1. 本章需要完成的內容：

1. 完成ControllerRequestProcessor類的編寫： Controller請求處理器
2. 完成JspRequestProcessor類的編寫：jsp資源請求處理
3. 完成PreRequestProcessor類的編寫： 請求預處理,包括編碼以及路徑處理
4. 完成StaticResourceRequestProcessor類的編寫： 靜態資源請求處理，包括但不限於圖片，css，以及js檔案等, 轉發到DefaultServlet

2. PreRequestProcessor類的編寫

2.1 PreRequestProcessor類需要完成的程式碼

package org.myframework.mvc.processor.impl;

/**
 * @author wuyiccc
 * @date 2020/6/16 18:54
 * 豈曰無衣，與子同袍~
 */

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

/**
 * 請求預處理,包括編碼以及路徑處理
 */
@Slf4j
public class PreRequestProcessor implements RequestProcessor {

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

        // 1.設定請求編碼，將其統一設定成UTF-8
        requestProcessorChain.getRequest().setCharacterEncoding("UTF-8");
        // 2.將請求路徑末尾的/剔除，為後續匹配Controller請求路徑做準備
        // （一般Controller的處理路徑是/aaa/bbb，所以如果傳入的路徑結尾是/aaa/bbb/，
        // 就需要處理成/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類相關程式碼講解：

3. StaticResourceRequestProcessor類的編寫

3.1 StaticResourceRequestProcessor類需要完成的程式碼:

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
 * 豈曰無衣，與子同袍~
 */
@Slf4j
public class StaticResourceRequestProcessor implements RequestProcessor {


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

    //tomcat預設請求派發器RequestDispatcher的名稱
    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.通過請求路徑判斷是否是請求的靜態資源 webapp/static
        if (isStaticResource(requestProcessorChain.getRequestPath())) {
            //2.如果是靜態資源，則將請求轉發給default servlet處理
            defaultDispatcher.forward(requestProcessorChain.getRequest(), requestProcessorChain.getResponse());
            return false;
        }
        return true;
    }

    //通過請求路徑字首（目錄）是否為靜態資源 /static/
    private boolean isStaticResource(String path) {
        return path.startsWith(STATIC_RESOURCE_PREFIX);
    }

}

3.2 StaticResourceRequestProcessor類相關程式碼講解：

4. JspRequestProcessor

4.1 JspRequestProcessor需要完成的程式碼：

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
 * 豈曰無衣，與子同袍~
 */

/**
 * jsp資源請求處理
 */
public class JspRequestProcessor implements RequestProcessor {


    //jsp請求的RequestDispatcher的名稱
    private static final String JSP_SERVLET = "jsp";
    //Jsp請求資源路徑字首
    private static final String JSP_RESOURCE_PREFIX = "/templates/";

    /**
     * jsp的RequestDispatcher,處理jsp資源
     */
    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;
    }

    /**
     * 是否請求的是jsp資源
     */
    private boolean isJspResource(String url) {
        return url.startsWith(JSP_RESOURCE_PREFIX);
    }
}

4.2 JspRequestProcessor相關程式碼講解：

5. ControllerRequestProcessor類的編寫

5.1 ControllerRequestProcessor需要完成的程式碼:

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
 * 豈曰無衣，與子同袍~
 */

/**
 * Controller請求處理器
 */
@Slf4j
public class ControllerRequestProcessor implements RequestProcessor {

    //IOC容器
    private BeanContainer beanContainer;

    //請求和controller方法的對映集合
    private Map<RequestPathInfo, ControllerMethod> pathControllerMethodMap = new ConcurrentHashMap<>();


    /**
     * 依靠容器的能力，建立起請求路徑、請求方法與Controller方法例項的對映
     */
    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.遍歷所有被@RequestMapping標記的類，獲取類上面該註解的屬性值作為一級路徑
        for (Class<?> requestMappingClass : requestMappingSet) {

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

            //2.遍歷類裡所有被@RequestMapping標記的方法，獲取方法上面該註解的屬性值，作為二級路徑
            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.解析方法裡被@RequestParam標記的引數，
                    // 獲取該註解的屬性值，作為引數名，
                    // 獲取被標記的引數的資料型別，建立引數名和引數型別的對映
                    Map<String, Class<?>> methodParams = new HashMap<>();

                    Parameter[] parameters = method.getParameters();

                    if (!ValidationUtil.isEmpty(parameters)) {

                        for (Parameter parameter : parameters) {

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

                            //目前暫定為Controller方法裡面所有的引數都需要@RequestParam註解
                            if (param == null) {
                                throw new RuntimeException("The parameter must have @RequestParam");
                            }

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

                    //4.將獲取到的資訊封裝成RequestPathInfo例項和ControllerMethod例項，放置到對映表裡
                    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的請求方法,請求路徑，獲取對應的ControllerMethod例項
        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.解析請求引數，並傳遞給獲取到的ControllerMethod例項去執行
        Object result = invokeControllerMethod(controllerMethod, requestProcessorChain.getRequest());

        //3.根據處理的結果，選擇對應的render進行渲染
        setResultRender(result, controllerMethod, requestProcessorChain);

        return true;
    }


    /**
     * 根據不同情況設定不同的渲染器
     */
    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.從請求裡獲取GET或者POST的引數名及其對應的值
        Map<String, String> requestParamMap = new HashMap<>();

        //GET，POST方法的請求引數獲取方式
        Map<String, String[]> parameterMap = request.getParameterMap();

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

            if (!ValidationUtil.isEmpty(parameter.getValue())) {
                //只支援一個引數對應一個值的形式
                requestParamMap.put(parameter.getKey(), parameter.getValue()[0]);
            }

        }

        //2.根據獲取到的請求引數名及其對應的值，以及controllerMethod裡面的引數和型別的對映關係，去例項化出方法對應的引數
        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;

            //只支援String 以及基礎型別char,int,short,byte,double,long,float,boolean,及它們的包裝型別
            if (requestValue == null) {
                //將請求裡的引數值轉成適配於引數型別的空值
                value = ConverterUtil.primitiveNull(type);
            } else {
                value = ConverterUtil.convert(type, requestValue);
            }
            methodParams.add(value);

        }

        //3.執行Controller裡面對應的方法並返回結果
        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) {
            //如果是呼叫異常的話，需要通過e.getTargetException()
            // 去獲取執行方法丟擲的異常
            throw new RuntimeException(e.getTargetException());
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }

        return result;
    }
}

5.2 ControllerRequestProcessor相關程式碼講解

6. ConverterUtil值轉換工具類的補充

相關程式碼如下:

package com.wuyiccc.helloframework.util;

/**
 * @author wuyiccc
 * @date 2020/7/15 8:02
 * 豈曰無衣，與子同袍~
 */
public class ConverterUtil {

    /**
     * 返回基本資料型別的空值
     * 需要特殊處理的基本型別即int\double\short\long\byte\float\boolean
     *
     * @param type 引數型別
     * @return 對應的空值
     */
    public static Object primitiveNull(Class<?> type) {

        if (type == int.class || type == double.class || type == short.class || type == long.class || type == byte.class || type == float.class) {
            return 0;
        } else if (type == boolean.class) {
            return false;
        }
        return null;
    }


    /**
     * String型別轉換成對應的引數型別
     *
     * @param type         引數型別
     * @param requestValue 值
     * @return 轉換後的Object
     */
    public static Object convert(Class<?> type, String requestValue) {

        if (isPrimitive(type)) {

            if (ValidationUtil.isEmpty(requestValue)) {
                return primitiveNull(type);
            }

            if (type.equals(int.class) || type.equals(Integer.class)) {

                return Integer.parseInt(requestValue);
            } else if (type.equals(String.class)) {

                return requestValue;
            } else if (type.equals(Double.class) || type.equals(double.class)) {

                return Double.parseDouble(requestValue);
            } else if (type.equals(Float.class) || type.equals(float.class)) {

                return Float.parseFloat(requestValue);
            } else if (type.equals(Long.class) || type.equals(long.class)) {

                return Long.parseLong(requestValue);
            } else if (type.equals(Boolean.class) || type.equals(boolean.class)) {

                return Boolean.parseBoolean(requestValue);
            } else if (type.equals(Short.class) || type.equals(short.class)) {

                return Short.parseShort(requestValue);
            } else if (type.equals(Byte.class) || type.equals(byte.class)) {

                return Byte.parseByte(requestValue);
            }

            return requestValue;
        } else {
            throw new RuntimeException("count not support non primitive type conversion yet");
        }

    }


    /**
     * 判定是否基本資料型別(包括包裝類以及String)
     *
     * @param type 引數型別
     * @return 是否為基本資料型別
     */
    private static boolean isPrimitive(Class<?> type) {
        return type == boolean.class
                || type == Boolean.class
                || type == double.class
                || type == Double.class
                || type == float.class
                || type == Float.class
                || type == short.class
                || type == Short.class
                || type == int.class
                || type == Integer.class
                || type == long.class
                || type == Long.class
                || type == String.class
                || type == byte.class
                || type == Byte.class
                || type == char.class
                || type == Character.class;
    }
}

github地址：https://github.com/wuyiccc/he...