GridView分頁與緩存結合

在Android開發中，GridView分頁與緩存的結合可以提高應用程序的性能和用戶體驗。以下是實現GridView分頁與緩存結合的步驟：

1. 創建一個數據模型類（ItemModel）：

public class ItemModel {
    private String title;
    // 其他屬性

    public ItemModel(String title) {
        this.title = title;
    }

    public String getTitle() {
        return title;
    }

    // 其他getter和setter方法
}

2. 創建一個適配器類（MyAdapter）：

public class MyAdapter extends BaseAdapter {
    private Context context;
    private List<ItemModel> itemList;
    private LayoutInflater inflater;

    public MyAdapter(Context context, List<ItemModel> itemList) {
        this.context = context;
        this.itemList = itemList;
        inflater = LayoutInflater.from(context);
    }

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

    @Override
    public Object getItem(int position) {
        return itemList.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.item_layout, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.title = convertView.findViewById(R.id.item_title);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        viewHolder.title.setText(itemList.get(position).getTitle());
        return convertView;
    }

    static class ViewHolder {
        TextView title;
    }
}

3. 創建一個緩存管理器類（CacheManager）：

public class CacheManager {
    private static final int MAX_CACHE_SIZE = 10;
    private LruCache<String, List<ItemModel>> cache;

    public CacheManager() {
        cache = new LruCache<String, List<ItemModel>>(MAX_CACHE_SIZE);
    }

    public List<ItemModel> getCache(String key) {
        return cache.get(key);
    }

    public void putCache(String key, List<ItemModel> itemList) {
        if (cache.size() >= MAX_CACHE_SIZE) {
            cache.evictAll();
        }
        cache.put(key, itemList);
    }
}

4. 在Activity中實現GridView分頁與緩存結合：

public class MainActivity extends AppCompatActivity {
    private GridView gridView;
    private MyAdapter adapter;
    private CacheManager cacheManager;
    private int currentPage = 1;
    private final int PAGE_SIZE = 20;

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

        gridView = findViewById(R.id.gridview);
        cacheManager = new CacheManager();
        adapter = new MyAdapter(this, getItemList(currentPage));
        gridView.setAdapter(adapter);

        gridView.setOnItemClickListener((parent, view, position, id) -> {
            // 處理點擊事件
        });

        loadMoreItems();
    }

    private List<ItemModel> getItemList(int page) {
        String cacheKey = "page_" + page;
        List<ItemModel> itemList = cacheManager.getCache(cacheKey);
        if (itemList == null) {
            // 從服務器或其他數據源獲取數據
            itemList = fetchItemsFromServer(page, PAGE_SIZE);
            cacheManager.putCache(cacheKey, itemList);
        }
        return itemList;
    }

    private List<ItemModel> fetchItemsFromServer(int page, int pageSize) {
        // 實現從服務器獲取數據的邏輯
        // 返回一個包含ItemModel對象的列表
    }

    private void loadMoreItems() {
        currentPage++;
        List<ItemModel> itemList = getItemList(currentPage);
        adapter.notifyDataSetChanged();
    }
}

在這個示例中，我們使用了LruCache作為緩存管理器，它會根據大小自動清理緩存。當用戶滾動GridView時，我們會加載更多數據并更新適配器。同時，我們會檢查緩存中是否已經存在數據，如果存在則直接使用緩存數據，否則從服務器或其他數據源獲取數據并更新緩存。