Android详细教程（基础篇）：十一、View组件高级篇：SeekBar 详解

7.5. SeekBar (拖动条)

• 掌握拖动条：SeekBar的主要作用
• 掌握SeekBar组件的事件处理操作
• 可以使用SeekBar组件控制手机屏幕的亮度。

public class SeekBar extends AbsSeekBar java.lang.Object    ↳ android.view.View      ↳ android.widget.ProgressBar        ↳ android.widget.AbsSeekBar          ↳ android.widget.SeekBar

 

 

范例一:简单拖动

配置：

"http://schemas.android.com/apk/res/android"      android:orientation="vertical" android:layout_width="fill_parent"      android:layout_height="fill_parent">                android:id="@+id/seekbar"           android:layout_width="fill_parent"           android:layout_height="wrap_content" />      <TextView           android:id="@+id/text"           android:layout_width="fill_parent"           android:layout_height="wrap_content"/>

 

Activity:

package com.makyan.demo; import android.app.Activity; import android.os.Bundle; import android.text.method.ScrollingMovementMethod; import android.widget.SeekBar; import android.widget.TextView; public class SeekBarActivity extends Activity {      private SeekBar seekbar = null;      private TextView text = null;      @Override      public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);           super.setContentView(R.layout.activity_seek_bar);           seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件           text = (TextView) super.findViewById(R.id.text); // 取得组件           text.setMovementMethod(ScrollingMovementMethod.getInstance()); // 文本组件的内容可以滚动           seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl());      }      private class OnSeekBarChangeListenerImpl implements                SeekBar.OnSeekBarChangeListener {           @Override           public void onStartTrackingTouch(SeekBar seekBar) {                SeekBarActivity.this.text.append("*** 开始拖动，当前值："                          + seekBar.getProgress() + "\n");           }           @Override           public void onProgressChanged(SeekBar seekBar, int progress,                     boolean fromUser) {                SeekBarActivity.this.text.append("*** 正在拖动，当前值："                          + seekBar.getProgress() + "\n");           }           @Override           public void onStopTrackingTouch(SeekBar seekBar) {                SeekBarActivity.this.text.append("*** 停止拖动，当前值："                          + seekBar.getProgress() + "\n");           }      } }

演示效果：

范例二：拖动显示图片

配置：

"http://schemas.android.com/apk/res/android"      android:orientation="vertical" android:layout_width="fill_parent"      android:layout_height="fill_parent">      <ImageView           android:id="@+id/pic"           android:src="@drawable/pic_0"           android:layout_width="fill_parent"           android:layout_height="wrap_content"/>                android:id="@+id/seekbar"           android:layout_width="fill_parent"           android:layout_height="wrap_content" />

Activity:

package com.makyan.demo; import android.app.Activity; import android.os.Bundle; import android.widget.ImageView; import android.widget.SeekBar; public class SeekBarActivity extends Activity {      private SeekBar seekbar = null;      private ImageView pic = null;      private int picData[] = new int[] { R.drawable.pic_0, R.drawable.pic_1,                R.drawable.pic_2, R.drawable.pic_3, R.drawable.pic_4,                R.drawable.pic_5, R.drawable.pic_6, R.drawable.pic_7,                R.drawable.pic_8, R.drawable.pic_9 };      @Override      public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);           super.setContentView(R.layout.activity_seek_bar);           seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件           pic = (ImageView) super.findViewById(R.id.pic); // 取得组件           seekbar.setMax(9); // 0 ~ 9的范围           seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl());      }      private class OnSeekBarChangeListenerImpl implements                SeekBar.OnSeekBarChangeListener {           @Override           public void onStartTrackingTouch(SeekBar seekBar) {           }           @Override           public void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {                pic.setImageResource(SeekBarActivity.this.picData[seekBar.getProgress()]);// 设置显示图片           }           @Override           public void onStopTrackingTouch(SeekBar seekBar) {           }      } }

演示效果：

范例三：改变屏幕亮度

WindowManager.LayoutParams layoutParams = super.getWindow().getAttributes() ;

         // 取得屏幕的属性

配置：

android:orientation="vertical" android:layout_width="fill_parent"             android:layout_height="fill_parent">                                    android:id="@+id/pic"                        android:src="@drawable/android_book"                        android:layout_width="fill_parent"                        android:layout_height="wrap_content"/>                                    android:id="@+id/seekbar"                        android:layout_width="fill_parent"                        android:layout_height="wrap_content" />

Activity:

package com.makyan.demo;   import android.app.Activity; import android.os.Bundle; import android.view.WindowManager; import android.widget.SeekBar;   public class SeekBarActivity extends Activity {        private SeekBar seekbar = null;        @Override      public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);           super.setContentView(R.layout.activity_seek_bar);           seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件           seekbar.setMax(100);           seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl());      }        private class OnSeekBarChangeListenerImpl implements SeekBar.OnSeekBarChangeListener {           @Override           public void onStartTrackingTouch(SeekBar seekBar) {           }             @Override           public void onProgressChanged(SeekBar seekBar, int progress,                     boolean fromUser) {                setScreenBrightness((float) seekBar.getProgress() / 100);           }             @Override           public void onStopTrackingTouch(SeekBar seekBar) {           }      }      private void setScreenBrightness(float num) { // 0 ~ 1表示亮度           WindowManager.LayoutParams layoutParams = super.getWindow().getAttributes() ;    // 取得屏幕的属性           layoutParams.screenBrightness = num ;   // 设置屏幕亮度           super.getWindow().setAttributes(layoutParams) ;    // 重新设置窗口的属性      }   }

演示效果就不贴了，很简单。