前言
本文主要講述基本的批處理任務的解決方案。
創建業務數據
手動創建一個文件來模擬業務數據
src/main/resources/sample-data.properties
Jill,Doe
Joe,Doe
Justin,Doe
Jane,Doe
John,Doe
編寫SQL腳本
接下來寫一個sql腳本創建一個表來存儲數據
src/main/resources/schema-all.sql
DROP TABLE people IF EXISTS;
CREATE TABLE people (
person_id BIGINT IDENTITY NOT NULL PRIMARY KEY,
first_name VARCHAR(20),
last_name VARCHAR(20)
);
Spring Boot運行模式-@@platform@@ @。sql在啓動時自動執行。-all是所有平臺的默認值。
創建實體類
接下來寫一個類來表示每行的數據
package com.yjn.bean;
public class Person {
private String lastName;
private String firstName;
public Person() {
}
public Person(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Override
public String toString() {
return "firstName: " + firstName + ", lastName: " + lastName;
}
}
創建一箇中間處理器
批處理中的一個常見範例是獲取數據,轉換數據,然後將其輸出到其他地方。這裏編寫一個簡單的轉換器,將名稱轉換爲大寫。
package com.yjn.batch;
import com.yjn.bean.Person;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobExecutionListener;
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.database.BeanPropertyItemSqlParameterSourceProvider;
import org.springframework.batch.item.database.JdbcBatchItemWriter;
import org.springframework.batch.item.database.builder.JdbcBatchItemWriterBuilder;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
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.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.jdbc.core.JdbcTemplate;
import javax.sql.DataSource;
@Configuration
@EnableBatchProcessing
public class BatchConfiguration {
@Autowired
public JobBuilderFactory jobBuilderFactory;
@Autowired
public StepBuilderFactory stepBuilderFactory;
@Bean
public FlatFileItemReader<Person> reader() {
return new FlatFileItemReaderBuilder<Person>()
.name("personItemReader")
.resource(new ClassPathResource("sample-data.csv"))
.delimited()
.names(new String[]{"firstName", "lastName"})
.fieldSetMapper(new BeanWrapperFieldSetMapper<Person>() {{
setTargetType(Person.class);
}})
.build();
}
@Bean
public PersonItemProcessor processor() {
return new PersonItemProcessor();
}
@Bean
public JdbcBatchItemWriter<Person> writer(DataSource dataSource) {
return new JdbcBatchItemWriterBuilder<Person>()
.itemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>())
.sql("INSERT INTO people (first_name, last_name) VALUES (:firstName, :lastName)")
.dataSource(dataSource)
.build();
}
@Bean
public Job importUserJob(JobCompletionNotificationListener listener, Step step1) {
return jobBuilderFactory.get("importUserJob")
.incrementer(new RunIdIncrementer())
.listener(listener)
.flow(step1)
.end()
.build();
}
@Bean
public Step step1(JdbcBatchItemWriter<Person> writer) {
return stepBuilderFactory.get("step1")
.<Person, Person> chunk(10)
.reader(reader())
.processor(processor())
.writer(writer)
.build();
}
}
對於初學者來說,@EnableBatchProcessing註釋添加了很多任務支持的關鍵bean,並節省了大量的輔助工作。這個例子使用一個基於內存的數據庫(由@EnableBatchProcessing提供),這意味着當它完成時,數據就消失了。
第一個代碼塊定義輸入、處理器和輸出。
reader()創建一個ItemReader。它查找一個名爲sample-data.csv的文件,並解析每個行項目,其中包含足夠的信息將其轉換爲Person。
processor()創建前面定義的PersonItemProcessor的一個實例,用於大寫數據。
write(DataSource)創建一個ItemWriter。這一個針對JDBC目標,並自動獲取由@EnableBatchProcessing創建的數據源的副本。它包括插入由Java bean屬性驅動的單個人所需的SQL語句。
@Bean
public Job importUserJob(JobCompletionNotificationListener listener, Step step1) {
return jobBuilderFactory.get("importUserJob")
.incrementer(new RunIdIncrementer())
.listener(listener)
.flow(step1)
.end()
.build();
}
@Bean
public Step step1(JdbcBatchItemWriter<Person> writer) {
return stepBuilderFactory.get("step1")
.<Person, Person> chunk(10)
.reader(reader())
.processor(processor())
.writer(writer)
.build();
}
第一個方法定義作業,第二個方法定義單個步驟。作業是由步驟構建的,其中每個步驟都包含一個讀取器、一個處理器和一個寫入器。
在這個作業定義中,你需要一個遞增器,因爲作業使用數據庫來維護執行狀態。然後列出每個步驟,其中這個作業只有一個步驟。作業結束,Java API生成一個配置完美的作業。
在步驟定義中,定義一次要寫多少數據。在本例中,它一次寫入多達10條記錄。接下來,使用前面注入的位配置讀取器、處理器和寫入器。
package com.yjn.batch;
import com.yjn.bean.Person;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.core.BatchStatus;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.listener.JobExecutionListenerSupport;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;
@Component
public class JobCompletionNotificationListener extends JobExecutionListenerSupport {
private static final Logger log = LoggerFactory.getLogger(JobCompletionNotificationListener.class);
private final JdbcTemplate jdbcTemplate;
@Autowired
public JobCompletionNotificationListener(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
@Override
public void afterJob(JobExecution jobExecution) {
if(jobExecution.getStatus() == BatchStatus.COMPLETED) {
log.info("!!! JOB FINISHED! Time to verify the results");
jdbcTemplate.query("SELECT first_name, last_name FROM people",
(rs, row) -> new Person(
rs.getString(1),
rs.getString(2))
).forEach(person -> log.info("Found <" + person + "> in the database."));
}
}
}