Servlet / JSP Configuration Getting Started Selection Since Fanyamin's Blog's BLOG, "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. It is known to 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 (I will find it yourself by the registration code, there are many online) 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 am installing it from the C: / JDK directory: then is the problem with classpath Just as the operating system uses PATH to search for executables, the Java runtime also traversed ClassPath to find classes, even if the HelloWorld is simple, JVM will also traverse each path defined by classpath until the corresponding file is found. . 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 cannot 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.
Then you will write the program below: First is (HelloWorld.java), open EditPlus, create a new Java file, please enter the following input, you want a word unlike, 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, remember the case must be divided, is helloworld.java is not HelloWorld.java or other below, start -> Run -> CMD Switch to the current directory in the console: Javac HelloWorld.javajava HelloWorld You will see the output of Hello, World! (no Come out? I take the computer :)) Javac is the compile command, which compiles helloWorld.java to HelloWorld.classjava is the explanation command, and JVM explains the HelloWorld.class. At this time: 1. If Exception in Thread "Main" java.lang.noclassdefounderror: HelloWorld is that you didn't add that in the environment variable. (Dot) 2.
If an Exception in Thread "Main" java.lang.nosuchmethoder: main or helloWorld.java: main or helloworld.java: PUBLIC CLAS HELLOWORLD MUST BE Defined in a file caled "HelloWorld.java". That is, you didn't have a case write to this HelloWorld Or keep it as helloWorld.java this name must be said to the environment variable as the name of the public class, let me first say how to compile and run in EditPlus, set in Tools-> parameter settings -> Configuring User Tools 1. Add Tools (Add Apps) Menu Words: Compile Java Program Programs: C: /JDK/bin/javac.exe Parameters: File Name Initial Directory: File Directory 2. Add Tool (Add App) Menu text: Run Java Program program: c: /jdk/bin/java.exe parameter: file name (excluding extension) Initial directory: File Directory Tool Group Name You can add, such as Debug Java Program then dropped in Tools drop-down menu You will see two options for Compile Java Program and Run Java Program, you can use Ctrl 1 compile and Ctrl 2 running the program to discuss the run of the servlet: First, you need to run the servlet, you need JSP / servlet Container, I suggest that beginners use Tomcattomcat (latest version 5.0): http://cvs.apache.org/builds/jakarta-tomcat-5-bin-20030725.zip then put this compression package Unzipped to: c: / tomcat and then configure environment variables: Add three system variables: java_home: c: / jdktomcat_home: c: / tomcatclasspath:% java_home% / lib;% Tomcat_Home% / libtomcat environment variable is configured, The following checks whether Tomcat is able to run: Go to the C: / Tomcat / bin in the console, run the startup, then there is a window, and jump a big string, and finally the server has run in the browser. HTTP: // LO Calhost: 8080, the welcome interface, it means that tomcat has no problem then, written to your first servletimport 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 ( "
</p>
<p>"); 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 it should be C: / The servlet.jar file in Tomcat / Common / Lib is copied to C: / JDK / JRE / LIB / EXT, and it is compiled again. It is no problem! Then in the C: / Tomcat / WebApps / root inside the tomcat directory as follows File Structure: root / index.html root / welcom.jsp root / web-inf / lib / myservlet.jar (if your servlet is piloted. JAR file, put it under LIB) Root / Web- INF / CLASS / HELLOWORLD.CLASS (put the helloworld.class files generated above) and enter http: // localhost: 8080 / servlet / helloWorld: 8080 / servlet / helloworld: Error 404 - NOT FOUND What is going on? Servlet must use the web.xml file below this directory below, 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-maping> Structure <s ERVLET> <servlet-name> HelloWorld </ servlet-name> <servlet-class> helloworld </ servlet-class> </ servlet> represents the included servlet class. The following structure <servlet-mapping> <servlet-name > HelloWorld </ servlet-name> <url-pattern> / servlet / helloworld </ url-pattern> </ servlet-maping> indicates which URL schema that specifies the Helloservlet to map.</p>
<p>After modifying web.xml, restart Server, then enter http: // localhost: 8080 / servlet / helloWorld, then a Hello, World! Waiting for you, congratulations, you are flattening :) Ai, hands play Tired, write here, I hope to have a little role in beginners! ============================================================================================================================================================================================================= ========================= How to build a connection database app? For example, connect Access, and SQL Sever. I heard that there is a JDBC JDBC-ODBC bridge.</p>
<p>At present, only JDK1.4 on my machine, what environment I want to use with JDBC? If you want a JDBC driver, you can go down? And how do you write? -------------------------------------------------- ------------- If you use the drive bridge, you don't need another installation. Don't install anything in the control, the bridge -> Management Tools -> Data Source (ODBC) -> SystemDSN Add you Database mapping, select the corresponding database driver and then connect the database through the JDBC: ODBC: set the DSN name --------------------- ------------------------------------------ package cbk00d.common; / ** * Title: * Description: * Copyright: Copyright (c) 2001 * Company: * @Author * @version 1.0 * / import java.io. *; import java.util. *; Import java.sql. *; Import java. lang *;. public class DBConnect {private String jdbcDriver = null; private String jdbcURL = null; private String userName = null; private String password = null; public DBConnect () {jdbcDriver = "sun.jdbc.odbc.JdbcOdbcDriver"; jdbcURL = "JDBC: ODBC: CBK"; username = "system"; password = "manager";} public connection getConnec tion () {Connection connection = null; try {Class.forName (jdbcDriver); connection = DriverManager.getConnection (jdbcURL, userName, password);} catch (Exception e) {System.out.println (e);} return connection This is an ordinary connection method! Just modify it.</p>
<p>-------------------------------------------------- ------------- It seems like this, must be rs.next () JDBC-ODBC bridge is not good? ^ _ ^ Java connection database There are a variety of ways: according to the different database drivers required, divided into four: 1: 1 type driver. This is the way the JDBC-ODBC bridge. But this method is not suitable for reuse and maintenance of the program, not recommended. A database of ODBC drivers are required. 2: 2 type driver. This is the form of the JDBC manufacturer API. Vendor API usually uses C, so this approach is not long. 3: 3 type driver. This is the form of JDBC vendor Database Connection Server Database. This method is to have a server that is dedicated to database connections between Java and Database (generally provided by database vendors). His benefits are to optimize the connection. 4: Category 4 driver. This is the connection method of pure JDBC Database. It is also recommended to connect. This makes Application to the database, developers only need to care about internal logic without paying attention to specific implementations of database connections. There are two ways to connect in this: hard-coding mode is the necessary parameters that are hardly encapsulated in the database. JNDI DataSource method. That is to set a DataSource source in the outline environment of the program, there is a JNDI name, and the program only needs to find this name to get a database connection object.</p></div><div class="text-center mt-3 text-grey">
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