Android判斷網絡連接狀態并自動界面跳轉

用于判斷軟件打開時的網絡連接狀態，若無網絡連接，提醒用戶跳轉到設置界面

    /**


     * 設置在onStart()方法里面，可以在界面每次獲得焦點的時候都進行檢測 
     */  

    @Override  
    protected void onStart() {  
        ConnectivityManager manager = (ConnectivityManager) this  
                .getSystemService(Context.CONNECTIVITY_SERVICE);  
        NetworkInfo info = manager.getActiveNetworkInfo();  
        if (info != null && info.isConnected()) {  
            Toast.makeText(MainActivity.this, "網絡連接連接", 0).show();  
        } else {  
            AlertDialog.Builder builder = new Builder(MainActivity.this);  
            builder.setTitle("開啟網絡服務");  
            builder.setMessage("網絡沒有連接，請到設置進行網絡設置！");  
            builder.setPositiveButton("確定",  
                    new DialogInterface.OnClickListener() {  
                        public void onClick(DialogInterface dialog, int which) {  
                            if (android.os.Build.VERSION.SDK_INT > 10) {  
                                // 3.0以上打開設置界面，也可以直接用ACTION_WIRELESS_SETTINGS打開到wifi界面  
                                startActivity(new Intent(  
                                        android.provider.Settings.ACTION_SETTINGS));  
                            } else {  
                                startActivity(new Intent(  
                                        android.provider.Settings.ACTION_WIRELESS_SETTINGS));  
                            }  
                            dialog.cancel();  
                        }  
                    });  

            builder.setNegativeButton("取消",  
                    new DialogInterface.OnClickListener() {  
                        @Override  
                        public void onClick(DialogInterface dialog, int which) {  
                            dialog.cancel();  
                        }  
                    });  
            builder.show();  
        }  
        super.onStart();  
    }  </pre> 


 需要注冊的權限  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>