public class ClobUtil {/**
*
* @param insertsql 插入sql语句 有clob字段时，值必须设置成empty_clob()函数 例:insert into ba valus(1,empty_clob())
* @param updatesql 带有修改的查询语句,并应增加条件判断.例：select * from BA where ba_id = '"+ba.getBA_id()+"' for update
* @param con 数据库链接
* @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{
// 结果集
ResultSet rs = null;
// 插入数据库的sql
String query = insertsql;
// 设置不自动提交
con.setAutoCommit(false);
// 定义预处理
java.sql.PreparedStatement pstmt = con.prepareStatement( query);
// 执行插入语句
pstmt.executeUpdate();
//清空
pstmt = null;
// 执行更改
query = updatesql;
//显示执行带有修改方式的select
pstmt = con.prepareStatement(query);
rs = pstmt.executeQuery();
// 采用流的方式处理结果集
if(rs.next())
{
// 得到指定的clob字段
oracle.sql.CLOB singnaturedateClob = (oracle.sql.CLOB)rs.getClob(updateColumn);
// 把clob字段放到输出流当中
BufferedOutputStream out = new BufferedOutputStream(singnaturedateClob.getAsciIoUtputStream());
// 判断传入的数据是否为空
if(bigString!=null){
try{
// 把要保存的数据转换成输入流
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;
}

/**
* 将输入流写入到输出流当中
* @param is 输入流
* @param os 输出流
* @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,readed);
readed = is.read(data);
}
}/**
* 通过Clob对象返回字符串
* @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,i);
}
return sb.toString();
} catch (Exception e) {
return "";
}
}

}