Spring Boot中动态读取并持久化外部JSON文件数据教程

app.data.json-file-path=/path/to/your/external/file.json
# 例如，在Linux上可能是 /opt/myapp/data/file.json
# 在Windows上可能是 C:/myapp/data/file.json

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.example.demo.model.Master;
import com.example.demo.Services.MasterService;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;

@Component // 确保这个类被Spring扫描并管理
public class JsonFileProcessor {

    private final MasterService masterService;
    private final String jsonFilePath; // 外部JSON文件的路径

    // 推荐使用构造器注入，而不是字段注入
    public JsonFileProcessor(MasterService masterService, 
                             @Value("${app.data.json-file-path}") String jsonFilePath) {
        this.masterService = masterService;
        this.jsonFilePath = jsonFilePath;
    }

    @Scheduled(fixedRate = 90000) // 每90秒执行一次
    public void readAndUpdateDatabase() {
        ObjectMapper mapper = new ObjectMapper();
        TypeReference<List<Master>> typeReference = new TypeReference<List<Master>>(){};

        try {
            // 使用Java NIO读取外部文件
            Path path = Paths.get(jsonFilePath);
            // 检查文件是否存在且可读
            if (!Files.exists(path) || !Files.isReadable(path)) {
                System.err.println("Error: JSON file not found or not readable at " + jsonFilePath);
                return;
            }

            // 读取文件所有字节并反序列化
            List<Master> masters = mapper.readValue(Files.readAllBytes(path), typeReference);
            System.out.println("Read " + masters.size() + " records from " + jsonFilePath);

            // 将读取到的数据保存到数据库
            masterService.saveAll(masters); // 假设MasterService有一个saveAll方法
            System.out.println("Saved " + masters.size() + " records to database.");

        } catch (IOException e) {
            System.err.println("Unable to read or save masters from " + jsonFilePath + ": " + e.getMessage());
            e.printStackTrace();
        }
    }
}

package com.example.demo.Services;

import com.example.demo.Repository.MasterRepository;
import com.example.demo.model.Master;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class MasterService {
    private final MasterRepository masterRepository; // 使用final关键字

    // 构造器注入
    public MasterService(MasterRepository masterRepository) {
        this.masterRepository = masterRepository;
    }

    public Iterable<Master> list() {
        return masterRepository.findAll();
    }

    public Master save(Master master){
        return masterRepository.save(master);
    }

    // 推荐添加一个saveAll方法来批量保存
    public Iterable<Master> saveAll(List<Master> masters) {
        return masterRepository.saveAll(masters);
    }
}

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@SpringBootApplication
@EnableScheduling // 启用定时任务调度
@EnableTransactionManagement // 启用事务管理
public class ReadAndWriteJsonApplication {

    public static void main(String[] args) {
        SpringApplication.run(ReadAndWriteJsonApplication.class, args);
    }

    // 原有的readFile方法可以移除，由JsonFileProcessor类处理
    // 如果有其他初始化逻辑，可以考虑使用@PostConstruct
}

package com.example.demo.Repository;

import com.example.demo.model.Master;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface MasterRepository extends CrudRepository<Master, Long> {
    // 可以根据需要添加自定义查询方法
}