许多联网应用都在开始运行的时候检查当前网络状态，如果没有开启则去开启它，记录一下以前写程序时的网络检查，发现人的记忆力真是有限，总是隔段时间久忘记，所以记录下来是最好的记忆。

　　我们可以在一开始启动程序的时候检查网络连接状况，如果没有开启则弹出对话框设置网络

　　首先需要加入权限

检查网络状态代码如下

public boolean CheckNetworkState()     {
   boolean flag = false;         ConnectivityManager manager = (ConnectivityManager)getSystemService(                 Context.CONNECTIVITY_SERVICE); if(manager.getActiveNetworkInfo() != null)         {
               flag = manager.getActiveNetworkInfo().isAvailable();         } if(!flag)         {
               AlertDialog.Builder builder = new AlertDialog.Builder(this);             builder.setIcon(android.R.drawable.ic_dialog_alert);             builder.setTitle(R.string.netstate);             builder.setMessage(R.string.setnetwork);             builder.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {
                   @Override public void onClick(DialogInterface dialog, int which) {
   // TODO Auto-generated method stub                     Intent mIntent = new Intent("/");                     ComponentName comp = new ComponentName("com.android.settings",                             "com.android.settings.WirelessSettings");                     mIntent.setComponent(comp);                     mIntent.setAction("android.intent.action.VIEW");                     startActivity(mIntent);                 }             });             builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
                   @Override public void onClick(DialogInterface dialog, int which) {
                       dialog.cancel();                 }             });             builder.create();             builder.show();         } return flag;     }

效果如下，用户可以点击确定来设置网络，比如启动wifi

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如果希望网络连接时做一些事情的话，需要判断当前网络状态是否为true，为真则进行一些操作，否则设置网络。还可以用另外一种方式，其实差不多

//setnetwork     public void setNetwork()     {
           AlertDialog.Builder builder = new AlertDialog.Builder(this);         builder.setIcon(android.R.drawable.ic_dialog_alert);         builder.setTitle(R.string.netstate);         builder.setMessage(R.string.setnetwork);         builder.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {
               @Override public void onClick(DialogInterface dialog, int which) {
   // TODO Auto-generated method stub                 Intent mIntent = new Intent("/");                 ComponentName comp = new ComponentName("com.android.settings",                         "com.android.settings.WirelessSettings");                 mIntent.setComponent(comp);                 mIntent.setAction("android.intent.action.VIEW");                 startActivity(mIntent);             }         });         builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
               @Override public void onClick(DialogInterface dialog, int which) {
                   dialog.cancel();             }         });         builder.create();         builder.show();     } //NETWORK     public boolean isNetworkAvailable()     {
           Context context = getApplicationContext();         ConnectivityManager connect = (ConnectivityManager)context.getSystemService(                 Context.CONNECTIVITY_SERVICE); if(connect==null)         {
   return false;         }else//get all network info         {
               NetworkInfo[] info = connect.getAllNetworkInfo(); if(info!=null)             {
   for(int i=0;i

然后通过判断如果当前状态可用则执行相关代码，不可用则设置网络

if(isNetworkAvailable()) {
   相关代码 }else {
   setNetwork(); }