Servlets 简明教程

Servlets - Environment Setup

开发环境是您开发 Servlet、测试 Servlet 并最终运行 Servlet 的地方。

A development environment is where you would develop your Servlet, test them and finally run them.

与任何其他 Java 程序一样，您需要使用 Java 编译器 javac 编译 Servlet，在编译 Servlet 应用程序后，将在配置的环境中部署它以进行测试和运行。

Like any other Java program, you need to compile a servlet by using the Java compiler javac and after compilation the servlet application, it would be deployed in a configured environment to test and run..

此开发环境设置涉及以下步骤：

This development environment setup involves the following steps −

Setting up Java Development Kit

此步骤涉及下载 Java 软件开发工具包 (SDK) 的实现并适当地设置 PATH 环境变量。

This step involves downloading an implementation of the Java Software Development Kit (SDK) and setting up PATH environment variable appropriately.

您可从 Oracle 的 Java 网站下载 SDK− Java SE Downloads 。

You can download SDK from Oracle’s Java site − Java SE Downloads.

下载 Java 实现后，请按照给定的说明安装并配置设置。最后设置 PATH 和 JAVA_HOME 环境变量，以引用包含 java 和 javac 的目录，通常是 java_install_dir/bin 和 java_install_dir。

Once you download your Java implementation, follow the given instructions to install and configure the setup. Finally set PATH and JAVA_HOME environment variables to refer to the directory that contains java and javac, typically java_install_dir/bin and java_install_dir respectively.

如果您在 Windows 上运行且将 SDK 安装在 C:\jdk1.8.0_65 中，则需要将以下行放在 C:\autoexec.bat 文件中。

If you are running Windows and installed the SDK in C:\jdk1.8.0_65, you would put the following line in your C:\autoexec.bat file.

set PATH = C:\jdk1.8.0_65\bin;%PATH%
set JAVA_HOME = C:\jdk1.8.0_65

或者，在 Windows NT/2000/XP 上，您还可以右键单击“我的电脑”，选择“属性”，然后选择“高级”，再选择“环境变量”。然后，您需要更新 PATH 值并按“确定”按钮。

Alternatively, on Windows NT/2000/XP, you could also right-click on My Computer, select Properties, then Advanced, then Environment Variables. Then, you would update the PATH value and press the OK button.

在 Unix（Solaris、Linux 等）上，如果 SDK 安装在 /usr/local/jdk1.8.0_65 中并且您使用的是 C shell，則需要将以下内容放入您的 .cshrc 文件中。

On Unix (Solaris, Linux, etc.), if the SDK is installed in /usr/local/jdk1.8.0_65 and you use the C shell, you would put the following into your .cshrc file.

setenv PATH /usr/local/jdk1.8.0_65/bin:$PATH
setenv JAVA_HOME /usr/local/jdk1.8.0_65

或者，如果您使用的是集成开发环境（IDE），例如 Borland JBuilder、Eclipse、IntelliJ IDEA 或 Sun ONE Studio，则编译和运行一个简单程序以确认 IDE 知道您安装 Java 的位置。

Alternatively, if you use an Integrated Development Environment (IDE) like Borland JBuilder, Eclipse, IntelliJ IDEA, or Sun ONE Studio, compile and run a simple program to confirm that the IDE knows where you installed Java.

Setting up Web Server − Tomcat

市场上有很多支持 servlet 的 Web 服务器。一些 Web 服务器可免费下载，Tomcat 就是其中之一。

A number of Web Servers that support servlets are available in the market. Some web servers are freely downloadable and Tomcat is one of them.

Apache Tomcat 是 Java Servlet 和 Java Server Pages 技术的一个开源软件实现，可以充当 servlet 的独立服务器，也可以与 Apache Web 服务器集成。以下是在计算机上设置 Tomcat 的步骤：

Apache Tomcat is an open source software implementation of the Java Servlet and Java Server Pages technologies and can act as a standalone server for testing servlets and can be integrated with the Apache Web Server. Here are the steps to setup Tomcat on your machine −

Download latest version of Tomcat from https://tomcat.apache.org/.
Once you downloaded the installation, unpack the binary distribution into a convenient location. For example in C:\apache-tomcat-8.0.28 on windows, or /usr/local/apache-tomcat-8.0.289 on Linux/Unix and create CATALINA_HOME environment variable pointing to these locations.

可以通过在 Windows 计算机上执行以下命令启动 Tomcat：

Tomcat can be started by executing the following commands on windows machine −

%CATALINA_HOME%\bin\startup.bat
or
C:\apache-tomcat-8.0.28\bin\startup.bat

可以通过在 Unix（Solaris、Linux 等）计算机上执行以下命令启动 Tomcat：

Tomcat can be started by executing the following commands on Unix (Solaris, Linux, etc.) machine −

$CATALINA_HOME/bin/startup.sh
or
/usr/local/apache-tomcat-8.0.28/bin/startup.sh

启动后，可以通过访问 http://localhost:8080/ 获得 Tomcat 附带的默认 Web 应用程序。如果一切正常，则应显示以下结果：

After startup, the default web applications included with Tomcat will be available by visiting http://localhost:8080/. If everything is fine then it should display following result −

有关配置和运行 Tomcat 的更多信息，请参阅此处附带的文档以及 Tomcat 网站：[role="bare"] [role="bare"]http://tomcat.apache.org

Further information about configuring and running Tomcat can be found in the documentation included here, as well as on the Tomcat web site − [role="bare"]http://tomcat.apache.org

可以通过在 Windows 计算机上执行以下命令停止 Tomcat：

Tomcat can be stopped by executing the following commands on windows machine −

C:\apache-tomcat-8.0.28\bin\shutdown

可以通过在 Unix（Solaris、Linux 等）计算机上执行以下命令停止 Tomcat：

Tomcat can be stopped by executing the following commands on Unix (Solaris, Linux, etc.) machine −

/usr/local/apache-tomcat-8.0.28/bin/shutdown.sh

Setting Up the CLASSPATH

由于 servlet 不是 Java Platform, Standard Edition 的一部分，因此必须向编译器标识 servlet 类。

Since servlets are not part of the Java Platform, Standard Edition, you must identify the servlet classes to the compiler.

如果您在 Windows 上运行，则需要将以下行放在 C:\autoexec.bat 文件中。

If you are running Windows, you need to put the following lines in your C:\autoexec.bat file.

set CATALINA = C:\apache-tomcat-8.0.28
set CLASSPATH = %CATALINA%\common\lib\servlet-api.jar;%CLASSPATH%

或者，在 Windows NT/2000/XP 上，您可以转到“我的电脑”→“属性”→“高级”→“环境变量”。然后，您需要更新 CLASSPATH 值并按“确定”按钮。

Alternatively, on Windows NT/2000/XP, you could go to My Computer −> Properties −> Advanced −> Environment Variables. Then, you would update the CLASSPATH value and press the OK button.

在 Unix（Solaris、Linux 等）中，如果您使用 C Shell，则您需要将以下行放入 .cshrc 文件中。

On Unix (Solaris, Linux, etc.), if you are using the C shell, you would put the following lines into your .cshrc file.

setenv CATALINA = /usr/local/apache-tomcat-8.0.28
setenv CLASSPATH $CATALINA/common/lib/servlet-api.jar:$CLASSPATH

NOTE − 假设您的开发目录是 C:\ServletDevel（Windows）或 /usr/ServletDevel（Unix），则您需要以类似于上面添加的方式将这些目录添加到 CLASSPATH 中。

NOTE − Assuming that your development directory is C:\ServletDevel (Windows) or /usr/ServletDevel (Unix) then you would need to add these directories as well in CLASSPATH in similar way as you have added above.