Android 范例-个人理财工具之一启动界面实现_Android

Android 实例-个人理财工具之一启动界面实现

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

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/RelativeLayout01" xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_gravity="center_vertical|center_horizontal" 
android:layout_height="wrap_content" 
android:layout_width="wrap_content"> 
<ImageView android:id="@+id/ImageView01" 
android:src="@drawable/logo3" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content">
</ImageView>
<TextView android:id="@+id/TextView01" 
android:text="@string/welcome"
android:layout_below="@id/ImageView01" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content">
</TextView>
</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.

//给主线程发送消息更新imageview
mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
imageview.setAlpha(alpha);
imageview.invalidate();
}
};
new Thread(new Runnable() {
public void run() {
while (b < 2) {
try {
//延时2秒后,每50毫秒更新一次imageview
if (b == 0) {
Thread.sleep(2000);
b = 1;
} else {
Thread.sleep(50);
}
updateApp();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
public void updateApp() {
alpha -= 5;//每次减少alpha 5
if (alpha <= 0) {
b = 2;
Intent in = new Intent(this, com.cola.ui.Frm_Addbills.class);
startActivity(in);//启动下个界面
}
mHandler.sendMessage(mHandler.obtainMessage());
}

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

附ColaBox.java:

package?com.cola.ui;
import?android.app.Activity;
import?android.content.Intent;
import?android.os.Bundle;
import?android.os.Handler;
import?android.os.Message;
import?android.util.Log;
import?android.view.KeyEvent;
import?android.widget.ImageView;
import?android.widget.TextView;
public?class?ColaBox?extends?Activity?{
????private?Handler?mHandler?=?new?Handler();
????ImageView?imageview;
????TextView?textview;
????int?alpha?=?255;
????int?b?=?0;
????public?void?onCreate(Bundle?savedInstanceState)?{
????????super.onCreate(savedInstanceState);
????????setContentView(R.layout.main);
????????imageview?=?(ImageView)?this.findViewById(R.id.ImageView01);
????????textview?=?(TextView)?this.findViewById(R.id.TextView01);
????????Log.v("ColaBox",?"ColaBox?start?...");
????????imageview.setAlpha(alpha);
????????new?Thread(new?Runnable()?{
????????????public?void?run()?{
????????????????initApp(); //初始化程序
????????????????
????????????????while?(b?<?2)?{
????????????????????try?{
????????????????????????if?(b?==?0)?{
????????????????????????????Thread.sleep(2000);
????????????????????????????b?=?1;
????????????????????????}?else?{
????????????????????????????Thread.sleep(50);
????????????????????????}
????????????????????????updateApp();
????????????????????}?catch?(InterruptedException?e)?{
????????????????????????e.printStackTrace();
????????????????????}
????????????????}
????????????}
????????}).start();
????????mHandler?=?new?Handler()?{
????????????@Override
????????????public?void?handleMessage(Message?msg)?{
????????????????super.handleMessage(msg);
????????????????imageview.setAlpha(alpha);
????????????????imageview.invalidate();
????????????}
????????};
????}
????public?void?updateApp()?{
????????alpha?-=?5;
????????if?(alpha?<=?0)?{
????????????b?=?2;
????????????Intent?in?=?new?Intent(this,?com.cola.ui.Frm_Addbills.class);
????????????startActivity(in);
????????}
????????mHandler.sendMessage(mHandler.obtainMessage());
????}
????
????public?void?initApp(){
????????
????}
}

Android 范例-个人理财工具 之一 启动界面实现

Android 范例-个人理财工具之一启动界面实现