JAVA Mysql中如何实现Blob的存取 -2

 此实现为用java访问mysql的blob,对图片进行存取

  /**

  * Title: BlobPros.java

  * Project: test

  * Description: 把图片存入mysql中的blob字段,并取出

  * Call Module: mtools数据库中的tmp表

  * File: C:downloadsluozsh.jpg

  * Copyright: Copyright (c) 2003-2003

  * Company: uniware

  * Create Date: 2002.12.5

  * @Author: ChenQH

  * @version 1.0 版本*

  *

  * Revision history

  * Name Date Description

  * ---- ---- -----------

  * Chenqh 2003.12.5 对图片进行存取

  *

  * note: 要把数据库中的Blob字段设为longblob

  *

  */

  //package com.uniware;

  import java.io.*;

  import java.util.*;

  import java.sql.*;

  public class BlobPros

  {

  private static final String URL = "jdbc:mysql://10.144.123.63:3306/mtools?user=wind&password=123&useUnicode=true";

  private Connection conn = null;

  private PreparedStatement pstmt = null;

  private ResultSet rs = null;

  private File file = null;

  public BlobPros()

  {

  }

  /**

  * 向数据库中插入一个新的BLOB对象(图片)

  * @param infile 要输入的数据文件

  * @throws java.lang.Exception

  */

  public void blobInsert(String infile) throws Exception

  {

  FileInputStream fis = null;

  try

  {

  Class.forName("org.gjt.mm.mysql.Driver").newInstance();

  conn = DriverManager.getConnection(URL);

  file = new File(infile);

  fis = new FileInputStream(file);

  //InputStream fis = new FileInputStream(infile);

  pstmt = conn.prepareStatement("insert into tmp(descs,pic) values(?,?)");

  pstmt.setString(1,file.getName()); //把传过来的第一个参数设为文件名

  //pstmt.setBinaryStream(2,fis,(int)file.length()); //这种方法原理上会丢数据,因为file.length()返回的是long型

  pstmt.setBinaryStream(2,fis,fis.available()); //第二个参数为文件的内容

  pstmt.executeUpdate();

  }

  catch(Exception ex)

  {

  System.out.println("[blobInsert error : ]" + ex.toString());

  }

  finally

  {

  //关闭所打开的对像//

  pstmt.close();

  fis.close();

  conn.close();

  }

  }

  /**

  * 从数据库中读出BLOB对象

  * @param outfile 输出的数据文件

  * @param picID 要取的图片在数据库中的ID

  * @throws java.lang.Exception

  */

  public void blobRead(String outfile,int picID) throws Exception

  {

  FileOutputStream fos = null;

  InputStream is = null;

  byte[] Buffer = new byte[4096];

  try

  {

  Class.forName("org.gjt.mm.mysql.Driver").newInstance();

  conn = DriverManager.getConnection(URL);

  pstmt = conn.prepareStatement("select pic from tmp where id=?");

  pstmt.setInt(1,picID); //传入要取的图片的ID

  rs = pstmt.executeQuery();

  rs.next();

  file = new File(outfile);

  if(!file.exists())

  {

  file.createNewFile(); //如果文件不存在,则创建

  }

  fos = new FileOutputStream(file);

  is = rs.getBinaryStream("pic");

  int size = 0;

  /* while(size != -1)

  {

  size = is.read(Buffer); //从数据库中一段一段的读出数据

  //System.out.println(size);

  if(size != -1) //-1表示读到了文件末

  fos.write(Buffer,0,size);

  } */

  while((size = is.read(Buffer)) != -1)

  {

  //System.out.println(size);

  fos.write(Buffer,0,size);

  }

  }

  catch(Exception e)

  {

  System.out.println("[OutPutFile error : ]" + e.getMessage());

  }

  finally

  {

  //关闭用到的资源

  fos.close();

  rs.close();

  pstmt.close();

  conn.close();

  }

  }

  public static void main(String[] args)

  {

  try

  {

  BlobPros blob = new BlobPros();

  //blob.blobInsert("C:Downloadsluozsh1.jpg");

  blob.blobRead("c:/downloads/1.jpg",47);

  }

  catch(Exception e)

  {

  System.out.println("[Main func error: ]" + e.getMessage());

  }

  }

  }


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