如何使用jdbc中的ResultSet.getBinaryStream（）从所有列中获取值？ [英] How do you get values from all columns using ResultSet.getBinaryStream() in jdbc?

问题描述

如何使用jdbc将一个ENTIRE表写入平面文件？到目前为止，我尝试了以下内容：

How do I to write an ENTIRE table to a flat file using jdbc? So far I've attemptedthe following:

Statement statement = connection.createStatement();
   ResultSet result = statement.executeQuery("SELECT * FROM tablename");
   BufferedInputStream buffer;
   FileOutputStream out = new FileOutputStream("flatfile.txt");
   while(result.next() )
   {
      buffer =  new BufferedInputStream(result.getBinaryStream("????") );
      byte[] buf = new byte[4 * 1024]; //4K buffer
      int len;
      while( (len = buffer.read(buf, 0, buf.length) ) != -1 )
      {
          out.write(buf, 0, len );
      }
   }
   out.close();

????只是我的占位符

"????" is just my placeholder. I am stuck on what to pass in as an argument.

推荐答案

您可以从列表中获取所有的列名称和整个数据表使用下面的代码。
writeToFile方法将包含写入文件的逻辑（如果不够明确:) :)

You can get all the column names and the entire data from your table using the code below. writeToFile method will contain the logic to writing to file (if that was not obvious enough :) )

    ResultSetMetaData metadata = rs.getMetaData();
    int columnCount = metadata.getColumnCount();    
    for (int i = 1; i <= columnCount; i++) {
        writeToFile(metadata.getColumnName(i) + ", ");      
    }
    System.out.println();
    while (rs.next()) {
        String row = "";
        for (int i = 1; i <= columnCount; i++) {
            row += rs.getString(i) + ", ";          
        }
        System.out.println();
        writeToFile(row);

    }

这篇关于如何使用jdbc中的ResultSet.getBinaryStream（）从所有列中获取值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！