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：