidationProcessor implements ItemProcessor<Employee,Employee>
{
public Employee process(Employee employee) throws Exception
{
if (employee.getId() == null){
System.out.println("Missing employee id : " + employee.getId());
return null;
}
try
{
if(Integer.valueOf(employee.getId()) <= 0) {
System.out.println("Invalid employee id : " + employee.getId());
return null;
}
}
catch (NumberFormatException e) {
System.out.println("Invalid employee id : " + employee.getId());
return null;
}
return employee;
}
}
如何使用ItemProcessor
在步骤中设置 Tasklet 的过程中，应使用SimpleStepBuilder.processor()设置处理器实例。
BatchConfig.java
package com.howtodoinjava.demo.config;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.launch.support.RunIdIncrementer;
import org.springframework.batch.item.ItemProcessor;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.LineMapper;
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper;
import org.springframework.batch.item.file.mapping.DefaultLineMapper;
import org.springframework.batch.item.file.transform.DelimitedLineTokenizer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.Resource;
import com.howtodoinjava.demo.model.Employee;
@Configuration
@EnableBatchProcessing
public class BatchConfig {
@Autowired
private JobBuilderFactory jobBuilderFactory;
@Autowired
private StepBuilderFactory stepBuilderFactory;
@Value("/input/inputData.csv")
private Resource inputResource;
@Bean
public Job readCSVFilesJob() {
return jobBuilderFactory
.get("readCSVFilesJob")
.incrementer(new RunIdIncrementer())
.start(step1())
.build();
}
@Bean
public Step step1() {
return stepBuilderFactory
.get("step1")
.<Employee, Employee>chunk(1)
.reader(reader())
.processor(processor())
.writer(writer())
.build();
}
@Bean
public ItemProcessor<Employee, Employee> processor() {
return new ValidationProcessor();
}
@Bean
public FlatFileItemReader<Employee> reader() {
FlatFileItemReader<Employee> itemReader = new FlatFileItemReader<Employee>();
itemReader.setLineMapper(lineMapper());
itemReader.setLinesToSkip(1);
itemReader.setResource(inputResource);
return itemReader;
}
@Bean
public LineMapper<Employee> lineMapper() {
DefaultLineMapper<Employee> lineMapper = new DefaultLineMapper<Employee>();
DelimitedLineTokenizer lineTokenizer = new DelimitedLineTokenizer();
lineTokenizer.setNames(new String[] { "id", "firstName", "lastName" });
lineTokenizer.setIncludedFields(new int[] { 0, 1, 2 });
BeanWrapperFieldSetMapper<Employee> fieldSetMapper = new BeanWrapperFieldSetMapper<Employee>();
fieldSetMapper.setTargetType(Employee.class);
lineMapper.setLineTokenizer(lineTokenizer);
lineMapper.setFieldSetMapper(fieldSetMapper);
return lineMapper;
}
@Bean
public ConsoleItemWriter<Employee> writer() {
return new ConsoleItemWriter<Employee>();
}
}
ItemProcessor演示
我正在使用上述配置处理此 CSV。
inputData.csv
id,firstName,lastName
1,Lokesh,Gupta
2,Amit,Mishra
3,Pankaj,Kumar
abc,David,Miller
4,David,Walsh
开始作业并查看控制台。
Console
2018-07-11 14:59:00 INFO - Job: [SimpleJob: [name=readCSVFilesJob]] launched with the following parameters: [{JobID=1531301340005}]
2018-07-11 14:59:00 INFO - Executing step: [step1]
Employee [id=1, firstName=Lokesh, lastName=Gupta]
Employee [id=2, firstName=Amit, lastName=Mishra]
Employee [id=3, firstName=Pankaj, lastName=Kumar]
Invalid employee id : abc
Employee [id=4, firstName=David, lastName=Walsh]
2018-07-11 14:59:00 INFO - Job: [SimpleJob: [name=readCSVFilesJob]] completed with the following parameters: [{JobID=1531301340005}] and the following status: [COMPLETED]
将我的问题放在评论部分。
学习愉快！