Android 图片的读取 缩放 保存

注意AndroidManifest配置权限：（在SD卡写入数据）

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

代码：

从另一个Activity 上传入byte型的数据，通过 bmp = BitmapFactory.decodeByteArray(txInfo, 0, txInfo.length);生成位图。

然后有用到ZoomControls图片缩放，最后可以保存图片到sd卡。

package com.login.main;    import java.io.File;  import java.io.FileNotFoundException;  import java.io.FileOutputStream;  import java.io.IOException;    import android.app.Activity;  import android.app.ProgressDialog;  import android.graphics.Bitmap;  import android.graphics.BitmapFactory;  import android.graphics.Matrix;  import android.os.Bundle;  import android.os.Handler;  import android.view.View;  import android.view.View.OnClickListener;  import android.widget.Button;  import android.widget.ImageView;  import android.widget.Toast;  import android.widget.ZoomControls;    public class List_tx extends Activity {     private ImageView imageView1;   private ZoomControls zoom;   private Button saveButton;   private float scaleWidth = 1;   private float scaleHeight = 1;   private Bitmap bmp;   private int zooms = 0;   private ProgressDialog m_Dialog = null;   private Handler handler = new Handler();   private String xh = "";     @Override   public void onCreate(Bundle savedInstanceState) {    // TODO Auto-generated method stub    super.onCreate(savedInstanceState);    setContentView(R.layout.list_tx);    Bundle b = this.getIntent().getExtras();    byte[] txInfo = b.getByteArray("txInfo");    xh = b.getString("xh");      saveButton = (Button) findViewById(R.id.saveButton);    saveButton.setOnClickListener(saveClick);    imageView1 = (ImageView) findViewById(R.id.imageView1);    bmp = BitmapFactory.decodeByteArray(txInfo, 0, txInfo.length);// 生成位图    imageView1.setImageBitmap(bmp);      zoom = (ZoomControls) findViewById(R.id.zoomcontrol);    zoom.setIsZoomInEnabled(true);    zoom.setIsZoomOutEnabled(true);      // 图片放大    zoom.setOnZoomInClickListener(new OnClickListener() {     public void onClick(View v) {      zoom.setIsZoomOutEnabled(true);      int bmpWidth = bmp.getWidth();      int bmpHeight = bmp.getHeight();      // 设置图片放大但比例      double scale = 1.25;      // 计算这次要放大的比例      if (zooms >= -3 && zooms < 6) {       scaleWidth = (float) (scaleWidth * scale);       scaleHeight = (float) (scaleHeight * scale);       // 产生新的大小但Bitmap对象       Matrix matrix = new Matrix();       matrix.postScale(scaleWidth, scaleHeight);       Bitmap resizeBmp = Bitmap.createBitmap(bmp, 0, 0, bmpWidth,         bmpHeight, matrix, true);       imageView1.setImageBitmap(resizeBmp);       zooms++;      } else       zoom.setIsZoomInEnabled(false);       }      });    // 图片减小    zoom.setOnZoomOutClickListener(new OnClickListener() {       public void onClick(View v) {      zoom.setIsZoomInEnabled(true);      int bmpWidth = bmp.getWidth();      int bmpHeight = bmp.getHeight();      // 设置图片放大但比例      double scale = 0.8;      // 计算这次要放大的比例      if (zooms > -3 && zooms <= 6) {       scaleWidth = (float) (scaleWidth * scale);       scaleHeight = (float) (scaleHeight * scale);       // 产生新的大小但Bitmap对象       Matrix matrix = new Matrix();       matrix.postScale(scaleWidth, scaleHeight);       Bitmap resizeBmp = Bitmap.createBitmap(bmp, 0, 0, bmpWidth,         bmpHeight, matrix, true);       imageView1.setImageBitmap(resizeBmp);       zooms--;      } else       zoom.setIsZoomOutEnabled(false);     }      });     }     // 保存   OnClickListener saveClick = new OnClickListener() {      public void onClick(final View v) {     m_Dialog = ProgressDialog.show(List_tx.this, "请稍后...", "图像保存中...",       true);       new Thread(new Runnable() {        public void run() {       File file = new File("/sdcard/" + xh + ".jpeg");       try {        FileOutputStream out = new FileOutputStream(file);        if (bmp.compress(Bitmap.CompressFormat.JPEG, 100, out)) {         out.flush();         out.close();        }       } catch (FileNotFoundException e) {        // TODO Auto-generated catch block        System.out.println("FileNotFoundException");        e.printStackTrace();       } catch (IOException e) {        // TODO Auto-generated catch block        System.out.println("FileNotFoundException");        e.printStackTrace();       }         // 更新界面       handler.post(new Runnable() {        public void run() {         Toast.makeText(getApplicationContext(),           "头像保存在" + "/sdcard/" + xh + ".jpeg",           Toast.LENGTH_SHORT).show();        }       });       m_Dialog.dismiss();      }     }).start();    }     };    }