Question

我有一个导航抽屉，里面有很多选项

图片资料
视频素材
音频素材

我们正在为每种材料维护单独的片段，每个片段都有网格视图，我们在其中填充该材质的缩略图。用户点击缩略图后，将下载完整的材料（使用AsyncTask）。我在下载完整材料时在缩略图上显示进度条。

现在我在这里遇到一个问题，假设进度条显示20％并且我将片段切换到另一个并再次返回到同一个并且下载进度条丢失。

我找到了使用意向服务和广播接收器来填充进度条的解决方案，但在这种情况下，在每个添加的字节上进行广播都是一种很好的做法吗？

Answer 1

作为一个抽象蓝图，您可以向您的应用添加下载Service，然后让它下载您的资料。

为了与此服务进行通信，您可能希望将其声明为bind-able服务，以便每当用户切换到该片段时，您的活动都可以绑定到此服务并查看正在进行的操作。

使用这种方式，您可以向用户报告下载进度，并且您不再需要发送广播。

Answer 2

之前的答案不够好，我做了一个新的，看一看，效果很好。

代码由片段的基类，两个片段，用于保存网格元素和主UI线程的数据的模型组成。

基类：

QuandlConnection conn = new QuandlConnection ();
string json = conn.Request(request); // request is your QuandlDownloadRequst
RootObject obj = JsonConvert.DeserializeObject<RootObject>(json);

fr1.java：

import android.app.Activity;
import android.app.Fragment;
import android.content.Context;
import android.graphics.Color;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by Movsar Bekaev on 20/09/2015.
 */
public class GridFragment extends Fragment {
    static ArrayList<xThumbnail> myInformation;
    static Activity mActivity;
    GAdapter adapter;
    GridView grid;

    enum fragment_names {FR1, FR2}

    static fragment_names this_fragment_name;

    public GridFragment() {
        refresh();
    }

    protected void refresh() {
        if (grid == null) {
            grid = new GridView(mActivity);
            grid.setLayoutParams(new GridView.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT));
            grid.setBackgroundColor(Color.WHITE);
            grid.setNumColumns(2);
            grid.setColumnWidth(GridView.AUTO_FIT);
            grid.setVerticalSpacing(5);
            grid.setHorizontalSpacing(5);
            grid.setStretchMode(GridView.STRETCH_COLUMN_WIDTH);
        }
        adapter = new GAdapter(mActivity, myInformation);
        grid.setAdapter(adapter);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        refresh();
        return grid;
    }


    public class GAdapter extends BaseAdapter {
        private Context mContext;
        private ArrayList<xThumbnail> mInfo;

        // Gets the context so it can be used later
        public GAdapter(Context c, ArrayList<xThumbnail> info) {
            mInfo = info;
            mContext = c;

        }

        // Total number of things contained within the adapter
        public int getCount() {
            return mInfo.size();
        }

        public xThumbnail getItem(int position) {
            return mInfo.get(position);
        }

        // Require for structure, not really used in my code. Can
        // be used to get the id of an item in the adapter for
        // manual control.
        public long getItemId(int position) {
            return position;
        }

        public View getView(final int position,
                            View convertView, ViewGroup parent) {

            View v;
            if (convertView == null) {
                LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                v = inflater.inflate(R.layout.thumbnail, null);
                final TextView tv = (TextView) v.findViewById(R.id.tvClickMe);
                final ProgressBar pb = (ProgressBar) v.findViewById(R.id.prgb_progress);
                pb.setProgress(mInfo.get(position).getProgress());
                tv.setText(mInfo.get(position).getProgress() + "");
                mInfo.get(position).setProgressBar(pb);
                mInfo.get(position).setTextView(tv);
                tv.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        runOp(mInfo.get(position), position, this_fragment_name);
                    }
                });
            } else {
                v = convertView;
            }
            return v;
        }
    }

    private void runOp(final xThumbnail x, final int position, final fragment_names f_name) {
        if (x.xt == null) {
            x.xt = new Thread(new Runnable() {
                @Override
                public void run() {
                    for (int i = x.getProgress(); i <= 100; i++) {

                        //  UNCOMMENT IF YOU WANT TO STOP THE PROCESS AFTER SWITCHING
                        //   if ((f_name == this_fragment_name) && !mThread.isInterrupted()) {
                        final int progress = i;
                        mActivity.runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                x.setProgressBar(adapter.getItem(position).getProgressBar());
                                x.setTextView(adapter.getItem(position).getTextView());
                                x.setProgress(progress);
                                x.getProgressBar().setProgress(progress);
                                x.getTextView().setText(progress + "");
                                // ARBITRARY CHANGE OF MYINFORMATION
                                // JUST TO SHOW THAT IT WORKS
                                if (progress == 20) {
                                    myInformation.get(3).setProgress(12);
                                    refresh();
                                }
                                // **********************************
                            }
                        });
                        try {
                            Thread.sleep(150);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        //  } else {
                        //       return;
                        //  }
                    }
                }
            });
        }
        if (!x.xt.isAlive())
            x.xt.start();
    }
}

fr2.java：

 public class fr1 extends GridFragment {
    static ArrayList<xThumbnail> fr1Info;

    public static fr1 newInstance(Activity act) {
        mActivity = act;
        return new fr1();
    }

    @Override
    protected void refresh() {
        if (fr1Info == null || fr1Info.size() == 0) {
            fr1Info = new ArrayList<>();
            for (int i = 0; i < 10; i++) {
                xThumbnail x;
                x = new xThumbnail();
                fr1Info.add(x);
            }

        }
        myInformation = fr1Info;
        super.refresh();
    }
}

xThumbnail.java（型号）：

  public class fr2 extends GridFragment {
    static ArrayList<xThumbnail> fr2Info;

    public static fr2 newInstance(Activity act) {
        mActivity = act;
        return new fr2();
    }

    @Override
    protected void refresh() {
        if (fr2Info == null || fr2Info.size() == 0) {
            fr2Info = new ArrayList<>();
            for (int i = 0; i < 10; i++) {
                xThumbnail x;
                x = new xThumbnail();
                fr2Info.add(x);
            }
        }
        myInformation = fr2Info;
        super.refresh();
    }
}

MainActivity.java：

    public class xThumbnail {    
    private int prgb_value = 0;
    private ProgressBar pb;
    private TextView tv;
    public Thread xt;

    public void setProgress(Integer i) {
        prgb_value = i;
    }

    public Integer getProgress() {
        return prgb_value;
    }

    public void setProgressBar(ProgressBar prb) {
        pb = prb;
    }

    public ProgressBar getProgressBar() {
        return pb;
    }

    public void setTextView(TextView tv) {
        this.tv = tv;
    }

    public TextView getTextView() {
        return tv;
    }
}

<强> activity_main.xml中：

 public class MainActivity extends AppCompatActivity {
        Button btn_one, btn_two;
        fr1 mFr1;
        fr2 mFr2;
        FragmentManager fm = getFragmentManager();

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            btn_one = (Button) findViewById(R.id.btn_one);
            btn_two = (Button) findViewById(R.id.btn_two);

            mFr1 = (fr1) fm.findFragmentByTag("fr1");
            mFr2 = (fr2) fm.findFragmentByTag("fr2");
           final FrameLayout frameLayout = (FrameLayout)findViewById(R.id.frLayout);

            btn_one.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

               GridFragment.this_fragment_name= GridFragment.fragment_names.FR1;

                if (mFr1 == null) {
                    mFr1 = fr1.newInstance(MainActivity.this);
                    fm.beginTransaction().add(R.id.frLayout, mFr1, "fr1").commit();
                } else {
                    fm.beginTransaction().detach(mFr1).commit();
                    fm.beginTransaction().attach(mFr1).commit();

                }
            }
        });

        btn_two.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                GridFragment.this_fragment_name= GridFragment.fragment_names.FR2;

                if (mFr2 == null) {
                    mFr2 = fr2.newInstance(MainActivity.this);
                    fm.beginTransaction().add(R.id.frLayout, mFr2, "fr2").commit();
                } else{
                    fm.beginTransaction().detach(mFr2).commit();
                    fm.beginTransaction().attach(mFr2).commit();

                }
            }
        });
        }
    }

<强> thumbnail.xml：

<RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1"
        android:id="@+id/btn_one"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="2"
        android:id="@+id/btn_two"
        android:layout_alignParentBottom="true"
        android:layout_alignRight="@+id/prgb_uni"
        android:layout_alignEnd="@+id/prgb_uni" />

    <ProgressBar
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/prgb_uni"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="40dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:id="@+id/frLayout"></FrameLayout>


</RelativeLayout>

它的作用：我们这里有一个基类，它使用视图表示和填充进度条来操作。它具有处理当前项（保存进度条值）的字段，每当我们在片段之间切换时，此字段被更新为Fragment1或Fragment2的相应值，这些片段具有静态字段以保存其自己的数据，因此可以更改和使用。

使用Thread和其他一些代码只是为了表明它的工作原理和更好的理解。

我希望它会有所帮助。

PoC - https://youtu.be/uKGeX40z_mA：）

如何在切换片段时保留进度条状态？

2 个答案: