<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.weima.MainActivity" >

     <EditText
        android:id="@+id/editText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="38dp"
        android:layout_marginTop="33dp"
        android:ems="10" >

        <requestFocus />
    </EditText>
    
   <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/editText1"
        android:layout_below="@+id/editText1"
        android:layout_marginRight="20dp"
        android:layout_marginTop="22dp"
        android:text="Button" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/editText1"
        android:layout_below="@+id/button1"
        android:layout_marginLeft="14dp"
        android:layout_marginTop="47dp" />
    
</RelativeLayout>

public class MainActivity extends Activity {

    private EditText ent;
    private Button btn;
    private ImageView img;
    private static final int IMAGE_HALFWIDTH = 35;//图片宽度值大小
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        ent=(EditText)findViewById(R.id.editText1);
        img=(ImageView)findViewById(R.id.imageView1);
        btn=(Button)findViewById(R.id.button1);
        btn.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                //取出字符串
                String entText=ent.getText().toString();
                Bitmap log=BitmapFactory.decodeResource(getResources(), R.drawable.weixintubiao);
                
                try {
                    Bitmap bm=createCode(entText,log,BarcodeFormat.QR_CODE);
                    img.setImageBitmap(bm);
                } catch (WriterException e) {
                    e.printStackTrace();
                }
            }});
    }

    public Bitmap createCode(String string,Bitmap mBitmap, BarcodeFormat format)throws WriterException
    {
        
        //Matrix，中文里叫矩阵，在图像处理方面，主要是用于平面的缩放、平移、旋转等操作。
        Matrix mat=new Matrix();
        float imgX=(float)2*IMAGE_HALFWIDTH/mBitmap.getWidth();
        float imgY=(float)2*IMAGE_HALFWIDTH/mBitmap.getHeight();
        mat.setScale(imgX,imgY);//设置缩放信息
        //将logo图片按martix设置的信息缩放
        mBitmap = Bitmap.createBitmap(mBitmap, 0, 0,mBitmap.getWidth(), mBitmap.getHeight(), mat, false);
        MultiFormatWriter writer=new MultiFormatWriter();
        Hashtable htable=new Hashtable();
        htable.put(EncodeHintType.CHARACTER_SET, "UTF-8");//设置字符编码
        //生成二维码矩阵信息
        BitMatrix matrix = writer.encode(string, format, 800, 800, htable);
        int width=matrix.getWidth();//矩阵宽度
        int height=matrix.getHeight();//矩阵高度
        int matW=width/2;
        int matH=height/2;
        int[] pixels = new int[width * height];//定义数组长度为矩阵高度*矩阵宽度，用于记录矩阵中像素信息
        for(int y=0;y<height;y++){//从行开始迭代矩阵
        for(int x=0;x<width;x++)//迭代列
        {
            if (x > matW - IMAGE_HALFWIDTH && x < matW + IMAGE_HALFWIDTH && y > matH - IMAGE_HALFWIDTH && y < matH + IMAGE_HALFWIDTH) {
                //该位置用于存放图片信息
                //记录图片每个像素信息
                pixels[y * width + x] = mBitmap.getPixel(x - matW+ IMAGE_HALFWIDTH, y - matH + IMAGE_HALFWIDTH); 
            }
            else {
                if (matrix.get(x, y)) {
                    //如果有黑块点，记录信息
                    pixels[y * width + x] = 0xff000000;//记录黑块信息
                }
            }
        }
    }
        Bitmap bitmap = Bitmap.createBitmap(width, height,Bitmap.Config.ARGB_8888);
        // 通过像素数组生成bitmap
        bitmap.setPixels(pixels, 0, width, 0, 0, width, height);
        return bitmap;
    }

   
}