上一篇文章讲到了用Sql语句取得表空间,表空间下的表,表的字段信息的方法,但是我们还有更加通用的方法,那就是用Jdbc API直接操作,请看下面三个函数.

  /**
   * 取得数据库中所有Schema
   *
   * @return
   */
  public List getTableSchemas(){
    List retval = new ArrayList();
    try {
      Connection connection = getConnection();
      DatabaseMetaData dbmd = connection.getMetaData();
      ResultSet resultSet = dbmd.getSchemas();

      while (resultSet.next()) {
        String tableName = resultSet.getString(1);
        retval.add(tableName);
      }
    } catch (SQLException e) {     
      e.printStackTrace();
    }

    return retval;
  }

  /**
   * 取得某Schema下所有表名
   *
   * @param schema
   * @return
   */
  public List getTablesInSchema(String schema){
    List retval = new ArrayList();

    try {
      Connection connection = getConnection();
      DatabaseMetaData dbmd = connection.getMetaData();
      String[] types = { "TABLE" };
      ResultSet resultSet = dbmd.getTables(null, null, "%", types);

      // Get the table names
      while (resultSet.next()) {
        // Get the table name
        String tableName = resultSet.getString(3);
        String tableSchema = resultSet.getString(2);

        if (tableSchema.equals(schema)) {
          retval.add(tableName);
        }
      }
    } catch (SQLException e) {
      e.printStackTrace();
    }

    return retval;
  }

  /**
   * 取得某表下的所有字段信息
   *
   * @param table
   * @return
   */
  public List getColumnInfoesInTable(String table){
    List retval = new ArrayList();

    try {
      Connection connection = getConnection();

      // Create a result set
      Statement stmt = connection.createStatement();
      ResultSet rs = stmt.executeQuery("SELECT * FROM " + table);

      // Get result set meta data
      ResultSetMetaData rsmd = rs.getMetaData();
      int numColumns = rsmd.getColumnCount();

      // Get the column names; column indices start from 1
      for (int i = 1; i < numColumns + 1; i++) {
        ColumnInfoBean columnInfoBean = new ColumnInfoBean();

        // 字段名
        columnInfoBean.setName(rsmd.getColumnName(i));

        // 字段类型
        columnInfoBean.setTypeName(rsmd.getColumnTypeName(i));

        // 字段类型对应的java类名
        columnInfoBean.setClassName(rsmd.getColumnClassName(i));

        // 显示的长度
        columnInfoBean.setDisplaySize(String.valueOf(rsmd
            .getColumnDisplaySize(i)));

        // Precision
        columnInfoBean.setPrecision(String
            .valueOf(rsmd.getPrecision(i)));

        // Scale
        columnInfoBean.setScale(String.valueOf(rsmd.getScale(i)));

        retval.add(columnInfoBean);
      }
    } catch (SQLException e) {
      e.printStackTrace();
    }

    return retval;
  }