浅谈JavaWeb（一）—— Servlet

什么是Servlet?

Servlet其实就是Java提供的一个接口,同时也是处理网络请求的规范，是Java Web程序的基础。

Servlet能做什么？

Servlet由Servlet容器来统一管理，当浏览器向Web服务器发送一个请求后，Web服务器交给Servlet容器来处理，Servlet容器解析后决定哪个具体的Servlet去执行业务逻辑。Servlet执行后，回传请求结果，最后请求结果在浏览器呈现。

SpringBoot中怎么注册Servlet

1.使用注解

1.1 继承HttpServlet重写doGet与doPost，添加@WebServlet注解

@WebServlet(urlPatterns = "/self/info")
public class ServletTestDemo extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        PrintWriter printWriter=resp.getWriter();
        printWriter.println("");
        printWriter.println("");
        printWriter.println("");
        printWriter.println("
Servlet Display Demo
");
        printWriter.println("
Hello servlet
");
        printWriter.println("");
        printWriter.println("");
        printWriter.println("");
        printWriter.flush();
        printWriter.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

1.2 启动类添加注解 @ServletComponentScan，指定扫描的ServLet所在的包

@ServletComponentScan(basePackages = "com.forest.servelt")
@SpringBootApplication
public class ServletDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(ServletDemoApplication.class, args);
    }

}

2.配置类方式

2.1继承HttpServlet重写doGet与doPost

public class ServletTestDemo2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        PrintWriter printWriter=resp.getWriter();
        printWriter.println("");
        printWriter.println("");
        printWriter.println("");
        printWriter.println("
Servlet Display Demo
");
        printWriter.println("
Hello servlet By Config
");
        printWriter.println("");
        printWriter.println("");
        printWriter.println("");
        printWriter.flush();
        printWriter.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

2.2 定义配置类，实例化Servlet

@Configuration
public class ServletConfiguration {

    @Bean
    public ServletRegistrationBean myServletBean(){
        return new ServletRegistrationBean(new ServletTestDemo2(),"/getMyServlet");
    }

}