[Android]取得wifi IP

利用WifiManager取得IP

AndroidManifest.xml需要加入
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="johnson.layout"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
	<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".Layout_testActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

Java部份：

import android.app.Activity;
import android.net.wifi.WifiManager;
import android.net.wifi.WifiInfo;
import android.os.Bundle;
import android.widget.TextView;

public class test extends Activity {
	TextView ans = null;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        ans = (TextView) findViewById( R.id.ans );
        ans.setText("IP：" + getMyIp() );
    }
	
	//取得IP
	private String getMyIp(){
        //新增一個WifiManager物件並取得WIFI_SERVICE
		WifiManager wifi_service = (WifiManager)getSystemService(WIFI_SERVICE);
		//取得wifi資訊
		WifiInfo wifiInfo = wifi_service.getConnectionInfo();
		//取得IP，但這會是一個詭異的數字，還要再自己換算才行
		int ipAddress = wifiInfo.getIpAddress();
		//利用位移運算和AND運算計算IP
		String ip = String.format("%d.%d.%d.%d",(ipAddress & 0xff),(ipAddress >> 8 & 0xff),(ipAddress >> 16 & 0xff),(ipAddress >> 24 & 0xff));
		return ip;	 
	}
}