将图像从android上传到java servlet并保存

Question

我一直在寻找这个,没有什么对我有用.

我正在尝试将图像从Android应用程序上传到java servlet并将其保存在服务器中.我找到的每个解决方案都不适用于我.

我的代码目前做了什么:android应用程序将图像发送到servlet,当我试图保存它时,文件被创建,但它是空的:(

谢谢你的帮助!

我在android客户端的代码(i_file是设备上的文件位置):

public static void uploadPictureToServer(String i_file) throws ClientProtocolException, IOException {
    // TODO Auto-generated method stub   
    HttpClient httpclient = new DefaultHttpClient();
    httpclient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);

    HttpPost httppost = new HttpPost("http://192.168.1.106:8084/Android_Server/GetPictureFromClient");
    File file = new File(i_file);

    MultipartEntity mpEntity = new MultipartEntity();
    ContentBody cbFile = new FileBody(file, "image/jpeg");
    mpEntity.addPart("userfile", cbFile);

    httppost.setEntity(mpEntity);
    System.out.println("executing request " + httppost.getRequestLine());
    HttpResponse response = httpclient.execute(httppost);
    HttpEntity resEntity = response.getEntity();

    System.out.println(response.getStatusLine());
    if (resEntity != null) {
      System.out.println(EntityUtils.toString(resEntity));
    }
    if (resEntity != null) {
      resEntity.consumeContent();
    }

    httpclient.getConnectionManager().shutdown();

}

我在服务器端的代码:

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);

        InputStream in = request.getInputStream();
        OutputStream out = new FileOutputStream("C:\\myfile.jpg");
        IOUtils.copy(in, out); //The function is below
        out.flush();
        out.close();

}

IOUtils.copy代码:

public static long copy(InputStream input, OutputStream output) throws IOException {
    byte[] buffer = new byte[4096];

    long count = 0L;
    int n = 0;

    while (-1 != (n = input.read(buffer))) {
        output.write(buffer, 0, n);
        count += n;
    }
    return count;
}

Answer 1

你误解了这个问题.图像文件不为空,但图像文件已损坏,因为您将整个HTTP多部分请求主体存储为图像文件,而不是从HTTP多部分请求主体中提取包含该图像的部分.

您需要HttpServletRequest#getPart()获取多部分请求正文的部分.如果您已经使用Servlet 3.0(Tomcat 7,Glassfish 3等),请先使用.注释您的servlet@MultipartConfig

@WebServlet("/GetPictureFromClient")
@MultipartConfig
public class GetPictureFromClient extends HttpServlet {
    // ...
}

然后doPost()按如下方式修复你的部分,按名称抓取部分,然后将其作为输入流:

InputStream in = request.getPart("userfile").getInputStream();
// ...

如果你还没有使用Servlet 3.0,那么就抓住Apache Commons FileUpload.有关详细示例,请参阅此答案:如何使用JSP/Servlet将文件上载到服务器？

哦,请摆脱Netbeans生成的processRequest()方法.这绝对不是委托双方的正确方法doGet(),并doPost()以一个单一的processRequest()方法,它会只会混淆其他开发者和维护者谁不使用NetBeans.