gridview上拉下拉源码

/*******************************************************************************
 * Copyright 2011, 2012 Chris Banes.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.handmark.pulltorefresh.samples;

import java.util.Arrays;
import java.util.LinkedList;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.TextView;
import android.widget.Toast;

import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener2;
import com.handmark.pulltorefresh.library.PullToRefreshGridView;

public final class PullToRefreshGridActivity extends Activity {

    static final int MENU_SET_MODE = 0;

    private LinkedList<String> mListItems;
    private PullToRefreshGridView mPullRefreshGridView;
    private GridView mGridView;
    private ArrayAdapter<String> mAdapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ptr_grid);

        mPullRefreshGridView = (PullToRefreshGridView) findViewById(R.id.pull_refresh_grid);
        mGridView = mPullRefreshGridView.getRefreshableView();

        // Set a listener to be invoked when the list should be refreshed.
        mPullRefreshGridView.setOnRefreshListener(new OnRefreshListener2<GridView>() {

            @Override
            public void onPullDownToRefresh(PullToRefreshBase<GridView> refreshView) {
                Toast.makeText(PullToRefreshGridActivity.this, "Pull Down!", Toast.LENGTH_SHORT).show();
                new GetDataTask().execute();
            }

            @Override
            public void onPullUpToRefresh(PullToRefreshBase<GridView> refreshView) {
                Toast.makeText(PullToRefreshGridActivity.this, "Pull Up!", Toast.LENGTH_SHORT).show();
                new GetDataTask().execute();
            }

        });

        mListItems = new LinkedList<String>();

        TextView tv = new TextView(this);
        tv.setGravity(Gravity.CENTER);
        tv.setText("Empty View, Pull Down/Up to Add Items");
        mPullRefreshGridView.setEmptyView(tv);

        mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mListItems);
        mGridView.setAdapter(mAdapter);
    }

    private class GetDataTask extends AsyncTask<Void, Void, String[]> {

        @Override
        protected String[] doInBackground(Void... params) {
            // Simulates a background job.
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
            }
            return mStrings;
        }

        @Override
        protected void onPostExecute(String[] result) {
            mListItems.addFirst("Added after refresh...");
            mListItems.addAll(Arrays.asList(result));
            mAdapter.notifyDataSetChanged();

            // Call onRefreshComplete when the list has been refreshed.
            mPullRefreshGridView.onRefreshComplete();

            super.onPostExecute(result);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add(0, MENU_SET_MODE, 0,
                mPullRefreshGridView.getMode() == Mode.BOTH ? "Change to MODE_PULL_DOWN"
                        : "Change to MODE_PULL_BOTH");
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        MenuItem setModeItem = menu.findItem(MENU_SET_MODE);
        setModeItem.setTitle(mPullRefreshGridView.getMode() == Mode.BOTH ? "Change to MODE_PULL_FROM_START"
                : "Change to MODE_PULL_BOTH");

        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case MENU_SET_MODE:
                mPullRefreshGridView
                        .setMode(mPullRefreshGridView.getMode() == Mode.BOTH ? Mode.PULL_FROM_START
                                : Mode.BOTH);
                break;
        }

        return super.onOptionsItemSelected(item);
    }

    private String[] mStrings = { "Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi",
            "Acorn", "Adelost", "Affidelice au Chablis", "Afuega‘l Pitu", "Airag", "Airedale", "Aisy Cendre",
            "Allgauer Emmentaler" };
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

<!-- The PullToRefreshGridView replaces a standard GridView widget. -->
    <com.handmark.pulltorefresh.library.PullToRefreshGridView
        xmlns:ptr="http://schemas.android.com/apk/res-auto"
        android:id="@+id/pull_refresh_grid"
        android:layout_height="fill_parent"
        android:layout_width="fill_parent"
        android:numColumns="auto_fit"
        android:verticalSpacing="1dp"
        android:horizontalSpacing="1dp"
        android:columnWidth="100dp"
        android:stretchMode="columnWidth"
        android:gravity="fill"
        ptr:ptrMode="both"
        ptr:ptrDrawable="@drawable/android" />

</LinearLayout>