jsp页面file标签上传图片以及blob类型数据库存取。

我的jsp页面表单如下：

<form name="form1" action="/YiQu/AddUserServlet?jurisdiction=1" method="post" enctype="multipart/form-data">

    <table align="center">
    <tr>
    <td>用户id：</td>
    <td><input type="text" name="userid"  ></td>
    </tr>
    <tr>
    <td>用户名：</td>
    <td><input type="text" name="username" ></td>
    </tr>
    <tr>
    <td>密码：</td>
    <td><input type="password" name="userpassword" ></td>
    </tr>
    <tr>
    <td>昵称：</td>
    <td><input type="text" name="usernickname" ></td>
    </tr>
    <tr>
    <td>头像：</td>
    <td><input type="file"  name="userpicture"  accept="image/*"></td>
    </tr>
    <tr>
    <td>个性签名：</td>
    <td><input type="text" name="userdescription" ></td>
    </tr>
    <tr>
    <td>mabeyuse：</td>
    <td><input type="text" name="mabeyuse" ></td>
    </tr>
    <tr>
    <td>生日：</td>
    <td><input type="date" name="userdate" ></td>
    </tr>
    <tr>
    <td>性别：</td>
    <td><input type="radio" name="usersex" value="男" checked>男&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    <input type="radio" name="usersex" value="女" >女</td>
    </tr>
    <tr>
    <td>地址：</td>
    <td><input type="text" name="useraddr" ></td>
    </tr>
    <tr>
    <td>邮箱：</td>
    <td><input type="text" name="usermail" ></td>
    </tr>
    <tr>
    <td>电话：</td>
    <td><input type="text" name="usertel" ></td>
    </tr>
    <tr>
    <td>支付宝：</td>
    <td><input type="text" name="useralipayid" ></td>
    </tr>
    <tr>
    <td>权限：</td>
    <td><input type="text" name="jurisdiction" ></td>
    </tr>
    <tr>
    <td></td>
    <td><input type="submit"  value="添加"></td>
    </tr>
    </table>
   </form>
</body>

我想要后台提取file标签上传的图片，然后存到mysql数据库，一开始我使用默认方式进行提交表单，发现只能获取file标签上传图片的名字，并不能获取图片内容，

那么我就要将表单以二进制流的形式进行提交，

表单默认：enctype="application/x-www-form-urlencoded"，

我需要将它改为：enctype="multipart/form-data"，这时候提交的表单就是二进制流数据，

既然是以数据流上传，那么后台request.getParameter("")获取不到数据，只有经过解析后获取标签内容，

这里要用到Apache的commons-fileupload.jar 然而这个jar包基于commons-io.jar ,所以要导入这两个jar包：

commons-fileupload.jar

commons-io.jar

导入之后编写后台接收servlet

我的servlet如下：

public class AddUserServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
     private String savePath;
     private ServletContext sc;

     public void init(ServletConfig config) {
             savePath="upload";          // 项目下用于存放图片的文件夹
            sc = config.getServletContext(); // 获取上下文
        }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        Map<String, String> map=new HashMap<>();　　// 用于存储表单非二进制流部分
        boolean isMultipart = ServletFileUpload.isMultipartContent(request);// 检查输入请求是否为multipart表单数据。
        if (isMultipart == true) {   // 如果是二进制流形式的表单
            FileItemFactory factory = new DiskFileItemFactory();// 通过它来解析请求。执行解析后，所有的表单项目都保存在一个List中。
            ServletFileUpload upload = new ServletFileUpload(factory);
            List<FileItem> items = null;
            File savedFile=null;
            try {
                items = upload.parseRequest(request);
            } catch (FileUploadException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            Iterator<FileItem> itr = items.iterator();
            while (itr.hasNext()) {
                FileItem item = (FileItem) itr.next();

                if (item.isFormField()) {//检测是否为普通表单 如果是普通表单项目，将其名字与对应的value值放入map中。
                    String fieldName = item.getFieldName();
                    map.put(fieldName, item.getString("UTF-8"));//获取表单value时确定数据格式，如果不写，有中文的话会乱码

                } else {   //如果是提交的图片
                     File fullFile=new File(item.getName()); //获取提交的文件
                     savedFile=new File(sc.getRealPath("/")+savePath,fullFile.getName()); //在项目下新建该文件，
                     try {
                        item.write(savedFile); //写入文件

                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                }
            }
            out.println("  Map"+map.toString());
            out.println(" username="+map.get("username"));
            out.println(map.get("userid")+" "+ map.get("username")+" "+ map.get("userpassword")+" "+map.get("usernickname")+" "+null+" "+map.get("userdescription")+" "+map.get("mabeyuse")+" "+Date.valueOf("".equals(map.get("userdate"))?"2012-1-1":map.get("userdate"))+" "+map.get("usersex")+" "+map.get("useraddr")+" "+map.get("usermail")+" "+map.get("usertel")+" "+ map.get("useralipayid")+" "+ map.get("jurisdiction"));
            FileInputStream str=new FileInputStream(savedFile);//将保存的文件转换为输入流
            int length=str.available();//获取输入流的长度；　　　　　　　　//下面是我将自己的普通表单内容放到User对象中
             User user=new User(0, map.get("username"), map.get("userpassword"), map.get("usernickname"), null, map.get("userdescription"), Integer.parseInt(map.get("mabeyuse")==""?"0":map.get("mabeyuse")), Date.valueOf("".equals(map.get("userdate"))?"2012-1-1":map.get("userdate")), map.get("usersex"), map.get("useraddr"), map.get("usermail"), map.get("usertel"), map.get("useralipayid"), Integer.parseInt(map.get("jurisdiction")==""?"0":map.get("jurisdiction")));
             UserDao userDao=new UserDaoImpl();
             boolean flag=userDao.addUser(user,str,length);//这步是将user对象，输入流，和输入流的长度传到 userdao的addUser方法中 用于添加到数据库；
             if(flag){
                 response.sendRedirect("/xxx/UserServlet");
             }else{
                    response.getWriter().print("<script type=\"text/javascript\">alert(\"添加失败\");location.href(\"/xxx/addUser.jsp\");</>");
             }
        } else {
            out.print("the enctype must be multipart/form-data");
        }
        }

}

我的addUser方法如下：

//插如数据库操作，主要是 pst.setBinaryStream(4,file,length);将输入流存入数据库blob类型数据中public boolean updateUser(User user,FileInputStream file,int length) {
        boolean flag=true;
        String sql="update user set username=? ,"+" userpassword=? ,"
                +" usernickname=? ,"
                +" userpicture=? ,"
                +" userdescription=? ,"
                +" mabeyuse=? ,"
                +" userdate=? ,"
                +" usersex=? ,"
                +" useraddr=? ,"
                +" usermail=? ,"
                +" usertel=? ,"
                +" useralipayid=? ,"
                +" jurisdiction=? "
                +"where userid=? ";
        try {
            pst=conn.prepareStatement(sql);
            pst.setString(1, user.getUsername());
            pst.setString(2, user.getUserpassword());
            pst.setString(3, user.getUsernickname());
            pst.setBinaryStream(4,file,length);
            pst.setString(5, user.getUserdescription());
            pst.setInt(6, user.getMabeyuse());
            pst.setDate(7, user.getUserdate());
            pst.setString(8, user.getUsersex());
            pst.setString(9, user.getUseraddr());
            pst.setString(10, user.getUsermail());
            pst.setString(11, user.getUsertel());
            pst.setString(12, user.getUseralipayid());
            pst.setInt(13, user.getJurisdiction());
            pst.setInt(14, user.getUserid());
            flag=pst.execute();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            DBUtils.closeAll(conn, pst, res);
        }
        return !flag;
    }

将file标签上传内容存入数据库到这就完成了。

下面要做的是从数据库读取blob数据,并显示到jsp界面：

我的jsp显示界面如下：

<table class="tablelist">
        <thead>
        <tr>
        <th><input  id="allSelect" type="checkbox" value="" /></th>
        <th>用户编号</th>
        <th>用户名</th>
        <th>密码</th>
        <th>昵称</th>
        <th>头像</th>
        <th>个人描述</th>
        <th>maybe</th>
        <th>用户生日</th>
        <th>用户性别</th>
        <th>收货地址</th>
        <th>邮箱</th>
        <th>手机号</th>
        <th>支付宝账号</th>
        <th>权限</th>
        </tr>
        </thead>
        <tbody>
        <c:forEach items="${userpage.data }" var="user">
        <tr>
        <td><input name="isSelect" id="${user.userid}" type="checkbox" onchange="selUser(${user.userid})"/></td>
        <td>${user.userid}</td>
        <td>${user.username}</td>
        <td>${user.userpassword}</td>
        <td>${user.usernickname}</td>
        <td><img alt="" width="100px" height="75px" src="/xxx/upload/${user.userdescription}.jpg">
        </td>
        <td>${user.userdescription}</td>
        <td>${user.mabeyuse}</td>
        <td>${user.userdate}</td>
        <td>${user.usersex}</td>
        <td>${user.useraddr}</td>
        <td>${user.usermail}</td>
        <td>${user.usertel}</td>
        <td>${user.useralipayid}</td>
        <td>${user.jurisdiction}</td>
        </tr>
        </c:forEach>
        </tbody>
    </table>

图片用img标签显示 用src读取服务器上图片路径：

我从数据库用getBlob（）方法获取blob类型数据，然后新建User对象进行封装这里就不讲了。

后台将blob数据转化为图片的代码如下：

@WebServlet("/UserServlet")
public class UserServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("image/*");
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        String scurrentpage=request.getParameter("currentpage");
        if(scurrentpage==null){
            scurrentpage="1";
        }
        UserDao userDao=new UserDaoImpl();
        UserPage uPage= userDao.findUserByPage(Integer.parseInt(scurrentpage), 5);
        List<User> list=uPage.getData(); //这里是获取分页查询到的User对象的List 下面遍历每个User
        for (User us : list) {
            if (us.getUserpicture()==null||us.getUserpicture().equals("")) {
                continue;
            }else{
            try {
                InputStream is=us.getUserpicture().getBinaryStream(); //获取Blob类型变量 并转化为二进制输入流
                 if(is!=null){
                         String uuid=UUID.randomUUID().toString();  //给图片取个独一无二的名字
                        is = new BufferedInputStream(is) ;  //将输入流读入缓冲区
                        BufferedImage bi = ImageIO.read(is) ; //利用ImageIo对象转化为Image对象
                        OutputStream oi=new FileOutputStream("D:/tomcat8/webapps/xxx/upload/"+uuid+".jpg");//新建输出流 保存文件到服务器指定路径
                        ImageIO.write(bi, "jpeg", oi); //写入文件
                        oi.close();
                        is.close();
                        us.setUserdescription(uuid);//我将图片名字存入User对象中，方便jsp界面读取

                 }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            }
        }

        request.setAttribute("userpage", uPage);
        request.getRequestDispatcher("/user.jsp").forward(request, response);
    }

}//在jsp页面读取和读取服务器图片相同//至此向数据库存入图片，以及从数据库读取图片显示到jsp界面 均已完成。