Conceptual summary of the concept of great God in Java theory

I personally think that Java is able to endure, there is a very important reason is: Java theory always give a person, although do not know what is, but feel very strong appearance. This alone, he has gone beyond many other languages, at least when bragging is always a lot of conversation.

Not much nonsense to say (in fact, a whole article is nonsense), today to summarize, some of the concept of personal insight (are selected from the project, the limited number of capacity is limited), please advise!

　　

1. Object-Oriented Programming

This is not a special thing, but it is the Java of the body of the book. Everything is the object of everything. The object-oriented, basic function benefits are encapsulation, inheritance, polymorphism and so on.

2. Plane-oriented programming

The main purpose of AOP is to extract the facets in the process of business processing, which is faced with a step or stage in the process of processing in order to obtain the isolation effect of low coupling between parts of the logic process.

3. Design mode

In general, design patterns fall into three broad categories:
Create five types of models: Factory method mode, abstract Factory mode, singleton mode, builder mode, prototype mode.
Structure mode, a total of seven kinds: Adapter mode, adorner mode, proxy mode, appearance mode, bridging mode, combined mode, enjoy the meta-mode.
There are 11 types of behavioral Patterns: Strategy mode, template method mode, observer mode, iteration sub-mode, responsibility chain mode, Command mode, Memo mode, state mode, visitor mode, mediator mode, interpreter mode.

4. Reflection mechanism

The reflection mechanism is in the running state, for any class, can know all the properties and methods of this class, for any one object, can call any of its methods and properties; This dynamically acquired information and the ability to dynamically invoke the method of the object is called the reflection mechanism of the Java language.

5. Package mechanism

To better organize classes, Java provides a package mechanism that distinguishes the namespace of the class name (other languages may be called namespaces).
1, the function of similar or related classes or interfaces organized in the same package, convenient for the search and use of the class.
2, like the folder, the package also uses the tree directory storage. The class names in the same package are different, and the names of the classes in different packages can be the same, and the package name should be distinguished when calling two classes of the same class name in different packages. Therefore, packages can avoid name collisions.
3. The package also restricts access, and classes that have access to the package can access the classes in a package.
Java uses the package as a mechanism to prevent naming conflicts, access control, to provide search and locate classes (class), interfaces, enumerations (enumerations), and annotations (annotation), and so on.

6. Component Technology

A component is a reusable set of code that is capable of doing something and provides several interfaces that use this functionality, and plainly is a collection of common class files.

7. Noun Abbreviations and explanations

IML is the project configuration file for IntelliJ idea, which is the configuration information for the current PROJEC, such as specifying the compilation directory, configuration directory, and so on.
. Project is a project file in which the structure of the project is defined, such as the location of the Lib, the location of the SRC, and the location of the classes.
The location of the. CLASSPATH defines the $classpath you use for this project at compile time.
Pom.xml, MAVEN's core configuration file.
Web. XML, the core configuration file for the website project.

Filter: Filters, which are used for processing, such as writing logs, processing parameters, before or after request entry.
Inteceptor is generally used for permission validation, as well as some common code for processing style localization.
Servlet:java the core processing class of the Web, the third-party framework is to implement powerful and convenient functions by taking over the way of this class.

Xmlns:xml the abbreviation for namespaces, the Chinese name is the XML (a subset of the standard generic markup language) namespaces.
Xmlns:xsi: The element or attribute in this namespace must be written in xsi: this way, such as SchemaLocation is one of his attributes, so write xsi:schemalocation, and the default namespace is not like XSi this, In fact, there is a professional name of the XML tag called QName, and if there is no previous xsi: this is generally called NCName. So you see the <dependency> in MVN this is the element under the default namespace, and the last line represents the schema file that defines the namespace as a reference, So that the Eclipse type tool can parse and verify that your XML file conforms to the syntax specification. Equivalent to <import namespace= "xxx" schemalocation= "xxx.xsd"/>.
XSD: Refers to the XML Structure definition (XML Schemas definition)
Dtd:document type definition, chinese meaning "document class definitions". A DTD is a twofold task: it helps you write legitimate code, on the other hand, it lets the browser display the code correctly.

8. Java Beans

JavaBean is a Java component that conforms to a specification, that is, a Java class. It must meet the following specifications:
1) must have a default constructor for a 0 parameter
2) The Get and set methods must be used, and the fields of the class must be accessed through the get and set methods. (Get method without parameters, set method has parameters)

9. Load Path

Classpath*: occurs in order to load the same file from multiple jar files.
Classpath: Only the first file found can be loaded.

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Conceptual summary of the concept of great God in Java theory