Android处理Bit图片的几个函数分享

最近学习Android开发，发现图片处理很常用，特依据下载的各类代码，提取了几个不错的图片处理函数。

读取本地资源的图片的方法如下：

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);
	}

等比例压缩图片的函数封装如下：

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卡的代码：

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卡图片的方法如下：

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;
	}

头文件引入如下：

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;