# 第一权限
<uses-permission android:name="android.permission.INTERNET"></uses-permission> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
第二 MD5工具类
public class EncoderUtils { /** * Md5Encoder * * @param string * @return * @throws Exception */ public static String encode(String string) throws Exception { byte[] hash = MessageDigest.getInstance("MD5").digest( string.getBytes("UTF-8")); StringBuilder hex = new StringBuilder(hash.length * 2); for (byte b : hash) { if ((b & 0xFF) < 0x10) { hex.append("0"); } hex.append(Integer.toHexString(b & 0xFF)); } return hex.toString(); } }
第三 图片缓存工具类
public class ImagesUtils { Handler handler; private File cacheDir; private ExecutorService newFixedThreadPool; private LruCache<String, Bitmap> lruCache; public ImagesUtils(Context context, Handler handler) { //获得你手机上的最大内存 long maxMemory = Runtime.getRuntime().maxMemory(); int maxSize = (int) (maxMemory/10); this.handler = handler; lruCache = new LruCache<String, Bitmap>(maxSize){ @Override protected int sizeOf(String key, Bitmap value) { return value.getRowBytes()*value.getHeight(); } }; //得到sd文件夹 cacheDir = context.getCacheDir(); // newFixedThreadPool = Executors.newFixedThreadPool(5); } public Bitmap getBitMap(String path){ Bitmap bitmap = lruCache.get(path); if(bitmap!=null){ System.out.println("我走了内存"); return bitmap; } //从本直去取,sd卡去取bitmap bitmap = getBitMapFromLocal(path); if(bitmap!=null){ System.out.println("我走了本地缓存"); return bitmap; } // 从网络去取 getBitmapFromNet(path); return null; } /** * 从网络 * * @param path */ private void getBitmapFromNet(final String path) { newFixedThreadPool.execute(new Runnable() { @Override public void run() { try { URL url = new URL(path); HttpURLConnection connection = (HttpURLConnection) url .openConnection(); connection.setConnectTimeout(5000); connection.setReadTimeout(5000); int responseCode = connection.getResponseCode(); if (responseCode == 200) { InputStream inputStream = connection.getInputStream(); Bitmap bitmap = BitmapFactory.decodeStream(inputStream); Message msg = new Message(); msg.what = 111; msg.obj = bitmap; Bundle data = new Bundle(); data.putString("tag", path); msg.setData(data); handler.sendMessage(msg); //缓存到本地 saveBitmapToLocal(bitmap, path); //缓存到内存 lruCache.put(path, bitmap); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }); } protected void saveBitmapToLocal(Bitmap bitmap, String path) { try { String encode = EncoderUtils.encode(path); FileOutputStream fileOutputStream = new FileOutputStream(cacheDir + "/" + encode); //图片二次裁剪 bitmap.compress(CompressFormat.JPEG, 80, fileOutputStream); } catch (Exception e) { e.printStackTrace(); } } /** * 从本地取 Md5 a.jpg b.jpg * aafdgsgsgsggg.jpg * @param path */ private Bitmap getBitMapFromLocal(String path) { try { String encode = EncoderUtils.encode(path); FileInputStream fileInputStream = new FileInputStream(cacheDir + "/" + encode); Bitmap bitmap = BitmapFactory.decodeStream(fileInputStream); //存到内存 lruCache.put(path, bitmap); return bitmap; } catch (Exception e) { e.printStackTrace(); } return null; } }
第四 主页 Activity
public class MainActivity extends AppCompatActivity { private GridView gv; ImagesUtils imags; String[] imageUrls = new String[] { "https://img-my.youkuaiyun.com/uploads/201407/26/1406383299_1976.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383291_6518.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383291_8239.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383290_9329.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383290_1042.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383275_3977.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383265_8550.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383264_3954.jpg", "https://img-my.youkuaiyun.com/uploads/201407/26/1406383264_4787.jpg", }; private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { super.handleMessage(msg); if (msg.what == 0) { Bitmap bitmap = (Bitmap) msg.obj; // 设置给imageView String tag = msg.getData().getString("tag"); // 根据标记取出imageView ImageView imageView = (ImageView) gv.findViewWithTag(tag); if (imageView != null && bitmap != null) { // 从网络获取图片 imageView.setImageBitmap(bitmap); Log.i("tag", "从网络中获取图片"); } } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); imags = new ImagesUtils(this,handler); gv = (GridView) findViewById(R.id.gv); gv.setAdapter(new MyAdapter()); } class MyAdapter extends BaseAdapter { @Override public int getCount() { // TODO Auto-generated method stub return imageUrls.length; } @Override public Object getItem(int position) { // TODO Auto-generated method stub return null; } @Override public long getItemId(int position) { // TODO Auto-generated method stub return 0; } @Override public View getView(int position, View convertView, ViewGroup parent) { ImageView iv = new ImageView(MainActivity.this); iv.setTag(imageUrls[position]); Bitmap bitmap = imags.getBitMap(imageUrls[position]); // 从内存中或者缓存中 if (bitmap != null) { iv.setImageBitmap(bitmap); } // 获取图片 return iv; } } }
第五 布局
<GridView android:id="@+id/gv" android:numColumns="3" android:layout_width="match_parent" android:layout_height="match_parent" />