Android编程实现图片的上传和下载功能示例

File file = new File(imageUrl);
String httpUrl = httpDomain+"AddImageServlet"+"?gid="+gid;
HttpPost request = new HttpPost(httpUrl);
HttpClient httpClient = new DefaultHttpClient();
FileEntity entity = new FileEntity(file,"binary/octet-stream");
HttpResponse response;
try {
  request.setEntity(entity);
  entity.setContentEncoding("binary/octet-stream");
  response = httpClient.execute(request);
//如果返回状态为200，获得返回的结果
if(response.getStatusLine().getStatusCode()==HttpStatus.SC_OK){
……//图片上传成功
}
}
catch(Exception e){
}

//获得新闻id
String gid = request.getParameter("gid");
String filePath = getRealPath(request) + "\\userpic\\";
//   定义上载文件的最大字节
int MAX_SIZE = 102400 * 102400;
//   声明文件读入类
DataInputStream in = null;
FileOutputStream fileOut = null;
//   取得客户端上传的数据类型
String contentType = request.getContentType();
if(contentType.indexOf("binary/octet-stream") >= 0){
  //   读入上传的数据
  in = new DataInputStream(request.getInputStream());
  int formDataLength = request.getContentLength();
  // 如果图片过大
  if(formDataLength > MAX_SIZE){
    String errormsg=("上传的文件字节数不可以超过" + MAX_SIZE);
    out.println(errormsg);
    return ;
  }
//   保存上传文件的数据
byte dataBytes[] = new byte[formDataLength];
int byteRead = 0;
int totalBytesRead = 0;
//   上传的数据保存在byte数组
while(totalBytesRead < formDataLength){
byteRead = in.read(dataBytes,totalBytesRead,formDataLength);
totalBytesRead += byteRead;
 }
String fileName = filePath + gid+".png";
 //   检查上载文件的目录是否存在
File fileDir = new File(filePath);
if(!fileDir.exists()){
fileDir.mkdirs();
}
//   创建文件的写出类
fileOut = new FileOutputStream(fileName);
//   保存文件的数据
fileOut.write(dataBytes);
fileOut.close();
//保存文件的路径名
……

//获得网络中的图片
public Bitmap getGossipImage(String gid){
    String httpUrl = httpDomain+"userpic/"+gid+".png";
    Bitmap bitmap = null;
    HttpGet httpRequest = new HttpGet(httpUrl);
    //取得HttpClient 对象
    HttpClient httpclient = new DefaultHttpClient();
    try {
      //请求httpClient ，取得HttpRestponse
      HttpResponse httpResponse = httpclient.execute(httpRequest);
      if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
        //取得相关信息 取得HttpEntiy
        HttpEntity httpEntity = httpResponse.getEntity();
        InputStream is = httpEntity.getContent();
        bitmap = BitmapFactory.decodeStream(is);
        is.close();
      }else{
         Toast.makeText(context, "连接失败!", Toast.LENGTH_SHORT).show();
      }
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return bitmap;
}