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。