轮播图

来源：互联网发布：前瞻数据库编辑：程序博客网时间：2024/05/19 16:28

1 handler 和全局变量

private ViewPager viewPager;
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
if (msg.what == 0){
//viewPager显示下一页
viewPager.setCurrentItem(viewPager.getCurrentItem() +1);

//再次发送延时消息
handler.sendEmptyMessageDelayed(0,2000);
}
}
};
private LinearLayout linearLayout;
private List<ImageView> images;

2 oncreate的代码

viewPager = (ViewPager) findViewById(R.id.view_pager);
linearLayout = (LinearLayout) findViewById(R.id.linear_layout);

//获取轮播图的数据
getDataFromNet();

3 getDataFromNet();自己的方法还有配置的小圆点

private void getDataFromNet() {
AsyncTask<Void, Void, String> asyncTask = new AsyncTask<Void, Void, String>() {
@Override
protected String doInBackground(Void... voids) {

String path = "http://www.yulin520.com/a2a/impressApi/news/mergeList?pageSize=5&page=1";

try {
URL url = new URL(path);

HttpURLConnection connection = (HttpURLConnection) url.openConnection();

connection.setRequestMethod("GET");
connection.setReadTimeout(5000);
connection.setConnectTimeout(5000);

int responseCode = connection.getResponseCode();
if (responseCode == 200){
InputStream inputStream = connection.getInputStream();

String json = streamToString(inputStream,"utf-8");

return json;

}

} catch (Exception e) {
e.printStackTrace();
}

return null;
}

@Override
protected void onPostExecute(String s) {
//打印以下数据看看是否获取到
Log.i("----",s);

if (s != null){
Gson gson = new Gson();

DataDataBean dataDataBean = gson.fromJson(s, DataDataBean.class);

List<DataDataBean.DataBean> list = dataDataBean.getData();

//给viewPager设置适配器
MyAdapter myAdapter = new MyAdapter(MainActivity.this, list,handler);

//设置适配器
viewPager.setAdapter(myAdapter);

//3.根据集合的长度动态添加小圆点...linearLayout
initDoc(list);

//2.手动的可以无限滑动
viewPager.setCurrentItem(list.size()*100000);//设置当前展示中间某个足够大的位置

handler.sendEmptyMessageDelayed(0,2000);//发送一个延时的空消息

//viewPage设置监听事件
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

}

/**
* 当选中某个页面的时候,把当前的小圆点背景变成绿色
* @param position
*/
@Override
public void onPageSelected(int position) {

for (int i=0;i<images.size();i++){
if (i == position%images.size()){

images.get(i).setImageResource(R.drawable.shape_01);
}else {
images.get(i).setImageResource(R.drawable.shape_02);
}

}

}

@Override
public void onPageScrollStateChanged(int state) {

}
});
}

}
};

asyncTask.execute();

}

/**
* 动态添加小圆点
* @param list
*/
private void initDoc(List<DataDataBean.DataBean> list) {
//1.需要一个集合记录一下小圆点的imageView控件
images = new ArrayList<ImageView>();
//2...linearLayout上面的视图清空一下再去添加
linearLayout.removeAllViews();

for (int i=0;i<list.size();i++){
ImageView imageView = new ImageView(MainActivity.this);

if (i==0){
imageView.setImageResource(R.drawable.shape_01);
}else {
imageView.setImageResource(R.drawable.shape_02);
}

//添加到集合去
images.add(imageView);
//添加到线性布局上

//这是布局参数,,刚开始小圆点之间没有距离,所以使用java代码指定宽度高度,并且指定小圆点之间的距离
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT);

params.setMargins(5,0,5,0);

linearLayout.addView(imageView,params);
}

}

private String streamToString(InputStream inputStream,String charset) {
try {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream,charset);

BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String s = null;
StringBuilder builder = new StringBuilder();
while ((s = bufferedReader.readLine()) != null){
builder.append(s);
}

bufferedReader.close();
return builder.toString();

} catch (Exception e) {
e.printStackTrace();
}

return null;
}

4 Myadapter配置

Context context;
List<DataDataBean.DataBean> list;
Handler handler;

public MyAdapter(Context context, List<DataDataBean.DataBean> list, Handler handler) {
this.context = context;
this.list = list;
this.handler = handler;
}

@Override
public int getCount() {
return Integer.MAX_VALUE;
}

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

/**
* viewPager具有预加载,默认的前后加载一页,,,默认的容器里面最多三页
* @param container
* @param position
* @return
*/
@Override
public Object instantiateItem(ViewGroup container, int position) {

//1.把这个当前展示的视图添加到容器中...container
ImageView imageView = new ImageView(context);

//..........使图片平铺整个imageView控件
imageView.setScaleType(ImageView.ScaleType.FIT_XY);

//imageLoader加载图片到这个imageView控件上
ImageLoader.getInstance().displayImage(list.get(position %list.size()).getImg(),imageView,ImageLoaderUtil.getDefaultOption());

//给imageView设置触摸的监听事件
imageView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {

int action = motionEvent.getAction();//获取手指的动作
switch (action){
case MotionEvent.ACTION_DOWN://按下的动作...应该取消发送消息的操作
handler.removeCallbacksAndMessages(null);

break;
case MotionEvent.ACTION_MOVE://移动的动作
handler.removeCallbacksAndMessages(null);

break;
case MotionEvent.ACTION_CANCEL://取消
//重新发送
handler.sendEmptyMessageDelayed(0,2000);

break;
case MotionEvent.ACTION_UP://抬起的动作
handler.sendEmptyMessageDelayed(0,2000);

break;
}

//返回true表示自己处理触摸事件
return true;
}
});

container.addView(imageView);//添加到容器
//2.把当前展示的视图返回

return imageView;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {

//销毁视图
container.removeView((View) object);
}

5 布局配置

<android.support.v4.view.ViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="200dp">

</android.support.v4.view.ViewPager>

<LinearLayout
android:orientation="horizontal"
android:id="@+id/linear_layout"
android:layout_alignBottom="@+id/view_pager"
android:layout_centerHorizontal="true"
android:layout_marginBottom="20dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content">

</LinearLayout>

6 drawable里的小圆点配置创建 shape

1.<solid android:color="#00ff00"/>

<corners android:radius="10dp"/>

<size android:height="10dp" android:width="10dp"/>

2 <solid android:color="#ff0000"/>

<corners android:radius="10dp"/>

<size android:height="10dp" android:width="10dp"/>

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