Hibernate：将 Double 作为 Int 保存到数据库

发布于 2024-10-15 18:44:17 字数 1020 浏览 1 评论 0原文

有谁知道我如何创建一个Java POJO，它在内存中存储一个双精度值，但在磁盘上存储一个整数？

我想将这些对象作为整数存储到磁盘，因为我有 1 亿个对象，这样可以节省空间。然而，有时我的 Java 代码会操作内存中的值（而不保存它们）并将它们转换为实数，

我尝试过类似的方法：

@Entity
@Table(name = "POJO")
public class POJO {
@Id
@GeneratedValue
@Column(name = "id")
int id;

@Column(name = "value")
int valueInteger; // this is weird:  in the database, we want to use integers, to save space.  but in memory, sometimes we use real values
double value;

public int getValueInteger() {
    return valueInteger;
}

public void setValueInteger(int valueInteger) {
    this.valueInteger = valueInteger;
    this.value = valueInteger;
}

public double getValue() {
    return value;
}

public void setValue(double value) {
    this.value = value;
    // might want to call setValueInteger() here if consistency is required.  Right now, I think it's not, so I'll leave it out.
}
}

这不是一个糟糕的解决方案，只是内存占用量大于所需的大小。有没有办法让 POJO 只有一个双精度数（当然还有 ID），并指示 hibernate 在存储到数据库时强制将双精度数转换为整数（例如，通过舍入该双精度数）？

感谢您的帮助！

原文

does anyone know how I can create a Java POJO which has stores a double in memory but an integer on disk?

I would like to store these objects to disk as integers, because I have 100 million of them, and that would save space. However, sometimes my Java code manipulates the values in memory (without saving them) and turns them into real numbers

I have tried something like:

@Entity
@Table(name = "POJO")
public class POJO {
@Id
@GeneratedValue
@Column(name = "id")
int id;

@Column(name = "value")
int valueInteger; // this is weird:  in the database, we want to use integers, to save space.  but in memory, sometimes we use real values
double value;

public int getValueInteger() {
    return valueInteger;
}

public void setValueInteger(int valueInteger) {
    this.valueInteger = valueInteger;
    this.value = valueInteger;
}

public double getValue() {
    return value;
}

public void setValue(double value) {
    this.value = value;
    // might want to call setValueInteger() here if consistency is required.  Right now, I think it's not, so I'll leave it out.
}
}

This is not a terrible solution, except the memory footprint is larger than needed. Is there some way to have the POJO have only a double (and the ID of course), and instruct hibernate to force a double to integer conversion when it stores to the database (for instance, by rounding that double)?

Thanks for the help!

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忘羡 2024-10-22 18:44:17

希望这有效：

@Column(name = "value")
private int intValue;

@Transient
private Double value = null;

public double getValue() {
     if (value == null)
         value = intValue;
     return value;
}

public void setValue(double value) {
     this.value = value;
     this.intValue = value;
}

Hope this works:

@Column(name = "value")
private int intValue;

@Transient
private Double value = null;

public double getValue() {
     if (value == null)
         value = intValue;
     return value;
}

public void setValue(double value) {
     this.value = value;
     this.intValue = value;
}

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