【Java项目脚手架系列】第二篇：JavaWeb项目脚手架

【Java项目脚手架系列】第二篇：JavaWeb项目脚手架

前言

在Java Web开发中，一个好的项目脚手架可以大大提高开发效率，减少重复工作。本篇文章将介绍一个基于Maven的JavaWeb项目脚手架，它包含了基础的Web开发配置和常用功能。

什么是JavaWeb项目脚手架？

JavaWeb项目脚手架是一个基于Maven的Web项目模板，它提供了：

1. 标准的Web项目结构
2. 基础的Web开发配置
3. 常用功能组件
4. 最佳实践示例

JavaWeb项目脚手架

1. 项目结构

javaweb-scaffold/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/
│   │   │       └── example/
│   │   │           ├── filter/
│   │   │           │   └── CharacterEncodingFilter.java
│   │   │           └── servlet/
│   │   │               ├── Error404Servlet.java
│   │   │               ├── Error500Servlet.java
│   │   │               └── HelloServlet.java
│   │   ├── resources/
│   │   │   └── log4j2.xml
│   │   └── webapp/
│   │       ├── WEB-INF/
│   │       │   └── web.xml
│   │       ├── error/
│   │       │   ├── 404.jsp
│   │       │   └── 500.jsp
│   │       └── index.jsp
│   └── test/
│       ├── java/
│       │   └── com/
│       │       └── example/
│       │           └── servlet/
│       │               └── HelloServletTest.java
│       └── resources/
├── docs/
│   └── 02-javaweb-scaffold.md
├── pom.xml
└── README.md

2. 核心文件内容

2.1 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.example</groupId><artifactId>javaweb-scaffold</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target><servlet.version>4.0.1</servlet.version><jsp.version>2.3.3</jsp.version><jstl.version>1.2</jstl.version><junit.version>5.8.2</junit.version><mockito.version>4.5.1</mockito.version><lombok.version>1.18.24</lombok.version><log4j2.version>2.17.2</log4j2.version></properties><dependencies><!-- Servlet API --><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>${servlet.version}</version><scope>provided</scope></dependency><!-- JSP API --><dependency><groupId>javax.servlet.jsp</groupId><artifactId>javax.servlet.jsp-api</artifactId><version>${jsp.version}</version><scope>provided</scope></dependency><!-- JSTL --><dependency><groupId>javax.servlet</groupId><artifactId>jstl</artifactId><version>${jstl.version}</version><scope>compile</scope></dependency><!-- JUnit 5 --><dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter-api</artifactId><version>${junit.version}</version><scope>test</scope></dependency><dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter-engine</artifactId><version>${junit.version}</version><scope>test</scope></dependency><!-- Mockito --><dependency><groupId>org.mockito</groupId><artifactId>mockito-core</artifactId><version>${mockito.version}</version><scope>test</scope></dependency><!-- Lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version><scope>provided</scope></dependency><!-- Log4j2 --><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-api</artifactId><version>${log4j2.version}</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-core</artifactId><version>${log4j2.version}</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-slf4j-impl</artifactId><version>${log4j2.version}</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>${maven.compiler.source}</source><target>${maven.compiler.target}</target></configuration></plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-war-plugin</artifactId><version>3.3.2</version></plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-surefire-plugin</artifactId><version>2.22.2</version></plugin><plugin><groupId>org.apache.tomcat.maven</groupId><artifactId>tomcat7-maven-plugin</artifactId><version>2.2</version><configuration><port>8080</port><path>/javaweb-scaffold</path></configuration></plugin></plugins></build>
</project>

2.2 web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaeehttp://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"version="4.0"><display-name>JavaWeb Scaffold</display-name><!-- 字符编码过滤器 --><filter><filter-name>characterEncodingFilter</filter-name><filter-class>com.example.filter.CharacterEncodingFilter</filter-class><init-param><param-name>encoding</param-name><param-value>UTF-8</param-value></init-param></filter><filter-mapping><filter-name>characterEncodingFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping><!-- 错误页面配置 --><error-page><error-code>404</error-code><location>/error/404.jsp</location></error-page><error-page><error-code>500</error-code><location>/error/500.jsp</location></error-page>
</web-app>

2.3 CharacterEncodingFilter.java

package com.example.filter;import javax.servlet.*;
import java.io.IOException;public class CharacterEncodingFilter implements Filter {private String encoding;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {encoding = filterConfig.getInitParameter("encoding");if (encoding == null) {encoding = "UTF-8";}}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {request.setCharacterEncoding(encoding);response.setCharacterEncoding(encoding);chain.doFilter(request, response);}@Overridepublic void destroy() {}
}

2.4 HelloServlet.java

package com.example.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/hello")
public class HelloServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");response.getWriter().write("Hello from JavaWeb Scaffold!");}
}

2.5 Error404Servlet.java

package com.example.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/error/404")
public class Error404Servlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");request.getRequestDispatcher("/error/404.jsp").forward(request, response);}
}

2.6 Error500Servlet.java

package com.example.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/error/500")
public class Error500Servlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");request.getRequestDispatcher("/error/500.jsp").forward(request, response);}
}

2.7 index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head><meta charset="UTF-8"><title>JavaWeb Scaffold</title>
</head>
<body><div class="container"><h1>Welcome to JavaWeb Scaffold</h1><p>Click <a href="hello">here</a> to test the HelloServlet.</p></div>
</body>
</html>

2.8 log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN"><Properties><Property name="LOG_PATTERN">%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</Property><Property name="APP_LOG_ROOT">logs</Property></Properties><Appenders><Console name="Console" target="SYSTEM_OUT"><PatternLayout pattern="${LOG_PATTERN}"/></Console><RollingFile name="FileAppender" fileName="${APP_LOG_ROOT}/app.log"filePattern="${APP_LOG_ROOT}/app-%d{yyyy-MM-dd}-%i.log"><PatternLayout pattern="${LOG_PATTERN}"/><Policies><TimeBasedTriggeringPolicy interval="1"/><SizeBasedTriggeringPolicy size="10MB"/></Policies><DefaultRolloverStrategy max="10"/></RollingFile></Appenders><Loggers><Root level="info"><AppenderRef ref="Console"/><AppenderRef ref="FileAppender"/></Root></Loggers>
</Configuration>

2.9 404.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head><meta charset="UTF-8"><title>404 - Page Not Found</title><style>.error-container {text-align: center;margin-top: 100px;}.error-code {font-size: 72px;color: #e74c3c;}.error-message {font-size: 24px;margin: 20px 0;}.home-link {color: #3498db;text-decoration: none;}</style>
</head>
<body><div class="error-container"><div class="error-code">404</div><div class="error-message">Oops! The page you're looking for doesn't exist.</div><a href="${pageContext.request.contextPath}/" class="home-link">Return to Home</a></div>
</body>
</html>

2.10 500.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head><meta charset="UTF-8"><title>500 - Internal Server Error</title><style>.error-container {text-align: center;margin-top: 100px;}.error-code {font-size: 72px;color: #e74c3c;}.error-message {font-size: 24px;margin: 20px 0;}.error-details {color: #7f8c8d;margin: 20px 0;}.home-link {color: #3498db;text-decoration: none;}</style>
</head>
<body><div class="error-container"><div class="error-code">500</div><div class="error-message">Internal Server Error</div><div class="error-details">An unexpected error occurred. Please try again later.</div><a href="${pageContext.request.contextPath}/" class="home-link">Return to Home</a></div>
</body>
</html>

2.11 HelloServletTest.java

package com.example.servlet;import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
import java.io.StringWriter;import static org.mockito.Mockito.*;class HelloServletTest {@Mockprivate HttpServletRequest request;@Mockprivate HttpServletResponse response;private HelloServlet servlet;private StringWriter stringWriter;private PrintWriter writer;@BeforeEachvoid setUp() throws Exception {MockitoAnnotations.openMocks(this);servlet = new HelloServlet();stringWriter = new StringWriter();writer = new PrintWriter(stringWriter);when(response.getWriter()).thenReturn(writer);}@Testvoid doGet_ShouldWriteHelloMessage() throws Exception {// Whenservlet.doGet(request, response);// Thenverify(response).setContentType("text/html;charset=UTF-8");writer.flush();assertTrue(stringWriter.toString().contains("Hello from JavaWeb Scaffold!"));}
}

3. 使用说明

1. 环境准备

   • JDK 8+
   • Maven 3.6+
   • Tomcat 8.5+

2. 克隆项目

   git clone git@gitee.com:zengqiang_wang/leecode-inteview-questions-journal.git
   

3. 导入IDE

   • 推荐使用IntelliJ IDEA
   • 选择"Open as Maven Project"

4. 运行项目

   mvn tomcat7:run
   

   访问：http://localhost:8080/javaweb-scaffold/

4. 最佳实践

1. 项目结构

   • 遵循标准的Web项目结构
   • 合理划分包层次
   • 保持代码整洁

2. 编码规范

   • 统一使用UTF-8编码
   • 使用字符编码过滤器
   • 规范JSP页面编码

3. 错误处理

   • 配置统一的错误页面
   • 记录详细的错误日志
   • 提供友好的错误提示

4. 测试编写

   • 使用JUnit 5编写单元测试
   • 使用Mockito模拟Servlet环境
   • 测试覆盖核心功能

5. 常见问题

1. IDEA社区版无Tomcat插件

   • 使用Maven插件运行
   • 安装Smart Tomcat插件
   • 配置Tomcat服务器

2. 首页500错误

   • 检查JSTL依赖配置
   • 简化JSP页面内容
   • 配置错误页面

3. 编码问题

   • 确保所有文件使用UTF-8编码
   • 配置字符编码过滤器
   • 检查JSP页面编码声明

6. 总结

这个JavaWeb项目脚手架提供了一个基础的Web开发环境，包含了常用的配置和功能。通过解决常见问题，我们可以快速搭建一个可用的Web项目。

7. 下期预告

下一期我们将介绍SpringMVC项目脚手架，它将基于本期项目进行扩展，添加Spring MVC相关功能，包括：

• 标准的MVC架构
• 统一响应处理
• 统一异常处理
• 参数校验
• 文件上传
• RESTful API支持

敬请期待！