万一有用的话;我这样做是为了得到位图:

InputStream is = context.getContentResolver().openInputStream(imageUri);
Bitmap bitmap = BitmapFactory.decodeStream(is);

package com.ImageConvertingDemo;

import java.io.BufferedInputStream;
import java.io.FileInputStream;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.widget.EditText;
import android.widget.ImageView;

public class MyActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        EditText tv = (EditText)findViewById(R.id.EditText01);
        ImageView iv = (ImageView)findViewById(R.id.ImageView01);
        FileInputStream in;
        BufferedInputStream buf;
            try 
            {
                in = new FileInputStream("/sdcard/smooth.png");
                buf = new BufferedInputStream(in,1070);
                System.out.println("1.................."+buf);
                byte[] bMapArray= new byte[buf.available()];
                tv.setText(bMapArray.toString());
                buf.read(bMapArray);
                Bitmap bMap = BitmapFactory.decodeByteArray(bMapArray, 0, bMapArray.length);

                /*for (int i = 0; i < bMapArray.length; i++) 
                {
                System.out.print("bytearray"+bMapArray[i]);
                }*/
                iv.setImageBitmap(bMap);
                //tv.setText(bMapArray.toString());
                //tv.setText(buf.toString());
                if (in != null) 
                {
                    in.close();
                }
                if (buf != null) 
                {
                    buf.close();
                }

            } 
            catch (Exception e) 
            {
                Log.e("Error reading file", e.toString());
            }
    }
}

这是一个完整的解决方案。我刚刚用@mad在下面的答案中提供的信息更新了这个示例代码。还可以查看下面来自@Khobaib的解决方案，解释如何处理picasa图像。

更新

我刚刚回顾了我最初的答案，并创建了一个简单的Android Studio项目，您可以从github签出并直接导入到您的系统。

https://github.com/hanscappelle/SO-2169649

(注意多个文件选择仍然需要工作)

单张图片选择

感谢用户mad，支持来自文件探索者的图像。

public class BrowsePictureActivity extends Activity {

    // this is the action code we use in our intent, 
    // this way we know we're looking at the response from our own action
    private static final int SELECT_PICTURE = 1;

    private String selectedImagePath;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        findViewById(R.id.Button01)
                .setOnClickListener(new OnClickListener() {

                    public void onClick(View arg0) {

                        // in onCreate or any event where your want the user to
                        // select a file
                        Intent intent = new Intent();
                        intent.setType("image/*");
                        intent.setAction(Intent.ACTION_GET_CONTENT);
                        startActivityForResult(Intent.createChooser(intent,
                                "Select Picture"), SELECT_PICTURE);
                    }
                });
    }

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK) {
            if (requestCode == SELECT_PICTURE) {
                Uri selectedImageUri = data.getData();
                selectedImagePath = getPath(selectedImageUri);
            }
        }
    }

    /**
     * helper to retrieve the path of an image URI
     */
    public String getPath(Uri uri) {
            // just some safety built in 
            if( uri == null ) {
                // TODO perform some logging or show user feedback
                return null;
            }
            // try to retrieve the image from the media store first
            // this will only work for images selected from gallery
            String[] projection = { MediaStore.Images.Media.DATA };
            Cursor cursor = managedQuery(uri, projection, null, null, null);
            if( cursor != null ){
                int column_index = cursor
                .getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                cursor.moveToFirst();
                String path = cursor.getString(column_index);
                cursor.close();
                return path;
            }
            // this is our fallback here
            return uri.getPath();
    }

}

选择多张图片

因为有人在评论中要求这些信息，所以最好收集信息。

在intent上设置一个额外的参数EXTRA_ALLOW_MULTIPLE:

intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);

在Result处理中检查该参数:

if (Intent.ACTION_SEND_MULTIPLE.equals(data.getAction()))
        && Intent.hasExtra(Intent.EXTRA_STREAM)) {
    // retrieve a collection of selected images
    ArrayList<Parcelable> list = intent.getParcelableArrayListExtra(Intent.EXTRA_STREAM);
    // iterate over these images
    if( list != null ) {
       for (Parcelable parcel : list) {
         Uri uri = (Uri) parcel;
         // TODO handle the images one by one here
       }
   }
} 

注意，只有API级别18+支持这一点。

检索特定类型的文件

这个示例将获得图像的副本。

static final int REQUEST_IMAGE_GET = 1;

public void selectImage() {
    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    intent.setType("image/*");
    if (intent.resolveActivity(getPackageManager()) != null) {
        startActivityForResult(intent, REQUEST_IMAGE_GET);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_IMAGE_GET && resultCode == RESULT_OK) {
        Bitmap thumbnail = data.getParcelable("data");
        Uri fullPhotoUri = data.getData();
        // Do work with photo saved at fullPhotoUri
        ...
    }
}

打开特定类型的文件

在4.4或更高版本上运行时，您请求打开由另一个应用程序管理的文件

static final int REQUEST_IMAGE_OPEN = 1;

public void selectImage() {
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
    intent.setType("image/*");
    intent.addCategory(Intent.CATEGORY_OPENABLE);
    // Only the system receives the ACTION_OPEN_DOCUMENT, so no need to test.
    startActivityForResult(intent, REQUEST_IMAGE_OPEN);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_IMAGE_OPEN && resultCode == RESULT_OK) {
        Uri fullPhotoUri = data.getData();
        // Do work with full size photo saved at fullPhotoUri
        ...
    }
}

原始来源

在上面代码的基础上，我反映了如下代码，可能它更适合:

public String getPath(Uri uri) {
    String selectedImagePath;
    //1:MEDIA GALLERY --- query from MediaStore.Images.Media.DATA
    String[] projection = { MediaStore.Images.Media.DATA };
    Cursor cursor = managedQuery(uri, projection, null, null, null);
    if(cursor != null){
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        selectedImagePath = cursor.getString(column_index);
    }else{
        selectedImagePath = null;
    }

    if(selectedImagePath == null){
        //2:OI FILE Manager --- call method: uri.getPath()
        selectedImagePath = uri.getPath();
    }
    return selectedImagePath;
}

最快的方式打开图像从画廊或相机。

原始参考:从画廊在android程序中获取图像

下面的方法将从图库或相机接收图像，并将其显示在ImageView中。所选图像将存储在内部。

XML代码

<?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:orientation="vertical"
    tools:context="com.exampledemo.parsaniahardik.uploadgalleryimage.MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btn"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="20dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Capture Image and upload to server" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Below image is fetched from server"
        android:layout_marginTop="5dp"
        android:textSize="23sp"
        android:gravity="center"
        android:textColor="#000"/>

    <ImageView
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_gravity="center"
        android:layout_marginTop="10dp"
        android:scaleType="fitXY"
        android:src="@mipmap/ic_launcher"
        android:id="@+id/iv"/>

</LinearLayout>

JAVA类

import android.content.Intent;
import android.graphics.Bitmap;
import android.media.MediaScannerConnection;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import com.androidquery.AQuery;
import org.json.JSONException;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Calendar;
import java.util.HashMap;

public class MainActivity extends AppCompatActivity implements AsyncTaskCompleteListener{

    private ParseContent parseContent;
    private Button btn;
    private ImageView imageview;
    private static final String IMAGE_DIRECTORY = "/demonuts_upload_camera";
    private final int CAMERA = 1;
    private AQuery aQuery;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        parseContent = new ParseContent(this);
        aQuery = new AQuery(this);

        btn = (Button) findViewById(R.id.btn);
        imageview = (ImageView) findViewById(R.id.iv);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                startActivityForResult(intent, CAMERA);
            }
        });

    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {

        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == this.RESULT_CANCELED) {
            return;
        }
        if (requestCode == CAMERA) {
            Bitmap thumbnail = (Bitmap) data.getExtras().get("data");
            String path = saveImage(thumbnail);
            try {
                uploadImageToServer(path);
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }

    private void uploadImageToServer(final String path) throws IOException, JSONException {

        if (!AndyUtils.isNetworkAvailable(MainActivity.this)) {
            Toast.makeText(MainActivity.this, "Internet is required!", Toast.LENGTH_SHORT).show();
            return;
        }

        HashMap<String, String> map = new HashMap<String, String>();
        map.put("url", "https://demonuts.com/Demonuts/JsonTest/Tennis/uploadfile.php");
        map.put("filename", path);
        new MultiPartRequester(this, map, CAMERA, this);
        AndyUtils.showSimpleProgressDialog(this);
    }

    @Override
    public void onTaskCompleted(String response, int serviceCode) {
        AndyUtils.removeSimpleProgressDialog();
        Log.d("res", response.toString());
        switch (serviceCode) {

            case CAMERA:
                if (parseContent.isSuccess(response)) {
                    String url = parseContent.getURL(response);
                    aQuery.id(imageview).image(url);
                }
        }
    }

    public String saveImage(Bitmap myBitmap) {
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        myBitmap.compress(Bitmap.CompressFormat.JPEG, 90, bytes);
        File wallpaperDirectory = new File(
                Environment.getExternalStorageDirectory() + IMAGE_DIRECTORY);
        // have the object build the directory structure, if needed.
        if (!wallpaperDirectory.exists()) {
            wallpaperDirectory.mkdirs();
        }

        try {
            File f = new File(wallpaperDirectory, Calendar.getInstance()
                    .getTimeInMillis() + ".jpg");
            f.createNewFile();
            FileOutputStream fo = new FileOutputStream(f);
            fo.write(bytes.toByteArray());
            MediaScannerConnection.scanFile(this,
                    new String[]{f.getPath()},
                    new String[]{"image/jpeg"}, null);
            fo.close();
            Log.d("TAG", "File Saved::--->" + f.getAbsolutePath());

            return f.getAbsolutePath();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        return "";
    }
}