手写SpringMVC框架（一）-------项目搭建

SpringMVC处理请求的大致流程：



我们来开始着手手写一个SpringMVC框架。

新建一个springMVC项目，流程参见

SpringMVC框架搭建流程

引入servlet相关的jar包：

<dependency>

  <groupId>javax.servlet</groupId>

  <artifactId>javax.servlet-api</artifactId>

  <version>3.1.0</version>

</dependency>

新建一个servlet:

模拟springmvc，起名为LgDispatcherServlet

package com.lagou.edu.mvcframework.servlet;

import javax.servlet.http.HttpServlet;

/**

* @author liuyj

* @Title: LgDispatcherServlet

* @create 2020-06-11 14:22

* @ProjectName springmvc-demo

* @Description: TODO

*/

public class LgDispatcherServlet extends HttpServlet {

}

web.xml中注册我们新建的LgDispatcherServlet：

<servlet>

  <servlet-name>lgmvc</servlet-name>

  <servlet-class>com.lagou.edu.mvcframework.servlet.LgDispatcherServlet</servlet-class>

</servlet>

<servlet-mapping>

  <servlet-name>lgmvc</servlet-name>

  <url-pattern>/*</url-pattern>

</servlet-mapping>

新建几个自定义注解：

@Documented

@Target(ElementType.FIELD)

@Retention(RetentionPolicy.RUNTIME)

public @interface LagouAutowired {

     String value() default "";

}

@Documented

@Target(ElementType.TYPE)

@Retention(RetentionPolicy.RUNTIME)

public @interface LagouController {

     String value() default "";

}

@Documented

@Target({ElementType.TYPE,ElementType.METHOD})

@Retention(RetentionPolicy.RUNTIME)

public @interface LagouRequestMapping {

     String value() default "";

}

@Documented

@Target(ElementType.TYPE)

@Retention(RetentionPolicy.RUNTIME)

public @interface LagouService {

     String value() default "";

}

新建demo包下的service及implement实现类及controller并加上相应的注解：

service:

package com.lagou.edu.demo.service;

public interface IDemoService {

    String get(String name);

}

impl:

package com.lagou.edu.demo.service.impl;

import com.lagou.edu.demo.service.IDemoService;

import com.lagou.edu.mvcframework.annotations.LagouService;

@LagouService("demoService")

public class DemoServiceImpl implements IDemoService {

    @Override

    public String get(String name) {

        System.out.println("service 实现类中的name参数：" + name) ;

        return name;

    }

}

controller:

package com.lagou.edu.demo.controller;

import com.lagou.edu.demo.service.IDemoService;

import com.lagou.edu.mvcframework.annotations.LagouAutowired;

import com.lagou.edu.mvcframework.annotations.LagouController;

import com.lagou.edu.mvcframework.annotations.LagouRequestMapping;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@LagouController

@LagouRequestMapping("/demo")

public class DemoController {

    @LagouAutowired

    private IDemoService demoService;

    /**

     * URL: /demo/query?name=lisi

     * @param request

     * @param response

     * @param name

     * @return

     */

    @LagouRequestMapping("/query")

    public String query(HttpServletRequest request, HttpServletResponse response,String name) {

        return demoService.get(name);

    }

}

本节到此结束。

下一节我们来开始结构开发设计。

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