圖片快取框架Picasso的學習和使用
阿新 • • 發佈：2018-12-21
搞Android的都知道對圖片的下載和快取處理非常的麻煩至極，動不動就發生OOM之類的情況。特別是在Listview，GridView，ViewPage等控制元件裡面。至此介紹Picasso圖片快取框架使用。相對ImageLoad等框架更為方便快速開發者使用。介紹下Picasso;
Picasso是Square公司開源的一個Android圖形快取庫，地址http://square.github.io/picasso/，可以實現圖片下載和快取功能。僅僅只需要一行程式碼就能完全實現圖片的非同步載入。
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
Picasso不僅實現了圖片非同步載入的功能，還解決了android中載入圖片時需要解決的一些常見問題：
1.在adapter中需要取消已經不在視野範圍的ImageView圖片資源的載入，否則會導致圖片錯位，Picasso已經解決了這個問題。
2.使用複雜的圖片壓縮轉換來儘可能的減少記憶體消耗
3.自帶記憶體和硬碟二級快取功能。
下面分別附上Eclipse的使用JAR包和Android Studio使用的gradle
jar包地址：http://download.csdn.net/detail/ae_fring/9624010
Studio：compile 'com.squareup.picasso:picasso:2.5.2'程式碼部分我就分享使用studio寫的：使用ListView展示訪問網路圖片並且快取起來使用。
請求網路資料我使用了xutils3.3.36。
Studio：compile 'org.xutils:xutils:3.3.36'
MainActivity頁面
@ContentView(R.layout.activity_main) public class MainActivity extends Activity { @ViewInject(R.id.lv) private ListView lv; private PicassoAdapter adapter; @ViewInject(R.id.cache_tv) private TextView cache_tv; /** * 獲取資料的介面 */ private String[] data = { "http://img3.redocn.com/20101213/20101211_0e830c2124ac3d92718fXrUdsYf49nDl.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383291_6518.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383291_8239.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383290_9329.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383290_1042.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383275_3977.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383265_8550.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383264_3954.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383264_4787.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383264_8243.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383248_3693.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383243_5120.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383242_3127.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383242_9576.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383242_1721.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383219_5806.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383214_7794.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383213_4418.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383213_3557.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383210_8779.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383172_4577.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383166_3407.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383166_2224.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383166_7301.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383165_7197.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383150_8410.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383131_3736.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383130_5094.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383130_7393.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383129_8813.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383100_3554.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383093_7894.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383092_2432.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383092_3071.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383091_3119.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383059_6589.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383059_8814.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383059_2237.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383058_4330.jpg", "http://img.my.csdn.net/uploads/201407/26/1406383038_3602.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382942_3079.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382942_8125.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382942_4881.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382941_4559.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382941_3845.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382924_8955.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382923_2141.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382923_8437.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382922_6166.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382922_4843.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382905_5804.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382904_3362.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382904_2312.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382904_4960.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382900_2418.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382881_4490.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382881_5935.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382880_3865.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382880_4662.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382879_2553.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382862_5375.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382862_1748.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382861_7618.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382861_8606.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382861_8949.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382841_9821.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382840_6603.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382840_2405.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382840_6354.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382839_5779.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382810_7578.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382810_2436.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382809_3883.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382809_6269.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382808_4179.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382790_8326.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382789_7174.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382789_5170.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382789_4118.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382788_9532.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382767_3184.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382767_4772.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382766_4924.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382766_5762.jpg", "http://img.my.csdn.net/uploads/201407/26/1406382765_7341.jpg" }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); x.view().inject(this); adapter = new PicassoAdapter(MainActivity.this, data); lv.setAdapter(adapter); lv.setOnScrollListener(onScrollListener); cache_tv.setText(CacheClearUtilManager.getTotalCacheSize(MainActivity.this)); cache_tv.setOnClickListener(onclicklistener); } private View.OnClickListener onclicklistener = new View.OnClickListener() { @Override public void onClick(View v) { CacheClearUtilManager.clearPicassoAllCache(MainActivity.this); cache_tv.setText(CacheClearUtilManager.getTotalCacheSize(MainActivity.this)); } }; private AbsListView.OnScrollListener onScrollListener = new AbsListView.OnScrollListener() { @Override public void onScrollStateChanged(AbsListView view, int scrollState) { final Picasso picasso = Picasso.with(MainActivity.this); if (scrollState == SCROLL_STATE_IDLE || scrollState == SCROLL_STATE_TOUCH_SCROLL) { picasso.resumeTag(MainActivity.this); } else { picasso.pauseTag(MainActivity.this); } } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { } }; }
至於 Picasso我進行了一個簡單的封裝便於使用：
**
* Created by zqf on 2016/8/8.
*/
public class PicassoUtil {
/**
* 載入指定寬高的圖片
*
* @param context
* @param path
* @param width
* @param height
* @param imageView
*/
public static void loadImageWithSize(Context context, String path, int width, int height, int placeholderresId, int errorResId, ImageView imageView) {
Picasso.with(context).load(path).resize(width, height).centerCrop().placeholder(placeholderresId).error(errorResId).into(imageView);
}
public static void loadImageWithHodler(Context context, String path, int resId, ImageView imageView) {
Picasso.with(context).load(path).fit().placeholder(resId).into(imageView);
}
public static void loadImageWithCrop(Context context, String path, ImageView imageView) {
Picasso.with(context).load(path).transform(new CustomImageCrop()).into(imageView);
}
/**
* 實現自定義圖片裁剪
*/
private static class CustomImageCrop implements Transformation {
@Override
public Bitmap transform(Bitmap source) {
int size = Math.min(source.getWidth(), source.getHeight());
int x = (source.getWidth() - size) / 2;
int y = (source.getHeight() - size) / 2;
Bitmap result = Bitmap.createBitmap(source, x, y, size, size);
if (result == null) {
result.recycle();
}
return result;
}
@Override
public String key() {
return "square()";
}
}
}介面卡頁面：
/**
* Created by zqf on 2016/8/7.
*/
public class PicassoAdapter extends BaseAdapter {
private LayoutInflater inflater;
private String[] data;
private Context context;
public PicassoAdapter(Context context, String[] data) {
this.data = data;
this.inflater = LayoutInflater.from(context);
this.context = context;
}
@Override
public int getCount() {
return data.length;
}
@Override
public Object getItem(int position) {
return data[position];
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.item, null);
holder = new ViewHolder();
holder.iv = (ImageView) convertView.findViewById(R.id.iv);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
PicassoUtil.loadImageWithSize(context, data[position], 100, 100, R.mipmap.ic_launcher, R.mipmap.ic_launcher, holder.iv);
return convertView;
}
private class ViewHolder {
ImageView iv;
}
}是不是感覺到了非常簡單，就幾行程式碼完全搞定了。訪問起來流暢並不會出現卡頓現象。如果覺得想試試趕緊試試吧！
當然了有寫的不好的各位見諒，歡迎指出。