6.3. simple-weather 模块  TOC  6.5. 构建这个多模块项目

6.4. simple-webapp 模块

simple-webapp模块是在simple-parent项目中引用的第二个子模块。这个web项目依赖于simple-weather模块，并且包含了一些用来展示从Yahoo! Weather服务查询到的结果的servlet。

Example 6.4. simple-webapp 模块的 POM

<project xmlns="http://maven.apache.org/POM/4.0.0" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
                      http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.sonatype.mavenbook.ch06</groupId>
    <artifactId>simple-parent</artifactId>
    <version>1.0</version>
  </parent>

  <artifactId>simple-webapp</artifactId>
  <packaging>war</packaging>
  <name>simple-webapp Maven Webapp</name>
  <dependencies>
    <dependency>
      <groupId>org.apache.geronimo.specs</groupId>
      <artifactId>geronimo-servlet_2.4_spec</artifactId>
      <version>1.1.1</version>
    </dependency>
    <dependency>
      <groupId>org.sonatype.mavenbook.ch06</groupId>
      <artifactId>simple-weather</artifactId>
      <version>1.0</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>simple-webapp</finalName>
    <plugins>
      <plugin>
        <groupId>org.mortbay.jetty</groupId>
        <artifactId>maven-jetty-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

simple-weather模块定义了一个十分简单的servlet，它从HTTP请求读取一个邮政编码，调用Example 6.3, “WeatherService 类”中展示的WeatherService，然后将结果打印至HTTP响应的Writer。

Example 6.5. simple-webapp 的 WeatherServlet

package org.sonatype.mavenbook.web;

import org.sonatype.mavenbook.weather.WeatherService;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class WeatherServlet extends HttpServlet {
    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
        throws ServletException, IOException {
        String zip = request.getParameter("zip" );
        WeatherService weatherService = new WeatherService();
        PrintWriter out = response.getWriter();
        try {
            out.println( weatherService.retrieveForecast( zip ) );
        } catch( Exception e ) {
            out.println( "Error Retrieving Forecast: " + e.getMessage() );
        }
        out.flush();
        out.close();
    }
}

在WeatherServlet中，我们初始化了一个在simple-weather中定义的WeatherService类的实例。在请求参数中提供的邮政编码被传给retrieveForecast()方法，并且返回结果被打印至HTTP响应的Writer。

最后，src/main/webapp/WEB-INF目录下的web.xml将所有这一切绑在一起。web.xml中的servlet和servlet-mapping元素将路径/weather匹配至WeatherServlet。

Example 6.6. simple-webapp 的 web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>simple</servlet-name>
    <servlet-class>org.sonatype.mavenbook.web.SimpleServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>weather</servlet-name>
    <servlet-class>org.sonatype.mavenbook.web.WeatherServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>simple</servlet-name>
    <url-pattern>/simple</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>weather</servlet-name>
    <url-pattern>/weather</url-pattern>
  </servlet-mapping>
</web-app>

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