hiker — Fri, 27 Apr 2007 01:39:00 GMT

��d��单点�Q�用到输入输出流�?/p>

1private String getClob (CLOB clob) throws Exception
2{
3    //2�U�写�?/span>
4    /**
5    oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob(1);
6    BufferedReader in = new BufferedReader(clob.getCharacterStream());
7    StringWriter out=new StringWriter();
8    int c;
9    while((c=in.read())!=-1)
10    {
11        out.write(c);
12    }
13    String content=out.toString();
14    */
15
16    String content = "";
17
18    Reader is = clob.getCharacterStream();
19    BufferedReader br = new BufferedReader(is);
20    String s = br.readLine();
21    while (s != null)
22    {
23        content += s + "\r\n";
24        s = br.readLine();
25    }
26
27    return content;
28
29}

下面是写入CLOB

1    //the first, run
2    //ResultSet rs = null;
3    //String sSQL = "select " + ColName + " from " + tableName + " where id= '" + ID + "' for update";
4    //(oracle.sql.CLOB)rs.getClob(number);
5      private void fillClob (CLOB clob, String data) throws Exception
6      {
7        if (data == null)
8        {
9            data = "no value !";
10        }
11        if (clob != null)
12        {
13            Writer wr = clob.getCharacterOutputStream();
14            wr.write(data);
15            wr.flush();
16            wr.close();
17         }
18      }

conn.setAutoCommit(false);//取消自动提交
需要被首先执行

需要插入一条新的记录时�Q�可以像下面�q�样�Q?br>
1. 先取sequence的�?br>      strSql = "select sequence(表中column的名�?.nextval from dual";
      pstm = this.conn.prepareStatement(strSql);
      rs = pstm.executeQuery();

2. 插入一个空值的CLOB
      insert into tableName t (t.CLOB_column, t.sequence) values(empty_clob(), id)
      pstm.executeUpdate();

3. 把这一行锁定，用select ...for update语句�Q�然后在写入
      strSql = "select t.CLOB_column from tableName t where t.sequence= " + id + " for update";

      pstm = this.conn.prepareStatement(strSql);
      rs = pstm.executeQuery();

      if (rs.next())
       {
            clob1= (oracle.sql.CLOB) rs.getClob(1);
             fillClob(clob1, content);
       }

      rs.close();
      conn.commit();//对应上面的那�?br>      pstm.close();

更新一条记�?br>
1. 清空CLOB的内�?br>
      strSql = "update tableName t set t.CLOB_column = empty_clob() where t.id ='" + id + "'";
      pstm = this.conn.prepareStatement(strSql);
      pstm.executeUpdate();

2. 和插入新记录一��P��需要用for update锁定

1strSql = "select t.CLOB_column from tableName t where t. ='" + id + "' for update";
2pstm = this.conn.prepareStatement(strSql);
3rs = pstm.executeQuery();
4while (rs.next())
5{
6    clob = (oracle.sql.CLOB) rs.getClob(3);
7    fillClob(clob, content);
8    conn.commit();
9}
10pstm = null;
11
12strSql = "update tableName t set t.CLOB_column, t.date = to_date('" + sdate + "','YYYY-MM-DD') where t.id = " + id;
13pstm = this.conn.prepareStatement(strSql);
14int aflag = pstm.executeUpdate();
15conn.commit();
16
17rs.close();
18pstm.close();

hiker 2007-04-27 09:39 发表评论

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