Android的showDialog()、onPrepareDialog()和onCreateDialog()的关系

查了很多资料，研究了两天showDialog()、onPrepareDialog()和onCreateDialog()的关系，但都没有想明白，今晚看了Android的源代码才终于弄清楚这三者是什么关系......

----> showDialog()调用createDialog()和onPrepareDialog()，其中createDialog()调用onCreateDialog()。

import android.app.Activity;import android.app.Dialog;import android.app.ProgressDialog;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class Sample2_19_Activity extends Activity{    final int PROGRESS_DIALOG = 0;    final int INCREASE = 0;    final int MAX_COUNTER = 100;       ProgressDialog pd;    Handler hd;       @Override    public void onCreate(Bundle savedInstanceState)    {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);               Button bok = (Button) this.findViewById(R.id.Button01);        bok.setOnClickListener        (            new OnClickListener()            {                @Override                  public void onClick(View v)                {                    showDialog(PROGRESS_DIALOG);                                   }            }        );                hd = new Handler()        {            @Override            public void handleMessage(Message msg)  //必须重写此方法，用于接收数据            {                super.handleMessage(msg);                               switch(msg.what)                {                   case INCREASE:                     pd.incrementProgressBy(1);//进度每次加1                        if(pd.getProgress() >= MAX_COUNTER)                        {                            pd.dismiss();                                                        }                                         break;                }            }        };    }       @Override    public Dialog onCreateDialog(int id)    {        switch(id)        {              case  PROGRESS_DIALOG:                 pd = new ProgressDialog(this);                 pd.setMax(MAX_COUNTER);//设置最大值                 pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);                  pd.setTitle(R.string.title);//设置标题                 pd.setCancelable(false);//设置进度对话框不能用回退按钮关闭                     Log.d("kkk", "kkk");              break;        }               return pd;    }         @Override    //每次弹出对话框时被回调以动态更新对话框内容的方法    public void onPrepareDialog(int id, Dialog dialog)    {        super.onPrepareDialog(id, dialog);           switch(id)           {          case  PROGRESS_DIALOG:            pd.incrementProgressBy(-pd.getProgress());//对话框进度清零            new Thread()            {                  public void run()                  {                    while(true)                    {                          hd.sendEmptyMessage(INCREASE);                          if(pd.getProgress() >= MAX_COUNTER)                          {                              break;                          }                          try                          {                              Thread.sleep(40);                          }                          catch(Exception e)                          {                              e.printStackTrace();                          }                     }                  }                             }.start();          break;        }    }}

Android SDK源代码

public final void showDialog(int id) {        showDialog(id, null);}==================================================================================================public final boolean showDialog(int id, Bundle args) {        if (mManagedDialogs == null) {            mManagedDialogs = new SparseArray<ManagedDialog>();        }        ManagedDialog md = mManagedDialogs.get(id);        if (md == null) {            md = new ManagedDialog();            md.mDialog = createDialog(id, null, args);            if (md.mDialog == null) {                return false;            }            mManagedDialogs.put(id, md);        }               md.mArgs = args;        onPrepareDialog(id, md.mDialog, args);        md.mDialog.show();        return true;}================================================================================================== private Dialog createDialog(Integer dialogId, Bundle state, Bundle args) {        final Dialog dialog = onCreateDialog(dialogId, args);        if (dialog == null) {            return null;        }        dialog.dispatchOnCreate(state);        return dialog;}

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