# mini-tomcat

**Repository Path**: linestyle007/mini-tomcat

## Basic Information

- **Project Name**: mini-tomcat
- **Description**: mini-tomcat
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 1
- **Forks**: 0
- **Created**: 2021-05-16
- **Last Updated**: 2024-01-01

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

## 准备工作

### 流程架构图

![mini-tomcat](mini-tomcat.png)

* 解析配置
  * **加载外部class文件工具类** => 加载 webapps/*/web.xml中的sevlet类
  * 解析web.xml => 将servlet类加载到uri2servlet中
  * 初始化线程池  => 解决socket client请求超时假死时，其它客户端能正常响应
* 提供socket通信服务
* 请求request对象
* 请求资源
* 响应response对象

### 配置文件

#### server.xml

```xml
<?xml version="1.0" encoding="UTF-8" ?>
<Server>
    <Service>
        <Connector port="8080"/>
        <Engine>
            <Host name="127.0.0.1" appBase="/Users/xw/Documents/webapps"></Host>
        </Engine>
    </Service>
</Server>
```

#### web.xml

> 说明：每个部署应用的配置文件
>
> 位置：{appBase}/{appName}/web.xml

```xml
<web-app>
    <servlet>
        <servlet-name>userServlet</servlet-name>
        <servlet-class>server.UserServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>userServlet</servlet-name>
        <url-pattern>/user</url-pattern>
    </servlet-mapping>
</web-app>
```



## 实现步骤

```java
class Bootstrap {
  public void static main(String[] args){
    Bootstrap.run();
  }
  
  public static void run() {
    // 1.初始化配置 server.xml && webapps/{app}/web.xml
    HelperLoader.init();
   	// 2.启动监听服务器 => 127.0.0.1:8080
    ServerSocket server = new ServerSocket(8080, "127.0.0.1");
    while(true){
      Socket client = server.accept();
      // 3.通知 => 处理请求并响应数据
      HandlerHelper.notify(client);
    }
  }
}
```

### 初始化配置

```java
HelperLoader.init() {
  ClassLoader.loadClass(ConfigHelper.class);
}

class ConfigHelper {
  @Getter
  private Map<String, Servlet> uri2servlet;
  @Getter
  private ExecutorService executorService;
  
  // port,host,appBase @Getter...
  
  static 
  {
    initServerConfig();	// parse server.xml => [port,host,appBase]
    initServletMapping();	// parse webapps/*/web.xml => uri2servlet<String, Servlet>
    initThreadPool();	// 请求线程池 => 解决socket客户端超时未响应导致服务端阻塞 => 保证每个客户端正常响应数据
  }
}
```

### 通知处理器

```java
HandlerHelper.notify(client) {
  // "GET /index.htm HTTP1.1 ..." => {method: "GET", uri: "/index.html"}
  HttpRequest request = wrapperRequest(client);
  // 输出内容:content => "HTTP content-type=text/html; content-body=${content}"
  handleRequest(client.getOutputStream(), request);
}
```

### 处理请求

```java
class StaticResourceHandler {
  void handle(HttpResponse response, HttpRequest request) {
    HttpUtil.write(response.getOutputStream(), request.getUri());
  }
}

class DynamicResourceHandler {
  void handle(HttpResponse response, HttpRequest request) {
    Servlet servlet = ConfigHelper.get(request.getUri());
    servlet.sevice(request, response);
  }
}
```