Android获取本地相册图片和拍照获取图片的实现方法

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！

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。