EclipseLink本机查询结果导入POJO - [Class]缺少描述符

Question

我正在使用EclipseLink来运行一些Native SQL.我需要将数据返回到POJO中.我按照EclipseLink Docs上的说明进行操作,但收到错误Missing descriptor for [Class]

已命名查询列以匹配POJO的成员变量.我需要做一些额外的映射吗？

POJO:

public class AnnouncementRecipientsFlattenedDTO {

        private BigDecimal announcementId;
        private String recipientAddress;
        private String type;

        public AnnouncementRecipientsFlattenedDTO() {
            super();
        }

        public AnnouncementRecipientsFlattenedDTO(BigDecimal announcementId, String recipientAddress, String type) {
            super();
            this.announcementId = announcementId;
            this.recipientAddress = recipientAddress;
            this.type = type;
        }

    ... Getters/Setters

实体经理致电:

public List<AnnouncementRecipientsFlattenedDTO> getNormalizedRecipientsForAnnouncement(int announcementId) {
    Query query = em.createNamedQuery(AnnouncementDeliveryLog.FIND_NORMALIZED_RECIPIENTS_FOR_ANNOUNCEMENT, AnnouncementRecipientsFlattenedDTO.class);
    query.setParameter(1, announcementId);
    return query.getResultList();
}

Answer 1

我发现你可以将Native Query执行的结果放入一个包含对象的数组列表中.然后,可以遍历列表和Array元素并构建所需的Entity对象.

List<Object[]> rawResultList;

    Query query =
        em.createNamedQuery(AnnouncementDeliveryLog.FIND_NORMALIZED_RECIPIENTS_FOR_ANNOUNCEMENT);
    rawResultList = query.getResultList();

    for (Object[] resultElement : rawResultList) {
        AnnouncementDeliveryLog adl = new AnnouncementDeliveryLog(getAnnouncementById(announcementId), (String)resultElement[1], (String)resultElement[2], "TO_SEND");
        persistAnnouncementDeliveryLog(adl);
    }

Answer 2

如果映射了类,则只能对类使用本机SQL查询.您需要将AnnouncementRecipientsFlattenedDTO类定义为@Entity.

否则,只需使用SQL创建本机查询并获​​取数据数组,然后使用数据自行构建DTO.

Answer 3

老问题但可能是以下解决方案将帮助别人.

假设您要返回Oracle中给定表的列,数据类型和数据长度列表.我在下面写了一个原生样本查询:

  private static final String TABLE_COLUMNS = "select utc.COLUMN_NAME, utc.DATA_TYPE, utc.DATA_LENGTH "
        + "from user_tab_columns utc "
        + "where utc.table_name = ? "                
        + "order by utc.column_name asc";

现在要求是从上面的查询结果构造一个POJO列表.

定义TableColumn实体类如下:

@Entity
public class TableColumn implements Serializable {

@Id
@Column(name = "COLUMN_NAME")
private String columnName;
@Column(name = "DATA_TYPE")
private String dataType;
@Column(name = "DATA_LENGTH")
private int dataLength;

public String getColumnName() {
    return columnName;
}

public void setColumnName(String columnName) {
    this.columnName = columnName;
}

public String getDataType() {
    return dataType;
}

public void setDataType(String dataType) {
    this.dataType = dataType;
}

public int getDataLength() {
    return dataLength;
}

public void setDataLength(int dataLength) {
    this.dataLength = dataLength;
}

public TableColumn(String columnName, String dataType, int dataLength) {
    this.columnName = columnName;
    this.dataType = dataType;
    this.dataLength = dataLength;
}

public TableColumn(String columnName) {
    this.columnName = columnName;
}

public TableColumn() {
}

@Override
public int hashCode() {
    int hash = 0;
    hash += (columnName != null ? columnName.hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object) {

    if (!(object instanceof TableColumn)) {
        return false;
    }
    TableColumn other = (TableColumn) object;
    if ((this.columnName == null && other.columnName != null) || (this.columnName != null && !this.columnName.equals(other.columnName))) {
        return false;
    }
    return true;
}

@Override
public String toString() {
    return getColumnName();
}

}

现在我们准备构建一个POJO列表.使用下面的示例代码构建将您的结果作为POJO列表获取.

public List<TableColumn> findTableColumns(String table) {
    List<TableColumn> listTables = new ArrayList<>();
    EntityManager em = emf.createEntityManager();
    Query q = em.createNativeQuery(TABLE_COLUMNS, TableColumn.class).setParameter(1, table);
    listTables = q.getResultList();
    em.close();
    return listTables;
}

Answer 4

另外,不要忘记添加您的POJO课程persistence.xml!如果您已经习惯了IDE管理该文件,那么很容易被忽略.