I. JDK (Java Development Kit) JDK is the core of Java, including Java Runtime Envir, a bunch of Java Tools, and Java-based libraries (RT.jar). Regardless of the Java application server, it is built into a version of JDK. So master JDK is the first step in learning Java. The mainstream JDK is the JDK released by Sun. In addition to Sun, many companies and organizations have developed their JDK, such as the JDKTed by IBM, BEA's JROCKET, as well as GNU organizations, etc. . The JVM (Java Virtual Machine) of the IBM's JDK is much higher than the JVM contained in Sun JDK. Jrockets running in the X86 platform are also much better than Sun JDK in the X86 platform. But no matter what, we still need to master Sun JDK first.
1, JDK download and installation JDK is also known as J2SE (Java2 SDK Standard Edition), you can download from Sun's Java website,
http://java.sun.com/j2se/downloads.html, JDK current version is J2SDK1.4.2, it is recommended to download the version of JDK, download page here:
Http://java.sun.com/j2se/1.4.2/download.html. Downloading JDK is an executable installer, the default installation will be installed in the C: / Program files / java / directory, install a set under C: /J2SDK1.4.2 JDK (also included a set of JRE). Then we need to increase Java path C: /J2SDK1.4.2/bin at the forefront of the environment variable Path. This way, JDK is installed.
2, JDK command tool JDK's most important command line tool: Java: Start JVM execution Class Javac: Java compiler JAR: Java package tool Javadoc: Java document generator These command lines must be very familiar, for each parameter It is very proficient. For these commands, there is a detailed documentation on the JDK Documentation.
Second, JDK Documentation Documentation also has downloaded connections in JDK's download page, it is recommended to download the documentation at the same time. Documentation is the most important programming manual covers the description of all Java all aspects. It can be said that learning Java programming, most of the time is watching this documentation. I am carrying it with you, when I write Java code, I will see it at any time.
Third, the App Server App Server is a platform that runs Java Enterprise Components, which constitutes the main operating environment of the application. The current mainstream App Server is a WebLogic Server and IBM's WebSphere and free JBOS, and one of them can be learned. Personally recommend WebLogic, because it is more convenient, developed and deployed, is Java Enterprise software developers preferred development platform. Believe in a brief introduction to several common App Server:
1, Tomcat Tomcat is not a real app server, it is just a web container that can support running Server / JSP, but Tomcat also expands some app server features, such as JNDI, database connection pool, user transaction, etc. Wait. Tomcat is very widely used in small and medium-sized Java web applications, so this article does a little download, install, and configure Tomcat: Tomcat is a sub-project under the Jakarta project under Apache, its main website is: http: / /jakarta.apache.org/tomcat/, Tomcat latest version is Tomcat4.1.27, software download connection is:
http://www.apache.org/dist/jakarta/tomcat-4/binaries/. Download Tomcat can download the ZIP package directly, you can also download the EXE installation package (personal suggestion zip cleaner), no matter which case, after downloading (ZIP direct decompression). Need to set two environment variables: java_home = c: /j2sdk1.4.2 Catalina_Home = D: / tomcat4 (your Tomcat installation directory) This is installed, start Tomcat Run Catalina_Home / Bin / Startup.bat, close Tomcat Run Shutdown. BAT script. After Tomcat starts, use the 8080 port by default, so you can use your browser to access
Http: // localhost: 8080 Tests whether Tomcat is started normally. Tomcat provides two management tools for two web interfaces, and the URLs are:
Http: // localhost: 8080 / admin / index.jsp.jsp
Http: // localhost: 8080 / manager / html Before enabling these two management tools, you need to manually configure the administrator user and password. Use a text tool to open Catalina_Home / conf / tomcat-user.xml, add the following line:
2, Bea WebLogic WebLogic can be downloaded to the latest WebLogic8.1 Enterprise version after free to the BEA website, license can be used for free for free, in fact, this is fully enough. WebLogic download connection:
http://commerce.be.com/index.jsp, ./EDOCS.BEA.com/.
3, IBM WebShpere WebSphere can also be downloaded to a free trial version, to the IBM's DeveloperWorks website, you can see download and related WebSphere's data for WebSphere trial products, the connection of WebSphere, the developerWorks Chinese website is:
Http://www-900.ibm.com/developerWorks/cn/wsdd/, WebSphere download: http://www7b.software.ibm.com/wsdd/...Wassupport.html.
4, JBoss JBoss is a free open source App Server, you can download from JBoss website for free:
Http://www.jboss.org/index.html, but ... n.com/idea.html
Fourth, Java Applied Running Environment Java Application Simply divides the following aspects:
1. Java's desktop application desktop applications generally only need JRE support is enough.
2, Java Web Application Java's web application requires at least JDK and a web container (such as Tomcat), and a multi-user database, the web application is divided into three layers: browser layer: browser display User page Web layer: Run servlet / JSP DB layer: backend database provides data access services to Java programs
3, Java enterprise application enterprise application is more complicated, can be extended to N layers, the simplest situation will be divided into 4 layers: browser layer: browser displays User page Client layer: Java client graphics (or program) Directly and Web Layers or EJB Layer Interaction Web: Run Servlet / JSP EJB layer: Run EJB, complete business logic operation DB layers: backend database, provide data access services to Java programs
4, Java embedded application Java embedded application is a field of unhappy, engaged in embedded development, need to download J2ME development kits from Sun, J2ME contains embedded device-specific virtual machine KVM, and the JVM included in ordinary JDK different. It also needs to download the simulator to a specific embedded vendor.
