java - setAutoCommit(true) 是否提交过去的执行？

Question

public void batchUpdate() throws SQLException {

Statement stmt = null;
try {
    this.connection.setAutoCommit(false);
    stmt = this.connection.createStatement();


    stmt.addBatch("INSERT INTO COFFEES VALUES('Amaretto_decaf', 49, 10.99, 0, 0)");

    stmt.addBatch("INSERT INTO COFFEES " +"VALUES('Hazelnut_decaf', 49, 10.99, 0, 0)");

    int [] updateCounts = stmt.executeBatch();
    this.connection.commit();

} catch(BatchUpdateException b) {
    JDBCTutorialUtilities.printBatchUpdateException(b);
} catch(SQLException ex) {
    JDBCTutorialUtilities.printSQLException(ex);
} finally {
    if (stmt != null) { stmt.close(); }
    this.connection.setAutoCommit(true);
}
}

问题:

1. 将调用 connection.setAutoCommit(true) 再次提交已经提交的语句(通过方法 connection.commit())还是仅恢复您不必调用的默认状态方法自己提交？

2. 在不调用 connection.setAutoCommit(true) 的情况下关闭连接是否会自动调用该方法，或者下次它仍然是 connection.setAutoCommit(false)打开了吗？

Answer 1

1. 已提交的语句不再提交。

2. 这取决于您的连接源:连接池可能会在该状态下释放时为您提供 autoCommit=false 连接，新连接将以默认值打开。

   It is strongly recommended that an application explicitly commits or rolls back an active transaction prior to calling the close method. If the close method is called and there is an active transaction, the results are implementation-defined. http://docs.oracle.com/javase/7/docs/api/java/sql/Connection.html#close%28%29