From: http://www.matrix.org.cn/Article/808.html
The initiator asked, for example,: "How to configure environment variables" "How to run servlet"? This kind of problem is too much. Now I will write a beginner entry to read, so that I will have a guiding role in beginners! The first is the download tool: I suggest that beginners use EditPlus JDK, I think if I use, for example, JB, Eclipse, JCREATOR, although it is convenient to start, but even how to configure environment variables, it is difficult to achieve it. Know the point of it. You can download: editplus (the latest version is V2.11): http://count.skycn.com/softdown.php? Id = 3641 & url = http: //sc-http.skycn.net/down/EPP211A_CN. EXE JDK (the latest version is java2sdk1_4_2): http://count.skycn.com/softdown.php? id = 3116 & url = http: //sc-http.skycn.net/down/j2sdk-1_4_2-windows-i586.exe (This is for windows) then installing JDK, I put it below the C: / JDK directory. Then set the problem with ClassPath: Java running environment, which is just like the operating system to search for the executable, even the simple programs that HelloWorld will be traversed, and JVM will also traverse each path defined by classpath. Find the corresponding file. I believe that the system used is not 2K is XP, then set the path: My Computer -> Properties -> Advanced -> Environment Variables and add: C: / JDK / Bin ;; / JDK / lib can also be configured such: C: / JDK / BIN;; C: /JDK/LIB/dt.jar; c: /jdk/lib/tools.jar ★ Remember: Environment variables. Remember Less, it represents the current path, if there is less error, etc.! Dt.jar is a class library about running the environment. Tools.jar is about the class library for some tools. If there is no configuration: C: / JDK / BIN, "Javac 'is not internal or external command, nor is it runable Or batch files. "This error. Below we will write an example program: Open EditPlus, create a new Java file, please use the following input, you will not miss it, and select the case: public class helloworld {public static void main (string [] args) {system. Out.println ("Hello, World!");}} then save this file (Ctrl S) to HelloWorld.java, Java is sized, so case sensation must be divided, is helloworld.java is not HelloWorld. Java or other.
Run: Start -> Run -> CMD Switch to the current directory in the console: Javac HelloWorld.javajava HelloWorld You will see the output of Hello, World! Javac is compiled in the console, which compiles helloWorld.java HelloWorld.class Java is an explanation command, and JVM explains the HelloWorld.class. At this time: 1, if Exception in thread "main" java.lang.noclassdeffounderror: HelloWorld is that you didn't add that in the environment variable. ( DOT) 2, if Exception in Thread "Main" java.lang.nosuchmethoder: main or helloWorld.java: main or helloworld.java: 1: public class helloworld must be defined in a file caled "HelloWorld.java". That is, you didn't know the case. Write this HelloWorld or save it to helloworld.java. This name must be said to the question of the environment variable as the name of the public class, let's talk about how to compile and run in Editplus, in the Tools-> Parameter Setting -> Configuring User Tools 1. Add Tools (Add Application) Menu Text: Compile Java Program Program: C: /jdk/bin/javac.exe Parameters: File Name Initial Directory: File Directory 2. Add Tool (Add Application) Menu Text: Run Java Program Program: C: / JDK / BIN / Java.exe Parameters: File Name (excluding extensions) Initial directory: File Directory Tools Group Names can be added, such as Debug Java Program. Then in the Tools drop-down menu, you will see two options of Compile Java Program and Run Java Program, you can use Ctrl 1 compile and Ctrl 2 running the program. Let's discuss the running environment of servlet: Run servlet , JSP / Servlet Container, I suggest that beginners use Tomcat. Tomcat (Latest Version 5.0): http://cvs.apache.org/builds/jakarta-tomcat-5/nightly/jakarta-tomcat-5-bin-20030725.z then extract this compression package to: C: / Tomcat Then configure environment variables; add three system variables: java_home: c: / jdktomcat_home: c: / tomcatclasspath:% java_home% / lib;% Tomcat_Home% / lib tomcat is configured, the following checks whether Tomcat can run : Go to the C: / Tomcat / bin in the console, run Startup, and then appear on a window, and jump a big string, and finally the server has run. Enter http: // localhost: 8080 in the browser, the welcome interface, indicating that Tomcat is no problem.
Then write your first servlet as above, write your first servlet.
import java.io *;. import javax.servlet *;. import javax.servlet.http *;. public class HelloWorld extends HttpServlet {public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType ( "text / html "); PrintWriter out = response.getwriter (); out.println ("
); Out.Println ("this is my first servlet"; out.println ("< / title> </ head> <body> "); Out.println (" <H1> Hello, World! </ H1> "); Out.Println (" </ Body> </ HTML> ");}} Then use Javac HelloWorld.java to compile this file, if there is an import javax.servlet. * So you should copy the servlet.jar file inside C: / Tomcat / Common / Lib to C: / JDK / JRE / LIB / Ext, compiled again, there is no problem! Then in the C: / Tomcat / WebApps / root inside the Tomcat directory: root / index.htmlroot / welcom.jsproot / web-inf / lib / myservlet.jar (if your servlet is .class The .jar file is placed under LIB) Root / Web-INF / CLASS / HELLOWORLD.CLASS (put the helloWorld.class file generated above) and enter http: // localhost: 8080 / Servlet / HelloWorld, who is returned by Server's expectations: Error 404 - NOT FOUND What is going on? Servlet must use the web.xml file under the directory of C: / Tomcat / WebApps / root / web -in, open this web.xml file with EP, add: <servlet> <servlet-name> HelloWorld </ Servlet-name> <servlet-class> HelloWorld </ servlet-class> </ servlet> <servlet-maping> <servlet-name> HelloWorld </ servlet-name> <url-pattern> / servlet / helloworld </ url- Pattern> </ servlet-mapping> Structure <servlet> <servlet-name></p></div><div class="text-center mt-3 text-grey">
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