Android中使用HttpURLConnection实现GET POST JSON数据与下载图片

Android6.0中把Apache HTTP Client所有的包与类都标记为deprecated不再建议使用

所有跟HTTP相关的数据请求与提交操作都通过HttpURLConnection类实现，现实是

很多Android开发者一直都Apache HTTP Client来做andoird客户端与后台HTTP接口数

据交互，本人刚刚用HttpURLConnection做了一个android的APP，不小心踩到了几个

坑，总结下最常用的就通过HttpURLConnection来POST提交JSON数据与GET请求

JSON数据。此外就是下载图片，下载图片分为显示进度与不显示进度两种。其中提交

数据的时候涉及中文一定要先把中文转码成utf-8之后在POST提交，否则就会一直遇到

HTTP 400的错误。

一：GET请求JSON数据的例子

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;}

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 response		int 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;}
     
    

三：下载图片显示下载进度

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 connection			URL 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;	}}
    

所有中文字符请一定要预先转码为UTF-8，然后在后台服务器对应的API

中解码为UTF-8，不然就会报错HTTP 400。