jsp通过从数据库读取的字节流(byte[])制作图片

1、怎样将文件以字节流(byte[])存入数据库,在数据库中存放字节流的类型为image

如：

PreparedStatement ps = CatenateDB.prepare(conn, sql);       String F = src+"\\"+f; //文件路径(包含文件名)       try {          InputStream is = new FileInputStream(F);          ps.setBinaryStream(1, is, is.available());          int count = ps.executeUpdate();          if(count>0){                i=1;            }else{                i=-1;            }       } catch (Exception e) {          e.printStackTrace();       }

注意：下面方法的conn为连接数据库的类对象，sql是将更新上图所示的表格的head字段

2、怎样将数据库中存放的字节流转换成图片

页面上读取从数据库读取的字节流生成的图片的方法：

 <img src="index/makeImage.jsp?id=124"></img>

makeImage.jsp源码：

<%@ page contentType="image/jpeg" pageEncoding="gbk"%><%@ page import="com.other.MakeImage" %><%   try{      int id = Integer.parseInt(request.getParameter("id")); //用户userid      new MakeImage(id,response.getOutputStream());   }catch(Exception e){        }   out.clear();   out = pageContext.pushBody();%>

com.other.MakeImage.java源码：

/** * @System: Online CV System * @Version:1.0 * Copyright @ 2011 by GuangDongOceanUniversity * Class: * Sumarry：从数据库读取二进制字节流(byte[])到页面中生成图片 * Create: 2011.12.31 * Update: */package com.other;import java.io.IOException;import java.io.OutputStream;import java.util.ArrayList;import com.microbolg.DaoMicrobolg;public class MakeImage{    /* 方法：  MakeImage    * 描述：  从数据库读取二进制字节流(byte[])到页面中生成图片    * 输入：  int userid 用户ID , OutputStream os 从数据库读取的图片二进制字节流    * 返回：     * 异常处理：    */   public MakeImage(int userid,OutputStream os)throws IOException{       DaoMicrobolg dao = new DaoMicrobolg();       ArrayList<Object> array = dao.searchImage(userid);       os.write((byte[])array.get(0), 0, ((byte[])array.get(0)).length);         os.flush();         os.close();        }   }

com.microbolg.DaoMicrobolg类中的searchImage方法：

public ArrayList<Object> searchImage(int userid) { //通过微博信息表的userid获取用户头像字节流       Connection conn = CatenateDB.createConn();       String sql = "select head from user_message where userid=?";       PreparedStatement ps = CatenateDB.prepare(conn, sql);       ArrayList<Object> array = new ArrayList<Object>();       try {          ps.setInt(1,userid);          ResultSet rs = ps.executeQuery();          while(rs.next()){                 array.add(rs.getBytes(1));          }       } catch (SQLException e) {          e.printStackTrace();       }       CatenateDB.close(ps);       CatenateDB.close(conn);       return array;   }

CatenateDB.java：

package com.util.jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class CatenateDB {public static Connection createConn() {Connection conn = null;try {Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");conn = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;DatabaseName=microbolg", "sa", "");} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}return conn;}public static PreparedStatement prepare(Connection conn, String sql) {PreparedStatement ps = null;try {ps = conn.prepareStatement(sql);} catch (SQLException e) {e.printStackTrace();}return ps;}public static void close(Connection conn) {try {conn.close();conn = null;} catch (SQLException e) {e.printStackTrace();}}public static void close(Statement stmt) {try {stmt.close();stmt = null;} catch (SQLException e) {e.printStackTrace();}}public static void close(ResultSet rs) {try {rs.close();rs = null;} catch (SQLException e) {e.printStackTrace();}}}