直接上代码
ImageCache.java
public class ImageCache {
// 一级缓存 内部是LinkedHashMap
private LruCache<String, Bitmap> cache = null;
// 使用线程池
private ExecutorService threadPool = null;
private File localDir = null;
public ImageCache(Context context) {
threadPool = Executors.newFixedThreadPool(5);
localDir = context.getCacheDir();// 缓存目录
// 1/8 100M
long maxSize = Runtime.getRuntime().maxMemory() / 8;
// 图片大小
cache = new LruCache<String, Bitmap>((int) maxSize) {
// 图片大小的计算规则
@Override
protected int sizeOf(String key, Bitmap value) {
// // TODO Auto-generated method stub
// return super.sizeOf(key, value);
int bytesRow = value.getRowBytes();
int rowCount = value.getHeight();
return bytesRow * rowCount;
}
};
}
// http://a.hiphotos.baidu.com/image/w%3D310/sign=35424e84143853438ccf8120a312b01f/e61190ef76c6a7efce7315cef9faaf51f2de6684.jpg
public void disPlayImage(ImageView imageView, String url) {
//
// ① 访问 集合 HashMap<url,Bitmap> 比LinkedhashMap LRUCache 设计最大值 100M(
// 超过设置内存 丢弃 访问比较少的图片 )
// ② 访问sd/cache
// ③ 访问 网络
Bitmap bitmap = getFromCache(url);
if (bitmap != null) {
Log.i("wzx", "从内存取得图片");
imageView.setImageBitmap(bitmap);
return;
}
bitmap = getFromLocal(url);
if (bitmap != null) {
Log.i("wzx", "从本地取得图片");
imageView.setImageBitmap(bitmap);
return;
}
getFromNet(imageView, url);
return;
}
private class ImageRunnable implements Runnable {
private String url;
private ImageView imageView;
public ImageRunnable(ImageView imageView, String url) {
super();
this.imageView = imageView;
this.url = url;
}
@Override
public void run() {
try {
// TODO Auto-generated method stub
// 在线程内存访问网络 HttpURLConnection
// 拿到一个流
URL urlObj = new URL(url);
// 生成Bitmap
HttpURLConnection conn = (HttpURLConnection) urlObj.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
if (200 == conn.getResponseCode()) {
InputStream input = conn.getInputStream();
// 使用工具快速生成bitmap对象
byte[] bytes = StreamUtils.readInputStream(input);
// Bitmap bitmap = BitmapFactory.decodeStream(input);
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
if (bitmap != null) {
Message msg = new Message();
msg.what = 200;
HashMap<String, Object> data = new HashMap<String, Object>();
data.put("imagview", imageView);// 停止出现图片错乱问题
data.put("bitmap", bitmap);
msg.obj = data;
handler.sendMessage(msg);// -->handlemesssage();
// Log.i("wzx", "imageview");
// Log.i("wzx", "gridview");
// Log.i("wzx", "listview");
// 保存到集合
cache.put(url, bitmap);
// 保存到文件目录
writeToLocal(url, bitmap);
}
return;
}
} catch (Exception e) {
// TODO: handle exception
}
Message msg = new Message();
msg.what = 404;
handler.sendMessage(msg);
}
}
private Handler handler = new Handler() {
public void handleMessage(Message msg) {
if (msg.what == 200) {
HashMap<String, Object> data = (HashMap<String, Object>) msg.obj;
ImageView imageView = (ImageView) data.get("imagview");
Bitmap bitmap = (Bitmap) data.get("bitmap");
imageView.setImageBitmap(bitmap);
}
};
};
// 把图片保存成文件
private void writeToLocal(String url, Bitmap bitmap) {
try {
String rightFileName = URLEncoder.encode(url, "utf-8");
File imgeFile = new File(localDir.getAbsolutePath() + "/" + rightFileName);
if (!imgeFile.exists()) {
imgeFile.createNewFile();
}
// 打开一个输出流 往里面写数据
FileOutputStream fos = new FileOutputStream(imgeFile);
// bitmap.compress(格式 jpg png, quality, 输出流);//将图片数据写入到一个文件输出流
bitmap.compress(CompressFormat.JPEG, 80, fos);// 将图片数据写入到一个文件输出流
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private void getFromNet(ImageView imageView, String url) {
ImageRunnable r = new ImageRunnable(imageView, url);
// 获 取一个线程
threadPool.execute(r);
}
// 从本地文件获取图片
private Bitmap getFromLocal(String url) {
// data/data/包名/cache
// linux http://www.baidu.com/1.jpg
try {// %ss%dd
String rightFileName = URLEncoder.encode(url, "utf-8");
File imgeFile = new File(localDir.getAbsolutePath() + "/" + rightFileName);
// 使用图片工具类 BitmapFratory 将文件转换成图片
Bitmap bitmap = BitmapFactory.decodeFile(imgeFile.getAbsolutePath());
// 为了下次访问提高速度 添加到集合中
cache.put(url, bitmap);
return bitmap;
} catch (Exception e) {
// TODO: handle exception
}
return null;
}
// 从集合取
private Bitmap getFromCache(String url) {
return cache.get(url);
}
}
StreamUtils
public class StreamUtils {
/**
* 把一个流里面的内容 转化成一个字符串
*
* @param is
* 流里面的内容
* @return null解析失败
*/
public static String readStream(InputStream is) {
try {
byte[] bytes = readInputStream(is);
return new String(bytes);
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
public static byte[] readInputStream(InputStream is) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = -1;
while ((len = is.read(buffer)) != -1) {
baos.write(buffer, 0, len);
}
is.close();
return baos.toByteArray();
}
}
MainActivity
public class MainActivity extends Activity {
String url1 = "https://ss0.baidu.com/7Po3dSag_xI4khGko9WTAnF6hhy/image/h%3D300/sign=ada3d2a50cd162d99aee641c21dea950/b7003af33a87e9509a816f0d16385343fbf2b439.jpg";
String url2 = "https://ss1.baidu.com/9vo3dSag_xI4khGko9WTAnF6hhy/image/h%3D200/sign=e3cf61f8ba096b639e1959503c328733/203fb80e7bec54e7df58bcc9bd389b504ec26ab5.jpg";
String url3 = "https://ss1.baidu.com/-4o3dSag_xI4khGko9WTAnF6hhy/image/h%3D200/sign=1ee684a4e6fe9925d40c6e5004a95ee4/8694a4c27d1ed21b2a3bb284ab6eddc450da3fe4.jpg";
ImageView img1;
ImageView img2;
ImageView img3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
img1 = (ImageView) findViewById(R.id.img1);
img2 = (ImageView) findViewById(R.id.img2);
img3 = (ImageView) findViewById(R.id.img3);
ImageCache ic = new ImageCache(getBaseContext());
ic.disPlayImage(img1, url1);
ic.disPlayImage(img2, url2);
ic.disPlayImage(img3, url3);
}
}
