手寫SpringMVC框架（一）-------項目搭建

SpringMVC處理請求的大致流程：

我們來開始着手手寫一個SpringMVC框架。

新建一個springMVC項目，流程參見
SpringMVC框架搭建流程

引入servlet相關的jar包：

<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.1.0</version>
</dependency>

新建一個servlet:
模擬springmvc，起名爲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中註冊我們新建的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>

新建幾個自定義註解：

@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實現類及controller並加上相應的註解：
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 實現類中的name參數：" + 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);
    }
}

本節到此結束。
下一節我們來開始結構開發設計。

歡迎訪問：

微信公衆號（程序員資料站）：code_data