Android上在两个Activity之间传递Bitmap对象

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<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);}@Overrideprotected Bitmap doInBackground(String... urls) {Bitmap bitmap = null;// create HTTP clientHttpClient httpclient = new DefaultHttpClient();try {// GET requestLog.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 responseHttpEntity httpEntity = httpResponse.getEntity();// read streamInputStream 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;@Overrideprotected 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;}@Overridepublic 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 URIImageInfoBean 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 {@Overrideprotected 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(); // refreshtext1.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：

Android上在两个Activity之间传递Bitmap对象_第2张图片

作者：jia20003 发表于2015/12/7 23:22:53 原文链接阅读：143 评论：0 查看评论

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