/**
* @param strID 图片字段ID
* @param w 需要缩到的宽度
* @param h 需要缩到高度
* @return
*/
public byte[] GetImgByteById(String strID, int w, int h){
//System.out.println("Get img data which id is " + nID)
if(myConnection == null)
this.getConnection()
byte[] data = null
try {
Statement stmt = myConnection.createStatement()
ResultSet myResultSet = stmt.executeQuery("select " + this.strIDName + " from " + this.strTabName + " where " + this.strIDName + "=" + strID)
StringBuffer myStringBuffer = new StringBuffer()
if (myResultSet.next()) {
java.sql.Blob blob = myResultSet.getBlob(this.strImgName)
InputStream inStream = blob.getBinaryStream()
try {
long nLen = blob.length()
int nSize = (int) nLen
//System.out.println("img data size is :" + nSize)
data = new byte[nSize]
inStream.read(data)
inStream.close()
} catch (IOException e) {
System.out.println("获取图片数据失败,原因:" + e.getMessage())
}
data = ChangeImgSize(data, w, h)
}
System.out.println(myStringBuffer.toString())
myConnection.commit()
myConnection.close()
} catch (SQLException ex) {
System.out.println(ex.getMessage())
}
return data
}
页面使用OracleQueryBean来根据用户提供的图片id进行查询，在读取并进行缩放后，通过jsp页面进行展示，具体代码如下：
<%@ page language="java" contentType="text/htmlcharset=gbk" %>
<jsp:useBean id="OrcleQuery" scope="page" class="HLFtiDemo.OracleQueryBean" />
<%
response.setContentType("image/jpeg")
//图片在数据库中的 ID
String strID = request.getParameter("id")
//要缩略或放大图片的宽度
String strWidth = request.getParameter("w")
//要缩略或放大图片的高度
String strHeight = request.getParameter("h")
byte[] data = null
if(strID != null){
int nWith = Integer.parseInt(strWidth)
int nHeight = Integer.parseInt(strHeight)
//获取图片的byte数据
data = OrcleQuery.GetImgByteById(strID, nWith, nHeight)
ServletOutputStream op = response.getOutputStream()
op.write(data, 0, data.length)
op.close()
op = null
response.flushBuffer()
//清除输出流，防止释放时被捕获异常
out.clear()
out = pageContext.pushBody()
}
%>
/*** 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())
}
}
}
