详解Android中App的启动界面Splash的编写方法

时间:2021-11-08 09:48:08

一、splash界面的作用
用来展现产品的logo
应用程序初始化的操作
检查应用程序的版本
检查当前应用程序是否合法注册

二、界面的xml定义
写一个布局背景设置为产品的logo图片,再添加一个textview显示版本号。

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<textview
android:id="@+id/tv_splash_version"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textcolor="#000000"
android:textstyle="bold"
android:shadowdx="1"//阴影的偏移量
android:shadowdy="1"
android:shadowradius="0.2"//阴影的半径
android:shadowcolor="#ffff00"
android:text="版本:1.0"
android:textsize="16sp"
android:layout_centerinparent="true"/>

三、动态获取版本号的方法

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public string getappversion(){
  packagemanager pm = getpackagemanager();
  try {
    packageinfo info = pm.getpackageinfo(getpackagename(), 0);
    return info.versionname;
  } catch (namenotfoundexception e) {
    e.printstacktrace();
    //不可能发生;
    return "";
  }
}

四、链接服务器获取更新信息
升级提醒的对话框

 

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protected void showupdatedialog() {
 alertdialog.builder build = new builder(this);
 build.settitle("发现新版本");
 build.setmessage(description);
 build.setnegativebutton("立刻升级", new onclicklistener() {
 
   @override
   public void onclick(dialoginterface dialog, int which) {
     //升级的代码;
   };
 });
 build.setpositivebutton("下次再说", new onclicklistener() {
 
   @override
   public void onclick(dialoginterface dialog, int which) {
     dialog.dismiss();
 enterhome();
 
   }
 });
 build.show();

在子线程中请求服务器的代码 checkup()方法

 

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private void checkup() {
 new thread() {
   public void run() {
     message msg = message.obtain();
     long starttime = system.currenttimemillis();//启动该线程的系统时间
     try {
       //请求网络的代码
       url url = new url(getstring(r.string.serverurl));
       httpurlconnection conn = (httpurlconnection) url
           .openconnection();
       conn.setrequestmethod("get");//请求方法
       conn.setconnecttimeout(4000);//超时时间
       int code = conn.getresponsecode();//返回码200请求成功
       if (code == 200) {
         inputstream is = conn.getinputstream();
         string result = streamtools.readfromstream(is);
         log.i(tag, "联网成功" + result);
         jsonobject obj = new jsonobject(result);//解析json字符串
         string version = (string) obj.get("version");//版本信息
         description = (string) obj.get("description");//描述信息
         apkurl = (string) obj.get("apkurl");
         if (getappversion().equals(version)) {
           msg.what = enter_home;
         } else {
           msg.what = show_update_dialog;
 
         }
       }
     } catch (malformedurlexception e) {
 
       e.printstacktrace();
       msg.what = url_error;
     } catch (ioexception e) {
       e.printstacktrace();
       msg.what = network_error;
     } catch (jsonexception e) {
       e.printstacktrace();
       msg.what = json_error;
     } finally {
       handler.sendmessage(msg);
       long endtime = system.currenttimemillis();//该线程执行完毕的时间
       long dtime = endtime-starttime;//该线程的阻塞时间
       if (dtime<3000) {
         try {
           thread.sleep(3000-dtime);//若该线程的阻塞时间小于三秒继续睡眠到三秒
         } catch (interruptedexception e) {             
           e.printstacktrace();
         }
       }
     }
   }
 }.start();
 
 }
handler
 
 private handler handler = new handler() {
 
 @override
 public void handlemessage(message msg) {
   // todo auto-generated method stub
   super.handlemessage(msg);
   switch (msg.what) {
   case show_update_dialog:
     showupdatedialog();
     break;
   case enter_home:
     toast.maketext(getapplicationcontext(), "", 0).show();
     enterhome();
     break;
   case url_error:
     toast.maketext(getapplicationcontext(), "url_error", 0).show();
     enterhome();
     break;
   case network_error:
     toast.maketext(getapplicationcontext(), "network_error", 0).show();
     enterhome();
     break;
 
   case json_error:
     toast.maketext(getapplicationcontext(), "json_error", 0).show();
     enterhome();
     break;
   }
 }
};

五、下载文件(使用afinal框架)并调用系统安装工具安装apk

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if (environment.getexternalstoragestate().equals(environment.media_mounted)) {
    finalhttp finalhttp = new finalhttp();
      finalhttp.download(apkurl,environment.getexternalstoragedirectory().getabsolutepath()+
       "/mobilesafe2.0.apk" , new ajaxcallback<file>() {
 
        @override
        public void onloading(long count, long current) {
          super.onloading(count, current);
          tv_uapdate_info.setvisibility(view.visible);
          int progress =(int) (current*100/count);
              tv_uapdate_info.settext("下载进度:"+progress+"%");
        }
 
        @override
        public void onfailure(throwable t, int errorno,
            string strmsg) {
          t.printstacktrace();
          toast.maketext(getapplicationcontext(), "下载失败", 0).show();
          enterhome();
 
          super.onfailure(t, errorno, strmsg);
        }
 
        @override
        public void onsuccess(file t) {
 
          super.onsuccess(t);
          installapk(t);
 
        }
 
        private void installapk(file t) {
          intent intent = new intent();//自动安装程序可调用该段代码
          intent.setaction("android.intent.action.view");
          intent.addcategory("android.intent.category.default");
          intent.setdataandtype(uri.fromfile(t), "application/vnd.android.package-archive");
          startactivity(intent);           
        }
 
      });
 
    }else{
      toast.maketext(getapplicationcontext(), "请插入内存卡再试",0).show();
      return;
 
    }

其他:

1、显示4.0的样式:方式是去掉功能清单里的activity对应的android:theme;
放到application里面;

2、当splash页面弹出升级提示框过滤点击返回的是两种方式:

builder.setcancelable(false);
设置setoncancellistener 当触屏的时候直接进入主页面

对话框是挂载在activity上面的,如果activity不存在,对话框就不能被创建。
getapplicationcontext();生命周期长,只要应用还存活它就存在;this 生命周期短,只要activity不存在了,系统就会回收
其中:getbasecontext(),getapplication(),getapplicationcontext(); 都不能放在alertdialog做上下文;

3.splash用来宣传和隐藏程序启动细节是很有用的。
 
用handler的实现方法如下:(也可以用线程实现,不推荐)
定义一个activity,用来显示你的图片,其中最重要的就是定义一个handler,用来发送和接收消息:

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public class welcomeactivity extends activity 
{
  //定义一个handler,用来接收延迟发送的信息-启动activity
  private handler handler = new handler()
  {
    @override
    <span style="color: #ff0000;">public void handlemessage(message msg) </span>
    {
      // todo auto-generated method stub
      super.handlemessage(msg);
      switch(msg.what)
      {
      case 0x123:
        intent intent = new intent(welcomeactivity.this
            onlineexamactivity.class);
        startactivity(intent);
        finish();
      }
    }
  };

 
在oncreate()方法中,用handler发送消息,延迟3000毫秒:
 

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@override
  protected void oncreate(bundle savedinstancestate)
  {
    // todo auto-generated method stub
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.welcome_activity);
    start();
  }
 
  private void start() 
  {
    <span style="color: #ff0000;">handler.sendemptymessagedelayed(0x123, 3000);</span>
  }

 把你的图片放到布局文件中作背景即可。