android中位图Bitmap工具类的实现

android中位图工具类的实现：

package com.demo.utils;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.URL;import java.net.URLEncoder;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.BitmapFactory;import android.graphics.Matrix;import android.os.Environment;import android.os.StatFs;import android.util.Log;public class BitmapUtil {/** * 读取本地资源的图片 *  * @param context * @param resId * @return */public static Bitmap ReadBitmapById(Context context, int resId) {BitmapFactory.Options opt = new BitmapFactory.Options();opt.inPreferredConfig = Bitmap.Config.RGB_565;opt.inPurgeable = true;opt.inInputShareable = true;// 获取资源图片InputStream is = context.getResources().openRawResource(resId);return BitmapFactory.decodeStream(is, null, opt);}/*** * 根据资源文件获取Bitmap *  * @param context * @param drawableId * @return */public static Bitmap ReadBitmapById(Context context, int drawableId,int screenWidth, int screenHight) {BitmapFactory.Options options = new BitmapFactory.Options();options.inPreferredConfig = Config.ARGB_8888;options.inInputShareable = true;options.inPurgeable = true;InputStream stream = context.getResources().openRawResource(drawableId);Bitmap bitmap = BitmapFactory.decodeStream(stream, null, options);return getBitmap(bitmap, screenWidth, screenHight);}/*** * 等比例压缩图片 *  * @param bitmap * @param screenWidth * @param screenHight * @return */public static Bitmap getBitmap(Bitmap bitmap, int screenWidth,int screenHight) {int w = bitmap.getWidth();int h = bitmap.getHeight();Log.e("jj", "图片宽度" + w + ",screenWidth=" + screenWidth);Matrix matrix = new Matrix();float scale = (float) screenWidth / w;// float scale2 = (float) screenHight / h;// scale = scale < scale2 ? scale : scale2;// 保证图片不变形.matrix.postScale(scale, scale);// w,h是原图的属性.return Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);}/*** * 保存图片至SD卡 *  * @param bm * @param url * @param quantity */private static int FREE_SD_SPACE_NEEDED_TO_CACHE = 1;private static int MB = 1024 * 1024;public final static String DIR = "/sdcard/hypers";public static void saveBmpToSd(Bitmap bm, String url, int quantity) {// 判断sdcard上的空间if (FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {return;}if (!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()))return;String filename = url;// 目录不存在就创建File dirPath = new File(DIR);if (!dirPath.exists()) {dirPath.mkdirs();}File file = new File(DIR + "/" + filename);try {file.createNewFile();OutputStream outStream = new FileOutputStream(file);bm.compress(Bitmap.CompressFormat.PNG, quantity, outStream);outStream.flush();outStream.close();} catch (FileNotFoundException e) {} catch (IOException e) {e.printStackTrace();}}/*** * 获取SD卡图片 *  * @param url * @param quantity * @return */public static Bitmap GetBitmap(String url, int quantity) {InputStream inputStream = null;String filename = "";Bitmap map = null;URL url_Image = null;String LOCALURL = "";if (url == null)return null;try {filename = url;} catch (Exception err) {}LOCALURL = URLEncoder.encode(filename);if (Exist(DIR + "/" + LOCALURL)) {map = BitmapFactory.decodeFile(DIR + "/" + LOCALURL);} else {try {url_Image = new URL(url);inputStream = url_Image.openStream();map = BitmapFactory.decodeStream(inputStream);// url = URLEncoder.encode(url, "UTF-8");if (map != null) {saveBmpToSd(map, LOCALURL, quantity);}inputStream.close();} catch (Exception e) {e.printStackTrace();return null;}}return map;}/*** * 判断图片是存在 *  * @param url * @return */public static boolean Exist(String url) {File file = new File(DIR + url);return file.exists();}/** * 计算sdcard上的剩余空间 * @return */private static int freeSpaceOnSd() {StatFs stat = new StatFs(Environment.getExternalStorageDirectory().getPath());double sdFreeMB = ((double) stat.getAvailableBlocks() * (double) stat.getBlockSize()) / MB;return (int) sdFreeMB;}}