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Hibernate：如何使用@EmbeddedId作为主键保存实体

javadatabasehibernateorm
12

我想学习Hibernate基础知识，但不明白为什么在使用@EmbeddedId注释进行组合主键添加条目到表中时，我的应用程序无法正常工作：

表示PK的类：

@Embeddable
public class OHLCVKey implements Serializable{

    private static final long serialVersionUID = -3996067621138883817L;

    @Column(name="Symbol")
    protected String symbol;

    @Column(name="Currency")
    protected String currency;

    @Column(name="Datum")
    protected java.sql.Date datum;

    public OHLCVKey() {}

    public OHLCVKey(String symbol, String currency, Date datum) {
        super();
        this.symbol = symbol;
        this.currency = currency;
        this.datum = datum;
    }



    public String getSymbol() {
        return symbol;
    }

    public void setSymbol(String symbol) {
        this.symbol = symbol;
    }

    public String getCurrency() {
        return currency;
    }

    public void setCurrency(String currency) {
        this.currency = currency;
    }

    public java.sql.Date getDatum() {
        return datum;
    }

    public void setDatum(java.sql.Date endTime) {
        this.datum = endTime;
    }

    @Override
    public String toString() {
        return String.format("OHLCKey: {%s %s %s}", symbol, currency, datum);
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + (symbol == null ? 0 : symbol.hashCode());
        result = prime * result + (currency == null ? 0 : currency.hashCode());
        result = prime * result + (datum == null ? 0 : datum.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if(obj != null || !(obj instanceof OHLCVKey)) {
            OHLCVKey other = (OHLCVKey) obj;
            boolean sameSymbol = this.symbol.equals(other.symbol);
            boolean sameCurrency = this.currency.equals(other.currency);
            boolean endTime = this.datum.equals(other.datum);
            return sameSymbol && sameCurrency && endTime;
        }
        return false;
    }
}

持久化类：

@Entity
@Table(name = "ohlcv_data")
public class OHLCV implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = -742762046516249869L;

    @EmbeddedId
    protected OHLCVKey key;

    @Column(name = "Exchange")
    private String exchange;

    @Column(name = "Open")
    private double open;

    @Column(name = "High")
    private double high;

    @Column(name = "Low")
    private double low;

    @Column(name = "Close")
    private double close;

    @Column(name = "Volume")
    private long volume;

    public OHLCV() {};

    public OHLCV(OHLCVKey key) {
        super();
        this.key = key;
    }

    public OHLCV(OHLCVKey key, String exchange, double open, double high, double low, double close, long volume) {
        super();
        this.key = key;
        this.exchange = exchange;
        this.open = open;
        this.high = high;
        this.low = low;
        this.close = close;
        this.volume = volume;
    }

    public OHLCVKey getKey() {
        return key;
    }

    public void setKey(OHLCVKey key) {
        this.key = key;
    }

    public String getExchange() {
        return exchange;
    }

    public void setExchange(String exchange) {
        this.exchange = exchange;
    }

    public double getOpen() {
        return open;
    }

    public void setOpen(double open) {
        this.open = open;
    }

    public double getHigh() {
        return high;
    }

    public void setHigh(double high) {
        this.high = high;
    }

    public double getLow() {
        return low;
    }

    public void setLow(double low) {
        this.low = low;
    }

    public double getClose() {
        return close;
    }

    public void setClose(double close) {
        this.close = close;
    }

    public long getVolume() {
        return volume;
    }

    public void setVolume(long volume) {
        this.volume = volume;
    }
}

我假设在创建一个 OHLC 实例后，可以使用以下函数将其数据添加到我的数据库表中（在名为 OHLCVDataManager 的类中）：

public void addOHLCV(OHLCV ohlcv) { // line 50
    Session session = factory.openSession();
    Transaction tx = null;
    try {
        tx = session.beginTransaction();
        session.save(ohlcv); // line 55
        tx.commit();
        log.info("Added {} to database!", key.toString());
    } catch(Exception e) {
        if(tx != null) {
            tx.rollback();
        }
        e.printStackTrace();
    } finally {
        session.close();
        System.exit(2); //TODO remove, exit Spring application
    }
}

但我得到了以下PropertyAccessException/IllegalArgumentException异常，并带有堆栈跟踪：

org.hibernate.property.access.spi.PropertyAccessException: Error accessing field [protected OHLCVKey OHLCV.key] by reflection for persistent property [OHLCV#key] : OHLCV@46479254
2018-11-03 18:43:57.567  INFO 18384 --- [       Thread-9] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@7582b66f: startup date [Sat Nov 03 18:43:53 CET 2018]; root of context hierarchy
    at org.hibernate.property.access.spi.GetterFieldImpl.get(GetterFieldImpl.java:75)
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:224)
    at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4931)
    at org.hibernate.mapping.Component$StandardGenerationContextLocator.locateGenerationContext(Component.java:480)
    at org.hibernate.id.CompositeNestedGeneratedValueGenerator.generate(CompositeNestedGeneratedValueGenerator.java:93)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:123)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:709)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:701)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:696)
    at OHLCVDataManager.addOHLCV(OHLCVDataManager.java:55)
    at OHLCVDataManager.addOHLCV(OHLCVDataManager.java:70)
    at ServerApplication.main(ServerApplication.java:16)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: java.lang.IllegalArgumentException: Can not set OHLCVKey field OHLCV
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
    at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)
    at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36)
    at java.lang.reflect.Field.get(Field.java:393)
    at org.hibernate.property.access.spi.GetterFieldImpl.get(GetterFieldImpl.java:71)

编辑1：

ohlcvDataManager.addOHLCV("TEST", "USD", new java.sql.Date(2018, 1, 1), "TEST", 1, 1, 1, 1, 1);

// OHLCDataManager#addOHLCV call:    
public void addOHLCV(String symbol, String currency, java.sql.Date date, 
String exchange, double open, double high, double low, double close, long volume) {
    addOHLCV(new OHLCV(new OHLCVKey(symbol,currency, date),exchange, open, high, low, close, volume));
}

编辑2： 我已经使用Java 1.8测试了5.3.7和5.4版本的hibernate-core。

编辑2： 在我的类路径中只有一个OHLCV类和一个OHLCVKey类，我也尝试过重命名这些类。

1
Hibernate的版本是什么？ - NiVeR
在保存时，OHLCV是否一定有填充的OHLCVKey？请注意saveWithGeneratedOrRequestedId()在堆栈跟踪中调用了saveWithGeneratedId()，这表明它找不到键值。 - df778899
1
你的PK的hashCode()实现可能存在缺陷。你总是返回super.hashCode()而不是result。这可能是问题的根源。 - MicSim
@MicSim 如果我返回 ´result´，它也不起作用。 - team17
@MicSim 我在java.sql.Date中使用了完整的路径限定符，我认为如果我混合使用它，代码将无法编译。 - team17
显示剩余5条评论
5个回答
2
我认为您在使用Hibernate 5.0和5.1中映射为EmbededID的复合键时遇到了一个错误。这个问题应该在5.1.1中得到解决。 https://hibernate.atlassian.net/browse/HHH-10618 尝试更改Hibernate版本。此外，我可以看到在评论中@K.Nicholas说相同的代码对他有效。这就是为什么我更倾向于认为您正在遇到这个错误的原因。
1
我使用的是5.3.7版本，升级到5.4版本也无法解决我的问题。 - team17
1
降级到版本。

4.3.11.Final

工作过程中...

0

与其降级，我重建了我的实体以使用@IdClass

继续给出的示例，您可以删除@Embeddable和@EmbeddedId注释。然后，您应该为您的OHLCV添加以下类级别的注释：

javax.persistence.@IdClass(OHLCVKey.class)

将OHLCVKey类中的变量复制到您的OHLCV类中，并为它们每个变量添加以下注释！

@Id

然后从键类中删除列注释。 不要忘记每个类都需要相等和hashCode实现！

一个小的自定义示例：

@Entity
@Table(name = "MY_TABLE")
@IdClass(ExampleCompositeKey.class)
public class Example {
    
    @Id
    @Column(name = "COLUMN_ONE")
    private String something;
    
    @Id
    @Column(name = "COLUMN_TWO")
    private String somethingElse;
    
    @Column(name = "COLUMN_THREE")
    private String regularColumn;
    
    // GETTER's and SETTER's here...
    
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof Example)) return false;
        Example example = (Example) o;
        return Objects.equals(something, example.something)
                && Objects.equals(somethingElse, example.somethingElse)
                && Objects.equals(regularColumn, example.regularColumn);
    }

    @Override
    public int hashCode() {
        return Objects.hash(something, somethingElse, regularColumn);
    }
}


public class ExampleCompositeKey implements Serializable {

    private String something;
    private String somethingElse;

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof ExampleCompositeKey)) return false;
        ExampleCompositeKey that = (ExampleCompositeKey) o;
        return Objects.equals(something, that.something)
                && Objects.equals(somethingElse, that.somethingElse);
    }

    @Override
    public int hashCode() {
        return Objects.hash(something, somethingElse);
    }
}
0

我已经有一段时间没有接触过Hibernate了，但从错误信息来看，它似乎无法访问[protected OHLCVKey OHLCV.key]这个字段。为了缩小范围，我建议你做两件事情。首先，请尝试在这一行中删除强制类型转换：OHLCVKey key = (OHLCVKey) session.save(ohlcv); // line 55，改为session.save(ohlcv)，以排除是强制类型转换还是保存本身导致的问题。其次，虽然这没有太多意义，但请尝试将此处的访问修饰符更改为private。

 @EmbeddedId
    protected OHLCVKey key;

如果以上两种方法都无法解决问题，可以尝试使用HQL。
0
Caused by: java.lang.IllegalArgumentException: Can not set OHLCVKey field OHLCV
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
    at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)
    at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36)
    at java.lang.reflect.Field.get(Field.java:393)
    at org.hibernate.property.access.spi.GetterFieldImpl.get(GetterFieldImpl.java:71)

这段堆栈跟踪表示Hibernate正在尝试将字段值设置为某个对象，但它们的类不兼容：

protected void ensureObj(Object object) {
    if (!this.field.getDeclaringClass().isAssignableFrom(object.getClass())) {
        this.throwSetIllegalArgumentException(object);
    }
}

这意味着Hibernate从不同的类中加载了元数据，而不是从您尝试保存的对象的类中加载。请检查您的应用程序类路径中是否只有一个OHLCV类，因为您提供的示例可以正常工作。
我的类路径中只有一个OHLCV类，我也已经将我的类重命名了。只有spring-boot依赖项。 - team17
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