//非同步任務處理
    //建立內部類,來實現網路非同步請求
    //新建內部類 繼承 AsyncTask
    @SuppressLint("StaticFieldLeak")
    class RequestNetworkDataTask extends AsyncTask<String,Integer,String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            textView.setText("載入中");
            //主執行緒
        }

        @Override
        protected String doInBackground(String[] strings) {
            String result = requestData(strings[0]);
            return result;
            //子執行緒,需要非同步執行的命令在此執行
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            textView.setText(s);
            //主執行緒
            //非同步程式碼處理完後,在主執行緒中進行進一步操作
        }
    }
 

在需要呼叫這個自定義內部類的地方使用以下程式碼

                String url = getEditTextUrl();
                new RequestNetworkDataTask().execute(url);

下面是通過EditText 獲取輸入的網址

通過點選Button 在下方的TextView中顯示網址對應的網站原始碼

public class NetworkActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText editText;
    private Button btn;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_network);
        initView();
        btn.setOnClickListener(this);
    }

    private void initView() {
        editText = findViewById(R.id.act_network_url_et);
        btn = findViewById(R.id.act_network_getNet_btn);
        textView = findViewById(R.id.act_network_show_tv);

    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.act_network_getNet_btn:
                String url = getEditTextUrl();
                new RequestNetworkDataTask().execute(url);
                break;
        }
    }

    private String getEditTextUrl() {
        return editText != null ? editText.getText().toString() : "";

    }

    private String requestData(String urlString) {
        try {
            URL url = new URL(urlString);
            //開啟Url
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            //設定超時時間
            connection.setConnectTimeout(5000);
            //設定請求方法
            connection.setRequestMethod("GET");
            //開始請求
            connection.connect();
            int response = connection.getResponseCode();
            //請求的訊息
            String reponseMessage = connection.getResponseMessage();

            InputStream inputStream = connection.getInputStream();

            Reader reader = new InputStreamReader(inputStream, "UTF-8");
            char[] buffer = new char[1024 * 8];
            reader.read(buffer);
            String content = new String(buffer);
            return content;
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    //非同步任務處理
    //建立內部類,來實現網路非同步請求
    @SuppressLint("StaticFieldLeak")
    class RequestNetworkDataTask extends AsyncTask<String,Integer,String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            textView.setText("載入中");
            //主執行緒
        }

        @Override
        protected String doInBackground(String[] strings) {
            String result = requestData(strings[0]);
            return result;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            textView.setText(s);
            //主執行緒
        }
    }
}