Android分别使用HTTP协议和TCP协议实现上传文件

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;@Overridepublic void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}@Overridepublic 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"));}}}