7.Android之评分条RatingBar和拖动条SeekBar学习

评分条RatingBar和拖动条SeekBar很常见，今天来学习下。

(1)RatingBar评分条

如图:

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:paddingBottom="@dimen/activity_vertical_margin"
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
     tools:context="com.example.ratingbar.MainActivity" >

     <RatingBar
         android:id="@+id/ratingBar1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_alignParentLeft="true"
         android:layout_alignParentTop="true"
         android:layout_marginLeft="22dp"
         android:layout_marginTop="25dp" />

 </RelativeLayout>

RatingBar监听事件：public void setOnRatingBarChangeListener (RatingBar.OnRatingBarChangeListener listener)

(2)拖动他SeekBar使用

首先从工具中拖入一个SeekBar和两个TextView，如图：

代码如下：

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:paddingBottom="@dimen/activity_vertical_margin"
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
     tools:context="com.example.ratingbar.MainActivity" >

     <SeekBar
         android:id="@+id/seekBar1"
         android:max="100"
         android:progress="50"
         android:secondaryProgress="75"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_alignParentLeft="true"
         android:layout_alignParentTop="true"
         android:layout_marginTop="35dp" />

     <TextView
         android:id="@+id/info1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_alignLeft="@+id/seekBar1"
         android:layout_below="@+id/seekBar1"
         android:layout_marginTop="24dp"/>

     <TextView
         android:id="@+id/info2"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_alignLeft="@+id/info1"
         android:layout_below="@+id/info1"
         android:layout_marginTop="32dp"/>

 </RelativeLayout>

然后我们实现OnSeekBarChangeListener接口：public class MainActivity extends Activity implements OnSeekBarChangeListener{...} ,此接口共需要监听三个事件，分别是：
                 数值改变（onProgressChanged）
                 开始拖动（onStartTrackingTouch）
                 停止拖动（onStopTrackingTouch）

完整代码如下：

 package com.example.ratingbar;

 import android.app.Activity;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.widget.SeekBar;
 import android.widget.SeekBar.OnSeekBarChangeListener;
 import android.widget.TextView;

 //实现OnSeekBarChangeListener接口
 public class MainActivity extends Activity implements OnSeekBarChangeListener {

     private SeekBar sbVolumer=null;
     private TextView info1=null;
     private TextView info2=null;  

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         sbVolumer = (SeekBar) findViewById(R.id.seekBar1);
         sbVolumer.setOnSeekBarChangeListener(this);
         info1 = (TextView) findViewById(R.id.info1);
         info2 = (TextView) findViewById(R.id.info2);
     }

     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         // Inflate the menu; this adds items to the action bar if it is present.
         getMenuInflater().inflate(R.menu.main, menu);
         return true;
     }

     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         // Handle action bar item clicks here. The action bar will
         // automatically handle clicks on the Home/Up button, so long
         // as you specify a parent activity in AndroidManifest.xml.
         int id = item.getItemId();
         if (id == R.id.action_settings) {
             return true;
         }
         return super.onOptionsItemSelected(item);
     }

     @Override
     public void onProgressChanged(SeekBar seekBar, int progress,
             boolean fromUser) {

         info1.setText("当前值： " + progress);
     }

     @Override
     public void onStartTrackingTouch(SeekBar seekBar) {

         info2.setText("正在改变当前值");
     }

     @Override
     public void onStopTrackingTouch(SeekBar seekBar) {
         info2.setText("停止拖动");
     }
 }

运行效果：