Android 图片自动切换

Android 图片自动切换

效果图：

思路： 利用 android.support.v4.view.ViewPager 和线程实现图片切换。
1. 首先把图片放入分别放入不同的 ImageView
2.然后重写一下 ViewPager 的 适配器 PagerAdapter
3.然后重写一个实现更新界面等操作
4：在onStart里面切换图片

---

配置文件代码如下：

<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" >

    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="200dip"
        >

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

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="35dip"
            android:orientation="vertical"
            android:layout_gravity="bottom"
            android:gravity="center"
            android:background="#33000000"
            >

            <TextView
                android:id="@+id/tv_test_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="图片标题"
                android:textColor="@android:color/white"
                />

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:layout_marginTop="3dip"
                >

                <View
                    android:id="@+id/dot_0"
                    android:layout_width="5dip"
                    android:layout_height="5dip"
                    android:layout_marginLeft="2dip"
                    android:layout_marginRight="2dip"
                    android:background="@drawable/background"
                    />
                <View
                    android:id="@+id/dot_1"
                    android:layout_width="5dip"
                    android:layout_height="5dip"
                    android:layout_marginLeft="2dip"
                    android:layout_marginRight="2dip"
                    android:background="@drawable/background1"
                    />
                <View
                    android:id="@+id/dot_2"
                    android:layout_width="5dip"
                    android:layout_height="5dip"
                    android:layout_marginLeft="2dip"
                    android:layout_marginRight="2dip"
                    android:background="@drawable/background2"
                    />
                <View
                    android:id="@+id/dot_3"
                    android:layout_width="5dip"
                    android:layout_height="5dip"
                    android:layout_marginLeft="2dip"
                    android:layout_marginRight="2dip"
                    android:background="@drawable/background3"
                    />
                <View
                    android:id="@+id/dot_4"
                    android:layout_width="5dip"
                    android:layout_height="5dip"
                    android:layout_marginLeft="2dip"
                    android:layout_marginRight="2dip"
                    android:background="@drawable/background4"
                    />

            LinearLayout>


        LinearLayout>

    FrameLayout>


RelativeLayout>

java 文件为：

package androidstudio.android_test_ck;

import android.os.Handler;
import android.os.Message;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class MainTestActivity extends AppCompatActivity {
    private int imageIds[] = {R.drawable.background, R.drawable.background1, R.drawable.background2, R.drawable.background3, R.drawable.background4};
    private ArrayList images = new ArrayList<>();
    private ViewPager vp;
    private int oldPosition = 0;//记录上一次点的位置
    private int currentItem; //当前页面
    private ScheduledExecutorService scheduledExecutorService;
    //图片标题
    private String titles[] = new String[]{"图片1", "图片2", "图片3", "图片4", "图片5"};
    private ArrayList dots = new ArrayList();;
    private TextView title;

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

        for (int i = 0; i < imageIds.length; i++) {
            ImageView imageView = new ImageView(this);
            imageView.setImageResource(imageIds[i]);

            images.add(imageView);
        }


        //显示的点 加入集合
        dots.add(findViewById(R.id.dot_0));
        dots.add(findViewById(R.id.dot_1));
        dots.add(findViewById(R.id.dot_2));
        dots.add(findViewById(R.id.dot_3));
        dots.add(findViewById(R.id.dot_4));

        //获取图片标题的id
        title = (TextView) findViewById(R.id.tv_test_title);

         //获取ViewPager 的id
        vp = (ViewPager) findViewById(R.id.vp);
        vp.setAdapter(new ViewPagerAdapter());

        vp.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
            //设置页面刷新后的图片标题
                title.setText(titles[position]);
                oldPosition = position;
                currentItem = position;
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    class ViewPagerAdapter extends PagerAdapter{

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

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

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
        //将试图移除试图组
            View v =images.get(position);
            container.removeView(v);
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            //将试图添加进试图组
            View v =images.get(position);
            container.addView(v);
            return v;
        }

    }

    @Override
    protected void onStart() {
        super.onStart();
        scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
        //每隔两秒换一张图片
        scheduledExecutorService.scheduleWithFixedDelay(new ViewPagerTask(),2,2, TimeUnit.SECONDS);

    }
    //实现一个碎片的接口
    class ViewPagerTask implements Runnable{

        @Override
        public void run() {
            currentItem = (currentItem+1)%imageIds.length;
            //更新界面
            handler.obtainMessage().sendToTarget();
        }
    }
    //在handler进行碎片跳转
    Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
        vp.setCurrentItem(currentItem);
        }
    };
}