一、什麼是Android中的Bitmap
Bitmap是Android系統中的圖像處理的最重要類之一。用它可以擷取圖像檔案資訊，進行圖像剪切、旋轉、縮放等操作，并可以指定格式儲存圖像檔案。
二、什麼是記憶體卡
SD卡存儲卡，是用于手機、數位相機、便攜式電腦、MP3和其他數位産品上的獨立存儲媒體，一般是卡片的形态，故統稱為“存儲卡”，又稱為“數位存儲卡”、“數字存儲卡”、“儲存卡”等。
三、圖檔為什麼要存在記憶體卡裡
部分手機的手機記憶體是不夠的，一個程式如果産生的圖檔量太大，很容易占用了寶貴的手機記憶體，是以安全起見，圖檔最好存放在記憶體卡中
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;
/**
* 儲存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 block
e.printStackTrace();
}
}
if (recyle && !bm.isRecycled()) {
bm.recycle();
bm = null;
Log.e("BitmaptoCard", "saveBmpToSd, recyle");
}
}
return ret;
}
/**
* 儲存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);
}
/**
* 儲存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);
}
/**
* 儲存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);
}
/**
* 儲存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);
}
/**
* 儲存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);
}
/**
* 儲存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);
}
/**
* 擷取sdcard路徑
*
* @return
*/
public static String getSdcardPath() {
return Environment.getExternalStorageDirectory().getPath()
+ File.separator;
}
/**
* 驗證檔案是否存在
*
* @param url
* @return
*/
public static boolean exists(String url) {
File file = new File(url);
return file.exists();
}
/**
* 檢測sdcard可用空間
*
* @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();
}
/**
* 儲存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: 通過檔案路徑将對應檔案轉為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];
}
}
/**
* 将圖檔、語音或者檔案讀入到byte緩沖數組
*
* @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;
}
/**
* 檢查圖檔是否超過一定值，是則縮小
*
* @param view
* @param strFileName
*/
public static Bitmap convertToThumb(byte[] buffer, float size) {
// 擷取原圖寬度
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
options.inPurgeable = true;
options.inInputShareable = true;
Bitmap bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length,
options);
// 計算縮放比例
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);
// 縮放
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;
}
}
示例代碼：http://download.csdn.net/detail/stop_pig/7162695
![Android MVP架構MVCMVP[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)