listview的局部刷新

1、效果：

2、实现：使用同等级的方法修改每项的ui

public class TestAdapter extends BaseAdapter {    private SparseArray<AppFile> dataList = null;    private LayoutInflater inflater = null;    private Context mContext;    public TestAdapter(Context context, SparseArray<AppFile> dataList) {        this.inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);        this.dataList = dataList;        this.mContext = context;    }    @Override    public int getCount() {        return dataList.size();    }    @Override    public Object getItem(int position) {        return dataList.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    // 改变下载按钮的样式    private void changeBtnStyle(Button btn, boolean enable) {        if (enable) {            btn.setBackgroundResource(R.drawable.btn_download_norm);        } else {            btn.setBackgroundResource(R.drawable.btn_download_disable);        }        btn.setEnabled(enable);    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        final ViewHolder holder;        if (null == convertView) {            holder = new ViewHolder();            convertView = inflater.inflate(R.layout.listitem_app, null);            holder.layout = (LinearLayout) convertView.findViewById(R.id.gamelist_item_layout);            holder.icon = (ImageView) convertView.findViewById(R.id.app_icon);            holder.name = (TextView) convertView.findViewById(R.id.app_name);            holder.size = (TextView) convertView.findViewById(R.id.app_size);            holder.btn = (Button) convertView.findViewById(R.id.download_btn);            convertView.setTag(holder);        } else {            holder = (ViewHolder) convertView.getTag();        }        // 这里position和app.id的值是相等的        final AppFile app = dataList.get(position);        // Log.e("", "id="+app.id+", name="+app.name);        holder.name.setText(app.name);        holder.size.setText((app.downloadSize * 100.0f / app.size) + "%");        Drawable drawable = mContext.getResources().getDrawable(R.drawable.app_icon);        holder.icon.setImageDrawable(drawable);        switch (app.downloadState) {        case DownloadManager.DOWNLOAD_STATE_NORMAL:            holder.btn.setText("下载");            this.changeBtnStyle(holder.btn, true);            break;        case DownloadManager.DOWNLOAD_STATE_DOWNLOADING:            holder.btn.setText("下载中");            this.changeBtnStyle(holder.btn, false);            break;        case DownloadManager.DOWNLOAD_STATE_FINISH:            holder.btn.setText("已下载");            this.changeBtnStyle(holder.btn, false);            break;        case DownloadManager.DOWNLOAD_STATE_WAITING:            holder.btn.setText("排队中");            this.changeBtnStyle(holder.btn, false);            break;        }        holder.btn.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                DownloadFile downloadFile = new DownloadFile();                downloadFile.downloadID = app.id;                downloadFile.downloadState = DownloadManager.DOWNLOAD_STATE_WAITING;                app.downloadState = DownloadManager.DOWNLOAD_STATE_WAITING;                downloadFile.downloadSize = app.downloadSize;                downloadFile.totalSize = app.size;                holder.btn.setText("排队中");                changeBtnStyle(holder.btn, false);            }        });        return convertView;    }    static class ViewHolder {        LinearLayout layout;        ImageView icon;        TextView name;        TextView size;        Button btn;    }

3、启动多个下载线程：
////activity

listView = (ListView)this.findViewById(R.id.listview);        AppListAdapter adapter = new AppListAdapter(this, appList);        adapter.setListView(listView);        listView.setAdapter(adapter);

//adapter

public class AppListAdapter extends BaseAdapter {    private SparseArray<AppFile> dataList = null;    private LayoutInflater inflater = null;    private Context mContext;    private DownloadManager downloadManager;    private ListView listView;    public AppListAdapter(Context context, SparseArray<AppFile> dataList) {        this.inflater = (LayoutInflater) context                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);        this.dataList = dataList;        this.mContext = context;        this.downloadManager = DownloadManager.getInstance();        this.downloadManager.setHandler(mHandler);    }    public void setListView(ListView view)    {        this.listView = view;    }    @Override    public int getCount() {        return dataList.size();    }    @Override    public Object getItem(int position) {        return dataList.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    // 改变下载按钮的样式    private void changeBtnStyle(Button btn, boolean enable)    {        if(enable)        {            btn.setBackgroundResource(R.drawable.btn_download_norm);        }        else        {            btn.setBackgroundResource(R.drawable.btn_download_disable);        }        btn.setEnabled(enable);    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        final ViewHolder holder;        if (null == convertView) {            holder = new ViewHolder();            convertView = inflater.inflate(R.layout.listitem_app, null);            holder.layout = (LinearLayout) convertView                    .findViewById(R.id.gamelist_item_layout);            holder.icon = (ImageView) convertView                    .findViewById(R.id.app_icon);            holder.name = (TextView) convertView                    .findViewById(R.id.app_name);            holder.size = (TextView) convertView                    .findViewById(R.id.app_size);            holder.btn = (Button) convertView                    .findViewById(R.id.download_btn);            convertView.setTag(holder);        } else {            holder = (ViewHolder) convertView.getTag();        }        // 这里position和app.id的值是相等的        final AppFile app = dataList.get(position);        //Log.e("", "id="+app.id+", name="+app.name);        holder.name.setText(app.name);        holder.size.setText((app.downloadSize * 100.0f / app.size) + "%");        Drawable drawable = mContext.getResources().getDrawable(R.drawable.app_icon);        holder.icon.setImageDrawable(drawable);        switch(app.downloadState)        {        case DownloadManager.DOWNLOAD_STATE_NORMAL:            holder.btn.setText("下载");            this.changeBtnStyle(holder.btn, true);            break;        case DownloadManager.DOWNLOAD_STATE_DOWNLOADING:            holder.btn.setText("下载中");            this.changeBtnStyle(holder.btn, false);            break;        case DownloadManager.DOWNLOAD_STATE_FINISH:            holder.btn.setText("已下载");            this.changeBtnStyle(holder.btn, false);            break;        case DownloadManager.DOWNLOAD_STATE_WAITING:            holder.btn.setText("排队中");            this.changeBtnStyle(holder.btn, false);            break;        }        holder.btn.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                DownloadFile downloadFile = new DownloadFile();                downloadFile.downloadID = app.id;                downloadFile.downloadState = DownloadManager.DOWNLOAD_STATE_WAITING;                app.downloadState = DownloadManager.DOWNLOAD_STATE_WAITING;                downloadFile.downloadSize = app.downloadSize;                downloadFile.totalSize = app.size;                holder.btn.setText("排队中");                changeBtnStyle(holder.btn, false);                downloadManager.startDownload(downloadFile);            }        });        return convertView;    }    static class ViewHolder {        LinearLayout layout;        ImageView icon;        TextView name;        TextView size;        Button btn;    }    /**     * 使用外部类---来管理handler的异步操作     */    private Handler mHandler = new Handler() {        public void handleMessage(Message msg)        {            DownloadFile downloadFile = (DownloadFile)msg.obj;            AppFile appFile = dataList.get(downloadFile.downloadID);            appFile.downloadSize = downloadFile.downloadSize;            appFile.downloadState = downloadFile.downloadState;            // notifyDataSetChanged会执行getView函数，更新所有可视item的数据            //notifyDataSetChanged();            // 只更新指定item的数据，提高了性能            updateView(appFile.id);        }    };    // 更新指定item的数据    private void updateView(int index)    {        int visiblePos = listView.getFirstVisiblePosition();        int offset = index - visiblePos;        //Log.e("", "index="+index+"visiblePos="+visiblePos+"offset="+offset);        // 只有在可见区域才更新        if(offset < 0) return;        View view = listView.getChildAt(offset);        final AppFile app = dataList.get(index);        ViewHolder holder = (ViewHolder)view.getTag();        //Log.e("", "id="+app.id+", name="+app.name);        holder.name.setText(app.name);        holder.size.setText((app.downloadSize * 100.0f / app.size) + "%");        Drawable drawable = mContext.getResources().getDrawable(R.drawable.app_icon);        holder.icon.setImageDrawable(drawable);        switch(app.downloadState)        {        case DownloadManager.DOWNLOAD_STATE_DOWNLOADING:            holder.btn.setText("下载中");            this.changeBtnStyle(holder.btn, false);            break;        case DownloadManager.DOWNLOAD_STATE_FINISH:            holder.btn.setText("已下载");            this.changeBtnStyle(holder.btn, false);            break;        }    }}

///下载线程类：

public class DownloadManager {    // 下载状态：正常，暂停，下载中，已下载，排队中    public static final int DOWNLOAD_STATE_NORMAL = 0x00;    public static final int DOWNLOAD_STATE_PAUSE = 0x01;    public static final int DOWNLOAD_STATE_DOWNLOADING = 0x02;    public static final int DOWNLOAD_STATE_FINISH = 0x03;    public static final int DOWNLOAD_STATE_WAITING = 0x04;    // SparseArray是android中替代Hashmap的类,可以提高效率    private SparseArray<DownloadFile> downloadFiles = new SparseArray<DownloadFile>();    // 用来管理所有下载任务    private ArrayList<DownloadTask> taskList = new ArrayList<DownloadTask>();    private Handler mHandler;    private final static Object syncObj = new Object();    private static DownloadManager instance;    private ExecutorService executorService;    private DownloadManager() {        // 最多只能同时下载3个任务，其余的任务排队等待        executorService = Executors.newFixedThreadPool(3);    }    public static DownloadManager getInstance() {        if (null == instance) {            synchronized (syncObj) {                instance = new DownloadManager();            }            return instance;        }        return instance;    }    public void setHandler(Handler handler) {        this.mHandler = handler;    }    // 开始下载，创建一个下载线程    public void startDownload(DownloadFile file) {        downloadFiles.put(file.downloadID, file);        DownloadTask task = new DownloadTask(file.downloadID);        taskList.add(task);        executorService.submit(task);    }    public void stopAllDownloadTask() {        while (taskList.size() != 0) {            DownloadTask task = taskList.remove(0);            // 可以在这里做其他的处理            task.stopTask();        }        // 会停止正在进行的任务和拒绝接受新的任务        executorService.shutdownNow();    }    // 下载任务    class DownloadTask implements Runnable {        private boolean isWorking = false;        private int downloadId;        public DownloadTask(int id) {            this.isWorking = true;            this.downloadId = id;        }        public void stopTask() {            this.isWorking = false;        }        // 更新listview中对应的item        public void update(DownloadFile downloadFile) {            Message msg = mHandler.obtainMessage();            if (downloadFile.totalSize == downloadFile.downloadSize)                downloadFile.downloadState = DOWNLOAD_STATE_FINISH;            msg.obj = downloadFile;            msg.sendToTarget();        }        public void run() {            // 更新下载文件的状态            DownloadFile downloadFile = downloadFiles.get(downloadId);            downloadFile.downloadState = DOWNLOAD_STATE_DOWNLOADING;            while (isWorking) {                // 检测是否下载完成                if (downloadFile.downloadState != DOWNLOAD_STATE_DOWNLOADING) {                    downloadFiles.remove(downloadFile.downloadID);                    taskList.remove(this);                    isWorking = false;                    break;                }                // Log.e("", "downloadSize="+downloadFile.downloadSize+"; size="+downloadFile.totalSize);                // 这里只是模拟了下载，每一秒更新一次item的下载状态                if (downloadFile.downloadSize <= downloadFile.totalSize) {                    this.update(downloadFile);                }                if (downloadFile.downloadSize < downloadFile.totalSize) {                    try {                        Thread.sleep(100);                    } catch (InterruptedException e) {                        e.printStackTrace();                        downloadFile.downloadState = DOWNLOAD_STATE_PAUSE;                        this.update(downloadFile);                        downloadFiles.remove(downloadId);                        isWorking = false;                        break;                    }                    ++downloadFile.downloadSize;                }            }        }    }}