从存储过程返回的STRUCT中读取ARRAY

Question

在数据库中有三种Oracle自定义类型(简化)如下:

create or replace TYPE T_ENCLOSURE AS OBJECT(
  ENCLOSURE_ID      NUMBER(32,0),
  ENCLOSURE_NAME    VARCHAR2(255 BYTE),
  ANIMALS           T_ARRAY_ANIMALS,

  MEMBER FUNCTION   CHECK_IF_RED RETURN BOOLEAN
);


create or replace TYPE T_ARRAY_ANIMALS is TABLE OF T_ANIMAL;


create or replace TYPE T_ANIMAL AS OBJECT(
  ANIMAL_ID NUMBER(32,0),
  NUMBER_OF_HAIRS NUMBER(32,0)
);

和一个构建对象树的函数

FUNCTION GET_ENCLOSURE ( f_enclosure_id zoo_schema.ENCLOSURE_TABLE.ENCLOSURE_ID%TYPE ) RETURN T_ENCLOSURE
AS
    v_ENC T_ENCLOSURE;
    v_idx pls_integer;

BEGIN

    v_ENC := T_ENCLOSURE(
        f_enclosure_id,
        NULL,
        T_ARRAY_ANIMALS(T_ANIMAL(NULL,NULL))
    );

    SELECT ENCLOSURE_NAME
    INTO   v_ENC.ENCLOSURE_NAME
    FROM   ENCLOSURE_TABLE WHERE ENCLOSURE_ID = f_ENCLOSURE_ID;

    SELECT
        CAST(MULTISET(
            SELECT ANIMAL_ID, NUMBER_OF_HAIRS
            FROM   ANIMAL_TABLE
            WHERE  ENCLOSURE_ID = f_ENCLOSURE_ID
        ) AS T_ARRAY_ANIMALS
    )
    INTO v_ENC.ANIMALS
    FROM dual;

RETURN v_ENC;

END;

现在我想调用该GET_ENCLOSURE函数并T_ENCLOSURE在我的Java代码中使用其结果对象.

// prepare the call
Connection connection = MyConnectionFactory.getConnection(SOME_CONNECTION_CONFIG);
CallableStatement stmt = connection.prepareCall("{? = call zoo_schema.zoo_utils.GET_ENCLOSURE( ? )}");
stmt.registerOutParameter(1, OracleTypes.STRUCT, "zoo_schema.T_ENCLOSURE");
stmt.setInt(2, 6);  // fetch data for ENCLOSURE#6

// execute function
stmt.executeQuery();

// extract the result
Struct resultStruct = (Struct)stmt.getObject(1); // java.sql.Struct

我可以通过访问ID和NAME

Integer id = ((BigInteger)resultStruct.getAttributes()[0]).intValue(); // works for me
String name = (String)resultStruct.getAttributes()[1]); // works for me

但是,我似乎无法获得动物名单

resultStruct.getAttributes()[2].getClass().getCanonicalName(); // oracle.sql.ARRAY
ARRAY arrayAnimals = (ARRAY)jdbcStruct.getAttributes()[2];
arrayAnimals.getArray(); // throws a java.sql.SQLException("Internal Error: Unable to resolve name")

我在这里有一些试验和错误,包括

OracleConnection oracleConnection = connection.unwrap(OracleConnection.class);
STRUCT resultOracleStruct = (STRUCT) stmt.getObject(1); // oracle.sql.STRUCT
oracleConnection.createARRAY("zoo_schema.T_ARRAY_ANIMALS", resultOracleStruct.getAttributes()[2]) // throws an SQLException("Fail to convert to internal representation: oracle.sql.ARRAY@8de7cfc4")

但也没有运气.

我怎样才能把动物列表变成一个List<TAnimal>？

Answer 1

只要 Oracle 特定的解决方案就足够了，关键就在于 DTO。所有这些都必须实施ORAData并ORADataFactory

public class TAnimal implements ORAData, ORADataFactory {
    Integer animal_id, number_of_hairs;

    public TAnimal() { }

    // [ Getter and Setter omitted here ]

    @Override
    public Datum toDatum(Connection connection) throws SQLException {
        OracleConnection oracleConnection = connection.unwrap(OracleConnection.class);
        StructDescriptor structDescriptor = StructDescriptor.createDescriptor("zoo_schema.T_ANIMAL", oracleConnection);
        Object[] attributes = {
                this.animal_id,
                this.number_of_hairs
        };
        return new STRUCT(structDescriptor, oracleConnection, attributes);
    }

    @Override
    public TAnimal create(Datum datum, int sqlTypeCode) throws SQLException {
        if (datum == null) {
            return null;
        }
        Datum[] attributes = ((STRUCT) datum).getOracleAttributes();
        TAnimal result = new TAnimal();
        result.animal_id = asInteger(attributes[0]); // see TEnclosure#asInteger(Datum)
        result.number_of_hairs = asInteger(attributes[1]); // see TEnclosure#asInteger(Datum)
        return result;
    }

}

和

public class TEnclosure implements ORAData, ORADataFactory {

    Integer enclosureId;
    String enclosureName;
    List<Animal> animals;

    public TEnclosure() {
        this.animals = new ArrayList<>();
    }

    // [ Getter and Setter omitted here ]

    @Override
    public Datum toDatum(Connection connection) throws SQLException {
        OracleConnection oracleConnection = connection.unwrap(OracleConnection.class);
        StructDescriptor structDescriptor = StructDescriptor.createDescriptor("zoo_schema.T_ENCLOSURE", oracleConnection);
        Object[] attributes = {
                this.enclosureId,
                this.enclosureName,
                null // TODO: solve this; however, retrieving data works without this
        };
        return new STRUCT(structDescriptor, oracleConnection, attributes);
    }

    @Override
    public TEnclosure create(Datum datum, int sqlTypeCode) throws SQLException {
        if (datum == null) {
            return null;
        }
        Datum[] attributes = ((STRUCT) datum).getOracleAttributes();
        TEnclosure result = new TEnclosure();
        result.enclosureId = asInteger(attributes[0]);
        result.enclosureName = asString(attributes[1]);
        result.animals = asListOfAnimals(attributes[2]);
        return result;
    }

    // Utility methods

    Integer asInteger(Datum datum) throws SQLException {
        if (datum == null)
            return null;
        else
            return ((NUMBER) datum).intValue(); // oracle.sql.NUMBER
    }

    String asString(Datum datum) throws SQLException {
        if (datum = null)
            return null;
        else
            return ((CHAR) datum).getString(); // oracle.sql.CHAR
    }

    List<TAnimal> asListOfAnimals(Datum datum) throws SQLException {
        if (datum == null)
            return null;
        else {
            TAnimal factory = new TAnimal();

            List<TAnimal> result = new ArrayList<>();

            ARRAY array = (ARRAY) datum; // oracle.sql.ARRAY
            Datum[] elements = array.getOracleArray();
            for (int i = 0; i < elements.length; i++) {
                result.add(factory.create(elements[i], 0));
            }
            return result;
        }
    }
}

然后获取数据的工作方式如下：

    TEnclosure factory = new TEnclosure();

    Connection connection = null;
    OracleConnection oracleConnection = null;
    OracleCallableStatement oracleCallableStatement = null;

    try {
        connection = MyConnectionFactory.getConnection(SOME_CONNECTION_CONFIG);
        oracleConnection = connection.unwrap(OracleConnection.class);
        oracleCallableStatement = (OracleCallableStatement) oracleConnection.prepareCall("{? = call zoo_schema.zoo_utils.GET_ENCLOSURE( ? )}");

        oracleCallableStatement.registerOutParameter(1, OracleTypes.STRUCT, "zoo_schema.T_ENCLOSURE");
        oracleCallableStatement.setInt(2, 6);  // fetch data for ENCLOSURE#6

        // Execute query
        oracleCallableStatement.executeQuery();

        // Check result
        Object oraData = oracleCallableStatement.getORAData(1, factory);
        LOGGER.info("oraData is a {}", oraData.getClass().getName()); // acme.zoo.TEnclosure

    } finally {
        ResourceUtils.closeQuietly(oracleCallableStatement);
        ResourceUtils.closeQuietly(oracleConnection);
        ResourceUtils.closeQuietly(connection); // probably not necessary...
    }