Java Hibernate：只需将@EmbeddedId作为主键保存一个实体

我想学习hibernate基础知识，但不明白为什么在使用组合主键的

@EmbeddedId

注释向表中添加条目时，我的应用程序无法工作：

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OHLC实例后，我可以使用以下函数（在名为

OHLCVDataManager

的类中）将其数据添加到数据库表中：

但我得到了以下带有堆栈跟踪的PropertyAccessException/IllegalArgumentException：

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)

EDIT1:

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));
}

EDIT2: 我已经用Java1.8测试了hibernate核心版本5.3.7和5.4

EDIT2:

---

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

我已经有一段时间没有接触hibernate了，但是从错误的角度看，它似乎无法访问

[受保护的OHLCV密钥OHLCV.key]

此字段。要缩小范围，我建议两件事。首先，查看是否可以删除此行

OHLCVKey=（OHLCVKey）session.save（ohlcv）；//第55行

并将其设置为session.save（ohlcv），以排除是铸造造成的还是保存本身。第二，尽管没有多大意义，但如果您可以将此处的访问修饰符更改为private，请尝试

 @EmbeddedId
    protected OHLCVKey key;

---

如果这两种方法中的任何一种都没有帮助，请尝试使用HQL并查看

我认为您遇到了一个组合键映射为hibernate 5.0和5.1中嵌入的bug，应该在5.1.1中修复

尝试更改hibernate版本。我还可以在其中一条评论中看到@K.Nicholas说同样的代码也适用于他。这就是为什么我更倾向于认为你正在攻击这个bug

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)

stacktrace的和平意味着Hibernate试图为某个对象设置字段值，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从不同的类加载元数据，而不是从您试图保存的对象的类加载元数据。请检查应用程序的类路径中是否只有一个OHLCV类，因为您提供的示例运行良好。

降级到版本

4.3.11.4最终版本

---

已工作…

什么是hibernate版本？在保存时，

OHLCV

是否确实有一个填充的

OHLCVKey

？请注意

saveWithGeneratedOrRequestedId（）

如何在堆栈跟踪中调用

saveWithGeneratedId（）

，这表明它找不到键值。请添加构造要保存的实例的代码。@AlanHay请参见edit1您的

hashCode（）

PK实现可能有缺陷。您总是返回

super.hashCode（）

而不是

result

。这可能是您的问题的根源。我使用了5.3.7，也更新到5.4对我不起作用。在我的类路径中只有一个OHLCV类，我还重命名了我的类。。只有spring启动依赖项。

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