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！

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