Android傳遞Bitmap對象在兩個Activity之間_Android

通過內部儲存方式實現了在兩個Activity之間傳遞Bitmap對象以及其它支援序列化的Java對象，關鍵點有如下：

1．  HTTP用戶端下載圖片，通過ImageView對象顯示

2．  把ImageView上的Bitmap對象從當前Activity傳遞到另外一個Activity中並顯示出來

3．  基於序列化傳遞Java對象資料

首先看我是怎麼實現HTTP用戶端下載圖片，通過非同步Task介面實現HTTP用戶端下載圖片並通過Handler來更新ImageView，代碼如下：

package com.example.sharedemo;  import java.io.IOException; import java.io.InputStream;  import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient;  import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.AsyncTask; import android.os.Handler; import android.os.Message; import android.util.Log;  public class ImageLoadTask extends AsyncTask<String, Void, Bitmap> {   private Handler handler;    public ImageLoadTask(Handler handler) {     this.handler = handler;   }    protected void onPostExecute(Bitmap bitmap) {     Message msg = new Message();     msg.obj = bitmap;     handler.sendMessage(msg);   }    @Override   protected Bitmap doInBackground(String... urls) {     Bitmap bitmap = null;     // create HTTP client     HttpClient httpclient = new DefaultHttpClient();     try {       // GET request       Log.i("image-url", urls[0]);       HttpGet httpRequest = new HttpGet(urls[0]);       HttpResponse httpResponse = httpclient.execute(httpRequest);       if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {         // get entity from response         HttpEntity httpEntity = httpResponse.getEntity();         // read stream         InputStream is = httpEntity.getContent();         bitmap = BitmapFactory.decodeStream(is);         is.close();         Log.i("image", "already get the image by url : " + urls[0]);       }      } catch (ClientProtocolException e) {       e.printStackTrace();     } catch (IOException e) {       e.printStackTrace();     } finally {       httpclient.getConnectionManager().shutdown();     }     return bitmap;   }  } 

在當前的Activity中通過按鈕上的事件響應實現切換View到對應的Activity中去，同時實現Java序列化資料傳遞。MainActivity的代碼如下：

package com.example.sharedemo;  import java.io.ByteArrayOutputStream; import java.io.FileOutputStream;  import android.app.Activity; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.Matrix; import android.graphics.drawable.BitmapDrawable; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ImageView;  public class MainActivity extends Activity implements OnClickListener{   public final static String SHARE_BITMAP_COMMAND = "share-image";   public final static String SHARE_TEXT_DATA_COMMAND = "share-text-data";   private Handler handler;    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     setupOnClickListener();   }    private void setupOnClickListener() {     Button bitmapBtn = (Button)this.findViewById(R.id.bitmapShareBtn);     bitmapBtn.setTag(SHARE_BITMAP_COMMAND);     bitmapBtn.setOnClickListener(this);     Button textDataBtn = (Button)this.findViewById(R.id.mapShareBtn);     textDataBtn.setTag(SHARE_TEXT_DATA_COMMAND);     textDataBtn.setOnClickListener(this);     final ImageView imageView = (ImageView)this.findViewById(R.id.imageView1);          handler = new Handler()     {       public void handleMessage(Message msg) {         Bitmap bitmap = (Bitmap)msg.obj;         if(bitmap != null)         {           /*           // 為防止原始圖片過大導致記憶體溢出，這裡先縮小原圖顯示，然後釋放原始Bitmap佔用的記憶體           Bitmap smallBitmap = zoomBitmap(bitmap, bitmap.getWidth()/ 5, bitmap.getHeight() / 5);           // 釋放資源           bitmap.recycle();           // 顯示圖片           imageView.setImageBitmap(smallBitmap);           imageView.invalidate();           */           imageView.setImageBitmap(bitmap);         }       }     };     ImageLoadTask task = new ImageLoadTask(handler);     task.execute("http://img.blog.csdn.net/20150607143208238");   }      public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {     int w = bitmap.getWidth();     int h = bitmap.getHeight();     Matrix matrix = new Matrix();     float scaleWidth = ((float) width / w);     float scaleHeight = ((float) height / h);     matrix.postScale(scaleWidth, scaleHeight); // 不改變原來映像大小     Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);     return newbmp;   }    @Override   public void onClick(View v) {     Object tag = v.getTag();     Log.i("command", tag.toString());     if(SHARE_BITMAP_COMMAND.equals(tag))     {       Intent intent = new Intent(this.getApplicationContext(), ImageProcessActivity.class);       ImageView imageView = (ImageView)this.findViewById(R.id.imageView1);       Bitmap bitmap = ((BitmapDrawable)imageView.getDrawable()).getBitmap();       intent.putExtra("selectedImage", bitmap);       intent.putExtra("name", "lena");       intent.putExtra("description", "超級大美女");       this.startActivity(intent);          }     else if(SHARE_TEXT_DATA_COMMAND.equals(tag))     {       Intent intent = new Intent(this.getApplicationContext(), ImageProcessActivity.class);       ImageView imageView = (ImageView)this.findViewById(R.id.imageView1);       Bitmap bitmap = ((BitmapDrawable)imageView.getDrawable()).getBitmap();       // save it first then pass URI       ImageInfoBean dto = new ImageInfoBean();       String uri = createImageFromBitmap(bitmap);       dto.setDescription("超級大美女");       dto.setName("lena");       dto.setUri(uri);              intent.putExtra("tiger", dto);       this.startActivity(intent);      }   }      public String createImageFromBitmap(Bitmap bitmap) {     String fileName = "myImage";     try {       ByteArrayOutputStream bytes = new ByteArrayOutputStream();       bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bytes);       FileOutputStream fo = openFileOutput(fileName, Context.MODE_PRIVATE);       fo.write(bytes.toByteArray());       fo.close();     } catch (Exception e) {       e.printStackTrace();       fileName = null;     }     Log.i("fileName", fileName);     return fileName;   } } 

對應另外一個Activity中實現讀取與組裝Bitmap對象顯示的代碼如下：

package com.example.sharedemo;  import java.io.FileNotFoundException;  import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.widget.ImageView; import android.widget.TextView;  public class ImageProcessActivity extends Activity {    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.share_info);     backFillData();   }    private void backFillData() {     Object obj = this.getIntent().getExtras().get("tiger");     ImageView imageView = (ImageView)this.findViewById(R.id.imageView1);     TextView text1 = (TextView)this.findViewById(R.id.textView1);     TextView text2 = (TextView)this.findViewById(R.id.textView2);     try {       if(obj != null && obj instanceof ImageInfoBean)       {         ImageInfoBean dto = (ImageInfoBean)obj;         Bitmap bitmap = BitmapFactory.decodeStream(this.openFileInput(dto.getUri()));         imageView.setImageBitmap(bitmap);         imageView.invalidate(); // refresh                  text1.setText("名稱: " + dto.getName());         text2.setText("描述: " + dto.getDescription());         return;       }     } catch (FileNotFoundException e) {       e.printStackTrace();     }          Bitmap bitmap = (Bitmap) this.getIntent().getParcelableExtra("selectedImage");     String name = this.getIntent().getExtras().getString("name");     String description = this.getIntent().getExtras().getString("description");     if(bitmap != null)     {       imageView.setImageBitmap(bitmap);       imageView.invalidate(); // refresh     }     if(name != null)     {       text1.setText("名稱: " + name);     }     if(description != null)     {       text2.setText("描述: " + description);     }   }  } 

對應的Java序列化對象類代碼如下：

package com.example.sharedemo;  import java.io.Serializable;  public class ImageInfoBean implements Serializable {   /**    *    */   private static final long serialVersionUID = 1L;    public String getName() {     return name;   }    public void setName(String name) {     this.name = name;   }    public String getDescription() {     return description;   }    public void setDescription(String description) {     this.description = description;   }    public String getUri() {     return uri;   }    public void setUri(String uri) {     this.uri = uri;   }    private String name;   private String description;   private String uri;  } 

最後聲明：
別忘記在Manifest檔案添加網路訪問的許可權

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

第一個按鈕【傳遞圖片】將會示範我遇到錯誤，第二按鈕【傳遞文本資料】
將會示範正確的處理結果，顯示如下：

以上就是本文的全部內容，希望對大家的學習有所協助。