是否可以使用JDBC获取FK的目标？

我只使用getExportedKeys方法获得了源关系属性：

ResultSet fksE = dbm.getExportedKeys(conn.getCatalog(),null,"SourceRelName");
String fkTableNameE = fksE.getString("FKTABLE_NAME");
String fkColumnNameE = fksE.getString("FKCOLUMN_NAME");

然后我尝试使用getImportedKeys方法,但它没有用.

这是我的班级：

public class DbConnection {

  private String userName = null;
  private String password = null;
  private String driver = null;
  private String DbUrl = null;
  private Connection conn = null;
  private DatabaseMetaData dbm = null;
  private ArrayListMysqL:
        driver = "com.MysqL.jdbc.Driver";
        break;
      case POSTGRES:
        break;
      case MSDB:
        break;
      case ORACLE:
        break;
      case sqlITE:
        break;
    }
    DbUrl = url;
    database = new Database();
    relationNames = new ArrayList<>();

    try {
      Class.forName(driver).newInstance();
      conn = DriverManager.getConnection(DbUrl,userName,password);
      System.out.println("Database connection established");

      //Get Relation Names
      dbm = conn.getMetaData();
      String[] types = {"TABLE"};
      tables = dbm.getTables(null,"%",types);
      while (tables.next()) {
        String table = tables.getString("TABLE_NAME");
        relationNames.add(table);
      }

      //Get Attributes
      for (String relation : relationNames) {
        RelationSchema tmpRelation = new RelationSchema(relation);

        Statement st = conn.createStatement();
        ResultSet rs = st.executeQuery("SELECT * FROM " + relation);
        ResultSetMetaData md = rs.getMetaData();
        int col = md.getColumnCount();
        System.out.println("ATTRIBUTES: ");
        for (int i = 1; i <= col; i++) {
          String col_name = md.getColumnName(i);
          System.out.println(col_name);
          tmpRelation.addAttribute(col_name);
        }
        ResultSet pks = dbm.getPrimaryKeys(null,relation);
        while (pks.next()) {
          String columnName = pks.getString("COLUMN_NAME");
          System.out.println("Primary Key: " + columnName);
          tmpRelation.getAttributeByName(columnName).setIsPrimaryKey(true);
        }
        database.addRelationSchema(tmpRelation);
      }

      //Get Foreignkeys
      for (String relation : relationNames) {
        ResultSet fksE = dbm.getExportedKeys(conn.getCatalog(),relation);

        while (fksE.next()) {
          String fkTableNameE = fksE.getString("FKTABLE_NAME");
          String fkColumnNameE = fksE.getString("FKCOLUMN_NAME");
      ResultSet fksI = dbm.getImportedKeys(conn.getCatalog(),fkTableNameE);
      String fkTableNameI = fksI.getString("FKTABLE_NAME");
      String fkColumnNameI = fksI.getString("FKCOLUMN_NAME");

      System.out.println("FKTABLE_NAME_E: " + fkTableNameE + " - FKCOLUMN_NAME_E: " + fkColumnNameE);
      System.out.println("FKTABLE_NAME_I: " + fkTableNameI + " - FKCOLUMN_NAME_I: " + fkColumnNameI);
    }
  }

} catch (Exception e) {
  System.err.println("Cannot connect to database server");
  e.printStackTrace();
}
finally
{
  if (conn != null) {
    try {
      conn.close();
      System.out.println("Database connection closed");
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}


}