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。