Java:如何保持三个对象之间的关系

Question

我希望存储三个对象之间的关系列表，其中两个相关对象将各自仅存在于列表中的一个关系中，第三个是我可以递增的计数。它不是很普遍的 SO，但你可以在这里看到我在做什么

    public class Transaction implements AutoCloseable {
    private final Connection conn;
    private final Map<String, Map.Entry<PreparedStatement, Integer>> sts = new HashMap<>();

    Transaction(final Connection conn) throws SQLException {
        conn.setAutoCommit(false);
        this.conn = conn;
    }

    <T> void batch(final String st, final List<T> ts,
            final BatchingInstructions<T> bi) throws SQLException {
        final PreparedStatement stat;
        int counter;

        // if statement has already been created, retrieve statement and batch count
        if (sts.containsKey(st)) {
            final Map.Entry<PreparedStatement, Integer> m = sts.get(st);
            stat = m.getKey();
            counter = m.getValue();
        } else {
            // else create statement and batch count
            stat = conn.prepareStatement(getInsert(st));
            counter = 0;
            sts.put(st, // Can't do a new Map.Entry, really
        }

        for (final T t : ts) {
            bi.batch(stat, t);
            stat.addBatch();
            // increment how many times a batch has been added to the statement.
            // execute batch if necessary.
            if (++counter > 5000) {
                stat.executeBatch();
            }
        }

    }

    @Override
    public void close() throws Exception {
        for (final Map.Entry<PreparedStatement, Integer> m : sts.values()) {
            if (m.getValue() > 0) {
                m.getKey().executeBatch();
            }
            m.getKey().close();
        }
        conn.commit();
    }

Guava 的表不能正常工作，并且 Map<String, Map<Statement, Integer>>也不是理想的，并且由于需要增加其中一个值而变得复杂(尽管为此我可能会使用此处找到的 mutableInt 解决方案 Most efficient way to increment a Map value in Java )。

我想知道是否有人知道这个问题的任何直接解决方案，可能在第三方库中？

---

使用已接受的答案，我能够让新类(class)做许多其他有用的事情。

class BatchPreparedStatement implements AutoCloseable {
    private final PreparedStatement st;
    private int counter = 0;

    BatchPreparedStatement(final PreparedStatement st) {
        this.st = st;
    }

    <T> void addBatch(final BatchingInstructions<T> bi, final T t)
            throws SQLException {
        bi.batch(st, t);
        st.addBatch();
        executeBatch(10000);
    }

    void executeBatch(final int count) throws SQLException {
        if (counter++ > count) {
            st.executeBatch();
            counter = 0;
        }
    }

    void finished() throws SQLException {
        executeBatch(0);
    }

    @Override
    public void close() throws Exception {
        st.close();
    }
}

Answer 1

你为什么不创建一个类来保存语句、计数和处理所有 addBatching 以及其他杂项 Activity 。

class BatchPreparedStatementHolder {

    private int batchCount;
    private PreparedStatement ps;

    public BatchPreparedStatementHolder(PreparedStatement statement){
        batchCount = 0;
        ps = statment;
    }

    public void addBatch(){
        ps.addBatch();
        // increment how many times a batch has been added to the statement.
        // execute batch if necessary.
        if (++batchCount> 5000) {
            ps.executeBatch();
            batchCount = 0;
        }
    }

    ....

}