檔案在資料庫中要搞清楚下面幾個內容:
1   mysql儲存大容量的二進位制檔案的格式是blob，其實除了圖片還可以存別的
2   要向資料庫儲存二進位制的檔案一定要把要儲存的資料轉換成二進位制流
廢話就不多說了，大家看看程式碼很容易明白，先來看一個app程式，當然首先您要在資料庫
中先建立一個用於儲存圖片的表和相應的列，資料格式為blob

package com.lizhe;
import java.io.*;
import java.sql.*;
public class PutImg {
 public void putimg() {
  try {
   Class.forName("org.gjt.mm.mysql.Driver").newInstance();
   String url = "jdbc:mysql://localhost/img?user=root&password=root&useUnicode=
true&characterEncoding=gbk";
   Connection conn = DriverManager.getConnection(url);
   Statement stmt = conn.createStatement();
   //stmt.execute("insert   into   imgt (id)   values   (5)");
   stmt.close();
   PreparedStatement pstmt = null;
   String sql = "";
   File file = new File("c:\\blog.jpg");
   InputStream photoStream = new FileInputStream(file);
   //sql = "   UPDATE   imgt   SET   img   =   ?   ";
     
   sql = "INSERT INTO imgtable  (img) VALUES (?)";
   
   pstmt = conn.prepareStatement(sql);
   pstmt.setBinaryStream(1, photoStream, (int) file.length());
   pstmt.executeUpdate();
   pstmt.close();
   conn.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
 public static void main(String args[]){
  PutImg pi=new PutImg();
  pi.putimg();
 }
}
 
 

InputStream photoStream = new FileInputStream(file);
可以很清楚的看到我們首先把一個圖片檔案(當然也可以是別的什麼檔案)轉換成了一個二進位制輸入流
pstmt.setBinaryStream(1, photoStream, (int) file.length());
這個方法建議大家去查一下API文件,第一個引數是萬用字元位置沒的說,第二個引數是流,這和以
往的string型別的引數不太一樣,我剛看到的時候也覺得豁然開朗了,但是到這裡還沒完,不同於
以往的字串引數,這裡我們還需要第三個引數來設定這個流的長度,這裡也就是這個檔案的長
度,匯出資料庫中的sql,一切都清楚了
INSERT INTO `m_diy` VALUES (2,?\0 JFIF\0   \0H\0H\0\0?? Exif\0\0MM\0*\0\0\0 \0
 \0 \0\0\0 \0 \0\0  \0 \0\0\0 \0\0\0b  \0 \0\0\0 \0\0\0j (\0 \0\0\0 \0 \0\0 1\0 \
0\0\0 \0\0\0r 2\0 \0\0\0 \0\0\0?i\0 \0\0\0 \0\0\0\0\0\0\0\0\0H\0\0\0 \0\0\0H\0\0\0
 Adobe Photoshop CS Windows\02007:03:18 23:08:15\0\0\0\0\0 ?\0 \0\0\0 ??\0\0?\0 \0
\0\0 \0\0\0? \0 ........等等
其實就是將檔案先轉換成了二進位制的流,然後插入到了sql語言中,向資料庫寫入了很長很長的一
段sql語句

 
 
然後我們再來寫一個app程式將這個檔案讀出來,儲存成一個圖片檔案

package com.lizhe;
import java.io.*;
import java.sql.*;
class GetImg {
 
 private static final String URL = "jdbc:mysql://localhost/img?user=root&password=ro
ot&useUnicode=true&characterEncoding=gbk";
 private Connection conn = null; 
 private PreparedStatement pstmt = null; 
 private ResultSet rs = null; 
 private File file = null; 

 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 img from imgt where id=?");
   pstmt.setInt(1, picID); // 傳入要取的圖片的ID
   rs = pstmt.executeQuery();
   rs.next();
   file = new File(outfile);
   if (!file.exists()) {
    file.createNewFile(); // 如果檔案不存在，則建立
   }
   fos = new FileOutputStream(file);
   is = rs.getBinaryStream("img");
   int size = 0;
   
   while ((size = is.read(Buffer)) != -1) {
    // System.out.println(size);
    fos.write(Buffer, 0, size);
   }
  } catch (Exception e) {
   System.out.println( e.getMessage());
  } finally {
   // 關閉用到的資源
   fos.close();
   rs.close();
   pstmt.close();
   conn.close();
  }
 }
 public static void main(String[] args) {
  try {
   GetImg gi=new GetImg();
   gi.blobRead("c:/getimgs/1.jpg", 5);
  } catch (Exception e) {
   System.out.println("[Main func error: ]" + e.getMessage());
  }
 }
}

 

這裡需要注意的是
 is = rs.getBinaryStream("img");
img是資料庫中相應的列名,其實和rs.getString()方法差不多,只不過這個方法是讀取二進位制流的
最後在帖兩個bs系統上用的檔案給大家參考

通過struts的action向資料庫寫入二進位制圖片

/*
 * Generated by MyEclipse Struts
 * Template path: templates/java/JavaClass.vtl
 */
package com.lizhe.struts.action;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.Statement;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.upload.FormFile;
import com.lizhe.struts.form.UpimgForm;
/** 
 * MyEclipse Struts
 * Creation date: 05-18-2007
 * 
 * XDoclet definition:
 * @struts.action path="/upimg" name="upimgForm" input="/userhomepage.jsp"
 * @struts.action-forward name="userhome" path="/userhomepage.jsp" redirect="true" 
contextRelative="true"
 */
public class UpimgAction extends Action {
 /*
  * Generated Methods
  */
 /** 
  * Method execute
  * @param mapping
  * @param form
  * @param request
  * @param response
  * @return ActionForward
  * @throws IOException 
  * @throws FileNotFoundException 
  */
 public ActionForward execute(ActionMapping mapping, ActionForm form,
   HttpServletRequest request, HttpServletResponse response) throws FileNotFoundE
xception, IOException {
  UpimgForm upimgForm = (UpimgForm) form;// TODO Auto-generated method stub
  
  FormFile file=upimgForm.getFile();
  InputStream is=file.getInputStream();
  
  try {
   Class.forName("org.gjt.mm.mysql.Driver").newInstance();
   String url = "jdbc:mysql://localhost/blog?user=root&password=root&useUnicode=t
rue&characterEncoding=gb2312";
   Connection conn = DriverManager.getConnection(url);
   Statement stmt = conn.createStatement();
   //stmt.execute("insert   into   img (id)   values   (5)");
   stmt.close();
   PreparedStatement pstmt = null;
   String sql = "";
   //File file = new File("c:\\blog.jpg");
   //InputStream photoStream = new FileInputStream(file);
   //sql = "   UPDATE   imgt   SET   img   =   ?   ";
     
   sql = "INSERT INTO img (img) VALUES (?)";
   
   pstmt = conn.prepareStatement(sql);
   pstmt.setBinaryStream(1, is, (int) file.getFileSize());
   pstmt.executeUpdate();
   pstmt.close();
   conn.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
  
  return mapping.findForward("userhomepage");
 }
}

和app的方式幾乎是一樣的
第二個檔案是通過jsp將資料庫中的圖片顯示在頁面上
這個有些不同
     

其中在oracle資料庫中也可以如此使用，確保資料的安全哦！可以不用儲存路徑的方法