Android获取本地相册图片、拍照获取图片，

Android获取本地相册图片、拍照获取图片，

需求：从本地相册找图片，或通过调用系统相机拍照得到图片。

容易出错的地方：

1，当我们指定了照片的uri路径，我们就不能通过data.getData();来获取uri，而应该直接拿到uri(用全局变量或者其他方式)然后设置给imageView

imageView.setImageURI(uri);

2，我发现手机前置摄像头拍出来的照片只有几百KB，直接用imageView.setImageURI(uri);没有很大问题，但是后置摄像头拍出来的照片比较大，这个时候使用imageView.setImageURI(uri);就容易出现 out of memory（oom）错误，我们需要先把URI转换为Bitmap,再压缩bitmap，然后通过imageView.setImageBitmap(bitmap);来显示图片。

3，将照片存放到SD卡中后，照片不能立即出现在系统相册中，因此我们需要发送广播去提醒相册更新照片。

4，这里用到了sharepreference，要注意用完之后移除缓存。

代码：

MainActivity:

package com.sctu.edu.test;

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.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;

import com.sctu.edu.test.tools.ImageTools;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    private static final int PHOTO_FROM_GALLERY = 1;
    private static final int PHOTO_FROM_CAMERA = 2;
    private ImageView imageView;
    private File appDir;
    private Uri uriForCamera;
    private Date date;
    private String str = "";
    private SharePreference sharePreference;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Android不推荐使用全局变量，我在这里使用了sharePreference
        sharePreference = SharePreference.getInstance(this);
        imageView = (ImageView) findViewById(R.id.imageView);
    }

    //从相册取图片
    public void gallery(View view) {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(intent, PHOTO_FROM_GALLERY);
    }

    //拍照取图片
    public void camera(View view) {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

        uriForCamera = Uri.fromFile(createImageStoragePath());
        sharePreference.setCache("uri", String.valueOf(uriForCamera));
        
        /**
         *  指定了uri路径，startActivityForResult不返回intent，
         *  所以在onActivityResult()中不能通过data.getData()获取到uri;
         */
        intent.putExtra(MediaStore.EXTRA_OUTPUT, uriForCamera);
        startActivityForResult(intent, PHOTO_FROM_CAMERA);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        //第一层switch
        switch (requestCode) {
            case PHOTO_FROM_GALLERY:
                //第二层switch
                switch (resultCode) {
                    case RESULT_OK:
                        if (data != null) {
                            Uri uri = data.getData();
                            imageView.setImageURI(uri);
                        }
                        break;
                    case RESULT_CANCELED:
                        break;
                }
                break;
            case PHOTO_FROM_CAMERA:
                if (resultCode == RESULT_OK) {
                    Uri uri = Uri.parse(sharePreference.getString("uri"));
                    updateDCIM(uri);
                    try {
                        //把URI转换为Bitmap，并将bitmap压缩，防止OOM(out of memory)
                        Bitmap bitmap = ImageTools.getBitmapFromUri(uri, this);
                        imageView.setImageBitmap(bitmap);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                    removeCache("uri");
                } else {
                    Log.e("result", "is not ok" + resultCode);
                }
                break;
            default:
                break;
        }
    }

    /**
     * 设置相片存放路径，先将照片存放到SD卡中，再操作
     *
     * @return
     */
    private File createImageStoragePath() {
        if (hasSdcard()) {
            appDir = new File("/sdcard/testImage/");
            if (!appDir.exists()) {
                appDir.mkdirs();
            }
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
            date = new Date();
            str = simpleDateFormat.format(date);
            String fileName = str + ".jpg";
            File file = new File(appDir, fileName);
            return file;
        } else {
            Log.e("sd", "is not load");
            return null;
        }
    }
    
    /**
     * 将照片插入系统相册，提醒相册更新
     *
     * @param uri
     */
    private void updateDCIM(Uri uri) {
        Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        intent.setData(uri);
        this.sendBroadcast(intent);

        Bitmap bitmap = BitmapFactory.decodeFile(uri.getPath());
        MediaStore.Images.Media.insertImage(getContentResolver(), bitmap, "", "");
    }

    /**
     * 判断SD卡是否可用
     *
     * @return
     */
    private boolean hasSdcard() {
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * 移除缓存
     *
     * @param cache
     */
    private void removeCache(String cache) {
        if (sharePreference.ifHaveShare(cache)) {
            sharePreference.removeOneCache(cache);
        } else {
            Log.e("this cache", "is not exist.");
        }
    }

}


ImageTools:

package com.sctu.edu.test.tools;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public class ImageTools {

    /**
     * 通过uri获取图片并进行压缩
     *
     * @param uri
     * @param activity
     * @return
     * @throws IOException
     */
    public static Bitmap getBitmapFromUri(Uri uri, Activity activity) throws IOException {
        InputStream inputStream = activity.getContentResolver().openInputStream(uri);
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        options.inDither = true;
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        BitmapFactory.decodeStream(inputStream, null, options);
        inputStream.close();

        int originalWidth = options.outWidth;
        int originalHeight = options.outHeight;
        if (originalWidth == -1 || originalHeight == -1) {
            return null;
        }

        float height = 800f;
        float width = 480