Android 实例-个人理财工具之一启动界面实现

客官°小女子只卖身不卖艺 2022-08-05 14:28 150阅读 0赞

转　：　 [http://hi.baidu.com/android%5Ffans/blog/item/299c0dfa37a60c116c22eb33.html][http_hi.baidu.com_android_5Ffans_blog_item_299c0dfa37a60c116c22eb33.html]

启动界面的主要功能就是显示一幅启动图像,后台进行系统初始化.

如果是第一次使用本程序,需要初始化本程序的sqlite数据库,建库,建Table,初始化账目数据.

如果不是第一次使用,就进入登记收支记录界面.

界面效果如图:

界面很简单,一个imageview 和一个textview

可是如何是2个view 垂直居中显示,我开始使用linearlayout就没法完成垂直和横向居中.

后来使用RelativeLayout 才搞定了横向居中.

界面的具体xml如下:

main.xml

1.  <?xml version="1.0" encoding="utf-8"?>
2.  <RelativeLayout android:id="@+id/RelativeLayout01" xmlns:android="http://schemas.android.com/apk/res/android"
3.  android:layout\_gravity="center\_vertical|center\_horizontal"
4.  android:layout\_height="wrap\_content"
5.  android:layout\_width="wrap\_content">
6.  <ImageView android:id="@+id/ImageView01"
7.  android:src="@drawable/logo3"
8.  android:layout\_width="wrap\_content"
9.  android:layout\_height="wrap\_content">
10. </ImageView>
11. <TextView android:id="@+id/TextView01"
12. android:text="@string/welcome"
13. android:layout\_below="@id/ImageView01"
14. android:layout\_width="wrap\_content"
15. android:layout\_height="wrap\_content">
16. </TextView>
17. </RelativeLayout>

在这儿我来使用一个小技巧,就是在程序初始化完成后,让图片淡出,然后显示下一个界面.

开始我准备使用一个timer来更新图片的alpha值,后来程序抛出异常 Only the original thread that created a view hierarchy can touch its views.

这才发现android 的ui 控件是线程安全的.

这里需要我们在主线程外,再开一个线程更新界面上的图片.可以使用imageview.invalidate

关于如何另开一个线程更新界面的相关代码如下.

1.  //给主线程发送消息更新imageview
2.  mHandler = new Handler() \{
3.  @Override
4.  public void handleMessage(Message msg) \{
5.  super.handleMessage(msg);
6.  imageview.setAlpha(alpha);
7.  imageview.invalidate();
8.  \}
9.  \};
10. new Thread(new Runnable() \{
11. public void run() \{
12. while (b < 2) \{
13. try \{
14. //延时2秒后,每50毫秒更新一次imageview
15. if (b == 0) \{
16. Thread.sleep(2000);
17. b = 1;
18. \} else \{
19. Thread.sleep(50);
20. \}
21. updateApp();
22. \} catch (InterruptedException e) \{
23. e.printStackTrace();
24. \}
25. \}
26. \}
27. \}).start();
28. public void updateApp() \{
29. alpha -= 5;//每次减少alpha 5
30. if (alpha <= 0) \{
31. b = 2;
32. Intent in = new Intent(this, com.cola.ui.Frm\_Addbills.class);
33. startActivity(in);//启动下个界面
34. \}
35. mHandler.sendMessage(mHandler.obtainMessage());
36. \}

通过这段代码,我们能够理解android 里面如何对ui视图进行更新.

下篇文章我们来看看sqlite的使用.如何初始化程序.

关于handler,invalidate 的用法,

大家还可以参考这篇文章.[http://www.blogjava.net/gooogle/archive/2008/03/05/184030.html][http_www.blogjava.net_gooogle_archive_2008_03_05_184030.html]

附ColaBox.java:

1.  package com.cola.ui;
2.  import android.app.Activity;
3.  import android.content.Intent;
4.  import android.os.Bundle;
5.  import android.os.Handler;
6.  import android.os.Message;
7.  import android.util.Log;
8.  import android.view.KeyEvent;
9.  import android.widget.ImageView;
10. import android.widget.TextView;
11. public class ColaBox extends Activity \{
12.     private Handler mHandler = new Handler();
13.      ImageView imageview;
14.      TextView textview;
15.     int alpha = 255;
16.     int b = 0;
17.     public void onCreate(Bundle savedInstanceState) \{
18.         super.onCreate(savedInstanceState);
19.          setContentView(R.layout.main);
20.          imageview = (ImageView) this.findViewById(R.id.ImageView01);
21.          textview = (TextView) this.findViewById(R.id.TextView01);
22.          Log.v("ColaBox", "ColaBox start ...");
23.          imageview.setAlpha(alpha);
24.         new Thread(new Runnable() \{
25.             public void run() \{
26.                  initApp(); //初始化程序
27.                 
28.                 while (b < 2) \{
29.                     try \{
30.                         if (b == 0) \{
31.                              Thread.sleep(2000);
32.                              b = 1;
33.                          \} else \{
34.                              Thread.sleep(50);
35.                          \}
36.                          updateApp();
37.                      \} catch (InterruptedException e) \{
38.                          e.printStackTrace();
39.                      \}
40.                  \}
41.              \}
42.          \}).start();
43.          mHandler = new Handler() \{
44.             @Override
45.             public void handleMessage(Message msg) \{
46.                 super.handleMessage(msg);
47.                  imageview.setAlpha(alpha);
48.                  imageview.invalidate();
49.              \}
50.          \};
51.      \}
52.     public void updateApp() \{
53.          alpha -= 5;
54.         if (alpha <= 0) \{
55.              b = 2;
56.              Intent in = new Intent(this, com.cola.ui.Frm\_Addbills.class);
57.              startActivity(in);
58.          \}
59.          mHandler.sendMessage(mHandler.obtainMessage());
60.      \}
61.     
62.     public void initApp()\{
63.         
64.      \}
65. \}

[http_hi.baidu.com_android_5Ffans_blog_item_299c0dfa37a60c116c22eb33.html]: http://hi.baidu.com/android%5Ffans/blog/item/299c0dfa37a60c116c22eb33.html
[http_www.blogjava.net_gooogle_archive_2008_03_05_184030.html]: http://www.blogjava.net/gooogle/archive/2008/03/05/184030.html