[Android] SwipeRefreshLayout實現使用者垂直滑動時進行更新

上一次我們透過Volley來取得臺北捷運列車到站資訊，此公開資料是每30秒就更新，我們要如何讓它更新呢?

在許多App上，使用者只須要到頁面的頂端，由上往下滑動，即可進行資料更新的動作，今天我們就來記錄一下，該如何做到這樣的效果。

完成圖↓

透過官方的SwipeRefreshLayout可以很輕鬆地做到這樣的功能，使用上一次的專案，將SwipeRefreshLayout加到「fragmentlist_one.xml」。

fragmentlist_one.xml

	<?xml version="1.0" encoding="utf-8"?>
	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:background="@color/white"
	android:gravity="center"
	android:orientation="horizontal">
	<ProgressBar
	android:id="@+id/progressBar"
	style="?android:attr/progressBarStyle"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_gravity="center_vertical" />
	<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:id="@+id/swipeRefreshLayout"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:visibility="gone">
	<android.support.v7.widget.RecyclerView
	android:id="@+id/recyclerView"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:clipToPadding="false" />
	</android.support.v4.widget.SwipeRefreshLayout>
	</LinearLayout>

view raw fragmentlist_one.xml hosted with ❤ by GitHub

然後，修改「FragmentList_One.java」，為SwipeRefreshLayout設置OnRefreshListener，就大功造成啦!

FragmentList_One.java

	package com.example.solinari.VerticalSwipeRefresh;
	import android.os.Bundle;
	import android.support.v4.app.Fragment;
	import android.support.v4.widget.SwipeRefreshLayout;
	import android.support.v7.widget.LinearLayoutManager;
	import android.support.v7.widget.RecyclerView;
	import android.view.LayoutInflater;
	import android.view.View;
	import android.view.ViewGroup;
	import android.widget.ProgressBar;
	import android.widget.Toast;
	import com.android.volley.Request;
	import com.android.volley.RequestQueue;
	import com.android.volley.Response;
	import com.android.volley.VolleyError;
	import com.android.volley.toolbox.JsonObjectRequest;
	import com.android.volley.toolbox.Volley;
	import org.json.JSONArray;
	import org.json.JSONException;
	import org.json.JSONObject;
	/**
	* Created by Solinari on 2016/12/31.
	*/
	public class FragmentList_One extends Fragment{
	private RecyclerView recyclerView;
	private SwipeRefreshLayout swipeRefreshLayout;
	private ProgressBar progressBar;
	private RecyclerView.Adapter recyclerAdapter;
	private String[] MetroInfo;
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
	Bundle savedInstanceState) {
	View view = inflater.inflate(R.layout.fragmentlist_one, container, false);
	recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
	progressBar = (ProgressBar) view.findViewById(R.id.progressBar);
	swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipeRefreshLayout);
	swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {//設置監聽器
	@Override
	public void onRefresh() {//當使用者於頂端垂直滑動手勢時
	getMetroInfo();//取得台北捷運列車到站資訊
	recyclerAdapter.notifyDataSetChanged();//更新RecyclerView
	swipeRefreshLayout.setRefreshing(false);//移除SwipeRefreshLayout更新時的loading圖示
	}
	});
	getMetroInfo();//取得台北捷運列車到站資訊
	return view;
	}
	public void setRecyclerView(){
	recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
	recyclerAdapter = new RecyclerViewAdapter(MetroInfo);//設置RecyclerView.Adapter
	recyclerView.setAdapter(recyclerAdapter);
	progressBar.setVisibility(View.GONE);//Loading圖隱藏
	swipeRefreshLayout.setVisibility(View.VISIBLE);//資料呈現
	}
	public void getMetroInfo(){
	RequestQueue queue = Volley.newRequestQueue(getActivity());//創建一個RequestQueue
	//台北捷運到站資料網址，按終點站排序
	String url = "http://data.taipei/opendata/datalist/apiAccess?scope=resourceAquire&rid=55ec6d6e-dc5c-4268-a725-d04cc262172b&sort=Destination";
	//對URL發出Request取得JsonObject的Response
	JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null,
	new Response.Listener<JSONObject>() {
	@Override
	public void onResponse(JSONObject response) {
	try {
	//Response的JSONObject中，我們要的資訊是results(JSONArray)
	//{"result":{"offset":0,"limit":10000,"count":25,"sort":"Destination","results":[{"_id":"1","Station":"士林站","Destination":"大安站","UpdateTime":"2017-04-10T20:59:27.577"},...}]}}
	JSONArray info = response.getJSONObject("result").getJSONArray("results");
	MetroInfo = new String[info.length()];
	for(int i = 0; i < info.length();i++){
	JSONObject jsonObject = info.getJSONObject(i);
	//{"_id":"1","Station":"士林站","Destination":"大安站","UpdateTime":"2017-04-10T20:59:27.577"}
	String time = jsonObject.getString("UpdateTime").substring(11,19);
	MetroInfo[i] = jsonObject.getString("Station") + "_" + jsonObject.getString("Destination") + "_" + time;
	}
	setRecyclerView();//設置RecyclerView
	} catch (JSONException e) {
	e.printStackTrace();
	}
	}
	}, new Response.ErrorListener() {
	@Override
	public void onErrorResponse(VolleyError error) {
	//當發生錯誤時，提示使用者發生錯誤
	MetroInfo = new String[1];
	MetroInfo[0] = "Error_Error_Error";
	setRecyclerView();
	Toast.makeText(getActivity(),"Get data error !",Toast.LENGTH_LONG).show();
	}
	}
	);
	//將Request加入RequestQueue
	queue.add(jsonObjectRequest);
	}
	}

view raw FragmentList_One.java hosted with ❤ by GitHub

參考資料：SwipeRefreshLayout
　　　　　Adding Swipe-to-Refresh To Your App
　　　　　Responding to a Refresh Request
完整專案：Solinari GitHub