解析jdbc處理oracle的clob字段的詳解

public class ClobUtil {

 /**
  *
  * @param insertSQL 插入sql語句 有clob字段時，值必須設置成empty_clob()函數(shù) 例:insert into ba valus(1,empty_clob())
  * @param updateSQL 帶有修改的查詢語句,并應增加條件判斷.例：select * from BA where ba_id = '"+ba.getBA_id()+"' for update
  * @param con 數(shù)據(jù)庫鏈接
  * @param bigString 要插入的clob值
  * @param updateColumn 要插入的表字段名
  * @return
  * @throws SQLException
  */
 public static Boolean clobInsert(String insertSQL,String updateSQL,Connection con,String bigString,String updateColumn ) throws SQLException{
      // 結果集
      ResultSet rs = null;
      // 插入數(shù)據(jù)庫的sql
      String query = insertSQL;
      // 設置不自動提交
      con.setAutoCommit(false);
      // 定義預處理
      java.sql.PreparedStatement pstmt = con.prepareStatement( query);
      // 執(zhí)行插入語句
      pstmt.executeUpdate();
      //清空
      pstmt = null;
      // 執(zhí)行更改
      query = updateSQL;
         //顯示執(zhí)行帶有修改方式的select
      pstmt = con.prepareStatement(query);
      rs = pstmt.executeQuery();
      // 采用流的方式處理結果集
      if(rs.next()) 
      {
        // 得到指定的clob字段
        oracle.sql.CLOB singnaturedateClob = (oracle.sql.CLOB)rs.getClob(updateColumn); 
        // 把clob字段放到輸出流當中
        BufferedOutputStream out = new BufferedOutputStream(singnaturedateClob.getAsciiOutputStream());
        // 判斷傳入的數(shù)據(jù)是否為空
        if(bigString!=null){
        try{
         // 把要保存的數(shù)據(jù)轉換成輸入流
         InputStream  is = (InputStream)(new   ByteArrayInputStream(bigString.getBytes())); 
      copyStream( is, out );
      out.close();
    } catch (IOException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
        }
      }
      rs.close();
      con.commit();

   return true;
 }

 /**
  * 將輸入流寫入到輸出流當中
  * @param is 輸入流
  * @param os 輸出流
  * @throws IOException
  */
 public static void copyStream( InputStream is, OutputStream os )
 throws IOException
 {
  byte[] data             = new byte[4096];
  int readed              = is.read(data);
  while (readed != -1)
  {
   os.write(data,0,readed);
   readed = is.read(data);
  }
 }

 /**
  * 通過Clob對象返回字符串
  * @param c
  * @return
  */
 public static String getClobString(Clob c) { 
        try {

            Reader reader=c.getCharacterStream();
            if (reader == null) {
                return null;
            }
            StringBuffer sb = new StringBuffer();
            char[] charbuf = new char[4096];
            for (int i = reader.read(charbuf); i > 0; i = reader.read(charbuf)) {
                sb.append(charbuf, 0, i);
            }
            return sb.toString();
        } catch (Exception e) {
            return "";
        }
    }

}