【Java/Oracle】怎样从Clob字段读取内容

有个表是这样的：

create table emp430_1(
    id number(12),
    name nvarchar2(20),
    profile clob,
    primary key(id)
);

其中profile为clob类型，这种类型可以容纳超大文本。

以下是从中连续读取数据的程序：

package com.hy.lab.clob;

import java.io.Reader;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class ClobReader {
    //-- 以下为连接Oracle数据库的四大参数
    private static final String DRIVER = "oracle.jdbc.driver.OracleDriver";
    private static final String URL = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";
    private static final String USER = "luna";
    private static final String PSWD = "1234";

    public static void main(String[] args){
        List ls=new ArrayList<>();
        ls.add(new Emp(1,"武松","双刀客"));
        ls.add(new Emp(2,"李逵","双斧头客"));
        ls.add(new Emp(3,"董平","双枪将"));
        ls.add(new Emp(4,"鲁达","扁铲发明者"));

        Connection conn = null;
        PreparedStatement pstmt = null;

        try {
            Class.forName(DRIVER);
            conn = DriverManager.getConnection(URL, USER, PSWD);
            conn.setAutoCommit(false);

            String sql="select * from emp430_1";
            pstmt = conn.prepareStatement(sql);
            ResultSet rs=pstmt.executeQuery();

            while(rs.next()){
                long id=rs.getLong("id");
                String name=rs.getString("name");
                Clob clob=rs.getClob("profile");
                String profile=extractTxtFrom(clob);
                System.out.println(String.format("Emp id=%d name=%s profile=%s",id,name,profile));
            }

            rs.close();
            System.out.println("完成读取");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                pstmt.close();
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    private static String extractTxtFrom(Clob clob) throws Exception{
        Reader reader=clob.getCharacterStream();
        char[] arr=new char[1024];
        int length=reader.read(arr);
        StringBuilder sb=new StringBuilder();
        while(length!=-1){
            String part=new String(arr,0,length);
            sb.append(part);
            length=reader.read(arr);
        }
        return sb.toString();
    }
}

END