为用户定义的Oracle表类型编写MyBatis3 TypeHandler

Question

I am having difficulty writing a TypeHandler to convert an Oracle user-defined table type to a list of Java objects.

The database types and function spec are defined like this:

CREATE OR REPLACE TYPE MySchema.MY_TYPE IS OBJECT (
    first_name    VARCHAR2(50),
    last_name     VARCHAR2(50)
);

CREATE OR REPLACE TYPE MySchema.MY_TYPE_TBL IS TABLE OF MY_TYPE;

FUNCTION GET_MY_STUFF(my_user_name IN VARCHAR2) RETURN MySchema.MY_TYPE_TABLE;

I have a MyBatis mapper that has the following call in it:

<resultMap id="myResultMap" type="GetMyStuffResult" />
<select id="getMyStuff" statementType="CALLABLE" parameterType="map">
    {#{return_value, mode=OUT,
                     typeHandler=MyStuffToList
                     jdbcTypeName=MySchema.MY_TYPE_TABLE,
                     jdbcType=ARRAY} = 
         call MySchema.MyPackage.GET_MY_STUFF (
              my_user_name => #{userName, mode=IN, jdbcType=VARCHAR}
     )}
</select>

Finally, I am attempting to write a TypeHandler, but am failing miserably in the getResult override:

public class MyStuffToList implements TypeHandler<List<GetMyStuffResult>> {

    // Other Overrides Here

    @Override
    public List<GetMyStuffResult> getResult(CallableStatement cs, int columnIndex) 
    throws SQLException {
        List<GetMyStuffResult> results = new ArrayList<GetMyStuffResult>();
        Array array = cs.getArray(columnIndex);

        // HOW DO I CONVERT THE Array TO List<GetMyStuffResult> ???

        return results;
    }
}

I cannot seem to get from the CallableStatement passed into the TypeHandler to the list that I want.

Answer 1

Here is what I did to get this to work.

The TypeHandler needs to create a typemap that references the single Oracle type (not the table type):

public class MyStuffToList implements TypeHandler<List<GetMyStuffResult>> {

    // Other Overrides Here

    @Override
    public List<GetMyStuffResult> getResult(CallableStatement cs, int columnIndex) 
    throws SQLException {
        List<GetMyStuffResult> results = new ArrayList<GetMyStuffResult>();
        Array array = cs.getArray(columnIndex);

        // Add a TypeMap to map the Oracle object to a Java class
        Map<String, Class<?>> typeMap = new HashMap<String, Class<?>>();
        typeMap.put("MySchema.MY_TYPE", GetMyStuffResult.class);

        // Get an array of Java objects using that type map
        Object[] javaObjects = (Object[]) array.getArray(typeMap);

        // add each of these converted objects to the results list
        for (Object javaObject : javaObjects) {
            results.add((GetMyStuffResult) javaObject);
        }

        return results;
    }
}

Then, the DTO class itself needs to implement ORAData and ORADataFactory to glue everything together:

public class GetMyStuffResult implements ORAData, ORADataFactory {

    string first_name;
    string last_name;

    // Assume appropriate getters and setters for all properties here
    // public String getFirstName() {
    //      |
    //      |

    // Implement ORAData and ORADataFactory
    public ORAData create(Datum datum, int sqlType throws SQLException {
       GetMyStuffResult result = new GetMyStuffResult();

       Struct javaStruct = (Struct) datum;
       Object[] attributes = javaStruct.getAttributes();
       // ORDER MATTERS HERE - must be in order defined in Oracle
       result.setFirstName(attributes[0].toString());
       result.setLastName(attributes[1].toString());
    }

    public Datum toDatum(Connection conn) throws SQLException {
        return null;
    }
}

Of course, you'll want to do proper null and data checks, etc.