oracle CLOB字段转换位VARCHAR
1.实际上处理CLOB字段的时候，直接TO_CHAR，当长度超过4000的时候，会报错，提示列被截取；
CLOB转varchar2：select to_char(CLOB字段) from table
2.直接使用SUBSTR对CLOB字段进行截取，是不能起到任何作用的；
3.可以使用dbms_lob.substr(clobcolumn,4000)，对CLOB字段进行截取；截取的长度是4000还是2000根据存储的是汉字和数据决定长度；
java获取oracle中CLOB字段，转换成String
try {
PreparedStatement stmt = session.connection().prepareStatement(sql);
ResultSet rs = stmt.executeQuery();
while (rs.next())
{
Clob clob = (Clob)rs.getObject(1);
result = ClobToString(clob);
}
} catch (HibernateException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
session.close();
}
//oracle.sql.Clob类型转换成String类型
public String ClobToString(Clob clob) throws SQLException, IOException {
String reString = "";
Reader is = clob.getCharacterStream();// 得到流
BufferedReader br = new BufferedReader(is);
String s = br.readLine();
StringBuffer sb = new StringBuffer();
while (s != null) {// 执行循环将字符串全部取出付值给StringBuffer由StringBuffer转成STRING
sb.append(s);
s = br.readLine();
}
reString = sb.toString();
return reString;
}