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从零写一个具有IOC-AOP-MVC功能的框架-学习笔记-11. MVC功能之http请求处理器的编写-简易框架最后...

1. 本章需要完成的内容：

完成ControllerRequestProcessor类的编写： Controller请求处理器
完成JspRequestProcessor类的编写：jsp资源请求处理
完成PreRequestProcessor类的编写：请求预处理,包括编码以及路径处理
完成StaticResourceRequestProcessor类的编写：静态资源请求处理，包括但不限于图片，css，以及js文件等, 转发到DefaultServlet

2. PreRequestProcessor类的编写

2.1 PreRequestProcessor类需要完成的代码

package org.myframework.mvc.processor.impl;

/**
 * @author wuyiccc
 * @date 2020/6/16 18:54
 * 岂曰无衣，与子同袍~
 */

import lombok.extern.slf4j.Slf4j;
import org.myframework.mvc.RequestProcessorChain;
import org.myframework.mvc.processor.RequestProcessor;

/**
 * 请求预处理,包括编码以及路径处理
 */
@Slf4j
public class PreRequestProcessor implements RequestProcessor {

    @Override
    public boolean process(RequestProcessorChain requestProcessorChain) throws Exception {

        // 1.设置请求编码，将其统一设置成UTF-8
        requestProcessorChain.getRequest().setCharacterEncoding("UTF-8");
        // 2.将请求路径末尾的/剔除，为后续匹配Controller请求路径做准备
        // （一般Controller的处理路径是/aaa/bbb，所以如果传入的路径结尾是/aaa/bbb/，
        // 就需要处理成/aaa/bbb）
        String requestPath = requestProcessorChain.getRequestPath();
        //http://localhost:8080/myframework requestPath="/"
        if (requestPath.length() > 1 && requestPath.endsWith("/")) {
            requestProcessorChain.setRequestPath(requestPath.substring(0, requestPath.length() - 1));
        }
        log.info("preprocess request {} {}", requestProcessorChain.getRequestMethod(), requestProcessorChain.getRequestPath());

        return true;
    }
}

2.2 PreRequestProcessor类相关代码讲解：

从零写一个具有IOC-AOP-MVC功能的框架-学习笔记-11. MVC功能之http请求处理器的编写-简易框架最后...

3. StaticResourceRequestProcessor类的编写

3.1 StaticResourceRequestProcessor类需要完成的代码:

package com.wuyiccc.helloframework.mvc.processor.impl;

import com.wuyiccc.helloframework.mvc.RequestProcessorChain;
import com.wuyiccc.helloframework.mvc.processor.RequestProcessor;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;

/**
 * @author wuyiccc
 * @date 2020/7/14 22:40
 * 岂曰无衣，与子同袍~
 */
@Slf4j
public class StaticResourceRequestProcessor implements RequestProcessor {


    public static final String DEFAULT_TOMCAT_SERVLET = "default";
    public static final String STATIC_RESOURCE_PREFIX = "/static/";

    //tomcat默认请求派发器RequestDispatcher的名称
    RequestDispatcher defaultDispatcher;

    public StaticResourceRequestProcessor(ServletContext servletContext) {
        this.defaultDispatcher = servletContext.getNamedDispatcher(DEFAULT_TOMCAT_SERVLET);
        if (this.defaultDispatcher == null) {
            throw new RuntimeException("There is no default tomcat servlet");
        }
        log.info("The default servlet for static resource is {}", DEFAULT_TOMCAT_SERVLET);
    }

    @Override
    public boolean process(RequestProcessorChain requestProcessorChain) throws Exception {

        //1.通过请求路径判断是否是请求的静态资源 webapp/static
        if (isStaticResource(requestProcessorChain.getRequestPath())) {
            //2.如果是静态资源，则将请求转发给default servlet处理
            defaultDispatcher.forward(requestProcessorChain.getRequest(), requestProcessorChain.getResponse());
            return false;
        }
        return true;
    }

    //通过请求路径前缀（目录）是否为静态资源 /static/
    private boolean isStaticResource(String path) {
        return path.startsWith(STATIC_RESOURCE_PREFIX);
    }

}

3.2 StaticResourceRequestProcessor类相关代码讲解：

从零写一个具有IOC-AOP-MVC功能的框架-学习笔记-11. MVC功能之http请求处理器的编写-简易框架最后...

4. JspRequestProcessor

4.1 JspRequestProcessor需要完成的代码：

package org.myframework.mvc.processor.impl;

import org.myframework.mvc.RequestProcessorChain;
import org.myframework.mvc.processor.RequestProcessor;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;

/**
 * @author wuyiccc
 * @date 2020/6/16 18:59
 * 岂曰无衣，与子同袍~
 */

/**
 * jsp资源请求处理
 */
public class JspRequestProcessor implements RequestProcessor {


    //jsp请求的RequestDispatcher的名称
    private static final String JSP_SERVLET = "jsp";
    //Jsp请求资源路径前缀
    private static final String JSP_RESOURCE_PREFIX = "/templates/";

    /**
     * jsp的RequestDispatcher,处理jsp资源
     */
    private RequestDispatcher jspServlet;

    public JspRequestProcessor(ServletContext servletContext) {
        jspServlet = servletContext.getNamedDispatcher(JSP_SERVLET);
        if (null == jspServlet) {
            throw new RuntimeException("there is no jsp servlet");
        }
    }

    @Override
    public boolean process(RequestProcessorChain requestProcessorChain) throws Exception {
        if (isJspResource(requestProcessorChain.getRequestPath())) {
            jspServlet.forward(requestProcessorChain.getRequest(), requestProcessorChain.getResponse());
            return false;
        }
        return true;
    }

    /**
     * 是否请求的是jsp资源
     */
    private boolean isJspResource(String url) {
        return url.startsWith(JSP_RESOURCE_PREFIX);
    }
}

4.2 JspRequestProcessor相关代码讲解：

从零写一个具有IOC-AOP-MVC功能的框架-学习笔记-11. MVC功能之http请求处理器的编写-简易框架最后...

5. ControllerRequestProcessor类的编写

5.1 ControllerRequestProcessor需要完成的代码:

package org.myframework.mvc.processor.impl;

import lombok.extern.slf4j.Slf4j;
import org.myframework.core.BeanContainer;
import org.myframework.mvc.RequestProcessorChain;
import org.myframework.mvc.annotation.RequestMapping;
import org.myframework.mvc.annotation.RequestParam;
import org.myframework.mvc.annotation.ResponseBody;
import org.myframework.mvc.processor.RequestProcessor;
import org.myframework.mvc.render.JsonResultRender;
import org.myframework.mvc.render.ResourceNotFoundResultRender;
import org.myframework.mvc.render.ResultRender;
import org.myframework.mvc.render.ViewResultRender;
import org.myframework.mvc.type.ControllerMethod;
import org.myframework.mvc.type.RequestPathInfo;
import org.myframework.util.ConverterUtil;
import org.myframework.util.ValidationUtil;

import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author wuyiccc
 * @date 2020/6/16 19:14
 * 岂曰无衣，与子同袍~
 */

/**
 * Controller请求处理器
 */
@Slf4j
public class ControllerRequestProcessor implements RequestProcessor {

    //IOC容器
    private BeanContainer beanContainer;

    //请求和controller方法的映射集合
    private Map<RequestPathInfo, ControllerMethod> pathControllerMethodMap = new ConcurrentHashMap<>();


    /**
     * 依靠容器的能力，建立起请求路径、请求方法与Controller方法实例的映射
     */
    public ControllerRequestProcessor() {
        this.beanContainer = BeanContainer.getInstance();
        Set<Class<?>> requestMappingSet = beanContainer.getClassesByAnnotation(RequestMapping.class);
        initPathControllerMethodMap(requestMappingSet);
    }

    private void initPathControllerMethodMap(Set<Class<?>> requestMappingSet) {

        if (ValidationUtil.isEmpty(requestMappingSet)) {
            return;
        }

        //1.遍历所有被@RequestMapping标记的类，获取类上面该注解的属性值作为一级路径
        for (Class<?> requestMappingClass : requestMappingSet) {

            RequestMapping requestMapping = requestMappingClass.getAnnotation(RequestMapping.class);
            String basePath = requestMapping.value();
            if (!basePath.startsWith("/")) {
                basePath = "/" + basePath;
            }

            //2.遍历类里所有被@RequestMapping标记的方法，获取方法上面该注解的属性值，作为二级路径
            Method[] methods = requestMappingClass.getDeclaredMethods();
            if (ValidationUtil.isEmpty(methods)) {
                continue;
            }

            for (Method method : methods) {

                if (method.isAnnotationPresent(RequestMapping.class)) {

                    RequestMapping methodRequest = method.getAnnotation(RequestMapping.class);
                    String methodPath = methodRequest.value();

                    if (!methodPath.startsWith("/")) {
                        methodPath = "/" + basePath;
                    }


                    String url = basePath + methodPath;

                    //3.解析方法里被@RequestParam标记的参数，
                    // 获取该注解的属性值，作为参数名，
                    // 获取被标记的参数的数据类型，建立参数名和参数类型的映射
                    Map<String, Class<?>> methodParams = new HashMap<>();

                    Parameter[] parameters = method.getParameters();

                    if (!ValidationUtil.isEmpty(parameters)) {

                        for (Parameter parameter : parameters) {

                            RequestParam param = parameter.getAnnotation(RequestParam.class);

                            //目前暂定为Controller方法里面所有的参数都需要@RequestParam注解
                            if (param == null) {
                                throw new RuntimeException("The parameter must have @RequestParam");
                            }

                            methodParams.put(param.value(), parameter.getType());
                        }
                    }

                    //4.将获取到的信息封装成RequestPathInfo实例和ControllerMethod实例，放置到映射表里
                    String httpMethod = String.valueOf(methodRequest.method());

                    RequestPathInfo requestPathInfo = new RequestPathInfo(httpMethod, url);

                    if (this.pathControllerMethodMap.containsKey(requestPathInfo)) {
                        log.warn("duplicate url:{} registration，current class {} method{} will override the former one",
                                requestPathInfo.getHttpPath(), requestMappingClass.getName(), method.getName());
                    }

                    ControllerMethod controllerMethod = new ControllerMethod(requestMappingClass, method, methodParams);

                    this.pathControllerMethodMap.put(requestPathInfo, controllerMethod);
                }
            }
        }

    }

    @Override
    public boolean process(RequestProcessorChain requestProcessorChain) throws Exception {

        //1.解析HttpServletRequest的请求方法,请求路径，获取对应的ControllerMethod实例
        String method = requestProcessorChain.getRequestMethod();
        String path = requestProcessorChain.getRequestPath();

        ControllerMethod controllerMethod = this.pathControllerMethodMap.get(new RequestPathInfo(method, path));

        if (controllerMethod == null) {
            requestProcessorChain.setResultRender(new ResourceNotFoundResultRender(method, path));
            return false;
        }

        //2.解析请求参数，并传递给获取到的ControllerMethod实例去执行
        Object result = invokeControllerMethod(controllerMethod, requestProcessorChain.getRequest());

        //3.根据处理的结果，选择对应的render进行渲染
        setResultRender(result, controllerMethod, requestProcessorChain);

        return true;
    }


    /**
     * 根据不同情况设置不同的渲染器
     */
    private void setResultRender(Object result, ControllerMethod controllerMethod, RequestProcessorChain requestProcessorChain) {

        if (result == null) {
            return;
        }

        ResultRender resultRender;

        boolean isJson = controllerMethod.getInvokeMethod().isAnnotationPresent(ResponseBody.class);
        if (isJson) {
            resultRender = new JsonResultRender(result);
        } else {
            resultRender = new ViewResultRender(result);
        }

        requestProcessorChain.setResultRender(resultRender);
    }

    private Object invokeControllerMethod(ControllerMethod controllerMethod, HttpServletRequest request) {

        //1.从请求里获取GET或者POST的参数名及其对应的值
        Map<String, String> requestParamMap = new HashMap<>();

        //GET，POST方法的请求参数获取方式
        Map<String, String[]> parameterMap = request.getParameterMap();

        for (Map.Entry<String, String[]> parameter : parameterMap.entrySet()) {

            if (!ValidationUtil.isEmpty(parameter.getValue())) {
                //只支持一个参数对应一个值的形式
                requestParamMap.put(parameter.getKey(), parameter.getValue()[0]);
            }

        }

        //2.根据获取到的请求参数名及其对应的值，以及controllerMethod里面的参数和类型的映射关系，去实例化出方法对应的参数
        List<Object> methodParams = new ArrayList<>();

        Map<String, Class<?>> methodParamMap = controllerMethod.getMethodParameters();


        for (String paramName : methodParamMap.keySet()) {

            Class<?> type = methodParamMap.get(paramName);
            String requestValue = requestParamMap.get(paramName);
            Object value;

            //只支持String 以及基础类型char,int,short,byte,double,long,float,boolean,及它们的包装类型
            if (requestValue == null) {
                //将请求里的参数值转成适配于参数类型的空值
                value = ConverterUtil.primitiveNull(type);
            } else {
                value = ConverterUtil.convert(type, requestValue);
            }
            methodParams.add(value);

        }

        //3.执行Controller里面对应的方法并返回结果
        Object controller = beanContainer.getBean(controllerMethod.getControllerClass());
        Method invokeMethod = controllerMethod.getInvokeMethod();
        invokeMethod.setAccessible(true);
        Object result;

        try {

            if (methodParams.size() == 0) {
                result = invokeMethod.invoke(controller);
            } else {
                result = invokeMethod.invoke(controller, methodParams.toArray());
            }

        } catch (InvocationTargetException e) {
            //如果是调用异常的话，需要通过e.getTargetException()
            // 去获取执行方法抛出的异常
            throw new RuntimeException(e.getTargetException());
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }

        return result;
    }
}