JDK, Java EE, J2SE, J2ME four confusing concepts differentiate _java

What is the conceptual difference between jdk,j2ee,j2se,j2me?

1. What are these?

The JDK is the Java Development Toolkit, the equivalent of a Java library function, a toolkit for compiling and running Java programs.

Java 2 Enterprise Edition is Java, an Enterprise Edition for enterprise-Class application service development

J2SE is Java 2 Standard Edition is a standard version of Java for standard application development

J2ME is Java 2 Micro Edition is a miniature version of Java, often used in mobile phone development

J2ee,j2se,j2me is Java for different uses to provide different services, that is, to provide different types of class libraries.

Java 2 Enterprise Edition for enterprise network applications, J2SE for common PC applications (Java 2 Standard Edition), and

J2ME (Java 2 Micro Edition) Three versions for embedded devices and consumer electronics

For beginners, they start with J2SE.

2. The difference between Java EE and J2SE:

Java EE is based on the J2SE to add a series of enterprise application programming interface. Java EE contains a lot of technology! There are the JSP you are familiar with,

SERVLET,JDBC,JME etc 13 Technology!

Java EE is mainly used to do b/s structure of the application! That is, based on browsers and servers!

J2se give me the feeling that only need one container is enough, Java EE support distributed components can exist multiple containers at the same time

1), what exactly is the Java EE?

Java EE, is a standard proposed by Sun, the product conforms to this standard is called "implementation"; One of the Sun's Java EE development packages you download is a

Such "Implementation", and Jboss,weblogic,websphere is an "implementation" of the Java EE standard. Because of Jboss,weblogic,

WebSphere itself has the Java EE API, so it can be implemented without Sun Java EE.

2), Java-EE SDK and J2sdkee difference

In fact, you can take the Java EE SDK and J2sdkee as one thing, officially called the Java EE SDK. But if you scrutinize it, you can use the following

method to understand: J2eesdk is the JDK, this is the development EJG must be installed, J2sdkee is the Java development environment, this is to install, in fact, if

You installed JBoss, you do not have to install all the J2sdkee, as long as one of the files named Java-ee copy the past can be, that is to say

JDK must be installed, and J2sdkee do not need to see what you use to make containers.

3, installed in the Java EE SDK also need to install J2SE SDK?

When downloading j2ee1.4 on the Sun's web site, there are two download packages:

One is the j2ee1.4 SDK complete package (all in one), including Java EE server,j2se, sample, API Doc; The Java EE seems to contain j2se almost

There's something. I think the Java EE also has a JDK, which is the same as the lib below the J2SE (same version). But the JRE is not as big as the Java EE than

J2SE a lot more, such as java.servlet.*, java.servlet.http.* and so on.

The Java EE is lets you use to develop the Java EE specification the thing. If it is for the Web server, not to install the Java EE also line, just install a JRE (even

J2SE, plus a servlet engine (such as Tomcat) is enough.

Look at the following, at a glance:

J2SE = = JDK = = Bin + demo + include + JRE + lib + src.rar//sun official JDK1.4.2

Java EE = = jdk + ...//the JDK here is not as big as the JRE file above, for the reasons stated above.

The other is a separate Java EE server, which requires the installation of the J2SE SDK before installation.

No matter which, after the installation completes, must set the JAVA_HOME,J2EE_HOME,CLASSPATH environment variable, then runs the Java EE server to be able.

For the convenience of developers, Sun distinguishes Java as J2SE (Java 2 Standard Edition), Java 2 Enterprise Edition, J2ME (Java 2 Micro Edition), and Java Card four kinds of platforms. J2SE is the foundation of all Java technologies, and no matter what platform Java Applications developers are developing, they must first learn from J2SE. Java EE technology is focused on the application of enterprise Server side. J2ME mainly for embedded systems, including mobile phones, PDAs and so on. Sun also offers free J2ME Wireless Toolkit for the development of mobile apps. Java card technology is used to develop applications that can be implanted into IC smart cards.

The software development kits for the above four platforms (Software Development KIT,SDK) are free and can be downloaded from Sun's website. Of course, using only the SDK is too much of a stress, we need to develop tools to improve development efficiency. Such tools are called integrated development environments (integrated Development environment,ide). In the past, the two Ides of Borland JBuilder and IBM eclipse were most favored by Java programmers, while Sun's own Ides were obscure. After 2004, Sun placed its IDE in an important position to push for the development of NetBeans and Java studio. The former is an open source tool that is written entirely in Java, while the latter is a heavyweight official development tool. Sun's development tools are the root of the red, Java programmers can finally Bath Sun (Sun) Shine!

The relationship and difference between JDK, Java EE, J2SE, J2ME to introduce you here, is not so confusing, I hope that you understand the JDK, Java, J2SE, J2ME between the concept of help.