Android上在两个Activity之间传递Bitmap对象

转自：http://blog.csdn.net/jia20003/article/details/50212195

Android上在两个Activity之间传递Bitmap对象

因为我做Android应用的时间不长，所以当我第一次在android之间传递Bitmap对象的时候我直接用了Intent.putExtra的方法实现了，当时我选择的是一张图像的ROI区域，所以工作的很好，但是当我尝试将整个图片做为Bitmap对象传到另外一个Activity中的时候总是得到一个错误fatal bind error我当时很郁闷了好久，后来google才发现是这样传递Bitmap对象的方式不对，Activity之间传递Bitmap有大小限制，而且这个大小限制很小，512x512的图片肯定会得到我上述的这个错误，于是我想到了先保存到SD卡上然后传递路径的方法，但是SD卡属于外部存储，可能不是特别方便，后来看到有人通过内部存储方式实现了在两个Activity之间传递Bitmap对象以及其它支持串行化的Java对象，我觉得很好，所以就写了这篇博客。关键点有如下：

1．  HTTP客户端下载图片，通过ImageView对象显示

2．  把ImageView上的Bitmap对象从当前Activity传递到另外一个

Activity中并显示出来

3．  基于串行化传递Java对象数据

 

首先看我是怎么实现HTTP客户端下载图片，通过异步Task接口实现HTTP客户端下载图片并通过Handler来更新ImageView，代码如下：

 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 {
     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;
     }

 }

在当前的Activity中通过按钮上的事件响应实现切换View到对应的Activity中去，同时实现Java串行化数据传递。MainActivity的代码如下：

 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)
                 {
                     /*
                     // 为防止原始图片过大导致内存溢出，这里先缩小原图显示，然后释放原始Bitmap占用的内存
                     Bitmap smallBitmap = zoomBitmap(bitmap, bitmap.getWidth()/ 5, bitmap.getHeight() / 5);
                     // 释放资源
                     bitmap.recycle();
                     // 显示图片
                     imageView.setImageBitmap(smallBitmap);
                     imageView.invalidate();
                     */
                     imageView.setImageBitmap(bitmap);
                 }
             }
         };
         ImageLoadTask task = new ImageLoadTask(handler);
         task.execute("https://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); // 不改变原来图像大小
         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", "超级大美女");
             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("超级大美女");
             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;
     }
 }

对应另外一个Activity中实现读取与组装Bitmap对象显示的代码如下：

 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("名称: " + 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("名称: " + name);
         }
         if(description != null)
         {
             text2.setText("描述: " + description);
         }
     }

 }

对应的Java串行化对象类代码如下：

 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;

 }

最后声明：

别忘记在Manifest文件添加网络访问的权限

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

第一个按钮【传递图片】将会演示我遇到错误，第二按钮【传递文本数据】

将会演示正确的处理结果，显示如下：

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