properties | 易学教程

Mybatis入门(四)配置优化(一)

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这一章主要实验Mybatis的引入外部配置文件，属性（properties）这个属性都是可外部配置且可动态替换的，既可以在典型的 Java 属性文件中配置，亦可通过 properties 元素的子元素来传递。这是官方的。来实践一下：根据官方要求先创建一个db.properties外部文件里面写配置属性： driver=com.mysql.cj.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis?useSSL=true&UseUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC username=root password=root 在到mybatis-config.xml文件里设置需要添加propertion标签来引入： <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">  <configuration> <!--引入外部配置文件之后，driver的值都需要用${}来引用db

Spring Cloud Alibaba Nacos

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1. Spring Cloud Alibaba 介绍 Spring Cloud Alibaba 为分布式应用程序开发提供了一站式解决方案。它包含了开发分布式应用程序所需的所有组件，使得你可以轻松地使用Spring Cloud开发应用程序。使用Spring Cloud Alibaba，只需要添加一些注释和少量配置即可将Spring Cloud应用程序连接到Alibaba的分布式解决方案，并使用Alibaba中间件构建分布式应用程序系统。特性：流量控制和服务降级：Sentinel进行流量控制，断路和系统自适应保护。服务注册和发现：实例可以在Nachos中注册，并且客户端可以使用Spring管理的Bean发现实例。支持Ribbon。分布式配置：使用Nacos作为数据存储。事件驱动：建立与Spring Cloud Stream RocketMQ Binder连接的高度可扩展的事件驱动型微服务。消息总线：利用Spring Cloud Bus RocketMQ链接分布式系统的节点。分布式事务：支持高性能、易于使用的分布式事务。 Dubbo RPC ：通过Dubbo RPC扩展Spring Cloud服务之间调用的通信协议。阿里云对象存储：阿里云对象存储服务（OSS）是一种加密、安全、经济高效且易于使用的对象存储服务，可让您在云中存储，备份和存档大量数据。

Google Style Guide properties for getters and setters

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问题 I'm curious about one of the recommendations in the Google Python style guide concerning properties. In it, they give the following example: class Square(object): """A square with two properties: a writable area and a read-only perimeter. To use: >>> sq = Square(3) >>> sq.area 9 >>> sq.perimeter 12 >>> sq.area = 16 >>> sq.side 4 >>> sq.perimeter 16 """ def __init__(self, side): self.side = side def __get_area(self): """Calculates the 'area' property.""" return self.side ** 2 def ___get_area

Undefined values with new Array() in JavaScript

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问题 Looking at some javascript code, I saw (something like) this: var arr = Array.apply(null, {length: 10}); Reading the MDN documentation for Function.prototype.apply(), I learnt that although it usually expects an array as its second argument which is an array of the arguments to be passed to the invoked function, you can also use any kind of object which is array-like, so in practice this means it's going to have a property length and integer properties in the range (0...length). So from what

android学习常见错误

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Unable to resolve target 'android-7' Unable to resolve target 'android-7' 解决方案：修改工程目录下的default.properties文件里的内容target=android-7改成target=android-8(或者其他版本)就可以了，最好用txt打开，然后修改之后保存，运行就可以了。错误提示:The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files 今天在eclipse3.2+myeclipse5.1+tomcat5.5重新部署时出了这问题.搞了很久才找到原因.解决办法写出来分享: 出现以上错误的原因是居然是装jdk5时了多装了个 jre。本来 Eclipse 在建立项目时，会自动参照你的 jre 路径，但多个版本就没办法加载了。

Spring MVC best way to populate drop down list - properties file?

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问题 I want to populate a drop down list and I do not want to keep going to the database. I was thinking to have my country list or language list in a properties file. That way I could read it in, and then assign that to a variable. I could then return that through the ModelAndView type. Is this a good approach? I am not sure how else to store static data. I do not want to keep it in a class because it will be harder to update it if there needs to be a change. 回答1: got an answer! If I got a list

Objective C - Using an accessor if It does nothing different

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问题 In objective c, if the using the getter and directly accessing the ivar do exactly the same thing, no lazy loading code in the getter, all it does is returns the ivar, would you still use the accessor or access the ivar directly since there is no difference? Why? EDIT: I'm talking about inside the class. 回答1: There is a small performance advantage to be enjoyed by using the ivar directly. However, to avoid confusion, I typically prefix my ivars with _ on the front, and then synthesize a

python - why is read-only property writable?

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问题 I am trying to define a class with a read-only property in a Python; I followed Python documentation and came up with the following code: #!/usr/bin/python class Test: def __init__(self, init_str): self._prop = init_str @property def prop(self): return self._prop t = Test("Init") print t.prop t.prop = "Re-Init" print t.prop Now when I try to execute the code though I am expecting error/exception I see it getting executed normally: $ ./python_prop_test Init Re-Init My Python version is 2.7.2.

Detect access modifier type on a property using Reflection

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问题 I have written some code to look at properties using reflection. I have retrieved a list of properties from the class using reflection. However I need to find out if the property is public or protected. eg: public string Name{get;set;} protected int Age{get;set;} The PropertyInfo class does not seem to expose this information about the property. Is there another way to do this? 回答1: Since properties are just syntactic sugar over a pair of get / set methods, there's no such thing as

Detect access modifier type on a property using Reflection

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