Android Bitmap转换

1、将Bitmap对象读到字节数组中

ByteArrayOutputStream baos = new ByteArrayOutputStream();  
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);  
byte[] datas = baos.toByteArray();  

2、将字节数组转为Bitmap对象

byte[] b = getIntent().getByteArrayExtra("bitmap");  
Bitmap bitmap = BitmapFactory.decodeByteArray(b, 0, b.length);  

3、图片文件转为Bitmap对象 

String filePath=”c:/01.jpg”;

Bitmap bitmap=BitmapFactory.decodeFile(filePath);

注：

如果图片过大，可能导致Bitmap对象装不下图片 
解决办法： 
String filePath=”c:/01.jpg”; 
Bitmap bitmap=BitmapFactory.decodeFile(filePath,getBitmapOption(2)); //将图片的长和宽缩小味原来的1/2

private Options getBitmapOption(int inSampleSize){ 
System.gc(); 
BitmapFactory.Options options = new BitmapFactory.Options(); 
options.inPurgeable = true; 
options.inSampleSize = inSampleSize; 
return options; 
}

4、Bitmap对象保存图片文件 

public void saveBitmapFile(Bitmap bitmap){ 
File file=new File(“/mnt/sdcard/pic/01.jpg”);//将要保存图片的路径 
try { 
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file)); 
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bos); 
bos.flush(); 
bos.close(); 
} catch (IOException e) { 
e.printStackTrace(); 
} 
}

5、bitmap和base64之间的转换

	/**
	 * bitmap转为base64
	 * @param bitmap
	 * @return
	 */
	public static String bitmapToBase64(Bitmap bitmap) {
 
		String result = null;
		ByteArrayOutputStream baos = null;
		try {
			if (bitmap != null) {
				baos = new ByteArrayOutputStream();
				bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
 
				baos.flush();
				baos.close();
 
				byte[] bitmapBytes = baos.toByteArray();
				result = Base64.encodeToString(bitmapBytes, Base64.DEFAULT);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if (baos != null) {
					baos.flush();
					baos.close();
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return result;
	}
 
	/**
	 * base64转为bitmap
	 * @param base64Data
	 * @return
	 */
	public static Bitmap base64ToBitmap(String base64Data) {
		byte[] bytes = Base64.decode(base64Data, Base64.DEFAULT);
		return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
	}

6、网络图片Url 转 Bitmap（须在子线程）

public Bitmap getBitmap(String url) {
        Bitmap bm = null;
        try {
            URL iconUrl = new URL(url);
            URLConnection conn = iconUrl.openConnection();
            HttpURLConnection http = (HttpURLConnection) conn;
            
            int length = http.getContentLength();
            
            conn.connect();
            // 获得图像的字符流
            InputStream is = conn.getInputStream();
            BufferedInputStream bis = new BufferedInputStream(is, length);
            bm = BitmapFactory.decodeStream(bis);
            bis.close();
            is.close();// 关闭流
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        return bm;
    }

7、将view转为bitmap

//1.0
public static Bitmap getBitmapFromView(View view)
{
    // Define a bitmap with the same size as the view
    Bitmap returnedBitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
    // Bind a canvas to it
    Canvas canvas = new Canvas(returnedBitmap);
    // Get the view's background
    Drawable bgDrawable = view.getBackground();
    if (bgDrawable != null)
        // has background drawable, then draw it on the canvas
        bgDrawable.draw(canvas);
    else
        // does not have background drawable, then draw white background on
        // the canvas
        canvas.drawColor(Color.WHITE);
    // draw the view on the canvas
    view.draw(canvas);
    // return the bitmap
    return returnedBitmap;
}

//2.0
public static Bitmap viewToBitmap(View view)
{
    view.setDrawingCacheEnabled(true);
    view.buildDrawingCache();
    Bitmap bm = view.getDrawingCache();
    return bm;
}

8、图片转为文件

public static boolean saveBitmap2file(Bitmap bmp)
{
    CompressFormat format = Bitmap.CompressFormat.PNG;
    int quality = 100;
    OutputStream stream = null;
    try
    {
        // 判断SDcard状态
        if (!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()))
        {
            // 错误提示
            return false;
        }
                                                                                                                                                                                                                                                                                                        
        // 检查SDcard空间
        File SDCardRoot = Environment.getExternalStorageDirectory();
        if (SDCardRoot.getFreeSpace() < 10000)
        {
            // 弹出对话框提示用户空间不够
            Log.e("Utils", "存储空间不够");
            return false;
        }
                                                                                                                                                                                                                                                                                                        
        // 在SDcard创建文件夹及文件
        File bitmapFile = new File(SDCardRoot.getPath() + FILE_PATH);
        bitmapFile.getParentFile().mkdirs();// 创建文件夹
        stream = new FileOutputStream(SDCardRoot.getPath() + FILE_PATH);// "/sdcard/"
    }
    catch (FileNotFoundException e)
    {
        e.printStackTrace();
    }
    return bmp.compress(format, quality, stream);
}