android image滑块

Android图像滑块将整个屏幕滑动到另一屏幕。图像滑块由支持库提供的ViewPager创建。要实现图像滑块，你需要继承扩展PagerAdapter的ViewPager类。

图像滑块示例

让我们来看一个Android图片滑块的示例。

activity_main.xml

在activity_main.xml文件中，我们将ViewPager包装在RelativeLayout中。

文件：activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_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.test.imageslider.MainActivity">


    <android.support.v4.view.ViewPager
        android:id="@+id/viewPage"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />

</RelativeLayout>

活动类

文件：MainActivity.java

package com.example.test.imageslider;

import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

        ViewPager mViewPager = (ViewPager) findViewById(R.id.viewPage);
        ImageAdapter adapterView = new ImageAdapter(this);
        mViewPager.setAdapter(adapterView);
    }
}

ImageAdapter类

现在创建ImageAdapter类，该类扩展了用于Android图像滑块的PagerAdapter。

将一些图像放在要滑动的可绘制文件夹中。

文件：ImageAdapter.java

package com.example.test.imageslider;

import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

public class ImageAdapter extends PagerAdapter{
    Context mContext;

    ImageAdapter(Context context) {
        this.mContext = context;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((ImageView) object);
    }

    private int[] sliderImageId = new int[]{
            R.drawable.image1, R.drawable.image2, R.drawable.image3, R.drawable.image4, R.drawable.image5, };

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        ImageView imageView = new ImageView(mContext);
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setImageResource(sliderImageId[position]);
        ((ViewPager) container).addView(imageView, 0);
        return imageView;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        ((ViewPager) container).removeView((ImageView) object);
    }

    @Override
    public int getCount() {
        return sliderImageId.length;
    }
}

我们需要重写PagerAdapter类的以下方法。