分享实现Android图片选择的两种方式

android选择图片的两种方式：

第一种：单张选取

通过隐式启动activity，跳转到相册选择一张返回结果

关键代码如下：

发送请求：

private static final int picture = 10086; //requestcode

intent intent = new intent();
if (build.version.sdk_int < 19) {//因为android sdk在4.4版本后图片action变化了 所以在这里先判断一下
      intent.setaction(intent.action_get_content);
    } else {
      intent.setaction(intent.action_open_document);
    }
    intent.settype("image/*");
    intent.addcategory(intent.category_openable);
startactivityforresult(intent, picture);

接收结果：

@override
  protected void onactivityresult(int requestcode, int resultcode, intent data) {
    if (data == null) {
      this.finish();
      return;
    }
    uri uri = data.getdata();
    switch (requestcode) {
      case picture:
        image = fileutils.geturipath(this, uri); //（因为4.4以后图片uri发生了变化）通过文件工具类 对uri进行解析得到图片路径
        break;
      default:
        break;
    }
    this.finish();
  }

文件工具类：

public class fileutils {
  private static final string tag = "fileutils";
  private static final boolean debug = false;
  /**
   * 获取可读的文件大小
   */
  public static string getreadablefilesize(int size) {
    final int bytes_in_kilobytes = 1024;
    final decimalformat dec = new decimalformat("###.#");
    final string kilobytes = " kb";
    final string megabytes = " mb";
    final string gigabytes = " gb";
    float filesize = 0;
    string suffix = kilobytes;
    if(size > bytes_in_kilobytes) {
      filesize = size / bytes_in_kilobytes;
      if(filesize > bytes_in_kilobytes) {
        filesize = filesize / bytes_in_kilobytes;
        if(filesize > bytes_in_kilobytes) {
          filesize = filesize / bytes_in_kilobytes;
          suffix = gigabytes;
        } else {
          suffix = megabytes;
        }
      }
    }
    return string.valueof(dec.format(filesize) + suffix);
  }
  /**
   * 获取文件的文件名(不包括扩展名)
   */
  public static string getfilenamewithoutextension(string path) {
    if(path == null) {
      return null;
    }
    int separatorindex = path.lastindexof(file.separator);
    if(separatorindex < 0) {
      separatorindex = 0;
    }
    int dotindex = path.lastindexof(".");
    if(dotindex < 0) {
      dotindex = path.length();
    } else if(dotindex < separatorindex) {
      dotindex = path.length();
    }
    return path.substring(separatorindex + 1, dotindex);
  }
  /**
   * 获取文件名
   */
  public static string getfilename(string path) {
    if(path == null) {
      return null;
    }
    int separatorindex = path.lastindexof(file.separator);
    return (separatorindex < 0) ? path : path.substring(separatorindex + 1, path.length());
  }
  /**
   * 获取扩展名
   */
  public static string getextension(string path) {
    if(path == null) {
      return null;
    }
    int dot = path.lastindexof(".");
    if(dot >= 0) {
      return path.substring(dot);
    } else {
      return "";
    }
  }
  public static file geturifile(context context, uri uri) {
    string path = geturipath(context, uri);
    if(path == null) {
      return null;
    }
    return new file(path);
  }
  public static string geturipath(context context, uri uri) {
    if(uri == null) {
      return null;
    }
    if(build.version.sdk_int >= build.version_codes.kitkat && documentscontract.isdocumenturi(context, uri)) {
      if("com.android.externalstorage.documents".equals(uri.getauthority())) {
        final string docid = documentscontract.getdocumentid(uri);
        final string[] split = docid.split(":");
        final string type = split[0];
        if("primary".equalsignorecase(type)) {
          return environment.getexternalstoragedirectory() + "/" + split[1];
        }
      } else if("com.android.providers.downloads.documents".equals(uri.getauthority())) {
        final string id = documentscontract.getdocumentid(uri);
        final uri contenturi = contenturis.withappendedid(uri.parse("content://downloads/public_downloads"), long.valueof(id));
        return getdatacolumn(context, contenturi, null, null);
      } else if("com.android.providers.media.documents".equals(uri.getauthority())) {
        final string docid = documentscontract.getdocumentid(uri);
        final string[] split = docid.split(":");
        final string type = split[0];
        uri contenturi = null;
        if("image".equals(type)) {
          contenturi = mediastore.images.media.external_content_uri;
        } else if("video".equals(type)) {
          contenturi = mediastore.video.media.external_content_uri;
        } else if("audio".equals(type)) {
          contenturi = mediastore.audio.media.external_content_uri;
        }
        final string selection = "_id=?";
        final string[] selectionargs = new string[] {split[1]};
        return getdatacolumn(context, contenturi, selection, selectionargs);
      }
    } else if("content".equalsignorecase(uri.getscheme())) {
      if("com.google.android.apps.photos.content".equals(uri.getauthority())) {
        return uri.getlastpathsegment();
      }
      return getdatacolumn(context, uri, null, null);
    } else if("file".equalsignorecase(uri.getscheme())) {
      return uri.getpath();
    }
    return null;
  }
  public static string getdatacolumn(context context, uri uri, string selection, string[] selectionargs) {
    cursor cursor = null;
    final string column = "_data";
    final string[] projection = {column};
    try {
      cursor = context.getcontentresolver().query(uri, projection, selection, selectionargs, null);
      if(cursor != null && cursor.movetofirst()) {
        final int column_index = cursor.getcolumnindexorthrow(column);
        return cursor.getstring(column_index);
      }
    } finally {
      if(cursor != null) cursor.close();
    }
    return null;
  }
}

第二种方式 批量选择图片

如果我们需要类似于微信那样的一次选取多张图片，很明显第一种方式是不能满足需求，那么怎么才能批量选取呢？andorid并提供像单张选取似的批量选取的直接方法，所以我们只能自己从数据库中获得。

首先我们要认识一个类mediastore  android中所有的多媒体文件都存储在这个数据库中，例如图片 视频 音频 等等，他通过contentprovider 向其他进程提供数据的接口

想要从mediastore中获得数据，我们可以使用与contentprovider 对应的contentresolver

关键代码：

 final string[] projectionphotos = {
        mediastore.images.media._id,//每一列的id 图片的id
        mediastore.images.media.bucket_id,//图片所在文件夹id
        mediastore.images.media.bucket_display_name,//图片所在文件夹名称
        mediastore.images.media.data,//图片路径
        mediastore.images.media.date_taken,//图片创建时间
    };

 
cursor = mediastore.images.media.query(context.getcontentresolver(), mediastore.images.media.external_content_uri
    , projectionphotos, "", null, mediastore.images.media.date_taken + " desc");

所有图片都在cursor里了 再从cursor中取出即可