GridView+无线轮播

本文介绍了一个Android应用程序中如何使用异步任务加载网络数据,并通过GridView和ViewPager进行数据展示的方法。包括了初始化数据、解析JSON、使用ImageLoader加载图片等关键步骤。

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public class MainActivity extends AppCompatActivity {
    ArrayList<Author> arr = new ArrayList<Author>();
    private GridView gridView;
    private Adater adater;
    private ViewPager viewPager;
    ArrayList<View> views = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridView = (GridView) findViewById(R.id.gv);
        //创建方法异步获取数据
        init();
        //设置适配器
        adater = new Adater();
        gridView.setAdapter(adater);
    }
    private void init() {
        new AsyncTask<String, String, String>() {
            @Override
            protected String doInBackground(String... strings) {
                //获取网络数据
                String s = initData();
                Log.e("=====", s.toString());
                return s;
            }
            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);
                //解析json
                Gson gson = new Gson();
                NewsData newsData = gson.fromJson(s, NewsData.class);
                //添加进集合
                List<Essay> essay = newsData.getData().getEssay();
                for (int i = 0; i < essay.size(); i++) {
                    List<Author> author = essay.get(i).getAuthor();
                    for (int j = 0; j < author.size(); j++) {
                        String user_name = author.get(j).getUser_name();
                        String web_url = author.get(j).getWeb_url();
                        arr.add(new Author(user_name, web_url));
                    }
                }
                //刷新适配器
                adater.notifyDataSetChanged();
                //加载viewpager
                initPage();
            }
        }.execute("");
    }
    private void initPage() {
        //获取控件
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        //加载viewpager数据
        initPagerDate();
        //设置适配器
        viewPager.setAdapter(new PagerAdapter() {
            @Override
            public int getCount() {
                //int型最大值
                return Integer.MAX_VALUE;
            }

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

            @Override
            public void destroyItem(ViewGroup container, int position, Object object) {
                //移除页面
                int index = position % views.size();
                container.removeView((View)object);
            }

            @Override
            public Object instantiateItem(ViewGroup container, int position) {
                //添加
                int index = position % views.size();
                container.addView(views.get(index));
                return views.get(index);
            }
        });
        //子线程 一秒后发送空信息
        new Thread() {
            @Override
            public void run() {
                while (true) {
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Message message = new Message();
                    handler.sendEmptyMessage(0);
                }
            }
        }.start();
    }
    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            viewPager.setCurrentItem(viewPager.getCurrentItem()+1);
        }
    };

    private void initPagerDate() {
        if (arr != null) {
            for (int i = 0; i < arr.size(); i++) {
                View inflate = View.inflate(MainActivity.this, R.layout.pager, null);
                ImageView images2 = inflate.findViewById(R.id.imageview);
                ImageLoader.getInstance().displayImage(arr.get(i).getWeb_url(), images2);
                views.add(inflate);
            }
        }
    }

    ////获取网络数据
    private String initData() {
        try {
            //路径
            URL url = new URL("http://v3.wufazhuce.com:8000/api/reading/index/?version=3.5.0&platform=android");
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            int code = urlConnection.getResponseCode();
            if (code == 200) {
                InputStream stream = urlConnection.getInputStream();
                ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                int len = 0;
                byte[] bytes = new byte[1024];
                while ((len = stream.read(bytes)) != -1) {
                    outputStream.write(bytes, 0, len);
                }
                String s = new String(outputStream.toByteArray());
                return s;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    //适配器
    class Adater extends BaseAdapter {
        public Adater() {
            super();
        }

        @Override
        public int getCount() {
            if (arr != null) {
                return arr.size();
            }
            return 0;
        }

        @Override
        public Object getItem(int i) {
            return arr.get(i);
        }

        @Override
        public long getItemId(int i) {
            return i;
        }

        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            AAA aaa;
            if (view == null) {
                aaa = new AAA();
                view = LayoutInflater.from(MainActivity.this).inflate(R.layout.gridview, null, false);
                aaa.tv1 = view.findViewById(R.id.tv1);
                aaa.images = view.findViewById(R.id.images);
                view.setTag(aaa);
            } else {
                aaa = (AAA) view.getTag();
            }
            aaa.tv1.setText(arr.get(i).getUser_name());
            ImageLoader.getInstance().displayImage(arr.get(i).getWeb_url(), aaa.images);
            return view;
        }
    }

    //盒子
    class AAA {
        TextView tv1;
        ImageView images;
    }
}

public class MyApp extends Application {
    public void onCreate() {
        DisplayImageOptions options = new DisplayImageOptions.Builder()
                .showImageOnLoading(R.mipmap.ic_launcher).cacheInMemory(true)
                .cacheOnDisk(true).displayer(new FadeInBitmapDisplayer(1500))
                .build();

        ImageLoaderConfiguration configs = new ImageLoaderConfiguration.Builder(
                this).memoryCacheExtraOptions(480, 800)
                .diskCache(new UnlimitedDiscCache(Environment.getExternalStorageDirectory()))
                .memoryCacheSize(2 * 1024 * 1024)
                .diskCacheFileNameGenerator(new Md5FileNameGenerator())
                .defaultDisplayImageOptions(options).build();

        ImageLoader.getInstance().init(configs);
    }

    ;
}
//主布局文件
    <android.support.v4.view.ViewPager
        android:id="@+id/page"
        android:layout_width="match_parent"
        android:layout_height="200dp"></android.support.v4.view.ViewPager>
    <GridView
        android:id="@+id/grid"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="2"></GridView>
(备注:布局文件以及实体类文件根据自己所需去配置,导包,配置权限)

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