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 + "rn"); sb.append("Content-Disposition: form-data; name="username"" + "rn"); sb.append("rn"); sb.append(username + "rn"); sb.append("--" + BOUNDARY + "rn"); sb.append("Content-Disposition: form-data; name="password"" + "rn"); sb.append("rn"); sb.append(password + "rn"); sb.append("--" + BOUNDARY + "rn"); sb.append("Content-Disposition: form-data; name="file"; filename="" + path + """ + "rn"); sb.append("Content-Type: image/pjpeg" + "rn"); sb.append("rn"); byte[] before = sb.toString().getBytes("UTF-8"); byte[] after = ("rn--" + BOUNDARY + "--rn").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 + "rn"); sb.append("Content-Disposition: form-data; name="username"" + "rn"); sb.append("rn"); sb.append(username + "rn"); sb.append("--" + BOUNDARY + "rn"); sb.append("Content-Disposition: form-data; name="password"" + "rn"); sb.append("rn"); sb.append(password + "rn"); sb.append("--" + BOUNDARY + "rn"); sb.append("Content-Disposition: form-data; name="file"; filename="" + path + """ + "rn"); sb.append("Content-Type: image/pjpeg" + "rn"); sb.append("rn"); // 文件之前的数据 byte[] before = sb.toString().getBytes("UTF-8"); // 文件之后的数据 byte[] after = ("rn--" + BOUNDARY + "--rn").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。
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