android 上图片选取器以及图片尺寸太大情况下处理

最新推荐文章于 2023-03-20 19:00:55 发布

原创最新推荐文章于 2023-03-20 19:00:55 发布 · 3.4k 阅读

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#android #exception #null #string #浏览器 #file

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本文探讨了在Android应用中如何选择图片，并针对图片尺寸过大导致的问题提出了解决方案，包括从资源库中选取图片的实现及大图加载优化的方法。

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代码请见我的资源http://download.youkuaiyun.com/detail/samguoyi/4351467

package test.sam.imgpickdemo;

import java.io.File;

import javax.security.auth.PrivateCredentialPermission;

import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.hardware.Camera;
import android.media.ExifInterface;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.ImageView;

public class PickPictureDemoActivity extends Activity implements View.OnClickListener
{
	private static final int ACTIVITY_PICKLOCAL = 0;
	private static final int ACTIVITY_PICKCAMERA = 1;
	
	
	private ImageView showImageView = null;
	private File imgFile = null;
	
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        findViewById(R.id.main_pickcamera).setOnClickListener(this);
        findViewById(R.id.main_picklocal).setOnClickListener(this);
        showImageView = (ImageView)findViewById(R.id.main_showimg);
    }
    
    public void onClick(View v) 
    {
    	switch (v.getId()) {
		case R.id.main_picklocal:
			/*
			 * 使用这种intent则调用任何注册过的图片浏览器，例如es文件浏览器,来选取图片
			 */
			Intent i = new Intent();
			i.setType("image/*");
			i.setAction(Intent.ACTION_GET_CONTENT);
			/*
			 * 使用这种方式只调用系统的图库程序来选取图片
			 */
			//Intent i = new Intent(Intent.ACTION_PICK,MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
			startActivityForResult(i, ACTIVITY_PICKLOCAL);
			break;
		case R.id.main_pickcamera:
			imgFile = new File(Environment.getExternalStorageDirectory(), "testpick"+System.currentTimeMillis()+".jpg");
			try {
				imgFile.createNewFile();
			} catch (Exception e) {
			}
			if(imgFile.exists())
			{
				Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
				intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(imgFile));
				startActivityForResult(intent, ACTIVITY_PICKCAMERA);
			}
			
			break;
		default:
			break;
		}
    }
    
    
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	super.onActivityResult(requestCode, resultCode, data);
    	System.out.println("resultCode = "+resultCode);
    	String photopathString = null;
    	
    	if(resultCode == RESULT_OK)
    	{
    		if(requestCode == ACTIVITY_PICKLOCAL)
        	{
        		Cursor cursor = getContentResolver().query(data.getData(), null, null, null, null);
        		cursor.moveToFirst();
        		photopathString = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
        		Bitmap bitmap = BitmapFactory.decodeFile(photopathString);
        		showImageView.setImageBitmap(bitmap);
        		cursor.close();
        		
        		/*
        		 * 这段代码可以获取图片的方向，以决定图片是横向放置还是竖向放置
        		 */
        		try {
					ExifInterface exifInterface = new ExifInterface(photopathString);
					String tag =  exifInterface.getAttribute(ExifInterface.TAG_ORIENTATION);
					System.out.println("tag = "+tag);
				} catch (Exception e) {
					e.printStackTrace();
				}
        		
        		/*
    			 * 这段代码可以将图片的长宽等信息decode出来而不需要分配内存
    			 */
        		try {
        			BitmapFactory.Options options = new BitmapFactory.Options();
        			options.inJustDecodeBounds = true;
        			BitmapFactory.decodeFile(photopathString, options);
        			System.out.println("options.outWidth = "+options.outWidth);
        			System.out.println("options.outHeight = "+options.outHeight);
				} catch (Exception e) {
				}
        		
        		/*
        		 * 使用这段代码可以缩小取得图片尺寸options.inSampleSize为几，则取得的图片大小为原来的几分之一
        		 * 注意inSampleSize需要为2的幂次方
        		 */
        		try {
        			BitmapFactory.Options options = new BitmapFactory.Options();
        			options.inSampleSize = 8;
        			Bitmap bitmap2 =  BitmapFactory.decodeFile(photopathString, options);
        			System.out.println("bitmap2.getWidth() = "+bitmap2.getWidth());
        			System.out.println("bitmap2.getHeight() = "+bitmap2.getHeight());
				} catch (Exception e) {
				}
        		
        	}
    		
    		if(requestCode == ACTIVITY_PICKCAMERA)
        	{
    			/*
    			 * 从摄像头返回的图片无法从data.getData()中取得?不知道为啥
    			 */
    			Bitmap bitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath());
    			System.out.println(bitmap.getWidth());
    			System.out.println(bitmap.getHeight());
				showImageView.setImageBitmap(bitmap);
				
        	}
    		
    	}
    	
    	
    	
    	
    }
    
}