JDBC读取CLOB

编程技术  /  houtizong 发布于 3年前   91

    CLOB用于存储大量的字符数据，读取CLOB的JDBC代码如下所示

import java.sql.*;import java.io.*;public class ReadClob {public static void main(String[] args) {PreparedStatement pstmt = null;ResultSet rset = null;BufferedReader reader = null;Connection conn = null;String driver = "oracle.jdbc.driver.OracleDriver";String strUrl = "jdbc:oracle:[email protected]:1521:ORCL";try {Class.forName(driver);conn = DriverManager.getConnection(strUrl, "scott", "tiger");pstmt = conn.prepareStatement("select v_clob form ord where ORD_id =?");pstmt.setInt(1, 1);rset = pstmt.executeQuery();while (rset.next()) {Clob clob = rset.getClob(1);// java.sql.Clob类型reader = new BufferedReader(new InputStreamReader(clob.getAsciiStream()));String line = null;while ((line = reader.readLine()) != null) {System.out.println(line);}}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}

    程序代码从结果集中获取CLOB字段，再将其转化为IO流进行读取。那么，JDBC将大量自读数据写入CLOB字段的操作需要首先用“for update”字句查找CLOB字段，然后从结果集中获取CLOB字段并转化为oracle.sql.CLOB类型进行写入操作。

 //写入操作String stmtString = "select v_clob form ord  where ord_id =? for update";pstmt = conn.prepareStatement(stmtString);pstmt.setInt(1, 2);rset = pstmt.executeQuery();while(rset.next()){//造型为oracle.sql.CLOBCLOB clob = (CLOB)rset.getClob(1);String newClobDate = new String("NEW CLOOB DATE");Writer writer = clob.getCharacterOutputStream();//OutStream writer = clob.getAsciiOutputStream();writer.write(newClobDate);}