为什么百度apistore的天气api在Java项目中能用而在安卓项目中不能用？

百度apistore的天气api

String httpArg = "city=beijing";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    String httpUrl = "http://apis.baidu.com/heweather/weather/free";
    String httpArg = "city=beijing";
    BufferedReader reader = null;
    String result = null;
    StringBuffer sbf = new StringBuffer();
    httpUrl = httpUrl + "?" + httpArg;

    try {
        URL url = new URL(httpUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("apikey","f1375c3a44007cdc331966524783f3ab");
        connection.connect();
        InputStream is = connection.getInputStream();
        reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
        String strRead = null;
        while ((strRead = reader.readLine()) != null) {
            sbf.append(strRead);
            sbf.append("\r\n");
        }
        reader.close();
        result = sbf.toString();
    } catch (Exception e) {
        e.printStackTrace();
    }

    Log.d("tag",result+"-------");
}`

就这个，在安卓中返回null。
在Java项目中返回正常

---

尝试在安卓浏览器里面访问这个api

---

经测试，在Android中也可以正常获取到数据。

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        new Thread(){
            @Override
            public void run() {
                // TODO Auto-generated method stub
                String httpUrl = "http://apis.baidu.com/heweather/weather/free";
                String httpArg = "city=beijing";
                BufferedReader reader = null;
                String result = null;
                StringBuffer sbf = new StringBuffer();
                httpUrl = httpUrl + "?" + httpArg;

                try {
                    URL url = new URL(httpUrl);
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setRequestProperty("apikey","f1375c3a44007cdc331966524783f3ab");
                    connection.connect();
                    InputStream is = connection.getInputStream();
                    reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
                    String strRead = null;
                    while ((strRead = reader.readLine()) != null) {
                        sbf.append(strRead);
                        sbf.append("\r\n");
                    }
                    reader.close();
                    result = sbf.toString();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                Log.d("tag",result+"-------");            
                super.run();
            }            
        }.start();
        
    }

Android中获取网络数据需要新开线程，另外还需要在Manifest中添加权限。