代码如下：

// 运用第三方jar包HttpClient进行上传
private void uploadHttpClient() {
   HttpClient client = new DefaultHttpClient();
   HttpPost post = new HttpPost(url);
   MultipartEntity muti = new MultipartEntity();
   File parent = Environment.getExternalStorageDirectory();
   File fileAbs = new File(parent, "one.png");
   
   FileBody fileBody = new FileBody(fileAbs);
   muti.addPart("file", fileBody);
   post.setEntity(muti);
   try {
       HttpResponse response = client.execute(post);
       if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
           System.out.println(EntityUtils.toString(response.getEntity()));
       }
   } catch (IOException e) {
       e.printStackTrace();
   }
}

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public class UploadActivity extends AppCompatActivity {
   private Button mButton;

   @Override
   protected void onCreate(@Nullable Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.upload);
       
       mButton = (Button) findViewById(R.id.btn);
       mButton.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View view) {
               File file = Environment.getExternalStorageDirectory();
               File fileAbs = new File(file,"one.png");
               
               String fileName=fileAbs.getAbsolutePath();
               String url = "http://192.168.23.4:8080/Upload";
               UploadThread thread = new UploadThread(fileName,url);
               thread.start();
           }
       });
   }
}