4

我有以下表格 -

@DatabaseTable(tableName="b", daoClass=B_DaoImpl.class)
public class B {

   @DatabaseField
   public String b1 ;

   public B(){
     // For Ormlite
   }
}

@DatabaseTable(tableName="a", daoClass=A_DaoImpl.class)
public class A {

   @DatabaseField
   public String a1 ;

   @DatabaseField(foreign=true)
   public B b;

   public A(){
     // For Ormlite
   }
}

对于这些表，关联的 Dao 和 DaoImpl 如下

public interface A_Dao extends Dao<A, String>{}
public interface B_Dao extends Dao<B, String>{}


public class B_DaoImpl extends BaseDaoImpl<User, String> implements B_Dao {

   public B_DaoImpl(ConnectionSource connectionSource) throws SQLException {
      super(connectionSource, B.class);
   }
}

public class A_DaoImpl extends BaseDaoImpl<User, String> implements A_Dao {

   public A_DaoImpl(ConnectionSource connectionSource) throws SQLException {
      super(connectionSource, A.class);
   }
}

数据库助手如下：

 public class DatabaseHelperImpl extends OrmLiteSqliteOpenHelper implements DatabaseHelper {

   private A_DaoImpl aDao = null;
   private B_DaoImpl bDao = null;

   public B_DaoImpl getBDao() throws SQLException {
       if (bDao == null) {
          bDao = getDao(B.class);
       }
       return bDao;
   }

   public A_DaoImpl getA() throws SQLException {
        if (aDao  == null ) {
          aDao = getDao(A.class);
        }
        return aDao;
   }
}

现在，当我尝试打电话时——

ADao aDao = databaseHelper.getA();

它出现以下错误：

 Could not call the constructor in class class A_DaoImpl

现在，如果我在 A 中没有外键 - 即如果 A 不包含public B b，它可以正常工作。我在这里缺少什么吗？

非常感谢您提前。

4

1 回答 1

6

我怀疑在异常堆栈跟踪结束时缺少原因消息。例如，如果我复制上面的示例，我会得到：

java.sql.SQLException: Could not call the constructor in class class 
      com.j256.ormlite.table.CustomDaoTest$A_DaoImpl
  at com.j256.ormlite.misc.SqlExceptionUtil.create(SqlExceptionUtil.java:22)
  ...
Caused by: java.lang.reflect.InvocationTargetException
  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  ...
Caused by: java.lang.IllegalArgumentException: Foreign field class
>>>>      com.j256.ormlite.table.CustomDaoTest$B does not have id field  <<<<<<
  at com.j256.ormlite.field.FieldType.configDaoInformation(FieldType.java:332)
  ...

因为A有class的外部字段B，所以B需要有一个id字段。外部字段需要标识字段。

我确定A并且B是您的课程的简单版本，因此如果您发布更多异常，包括所有原因信息，我将适当地编辑我的答案。

于 2012-04-17T02:37:23.993 回答