Spring Boot批量服務

批處理服務是在單個任務中執行多個命令的過程。 在本章中，將學習如何在Spring Boot應用程序中創建批處理服務。

在開始學習之前，請考慮一個示例，如何將CSV文件內容保存到HSQLDB中。

要創建批處理服務程序，需要在構建配置文件中添加Spring Boot Starter Batch依賴項和HSQLDB依賴項。

Maven用戶可以在pom.xml 文件中添加以下依賴項。

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

Gradle用戶可以在build.gradle 文件中添加以下依賴項。

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

現在，在資源目錄 - src/main/resources 下添加簡單的CSV數據文件，並將文件命名爲file.csv，如圖所示 -

Max,Su
Da, Lee
Sanfeng, Zhang

接下來，爲HSQLDB編寫一個SQL腳本 - 在資源目(src/main/resources)錄下創建一個文件: 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)
);

創建一個POJO類，如圖所示 -

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;
   }   
}

現在，創建一箇中間處理器，在從CSV文件讀取數據之後和將數據寫入SQL之前執行操作。

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;
   }
}

創建一個Batch配置文件，從CSV讀取數據並寫入SQL文件，如下所示。需要在配置類文件中添加[@EnableBatchProcessing](https://github.com/EnableBatchProcessing "@EnableBatchProcessing")註釋。 [@EnableBatchProcessing](https://github.com/EnableBatchProcessing "@EnableBatchProcessing")註釋用於啓用Spring Boot應用程序的批處理操作。

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<User> writer() {
      JdbcBatchItemWriter<User> writer = new JdbcBatchItemWriter<User>();
      writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<User>());
      writer.setSql("INSERT INTO USERS (first_name, last_name) VALUES (:firstName, :lastName)");
      writer.setDataSource(dataSource);
      return writer;
   }
   @Bean
   public Job importUserJob(JobCompletionNotificationListener listener) {
      return jobBuilderFactory.get("importUserJob").incrementer(
         new RunIdIncrementer()).listener(listener).flow(step1()).end().build();
   }
   @Bean
   public Step step1() {
      return stepBuilderFactory.get("step1").<User, User>chunk(10).reader(reader()).processor(processor()).writer(writer()).build();
   }
}

reader()方法用於從CSV文件中讀取數據，而writer()方法用於將數據寫入SQL。

接下來，將編寫一個作業完成通知監聽器類 - 用於在作業完成後通知。

package com.yiibai.batchservicedemo;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

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.jdbc.core.RowMapper;
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 !! It's time to verify the results!!");

         List<User> results = jdbcTemplate.query(
            "SELECT first_name, last_name FROM USERS", new RowMapper<User>() {

            @Override
            public User mapRow(ResultSet rs, int row) throws SQLException {
               return new User(rs.getString(1), rs.getString(2));
            }
         });

         for (User person : results) {
            log.info("Found <" + person + "> in the database.");
         }
      }
   }
}

現在，創建一個可執行的JAR文件，並使用以下Maven或Gradle命令運行Spring Boot應用程序。

對於Maven，使用如下所示的命令 -

mvn clean install

在「BUILD SUCCESS」之後，在target目錄下找到JAR文件。

對於Gradle，可以使用如下所示的命令 -

gradle clean build

在「BUILD SUCCESSFUL」之後，可以在build/libs目錄下找到JAR文件。

使用此處給出的命令運行JAR文件 -

java –jar <JARFILE>

在控制檯窗口中看到作業執行過程輸出。

以下是糾正/補充內容：

應該少了數據庫在application.resources中的配置   提交時間：2019-08-29