【安卓札记】使用DialogFragment托管dialog

普通的AlertDialog在横竖屏切换时会被销毁，如果dialog上面有数据，也将丢失。解决方案是使用DialogFragment。
使用dialogFragment通常需要复写两个方法：

onCreateView(LayoutInflater, ViewGroup, Bundle)
onCreateDialog(Bundle)

如果你想自定义dialog样式，只需要复写onCreateView，注入一个自定义的view即可，然后通过调用DialogFragment#show()方法即可。

这里我们不需要自定义，只需要托管AlertDialog即可,所以我们仅仅需要复写onCreateDialog方法。在这个方法内部我们需要通过AlertDialog.Builder构建一个dialog并返回，dialog的参数可以通过setArguments注入。具体代码如下：

package com.taobao.dialogfragmentdemo;import android.app.Dialog;import android.content.DialogInterface;import android.os.Bundle;import android.support.annotation.NonNull;import android.support.v4.app.DialogFragment;import android.support.v7.app.AlertDialog;public class AlertDialogFragment extends DialogFragment{    private static final String PARAM_TITLE = "title";    private static final String PARAM_CONTENT = "content";    private static DialogCallback mCallback;    public AlertDialogFragment()    {    }    public static AlertDialogFragment newInstance(String title,String content,DialogCallback callback)    {        AlertDialogFragment instance = new AlertDialogFragment();        Bundle bundle = new Bundle();        bundle.putString(PARAM_TITLE,title);        bundle.putString(PARAM_CONTENT,content);        instance.setArguments(bundle);        mCallback = callback;        return instance;    }    @NonNull    @Override    public Dialog onCreateDialog(Bundle savedInstanceState)    {        Bundle params = getArguments();        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());        builder.setTitle(params.getString(PARAM_TITLE));//没有做非空判断，按需添加        builder.setMessage(params.getString(PARAM_CONTENT));        builder.setPositiveButton("确定", new DialogInterface.OnClickListener()        {            @Override            public void onClick(DialogInterface dialog, int which)            {                if(mCallback != null)                    mCallback.onPostiveClick();            }        });        builder.setNegativeButton("取消", new DialogInterface.OnClickListener()        {            @Override            public void onClick(DialogInterface dialog, int which)            {                if(mCallback != null)                    mCallback.onNegativeClick();            }        });        return builder.show();    }    public interface DialogCallback    {        public void onPostiveClick();        public void onNegativeClick();    }}

想使用也很简单：

AlertDialogFragment dialog = AlertDialogFragment.newInstance("标题", "这是fragment托管的alertdialog", new AlertDialogFragment.DialogCallback()        {            @Override            public void onPostiveClick()            {                Toast.makeText(MainActivity.this,"确定",Toast.LENGTH_SHORT).show();            }            @Override            public void onNegativeClick()            {                Toast.makeText(MainActivity.this,"取消",Toast.LENGTH_SHORT).show();            }        });        dialog.show(getSupportFragmentManager(),"dialog");

还可以通过DialogFragment#show的第二个参数tag来找到对应的dialogFragment:

 FragmentTransaction transaction = getSupportFragmentManager().beginTransaction(); Fragment prevDialog = getSupportFragmentManager().findFragmentByTag("dialog"); if(prevDialog != null) {      transaction.remove(prevDialog); }