判斷是否為閏年

1，php閏年計算方法一：

閏年是對4取餘為0，對100取餘不等於0，對400取餘等於0的年是閏年。

$day = date('Y');
if ($day%4==0&&($day%100!=0 || $day%400==0)){
    echo $day.'是閏年';
}else{
    echo $day.'不是閏年';
}

2，php判斷閏年 方法二：

date('L');就可以直接判斷當前年份是否是閏年，為真返回1，否則返回0.

$year = 2008;//可以像上例一樣用mt_rand隨機取一個年，也可以隨便賦值。
$time = mktime(20,20,20,4,20,$year);//取得一個日期的 Unix 時間戳;
if (date("L",$time)==1){ //格式化時間，並且判斷是不是閏年，後面的等於一也可以省略；
echo $year."是閏年";
}else{
echo $year."不是閏年";
}

3，php判斷閏年 計算閏年的方法三：

$year = 2000;
$time = mktime(20,20,20,2,1,$year);//取得一個日期的 Unix 時間戳;
if (date("t",$time)==29){ //格式化時間，並且判斷2月是否是29天；
echo $year."是閏年";//是29天就輸出時閏年；
}else{
echo $year."不是閏年";
}

以上就是php判斷是否為閏年的詳細內容 

資料來源: https://tw511.com/a/01/6176.html

Android Studio get device ip

 Get the device ip function

Append the permission for AndroidManifest.xml

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

Create an app with a button and a textview.

public class MainActivity extends AppCompatActivity {
    TextView txt_log;
    Button btn_get_ip;
    Button btn_ping_ip;
    Button btn_check_url_alive;
    Button btn_clean_log;
    String device_ip = "192.168.1.10";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //  Asign the items
        txt_log = findViewById(R.id.txt_log);
        btn_get_ip = findViewById(R.id.btn_get_ip);
        btn_ping_ip = findViewById(R.id.btn_ping_ip);
        btn_check_url_alive = findViewById(R.id.btn_check_url_alive);
        btn_clean_log = findViewById(R.id.btn_clean_log);

        //  Initial item
        txt_log.setMovementMethod(new ScrollingMovementMethod());

        //  Asign the click function of all items
        btn_get_ip.setOnClickListener(btn_get_ip_click);
        btn_ping_ip.setOnClickListener(btn_ping_ip_click);
        btn_check_url_alive.setOnClickListener(btn_check_url_alive_click);
        btn_clean_log.setOnClickListener(btn_clean_log_click);

        txt_log.append("App created\n");
    }
    private View.OnClickListener btn_get_ip_click = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            txt_log.append("btn_get_ip clicked\n");

            String ipAddress = wifiIpAddress(getApplicationContext());
            txt_log.append(ipAddress +"\n");
            device_ip = ipAddress;
            txt_log.append("Set device ip = " + ipAddress +"\n");

            int [] ipDot = getDetailsWifiInfo(getApplicationContext());
            device_ip = ipDot[0] +"."+ ipDot[1] +"."+ ipDot[2] +".245";
            txt_log.append("Set device ip = " + device_ip +"\n");
            //txt_log.append(ipDot[0] +"\n");
            //txt_log.append(ipDot[1] +"\n");
            //txt_log.append(ipDot[2] +"\n");
            //txt_log.append(ipDot[3] +"\n");
        }
    };

    private View.OnClickListener btn_ping_ip_click = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            txt_log.append("btn_ping_ip clicked\n");

            String ret = executeCmd("ping -c 1 -w 1 " + device_ip, false);
            txt_log.append(ret +"\n");
        }
    };

    private View.OnClickListener btn_check_url_alive_click = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            txt_log.append("btn_check_url_alive_click\n");

            int [] ipDot = getDetailsWifiInfo(getApplicationContext());
            for(int cnt =240; cnt < 246; cnt++){
                String url_link = "http://"+  ipDot[0] +"."+ ipDot[1] +"."+ ipDot[2] +"." + cnt +"/";
                //txt_log.append(url_link + "\n");
                new JsonTask().execute(url_link);
            }
        }
    };

    private View.OnClickListener btn_clean_log_click = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            txt_log.setText("");
        }
    };

    protected String wifiIpAddress(Context context) {
        WifiManager wifiManager = (WifiManager) context.getSystemService(WIFI_SERVICE);
        int ipAddress = wifiManager.getConnectionInfo().getIpAddress();
        //txt_log.append(String.valueOf(ipAddress) +"\n" );

        // Convert little-endian to big-endianif needed
        if (ByteOrder.nativeOrder().equals(ByteOrder.LITTLE_ENDIAN)) {
            ipAddress = Integer.reverseBytes(ipAddress);
            //txt_log.append(String.valueOf(ipAddress) +"\n" );
        }

        byte[] ipByteArray = BigInteger.valueOf(ipAddress).toByteArray();

        String ipAddressString;
        try {
            ipAddressString = InetAddress.getByAddress(ipByteArray).getHostAddress();
            //txt_log.append(ipAddressString +"\n" );
        } catch (UnknownHostException ex) {
            txt_log.append("WIFIIP Unable to get host address.");
            ipAddressString = null;
        }

        return ipAddressString;
    }

    private int [] getDetailsWifiInfo(Context mContext) {
        try {
            WifiManager wifiManager = (WifiManager) mContext.getSystemService(WIFI_SERVICE);
            WifiInfo mWifiInfo = wifiManager.getConnectionInfo();
            int ip = mWifiInfo.getIpAddress();

            int [] ret = new int[4];
            int ip_01 = (ip & 0xFF);
            int ip_02 = ((ip >> 8) & 0xFF);
            int ip_03 = ((ip >> 16) & 0xFF);
            int ip_04 = ((ip >> 24) & 0xFF);
            ret[0] = ip_01;
            ret[1] = ip_02;
            ret[2] = ip_03;
            ret[3] = ip_04;
            String strIp = "" + (ip_01) + "." + (ip_02) + "." + (ip_03) + "." + (ip_04);

            //txt_log.append(ip_01 +"\n");
            //txt_log.append(ip_02 +"\n");
            //txt_log.append(ip_03 +"\n");
            //txt_log.append(ip_04 +"\n");
            return ret;
        } catch (Exception e) {
            txt_log.append(e.toString() + "\n");
        }
        return null;
    }

    //

    public static String executeCmd(String cmd, boolean sudo){
        try {

            Process p;
            if(!sudo)
                p= Runtime.getRuntime().exec(cmd);
            else{
                p= Runtime.getRuntime().exec(new String[]{"su", "-c", cmd});
            }
            BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));

            String s;
            String res = "";
            while ((s = stdInput.readLine()) != null) {
                res += s + "\n";
            }
            p.destroy();
            return res;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";

    }

    public boolean exists(String URLName) {
        try {
            URL url = new URL("http://www.android.com/");
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            int responseCode = urlConnection.getResponseCode();
            txt_log.append("responseCode:" + responseCode +"\n");
            //InputStream in = new BufferedInputStream(urlConnection.getInputStream());
            //txt_log.append(in.toString() +"\n");
            //readStream(in);
            urlConnection.disconnect();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
        }

        try {
            HttpURLConnection.setFollowRedirects(false);
            // note : you may also need
            // HttpURLConnection.setInstanceFollowRedirects(false)
            HttpURLConnection con = (HttpURLConnection) new URL(URLName)
                    .openConnection();
            con.setRequestMethod("HEAD");
            return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }


    private class JsonTask extends AsyncTask<String, String, String> {
        ProgressDialog pd;
        HttpURLConnection connection = null;
        String url_link;
        protected void onPreExecute() {
            super.onPreExecute();

            pd = new ProgressDialog(MainActivity.this);
            pd.setMessage("Please wait");
            pd.setCancelable(false);
            pd.show();
        }

        protected String doInBackground(String... params) {
            BufferedReader reader = null;

            try {
                url_link = params[0];
                URL url = new URL(url_link);
                connection = (HttpURLConnection) url.openConnection();
                connection.setConnectTimeout(3000);
                connection.connect();


                InputStream stream = connection.getInputStream();

                reader = new BufferedReader(new InputStreamReader(stream));

                StringBuffer buffer = new StringBuffer();
                String line = "";

                while ((line = reader.readLine()) != null) {
                    buffer.append(line+"\n");
                    //Log.d("Response:", "> " + line + "\n");
                    //txt_log.append("Response: > " + line + "\n");   //here u ll get whole response...... :-)

                }
                return buffer.toString();


            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (reader != null) {
                        reader.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            if (pd.isShowing()){
                pd.dismiss();
            }
            try {
                Log.d("Response:", "> " + connection.getResponseCode() + "\n");
                txt_log.append(url_link +"->" + connection.getResponseCode() + "\n");
                if (connection != null) {
                    connection.disconnect();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            //txt_log.append(result + "\n");
        }
    }
}

Android WebView ERR_CLEARTEXT_NOT_PERMITTED

今天無意間用了小米9，測試了WebView打開的一些鏈接，在其他的手機上（系統8.0以下）都是正常可以打開鏈接。

然後定位到問題所在，記錄一下net::ERR_CLEARTEXT_NOT_PERMITTED的原因，如下：

從Android 9.0（API級別28）開始，默認情況下禁用明文支持。因此http的url均無法在webview中加載

附上我使用的解決辦法：

在manifest中application節點添加

android:usesCleartextTraffic="true"

1

添加後如下：

<?xml version="1.0" encoding="utf-8"?>

<manifest ...>

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

    <application

        ...

        android:usesCleartextTraffic="true"

        ...>

        ...

    </application>

</manifest>

附上鍊接：https://stackoverflow.com/questions/45940861/android-8-cleartext-http-traffic-not-permitted

同時如果你還有webView 的問題，我遇到並記錄的如下

net:err_unknown_url_scheme

android調用js方法

Android9.0_P:ClassNotFoundException:Didn't find class “org.apache.http.ProtocolVersion” on path:

以上是開發中遇到的問題，後期有時間還會繼續整理，或者您有更好的解決方法，添加更完善，不勝感激。歡迎留言交流，

書到用時方恨少，紙上得來終覺淺！共勉。

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版权声明：本文为CSDN博主「冷冷清清里风风火火是我」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。

原文链接：https://blog.csdn.net/qq_33721320/article/details/84400825 

How to create an empty DataFrame and append rows & columns to it in Pandas?

Let’s discuss how to create an empty DataFrame and append rows & columns to it in Pandas. There are multiple ways in which we can do this task.

Method #1: Create a complete empty DataFrame without any column name or indices and then appending columns one by one to it.

# import pandas library as pd import pandas as pd    # create an Empty DataFrame object df = pd.DataFrame()    print(df)    # append columns to an empty DataFrame df['Name'] = ['Ankit', 'Ankita', 'Yashvardhan'] df['Articles'] = [97, 600, 200] df['Improved'] = [2200, 75, 100]    df

Output:

Method #2: Create an empty DataFrame with columns name only then appending rows one by one to it using append() method.

# import pandas library as pd import pandas as pd    # create an Empty DataFrame # object With column names only df = pd.DataFrame(columns = ['Name', 'Articles', 'Improved']) print(df)    # append rows to an empty DataFrame df = df.append({'Name' : 'Ankit', 'Articles' : 97, 'Improved' : 2200},                  ignore_index = True) df = df.append({'Name' : 'Aishwary', 'Articles' : 30, 'Improved' : 50},                 ignore_index = True) df = df.append({'Name' : 'yash', 'Articles' : 17, 'Improved' : 220},                ignore_index = True)    df

Output:

Method #3: Create an empty DataFrame with a column name and indices and then appending rows one by one to it using loc[] method.

# import pandas library as pd import pandas as pd    # create an Empty DataFrame object With # column names and indices  df = pd.DataFrame(columns = ['Name', 'Articles', 'Improved'],                     index = ['a', 'b', 'c'])    print("Empty DataFrame With NaN values : \n\n", df)    # adding rows to an empty  # dataframe at existing index df.loc['a'] = ['Ankita', 50, 100] df.loc['b'] = ['Ankit', 60, 120] df.loc['c'] = ['Harsh', 30, 60]    df

Output:

資料來源: https://www.geeksforgeeks.org/how-to-create-an-empty-dataframe-and-append-rows-columns-to-it-in-pandas/