Question

我正在尝试编写可以读取JSONArray的代码，但是互联网服务器可能已关闭，设备无法连接，或者设备上没有互联网连接。

如何优雅地响应用户，因为我的异常catch块中的return语句似乎不起作用。

这是我的代码。

public JSONArray getJSONFromUrl(String url) {

    JSONArray jArray = null;

    // Making HTTP request
    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        if(httpResponse.getStatusLine().getStatusCode() == 200){
            // Connection was established. Get the content. 
            HttpEntity httpEntity = httpResponse.getEntity();

            // A Simple JSON Response Read
            istream = httpEntity.getContent();
        } else {
            throw new RuntimeException("Failed : HTTP error code : "
                   + httpResponse.getStatusLine().getStatusCode());
        }

        if(BuildConfig.DEBUG){
            Log.d(Constants.LOG, "httpEntity : ");
        }

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
        return;
    } catch (ClientProtocolException e) {
        e.printStackTrace();
        return;
    } catch (IOException e) {
        e.printStackTrace();
        return;
    }

Answer 1

只需使用Toast说出问题所在。例如“无法建立连接”

Answer 2

我是这样做的：

    ConnectivityManager cm = (ConnectivityManager)this.getSystemService(CONNECTIVITY_SERVICE);
    NetworkInfo ni =cm.getActiveNetworkInfo(); 
        if(ni==null){
final Dialog dialog = new Dialog(MainActivity.this);
            dialog.setContentView(R.layout.dialog);
            dialog.setTitle("No Internet Connection");
            dialog.show();
            dialog.setCancelable(false);
            Button settings = (Button) dialog.findViewById(R.id.settings);
            Button exit = (Button) dialog.findViewById(R.id.exitApp);
            Button retry = (Button) dialog.findViewById(R.id.retry);
            settings.setOnClickListener(new OnClickListener(){

                @Override
                public void onClick(View arg0) {
                    startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
                }

            });
            exit.setOnClickListener(new OnClickListener(){

                @Override
                public void onClick(View arg0) {
                dialog.cancel();    
                MainActivity.this.finish();
                }

            });
            retry.setOnClickListener(new OnClickListener(){

                @Override
                public void onClick(View arg0) {
                dialog.cancel();    
                MainActivity.this.finish();
                Intent newActivity = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(newActivity);
                }

            });

Answer 3

如果你有

，捕获量将如何发挥作用

throw new RuntimeException("Failed : HTTP error code : "
               + httpResponse.getStatusLine().getStatusCode());

如果你的代码告诉操作系统抛出它会抛出，你还能指望什么呢？

如果我没有互联网连接，我该如何回复用户？

3 个答案: