如何从Java中的指定表中返回列数、列名和列类型？

Question

我的作业是打印给定输入表的列数、名称和类型。代码如下：

public void printTableInfo(String tableName) throws DLException{
        String catalog = null;
        String schemaPattern = null;
        String tableNamePattern = tableName;
        String columnNamePattern = null;
        int columnCount = 0;
        String columnName = null;
        int columnType = 0;
        String columnPrimaryKeys = null;
        try {
            DatabaseMetaData dbmd = connection.getMetaData();

            ResultSet result = dbmd.getColumns(catalog, schemaPattern, tableNamePattern, columnNamePattern);
            ResultSetMetaData rsmd = result.getMetaData();
            columnCount = rsmd.getColumnCount();
            ResultSet primaryKeys = dbmd.getPrimaryKeys(catalog, schemaPattern, tableNamePattern);

            while(result.next()) {
                columnName = result.getString(4);
                columnType = result.getInt(5);
            }
            while(primaryKeys.next()) {
                columnPrimaryKeys = primaryKeys.getString(4);
            }
            System.out.println("\nColumn count: " + columnCount + ", Column names: " + columnName + ", Column Types: " + columnType + "\nPrimary Keys: " + columnPrimaryKeys);
        } catch (SQLException sqle) {
            throw new DLException(sqle, "-> Error in processing data printing (SQLException) to the database at printTableInfo() method.");
        }
    }

但是，当我运行此代码时，它给我的表的列数比它有的多，只有最后一个列名，以及不正确的列类型数。我怎样才能使它产生正确的列数，显示所有列名和正确数量的列类型？ P.S 主键部分工作正常。

Answer 1

我想通了，我没有在正确的位置打印。告我。