Android传递Bitmap对象在两个Activity之间

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，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<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("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：