android form表单上传文件

原文地址：http://menuz.iteye.com/blog/1282097

Android程序使用http上传文件 

有时，在网络编程过程中需要向服务器上传文件。Multipart/form-data是上传文件的一种方式。 

Multipart/form-data其实就是浏览器用表单上传文件的方式。最常见的情境是：在写邮件时，向邮件后添加附件，附件通常使用表单添加，也就是用multipart/form-data格式上传到服务器。 

<form action=“/TestWeb/command=UpdatePicture” method=”post” enctype=”multipart/form-data”>
    <input type=”file” name=”uploadfile1”/><br>
    <input type=”file” name=”uploadfile2”/><br>
    <input type=”submit” value=”uploadfile”>
</form>

内容如下： 
Type：multipart/form-data; boundary=-----------------------------265001916915724 
-----------------------------265001916915724 
Content-Disposition: form-data; name="uploadfile1"; filename="web.txt" 
Content-Type: text/plain 

ChinaNetSNWide  
å­ç½‘æŽ©ç 255.255.255.255 简单的说四个255是全广播IP地址。就是用来从DHCP服     务器那里莕取IP地址。 
默认网关0.0.0.0 即本机 

-----------------------------265001916915724 
Content-Disposition: form-data; name="uploadfile2"; filename="20080116064637581.jpg" 
Content-Type: image/jpeg 

ÿØÿà 

-----------------------------265001916915724— 


注意点一： 
      Header 下面boundary 有27个 -（横杆） 
      POST Data 下面传输每个文件的开头是有29个 - 
注意点二： 
      观察POST Data可以发现从第一个-----------------------------265001916915724 
      到第二个-----------------------------265001916915724之间为一个txt文件的相关 
      信息。 
上面form提交的servlet不用实现，只是解析了http协议，为下面模拟铺垫。 

下面实现android客户端上传图片到服务端的servlet 
android客户端代码 

public void upload() {
       Log.d(TAG, "upload begin");
       HttpURLConnection connection = null;
       DataOutputStream dos = null;
       FileInputStream fin = null;

       String boundary = "---------------------------265001916915724";
       // 真机调试的话，这里url需要改成电脑ip
       // 模拟机用10.0.0.2,127.0.0.1被tomcat占用了
       String urlServer = "http://10.0.0.2:8080/TestWeb/command=UpdatePicture";
       String lineEnd = "\r\n";
       String pathOfPicture = "/sdcard/aaa.jpg";
       int bytesAvailable, bufferSize, bytesRead;
       int maxBufferSize = 1*1024*512;
       byte[] buffer = null;

       try {
           Log.d(TAG, "try");
           URL url = new URL(urlServer);
           connection = (HttpURLConnection) url.openConnection();

           // 允许向url流中读写数据
           connection.setDoInput(true);
           connection.setDoOutput(true);
           connection.setUseCaches(true);

           // 启动post方法
           connection.setRequestMethod("POST");

           // 设置请求头内容
           connection.setRequestProperty("connection", "Keep-Alive");
           connection.setRequestProperty("Content-Type", "text/plain");

           // 伪造请求头
           connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);


           // 开始伪造POST Data里面的数据
           dos = new DataOutputStream(connection.getOutputStream());
           fin = new FileInputStream(pathOfPicture);

           Log.d(TAG, "开始上传images");
           //--------------------开始伪造上传images.jpg的信息-----------------------------------
           String fileMeta = "--" + boundary + lineEnd +
                           "Content-Disposition: form-data; name=\"uploadedPicture\"; filename=\"" + pathOfPicture + "\"" + lineEnd +
                           "Content-Type: image/jpeg" + lineEnd + lineEnd;
           // 向流中写入fileMeta
           dos.write(fileMeta.getBytes());

           // 取得本地图片的字节流，向url流中写入图片字节流
           bytesAvailable = fin.available();
           bufferSize = Math.min(bytesAvailable, maxBufferSize);
           buffer = new byte[bufferSize];

           bytesRead = fin.read(buffer, 0, bufferSize);
           while(bytesRead > 0) {
               dos.write(buffer, 0, bufferSize);
               bytesAvailable = fin.available();
               bufferSize = Math.min(bytesAvailable, maxBufferSize);
               bytesRead = fin.read(buffer, 0, bufferSize);
           }
           dos.writeBytes(lineEnd+lineEnd);
           //--------------------伪造images.jpg信息结束-----------------------------------
           Log.d(TAG, "结束上传");

           // POST Data结束
           dos.writeBytes("--" + boundary + "--");

           // Server端返回的信息
           System.out.println("" + connection.getResponseCode());
           System.out.println("" + connection.getResponseMessage());

           if (dos != null) {
               dos.flush();
               dos.close();
           }
           Log.d(TAG, "upload success-----------------------------------------");
       } catch (Exception e) {
          e.printStackTrace();
          Log.d(TAG, "upload fail");
       }
   }

服务端servlet 

import java.io.File;
import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

// 利用该组件进行接收客户端上传的文件
// 需要自己加载commons-fileupload-1.2.2.jar和commons-io-2.1.jar
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Servlet implementation class ReceivePictureFromAndroid
 */
@WebServlet("/command=UpdatePicture")
public class ReceivePictureFromAndroid extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ReceivePictureFromAndroid() {
        super();
    }

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

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

        try {
          DiskFileItemFactory factory = new DiskFileItemFactory();
          ServletFileUpload upload = new ServletFileUpload(factory);
          List<FileItem> list = upload.parseRequest(request);
          System.out.println(list + " list " + list.size() );
          for(FileItem item : list) {
              String paramName = item.getFieldName();
              System.out.println(paramName);
              String paramValue = item.getString();
              System.out.println(paramValue);
              if(item.isFormField() == false) {
                  File f = new File("f:\\img.jpg");
                  item.write(f);
                   System.out.println("write filt success");
              }
          }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}