Primer C++第五版 读书笔记(一) (如有侵权请通知本人,将第一时间删文) 1.1-2.2 章节 关于C++变量初始化: 初始化不是赋值,初始化的含义是创建变量时赋予其一个初始值,而赋值的含义是把对象的当前值擦除,以一个新值来替代. 定义一个名为a的int变量并初始化为0,有以下4种方法: int a = 0; int a = {0}; // 列表初始化 int a{0}; // 列表初始化 int a(0); 当列表初始化方法用于内置类型的变量时,如果初始值存在信息丢失的风险,则编译器…
一. Spring的bean默认是单例的 But sometimes you may find yourself working with a mutable class that does main-tain some state and therefore isn’t safe for reuse. In that case, declaring the class as asingleton bean probably isn’t a good idea because that obje…
一. 假设有如下三个类实现同一个接口,则自动装配时会产生歧义 @Component public class Cake implements Dessert { ... } @Component public class Cookies implements Dessert { ... } @Component public class IceCream implements Dessert { ... } @Autowired public void setDessert(Dessert de…
一. 1.SpEL expressions are framed with #{ ... } 2.SpEl的作用 Sp EL has a lot of tricks up its sleeves, including the following: The ability to reference beans by their ID s Invoking methods and accessing properties on objects Mathematical, relational…
一.用placeholder给bean运行时注入值的步骤 Spring取得placeholder的值是用${...} 1.声明placeholder bean (1)java方式 In order to use placeholder values, you must configure either a PropertyPlaceholder-Configurer bean or a PropertySourcesPlaceholderConfigurer bean. Starting wit…
一. The @Qualifier annotation is the main way to work with qualifiers. It can beapplied alongside @Autowired or @Inject at the point of injection to specify whichbean you want to be injected. For example, let’s say you want to ensure that theIceCream…
一. Spring honors two separate properties when determining which profiles are active:spring.profiles.active and spring.profiles.default . If spring.profiles.activeis set, then its value determines which profiles are active. But if spring.profiles.acti…
一. DataSource在应用和开发环境的产生方式不同,可以用srping 的profile管理 Spring’s solution for environment-specific beans isn’t much different from build-timesolutions. Certainly, an environment-specific decision is made as to which beans willand won’t be created. But rath…
1.When injecting properties and constructor arguments on beans that are created via component-scanning, you can use the @Value annotation, much as you saw earlierwith property placeholders. Rather than use a placeholder expression, however, youuse a…
一.EntityManagerFactory的种类 1.The JPA specification defines two kinds of entity managers: Application-managed—Entity managers are created when an application directly requests one from an entity manager factory. With application-managed entity manage…
一.SpringSecurity的模块 At the least, you’ll want to include the Core and Configuration modules in your application’s classpath. Spring Security is often used to secure web applications, and that’s certainly the case with the Spittr application, so you’l…
