第七章用300行代码手写提炼Spring核心原理

1.1配置application.properties文件

scanPackage=com.gupaoedu.demo

1.2 配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>spring5</display-name>
    <servlet>
        <servlet-name>gpmvc</servlet-name>
        <servlet-class>com.gupaoedu.mvcframework.v1.servlet.GPDispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>application.properties</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>gpmvc</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

1.3自定义注解

@GPservice

package com.gupaoedu.mvcframework.annotation;

import java.lang.annotation.*;

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPService {
    String value()  default "";
}

@GPAutowired

package com.gupaoedu.mvcframework.annotation;

import java.lang.annotation.*;    

@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPAutowired {
    String value()  default "";
}

@GPController

package com.gupaoedu.mvcframework.annotation;

import java.lang.annotation.*;

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPController {
    String value() default "";
}

@GPRequestMapping

package com.gupaoedu.mvcframework.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPRequestMapping {
    String value()  default "";
}

@RequestParam

package com.gupaoedu.mvcframework.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPRequestParam {
    String value()  default "";
}

1.4.配置注解

接口 IDemoService

package com.gupaoedu.demo.service;

public interface IDemoService {
    public  String get(String  name);
}

实现类Demoservice

package com.gupaoedu.demo.service.impl;

import com.gupaoedu.demo.service.IDemoService;
import com.gupaoedu.mvcframework.annotation.GPService;
/**
 * DemoService
 * */
@GPService
public class DemoService implements IDemoService {

    @Override
    public String get(String name) {
        return "my name is "+name ;
    }
    
}

配置请求入口类DemoAction

package com.gupaoedu.demo.mvc.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gupaoedu.demo.service.IDemoService;
import com.gupaoedu.mvcframework.annotation.GPAutowired;
import com.gupaoedu.mvcframework.annotation.GPController;
import com.gupaoedu.mvcframework.annotation.GPRequestMapping;
import com.gupaoedu.mvcframework.annotation.GPRequestParam;

@GPController
@GPRequestMapping("/demo")
public class DemoAction {

    @GPAutowired
    private IDemoService demoService;

    @GPRequestMapping("/query")
    public void query(HttpServletRequest req, HttpServletResponse rsp, @GPRequestParam("name") String name) {
        String reString = demoService.get(name);
        try {
            rsp.getWriter().write(reString);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    @GPRequestMapping("/add")
    public void add(HttpServletRequest req, HttpServletResponse rsp, @GPRequestParam("a") Integer a, @GPRequestParam("b") Integer b) {
        try {
            rsp.getWriter().write(a +"+" +b +"="+ (a+b));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    @GPRequestMapping("/remove")
    private void remove(HttpServletRequest req, HttpServletResponse rsp, @GPRequestParam("id") String id) {
    }
}

2 容器初始化

2.1 实现1.0版本

package com.gupaoedu.mvcframework.v1.servlet;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gupaoedu.mvcframework.annotation.GPAutowired;
import com.gupaoedu.mvcframework.annotation.GPController;
import com.gupaoedu.mvcframework.annotation.GPRequestMapping;
import com.gupaoedu.mvcframework.annotation.GPService;

public class GPDispatcherServlet extends HttpServlet {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private Map<String, Object> mapping = new HashMap<String, Object>();
    private Map<String, Object> mapping2 = new HashMap<String, Object>();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        try {
            doDispatch(req, resp);
        } catch (Exception e) {
            resp.getWriter().write("500 Exception " + Arrays.toString(e.getStackTrace()));
        }
    }

    private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
        // TODO Auto-generated method stub
        String url = req.getRequestURI();
        String contextPath = req.getContextPath();
        url = url.replace(contextPath, "").replaceAll("/+", "/");
        System.out.println("url  " + url);

        for (Object object : mapping.keySet()) {
            System.out.println("mapping" + object);
        }
        if (!this.mapping.containsKey(url)) {
            resp.getWriter().write("404  NOT FOUND!!");
            return;
        }
        Method method = (Method) this.mapping.get(url);
        Map<String, String[]> params = req.getParameterMap();
        method.invoke(this.mapping.get(method.getDeclaringClass().getName()),
                new Object[] { req, resp, params.get("name")[0] });
    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        // TODO Auto-generated method stub
        InputStream is = null;
        try {
            Properties configContext = new Properties();

            is = this.getClass().getClassLoader().getResourceAsStream(config.getInitParameter("contextConfigLocation"));
            configContext.load(is);
            String scanPackage = configContext.getProperty("scanPackage");
            doScanner(scanPackage);

            System.out.println("1111111111");
            Set<String> set = mapping.keySet();
            for (String className : set) {
                if (!className.contains(".")) {
                    continue;
                }
                Class<?> clazz = Class.forName(className);
                if (clazz.isAnnotationPresent(GPController.class)) {
                    mapping2.put(className, clazz.newInstance());
                    String baseUrl = "";
                    if (clazz.isAnnotationPresent(GPRequestMapping.class)) {
                        GPRequestMapping requestMappng = clazz.getAnnotation(GPRequestMapping.class);
                        baseUrl = requestMappng.value();
                    }
                    Method[] methods = clazz.getMethods();
                    for (Method method : methods) {
                        if (!method.isAnnotationPresent(GPRequestMapping.class)) {
                            continue;
                        }
                        GPRequestMapping requestMappng = method.getAnnotation(GPRequestMapping.class);
                        String url = (baseUrl + "/" + requestMappng.value()).replaceAll("/+", "/");
                        mapping2.put(url, method);
                        System.out.println("Mapped " + url + "," + method);
                    }
                } else if (clazz.isAnnotationPresent(GPService.class)) {
                    GPService service = clazz.getAnnotation(GPService.class);
                    String beanName = service.value();
                    if ("".equals(beanName)) {
                        beanName = clazz.getName();
                    }
                    Object instance = clazz.newInstance();
                    mapping2.put(beanName, instance);
                    for (Class<?> i : clazz.getInterfaces()) {
                        mapping2.put(i.getName(), instance);
                    }
                } else {
                    continue;
                }
            }
            mapping.putAll(mapping2);
            for (Object object : mapping.values()) {
                if (object == null) {
                    continue;
                }
                Class<?> clazz = object.getClass();
                if (clazz.isAnnotationPresent(GPController.class)) {
                    Field[] fields = clazz.getDeclaredFields();
                    for (Field field : fields) {
                        if (!field.isAnnotationPresent(GPAutowired.class)) {
                            continue;
                        }
                        GPAutowired autowired = field.getAnnotation(GPAutowired.class);
                        String beanName = autowired.value();
                        if ("".equals(beanName)) {
                            beanName = field.getType().getName();
                        }
                        field.setAccessible(true);
                        try {
                            field.set(mapping.get(clazz.getName()), mapping.get(beanName));
                        } catch (IllegalArgumentException e) {
                            // TODO: handle exception
                            e.printStackTrace();
                        }
                    }
                }
            }
        } catch (Exception e) {
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (Exception e2) {
                    // TODO: handle exception
                    e2.printStackTrace();
                }
            }
        }
    }

    private void doScanner(String scanPackage) {
        URL url = this.getClass().getClassLoader().getResource("/" + scanPackage.replaceAll("\\.", "/"));
        File classDir = new File(url.getFile());
        for (File file : classDir.listFiles()) {
            if (file.isDirectory()) {
                doScanner(scanPackage + "." + file.getName());
            } else {
                if (!file.getName().endsWith(".class")) {
                    continue;
                }
                String clazzName = (scanPackage + "." + file.getName().replace(".class", ""));
                mapping.put(clazzName, null);
            }
        }

    }
}

posted on 2020-01-28 11:38 zxjest 阅读(884) 评论(0) 编辑收藏举报

刷新页面返回顶部

zxjest

公告