今天呢,学习UI组件中的:ProgressBar、SeekBar、TabHost、ImageView
那么,就通过实例来了解上述四个组件。
首先介绍ProgressBar(即进度条)
先创建progressbar_layout.xml布局文件:
这里定义了两个进度条,其中在未定义其样式的情况下,它是一个圆圈形式的进度条。
然后在ProgressBar.java文件中调用其布局,实现其代码:
package cn.class3g.activity;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.widget.ProgressBar;
public class ProgressBarDemo extends Activity{
ProgressBar progressbar = null;
static int i = 0;
int progressbarMax = 0;
Handler handler = new Handler();
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.progressbar_layout);
findViews();
}
private void findViews() {
progressbar = (ProgressBar) this.findViewById(R.id.progressbar2);
progressbar.setMax(1000);
progressbarMax = progressbar.getMax();
new Thread(new Runnable(){
public void run(){
while(i< progressbarMax){
i=doWork();
handler.post(new Runnable(){
public void run(){
progressbar.setProgress(i);
}
});
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}).start();
}
public int doWork(){
Log.d("TAG", String.valueOf(i));
return ++i;
}
}
启动虚拟机:
Ok,接下来了解SeekBar(拖动条)。
同样的建立seekbar.xml布局文件:
然后,在SeekBar.java文件中调用其布局,实现日志输出:
package cn.class3g.activity;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
public class SeekBarDemo extends Activity implements OnSeekBarChangeListener {
SeekBar seekbar = null;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.seekbar_layout);
findViews();
}
private void findViews() {
seekbar = (SeekBar) this.findViewById(R.id.seekbar);
seekbar.setOnSeekBarChangeListener(this);
}
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
Log.d("TAG", "changed: "+ String.valueOf(seekBar.getProgress()));
}
public void onStartTrackingTouch(SeekBar seekBar) {
Log.d("TAG", "start: "+ String.valueOf(seekBar.getProgress()));
}
public void onStopTrackingTouch(SeekBar seekBar) {
Log.d("TAG", "stop: "+ String.valueOf(seekBar.getProgress()));
}
}
启动虚拟机
:
接下来,来了解ImageView组件
先创建imageview_layout.xml组件:
然后在ImageViewDemo.java文件中调用其布局文件:
package cn.class3g.activity;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
public class ImageViewDemo extends Activity implements OnTouchListener {
ImageView imageView1, imageView2;
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
this.setContentView(R.layout.imageview_layout);
findViews();
}
private void findViews() {
imageView1 = (ImageView) findViewById(R.id.img1);
imageView2 = (ImageView) findViewById(R.id.img2);
imageView1.setOnTouchListener(this);
}
public boolean onTouch(View v, MotionEvent event) {
float scale = 412 / 320;
int x = (int) (event.getX() * scale);
int y = (int) (event.getY() * scale);
//尝试考虑解决边界问题
int width = (int) (100 * scale);
int height = (int) (100 * scale);
BitmapDrawable bitmapDrawable = (BitmapDrawable) imageView1.getDrawable();
imageView2.setImageBitmap(Bitmap.createBitmap(bitmapDrawable.getBitmap(),
x,y, width, height));
return false;
}
}
这个实例中,实现了一个类似于图片截图的功能(固定尺寸)
启动虚拟机:
这里需要注意了,因为在ImageViewDemo.java中下边的小图是取的固定尺寸,当点击图片的坐标超出其尺寸时,将出现错误。
最后,来了解TabHost(界面切换)组件
首先,同样的创建tabhost_layout.xml布局文件:
然后TabHostDemo.java文件中实现下边的代码,这里其切换的页面为上述几个组件实现的界面:
package cn.class3g.activity;
import android.app.TabActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.TabHost;
public class TabHostDemo extends TabActivity {
TabHost tabHost = null;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
tabHost = this.getTabHost();
LayoutInflater inflater = LayoutInflater.from(this);
inflater.inflate(R.layout.tabhost_layout, tabHost.getTabContentView(),
true);
tabHost.addTab(tabHost.newTabSpec("tab1").setIndicator("切换标签")
.setContent(R.id.tab1));
tabHost.addTab(tabHost.newTabSpec("tab2").setIndicator("SeekBar demo")
.setContent(new Intent(this, SeekBarDemo.class)));
tabHost.addTab(tabHost.newTabSpec("tab3")
.setIndicator("ImageView Demo")
.setContent(new Intent(this, ImageViewDemo.class)));
findViews();
}
private void findViews() {
Button btn = (Button) this.findViewById(R.id.button);
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// tabHost.setCurrentTab(1);//根据其位置切换
tabHost.setCurrentTabByTag("tab2");//根据其名称切换
}
});
}
}
启动虚拟机:
Ok,成功界面切换.