打造Android中万能BaseAdapter
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如题
作为一个懒人，在用了几次BaseAdapter加ViewHolder之后早已经厌倦了做同样的工作，仔细观察下我们的实现，其实有一些共处是一直有的，在BaseAdapter上再封装一次不就完事了，省了很多力气，直接上代码吧，原理其实很简单
说明：
1. 一些jar需要添加，如JSON的jar
2. MediaLoader很简单，随便写一个就行了
3. 一些后续的优化，如实现个滑动监听器，当停止滑动再加载啊，滑动就停止加载啊（注意AsyncTask的cancel()方法，不会立即停止线程的，实现原理也是线程池，也可以自己写一个玩玩，对线程的停止方法，有另一篇介绍），也可以对内容进行缓存，看自己需求吧
1。通用的ViewHolder
package util;import android.content.Context;import android.util.SparseArray;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;public class ViewHolder{ private final SparseArray<View> mViews; private int mPosition; private View mConvertView; private int myLayoutId; private ViewHolder(Context context, ViewGroup parent, int layoutId, int position) { this.mPosition = position; this.mViews = new SparseArray<View>(); this.myLayoutId = layoutId; //System.out.println("position is "+mPosition+" 初始化时的layoutID is"+myLayoutId); mConvertView = LayoutInflater.from(context).inflate(layoutId, parent, false); // setTag mConvertView.setTag(this); //System.out.println(position+"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"); } public int getMyLayoutId(){ //System.out.println("position is "+mPosition+" getLayoutId时的layoutID is"+myLayoutId); return this.myLayoutId; } public int getmPosition() { return mPosition; } public static ViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId, int position) { //System.out.println("position is "+position+" getViewHolder时传入的layoutID is"+layoutId); if (convertView == null || position != ((ViewHolder) convertView.getTag()).getmPosition()) { //System.out.println("new ViewHolder 之前 position is "+position+" getViewHolder时的layoutID is"+layoutId); return new ViewHolder(context, parent, layoutId, position); } //System.out.println("不用new的时候getViewHolder position is "+position+" getViewHolder时的layoutID is"+layoutId); return (ViewHolder) convertView.getTag(); } public View getConvertView() { return mConvertView; } public <T extends View> T getView(int viewId) { View view = mViews.get(viewId); if (view == null) { view = mConvertView.findViewById(viewId); mViews.put(viewId, view); } return (T) view; }}2.通用的Adapter
package util;import android.content.Context;import android.util.SparseArray;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.AbsListView;import android.widget.BaseAdapter;import java.util.List;/** * Created by Coder on 2017/1/1. */public abstract class CommonAdapter<T> extends BaseAdapter implements AbsListView.OnScrollListener{ protected LayoutInflater mInflater; protected Context mContext; protected List<T> beanList; protected SparseArray<Integer> mItemLayoutIds; public CommonAdapter(Context context, List<T> beanList, SparseArray<Integer> mItemLayoutIds) { this.mContext = context; this.mInflater = LayoutInflater.from(mContext); this.beanList = beanList; this.mItemLayoutIds = mItemLayoutIds; } public Context getContext(){ return mContext; } @Override public int getCount() { return beanList.size(); } @Override public T getItem(int position) { return beanList.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder = getViewHolder(position, convertView, parent); convert(viewHolder, getItem(position)); return viewHolder.getConvertView(); } public abstract void convert(ViewHolder holder, T t); private ViewHolder getViewHolder(int position, View convertView, ViewGroup parent) { //System.out.println("position is "+position+" 传入的 layoutid is"+mItemLayoutIds.get(position)); return ViewHolder.get(mContext, convertView, parent, mItemLayoutIds.get(position), position); }}3.使用示例
先搞个activity
package zzu.com.news;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.widget.ListView;import org.json.JSONArray;import org.json.JSONException;import org.json.JSONObject;import java.util.ArrayList;import java.util.List;import Adapter.NewsAdapter;import Adapter.TestAdapter;import bean.News;import util.DataHandler;import util.MyAsyncTask;public class NewsActivity extends Activity { private Context context; private ListView listVIew; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.test_adapter); context = this; listVIew = (ListView)findViewById(R.id.lv_main); new MyAsyncTask(context, listVIew).execute("http://192.168.1.107:8080/news/ShowNewsService?currentPage=5","newsList"); }}再把要显示的JSON数据从服务器获取下来,把数据和布局文件打包链表扔进NewsAdapter里，NewsAdapter是根据CommonAdapter重写的，下面有代码
package util;/** * Created by Coder on 2017/1/5. */import android.content.Context;import android.os.AsyncTask;import android.util.SparseArray;import android.widget.BaseAdapter;import android.widget.ListView;import com.google.gson.Gson;import org.json.JSONArray;import org.json.JSONException;import org.json.JSONObject;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;import java.util.ArrayList;import java.util.List;import Adapter.NewsAdapter;import Adapter.TestAdapter;import bean.ShowNewsBean;import zzu.com.news.R;/** * Created by Coder on 2017/1/5. */public class MyAsyncTask extends AsyncTask<String, Void, JSONArray> { private Context context; private ListView view; public MyAsyncTask(Context context, ListView view){ this.context = context; this.view = view; } @Override protected JSONArray doInBackground(String... params) { return DataHandler.getJsonArray(params[0], params[1]); } @Override protected void onPostExecute(JSONArray jsonArray) { super.onPostExecute(jsonArray); SparseArray<Integer> mItemLayoutIds = new SparseArray<Integer>(); List<ShowNewsBean> newsList = new ArrayList<>(); try { JSONObject jsonObject = null; for(int i=0; i<jsonArray.length(); i++){ jsonObject = jsonArray.getJSONObject(i); System.out.println(jsonObject.toString()); //对JSON-》Bean Gson gson = new Gson(); ShowNewsBean news = gson.fromJson(jsonObject.toString(), ShowNewsBean.class); System.out.println(news.toString()); newsList.add(news); //将布局传入 if(news.getNewsType() == 1){ mItemLayoutIds.put(i, R.layout.listview_demo3); }else if(news.getNewsType() == 2){ mItemLayoutIds.put(i, R.layout.listview_demo2); }else if(news.getNewsType() == 3){ mItemLayoutIds.put(i, R.layout.listview_demo); }else{ mItemLayoutIds.put(i, R.layout.video_item_layout); } } } catch (JSONException e) { e.printStackTrace(); } NewsAdapter myAdapter = new NewsAdapter(context, newsList, mItemLayoutIds); view.setAdapter(myAdapter); }}最后重写下CommonAdapter就行了
package Adapter;import android.content.Context;import android.os.Handler;import android.os.Message;import android.util.Log;import android.util.SparseArray;import android.view.View;import android.widget.AbsListView;import android.widget.Button;import android.widget.ImageButton;import android.widget.ImageView;import android.widget.MediaController;import android.widget.TextView;import android.widget.VideoView;import org.json.JSONException;import org.json.JSONObject;import java.util.ArrayList;import java.util.List;import java.util.Map;import bean.Media;import bean.ShowNewsBean;import util.CommonAdapter;import util.ImageLoader;import util.MediaLoader;import util.VideoLoader;import util.ViewHolder;import zzu.com.news.R;import com.google.gson.Gson;/** * Created by Coder on 2017/1/5. */public class NewsAdapter extends CommonAdapter<Object> { private MediaLoader mediaLoader; protected List beanList; protected List<Object> taskList; public NewsAdapter(Context context, List beanList, SparseArray<Integer> mItemLayoutIds) { super(context, beanList, mItemLayoutIds); this.beanList = beanList; taskList = new ArrayList<>(); mediaLoader = new MediaLoader(); } @Override public void convert(ViewHolder holder, Object object) { final ShowNewsBean news = (ShowNewsBean)object; //把bean中的数据塞到view中 if(news.getNewsType() == 1){ ((TextView) holder.getView(R.id.thirdtitle)).setText(news.getTitle()); System.out.println("1"); }else if(news.getNewsType() == 2){ System.out.println(" getMyLayoutId is ="+holder.getMyLayoutId()+" R.layout.listview_demo2 is "+R.layout.listview_demo2+" ~!!!!!!!!!!!!!!"); ((TextView) holder.getView(R.id.nexttitle)).setText(news.getTitle()); List<Media> mediaList = news.getMediaList(); ImageView imageView = holder.getView(R.id.nextpicture); //设置url作为tag防止重复加载 imageView.setTag(mediaList.get(0).getMediaUrl()); System.out.println("url is "+mediaList.get(0).getMediaUrl()); //imageLoader.showImageByAnsycTask(imageView, mediaList.get(0).getMediaUrl()); mediaLoader.show(imageView, mediaList.get(0).getMediaUrl()); }else if(news.getNewsType() == 3){ //设置url作为tag防止重复加载 ((TextView) holder.getView(R.id.title)).setText(news.getTitle()); List<Media> mediaList = news.getMediaList(); ImageView imageView = holder.getView(R.id.picture1); imageView.setTag(mediaList.get(0).getMediaUrl()); mediaLoader.show(imageView, mediaList.get(0).getMediaUrl()); imageView = holder.getView(R.id.picture2); imageView.setTag(mediaList.get(1).getMediaUrl()); mediaLoader.show(imageView, mediaList.get(1).getMediaUrl()); imageView = holder.getView(R.id.picture3); imageView.setTag(mediaList.get(2).getMediaUrl()); mediaLoader.show(imageView, mediaList.get(2).getMediaUrl()); }else{ ((TextView)holder.getView(R.id.video_name_text)).setText(news.getTitle()); final Context context = getContext(); final VideoView videoView = holder.getView(R.id.videoview); final ImageButton play = holder.getView(R.id.video_play_btn); play.setOnClickListener(new View.OnClickListener() { private boolean flag = false; @Override public void onClick(View v) { if(flag == false){ play.setVisibility(ImageButton.INVISIBLE); System.out.println(news.getMediaList().get(0).getMediaUrl()+"!!!!!!!!!!!!!!!"); MediaLoader mediaLoader = new MediaLoader(); mediaLoader.show(videoView, news.getMediaList().get(0).getMediaUrl()); MediaController myController = new MediaController(context); videoView.setVisibility(View.VISIBLE); myController.setAnchorView(videoView); myController.setMediaPlayer(videoView); videoView.setMediaController(myController); videoView.requestFocus(); flag = true; }else{ videoView.pause(); flag = false; } } }); } } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {// start = firstVisibleItem;// end = firstVisibleItem + visibleItemCount; Log.i("TAG", "firstVisibleItem "+firstVisibleItem); Log.i("TAG", "visibleItemCount "+visibleItemCount); Log.i("TAG", "totalItemCount "+totalItemCount); } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { if(scrollState == SCROLL_STATE_IDLE){ //停止滑动 开始加载 }else{ //正在滑动 停止加载 } }} 0 0
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