java - 为用户定义的 Oracle 表类型编写 MyBatis3 TypeHandler

Question

我在编写 TypeHandler 将 Oracle 用户定义的表类型转换为 Java 对象列表时遇到困难。

数据库类型和函数规范定义如下:

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;

我有一个 MyBatis 映射器，其中包含以下调用:

<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>

最后，我尝试编写一个 TypeHandler，但在 getResult 重写中惨败:

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;
    }
}

我似乎无法从传递到 TypeHandler 的 CallableStatement 到我想要的列表。

Answer 1

这是我为使其发挥作用所做的工作。

TypeHandler 需要创建一个引用单个 Oracle 类型(而不是表类型)的类型映射:

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;
    }
}

然后，DTO 类本身需要实现 ORAData 和 ORADataFactory 将所有内容粘合在一起:

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;
    }
}

当然，您需要进行适当的空值和数据检查等。