访问网络

使用HttpURLConnection

1.申请权限

   

<uses-permission android:name="android.permission.INTERNET" />

2.按钮注册onclick()事件,执行方法

sendRequestWithHttpURLConnection();

3.在textView中显示获取的数据

private void sendRequestWithHttpURLConnection() {
    // 开启线程来发起网络请求
new Thread(new Runnable() {
        @Override
public void run() {
            HttpURLConnection connection = null;
            BufferedReader reader = null;
            try {
                URL url = new URL(https://www.baidu.com); //注意是https ,写http不能获取数据了
                connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");
                connection.setConnectTimeout(8000);
                connection.setReadTimeout(8000);
                InputStream in = connection.getInputStream();
                // 下面对获取到的输入流进行读取
reader = new BufferedReader(new InputStreamReader(in));
                final StringBuilder response = new StringBuilder();
                String line;
                while ((line = reader.readLine()) != null) {
                    response.append(line);
                    Log.w("myyyyyyyyyyyyy",response.toString());
                }
                runOnUiThread(new Runnable() {
                    @Override
public void run() {
                        textView.setText(response);
                    }
                });

            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (connection != null) {
                    connection.disconnect();
                }
            }
        }
    }).start();
}

使用OKHttp3

链接地址;http://blog.csdn.net/itachi85/article/details/51190687

OKHttp3的断点下载功能:

Request request = new Request.Builder()
        // 断点下载，指定从哪个字节开始下载
.addHeader("RANGE", "bytes=" + downloadedLength + "-")
        .url(downloadUrl)
        .build();

savedFile.seek(downloadedLength); // 跳过已下载的字节