blobbean.java

这是一个jsp学习的事例 不是很难 地是对处学者非常的有用

package com.jspdev.ch13;
import com.jspdev.util.*;
import java.sql.*;
import javax.sql.*;
import java.io.*;
//import oracle.jdbc.driver.OracleResultSet;
//import oracle.sql.BLOB;
public class BlobBean
{

   Connection conn ;
   /**
    *构造方法,创建Connection对象，并且在数据库中添加一个表。
    */
   public BlobBean()throws Exception
   {
   	
   		//DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
   		Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
       conn = DriverManager.getConnection("jdbc:microsoft.server://localhost:1433;DatabaseName=jspdev", "sa", "sa");
      // conn.createStatement().execute("create table  blobtable(blobvalue blob)");
    }
    
    /**
     *写入Blob数据到数据库
     */
	public void addBlob(String fileName)throws Exception
	{
	        
	        conn.setAutoCommit(false);
            Statement stmt = conn.createStatement();
            stmt.execute("insert into blobtable values (empty_blob())");
            ResultSet rset = stmt.executeQuery("SELECT blobvalue FROM blobtable FOR UPDATE");
            BLOB blob = null;
            while (rset.next()) {
                blob = ((OracleResultSet) rset).getBLOB(1);
                System.out.println(blob.length());
            }
            File binaryFile = new File(fileName);
            System.out.println(fileName+"'s length = " + binaryFile.length());
            FileInputStream instream = new FileInputStream(binaryFile);
            OutputStream outstream = blob.getBinaryOutputStream();
            int chunk = blob.getChunkSize();
            System.out.println("chunk size = " + chunk);
            byte[] buffer = new byte[chunk];
            int length = -1;
            while ((length = instream.read(buffer)) != -1)
                outstream.write(buffer, 0, length);
            instream.close();
            outstream.close();
            conn.commit();

        }
        
        /**
         *从数据库读取blob数据，并且保存在文件系统。
         */
     public void readBlob(String fileName)throws Exception
	  {
	        
	        conn.setAutoCommit(false);
            Statement stmt = conn.createStatement();
            ResultSet rset = stmt.executeQuery("SELECT blobvalue FROM blobtable");
            BLOB blob = null;
            while (rset.next()) {
                blob = ((OracleResultSet) rset).getBLOB(1);
                System.out.println(blob.length());
            }

            FileOutputStream file_out = new FileOutputStream(new File(fileName));
            InputStream blob_in = blob.getBinaryStream();
            int temp;
            while((temp=blob_in.read())!=-1)
            file_out.write(temp);//读取数据、写入文件系统
           
            file_out.close();
            blob_in.close();
            conn.commit();
        }        	
         
}