1. 本章需要完成的内容

1. 完成请求处理器接口RequestProcessor的编写
2. 完成ResultRender渲染器接口的编写
3. 完成DefultResultRender默认渲染器类的编写
4. 完成InternalErrorResultRender内部异常渲染器类的编写
5. 完成JsonResultRender Json渲染器类的编写
6. 完成ResourceNotFoundResultRender 资源未找到时使用的渲染器类编写
7. 完成ViewResultRender 页面渲染器类的编写
8. 完成DispatcherServlet http请求拦截器的编写
9. 完成RequestProcessorChain 责任链类的编写

2. 第一部分内容

1. 该部分完成DispatcherServlet与RequestProcessorChain类的编写

2.1 DispatcherServlet类

2.1.1 需要完成的代码如下：

package com.wuyiccc.helloframework.mvc;import com.wuyiccc.helloframework.aop.AspectWeaver;
import com.wuyiccc.helloframework.core.BeanContainer;
import com.wuyiccc.helloframework.injection.DependencyInjector;
import com.wuyiccc.helloframework.mvc.processor.RequestProcessor;
import com.wuyiccc.helloframework.mvc.processor.impl.ControllerRequestProcessor;
import com.wuyiccc.helloframework.mvc.processor.impl.JspRequestProcessor;
import com.wuyiccc.helloframework.mvc.processor.impl.PreRequestProcessor;
import com.wuyiccc.helloframework.mvc.processor.impl.StaticResourceRequestProcessor;
import lombok.extern.slf4j.Slf4j;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;/*** @author wuyiccc* @date 2020/7/14 21:42* 岂曰无衣，与子同袍~*/
@WebServlet("/*")
@Slf4j
public class DispatcherServlet extends HttpServlet {private static final String HELLOFRAMEWORK_CONFIG_FILE = "config/helloframework-config.properties";private List<RequestProcessor> PROCESSOR = new ArrayList<>();@Overridepublic void init() throws ServletException {// 1. 初始化容器BeanContainer beanContainer = BeanContainer.getInstance();beanContainer.loadBeans(getHelloFrameworkScanPackages());new AspectWeaver().doAop();new DependencyInjector().doIoc();// 2. 初始化请求处理器责任链PROCESSOR.add(new PreRequestProcessor());PROCESSOR.add(new StaticResourceRequestProcessor(getServletContext()));PROCESSOR.add(new JspRequestProcessor(getServletContext()));PROCESSOR.add(new ControllerRequestProcessor());}@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 1. 创建责任链对象实例RequestProcessorChain requestProcessorChain = new RequestProcessorChain(PROCESSOR.iterator(), req, resp);// 2. 通过责任链模式来依次调用请求处理器对请求进行处理requestProcessorChain.doRequestProcessorChain();// 3. 对处理结果进行渲染requestProcessorChain.doRender();}private String getHelloFrameworkScanPackages() {Properties properties = new Properties();InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream(HELLOFRAMEWORK_CONFIG_FILE);try {properties.load(in);} catch (IOException e) {log.warn("The config/helloframework.properties can not load");e.printStackTrace();}String scanPackages = properties.getProperty("helloframework.scan.packages");log.info("this is scanPackages: {}", scanPackages);return scanPackages;}
}

2.1.2 DIspatcherServlet类相关代码讲解：

2.2 RequestProcessorChain类

2.2.1 需要完成的代码如下:

package org.myframework.mvc;/*** @author wuyiccc* @date 2020/6/16 18:48* 岂曰无衣，与子同袍~*/import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.myframework.mvc.processor.RequestProcessor;
import org.myframework.mvc.render.DefaultResultRender;
import org.myframework.mvc.render.InternalErrorResultRender;
import org.myframework.mvc.render.ResultRender;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Iterator;/*** 1. 以责任链的模式执行注册的请求处理器* 2. 委派给特定的Render实例对处理后的结果进行渲染*/
@Data
@Slf4j
public class RequestProcessorChain {// 请求处理器迭代器private Iterator<RequestProcessor> requestProcessorIterator;private HttpServletRequest request;private HttpServletResponse response;// http请求方法private String requestMethod;// http请求路径private String requestPath;// http响应状态码private int responseCode;// 请求结果渲染器private ResultRender resultRender;public RequestProcessorChain(Iterator<RequestProcessor> requestProcessorIterator, HttpServletRequest request, HttpServletResponse response) {this.requestProcessorIterator = requestProcessorIterator;this.request = request;this.response = response;this.requestMethod = request.getMethod();this.requestPath = request.getPathInfo();this.responseCode = HttpServletResponse.SC_OK;}/*** 以责任链的模式执行请求链*/public void doRequestProcessorChain() {// 1. 通过迭代器遍历注册的请求处理器实现类列表try {while (requestProcessorIterator.hasNext()) {// 2. 知道某个请求处理器执行后返回为false为止if (!requestProcessorIterator.next().process(this)) {break;}}} catch (Exception e) {// 3. 期间如果出现异常，则交给内部异常渲染器处理this.resultRender = new InternalErrorResultRender(e.getMessage());log.error("doRequestProcessorChain error: ", e);}}/*** 执行处理器*/public void doRender() {// 1. 如果请求处理器实现类均未选择合适的渲染器，则使用默认的if (this.resultRender == null) {this.resultRender = new DefaultResultRender();}// 2. 调用渲染器的render方法对结果进行渲染try {this.resultRender.render(this);} catch (Exception e) {log.error("doRender error: ", e);throw new RuntimeException(e);}}
}

2.2.2 RequestProcessorChain相关代码讲解如下:

3. 第二部分需要完成的内容： 结果渲染器的编写

3.1 DefaultResultRender类的编写及讲解：

3.2 InternalErrorResultRender类的编写及讲解：

3.3 JsonResultRender类的编写及讲解:

3.4 ResourceNotFoundResultRender类的编写及讲解:

3.5 ViewResultRender类的编写及讲解：

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