Android编程使用HTTP协议与TCP协议实现上传文件的方法

本文实例讲述了Android编程使用HTTP协议与TCP协议实现上传文件的方法。分享给大家供大家参考，具体如下：

Android上传文件有两种方式，第一种是基于Http协议的HttpURLConnection，第二种是基于TCP协议的Socket。 这两种方式的区别是使用HttpURLConnection上传时内部有缓存机制，如果上传较大文件会导致内存溢出。如果用TCP协议Socket方式上传就会解决这种弊端。

HTTP协议HttpURLConnection

1. 通过URL封装路径打开一个HttpURLConnection
2.设置请求方式以及头字段：Content-Type、Content-Length、Host
3.拼接数据发送

示例：

private static final String BOUNDARY = "---------------------------7db1c523809b2";//数据分割线
public boolean uploadHttpURLConnection(String username, String password, String path) throws Exception {
 //找到sdcard上的文件
 File file = new File(Environment.getExternalStorageDirectory(), path);
 //仿Http协议发送数据方式进行拼接
 StringBuilder sb = new StringBuilder();
 sb.append("--" + BOUNDARY + "\r\n");
 sb.append("Content-Disposition: form-data; name=\"username\"" + "\r\n");
 sb.append("\r\n");
 sb.append(username + "\r\n");
 sb.append("--" + BOUNDARY + "\r\n");
 sb.append("Content-Disposition: form-data; name=\"password\"" + "\r\n");
 sb.append("\r\n");
 sb.append(password + "\r\n");
 sb.append("--" + BOUNDARY + "\r\n");
 sb.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + path + "\"" + "\r\n");
 sb.append("Content-Type: image/pjpeg" + "\r\n");
 sb.append("\r\n");
 byte[] before = sb.toString().getBytes("UTF-8");
 byte[] after = ("\r\n--" + BOUNDARY + "--\r\n").getBytes("UTF-8");
 URL url = new URL("http://192.168.1.16:8080/14_Web/servlet/LoginServlet");
 HttpURLConnection conn = (HttpURLConnection) url.openConnection();
 conn.setRequestMethod("POST");
 conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);
 conn.setRequestProperty("Content-Length", String.valueOf(before.length + file.length() + after.length));
 conn.setRequestProperty("HOST", "192.168.1.16:8080");
 conn.setDoOutput(true);
 OutputStream out = conn.getOutputStream();
 InputStream in = new FileInputStream(file);
 out.write(before);
 byte[] buf = new byte[1024];
 int len;
 while ((len = in.read(buf)) != -1)
   out.write(buf, 0, len);
 out.write(after);
 in.close();
 out.close();
 return conn.getResponseCode() == 200;
}

TCP协议Socket

1.我们可以使用Socket发送TCP请求，将上传数据分段发送

示例：

public boolean uploadBySocket(String username, String password, String path) throws Exception {
 // 根据path找到SDCard中的文件
 File file = new File(Environment.getExternalStorageDirectory(), path);
 // 组装表单字段和文件之前的数据
 StringBuilder sb = new StringBuilder();
 sb.append("--" + BOUNDARY + "\r\n");
 sb.append("Content-Disposition: form-data; name=\"username\"" + "\r\n");
 sb.append("\r\n");
 sb.append(username + "\r\n");
 sb.append("--" + BOUNDARY + "\r\n");
 sb.append("Content-Disposition: form-data; name=\"password\"" + "\r\n");
 sb.append("\r\n");
 sb.append(password + "\r\n");
 sb.append("--" + BOUNDARY + "\r\n");
 sb.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + path + "\"" + "\r\n");
 sb.append("Content-Type: image/pjpeg" + "\r\n");
 sb.append("\r\n");
 // 文件之前的数据
 byte[] before = sb.toString().getBytes("UTF-8");
 // 文件之后的数据
 byte[] after = ("\r\n--" + BOUNDARY + "--\r\n").getBytes("UTF-8");
 URL url = new URL("http://192.168.1.199:8080/14_Web/servlet/LoginServlet");
 // 由于HttpURLConnection中会缓存数据, 上传较大文件时会导致内存溢出, 所以我们使用Socket传输
 Socket socket = new Socket(url.getHost(), url.getPort());
 OutputStream out = socket.getOutputStream();
 PrintStream ps = new PrintStream(out, true, "UTF-8");
 // 写出请求头
 ps.println("POST /14_Web/servlet/LoginServlet HTTP/1.1");
 ps.println("Content-Type: multipart/form-data; boundary=" + BOUNDARY);
 ps.println("Content-Length: " + String.valueOf(before.length + file.length() + after.length));
 ps.println("Host: 192.168.1.199:8080");
 InputStream in = new FileInputStream(file);
 // 写出数据
 out.write(before);
 byte[] buf = new byte[1024];
 int len;
 while ((len = in.read(buf)) != -1)
   out.write(buf, 0, len);
 out.write(after);
 in.close();
 out.close();
 return true;
}

搭建服务器，完成上传功能

package cn.test.web.servlet;
import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class LoginServlet extends HttpServlet {
 private static final long serialVersionUID = 1L;
 @Override
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   doPost(request, response);
 }
 @Override
 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   boolean isMultipart = ServletFileUpload.isMultipartContent(request);
   if (isMultipart)
     try {
       FileItemFactory factory = new DiskFileItemFactory();
       ServletFileUpload upload = new ServletFileUpload(factory);
       List<FileItem> items = upload.parseRequest(request);
       File dir = new File(request.getSession().getServletContext().getRealPath("/WEB-INF/upload"));
       //创建目录
       dir.mkdir();
       for (FileItem item : items)
         if (item.isFormField())
           System.out.println(item.getFieldName() + ": " + item.getString());
         else{
           item.write(new File(dir,item.getName().substring(item.getName().lastIndexOf("\\")+1)));
         }
     } catch (Exception e) {
       e.printStackTrace();
     }
   else {
     System.out.println(request.getMethod());
     System.out.println(request.getParameter("username"));
     System.out.println(request.getParameter("password"));
   }
 }
}

希望本文所述对大家Android程序设计有所帮助。