Android从系统Gallery获取图片具体实现

<activity android:name="com.android.camera.ImageGallery"
                android:label="@string/gallery_label"
                android:configChanges="orientation|keyboardHidden"
                android:icon="@drawable/ic_launcher_gallery">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="vnd.android.cursor.dir/image" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="vnd.android.cursor.dir/video" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.GET_CONTENT" />
                <category android:name="android.intent.category.OPENABLE" />
                <data android:mimeType="vnd.android.cursor.dir/image" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.GET_CONTENT" />
                <category android:name="android.intent.category.OPENABLE" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="image/*" />
                <data android:mimeType="video/*" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.PICK" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="image/*" />
                <data android:mimeType="video/*" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.PICK" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="vnd.android.cursor.dir/image" />
            </intent-filter>
        </activity>

private void launchCropperOrFinish(IImage img) {
        Bundle myExtras = getIntent().getExtras();

        long size = MenuHelper.getImageFileSize(img);
        if (size < 0) {
            // Return if the image file is not available.
            return;
        }

        if (size > mVideoSizeLimit) {
            DialogInterface.OnClickListener buttonListener =
                    new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            };
            new AlertDialog.Builder(this)
                    .setIcon(android.R.drawable.ic_dialog_info)
                    .setTitle(R.string.file_info_title)
                    .setMessage(R.string.video_exceed_mms_limit)
                    .setNeutralButton(R.string.details_ok, buttonListener)
                    .show();
            return;
        }

        String cropValue = myExtras != null ? myExtras.getString("crop") : null;
        if (cropValue != null) {
            Bundle newExtras = new Bundle();
            if (cropValue.equals("circle")) {
                newExtras.putString("circleCrop", "true");
            }

            Intent cropIntent = new Intent();
            cropIntent.setData(img.fullSizeImageUri());
            cropIntent.setClass(this, CropImage.class);
            cropIntent.putExtras(newExtras);

            /* pass through any extras that were passed in */
            cropIntent.putExtras(myExtras);
            startActivityForResult(cropIntent, CROP_MSG);
        } else {
            Intent result = new Intent(null, img.fullSizeImageUri());
            if (myExtras != null && myExtras.getBoolean("return-data")) {
                // The size of a transaction should be below 100K.
                Bitmap bitmap = img.fullSizeBitmap(
                        IImage.UNCONSTRAINED, 100 * 1024);
                if (bitmap != null) {
                    result.putExtra("data", bitmap);
                }
            }
            setResult(RESULT_OK, result);
            finish();
        }
    }

package cn.bgxt.sysgallerydemo;

import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.app.Activity;
import android.content.Intent;

public class MainActivity extends Activity {
    private Button btn_getImage;
    private ImageView iv_image;
    private final static String TAG = "main";

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

        btn_getImage = (Button) findViewById(R.id.btn_getImage);
        iv_image = (ImageView) findViewById(R.id.iv_image);

        btn_getImage.setOnClickListener(getImage);
    }

    private View.OnClickListener getImage = new OnClickListener() {

        @Override
        public void onClick(View v) {
            // 设定action和miniType
            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_PICK);
            intent.setType("image/*");
            // 以需要返回值的模式开启一个Activity
            startActivityForResult(intent, 0);
        }
    };

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // 如果获取成功，resultCode为-1
        Log.i(TAG, "resultCode:" + resultCode);
        if (requestCode == 0 && resultCode == -1) {
            // 获取原图的Uri，它是一个内容提供者
            Uri uri = data.getData();
            iv_image.setImageURI(uri);
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}