spring batch中需要实现ItemProcessor接口来进行批量处理读入的数据。下面以批量把大小字母转化为小写字母为例
首先批量读字母,然后进行处理,最后打印出来,整个job作业配置如下
import java.util.Arrays;
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.item.ItemProcessor;
import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.support.ListItemReader;
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;
@EnableBatchProcessing
@Configuration
public class BatchConfig {
@Autowired
private StepBuilderFactory stepBuilderFactory;
@Autowired
private JobBuilderFactory jobBuilderFactory;
@Value("${spring.batch.chunk.size:3}")
private int chunkSize; //5
/*1、创建一个Job作业*/
@Bean
public Job itemProcessJob(){
return jobBuilderFactory.get("ItemProcessJob")
.start(chunkStep())
.build();
}
//2、创建一个step*/
@Bean
public Step chunkStep(){
return stepBuilderFactory.get("chunkStep")
.<String, String>chunk(chunkSize) //<String, String>表示输入是String类型,输出是String类型,不加会报错类型不匹配
.reader(listReader())
.processor(itemProcess())
.writer(list -> list.forEach(System.out::println))
.allowStartIfComplete(true)
.build();
}
//读
@Bean
public ItemReader<String> listReader(){
return new ListItemReader<>(Arrays.asList("A", "B", "C", "D", "E", "F", "G", "H", "I",
"J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T"));
}
//处理
@Bean
public ItemProcessor<String, String> itemProcess(){
return new LowerCaseItemProcess();
}
/*处理程序中,输入的是String类型, 输出的是String类型*/
private class LowerCaseItemProcess implements ItemProcessor<String, String>{
@Override
/*item表示输入的值;output表示处理后返回的值,都是String类型的*/
public String process(String item) throws Exception {
String output = item.toLowerCase(); //把大写字母转化为小写字母
return output;
}
}
}
运行该作业,输出内容如下:
……省略
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
从数据库中观察执行情况如下
最后一条就是执行信息,commit了5次,共读取20条信息,写入20条信息。由于chunkSize设置的是5,共20条数据,4次就读完20条数据了,但是spring batch不知道后面是否还有没有数据,不会终止,第5次读取下一条数据时,为空,然后再commit一次,终止。最后一次空也会commit一次,所以总共commit了5次。