Spring Boot批量服务

批处理服务是在单个任务中执行多个命令的过程。 在本章中，将学习如何在Spring Boot应用程序中创建批处理服务。

在开始学习之前，请考虑一个示例，如何将CSV文件内容保存到HSQLDB中。

要创建批处理服务程序，需要在构建配置文件中添加Spring Boot Starter Batch依赖项和HSQLDB依赖项。

Maven用户可以在pom.xml 文件中添加以下依赖项。

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-batch</artifactId>
</dependency>
<dependency>
   <groupId>org.hsqldb</groupId>
   <artifactId>hsqldb</artifactId>
</dependency>

XML

Gradle用户可以在build.gradle 文件中添加以下依赖项。

compile("org.springframework.boot:spring-boot-starter-batch")
compile("org.hsqldb:hsqldb")

现在，在资源目录 - src/main/resources 下添加简单的CSV数据文件，并将文件命名为file.csv，如图所示 -

Max,Su
Da, Lee
Sanfeng, Zhang

接下来，为HSQLDB编写一个SQL脚本 - 在资源目(src/main/resources)录下创建一个文件: request_fail_hystrix_timeout

DROP TABLE USERS IF EXISTS;
CREATE TABLE USERS  (
   user_id BIGINT IDENTITY NOT NULL PRIMARY KEY,
   first_name VARCHAR(20),
   last_name VARCHAR(20)
);

SQL

创建一个POJO类，如图所示 -

package com.yiibai.batchservicedemo;
public class User {
   private String lastName;
   private String firstName;

   public User() {
   }
   public User(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;
   }   
}

Java

现在，创建一个中间处理器，在从CSV文件读取数据之后和将数据写入SQL之前执行操作。

package com.yiibai.batchservicedemo;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.item.ItemProcessor;

public class UserItemProcessor implements ItemProcessor<User, User> {
   private static final Logger log = LoggerFactory.getLogger(UserItemProcessor.class);

   @Override
   public User process(final User user) throws Exception {
      final String firstName = user.getFirstName().toUpperCase();
      final String lastName = user.getLastName().toUpperCase();
      final User transformedPerson = new User(firstName, lastName);

      log.info("Converting (" + user + ") into (" + transformedPerson + ")");
      return transformedPerson;
   }
}

Java

创建一个Batch配置文件，从CSV读取数据并写入SQL文件，如下所示。需要在配置类文件中添加@EnableBatchProcessing注释。 @EnableBatchProcessing注释用于启用Spring Boot应用程序的批处理操作。

package com.yiibai.batchservicedemo;

import javax.sql.DataSource;
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.database.BeanPropertyItemSqlParameterSourceProvider;
import org.springframework.batch.item.database.JdbcBatchItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
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;

@Configuration
@EnableBatchProcessing
public class BatchConfiguration {
   @Autowired
   public JobBuilderFactory jobBuilderFactory;

   @Autowired
   public StepBuilderFactory stepBuilderFactory;

   @Autowired
   public DataSource dataSource;

   @Bean
   public FlatFileItemReader<User> reader() {
      FlatFileItemReader<User> reader = new FlatFileItemReader<User>();
      reader.setResource(new ClassPathResource("file.csv"));
      reader.setLineMapper(new DefaultLineMapper<User>() {
         {
            setLineTokenizer(new DelimitedLineTokenizer() {
               {
                  setNames(new String[] { "firstName", "lastName" });
               }
            });
            setFieldSetMapper(new BeanWrapperFieldSetMapper<User>() {
               {
                  setTargetType(User.class);
               }
            });
         }
      });
      return reader;
   }
   @Bean
   public UserItemProcessor processor() {
      return new UserItemProcessor();
   }
   @Bean
   public JdbcBatchItemWriter