从相机or相册获取图片并显示

package com.example.photo;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;



import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

	Button camera, gallery;
	ImageView photo;
	private static int CAMERA_REQUEST_CODE = 1;
	private static int GALLERY_REQUEST_CODE = 2;
	private static int SCALE=5;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		camera=(Button)findViewById(R.id.camera);
		gallery=(Button)findViewById(R.id.gallery);
		photo=(ImageView)findViewById(R.id.photo);
		camera.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				Intent openCameraIntent = new Intent(
						MediaStore.ACTION_IMAGE_CAPTURE);
				
				//这里如果不加入访问SD卡权限会报错
				// <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" >
				// <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
				
				Uri imageUri = Uri.fromFile(new File(Environment
						.getExternalStorageDirectory(), "test.png"));
				// 指定照片保存路径（SD卡），test.png为一个临时文件，每次拍照后这个图片都会被替换
				openCameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
				startActivityForResult(openCameraIntent, CAMERA_REQUEST_CODE);
			}
		});

		gallery.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
				intent.setType("image/*");
				Uri imageUri = Uri.fromFile(new File(Environment
						.getExternalStorageDirectory(), "test.png"));
				// 指定照片保存路径（SD卡），test.png为一个临时文件，每次拍照后这个图片都会被替换
				intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
				startActivityForResult(intent, GALLERY_REQUEST_CODE);

			}
		});
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		//另外，使用保存文件之后再读取而不是直接用data的原因是，这里返回的data是一个缩略图，十分不清晰
		
		if (requestCode == CAMERA_REQUEST_CODE) {// 将保存在本地的图片取出并缩小后显示在界面上
			Bitmap bitmap = BitmapFactory.decodeFile(Environment
					.getExternalStorageDirectory()
					+ "/test.png");
			Bitmap newBitmap = ImageTools.zoomBitmap(bitmap, bitmap.getWidth()
					/ SCALE, bitmap.getHeight() / SCALE);
			// 由于Bitmap内存占用较大，这里需要回收内存，否则会报out of memory异常
			bitmap.recycle();
			// 将处理过的图片显示在界面上，并保存到本地
			ImageView imageView = (ImageView) findViewById(R.id.photo);
			imageView.setImageBitmap(newBitmap);

		} else if (requestCode == GALLERY_REQUEST_CODE) {
			if (data == null)
				return;
			else {
				Uri uri;
				uri = data.getData();
				try {
					Bitmap bm = MediaStore.Images.Media.getBitmap(
							this.getContentResolver(), uri);
					ImageView imageView = (ImageView) findViewById(R.id.photo);
					imageView.setImageBitmap(bm);
				} catch (FileNotFoundException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}

}