从系统中读取图片、照相，显示在屏幕上。整合Intent

《打造高质量的Android应用》 中的Hack35为主题，同时发起选择图片和拍照的Intent。然后我有加了一点内容，把图片显示出来。布局：3个Button，一个ImageView

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="整合两个Intent" />

    <Button 
        android:id="@+id/btn_1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="TakePicture"
        android:gravity="center"
        />
    <Button 
        android:id="@+id/btn_2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="PickPicture"
        android:gravity="cent
        />
    <Button 
        android:id="@+id/btn_3"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Both TakePicture  PickPicture"
        android:gravity="center"
        />
    <ImageView 
        android:id="@+id/iamge"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#fafafa" 
        android:scaleType="fitCenter"
        />
</LinearLayout>

MainActivity实现OnClickListener接口，OnClick方法：

<span style="white-space:pre">	</span>private static final int PICK_PICTURE = 10;<span style="white-space:pre">	</span>private static final int TAKE_PICTURE = 11;<span style="white-space:pre">	</span>private static final int PICK_OR_TAKE_PICTURE = 13;

@Override	public void onClick(View v) {		switch (v.getId()) {		case R.id.btn_1:			Intent takePhotoIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);			Intent chooserIntent1 = Intent.createChooser(takePhotoIntent, "Take picture");//用<span style="font-family: Arial, Helvetica, sans-serif;">MediaStore.ACTION_IMAGE_CAPTURE和</span><span style="font-family: Arial, Helvetica, sans-serif;"> "Take picture"两个参数对Intent进行修饰和约束，</span>			startActivityForResult(chooserIntent1, TAKE_PICTURE);			break;		case R.id.btn_2:			Intent pickIntent = new Intent(Intent.ACTION_GET_CONTENT);			pickIntent.setType("image/*");			pickIntent.putExtra("return-data", true);			Intent chooserIntent2 = Intent.createChooser(pickIntent, "Pick Pickture");			startActivityForResult(chooserIntent2, PICK_PICTURE);			break;		case R.id.btn_3:			Intent takePhotoIntent2 = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);						Intent pickIntent2 = new Intent(Intent.ACTION_GET_CONTENT);			pickIntent2.setType("image/*");						Intent chooserIntent3 = Intent.createChooser(pickIntent2, "Take or pick Picture");//这里先用<span style="font-family: Arial, Helvetica, sans-serif;">pickIntent2初始化了chooser,</span>			chooserIntent3.putExtra(Intent.EXTRA_INITIAL_INTENTS, new Intent[]{takePhotoIntent2});//在这里，用<span style="font-family: Arial, Helvetica, sans-serif;">Intent.EXTRA_INITIAL_INTENTS做第一个参数，第二个参数</span><span style="font-family: Arial, Helvetica, sans-serif;">new Intent[]{takePhotoIntent2}就是我们要添加进去的Intent</span>				startActivityForResult(chooserIntent3, PICK_OR_TAKE_PICTURE);	break;		default:			break;		}			}

比如第一个Intetnt，用<span style="font-family: Arial, Helvetica, sans-serif;">MediaStore.ACTION_IMAGE_CAPTURE和</span><span style="font-family: Arial, Helvetica, sans-serif;"> "Take picture"两个参数对Intent进行修饰和约束，这个Intent在</span><span style="font-family: Arial, Helvetica, sans-serif;">startActivityForResult的时候，会搜索手机里面应用的Manifest文件，找到匹配的，</span>

<span style="font-family: Arial, Helvetica, sans-serif;">如</span>

<span style="white-space:pre">	</span><intent-filter>                <action android:name="MediaStore.ACTION_IMAGE_CAPTURE" />                <category android:name="android.intent.category.LAUNCHER" />        </intent-filter>

然后这几个应用就会列在下面让我们选择了。因为要得到返回结果，别忘了覆写onActivityResult。这里只对前两个的返回结果进行处理，第三个应该也不难，对返回的data进行有没有Extra的判断应该就行了。

@Override	protected void onActivityResult(int requestCode, int resultCode, Intent data) {		System.out.println("requestCode=" + requestCode + "resultCode=" + resultCode + "data=" + data);		if (resultCode != RESULT_OK) {			super.onActivityResult(requestCode, resultCode, data);		}		else if (requestCode == PICK_PICTURE){			super.onActivityResult(requestCode, resultCode, data);			System.out.println("data1----" + data);			Uri uri = data.getData();			ContentResolver cr =this.getContentResolver();			try {				Bitmap bitmap = BitmapFactory.decodeStream(cr.openInputStream(uri));				mImageView.setImageBitmap(bitmap);			} catch (FileNotFoundException e) {				e.printStackTrace();			}		}		else if (requestCode == TAKE_PICTURE) {			super.onActivityResult(requestCode, resultCode, data);			System.out.println("data2----" + data);			Bundle bundle = data.getExtras();			if (bundle != null) {				Bitmap bitmap = (Bitmap) bundle.get("data");				mImageView.setImageBitmap(bitmap);			}		}	}

以上。