项目需求：接受其他app发过来的暗码广播，接收到广播后显示一些信息，由于再Receiver里面不能使用AlertDialog，考虑到使用activity替换，留下笔记以供后续查看

1、增加style

res/values/styles.xml

<style name="dialogstyle" parent="android:style/Theme.Dialog" >
        <!--设置dialog的背景-->
        <item name="android:windowBackground">@android:color/transparent</item>
        <!--设置Dialog的windowFrame框为无-->
        <item name="android:windowFrame">@null</item>
        <!--设置无标题-->
        <item name="android:windowNoTitle">true</item>
        <!--是否浮现在activity之上-->
        <item name="android:windowIsFloating">true</item>
        <!--是否半透明-->
        <item name="android:windowIsTranslucent">true</item>
        <!--设置窗口内容不覆盖-->
        <item name="android:windowContentOverlay">@null</item>
        <!--设置动画，在这里使用让它继承系统的Animation.Dialog-->
        <item name="android:windowAnimationStyle">@android:style/Animation.Dialog</item>
        <!--背景是否模糊显示-->
        <item name="android:backgroundDimEnabled">true</item>
    </style>

layout文件

<?xml version="1.0" encoding="utf-8"?>
<!--
 Copyright (c) 2014-2015 Qualcomm Technologies, Inc.  All Rights Reserved.
 Qualcomm Technologies Proprietary and Confidential.
 -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/transparent"
    android:layout_gravity="center" >

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:padding="15dp"
        android:background="@android:color/white"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/alert_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:layout_marginTop="1dp"
            android:textColor="@android:color/black"
            android:textSize="24sp" />

        <TextView
            android:id="@+id/alert_info"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:layout_marginTop="5dp"
            android:textColor="@android:color/black"
            android:textSize="18sp" />

        <TextView
            android:id="@+id/alert_ok"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:layout_gravity="end"
            android:textColor="@android:color/holo_blue_light"
            android:text="@android:string/ok"
            android:textSize="18sp"
            />
    </LinearLayout>


</RelativeLayout>

import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.TextView;

/**
 * Created by root on 12/24/16.
 */

public class SecretCommonActivity extends Activity {
    private TextView mTitletextView;
    private TextView mInfoTextView;
    private TextView mOKTextView;

    private final static String ALERT_TITLE = "alert_title";
    private final static String ALERT_INFO = "alert_info";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

       /* WindowManager.LayoutParams params = getWindow().getAttributes();
        params.flags |= WindowManager.LayoutParams.FLAG_FULLSCREEN;
        getWindow().setAttributes(params);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        requestWindowFeature(Window.FEATURE_NO_TITLE);*/

        setContentView(R.layout.secret_common);

        mTitletextView = (TextView)findViewById(R.id.alert_title);
        mInfoTextView = (TextView)findViewById(R.id.alert_info);
        mOKTextView = (TextView)findViewById(R.id.alert_ok);

        mTitletextView.setText(getIntent().getStringExtra(ALERT_TITLE));
        mInfoTextView.setText(getIntent().getStringExtra(ALERT_INFO));

        mOKTextView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SecretCommonActivity.this.finish();
            }
        });
    }
}

3、AndroidManifest.xml增加使用style

+        <activity
+            android:name=".SecretCommonActivity"
+            android:label="@string/blank"
+            android:icon="@drawable/alert_info"
+            android:theme="@style/dialogstyle"
+            android:screenOrientation="portrait" >
+        </activity>

Intent intent = new Intent(context, SecretCommonActivity.class);
        intent.putExtra(ALERT_TITLE, "Version Info");
        intent.putExtra(ALERT_INFO, versionStr);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_NO_HISTORY | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
        try{
            context.startActivity(intent);
        } catch (Exception e) {
            e.printStackTrace();
        }

注：

增加flag ： Intent.FLAG_ACTIVITY_NO_HISTORY | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS是为了不在最近列表中显示该activity

附：AlertDialog的使用方法

AlertDialog alert = new AlertDialog.Builder(context)
                .setTitle("Version Info")
                .setMessage(versionStr)
                .setPositiveButton(android.R.string.ok, null)
                .setCancelable(false)
                .show();