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 = 480f;
        int be = 1;  //be=1表示不缩放
        if (originalWidth > originalHeight && originalWidth > width) {
            be = (int) (originalWidth / width);
        } else if (originalWidth < originalHeight && originalHeight > height) {
            be = (int) (originalHeight / height);
        }

        if (be <= 0) {
            be = 1;
        }
        BitmapFactory.Options bitmapOptinos = new BitmapFactory.Options();
        bitmapOptinos.inSampleSize = be;
        bitmapOptinos.inDither = true;
        bitmapOptinos.inPreferredConfig = Bitmap.Config.ARGB_8888;
        inputStream = activity.getContentResolver().openInputStream(uri);

        Bitmap bitmap = BitmapFactory.decodeStream(inputStream, null, bitmapOptinos);
        inputStream.close();

        return compressImage(bitmap);
    }

    /**
     * 质量压缩方法
     *
     * @param bitmap
     * @return
     */
    public static Bitmap compressImage(Bitmap bitmap) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, byteArrayOutputStream);
        int options = 100;
        while (byteArrayOutputStream.toByteArray().length / 1024 > 100) {
            byteArrayOutputStream.reset();
            //第一个参数 ：图片格式 ，第二个参数： 图片质量，100为最高，0为最差  ，第三个参数：保存压缩后的数据的流
            bitmap.compress(Bitmap.CompressFormat.JPEG, options, byteArrayOutputStream);
            options -= 10;
        }
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        Bitmap bitmapImage = BitmapFactory.decodeStream(byteArrayInputStream, null, null);
        return bitmapImage;
    }
}

AndroidMainfest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest package="com.sctu.edu.test"
          xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-feature
        android:name="android.hardware.camera"
        android:required="true"
        />

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="com.miui.whetstone.permission.ACCESS_PROVIDER"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-feature android:name="android.hardware.camera.autofocus" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<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:background="#fff"
    android:orientation="vertical"
    tools:context="com.sctu.edu.test.MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="从图库找图片"
        android:id="@+id/gallery"
        android:onClick="gallery"
        android:background="#ccc"
        android:textSize="20sp"
        android:padding="10dp"
        android:layout_marginLeft="30dp"
        android:layout_marginTop="40dp"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="拍照获取图片"
        android:id="@+id/camera"
        android:onClick="camera"
        android:background="#ccc"
        android:textSize="20sp"
        android:padding="10dp"
        android:layout_marginLeft="30dp"
        android:layout_marginTop="40dp"
        />

    <ImageView
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:id="@+id/imageView"
        android:scaleType="fitXY"
        android:background="@mipmap/ic_launcher"
        android:layout_marginTop="40dp"
        android:layout_marginLeft="30dp"
        />

</LinearLayout>

效果图：

        

或许有人会问，在Android6.0上面怎么点击拍照就出现闪退，那是因为我设置的最高SDK版本大于23，而我现在还没对运行时权限做处理，也许我会在下一篇博客里处理这个问题。谢谢浏览，希望对你有帮助！