Android开发之进度条、拖动条、TabHost
进度条（ProgressBar）
进度条可以带给用户良好的体验，Android系统已经为我们提供了ProgressBar类来完成进度条的效果，我们可以很方便的运用该类。其中最常见的两种进度条是“环形进度条”和“水平进度条”，在布局文件中定义两种进度条的方式比较相似，区别是，定义“水平进度条时”需要加上一项属性“style="?android:attr/progressBarStyleHorizontal"”。ProgressBar类
中常用的方法如下：
ProgressBar.setMax(int max);设置总长度为100
ProgressBar.setProgress(int progress);设置已经开启长度为0,假设设置为50,进度条将进行到一半停止。
实例：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="进度条演示" />
<ProgressBar
android:id="@+id/probarId1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:max="1000"
android:progress="100" />
<ProgressBar
android:id="@+id/probarId2"
style="@android:style/Widget.ProgressBar.Horizontal"
android:layout_marginTop="50dp"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:max="100000"
android:progress="100"
android:secondaryProgress="300"
/>
</LinearLayout>
////////////////// ProgressBarActivity///////////////////
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 ProgressBarActivity extends Activity {
ProgressBar pro = null;
int i = 0;
int proMax = 0;
Handler handler = new Handler();
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
findViews();
}
private void findViews() {
pro = (ProgressBar) this.findViewById(R.id.probarId2);
proMax = pro.getMax();
new Thread(new Runnable() {
public void run() {
while (i < proMax) {
i=dowork();
handler.post(new Runnable() {
public void run() {
pro.setProgress(i);
}
});
}
}
}
).start();
}
public int dowork(){
Log.d("tag", String.valueOf(i));
return i+=1;
}
/*
* //不能用
*
* @Override public void run() { // TODO Auto-generated method stub while
* (i++ < proMax) { pro.setProgress(i); try { Thread.sleep(50); } catch
* (InterruptedException e) { // TODO Auto-generated catch block
* e.printStackTrace(); } } }
*/
}
拖动条(SeekBar)
进度条只能显示进度，用户不能与程序交互，通过对其操作来改变其值。而拖动条就可以实现此功能。拖动条比较常见，如“千千静听”中的播放进度条就是一个拖动条。Android平台中的SeekBar 是ProgressBar 的间接子类。
SeekBar.getProgress()：获取拖动条当前值
调用setOnSeekBarChangeListener() 方法，处理拖动条值变化事件， 把SeekBar.OnSeekBarChangeListener 实例作为参数传入
实例：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<SeekBar
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:max="1000"
android:id="@+id/seekbarId"
/>
</LinearLayout>
////////////////// SeekBarActivity/////////////////
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 SeekBarActivity extends Activity implements OnSeekBarChangeListener{
SeekBar seekbar = null;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.seekbar);
findViews();
}
private void findViews() {
seekbar = (SeekBar) this.findViewById(R.id.seekbarId);
seekbar.setOnSeekBarChangeListener(this);
}
@Override
public void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {
Log.d("tag","changed:" +String.valueOf(arg0.getProgress()));
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
Log.d("tag","start:" +String.valueOf(seekBar.getProgress()));
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
Log.d("tag","stop:" +String.valueOf(seekBar.getProgress()));
}
}
TabHost
<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<LinearLayout
android:id="@+id/tab1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button
android:id="@+id/buttonId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="切换到tab2" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/p2"
android:scaleType="fitCenter"
android:layout_marginTop="20dp"
/>
</LinearLayout>
</TabHost>
/////////////// TabHostActivity///////////
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.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TabHost;
public class TabHostActivity extends TabActivity {
TabHost tabHost = null;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
tabHost = this.getTabHost();
LayoutInflater inflater = LayoutInflater.from(this);
inflater.inflate(R.layout.tabhost, tabHost.getTabContentView(), true);
// tabHost.addTab(tabHost.newTabSpec("tab2").setIndicator(""));
tabHost.addTab(tabHost.newTabSpec("tab1").setIndicator("切换标签")
.setContent(R.id.tab1));
tabHost.addTab(tabHost.newTabSpec("tab2").setIndicator("标签2")
.setContent(new Intent(this, ProgressBarActivity.class)));
findViews();
}
private void findViews() {
Button btn = (Button) this.findViewById(R.id.buttonId);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// tabHost.setCurrentTab(1);
tabHost.setCurrentTabByTag("tab2");
}
});
}
}