handler | 易学教程

Will handler inside a method leak memory?

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问题 I know handler declared in a class may leak memory since it holds a reference to its outer class. In this case, we should use static nested class with weak reference. But What if a handler is declared inside a method. I faced below case and not sure is it a correct implementation. Could someone please explain or give me a hint? I even don't know what I should search for. private void methodA(){ Handler handler = new Handler(); handler.postDelayed(new Runnable() { @Override public void run() {

MySQL rollback in handler

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问题 I have a stored procedure where I'd like to rollback in case anything goes wrong. In order to do that I'm using a EXIT HANDLER like this: DECLARE EXIT HANDLER FOR sqlexception begin ROLLBACK; end; But in this way, when I call this stored procedure, in case of any errors, the stored procedure succeed and I don't know what was the actual problem. I want the client (php) to log the error in order to troubleshoot it. So I modify in this way: DECLARE EXIT HANDLER FOR sqlexception begin get

Glide生命周期原理

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本文首发于 vivo互联网技术微信公众号链接： https://mp.weixin.qq.com/s/uTv44vJFFJI_l6b5YKSXYQ 作者：连凌能 Android App中图片的展示是很基本也很重要的一个功能，在Android平台上有很多的图片加载解决方案，但是官方认可的是Glide。Android App的页面是有生命周期的，Glide比较好的一个功能就是具有生命周期管理功能，能够根据页面和APP的生命周期来管理图片的加载和停止，也开放接口供用户在内存紧张时手动进行内存管理。本文重点是生命周期源码的分析，不会从简单的使用着手。一、综述这是Glide源码分析的第二篇文章，第一篇是《Glide缓存流程》，从资源的获取流程对源码进行分析。本篇会聚焦于生命周期模块的原理。开始之前先思考下面这几个问题： Glide怎么实现页面生命周期？ Glide为什么对Fragment做缓存？ Glide如何监听网络变化？ Glide如何监测内存？二、Glide生命周期传递先来看with函数的执行, 会构造glide单例，而 RequestManagerRetriever在initializeGlide中会进行构造。 // Glide.java public static RequestManager with(@NonNull Activity activity) {

System.NullReferenceException When checking if != null

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问题 I'm using an ASHX handler, i want the handler to check if Session != null. if (context.Session["Username"] != null) And i get this error pointing this line: System.NullReferenceException: Object reference not set to an instance of an object. What's the problem? 回答1: if (context.Session["Username"] != null) Does your handler implement IRequiresSessionState? Otherwise Session might not be available. From MSDN: Specifies that the target HTTP handler requires read and write access to session

vue.js 查看百度文库文档

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<template> <div> <div id="reader"></div> </div></template> <script>　　//doc.js文件地址 http://static.bcedocument.com/reader/v2/doc_reader_v2.js import doc from '../../libs/doc'; export default { data(){　　　　　　return{　　　　　　　　loading:false　　　　　　}　　　　　　　　　　　}, created() { this.getInfo(this.$route.query.id); }, methods:{ getInfo(id){ this.loading = true; this.$api.recommend.show(id).then(result =>{ if(result.success){ let textId =result.result.content.id; 　　　　　　　　　　　　　　　　//获取到文档id 请求接口获取docId，host，token三个变量　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　this.$api.recommend.getDoc(textId).then(res =>{ // console.log(res)

how to handle sleep mode enter in android?

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问题 I didn't find it anywhere, how can I handle entering sleeping mode in android? I want to do something when android device entered to the sleep mode? Is this possible or is there anyway to handle it? 回答1: Just make this by using BroadCastReceivers for system-calls (wakeup/sleep) Android - how to receive broadcast intents ACTION_SCREEN_ON/OFF? 回答2: how can I handle entering sleeping mode in android? Generally, you don't. There is nothing you need to do related to sleep mode. I want to do

15-ChannelInitializer

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文章目录 ChannelInitializer 一、继承关系二、源码 2.1 注释 2.2 源码分析 2.3 handlerAdded和channelRegistered 三、使用示例 ChannelInitializer ChannelInitializer 是一种特殊的 ChannelHandler，它也是一种 ChannelInboundHandler，它提供了在通道注册到 EventLoop 后初始化通道的简单方法；其主要目的是在某个 Channel 注册到 EventLoop 后，对这个 Channel 执行一些初始化操作。在初始化完成之后，ChannelInitializer 会将自己从 Pipeline 中移除，不会影响后续的操作。作用：在某个Channel注册到EventLoop后，对这个Channel执行一些初始化操作，初始化操作完成后会将自身从Pipeline中移除。一、继承关系二、源码 2.1 注释源码注释如下： /** * 一个特殊的ChannelInboundHandler，提供了一个便捷的方式在Channel注册到EventLoop的时候来初始化这个Channel * A special {@link ChannelInboundHandler} which offers an easy way to initialize a {@link

How to kill a thread and handler before going to new activity

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问题 Hey all - this code might be a bit messy in the way I'm trying to clean up the handler as I've been trying to track down where the crash happens... I've got a dialog activity that is showing a password entry with a progressbar being animated by a thread and handler... It seems that when I'm attempting to see if the progressbar is done, and trying to kill the thread, the way I'm doing this is messing something up when I try to go to a new activity - ie in a way calling a function and not

how to select lines in Mysql while a condition lasts

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问题 I have something like this: Name.....Value A...........10 B............9 C............8 Meaning, the values are in descending order. I need to create a new table that will contain the values that make up 60% of the total values. So, this could be a pseudocode: set Total = sum(value) set counter = 0 foreach line from table OriginalTable do: counter = counter + value if counter > 0.6*Total then break else insert line into FinalTable end As you can see, I'm parsing the sql lines here. I know

golang http server源码解析

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golang 版本：1.12.9 简单的HTTP服务器代码： package main import ( "net/http" ) type TestHandler struct { str string } func (th *TestHandler)ServeHTTP(w http.ResponseWriter, r *http.Request){ w.Write([]byte(string(th.str+",welcome"))) } func main(){ http.Handle("/", &TestHandler{"Hi,Stranger"}) http.HandleFunc("/test",func(w http.ResponseWriter,r *http.Request){ w.Write([]byte("Hi,Tester")) }) http.ListenAndServe(":8000",nil)} 在浏览器输入“http://127.0.0.1:8000”得到输出“Hi,Stranger,welcome”；输入“http://127.0.0.1:8000/test”得到输出“Hi,Tester” handler的注册 handler的相关方法如下： func NewServeMux() *ServeMux func (mux *ServeMux)