java对blob的存取.doc

java对blob的存取 作者:未知 时间:2005-09-13 23:33 出处:Blog.ChinaU 责编:chinaitpower 摘要：java对blob的存取此实现为用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:/3:3306/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 byte4096; 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.blob