使用JPA将对象列表作为单列JSON存储的教程

public class Sensors {
    private String amplitudos;
    private Double displacement;
    private String frequencies;
    private Integer sensorId;

    public Sensors() {
    }

    public Sensors(String amplitudos, Double displacement, String frequencies, Integer sensorId) {
        this.amplitudos = amplitudos;
        this.displacement = displacement;
        this.frequencies = frequencies;
        this.sensorId = sensorId;
    }

    // Getters and Setters
    public String getAmplitudos() {
        return amplitudos;
    }

    public void setAmplitudos(String amplitudos) {
        this.amplitudos = amplitudos;
    }

    public Double getDisplacement() {
        return displacement;
    }

    public void setDisplacement(Double displacement) {
        return displacement;
    }

    public String getFrequencies() {
        return frequencies;
    }

    public void setFrequencies(String frequencies) {
        this.frequencies = frequencies;
    }

    public Integer getSensorId() {
        return sensorId;
    }

    public void setSensorId(Integer sensorId) {
        this.sensorId = sensorId;
    }
}

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import jakarta.persistence.AttributeConverter;
import jakarta.persistence.Converter;

import java.io.IOException;
import java.util.List;
import java.util.Collections; // 导入 Collections

@Converter
public class SensorsConverter implements AttributeConverter<List<Sensors>, String> {

    private final ObjectMapper objectMapper = new ObjectMapper();

    /**
     * 将实体属性（List<Sensors>）转换为数据库列类型（String JSON）
     * @param sensors 要转换的Sensors列表
     * @return 转换后的JSON字符串
     */
    @Override
    public String convertToDatabaseColumn(List<Sensors> sensors) {
        if (sensors == null) {
            return null;
        }
        try {
            return objectMapper.writeValueAsString(sensors);
        } catch (JsonProcessingException e) {
            // 生产环境中应记录日志并抛出更具体的运行时异常
            throw new IllegalArgumentException("Error converting List<Sensors> to JSON string", e);
        }
    }

    /**
     * 将数据库列类型（String JSON）转换为实体属性（List<Sensors>）
     * @param sensorsJSON 数据库中的JSON字符串
     * @return 转换后的Sensors列表
     */
    @Override
    public List<Sensors> convertToEntityAttribute(String sensorsJSON) {
        if (sensorsJSON == null || sensorsJSON.trim().isEmpty()) {
            return Collections.emptyList(); // 返回空列表而不是null
        }
        try {
            return objectMapper.readValue(sensorsJSON, new TypeReference<List<Sensors>>() {});
        } catch (IOException e) {
            // 生产环境中应记录日志并抛出更具体的运行时异常
            throw new IllegalArgumentException("Error converting JSON string to List<Sensors>", e);
        }
    }
}

import jakarta.persistence.*;
import java.io.Serializable;
import java.sql.Timestamp;
import java.util.List; // 使用 List 代替数组

@Entity
@Table(name = "SENSOR")
public class Sensor implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @Column(name = "TIMERECEIVED")
    private Timestamp timereceived;

    // 使用 @Convert 注解指定自定义转换器
    // 数据库列类型为 VARCHAR2/CLOB，Java实体属性类型为 List<Sensors>
    @Column(name = "SENSORS", columnDefinition = "CLOB") // 或 VARCHAR2(4000) 根据实际JSON大小调整
    @Convert(converter = SensorsConverter.class)
    private List<Sensors> sensors; // 类型改为 List

    @Column(name = "LOC")
    private String location;

    public Sensor() {
    }

    public Sensor(Timestamp timereceived, List<Sensors> sensors, String location) {
        this.timereceived = timereceived;
        this.sensors = sensors;
        this.location = location;
    }

    // Getters and Setters
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public Timestamp getTimereceived() {
        return timereceived;
    }

    public void setTimereceived(Timestamp timereceived) {
        this.timereceived = timereceived;
    }

    public List<Sensors> getSensors() { // 返回类型也改为 List
        return sensors;
    }

    public void setSensors(List<Sensors> sensors) { // 参数类型也改为 List
        this.sensors = sensors;
    }

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }
}

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class SensorController {

    private final SensorRepository sensorRepository; // 假设有一个 SensorRepository

    public SensorController(SensorRepository sensorRepository) {
        this.sensorRepository = sensorRepository;
    }

    @PostMapping("/sendData")
    public ResponseEntity<String> sendData(@RequestBody Sensor sensor) {
        Sensor newSensor = sensorRepository.save(sensor);
        System.out.println("Saved Sensor: " + newSensor.getId());
        // 可以打印出 newSensor.getSensors() 来验证是否正确反序列化
        System.out.println("Sensors data: " + newSensor.getSensors());
        return ResponseEntity.ok("Sensor received and saved successfully");
    }
}

{
    "timereceived": "2022-11-29T12:04:42.166",
    "sensors": [
        {
            "amplitudos": "a1#a2#a3#a4",
            "displacement": 0.002,
            "frequencies": "f1#f2#f3#f4",
            "sensorid": 1
        },
        {
            "amplitudos": "a1#a2#a3#a4",
            "displacement": 0.002,
            "frequencies": "f1#f2#f3#f4",
            "sensorid": 2
        }
    ],
    "location": "lokasi"
}