Spring Batch ItemReader组件-Json文件

目录

引言

案例

转视频版

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引言

接着上篇：Spring Batch ItemReader组件-读平面文件，了解Spring Batch 读取平面文件后，接下来一起学习一下Spring Batch 如何读取Json格式数据

案例

Spring Batch 也提供专门操作Json文档的API ： JsonItemReader，具体使用且看案例

需求：读取下面json格式文档

user.json

[
  {"id":1, "name":"dafei", "age":18},
  {"id":2, "name":"xiaofei", "age":17},
  {"id":3, "name":"zhongfei", "age":16},
  {"id":4, "name":"laofei", "age":15},
  {"id":5, "name":"feifei", "age":14}
]

代码

package com.langfeiyes.batch._23_itemreader_flat_json;

import com.fasterxml.jackson.databind.ObjectMapper;
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.ItemWriter;
import org.springframework.batch.item.json.JacksonJsonObjectReader;
import org.springframework.batch.item.json.JsonItemReader;
import org.springframework.batch.item.json.builder.JsonItemReaderBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;

import java.util.List;

@SpringBootApplication
@EnableBatchProcessing
public class JsonFlatReaderJob {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;


    @Bean
    public JsonItemReader<User> userItemReader(){

    	ObjectMapper objectMapper = new ObjectMapper();
    	JacksonJsonObjectReader<User> jsonObjectReader = new JacksonJsonObjectReader<>(User.class);
        jsonObjectReader.setMapper(objectMapper);

        return new JsonItemReaderBuilder<User>()
                .name("userJsonItemReader")
                .jsonObjectReader(jsonObjectReader)
                .resource(new ClassPathResource("users.json"))
            .build();
	}

    @Bean
    public ItemWriter<User> itemWriter(){
        return new ItemWriter<User>() {
            @Override
            public void write(List<? extends User> items) throws Exception {
                items.forEach(System.err::println);
            }
        };
    }

    @Bean
    public Step step(){
        return stepBuilderFactory.get("step1")
                .<User, User>chunk(1)
                .reader(userItemReader())
                .writer(itemWriter())
                .build();

    }

    @Bean
    public Job job(){
        return jobBuilderFactory.get("json-flat-reader-job")
                .start(step())
                .build();
    }
    public static void main(String[] args) {
        SpringApplication.run(JsonFlatReaderJob.class, args);
    }
}

上面代码核心在：userItemReader() 实例方法，明确指定转换成json格式需要使用转换器，本次使用的Jackson 。

到这，本篇就结束了，欲知后事如何，请听下回分解~

转视频版

看文字不过瘾可以切换视频版：Spring Batch高效批处理框架实战