Android自定义ViewPager加上滑动条

最新推荐文章于 2021-05-25 17:43:58 发布

原创最新推荐文章于 2021-05-25 17:43:58 发布 · 1.3k 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#android #布局 #界面 #viewpager

本文介绍如何在Android应用中创建一个自定义的ViewPager，并添加滑动条效果。通过修改activity_main.xml布局文件，实现了界面展示，并提供了‘歌单’界面的代码示例。

今天我们来做一个自定义的ViewPager并且加上滑动条的效果。

首先，我们把activity_main.xml作为程序的主xml，代码如下：

<LinearLayout 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:orientation="vertical"
    tools:context=".DiscoverMusicFragment" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="fill_parent"
        android:layout_height="80dp"
        android:background="#FFFFFF" >

        <TextView
            android:id="@+id/gexingtuijian"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="个性推荐"
            android:textColor="#000000"
            android:textSize="18dp" />

        <TextView
            android:id="@+id/gedan"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="歌单"
            android:textColor="#000000"
            android:textSize="18dp" />

        <TextView
            android:id="@+id/zhubodiantai"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="主播电台"
            android:textColor="#000000"
            android:textSize="18dp" />

        <TextView
            android:id="@+id/paihangbang"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="排行榜"
            android:textColor="#000000"
            android:textSize="18dp" />
    </LinearLayout>

    <ImageView
        android:id="@+id/cursorImage"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:scaleType="matrix"
        android:src="@drawable/a" />

    <android.support.v4.view.ViewPager
        android:id="@+id/vPager"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="#000000"
        android:flipInterval="30"
        android:persistentDrawingCache="animation" />

</LinearLayout>

下面我们开始写“个性推荐”界面，代码如下：

<?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:background="#154154"
    android:orientation="vertical" >
    

</LinearLayout>

为了方便，我们只添加一个颜色，每一个界面的颜色都不同，快速的来实现这个自定义的ViewPager的功能。

“歌单”界面，代码如下：

<?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:background="#878536"
    android:orientation="vertical" >
    

</LinearLayout>

“主播电台”界面，代码如下：

<?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:background="#256397"
    android:orientation="vertical" >
    

</LinearLayout>

“排行榜”界面，代码如下：

<?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:background="#964236"
    android:orientation="vertical" >
    

</LinearLayout>

好了，四个界面的布局都已经写完了，下面开始重要的代码部分，我们需要些一个适配器来管理滑动的效果，以及当点击标签的时候会直接滑动到标签界面。

public class MainFragmentPagerAdapter extends FragmentPagerAdapter {
	private ArrayList<Fragment> fragments;

	public MainFragmentPagerAdapter(FragmentManager fm) {
		super(fm);
	}

	public MainFragmentPagerAdapter(FragmentManager fm,
			ArrayList<Fragment> fragments) {
		super(fm);
		this.fragments = fragments;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see android.support.v4.app.FragmentPagerAdapter#getItem(int)
	 */
	@Override
	public Fragment getItem(int arg0) {
		return fragments.get(arg0);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see android.support.v4.view.PagerAdapter#getCount()
	 */
	@Override
	public int getCount() {
		return fragments.size();
	}

	@Override
	public int getItemPosition(Object object) {
		// TODO Auto-generated method stub
		return super.getItemPosition(object);
	}
}

我们把MainActivity作为程序的主Activity，代码如下所示：

public class MainActivity extends FragmentActivity {
	private ViewPager mPager;// 页卡内容
	private ArrayList<Fragment> listViews; // Tab页面列表
	private ImageView cursor;// 动画图片
	private TextView t1, t2, t3;// 页卡头标
	private int offset = 0;// 动画图片偏移量
	private int currIndex = 0;// 当前页卡编号
	private int bmpW;// 动画图片宽度
	OneFragment oneFragment = new OneFragment();
	TWOFragment twoFragment = new TWOFragment();
	THREEFragment thrFragment = new THREEFragment();

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

	private void InitTextView() {
		t1 = (TextView) findViewById(R.id.text1);
		t2 = (TextView) findViewById(R.id.text2);
		t3 = (TextView) findViewById(R.id.text3);
		t1.setOnClickListener(new MyOnClickListener(0));
		t2.setOnClickListener(new MyOnClickListener(1));
		t3.setOnClickListener(new MyOnClickListener(2));
	}

	/**
	 * 头标点击监听
	 */
	public class MyOnClickListener implements View.OnClickListener {
		private int index = 0;

		public MyOnClickListener(int i) {
			index = i;
		}

		@Override
		public void onClick(View v) {
			mPager.setCurrentItem(index);
		}
	};

	/**
	 * 初始化ViewPager
	 */
	private void InitViewPager() {
		mPager = (ViewPager) findViewById(R.id.vPager);
		listViews = new ArrayList<Fragment>();
		/*
		 * LayoutInflater mInflater = getLayoutInflater();
		 * listViews.add(mInflater.inflate(R.layout.one, null));
		 * listViews.add(mInflater.inflate(R.layout.two, null));
		 * listViews.add(mInflater.inflate(R.layout.three, null));
		 */
		listViews.add(oneFragment);
		listViews.add(twoFragment);
		listViews.add(thrFragment);
		// 用support包，只能用getSupportFragmentManager();
		FragmentManager fragmentManager = this.getSupportFragmentManager();
		// 通过fragment适配器把fragment添加入viewpager中
		mPager.setAdapter(new MainFragmentPagerAdapter(fragmentManager,
				listViews));
		mPager.setCurrentItem(0);
		mPager.setOnPageChangeListener(new MyOnPageChangeListener());
	}

	/**
	 * ViewPager适配器
	 */
	public class MyPagerAdapter extends PagerAdapter {
		public List<View> mListViews;

		public MyPagerAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}

		@Override
		public void destroyItem(View arg0, int arg1, Object arg2) {
			((ViewPager) arg0).removeView(mListViews.get(arg1));
		}

		@Override
		public void finishUpdate(View arg0) {
		}

		@Override
		public int getCount() {
			return mListViews.size();
		}

		@Override
		public Object instantiateItem(View arg0, int arg1) {
			((ViewPager) arg0).addView(mListViews.get(arg1), 0);
			return mListViews.get(arg1);
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {
			return arg0 == (arg1);
		}

		@Override
		public void restoreState(Parcelable arg0, ClassLoader arg1) {
		}

		@Override
		public Parcelable saveState() {
			return null;
		}

		@Override
		public void startUpdate(View arg0) {
		}
	}

	/**
	 * 初始化动画
	 */
	private void InitImageView() {
		cursor = (ImageView) findViewById(R.id.cursor);
		bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.a)
				.getWidth();// 获取图片宽度
		DisplayMetrics dm = new DisplayMetrics();
		getWindowManager().getDefaultDisplay().getMetrics(dm);
		int screenW = dm.widthPixels;// 获取分辨率宽度
		offset = (screenW / 3 - bmpW) / 2;// 计算偏移量
		Matrix matrix = new Matrix();
		matrix.postTranslate(offset, 0);
		cursor.setImageMatrix(matrix);// 设置动画初始位置
	}

	/**
	 * 页卡切换监听,改变动画位置
	 */
	public class MyOnPageChangeListener implements OnPageChangeListener {
		int one, two;

		@Override
		public void onPageSelected(int arg0) {
			one = offset * 2 + bmpW;// 页卡1 -> 页卡2 偏移量
			two = one * 2;// 页卡1 -> 页卡3 偏移量
			Animation animation = null;
			switch (arg0) {
			case 0:
				if (currIndex == 1) {
					animation = new TranslateAnimation(one, 0, 0, 0);
				} else if (currIndex == 2) {
					animation = new TranslateAnimation(two, 0, 0, 0);
				}
				break;
			case 1:
				if (currIndex == 0) {
					animation = new TranslateAnimation(offset, one, 0, 0);
				} else if (currIndex == 2) {
					animation = new TranslateAnimation(two, one, 0, 0);
				}
				break;
			case 2:
				if (currIndex == 0) {
					animation = new TranslateAnimation(offset, two, 0, 0);
				} else if (currIndex == 1) {
					animation = new TranslateAnimation(one, two, 0, 0);
				}
				break;
			}
			currIndex = arg0;
			animation.setFillAfter(true);// True:图片停在动画结束位置
			animation.setDuration(300);
			cursor.startAnimation(animation);
		}

		@Override
		public void onPageScrolled(int arg0, float arg1, int arg2) {
		}

		@Override
		public void onPageScrollStateChanged(int arg0) {
		}
	}
}

代码看不懂的上面有注释。

好了，今天的讲解就到这里，谢谢！