android开发(49) Android 下拉刷新的实现。使用 SwipeRefreshLayout 代替 pull-to-refesh

概述

　　谷歌官方推出了SwipeRefreshLayout 来实现下拉刷新的效果。对比以前我们常用的 pull-to-refesh ，这个方案显得更加的简单方便。

关联项目引用（管理依赖）

　　在你的 应用级别的 build.gradle  中添加如下：　　

 　　compile 'com.android.support:appcompat-v7:23.0.0'

    compile 'com.android.support:support-v4:23.0.0'

编写布局(Layout)

<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=".MainActivity">

    <android.support.v4.widget.SwipeRefreshLayout

        android:id="@+id/swipeRefreshLayout1"

        android:layout_width="match_parent"

        android:layout_height="match_parent">

        <ListView

            android:id="@+id/listview1"

            android:layout_width="match_parent"

            android:layout_height="match_parent" />

    </android.support.v4.widget.SwipeRefreshLayout>

</LinearLayout>

在代码中  添加监听器处理事件

　　public void setOnRefreshListener(OnRefreshListener listener)
　　

完整代码

package demo.vir56k.swiperefreshlayoutdemo;

import android.os.Handler;

import android.support.v4.widget.SwipeRefreshLayout;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.widget.ArrayAdapter;

import android.widget.ListView;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static final int REFRESH_COMPLETE = 0X110;

    private SwipeRefreshLayout mSwipeLayout;

    private ListView mListView;

    private ArrayAdapter<String> mAdapter;

    private List<String> mDatas;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mListView = (ListView) findViewById(R.id.listview1);

        mSwipeLayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayout1);

        mDatas = creatDataSource();

        mSwipeLayout.setOnRefreshListener(mSwipeRefreshLayoutOnRefreshListener);

        mSwipeLayout.setColorSchemeResources(android.R.color.holo_blue_bright, android.R.color.holo_green_light,

                android.R.color.holo_orange_light, android.R.color.holo_red_light);

        mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mDatas);

        mListView.setAdapter(mAdapter);

    }

    private List<String> creatDataSource() {

        mDatas = new ArrayList<String>();

        for (int i = 0; i < 5; i++) {

            mDatas.add("item" + i);

        }

        return mDatas;

    }

    SwipeRefreshLayout.OnRefreshListener mSwipeRefreshLayoutOnRefreshListener = new SwipeRefreshLayout.OnRefreshListener() {

        @Override

        public void onRefresh() {

            mHandler.sendEmptyMessageDelayed(REFRESH_COMPLETE, 2000);

        }

    };

    private Handler mHandler = new Handler() {

        public void handleMessage(android.os.Message msg) {

            switch (msg.what) {

                case REFRESH_COMPLETE:

                    List<String> lst = new ArrayList<String>();

                    for (int i = mDatas.size() + 3; i > mDatas.size(); i--) {

                        lst.add("item -" + i);

                    }

                    mDatas.addAll(0, lst);

                    mAdapter.notifyDataSetChanged();

                    mSwipeLayout.setRefreshing(false);

                    break;

            }

        }

        ;

    };

}

至此完成。

补充：

其他情形，遇到"SwipeRefreshLayout 的子控件不 直接是个listview 等，是个普通 relativewlayout 怎么办？"

解决方法： 继承 SwipeRefreshLayout 重写 canChildScrollUp 方法

/*

 * Copyright 2016, The Android Open Source Project

 *

 * 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.example.android.architecture.blueprints.todoapp.tasks;

import android.content.Context;

import android.support.v4.view.ViewCompat;

import android.support.v4.widget.SwipeRefreshLayout;

import android.util.AttributeSet;

import android.view.View;

/**

 * Extends {@link SwipeRefreshLayout} to support non-direct descendant scrolling views.

 * <p>

 * {@link SwipeRefreshLayout} works as expected when a scroll view is a direct child: it triggers

 * the refresh only when the view is on top. This class adds a way (@link #setScrollUpChild} to

 * define which view controls this behavior.

 */

public class ScrollChildSwipeRefreshLayout extends SwipeRefreshLayout {

    private View mScrollUpChild;

    public ScrollChildSwipeRefreshLayout(Context context) {

        super(context);

    }

    public ScrollChildSwipeRefreshLayout(Context context, AttributeSet attrs) {

        super(context, attrs);

    }

    @Override

    public boolean canChildScrollUp() {

        if (mScrollUpChild != null) {

            return ViewCompat.canScrollVertically(mScrollUpChild, -1);

        }

        return super.canChildScrollUp();

    }

    public void setScrollUpChild(View view) {

        mScrollUpChild = view;

    }

}