ViewPager輪播圖 Handler方式實現
阿新 • • 發佈：2018-11-22
1.提取的基類BaseActivity
package com.example.viewpager_demo; import android.os.Bundle; import android.support.annotation.Nullable; import android.support.v7.app.AppCompatActivity; public abstract class BaseActivity extends AppCompatActivity { @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(getLayoutResId()); //初始化檢視 initView(); //載入資料 initData(); } protected abstract int getLayoutResId(); //初始化檢視 protected abstract void initView(); //載入資料 protected abstract void initData(); }
2.MainActivity主頁面
package com.example.viewpager_demo; import android.annotation.SuppressLint; import android.os.Handler; import android.os.Message; import android.support.v4.view.ViewPager; import android.util.TypedValue; import android.view.ViewGroup; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.TextView; import android.widget.Toast; import com.example.Adaper.BunnerAdaper; import com.example.Bean.BunnerBean; import com.example.Util.NetUtils; public class MainActivity extends BaseActivity { private String imageUrl = "https://api.tianapi.com/wxnew/?key=605fa0a929c8d8b116424df0510c6b2a&num=6&page=1"; private ViewPager viewPager; private LinearLayout linearLayout; private TextView textView; private BunnerAdaper adaper; @Override protected int getLayoutResId() { return R.layout.activity_main; } //初始化view @Override protected void initView() { viewPager = findViewById(R.id.v_pager); linearLayout = findViewById(R.id.L_layout); textView = findViewById(R.id.text); //建立介面卡 adaper = new BunnerAdaper(this); //設定給介面卡 viewPager.setAdapter(adaper); //滑動監聽 viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() { //快取的點 private int index = -1; @Override public void onPageScrolled(int i, float v, int i1) { } @Override public void onPageSelected(int i) { //改變textview textView.setText(adaper.getItem(i).getTitle()); //改變當前點 linearLayout.getChildAt(i % linearLayout.getChildCount()).setSelected(true); //還原原來的點 if (index >= 0) { linearLayout.getChildAt(index % linearLayout.getChildCount()).setSelected(false); } index = i; } @Override public void onPageScrollStateChanged(int i) { } }); } //載入資料 @Override protected void initData() { NetUtils.getInstance().getRequest(imageUrl, BunnerBean.class, new NetUtils.CallBack<BunnerBean>() { @Override public void onSuccess(BunnerBean o) { if (o == null || !o.isSuccess()) { Toast.makeText(MainActivity.this, "請求錯誤", Toast.LENGTH_SHORT).show(); return; } adaper.setmList(o.getNewslist()); //初始化小圓點的方法 initDot(o.getNewslist().size()); //切換到中間位置 int center = adaper.getCount() / 2; center = center - center % o.getNewslist().size(); viewPager.setCurrentItem(center); //開啟輪播 startLooper(); } }); } //建立handler @SuppressLint("HandlerLeak") private Handler handler = new Handler() { @Override public void handleMessage(Message msg) { viewPager.setCurrentItem(viewPager.getCurrentItem() + 1); handler.sendEmptyMessageDelayed(0, 2000); } }; //開啟輪播 private void startLooper() { handler.removeCallbacksAndMessages(null); handler.sendEmptyMessageDelayed(0, 2000); } //初始化小圓點 private void initDot(int size) { linearLayout.removeAllViews(); for (int i = 0; i < size; i++) { ImageView imageView = new ImageView(this); imageView.setBackgroundResource(R.drawable.select_dot); //佈局引數 寬高包裹 LinearLayout.LayoutParams params = new LinearLayout.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT ); int marage = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 5, getResources().getDisplayMetrics()); params.leftMargin = marage; params.rightMargin = marage; linearLayout.addView(imageView, params); } } }
3.介面卡頁面
package com.example.Adaper; import android.content.Context; import android.support.annotation.NonNull; import android.support.v4.view.PagerAdapter; import android.view.View; import android.view.ViewGroup; import android.widget.ImageView; import com.example.Bean.BunnerBean; import com.nostra13.universalimageloader.core.ImageLoader; import java.util.ArrayList; import java.util.List; public class BunnerAdaper extends PagerAdapter { private List<BunnerBean.NewslistBean> mList; private Context mContext; public BunnerAdaper(Context mContext) { this.mContext = mContext; //出始化 mList = new ArrayList<>(); } public void setmList(List<BunnerBean.NewslistBean> lists){ mList.clear(); if(lists!=null){ mList.addAll(lists); } notifyDataSetChanged(); } @Override public int getCount() { return mList.size()>0?5000:0; } @Override public boolean isViewFromObject(@NonNull View view, @NonNull Object o) { return view == o; } public BunnerBean.NewslistBean getItem(int position){ return mList.get(position%mList.size()); } @NonNull @Override public Object instantiateItem(@NonNull ViewGroup container, int position) { ImageView imageView = new ImageView(mContext); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); container.addView(imageView); ImageLoader.getInstance().displayImage(getItem(position).getPicUrl(),imageView); return imageView; } @Override public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) { container.removeView((View) object); } }
4.工具類
package com.example.Util;
import android.annotation.SuppressLint;
import android.os.AsyncTask;
import com.google.gson.Gson;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class NetUtils {
private static NetUtils instance;
private Gson gson;
public NetUtils() {
gson = new Gson();
}
public static NetUtils getInstance() {
if(instance == null){
instance = new NetUtils();
}
return instance;
}
//執行一個網路請求返回string
public String getRequest(String urlStr){
String result = "";
try {
//定義url地址
URL url = new URL(urlStr);
//開啟連線
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//設定請求格式
urlConnection.setRequestMethod("GET");
//設定超時
urlConnection.setReadTimeout(5000);
urlConnection.setConnectTimeout(5000);
//獲取請求碼
int responseCode = urlConnection.getResponseCode();
if(responseCode == 200){
result = stream2String(urlConnection.getInputStream());
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
//將位元組流轉換為字元流
private String stream2String(InputStream inputStream) throws IOException {
StringBuilder builder = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
for (String tmp = br.readLine();tmp!=null;tmp = br.readLine()){
builder.append(tmp);
}
return builder.toString();
}
//執行一個網路請求返回bean
public <E> E getRequest(String urlStr,Class clazz){
return (E) gson.fromJson(getRequest(urlStr),clazz);
}
//定義介面
public interface CallBack<E>{
void onSuccess(E e);
}
//非同步 回撥請求
@SuppressLint("StaticFieldLeak")
public void getRequest(String urlStr, final Class clazz, final CallBack callBack){
new AsyncTask<String,Void,Object>(){
@Override
protected Object doInBackground(String... strings) {
return getRequest(strings[0],clazz);
}
@Override
protected void onPostExecute(Object o) {
callBack.onSuccess(o);
}
}.execute(urlStr);
}
}
5.Bean類
package com.example.Bean;
import java.util.List;
public class BunnerBean {
private int code;
private String msg;
private List<NewslistBean> newslist;
private final int SUCCESS_CODE = 200;
public boolean isSuccess(){
return SUCCESS_CODE == code;
}
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public List<NewslistBean> getNewslist() {
return newslist;
}
public void setNewslist(List<NewslistBean> newslist) {
this.newslist = newslist;
}
public static class NewslistBean {
private String ctime;
private String title;
private String description;
private String picUrl;
private String url;
public String getCtime() {
return ctime;
}
public void setCtime(String ctime) {
this.ctime = ctime;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getPicUrl() {
return picUrl;
}
public void setPicUrl(String picUrl) {
this.picUrl = picUrl;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
}
}
6.Application初始化圖片頁面
package com.example.Application;
import android.app.Application;
import android.graphics.Bitmap;
import com.example.viewpager_demo.R;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
public class App extends Application {
@Override
public void onCreate() {
ImageLoader.getInstance().init(new ImageLoaderConfiguration.Builder(this)
.diskCacheSize(50*1024*1024)
.memoryCacheSizePercentage(10)
.defaultDisplayImageOptions(new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(true)
.bitmapConfig(Bitmap.Config.RGB_565)
.showImageOnLoading(R.mipmap.ic_launcher)
.showImageForEmptyUri(R.mipmap.ic_launcher)
.showImageOnFail(R.mipmap.ic_launcher)
.build())
.build());
super.onCreate();
}
}
7.佈局頁面
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.v4.view.ViewPager
android:id="@+id/v_pager"
android:layout_width="0dp"
android:layout_height="200dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
/>
<LinearLayout
android:id="@+id/L_layout"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:orientation="horizontal"
app:layout_constraintRight_toRightOf="@id/v_pager"
app:layout_constraintBottom_toBottomOf="@id/v_pager"
android:padding="8dp"
/>
<TextView
android:id="@+id/text"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:maxLines="1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@id/L_layout"
app:layout_constraintBottom_toBottomOf="@id/v_pager"
android:ellipsize="end"
/>
</android.support.constraint.ConstraintLayout>
7.輪播圖小圓點
7.1預設圓點顏色
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval"
>
<size
android:width="8dp"
android:height="8dp"
/>
<solid
android:color="#909090"
/>
</shape>
7.2選中圓點顏色
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval"
>
<size
android:width="8dp"
android:height="8dp"
/>
<solid
android:color="#900000"
/>
</shape>
7.3select設定選中
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_sel_dot" android:state_selected="true"></item>
<item android:drawable="@drawable/shape_normal_dot" ></item>
</selector>