Android(安卓)图片Bitmap保存到内存卡
16lz
2021-01-25
一、什么是Android中的Bitmap
Bitmap是Android系统中的图像处理的最重要类之一。用它可以获取图像文件信息，进行图像剪切、旋转、缩放等操作，并可以指定格式保存图像文件。二、什么是内存卡
SD卡存储卡，是用于手机、数码相机、便携式电脑、MP3和其他数码产品上的独立存储介质，一般是卡片的形态，故统称为“存储卡”，又称为“数码存储卡”、“数字存储卡”、“储存卡”等。
三、图片为什么要存在内存卡里
部分手机的手机内存是不够的，一个程序如果产生的图片量太大，很容易占用了宝贵的手机内存，所以安全起见，图片最好存放在内存卡中
四、如何存放
import java.io.BufferedInputStream;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Environment;import android.os.StatFs;import android.util.Log;public class BitmaptoCard {private static int FREE_SD_SPACE_NEEDED_TO_CACHE = 1;private static int MB = 1024 * 1024;/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, Bitmap bm, String filename,int quantity, boolean recyle) {boolean ret = true;if (bm == null) {return false;}if (FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {bm.recycle();bm = null;return false;}File dirPath = new File(dir);if (!exists(dir)) {dirPath.mkdirs();}if (!dir.endsWith(File.separator)) {dir += File.separator;}File file = new File(dir + filename);OutputStream outStream = null;try {file.createNewFile();outStream = new FileOutputStream(file);bm.compress(Bitmap.CompressFormat.JPEG, quantity, outStream);outStream.flush();outStream.close();} catch (FileNotFoundException e) {e.printStackTrace();ret = false;} catch (IOException e) {e.printStackTrace();ret = false;} catch (OutOfMemoryError e) {e.printStackTrace();ret = false;} finally {if (outStream != null) {try {outStream.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if (recyle && !bm.isRecycled()) {bm.recycle();bm = null;Log.e("BitmaptoCard", "saveBmpToSd, recyle");}}return ret;}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, Bitmap bm, String filename,int quantity) {return saveBmpToSd(dir, bm, filename, quantity, false);}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, String srcFile,String filename, int quantity) {if (srcFile == null) {return false;}Bitmap bmp = BitmapFactory.decodeFile(srcFile);return saveBmpToSd(dir, bmp, filename, quantity);}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, String srcFile,String filename, int quantity, boolean recyle) {if (srcFile == null) {return false;}Bitmap bmp = BitmapFactory.decodeFile(srcFile);return saveBmpToSd(dir, bmp, filename, quantity, recyle);}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, String srcFile,String filename, int quantity, float size, boolean recyle) {if (srcFile == null) {return false;}Bitmap bmp = convertToThumb(readFileToBuffer(srcFile), size);return saveBmpToSd(dir, bmp, filename, quantity, recyle);}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, String srcFile,String filename, int quantity, float size) {if (srcFile == null) {return false;}Bitmap bmp = convertToThumb(readFileToBuffer(srcFile), size);return saveBmpToSd(dir, bmp, filename, quantity);}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String dir, Bitmap bmp, String filename,int quantity, float size) {if (bmp == null) {return false;}bmp = convertToThumb(readBitmap(bmp), size);return saveBmpToSd(dir, bmp, filename, quantity);}/** * 获取sdcard路径 * * @return */public static String getSdcardPath() {return Environment.getExternalStorageDirectory().getPath()+ File.separator;}/** * 验证文件是否存在 * * @param url * @return */public static boolean exists(String url) {File file = new File(url);return file.exists();}/** * 检测sdcard可用空间 * * @return */public static int freeSpaceOnSd() {StatFs stat = new StatFs(Environment.getExternalStorageDirectory().getPath());double sdFreeMB = ((double) stat.getAvailableBlocks() * (double) stat.getBlockSize()) / MB;return (int) sdFreeMB;}/** * Bitmap --> byte[] * * @param bmp * @return */private static byte[] readBitmap(Bitmap bmp) {ByteArrayOutputStream baos = new ByteArrayOutputStream();bmp.compress(Bitmap.CompressFormat.JPEG, 60, baos);try {baos.flush();baos.close();} catch (IOException e) {e.printStackTrace();}return baos.toByteArray();}/** * 保存Bitmap到sdcard * * @param dir * @param bm * @param filename * @param quantity */public static boolean saveBmpToSd(String filePath, Bitmap bm, int quantity) {if (filePath == null) {return false;}int end = filePath.lastIndexOf(File.separator);String dir = filePath.substring(0, end);String filename = filePath.substring(end);return saveBmpToSd(dir, bm, filename, quantity);}/** * @description: 通过文件路径将对应文件转为byte[] * @param fileName * @return */public static byte[] getByte(String fileName) {if (fileName == null || "".equals(fileName)) {return new byte[0];}File file = new File(fileName);if (file.exists()) {try {FileInputStream fin = new FileInputStream(fileName);int length = fin.available();byte[] buffer = new byte[length];fin.read(buffer);// res = EncodingUtils.getString(buffer, "UTF-8");fin.close();return buffer;} catch (Exception e) {Log.e("BitmaptoCard", "getByte fail:" + fileName);return new byte[0];}} else {Log.e("BitmaptoCard", "getByte file no exists :" + fileName);return new byte[0];}}/** * 将图片、语音或者文件读入到byte缓冲数组 * * @param filePath * @return */public static byte[] readFileToBuffer(String filePath) {if (filePath == null || filePath.trim().equals("")) {Log.e("BitmaptoCard", "readFileToBuffer, path is null:" + filePath);return null;}File file = new File(filePath);if (!file.exists()) {Log.e("BitmaptoCard", "readFileToBuffer, file is not exists:"+ filePath);return null;}byte[] buffer = new byte[(int) file.length()];FileInputStream fis = null;try {fis = new FileInputStream(file);BufferedInputStream bis = new BufferedInputStream(fis);bis.read(buffer);bis.close();} catch (Exception e) {e.printStackTrace();}return buffer;}/** * 检查图片是否超过一定值，是则缩小 * * @param view * @param strFileName */public static Bitmap convertToThumb(byte[] buffer, float size) {// 获取原图宽度BitmapFactory.Options options = new BitmapFactory.Options();options.inJustDecodeBounds = true;options.inPurgeable = true;options.inInputShareable = true;Bitmap bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length,options);// 计算缩放比例float reSize = options.outWidth / size;if (options.outWidth > options.outHeight) {reSize = options.outHeight / size;}if (reSize <= 0) {reSize = 1;}Log.d("BitmaptoCard", "convertToThumb, reSize:" + reSize);// 缩放options.inJustDecodeBounds = false;options.inSampleSize = (int) reSize;if (bm != null && !bm.isRecycled()) {bm.recycle();bm = null;Log.e("BitmaptoCard", "convertToThumb, recyle");}bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length, options);if (bm == null) {Log.e("BitmaptoCard", "convertToThumb, decode fail:" + null);return null;}return bm;}} 示例代码：http://download.csdn.net/detail/stop_pig/7162695
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