在jsp中使用commons-fileupload将图片上传至mysql数据库，再用servlet将其显示

来源：互联网发布：ubuntu怎么安装程序编辑：程序博客网时间：2024/06/07 00:30

本文将阐述怎么使用commons-fileupload将图片上传至mysql数据库，并利用java servlet将其在浏览器中显示

出来。

前提条件：

正确安装了mysql,tomcat,并下载了commons-fileupload-1.0.jar。

1，前台页面

---test_upload.htm---

<html>
<head>
<title>
上传测试
</title>
<body>
<form action="upload.jsp" enctype="multipart/form-data" method="post">
your name:
<br>
<input type="text" name="name">
<br>
file to process:
<input type="file" name="userfile">
<br>
<input type="submit">
</form>
</body>
</html>

2，上传的后台处理页面

---upload.jsp---

<%@ page contentType="text/html; charset=gb2312" %>
<%@ page import="java.io.*" %>
<%@ page import="java.sql.*"%>

<%@ page import="java.util.*"%>
<%@ page import="org.apache.commons.fileupload.*" %>
<%@ page import="com.cf.model.DbManipulate" %>
<%
        DiskFileUpload upload=new DiskFileUpload();
        upload.setSizeThreshold(4096);
        upload.setRepositoryPath("d:/java/");
        upload.setSizeMax(10000000);
        List fileItems = upload.parseRequest(request);
        Iterator i = fileItems.iterator();
        String name = ((FileItem)i.next()).getString();
        FileItem fi = (FileItem)i.next();
        String fileName = fi.getName();
  //System.out.println(fileName);
  fileName = fileName.replace(':','_');
        fileName = fileName.replace('//','_');
  //System.out.println(fileName);
        //File savedFile = new File("d:/java/upload/",fileName);
        //fi.write(savedFile);
  InputStream fis=fi.getInputStream();
        DbManipulate dm=new DbManipulate();
  Long long_size=new Long(fi.getSize());
  int size=long_size.intValue();
  PreparedStatement ps=dm.DbUpdate("insert into photo(image,description) values(?,?)");
  ps.setBinaryStream(1,fis,size);
  ps.setString(2,fileName);
  ps.executeUpdate();
  String sql="select id from photo order by id desc limit 1";
  PreparedStatement ps2=dm.DbQuery(sql);
  ResultSet rs=ps2.executeQuery();
  int index=0;
  if(rs.next())
  {
   index=rs.getInt(1);
  }
  //ps.close();
  //fis.chose();
%>
<%=name%> <a href="javascript:history.go(-1)">go on</a>
<br>
<iframe height="600" width="800" src=photoview?id=<%=index%> scrolling=true>

3，显示图片的servlet

---BlobServlet.java----

package com.cf.photo;

import java.io.*;
import java.sql.*;
import javax.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
//import org.apache.commons.logging.Log;
//import org.apache.commons.logging.LogFactory;

import com.cf.model.*;

public class BlobServlet extends HttpServlet{
//private static Log log = LogFactory.getLog(BlobServlet.class);

protected void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException{

  ServletOutputStream out=response.getOutputStream();
  int id=Integer.parseInt(request.getParameter("id"));
  response.setContentType("image/jpeg");
  out.write(getBlob(id));
  out.flush();
  out.close();
}
public byte[] getBlob(int photoid){
  String sql="select image from photo where id=?";
  //log.info(sql);
  Blob blob=null;
  byte[] bytes=null;
  //String description="";
  PreparedStatement pstmt=null;
  ResultSet rs=null;
  DbManipulate mydb=new DbManipulate();
  try{
   pstmt=mydb.DbQuery(sql);
   pstmt.setInt(1,photoid);
   rs=pstmt.executeQuery();
   while(rs.next()){
    blob=rs.getBlob(1);
   }
   bytes=blob.getBytes(1,(int)(blob.length()));
  }catch(SQLException e){}
  return bytes;
}
}

4，存储图片的表定义：

create database web_exam;

use web_exam;

create table photo(

id int not null auto_increment primary key,

image mediumblob not null,

description varchar(100) null

);

5，应用程序的目录结构

%catalina_home%/webapps/demo

------test_upload.htm

------upload.jsp

------WEB-INF

|----web.xml

|-----build.xml

|-----lib

|-------mysql-connector-java-3.0.16-ga-bin.jar

|-------commons-fileupload-1.0.jar

|----src

|----com

|-----cf

|-----photo

|-----BlobServlet.java

|-----model

|----DbConnection.java

|----DbConst.java

|----DbManipulate.java

6，web.xml文件内容

<?xml version="1.0"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/j2ee/dtds/web-app_2_3.dtd">

<web-app>

<servlet>
        <servlet-name>photoview</servlet-name>
        <servlet-class>com.cf.photo.BlobServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>photoview</servlet-name>
        <url-pattern>/photoview/*</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
       <welcome-file>default.jsp</welcome-file>
       <welcome-file>index.jsp</welcome-file>
       <welcome-file>test.jsp</welcome-file>
       </welcome-file-list>

</web-app>

7，ant的buildfile内容

------build.xml------

8，DbConst.java

package com.cf.model;

public interface DbConst{
public final static String JDBC_DRIVER="com.mysql.jdbc.Driver";
public final static String JDBC_URL="jdbc:mysql://localhost:3306/web_exam?"
+"useUnicode=true&characterEncoding=GB2312";
public final static String JDBC_USER="root";
public final static String JDBC_PASS="chenfu";
}

9，DbConnection.java

package com.cf.model;
import java.sql.*;
public class DbConnection implements DbConst{

    private String jdbcDriver=JDBC_DRIVER;
private String databaseURL=JDBC_URL;
private String dbUsername=JDBC_USER;
private String dbPassword=JDBC_PASS;
private Connection con=null;
public String getJdbcDriver(){
  return this.jdbcDriver;
}
public void setJdbcDriver(String d){
  this.jdbcDriver=d;
}
public String getDatabaseURL(){
  return this.databaseURL;
}
public void setDatabaseURL(String url){
  this.databaseURL=url;
}
public String getDbUsername(){
  return this.dbUsername;
}
public void setDbUsername(String u){
  this.dbUsername=u;
}

public String getDbPassword(){
  return this.dbPassword;
}
public void setDbPassword(String p){
  this.dbPassword=p;
}
public boolean isConnected(){
  return (con!=null);
}
public void disconnected(){
  if(con!=null){
   try
   {
    con.close();
   }
   catch (SQLException ignore)
   {
   }
   finally {
    con=null;
   }
  }
}
public void setCon(Connection c){
  this.con=c;
}
public Connection getCon() throws SQLException{
  if(isConnected()) throw new SQLException("Already connected");
  if(jdbcDriver==null) throw new SQLException("No jdbcDriver property");
  if(databaseURL==null) throw new SQLException("No jdbcURL property");
  try
  {
   Class.forName(jdbcDriver);
   //log.info(jdbcDriver);
  }
  catch (ClassNotFoundException e)
  {
   throw new SQLException(jdbcDriver+"class could not loaded");
  }
  con=DriverManager.getConnection(databaseURL,dbUsername,dbPassword);
  return con;
}
}

10，DbManipulate.java

package com.cf.model;
import java.sql.*;
public class DbManipulate{
private Connection con=null;
private PreparedStatement pstmt=null;

public PreparedStatement DbQuery(String sql)throws SQLException{
  DbConnection newcon=new DbConnection();
  con=newcon.getCon();
  pstmt=con.prepareStatement(sql,
  ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
  //log.info(sql);
  return pstmt;
}
public PreparedStatement DbUpdate(String sql)throws SQLException{
  DbConnection newcon=new DbConnection();
  con=newcon.getCon();
  pstmt=con.prepareStatement(sql);
  return pstmt;
}
public void DbClose(){
   if(pstmt!=null){
    pstmt=null;
     }
}
}

11，转到该web application的WEB-INF下，在命令行中执行ant，以编译源文件，然后打开tomcat服务器，

在浏览器中打开地址：http://localhost:8080/demo/test_upload.htm,试着去上传一张jpg的图片,看看行不行。

12，欢迎大家提出宝贵意见，请联系我：

email:cf0124@163.com

msn:cf_asp_master@yahoo.com.cn