How to programmatically create a Java ResultSet from custom data with no database

Question

I have some existing code that accepts a java.sql.ResultSet that contains info retrieved from an Oracle database. I would now like to reuse this code, but I\'d

Answer 1

• Create your own AbstractResultSet class, one that (like AbstractQueue) implements all methods by throwing UnsupportedOperationException (Eclipse autogenerates these methods in a split second).
• Now extend AbstractResultSet. The subclass can override only the methods you're interested in implementing.

Answer 2

I don't normally answer java questions, as I'm not a java developer, but this seems like an architectural flaw if you need to create a sql object from code to pass into a method in order to recycle a method. I would think you would want to make your receiving method accept some other more specific form of input (such as a custom defined object array) to make it reusable, and then parse your ResultData into that format.

Answer 3

You could take a look at the CachedRowSet interface:

http://java.sun.com/j2se/1.5.0/docs/api/javax/sql/rowset/CachedRowSet.html

which allows you work in disconnected mode.

Answer 4

java.sql.ResultSet is an interface, so you could create your own class that implements that interface.

Answer 5

jOOQ has a MockResultSet for that and similar purpose, which can be used out of the box, or copied into your project.

DSLContext ctx = DSL.using(DEFAULT);
Field<Integer> col1 = DSL.field("COL1", SQLDataType.INTEGER);
Field<String> col2 = DSL.field("COL2", SQLDataType.VARCHAR(10));

Result<?> result = ctx.newResult(col1, col2);
result.add(ctx.newRecord(col1, col2).values(1, "a"));
result.add(ctx.newRecord(col1, col2).values(2, "b"));

try (ResultSet rs = new MockResultSet(result)) {
    while (rs.next())
        System.out.println(rs.getInt(1) + ": " + rs.getString(2));
}

Disclaimer: I work for the company behind jOOQ.

Answer 6

This is a slightly left-field solution, but you could make use of a mocking framework (e.g. JMock). These frameworks are generally intended for creating mock implementations of interfaces for unit testing, but I see no reason why you could use one to create a "partial implementation" of java.sql.ResultSet.

For example, say you only wanted to implement the getString() method, and nothing else:

Mockery mockery = new Mockery();
final ResultSet resultSet = mockery.mock(ResultSet.class);

mockery.checking(new Expectations() {{
    allowing(resultSet).getString(1); will(returnValue("my first string"));
    allowing(resultSet).getString(2); will(returnValue("my second string"));
}});

// resultSet is now a java.sql.ResultSet object, which you can pass to your legacy code
resultSet.getString(1);

Rather unorthodox, and quite cumbersome, but it should work