android图片的压缩和水印

学习了一下压缩和水印，以后要用到的时候可以直接来这里拷贝 
activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.bitmap_compress.MainActivity" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="match_parent"
        android:layout_height="300sp"
        android:contentDescription="@null"
        android:src="@drawable/a" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />

</LinearLayout>

MainActivity.Java

package com.example.bitmap_compress;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {
    private ImageView imageView;
    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //图片压缩
        imageView = (ImageView) findViewById(R.id.imageView1);
        Bitmap bitmap = BitmapCompressTools.decodeSampledBitmapFromResource(
                getResources(), R.drawable.a, 100, 100);
        Log.i("Original bytes",
                "----->>>"
                        + BitmapFactory.decodeResource(getResources(),
                                R.drawable.a).getByteCount());
        Log.i("Compressed bytes", "----->>>" + bitmap.getByteCount());
        imageView.setImageBitmap(bitmap);

        //水印，其实就是往图片上写字
        button = (Button) this.findViewById(R.id.button1);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Bitmap bitmap = BitmapTools.createBitmap(getResources(),
                        R.drawable.a, "a.png");
                imageView.setImageBitmap(bitmap);
            }
        });
    }
}

然后给出每个的工具类 
BitmapTools.java

package com.example.bitmap_compress;

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Environment;

public class BitmapTools {

    public static Bitmap createBitmap(Resources resources, int resid, String name) {
        Bitmap bitmap = BitmapFactory.decodeResource(resources, resid);
        // 复制一份新的Bitmap,因为不能直接在原有的bitmap上进行水印操作
        // Bitmap.config存储的格式
        Bitmap newBitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
        // 使用自定义画布
        Canvas canvas = new Canvas(newBitmap);
        Paint paint = new Paint();
        paint.setTextSize(200);
        canvas.drawText("hello", 100, 100, paint);
        // 判断SDcard是否在可用状态
        if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)) {
            // 直接将图片保存在根目录下
            File root = Environment.getExternalStorageDirectory();
            OutputStream outputStream = null;
            try {
                outputStream = new FileOutputStream(new File(root, name));
                // 对图片进行压缩并以png格式，保存在sdcard中
                newBitmap.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
            } catch (Exception e) {
            }
        }
        return newBitmap;
    }
}

BitmapCompressTools.java

package com.example.bitmap_compress;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

public class BitmapCompressTools {

    public static Bitmap decodeSampledBitmapFromResource(Resources resources,
            int resId, int width, int height) {
        // 给定的BitmapFactory设置解码的参数
        BitmapFactory.Options options = new BitmapFactory.Options();
        // 从解码器中获得原始图片的宽高，而避免申请内存空间
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(resources, resId, options);
        options.inSampleSize = calculateInSampleSize(options, width, height);
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(resources, resId, options);
    }

    /**
     * 指定输出图片的缩放比例
     * @param options
     * @param reqWidth
     * @param reqHeight
     * @return
     */
    public static int calculateInSampleSize(BitmapFactory.Options options,
            int reqWidth, int reqHeight) {
        // 获得原始图片的宽高
        int imageHeight = options.outHeight;
        int imageWidth = options.outWidth;
        int inSimpleSize = 1;
        if (imageHeight > reqHeight || imageWidth > reqWidth) {

            // 计算压缩的比例：分为宽高比例
            final int heightRatio = Math.round((float) imageHeight
                    / (float) reqHeight);
            final int widthRatio = Math.round((float) imageWidth
                    / (float) reqWidth);

            // Choose the smallest ratio as inSampleSize value, this will
            // guarantee
            // a final image with both dimensions larger than or equal to the
            // requested height and width.
            inSimpleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }
        return inSimpleSize;
    }
}