Shulou(Shulou.com)06/03 Report--

Core idea: object-oriented programming, inheritance, high compatibility (code portability), avoid duplication, open source.

Java origin and development details will not be introduced, Java is a high-level development language, similar to C++, syntax and C++ have a lot of similarities, but do some optimization, mainly in the code to write program optimization, avoid memory leakage, avoid pointer complex misuse, etc., Java can not directly operate pointers, hidden.

Java programs from writing to running

A Write the correct Java code.java file-->B Compile it into a class file.class file through tools--> C Load the class file in the jvm virtual machine running in the system--> D Jvm reads the main method in the class file to start a system process--> E Finish Java program and start running.

There is a process in the D process--> jvm virtual machine loads the class file, translates the.class into machine code (similar to the system bottom instruction), and the same class file, the machine code translated in the window environment is different from the machine code translated in the Linux environment: the root of strong code portability (jvm virtual machine)

Members in Java: jvm virtual machines,jre,jdk

jvm virtual machine

Java code loader, compiler, engine load (read).class file

The virtual machine mentioned above translates the class file into a machine code that the system can recognize, so jvm is a necessary part of Java programs, and it also shows that different systems, jvm virtual machine versions are different.

Jvm virtual machine is composed of C language and assembly language, which is the foundation of Java program running. Java program running first needs to run jvm.

Java Virtual Machine (JVM) is part of JRE. It is an imaginary computer, realized by simulating various computer functions on an actual computer. JVM has its own perfect hardware architecture, such as processor, stack, register, etc., and also has corresponding instruction system. The most important feature of Java is that it runs across platforms. JVM is used to support cross-platform implementation independent of operating systems.

jre(Java Runtime Environment)

Java program runtime environment, which contains the jvm virtual machine. Java programs need the environment they need to run in, i.e. jre.

jdk (Java Development Kit)

Java Software Development Kit (SDK) Java software development environment, tools programmers need to write Java programs. The difference with jre includes jre, with more compilation tools, such as compiling.java files into.class files.

Java development in common technical ideas, frameworks, tools

technical thought

object-oriented

Everything in Java can be seen as an object, anything from the object point of view, problem solving from the object point of view.

inheritance

In Java objects can be inherited and will use all common properties, common methods of the inherited object. The inheritor is a subclass, the inheritor is a parent class, and the top-level superclass of all objects in Java is Object.

polymorphism

Polymorphism is the ability of the same behavior to have many different manifestations or forms.

Polymorphism is when different instances of the same interface perform different operations. Specifically, it involves knowledge of interfaces in Java.

multithreading

One thread handles one thing, and multiple threads execute their own things among colleagues without affecting each other.

high concurrency

In the case of limited hardware resources, a large number of threads start running and processing things in a short time.

long connection

The technology needed to exchange data with frequent communication terminals, such as database connections, is generally a long connection; characteristics: fewer connections, frequent communication. Want to pair of short connections: the number of connections, the same connection in a short period of time less continuous communication.

nio

Non-blocking io, to solve the problem of network data transmission blocking, when both ends of the communication connection, not necessarily immediately accept data, this will cause threads waiting to send data caused by blocking, nio provides buffer, there is data when the communication data through the channel to write buffer, no data is executed first other threads, to avoid blocking.

framework

spring

SpringFramework, Spring. IoC(Inversion of Control) and AOP(Aspect Oriented Programming) are popular technical frameworks and framework design ideas in Java. Adhering to the idea of high cohesion and low coupling. It is non-invasive and compatible with all other technical frameworks. (A concrete implementation of avoiding duplication of wheel building)

springmvc

Spring MVC is a successor to SpringFrameWork and has been integrated into Spring Web Flow. Spring Framework provides a full-featured MVC module for building Web applications (from Baidu). Web Framework, Front Control Layer Access Framework.

mybatis

Lightweight persistence layer framework, persistence layer development more efficient framework, in the iteration of ×× hair, network projects used more.

MyBatis was originally an apache open source project iBatis. In 2010, this project was migrated from apache software foundation to google code and renamed MyBatis. Moved to Github in November 2013. MyBatis is an excellent persistence layer framework that supports custom SQL, stored procedures, and advanced mappings. MyBatis avoids almost all of the JDBC code and manual parameter setting and result set retrieval. MyBatis can configure and map native information using simple XML or annotations, mapping interfaces and Java POJOs(Plain Ordinary Java Objects) to records in the database. (from Baidu)

hibernate

Hibernate is an open source object-relational mapping framework, it carries out a very lightweight object encapsulation of JDBC, it establishes a mapping relationship between POJO and database tables, is a fully automatic orm framework, hibernate can automatically generate SQL statements, automatic execution, so that Java programmers can use object programming thinking to manipulate databases at will. (from Baidu)

springboot

Springboot is an efficient and rapid project development framework based on multi-technology integration. The core is still spring, but the integration encapsulates many other technologies (such as redis, mybatis, etc.), eliminating some repetitive and cumbersome processes in project development.

springcloud

Springcloud is a distributed architecture technology. Springcloud is built on the basis of Springboot. It is mainly a distributed development architecture that centrally manages Springboot projects in a distributed environment.

netty

Nio technology implementation framework.

tool

eclipse

Tools for developing projects using Java, C, etc.

idea

Java, C and other languages used to develop the project tools, and eclipse is a relatively easy to use project development tools, even more powerful than eclipse features, but need to pay.

maven

Project development jar resource dependency management tool, project packaging tool, make project development more efficient.

tomcat

Web project running container, now springboot framework with integrated tomcat, using springboot development can not require additional configuration tomcat.

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