android开发之欢迎界面的小例子

首先你得写好xml文件，这也是最主要的。

然后，在activity中加入一个线程，延时2秒，用来跳转到主界面。

activity中线程代码如下：(顺便检测一下网络是否打开）

[java]

@override
    protected void onstart() {
        super.onstart();
        if(<span style="color: #ff0000">isnetworkconnected()</span>){
            new thread(){
                @override
                public void run() {
                    try {
                        thread.sleep(2000);
                        intent intent = new intent(<span style="color: #ff0000">splashactivity.this</span>,<span style="color: #ff0000">compusassistmain.class</span>);
                        startactivity(intent);
                        finish();
                    } catch (interruptedexception e) {
                        e.printstacktrace();
                    }

                }
            }.start();
        }else{
            //弹出对话框 让用户设置网络 
            alertdialog.builder builder = new builder(this);
            builder.settitle("设置网络");
            builder.setmessage("网络错误请设置网络");
            builder.setpositivebutton("设置网络", new onclicklistener() {
                public void onclick(dialoginterface dialog, int which) {
                    intent intent = new intent();
                    intent.setclassname(<span style="color: #ff6666">"com.android.settings"</span>, <span style="color: #ff6666">"com.android.settings.wirelesssettings"</span>);
                    startactivity(intent);
                }
            });
            builder.setnegativebutton("取消", new onclicklistener() {

                public void onclick(dialoginterface dialog, int which) {
                    finish();
                }
            });
            builder.create().show();
        }
    }

@override
 protected void onstart() {
  super.onstart();
  if(isnetworkconnected()){
   new thread(){
    @override
    public void run() {
     try {
      thread.sleep(2000);
      intent intent = new intent(splashactivity.this,compusassistmain.class);
      startactivity(intent);
      finish();
     } catch (interruptedexception e) {
      e.printstacktrace();
     }

    }
   }.start();
  }else{
   //弹出对话框 让用户设置网络
   alertdialog.builder builder = new builder(this);
   builder.settitle("设置网络");
   builder.setmessage("网络错误请设置网络");
   builder.setpositivebutton("设置网络", new onclicklistener() {
    public void onclick(dialoginterface dialog, int which) {
     intent intent = new intent();
     intent.setclassname("com.android.settings", "com.android.settings.wirelesssettings");
     startactivity(intent);
    }
   });
   builder.setnegativebutton("取消", new onclicklistener() {

    public void onclick(dialoginterface dialog, int which) {
     finish();
    }
   });
   builder.create().show();
  }
 }检测网络的类isnetworkconnected():

[java]

<span style="white-space: pre"> </span>/**
     * 判断系统的网络是否可用
     * @return
     */
    private boolean isnetworkconnected(){
        connectivitymanager cm =    (connectivitymanager) getsystemservice(connectivity_service);
        networkinfo info =cm.getactivenetworkinfo();
        if(info!=null&&info.isconnected()){
            return true;
        }else {
            return false ;
        }
    

 /**
  * 判断系统的网络是否可用
  * @return
  */
 private boolean isnetworkconnected(){
  connectivitymanager cm = (connectivitymanager) getsystemservice(connectivity_service);
  networkinfo info =cm.getactivenetworkinfo();
  if(info!=null&&info.isconnected()){
   return true;
  }else {
   return false ;
  }

这样就完成了一个欢迎界面，给自已的应用加点色彩。当然还要添加配置在manifest文件中
[html]

<activity
            android:name="com.yan.compusassist.splashactivity"
            android:label="@string/application_name" >
            <intent-filter>
                <action android:name="android.intent.action.main" />
                <category android:name="android.intent.category.launcher" />
            </intent-filter>
        </activity>

<activity
            android:name="com.yan.compusassist.splashactivity"
            android:label="@string/application_name" >
            <intent-filter>
                <action android:name="android.intent.action.main" />
                <category android:name="android.intent.category.launcher" />
            </intent-filter>
        </activity>

这样它就会打开应用，启动第一个activity 界面。