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java word meaning

java: [ 'd?ɑ:v? ]

n. 1. Java Island (Indonesia)

2. Coffee from Java

3. Computer application development language on the Internet

Example sentences and usage:

1. An Australian-administered island in the eastern Indian Ocean south of Java. It was annexed by Great Britain in1888 and came under Australian sovereignty in1958.

Christmas Island is an island in the eastern Indian Ocean south of Java, under the jurisdiction of Australia. Annexed by Britain in 1888, sovereignty returned to Australia in 1958

2. A volcanic island of Indonesia between Sumatra and Java. A violent explosion in August1883 blew the island apart and caused a tidal wave that killed more than36, 000 people.

Krakatau is located on a volcanic island between Sumatra and Java. In August 1883, a violent eruption of the island's volcano ripped the island apart and triggered a tsunami that killed more than 36,000 people.

3. He pictured to himself what it might be like to live in Java.

He imagined what it would be like to live in Java.

4. A web object can be a web page (or part thereof), an image, plain file , a directory, a Java applet, or CGI script.

A Web object can be a web page (or part of it), an image, a plain text file, a directory, a Java applet or CGI manuscript.

English explanation:

Noun java:

1. an island in Indonesia south of Borneo; one of the world's most densely populated regions

2. a beverage consisting of an infusion of ground coffee beans

Synonym: coffee

3. a simple platform-independent object-oriented programming language used for writing applets that are downloaded from the World Wide Web by a client and run on the client's machine

Introduction to Java

Java is a Java programming language launched by Sun Microsystems in May 1995 (below Java language for short) and the general name of the Java platform. The HotJava browser (supporting Java applets) implemented in Java shows the charm of Java: cross-platform, dynamic Web and Internet computing.

Since then, Java has been widely accepted and promoted the rapid development of the Web. Commonly used browsers now support Java applets. On the other hand, Java technology is also constantly updated.

The Java platform consists of the Java Virtual Machine (Java Virtual Machine) and the Java Application Programming Interface (API). The Java Application Programming Interface provides a standard interface for Java applications that is independent of the operating system and can be divided into basic parts and extended parts. After a Java platform is installed on the hardware or operating system platform, Java applications can run. Now the Java platform has been embedded in almost all operating systems. In this way, Java programs can be compiled only once and run on various systems. The Java Application Programming Interface has evolved from version 1.1x to version 1.2. The currently commonly used Java platform is based on Java1.4, and the latest version is Java1.6.

Java is divided into three systems: JavaSE, JavaEE, and JavaME.

Java language

Java language is an object-oriented programming language that supports network computing. Java language absorbs the advantages of Smalltalk language and C++ language, and adds other features, such as supporting concurrent programming, network communication, and multimedia data control. The main features are as follows:

1. The Java language is simple. The syntax of the Java language is very close to the C language and C++ language, making it easy for most programmers to learn and use Java. On the other hand, Java discards those features of C++ that are rarely used, difficult to understand, and confusing, such as operator overloading, multiple inheritance, and automatic casts. In particular, the Java language does not use pointers and provides automatic garbage collection so that programmers do not have to worry about memory management.

2. The Java language is object-oriented. The Java language provides primitives such as classes, interfaces and inheritance. For the sake of simplicity, it only supports single inheritance between classes, but supports multiple inheritance between interfaces, and supports the implementation mechanism between classes and interfaces (the keyword is implements) . The Java language fully supports dynamic binding, while the C++ language only uses dynamic binding for virtual functions. In short, the Java language is a pure object-oriented programming language.

3. The Java language is distributed. The Java language supports the development of Internet applications. Among the basic Java application programming interfaces, there is a network application programming interface (java.net), which provides class libraries for network application programming, including URL, URLConnection, Socket, ServerSocket, etc. Java's RMI (Remote Method Activation) mechanism is also an important means of developing distributed applications.

4. The Java language is robust. Java's strong typing mechanism, exception handling, automatic collection of waste, etc. are important guarantees for the robustness of Java programs. Discarding pointers is a smart choice for Java. Java's security checking mechanism makes Java more robust.

5. The Java language is safe. Java is usually used in network environments. For this reason, Java provides a security mechanism to prevent malicious code attacks. In addition to the many security features of the Java language, Java has a security prevention mechanism (class ClassLoader) for classes downloaded through the network, such as allocating different name spaces to prevent replacement of local classes of the same name, byte code inspection, and providing security management Mechanism (class SecurityManager) allows Java applications to set up security sentries.

6. The Java language is architecture neutral. Java programs (files with the suffix java) are compiled into an architecture-neutral bytecode format (files with the suffix class) on the Java platform, and can then be run on any system that implements this Java platform. This approach is suitable for heterogeneous network environments and software distribution.

7. The Java language is portable.

This portability comes from architecture neutrality. In addition, Java also strictly regulates the length of each basic data type. The Java system itself is also highly portable. The Java compiler is implemented in Java, and the Java running environment is implemented in ANSI C.

8. The Java language is interpreted. As mentioned before, Java programs are compiled into bytecode format on the Java platform and can then be run on any system that implements this Java platform. At runtime, the Java interpreter in the Java platform interprets and executes these bytecodes, and the classes required during the execution are loaded into the running environment during the connection phase.

9. Java is high-performance. Compared with those interpreted high-level scripting languages, Java is indeed high-performance. In fact, with the development of JIT (Just-In-Time) compiler technology, Java's running speed is getting closer and closer to C++.

10. The Java language is multi-threaded. In the Java language, a thread is a special object that must be created by the Thread class or its descendants (grandchildren). There are usually two ways to create a thread: first, use the constructor of type Thread(Runnable) to wrap an object that implements the Runnable interface into a thread; second, derive a subclass from the Thread class and override run Method, the object created using this subclass is a thread. It is worth noting that the Thread class has implemented the Runnable interface, so any thread has its run method, and the run method contains the code to be run by the thread. The activity of a thread is controlled by a set of methods. The Java language supports the simultaneous execution of multiple threads and provides a synchronization mechanism between multiple threads (the keyword is synchronized).

11. The Java language is dynamic. One of the design goals of the Java language is to adapt to dynamically changing environments. The classes required by Java programs can be dynamically loaded into the running environment, and the required classes can also be loaded through the network. This also facilitates software upgrades. In addition, classes in Java have a run-time representation and can perform run-time type checking.

The excellent characteristics of the Java language make Java applications extremely robust and reliable, which also reduces the maintenance costs of the application system. Java's comprehensive support for object technology and the API embedded in the Java platform can shorten application system development time and reduce costs. Java's compile-once-run-anywhere nature enables it to provide an open architecture that can be used anywhere and a low-cost way to transfer information between multiple platforms. In particular, Java Enterprise Application Programming Interfaces (Java Enterprise APIs) provide relevant technologies and rich class libraries for enterprise computing and e-commerce application systems.

Related technologies

1. JDBC (Java Database Connectivity) provides a unified interface to connect various relational databases.

2. EJB (Enterprise JavaBeans) allows developers to easily create, deploy and manage cross-platform component-based enterprise applications.

3. Java RMI (Java Remote Method Invocation) is used to develop distributed Java applications. A Java object's methods can be called by a remote Java virtual machine. In this way, remote method activation can occur between peers, or between a client and a server, as long as the applications on both sides are written in Java.

4. Java IDL (Java Interface Definition Language) provides unparalleled interoperability with CORBA (Common Object Request Broker Architecture). This enables Java to integrate heterogeneous business information resources.

5. JNDI (Java Naming and Directory Interface) provides a unified and seamless connection from the Java platform to Java.

This interface blocks the various naming and directory services used by corporate networks.

6. JMAPI (Java Management API) provides a rich set of objects and methods for the development of system, network and service management on heterogeneous networks.

7. JMS (Java Message Service) provides enterprise messaging services, such as reliable message queues, publish and subscribe communications, and all aspects of push/pull technology.

8. JTS (Java transaction Service) provides an open standard for accessing transaction processing resources. These transaction processing resources include transaction processing applications, transaction processing management and monitoring.

In Java technology, it is also worth paying attention to JavaBeans, which is an open standard component architecture that is independent of the platform but uses the Java language. A JavaBean is a Java class that meets the JavaBeans specification and usually defines a real-world thing or concept. The main characteristics of a JavaBean include properties, methods and events. Usually, in a development environment that supports the JavaBeans specification (such as Sun Java Studio and IBM VisualAge for Java), you can visually operate JavaBeans, and you can also use JavaBeans to construct new JavaBeans. The advantage of JavaBeans also lies in the portability brought by Java. Now, EJB (Enterprise JavaBeans) extends the JavaBean concept to the Java server-side component architecture. This model supports multi-tier distributed object applications. In addition to JavaBeans, typical component architectures include DCOM and CORBA. An in-depth discussion of these component architectures is beyond the scope of this book.

Java Open Source Project

Spring Framework Java Open Source J2EE Framework

Spring is a powerful framework that solves many common problems in J2EE development. Spring provides a consistent way to manage business objects and encourages the good habit of programming to interfaces rather than classes. The architectural foundation of Spring is based on the Inversion of Control container using JavaBean properties. However, this is only part of the complete picture: Spring is unique in using IoC containers as a complete solution that focuses on all architectural layers. Spring provides the only data access abstraction, including a simple and efficient JDBC framework, greatly improving efficiency and reducing possible errors. Spring's data access architecture also integrates Hibernate and other O/R mapping solutions. Spring also provides the only transaction management abstraction that can provide a consistent programming model across various underlying transaction management technologies, such as JTA or JDBC transactions. Spring provides an AOP framework written in the standard Java language, which provides declarative transaction management and other enterprise affairs for POJOs - and if you need - you can also implement your own aspects. This framework is powerful enough to enable applications to put aside the complexity of EJB while enjoying the key services associated with traditional EJB. Spring also provides a powerful and flexible MVC Web framework that can be integrated with IoC containers. SpringIDE: an auxiliary development plug-in under the Eclipse platform.

WebWork Java open source Web framework

WebWork is developed by the OpenSymphony organization and is committed to the pull-out MVC model of componentization and code reuse. J2EE web framework. The latest version of WebWork is 2.1. The predecessor of WebWork2.x is WebWork developed by Rickard Oberg, but now WebWork has been split into two projects, Xwork1 and WebWork2.

Xwork is simple, flexible and powerful. It is a standard Command mode implementation and is completely separated from the web layer. Xwork provides many core functions: front-end interceptor, runtime form attribute validation, type conversion, powerful expression language (OGNL – the Object Graph Notation Language), IoC (Inversion of Control inversion control) container, etc. WebWork2 is built on Xwork and handles HTTP responses and requests. WebWork2 uses ServletDispatcher to convert HTTP requests into Action (business layer Action class), session (session) application (application) scope mapping, and request request parameter mapping. WebWork2 supports multi-view representation, and the view part can use JSP, Velocity, FreeMarker, JasperReports, XML, etc. Support for AJAX was added to WebWork2.2, which is built on the two frameworks of DWR and Dojo. EclipseWork: an Eclipse plug-in for WebWork-assisted development

Struts Java open source Web framework

Struts is an MVC framework based on the Sun J2EE platform, which is mainly implemented using Servlet and JSP technologies. Because Struts can fully meet the needs of application development, is easy to use, agile and fast, it has attracted much attention in the past year. Struts integrates Servlets, JSP, custom tags and message resources into a unified framework. When developers use it for development, they no longer need to code themselves to implement a full set of MVC patterns, which greatly saves time, so Struts It is a very good application framework. StrutsIDE: an Eclipse plug-in for Struts-assisted development

Hibernate Java open source persistence layer framework

Hibernate is an open source object-relational mapping framework that very lightly implements JDBC. Large-scale object encapsulation allows Java programmers to use object programming thinking to manipulate the database as they wish. Hibernate can be used in any situation where JDBC is used. It can be used in Java client programs or in Servlet/JSP Web applications. The most revolutionary thing is that Hibernate can replace CMP in the J2EE architecture that uses EJB. , complete the important task of data persistence. Hibernate auxiliary development tools under the Eclipse platform: Hibernate SynchronizerMiddlegenIDE

Quartz Java open source Job scheduling

Quartz is another open source project of the OpenSymphony open source organization in the field of Job scheduling. It can be used with J2EE and J2SE The apps can be combined or used individually. Quartz can be used to create simple or complex daily schedules for running ten, hundreds, or even tens of thousands of Jobs. Jobs can be made into standard Java components or EJBs. The latest version of Quartz is Quartz 1.5.0.

Velocity Java open source template engine

Velocity is a java-based template engine (template engine). It allows anyone to reference objects defined by Java code simply using a template language.

When Velocity is applied to web development, interface designers and Java program developers can simultaneously develop a web site that follows the MVC architecture. That is to say, page designers can only focus on the display effect of the page, while Java program developers focus on the business. Logical encoding. Velocity separates Java code from web pages, which facilitates long-term maintenance of web sites, and also provides us with an alternative to JSP and PHP. Velocity's capabilities extend far beyond web site development. For example, it can generate SQL, PostScript, and XML from templates. It can also be used as a standalone tool to generate source code and reports, or as an integrated component of other systems. use. Velocity can also provide template services for the Turbine web development architecture. Velocity+Turbine provides a template service that allows a web application to be developed in a true MVC model. VeloEclipse: Velocity is an auxiliary development plug-in under the Eclipse platform

IBATIS Java open source persistence layer framework

Using the ORM mechanism provided by ibatis, business logic implementers face many challenges It is a pure Java object. This layer is basically the same as implementing ORM through Hibernate. For specific data operations, Hibernate will automatically generate SQL statements, while ibatis requires developers to write specific SQL statements. Compared with "fully automatic" ORM mechanisms such as Hibernate, ibatis provides greater freedom for system design by compromising the workload of SQL development and database portability. As a useful supplement to "fully automatic" ORM implementation, the emergence of ibatis is of special significance.

Compiere ERP&CRM Java open source ERP and CRM system

Compiere ERP&CRM provides comprehensive solutions for small and medium-sized enterprises around the world, covering everything from customer management, supply chain to financial management fields, supporting international features such as multi-organizations, multi-currencies, multi-accounting models, multi-cost calculations, multi-languages, and multi-tax systems. Easy to install, easy to implement, easy to use. In just a few hours, you can use requisition-purchase-invoice-payment, quotation-order-invoice-collection, product and pricing, asset management, customer relations, supplier relations, employee relations, business performance analysis, etc. Powerful function.

Roller Weblogger Java Open Source Blog

This weblogging design is relatively sophisticated, and the source code is a good learning material. It supports weblogging features such as: comment function, WYSIWYG HTML editing, TrackBack, providing page templates, RSS syndication, blogroll management and providing an XML-RPC interface.

Eclipse Java open source development tool

The Eclipse platform is a development framework donated by IBM to the development source community. It is not famous because of the total amount of funds IBM claims to have invested in development - 40 million. dollars, but because of the results of such a huge investment: a mature, well-designed and scalable architecture.

XPlanner Java Open Source Project Management

XPlanner is a Web-based XP team planning and tracking tool. XP's unique development concepts such as iteration, user stories, etc., XPlanner provides corresponding management tools. XPlanner supports the XP development process and solves problems encountered in developing projects using XP ideas.

XPlanner features include: simple model planning, virtual note cards, tracking of iterations, user stories and work records, automatic iteration of unfinished stories, work time tracking, team efficiency generation, personal work time reports, SOAP interface support .

HSQLDB Java open source DBMS database

HSQLDB (Hypersonic SQL) is a relational database developed purely in Java and provides JDBC driver to access data. Supports ANSI-92 standard SQL syntax. And it takes up very little space. Only about 160K, has a fast database engine.

Liferay Java open source Portal

Represents a complete J2EE application, using technologies such as Web, EJB and JMS. In particular, its front-end interface part uses Struts framework technology and is based on XML. The portlet configuration file can be freely and dynamically expanded, using Web Services to support the acquisition of some remote information, and using Apahce Lucene to implement the full-text search function.

Main features:

1. Provide a single login interface and multiple authentication modes (LDAP or SQL);

2. Administrators can easily manage through the user interface Users, groups, roles;

3. Users can customize personalized portal layout as needed;

4. Can run on mainstream J2EE application servers, such as JBoss+Jetty /Tomcat, JOnAS;

5. Support mainstream databases, such as PostgreSQL, MySQL;

6. Use third-party open source projects, such as Hibernate, Lucene, Struts; < /p>

7. Support multiple languages ??including Chinese;

8. Use the most advanced technologies Java, EJB, JMS, SOAP, XML;

JetSpeed Java Open Source Portal

Jetspeed is an open source Enterprise Information Portal (EIP) implementation using Java and XML. Users can use a browser, mobile phone or other device that supports WAP protocol to access the information portal set up by Jetspeed to obtain information. Jetspeed acts as an information concentrator, gathering information and making it easily available to users.

Jetspeed has the following features:

* Soon to become a standardized Java Portlet API

* Template-based layout, including JSP and Velocity

< p>* Support remote XML content exchange through open content synchronization technology

* Customize the default home page

* Use database for user authentication

* In-memory caching technology , speed up page response

* Support synchronized content through Rich Site Summary technology

* Integrate with Cocoon, WebMacro, Velocity.

* Wireless Markup Language ( WML) support

* Use XML format configuration files to register portlets.

* Complete Web Application Archive (WAR) support

* Web application development Infrastructure

* Can cache remote content locally

* Synchronize with Avantgo

* Portable to all platforms that support JDK1.2 and Servlet 2.2

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* Integrated with Turbine modules and services

* Can generate different personalized services according to different settings of users, installed media types and languages

* Continuous The service allows the portlet to easily store the status of each user, page and portlet

* Using skin technology allows users to select the color and display properties of the portlet

* Customization Features allow administrators to select portlets and define the layout of personal pages

* Store PSML in the database

* Manage users, groups, roles and permissions through Jetspeed's secure portlets

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* Control access to portlets based on roles

JOnAS Java Open Source J2EE Server

JOnAS is an open source J2EE implementation developed in the ObjectWeb Association. Integrate Tomcat or Jetty as its web container to ensure compliance with Servlet 2.3 and JSP 1.2 specifications. JOnAS server relies on or implements the following Java APIs: JCA, JDBC, JTA, JMS, JMX, JNDI, JAAS, JavaMail.

JFox3.0 Java open source J2EE server

JFox is an Open Source Java EE Application Server, dedicated to providing lightweight Java EE application servers. Starting from 3.0, JFox provides a Supports modular MVC framework to simplify the development of EJB and Web applications! If you are looking for a simple, lightweight, efficient, and complete Java EE development platform, then JFox is exactly what you need.

JFox 3.0 has the following features:

1. Redesigned IoC microkernel, incorporating OSGi modular thinking

2. Designed as an embedded architecture, capable of Integrated deployment with any Java Web Server

3. Supports EJB3 and JPA specifications, and supports running EJB and JPA components in two ways, inside and outside the container

4. Supports EJB publishing to the Web Service

5. Adopt JOTM (automatic Form Mapping, Validator, Uploading and other functions, support JSP/Velocity/Freemarker page engine, and support direct injection of EJB in Action

8. Support Multi-application module deployment allows medium and large applications to fully enjoy the advantages of modular development

9. Provides a Manager management module that can view and manage various runtime parameters

10. Provides Petstore application module rewritten based on JFox features

Historical development and characteristics

Introduction to Java

Java is a simple, object-oriented, Distributed, interpreted, robust and safe, structurally neutral, portable, multi-threaded and dynamic language with excellent performance

When SUN launched the Java language in 1995, all The world's attention is attracted by this magical language. So what is so magical about Java?

The Java language was actually born in 1991. It was originally called OAK language and was developed by SUN. A common environment designed for some consumer electronics products. Their original purpose was to develop a platform-independent software technology, and before the emergence of the network, OAK could be said to be unknown, and even almost died. However, the emergence of the network changed. The fate of OAK.

Before the advent of Java, the information content on the Internet was simply boring and rigid HTML documents, which was simply intolerable to those who were obsessed with WEB browsing. After seeing some interactive content in WEN, developers also hope to create a type of application program on the WEB that can be executed without considering the software and hardware platform. Of course, these programs must also have great security guarantees for users. Traditional programming languages ??are incapable of meeting this requirement. The engineers at SUN were keenly aware of this. Starting in 1994, they began to apply OAK technology to the WEB and developed the first version of HotJava as SUN. When the company was officially launched under the name Java in 1995, almost all WEB developers thought: Oh, this is exactly what I want. So Java became a dazzling star, and the ugly duckling suddenly turned into a white swan.

There are different versions of Java development environments, such as Sun's Java Development Kit, referred to as JDK. Later, Microsoft launched the Microsoft Visual J++ Java development environment that supports Java specifications, referred to as VJ++.

Characteristics of Java

1. Platform independence

Platform independence means that Java can run on different platforms. Java introduces the principle of virtual machines and runs on virtual machines to implement Java interfaces on different platforms. Programs written in Java can be shared around the world. Java's data types have nothing to do with machines. The Java Virtual Machine (Java Virtual Machine) is built on hardware and operating systems to implement the interpretation and execution function of Java binary codes and provide interfaces for different platforms.

2. Security

Java programming is similar to C++. Readers who have studied C++ will quickly grasp the essence of Java. Java abandons the direct operation of C++ pointers on memory addresses. When the program is running, the memory is allocated by the operating system, which can prevent viruses from invading the system through pointers. Java provides a security manager for programs to prevent illegal access to programs.

3. Object-oriented

Java absorbs the object-oriented concept of C++, encapsulates data in classes, and uses the advantages of classes to achieve program simplicity and ease of maintenance. The object-related features such as class encapsulation and inheritance allow the program code to be compiled once and then used repeatedly through the above features. Programmers only need to focus on the design and application of classes and interfaces. Java provides numerous general object classes, and you can use the methods of the parent class through inheritance. In Java, the inheritance relationship of a class is single and non-multiple. A subclass has only one parent class, and the parent class of the subclass has another parent class. The inheritance relationship between the Object class and its subclasses provided by Java is like an inverted tree. The root class is the Object class. The Object class is powerful and it and other derived subclasses are often used.

4. Distributed

Java is built on the extended TCP/IP network platform. Library functions provide methods for transmitting and receiving information using HTTP and FTP protocols. This makes it as easy for programmers to work with files on the network as with local files.

5. Robustness

Java is committed to checking program errors during compilation and runtime. Type checking helps catch many errors that occur early in development. Java's own manipulation of memory reduces the possibility of memory errors. Java also implements true arrays, which avoids the possibility of overwriting data. These functional features greatly improve the development cycle of Java applications. And Java also provides Null pointer detection, array boundary detection, exception exit, Byte code verification and other functions.

Java and the C/C++ language

Java provides all the features of a powerful language, but with almost no ambiguity. C++ has poor security, but C and C++ are accepted by everyone, so Java is designed in C++ form to make it easy for everyone to learn.

Java has removed functions such as pointer arithmetic, structures, typedefs, #define, and the need to release memory in the C++ language, reducing 50% of common errors, making Java's language functions very refined. Moreover, because Java is small, the entire interpreter requires only 215K of RAM and adds some very useful features, such as automatic debris collection.

Java implements the basic object-oriented technology of C++ and has some enhancements (some functions have been deleted for the sake of language simplicity). Java processes data in the same way as object data is processed using object interfaces.