因为String 类型能够接收的字节数相当有限，所以
一旦文本或者图象较大则是无法全部存与数据库中
相应的从数据库取出来也是不完全的了

本程序修正了上面的程序，热烈推荐大家看我在上遍文章参考的那本书！

import java.io.*;
import java.sql.*;

public class Db {
public static void main(String[] args) {

Db ac = new Db();

String blobname = "D: est1.jpg"; //blob文件名

String in = "insert into ";

String in1 = "(id,data) values(´0012´,?)";

String tablename = "Ss";

String sqlstr = ""; // sql 语句
sqlstr = in + tablename + in1;

ThreadUseExtends thread = new ThreadUseExtends(blobname,sqlstr);
thread.insert();
thread.getCover();

}
}

class ThreadUseExtends {
String filename1;//blob filename


String str;
//ReadFiles r1 = new ReadFiles();

//构造函数要有（blob文件名,clob文件名,sql语句）
public ThreadUseExtends(String name1,String sqlstr)
{

filename1 = name1;
str = sqlstr;
System.out.println("I carry out this");
}
public void insert()
{
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String url = "jdbc:odbc:LW";


Connection con = DriverManager.getConnection(url);
//String testLong = r1.ReadFile(filename1);
File file=new File(filename1);
InputStream fin=new FileInputStream(file);
int fileLength=(int)file.length();


//byte[] ba = testLong.getBytes();
System.out.println("str=" + str);

PreparedStatement stm = con.prepareStatement(str);

stm.setBinaryStream(1,fin,fileLength);

stm.execute();
stm.close();
con.close();
}
catch (Exception e)
{
e.printStackTrace();
}

}
//本函数用于把数据库的内容从数据库中读出，并保存在文件中。
public void getCover() {
InputStream in=null;
Connection cn = null;
PreparedStatement pst = null;
byte buf[]=new byte[50000];
DataOutputStream output=null;
int size;
System.out.println("have carry out this");
try
{
output=new DataOutputStream(new FileOutputStream("D: est2.jpg"));
}
catch(IOException e)
{
System.err.println("File not opened "+e.toString());
System.exit(1);
}
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String url = "jdbc:odbc:LW";
cn = DriverManager.getConnection(url);
pst=cn.prepareStatement("SELECT data FROM Ss where ID =´0012´");
// pst.setString(1,id);
ResultSet rs=pst.executeQuery();
while(rs.next())
{
in=rs.getBinaryStream("data");
while ((size=in.read(buf,0,50000))!=-1) {
output.write(buf,0,size);
}
}
}
catch (SQLException sqle) {
System.err.println("Error in CoverServlet : getCover()-" + sqle);
sqle.printStackTrace() ;
}
catch (Exception e)
{
e.printStackTrace();
}

finally {
try {
pst.close() ;
cn.close() ;
}
catch (Exception e) {
e.printStackTrace();
}
}

}

}//ThreadUseExtends class[@more@]