安卓中关于图片从网络获取，压缩，上传，下载，缩略图，缓存的一些处理总结（二）

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第二部分：图片的压缩，缩略图的处理

继续上次说道的 从拍照或者相册中拿到了图片的地址或者URL，想上传到服务器，应该使之成为文件File，然后进行上传，上传服务器应进行压缩。否则服务器的压力和上传速度都会下降。当然如果有特殊的需求，可根据情况而定。

1.图片地址path 和 文件File 以及Bitmap之间的相互转化方法可自行查找。

public static void getBitmapForImgResourse(Context mContext, int imgId, ImageView mImageView) throws IOException {        InputStream is = mContext.getResources().openRawResource(imgId);        BitmapFactory.Options options = new BitmapFactory.Options();        options.inJustDecodeBounds = false;        options.inPreferredConfig = Bitmap.Config.RGB_565;        options.inPurgeable = true;        options.inInputShareable = true;        options.inSampleSize = 1;        btp = BitmapFactory.decodeStream(is, null, options);        mImageView.setImageBitmap(btp);//    btp.recycle();        is.close();    }

/** * 得到本地或者网络上的bitmap url - 网络或者本地图片的绝对路径,比如: * * A.网络路径: url="http://blog.foreverlove.us/girl2.png" ; * * B.本地路径:url="file://mnt/sdcard/photo/image.png"; * * C.支持的图片格式 ,png, jpg,bmp,gif等等 * * @param url * @return */public static Bitmap GetLocalOrNetBitmap(String url){    Bitmap bitmap = null;    InputStream in = null;    BufferedOutputStream out = null;    try    {        in = new BufferedInputStream(new URL(url).openStream(), 10*1024);        final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();        out = new BufferedOutputStream(dataStream, 10*1024);        copy(in, out);        out.flush();        byte[] data = dataStream.toByteArray();        bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);        data = null;        return bitmap;    }    catch (IOException e)    {        e.printStackTrace();        return null;    }}

。。。

2.图片的压缩

先说从体积上的压缩。如：3000K 压缩到300K

/** * 图像压缩算法 * * @param bmp     图片Bitmap * @param path    路径 * @param quality 压缩比例  100 最为清晰 压缩力度最小   0压缩力度最大 * @return 返回压缩之后的文件 */public static File compressBmpToFile(Bitmap bmp, String path, int quality) {    File file = new File(path);    Bitmap.CompressFormat format = Bitmap.CompressFormat.JPEG;    OutputStream stream = null;    try {        stream = new FileOutputStream(path);        bmp.compress(format, quality, stream);    } catch (FileNotFoundException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }    return file;}

当然如果你局的清晰度100 还是不行的话 写100以上也是不起作用的 可以参看源码

/** * Write a compressed version of the bitmap to the specified outputstream. * If this returns true, the bitmap can be reconstructed by passing a * corresponding inputstream to BitmapFactory.decodeStream(). Note: not * all Formats support all bitmap configs directly, so it is possible that * the returned bitmap from BitmapFactory could be in a different bitdepth, * and/or may have lost per-pixel alpha (e.g. JPEG only supports opaque * pixels). * * @param format   The format of the compressed image * @param quality  Hint to the compressor, 0-100. 0 meaning compress for *                 small size, 100 meaning compress for max quality. Some *                 formats, like PNG which is lossless, will ignore the *                 quality setting * @param stream   The outputstream to write the compressed data. * @return true if successfully compressed to the specified stream. */public boolean compress(CompressFormat format, int quality, OutputStream stream) {    checkRecycled("Can't compress a recycled bitmap");    // do explicit check before calling the native method    if (stream == null) {        throw new NullPointerException();    }    if (quality < 0 || quality > 100) {        throw new IllegalArgumentException("quality must be 0..100");  《《《《区间0-100    }    Trace.traceBegin(Trace.TRACE_TAG_RESOURCES, "Bitmap.compress");    boolean result = nativeCompress(mNativeBitmap, format.nativeInt, quality,                          stream, new byte[WORKING_COMPRESS_STORAGE]);    Trace.traceEnd(Trace.TRACE_TAG_RESOURCES);    return result;}

缩略图的处理 退出系统以后应该删除临时文件import java.io.BufferedInputStream;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.util.ArrayList;import java.util.List;import android.graphics.Bitmap;import android.graphics.BitmapFactory;public class Bimp {   public static int max = 0;   public static boolean act_bool = true;   public static List<Bitmap> bmp = new ArrayList<Bitmap>();   //图片sd地址  上传服务器时把图片调用下面方法压缩后 保存到临时文件夹 图片压缩后小于100KB，失真度不明显   public static List<String> drr = new ArrayList<String>();   public static Bitmap revitionImageSize(String path) throws IOException {      BufferedInputStream in = new BufferedInputStream(new FileInputStream(            new File(path)));      BitmapFactory.Options options = new BitmapFactory.Options();      options.inJustDecodeBounds = true;      BitmapFactory.decodeStream(in, null, options);      in.close();      int i = 0;      Bitmap bitmap = null;      while (true) {         if ((options.outWidth >> i <= 1000)               && (options.outHeight >> i <= 1000)) {            in = new BufferedInputStream(                  new FileInputStream(new File(path)));            options.inSampleSize = (int) Math.pow(2.0D, i);            options.inJustDecodeBounds = false;            bitmap = BitmapFactory.decodeStream(in, null, options);            break;         }         i += 1;      }      return bitmap;   }}
删除临时文件可以在生命周期销毁方法里写明清空。此略