Android傳遞Bitmap對象在兩個Activity之間
通過內(nèi)部存儲方式實現(xiàn)了在兩個Activity之間傳遞Bitmap對象以及其它支持串行化的Java對象,關鍵點有如下:
1. HTTP客戶端下載圖片,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中并顯示出來
3. 基于串行化傳遞Java對象數(shù)據(jù)
首先看我是怎么實現(xiàn)HTTP客戶端下載圖片,通過異步Task接口實現(xiàn)HTTP客戶端下載圖片并通過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(xiàn)切換View到對應的Activity中去,同時實現(xiàn)Java串行化數(shù)據(jù)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內(nèi)存溢出,這里先縮小原圖顯示,然后釋放原始Bitmap占用的內(nèi)存
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); // 不改變原來圖像大小
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(xiàn)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串行化對象類代碼如下:
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;
}
最后聲明:
別忘記在Manifest文件添加網(wǎng)絡訪問的權(quán)限
<uses-permission android:name="android.permission.INTERNET"/>

第一個按鈕【傳遞圖片】將會演示我遇到錯誤,第二按鈕【傳遞文本數(shù)據(jù)】
將會演示正確的處理結(jié)果,顯示如下:

以上就是本文的全部內(nèi)容,希望對大家的學習有所幫助。
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