How to Use HttpURLConnection in Android to implement get post json data and download images

How to Use HttpURLConnection in Android to implement get post json data and download images

Use HttpURLConnection in Android to implement get post json data and download images

All Apache HTTP Client packages and classes are marked as deprecated in Android6.0.

All HTTP-related data request and submission operations are implemented through the HttpURLConnection class. The reality is that

Many Android Developers always use Apache HTTP Client as the andoird Client and the number of backend HTTP Interfaces

According to the interaction, I just used HttpURLConnection as an android APP, accidentally stepping on several

In summary, the most common method is to use HttpURLConnection to post json data and GET requests.

JSON data. In addition, you can download images in two ways: display progress and no display progress. Submit

When data involves Chinese characters, you must first transcode Chinese to UTF-8 and then submit the data in POST. Otherwise, you will always encounter

HTTP 400 error.

 

I. Example of GET request JSON data

public UserDto execute(String... params) {InputStream inputStream = null;HttpURLConnection urlConnection = null;try {// read responseURLEncoder.encode(para, "GBK");String urlWithParams = DOMAIN_ADDRESS + MEMBER_REQUEST_TOKEN_URL + "?userName=" + java.net.URLEncoder.encode(params[0],"utf-8") + "&password=" + params[1];URL url = new URL(urlWithParams);urlConnection = (HttpURLConnection) url.openConnection();/* optional request header */urlConnection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");/* optional request header */urlConnection.setRequestProperty("Accept", "application/json");/* for Get request */urlConnection.setRequestMethod("GET");int statusCode = urlConnection.getResponseCode();/* 200 represents HTTP OK */if (statusCode == 200) {inputStream = new BufferedInputStream(urlConnection.getInputStream());String response = HttpUtil.convertInputStreamToString(inputStream);Gson gson = new Gson();UserDto dto = gson.fromJson(response, UserDto.class);if (dto != null && dto.getToken() != null) {Log.i("token", "find the token = " + dto.getToken());}return dto;}} catch (Exception e) {e.printStackTrace();} finally {if (inputStream != null) {try {inputStream.close();} catch (IOException e) {e.printStackTrace();}}if (urlConnection != null) {urlConnection.disconnect();}}return null;}

Ii. Submit JSON data using POST

 

public Map
 
   execute(NotificationDto dto) {InputStream inputStream = null;HttpURLConnection urlConnection = null;try {URL url = new URL(getUrl);urlConnection = (HttpURLConnection) url.openConnection();/* optional request header */urlConnection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");/* optional request header */urlConnection.setRequestProperty("Accept", "application/json");dto.setCreator(java.net.URLEncoder.encode(dto.getCreator(), "utf-8"));// read response/* for Get request */urlConnection.setRequestMethod("POST");urlConnection.setDoOutput(true);DataOutputStream wr = new DataOutputStream(urlConnection.getOutputStream());Gson gson = new Gson();String jsonString = gson.toJson(dto);wr.writeBytes(jsonString);wr.flush();wr.close();// try to get responseint statusCode = urlConnection.getResponseCode();if (statusCode == 200) {inputStream = new BufferedInputStream(urlConnection.getInputStream());String response = HttpUtil.convertInputStreamToString(inputStream);Map
  
    resultMap = gson.fromJson(response, Map.class);if (resultMap != null && resultMap.size() > 0) {Log.i("applyDesigner", "please check the map with key");}return resultMap;}}catch(Exception e){e.printStackTrace();}finally{if (inputStream != null) {try {inputStream.close();} catch (IOException e) {e.printStackTrace();}}if (urlConnection != null) {urlConnection.disconnect();}}return null;}
  
 

Iii. Show the download progress

package com.example.demo;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.os.Handler;import android.os.Message;import android.util.Log;public class ImageLoadTask extends AsyncTask
 
   {private Handler handler;public ImageLoadTask(Handler handler) {this.handler = handler;}protected void onPostExecute(Bitmap result) {Message msg = new Message();msg.obj = result;handler.sendMessage(msg);}protected Bitmap doInBackground(String... getUrls) {InputStream inputStream = null;HttpURLConnection urlConnection = null;try {// open connectionURL url = new URL(getUrls[0]);urlConnection = (HttpURLConnection) url.openConnection();/* for Get request */urlConnection.setRequestMethod("GET");int fileLength = urlConnection.getContentLength();int statusCode = urlConnection.getResponseCode();if (statusCode == 200) {inputStream = urlConnection.getInputStream();byte data[] = new byte[4096];long total = 0;int count;ByteArrayOutputStream output = new ByteArrayOutputStream();while ((count = inputStream.read(data)) != -1) {total += count;// publishing the progress....if (fileLength > 0 && handler != null) {handler.sendEmptyMessage(((int) (total * 100 / fileLength)) - 1);}output.write(data, 0, count);}ByteArrayInputStream bufferInput = new ByteArrayInputStream(output.toByteArray());Bitmap bitmap = BitmapFactory.decodeStream(bufferInput);inputStream.close();bufferInput.close();output.close();Log.i("image", "already get the image by uuid : " + getUrls[0]);handler.sendEmptyMessage(100);return bitmap;}} catch (Exception e) {e.printStackTrace();} finally {if (inputStream != null) {try {inputStream.close();} catch (IOException e) {e.printStackTrace();}}if (urlConnection != null) {urlConnection.disconnect();}}return null;}}
 

Summary:The encoding method for submitting JSON data using HttpURLConnection is UTF-8

All Chinese characters must be pre-transcoded as UTF-8, and then in the background server corresponding API

Or the HTTP 400 error will be reported.