Android判断app当前是否联网

ConnectivityManager manager;

/**
* 检测网络是否连接
* @return
*/
private boolean checkNetworkState() {
boolean flag = false;
//得到网络连接信息
manager=(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
//去进行判断网络是否连接
if (manager.getActiveNetworkInfo() != null) {
flag = manager.getActiveNetworkInfo().isAvailable();
}
if (!flag) {
setNetwork();
} else {
isNetworkAvailable();
}

    return flag;  
}  


/** 
 * 网络未连接时，调用设置方法 
 */  
private void setNetwork(){  
    Toast.makeText(this, "wifi is closed!", Toast.LENGTH_SHORT).show();  

    AlertDialog.Builder builder = new AlertDialog.Builder(this);  
    builder.setIcon(R.drawable.ic_launcher);  
    builder.setTitle("网络提示信息");  
    builder.setMessage("网络不可用，如果继续，请先设置网络！");  
    builder.setPositiveButton("设置", new OnClickListener() {  
        @Override  
        public void onClick(DialogInterface dialog, int which) {  
            Intent intent = null;  
            /** 
             * 判断手机系统的版本！如果API大于10 就是3.0+ 
             * 因为3.0以上的版本的设置和3.0以下的设置不一样，调用的方法不同 
             */  
            if (android.os.Build.VERSION.SDK_INT > 10) {  
                intent = new Intent(android.provider.Settings.ACTION_WIFI_SETTINGS);  
            } else {  
                intent = new Intent();  
                ComponentName component = new ComponentName(  
                        "com.android.settings",  
                        "com.android.settings.WirelessSettings");  
                intent.setComponent(component);  
                intent.setAction("android.intent.action.VIEW");  
            }  
            startActivity(intent);  
        }  
    });  

    builder.setNegativeButton("取消", new OnClickListener() {  
        @Override  
        public void onClick(DialogInterface dialog, int which) {  

        }  
    });  
    builder.create();  
    builder.show();  
}  

/** 
 * 网络已经连接，然后去判断是wifi连接还是GPRS连接 
 * 设置一些自己的逻辑调用 
 */  
private void isNetworkAvailable(){  

    State gprs = manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();  
    State wifi = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();  
    if(gprs == State.CONNECTED || gprs == State.CONNECTING){  
        Toast.makeText(this, "wifi is open! gprs", Toast.LENGTH_SHORT).show();  
    }  
    //判断为wifi状态下才加载广告，如果是GPRS手机网络则不加载！  
    if(wifi == State.CONNECTED || wifi == State.CONNECTING){  
        Toast.makeText(this, "wifi is open! wifi", Toast.LENGTH_SHORT).show();  
        loadAdmob();  
    }  

}  

/** 
 * 在wifi状态下 加载admob广告 
 */  
private void loadAdmob(){  
    ll = (LinearLayout) findViewById(R.id.load_ads);  
    ll.removeAllViews();  
    adsView = new AdView(this, AdSize.BANNER, "a15194a1ac9505d");  
    ll.addView(adsView);  

    adsView.loadAd(new AdRequest());  
}