public class MainActivity extends AppCompatActivity {  private String Path = "https://10.url.cn/eth/ajNVdqHZLLAxibwnrOxXSzIxA76ichutwMCcOpA45xjiapneMZsib7eY4wUxF6XDmL2FmZEVYsf86iaw/";  private static final int SUCCESS = 993;  private static final int FALL = 814;  Handler handler = new Handler() {    @Override    public void handleMessage(Message msg) {      switch (msg.what) {        //加載網絡成功,進行UI的更新,處理得到的圖片資源        case SUCCESS:          //通過message,拿到字節數組          byte[] Picture = (byte[]) msg.obj;          //使用BitmapFactory工廠,把字節數組轉換為bitmap          Bitmap bitmap = BitmapFactory.decodeByteArray(Picture, 0, Picture.length);          //通過ImageView,設置圖片          mImageView_okhttp.setImageBitmap(bitmap);          break;        //當加載網絡失敗,執行的邏輯代碼        case FALL:          Toast.makeText(MainActivity.this, "網絡異常", Toast.LENGTH_SHORT).show();          break;        default:          break;      }    }  };  private ImageView mImageView_okhttp;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //初始化控件    initView();  }  private void initView() {    mImageView_okhttp = (ImageView) findViewById(R.id.imageView_okhttp);  }  /**   * 根據點擊事件獲取絡上的圖片資源,使用的是OKhttp框架   *   * @param view   */  public void Picture_okhttp_bt(View view) {    //1. 創建OKhttpClient對象    OkHttpClient okHttpClient = new OkHttpClient();    //2.建立Request對象,設置參數,請求方式如果是get,就不用設置,默認使用的就是get    Request request = new Request.Builder()        .url(Path)//設置請求網址        .build();//建立request對象    //3.創建一個Call對象,參數是request對象,發送請求    Call call = okHttpClient.newCall(request);    //4.異步請求,請求加入調度    call.enqueue(new Callback() {      @Override//請求失敗回調      public void onFailure(Call call, IOException e) {        handler.sendEmptyMessage(FALL);      }      @Override//請求成功回調      public void onResponse(Call call, Response response) throws IOException {        //得到從網上獲取資源,轉換成我們想要的類型        byte[] Picture_bt = response.body().bytes();        //通過handler更新UI        Message message = handler.obtainMessage();        message.obj = Picture_bt;        message.what = SUCCESS;        handler.sendMessage(message);      }    });  }  //當按鈕點擊時,執行使用OKhttp上傳圖片到服務器(http://blog.csdn.net/tangxl2008008/article/details/51777355)  //注意:有時候上傳圖片失敗,是服務器規定還要上傳一個Key,如果開發中關于網絡這一塊出現問題,就多和面試官溝通溝通  public void uploading(View view) {    //圖片上傳接口地址    String url = "https://www.718shop.com/sell/sell.m.picture.upload.do";    //創建上傳文件對象    File file = new File(Environment.getExternalStorageDirectory(), "big.jpg");    //創建RequestBody封裝參數    RequestBody fileBody = RequestBody.create(MediaType.parse("application/octet-stream"), file);    //創建MultipartBody,給RequestBody進行設置    MultipartBody multipartBody = new MultipartBody.Builder()        .setType(MultipartBody.FORM)        .addFormDataPart("image", "big.jpg", fileBody)        .build();    //創建Request    Request request = new Request.Builder()        .url(url)        .post(multipartBody)        .build();    //創建okhttp對象    OkHttpClient okHttpClient = new OkHttpClient.Builder()        .connectTimeout(10, TimeUnit.SECONDS)        .readTimeout(10, TimeUnit.SECONDS)        .writeTimeout(10, TimeUnit.SECONDS)        .build();    //上傳完圖片,得到服務器反饋數據    okHttpClient.newCall(request).enqueue(new Callback() {      @Override      public void onFailure(Call call, IOException e) {        Log.e("ff", "uploadMultiFile() e=" + e);      }      @Override      public void onResponse(Call call, Response response) throws IOException {        Log.i("ff", "uploadMultiFile() response=" + response.body().string());      }    });  }}

<RelativeLayout  xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  tools:context="com.sn.picture_okhttp.MainActivity">  <Button    android:id="@+id/button"    android:onClick="Picture_okhttp_bt"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="下載圖片"    android:layout_alignParentTop="true"    android:layout_centerHorizontal="true"    android:layout_marginTop="59dp"/>  <Button    android:text="上傳圖片"    android:onClick="uploading"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:id="@+id/button2"    android:layout_alignParentTop="true"    android:layout_alignLeft="@+id/button"    android:layout_alignStart="@+id/button"/>  <ImageView    android:id="@+id/imageView_okhttp"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_alignParentBottom="true"    android:layout_centerHorizontal="true"/></RelativeLayout>

implementation 'com.squareup.okhttp3:okhttp:3.4.2'