Java 使用Odata服务的SAP UI5应用程序：对象不是声明类的实例

我已经创建了一个odata服务 当我访问上面的URL时，它会正确地显示实体集

<service xmlns="<LINK>2007/app" xmlns:atom="<LINK>2005/Atom" xml:base="<SAME URL AS ABOVE>carandodatabaseodata/emplist.svc/">
  <workspace>
    <atom:title>Default</atom:title>
    <collection href="ZaeScaleprinters">
        <atom:title>ZaeScaleprinters</atom:title>
    </collection>
  </workspace>
</service>

实体类：

package model;

import java.io.Serializable;
import javax.persistence.*;


/**
 * The persistent class for the ZAE_SCALEPRINTER database table.
 * 
 */
@Entity
@Table(name="ZAE_SCALEPRINTER")
public class ZaeScaleprinter implements Serializable {
    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private ZaeScaleprinterPK id;

    public ZaeScaleprinter() {

    }

    public ZaeScaleprinterPK getId() {
        return this.id;
    }

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

}

package model;

import java.io.Serializable;
import javax.persistence.*;

/**
 * The primary key class for the ZAE_SCALEPRINTER database table.
 * 
 */
@Embeddable
public class ZaeScaleprinterPK implements Serializable {
    //default serial version id, required for serializable classes.
    private static final long serialVersionUID = 1L;

    @Column(unique=true, nullable=false, length=12)
    private String werks;

    @Column(unique=true, nullable=false, length=60)
    private String scale;

    @Column(unique=true, nullable=false, length=120)
    private String printer;

    public ZaeScaleprinterPK() {
    }
    public String getWerks() {
        return this.werks;
    }
    public void setWerks(String werks) {
        this.werks = werks;
    }
    public String getScale() {
        return this.scale;
    }
    public void setScale(String scale) {
        this.scale = scale;
    }
    public String getPrinter() {
        return this.printer;
    }
    public void setPrinter(String printer) {
        this.printer = printer;
    }

    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }
        if (!(other instanceof ZaeScaleprinterPK)) {
            return false;
        }
        ZaeScaleprinterPK castOther = (ZaeScaleprinterPK)other;
        return 
            this.werks.equals(castOther.werks)
            && this.scale.equals(castOther.scale)
            && this.printer.equals(castOther.printer);
    }

    public int hashCode() {
        final int prime = 31;
        int hash = 17;
        hash = hash * prime + this.werks.hashCode();
        hash = hash * prime + this.scale.hashCode();
        hash = hash * prime + this.printer.hashCode();

        return hash;
    }
}

---

你的类中有继承吗？我认为可能实体集中有一个派生类型的对象，而派生类型未包含/定义在Edm模型中。也许你最好能和我们分享你的元数据文档和实体集对象。我已经在上面添加了元数据信息。我没有创建任何类。我使用EclipseJuno向导构建了一个应用程序Odata-Starter应用程序Projectt的行为有所不同。现在它给了我一个错误：sun.reflect.DelegatingMethodAccessorImpl:java.lang。ClassCastException@3c4928. 现在又是先前的错误。。。！也许您应该将java添加到标记中。在我看来，这个问题不像UI5客户端问题，而是服务器端问题。

<error xmlns="<LINK>/ado/2007/08/dataservices/metadata">
    <code/>
    <message xml:lang="en">
        "sun.reflect.NativeMethodAccessorImpl: object is not an instance of declaring class. "
    </message>
</error>

package com;

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import org.apache.olingo.odata2.processor.api.jpa.ODataJPAContext;
import org.apache.olingo.odata2.processor.api.jpa.ODataJPAServiceFactory;
import org.apache.olingo.odata2.processor.api.jpa.exception.ODataJPARuntimeException;

public class ZAE_SCALEPrinterServiceFactory extends ODataJPAServiceFactory {

    private static final String PERSISTENCE_UNIT_NAME = "carandodatabaseodata";

      @Override
      public ODataJPAContext initializeODataJPAContext()
          throws ODataJPARuntimeException {

        ODataJPAContext oDatJPAContext = this.getODataJPAContext();
        try {

          EntityManagerFactory emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
    oDatJPAContext.setEntityManagerFactory(emf);
          oDatJPAContext.setPersistenceUnitName(PERSISTENCE_UNIT_NAME);

          return oDatJPAContext;

        } catch (Exception e) {

          throw new RuntimeException(e);

        }

      }

}

package model;

import java.io.Serializable;
import javax.persistence.*;


/**
 * The persistent class for the ZAE_SCALEPRINTER database table.
 * 
 */
@Entity
@Table(name="ZAE_SCALEPRINTER")
public class ZaeScaleprinter implements Serializable {
    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private ZaeScaleprinterPK id;

    public ZaeScaleprinter() {

    }

    public ZaeScaleprinterPK getId() {
        return this.id;
    }

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

}

package model;

import java.io.Serializable;
import javax.persistence.*;

/**
 * The primary key class for the ZAE_SCALEPRINTER database table.
 * 
 */
@Embeddable
public class ZaeScaleprinterPK implements Serializable {
    //default serial version id, required for serializable classes.
    private static final long serialVersionUID = 1L;

    @Column(unique=true, nullable=false, length=12)
    private String werks;

    @Column(unique=true, nullable=false, length=60)
    private String scale;

    @Column(unique=true, nullable=false, length=120)
    private String printer;

    public ZaeScaleprinterPK() {
    }
    public String getWerks() {
        return this.werks;
    }
    public void setWerks(String werks) {
        this.werks = werks;
    }
    public String getScale() {
        return this.scale;
    }
    public void setScale(String scale) {
        this.scale = scale;
    }
    public String getPrinter() {
        return this.printer;
    }
    public void setPrinter(String printer) {
        this.printer = printer;
    }

    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }
        if (!(other instanceof ZaeScaleprinterPK)) {
            return false;
        }
        ZaeScaleprinterPK castOther = (ZaeScaleprinterPK)other;
        return 
            this.werks.equals(castOther.werks)
            && this.scale.equals(castOther.scale)
            && this.printer.equals(castOther.printer);
    }

    public int hashCode() {
        final int prime = 31;
        int hash = 17;
        hash = hash * prime + this.werks.hashCode();
        hash = hash * prime + this.scale.hashCode();
        hash = hash * prime + this.printer.hashCode();

        return hash;
    }
}