SpringMVC之手写MVC框架
作者:互联网
SpringMVC之手写MVC框架
学习资料:拉勾课程《Java高薪训练营》
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<!--部署到服务器后不再使用该servlet,而使用tomcat的servlet-->
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.9</version>
</dependency>
</dependencies>
<build>
<plugins>
<!--编译插件定义编译细节-->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>11</source>
<target>11</target>
<encoding>utf-8</encoding>
<!--告诉编译器,编译的时候记录下形参的真实名称-->
<compilerArgs>
<arg>-parameters</arg>
</compilerArgs>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
<configuration>
<port>8080</port>
<path>/</path>
</configuration>
</plugin>
</plugins>
</build>
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MrdController
package com.mrd.edu.mvcframework.annotations; import java.lang.annotation.*; @Documented @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface MrdController { String value() default ""; }
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MrdService
package com.mrd.edu.mvcframework.annotations; import java.lang.annotation.*; @Documented @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface MrdService { String value() default ""; }
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MrdAutowired
package com.mrd.edu.mvcframework.annotations; import java.lang.annotation.*; @Documented @Target(ElementType.FIELD) @Retention(RetentionPolicy.RUNTIME) public @interface MrdAutowired { String value() default ""; }
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MrdRequestMapping
package com.mrd.edu.mvcframework.annotations; import java.lang.annotation.*; @Documented @Target({ElementType.TYPE,ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) public @interface MrdRequestMapping { String value() default ""; }
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⼿写MVC框架之 DemoController
package com.mrd.demo.controller; import com.mrd.demo.service.IDemoService; import com.mrd.edu.mvcframework.annotations.MrdAutowired; import com.mrd.edu.mvcframework.annotations.MrdController; import com.mrd.edu.mvcframework.annotations.MrdRequestMapping; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @MrdController @MrdRequestMapping("/demo") public class DemoController { @MrdAutowired private IDemoService demoService; /** * URL: /demo/query?name=lisi * * @param request * @param response * @param name * @return */ @MrdRequestMapping("/query") public String query(HttpServletRequest request, HttpServletResponse response, String name) { return demoService.get(name); } }
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⼿写MVC框架之 IDemoService
package com.mrd.demo.service; public interface IDemoService { String get(String name); }
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⼿写MVC框架之 DemoServiceImpl
package com.mrd.demo.service.impl; import com.mrd.demo.service.IDemoService; import com.mrd.edu.mvcframework.annotations.MrdService; @MrdService("demoService") public class DemoServiceImpl implements IDemoService { @Override public String get(String name) { System.out.println("service 实现类中的name参数:" + name); return name; } }
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⼿写MVC框架之 扫描包配置 springmvc.properties
scanPackage=com.mrd.demo
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⼿写MVC框架之 Handler
package com.mrd.edu.mvcframework.pojo; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; import java.util.regex.Pattern; /** * 封装handler方法相关的信息 */ public class Handler { private Object controller; // method.invoke(obj,) private Method method; private Pattern pattern; // spring中url是支持正则的 private Map<String, Integer> paramIndexMapping; // 参数顺序,是为了进行参数绑定,key是参数名,value代表是第几个参数 <name,2> public Handler(Object controller, Method method, Pattern pattern) { this.controller = controller; this.method = method; this.pattern = pattern; this.paramIndexMapping = new HashMap<>(); } public Object getController() { return controller; } public void setController(Object controller) { this.controller = controller; } public Method getMethod() { return method; } public void setMethod(Method method) { this.method = method; } public Pattern getPattern() { return pattern; } public void setPattern(Pattern pattern) { this.pattern = pattern; } public Map<String, Integer> getParamIndexMapping() { return paramIndexMapping; } public void setParamIndexMapping(Map<String, Integer> paramIndexMapping) { this.paramIndexMapping = paramIndexMapping; } }
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⼿写MVC框架之 前端控制器 MrdDispatcherServlet
package com.mrd.edu.mvcframework.servlet; import com.mrd.edu.mvcframework.annotations.MrdAutowired; import com.mrd.edu.mvcframework.annotations.MrdController; import com.mrd.edu.mvcframework.annotations.MrdRequestMapping; import com.mrd.edu.mvcframework.annotations.MrdService; import com.mrd.edu.mvcframework.pojo.Handler; import org.apache.commons.lang3.StringUtils; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Parameter; import java.util.*; import java.util.regex.Matcher; import java.util.regex.Pattern; public class MrdDispatcherServlet extends HttpServlet { private Properties properties = new Properties(); // 缓存扫描到的类的全限定类名 private List<String> classNames = new ArrayList<>(); // ioc容器 private Map<String, Object> ioc = new HashMap<String, Object>(); // handlerMapping //private Map<String,Method> handlerMapping = now HashMap<>(); // 存储url和Method之间的映射关系 private List<Handler> handlerMapping = new ArrayList<>(); @Override public void init(ServletConfig config) throws ServletException { // 1 加载配置文件 springmvc.properties String contextConfigLocation = config.getInitParameter("contextConfigLocation"); doLoadConfig(contextConfigLocation); // 2 扫描相关的类,扫描注解 doScan(properties.getProperty("scanPackage")); // 3 初始化bean对象(实现ioc容器,基于注解) doInstance(); // 4 实现依赖注入 doAutoWired(); // 5 构造一个HandlerMapping处理器映射器,将配置好的url和Method建立映射关系 initHandlerMapping(); System.out.println("Mrd mvc 初始化完成...."); // 6.等待请求进入,处理请求 } /* 构造一个HandlerMapping处理器映射器 最关键的环节 目的:将url和method建立关联 */ private void initHandlerMapping() { if (ioc.isEmpty()) { return; } for (Map.Entry<String, Object> entry : ioc.entrySet()) { // 获取ioc中当前遍历的对象的class类型 Class<?> aClass = entry.getValue().getClass(); //如果未包含@MrdController,则continue if (!aClass.isAnnotationPresent(MrdController.class)) { continue; } String baseUrl = ""; if (aClass.isAnnotationPresent(MrdRequestMapping.class)) { MrdRequestMapping annotation = aClass.getAnnotation(MrdRequestMapping.class); baseUrl = annotation.value(); // 等同于/demo } // 获取方法 Method[] methods = aClass.getMethods(); for (int i = 0; i < methods.length; i++) { Method method = methods[i]; // 方法没有标识MrdRequestMapping,就不处理 if (!method.isAnnotationPresent(MrdRequestMapping.class)) { continue; } // 如果标识,就处理 MrdRequestMapping annotation = method.getAnnotation(MrdRequestMapping.class); String methodUrl = annotation.value(); // 等同于/query String url = baseUrl + methodUrl; // 计算出来的url /demo/query // 把method所有信息及url封装为一个Handler Handler handler = new Handler(entry.getValue(), method, Pattern.compile(url)); // 计算方法的参数位置信息 // query(HttpServletRequest request, HttpServletResponse response,String name) //拿到参数信息 Parameter[] parameters = method.getParameters(); for (int j = 0; j < parameters.length; j++) { Parameter parameter = parameters[j]; if (parameter.getType() == HttpServletRequest.class || parameter.getType() == HttpServletResponse.class) { // 如果是request和response对象,那么参数名称写HttpServletRequest和HttpServletResponse handler.getParamIndexMapping().put(parameter.getType().getSimpleName(), j); } else { handler.getParamIndexMapping().put(parameter.getName(), j); // <name,2> } } // 建立url和method之间的映射关系(map缓存起来) handlerMapping.add(handler); } } } // 实现依赖注入 private void doAutoWired() { if (ioc.isEmpty()) { return; } // 有对象,再进行依赖注入处理 // 遍历ioc中所有对象,查看对象中的字段,是否有@MrdAutowired注解,如果有需要维护依赖注入关系 for (Map.Entry<String, Object> entry : ioc.entrySet()) { // 获取bean对象中的字段信息 Field[] declaredFields = entry.getValue().getClass().getDeclaredFields(); // 遍历判断处理 for (int i = 0; i < declaredFields.length; i++) { Field declaredField = declaredFields[i]; // @MrdAutowired private IDemoService demoService; if (!declaredField.isAnnotationPresent(MrdAutowired.class)) { continue; } // 有该注解 MrdAutowired annotation = declaredField.getAnnotation(MrdAutowired.class); String beanName = annotation.value(); // 需要注入的bean的id if ("".equals(beanName.trim())) { // 没有配置具体的bean id,那就需要根据当前字段类型注入(接口注入) IDemoService beanName = declaredField.getType().getName(); } // 开启赋值 declaredField.setAccessible(true); try { declaredField.set(entry.getValue(), ioc.get(beanName)); } catch (IllegalAccessException e) { e.printStackTrace(); } } } } // ioc容器 // 基于classNames缓存的类的全限定类名,以及反射技术,完成对象创建和管理 private void doInstance() { if (classNames.size() == 0) return; try { for (int i = 0; i < classNames.size(); i++) { String className = classNames.get(i); // com.mrd.demo.controller.DemoController // 反射 Class<?> aClass = Class.forName(className); // 区分controller,区分service if (aClass.isAnnotationPresent(MrdController.class)) { // controller的id此处不做过多处理,不取value了,就拿类的首字母小写作为id,保存到ioc中 String simpleName = aClass.getSimpleName();// DemoController //key:首字母小写转换 String lowerFirstSimpleName = lowerFirst(simpleName); // demoController //value:实例化 Object o = aClass.newInstance(); //保存到IOC容器中 ioc.put(lowerFirstSimpleName, o); } else if (aClass.isAnnotationPresent(MrdService.class)) { MrdService annotation = aClass.getAnnotation(MrdService.class); //获取注解value值 String beanName = annotation.value(); // 如果指定了id,就以指定的为准 if (!"".equals(beanName.trim())) { ioc.put(beanName, aClass.newInstance()); } else { // 如果没有指定,就以类名首字母小写 beanName = lowerFirst(aClass.getSimpleName()); ioc.put(beanName, aClass.newInstance()); } // service层往往是有接口的,面向接口开发,此时再以接口名为id,放入一份对象到ioc中,便于后期根据接口类型注入 Class<?>[] interfaces = aClass.getInterfaces(); for (int j = 0; j < interfaces.length; j++) { Class<?> anInterface = interfaces[j]; // 以接口的全限定类名作为id放入 ioc.put(anInterface.getName(), aClass.newInstance()); } } else { continue; } } } catch (Exception e) { e.printStackTrace(); } } // 首字母小写方法 public String lowerFirst(String str) { char[] chars = str.toCharArray(); if ('A' <= chars[0] && chars[0] <= 'Z') { chars[0] += 32; } return String.valueOf(chars); } // 扫描类 // scanPackage: com.mrd.demo package----> 磁盘上的文件夹(File) com/mrd/demo private void doScan(String scanPackage) { //磁盘上的路径 String scanPackagePath = Thread.currentThread().getContextClassLoader().getResource("").getPath() + scanPackage.replaceAll("\\.", "/"); File pack = new File(scanPackagePath); File[] files = pack.listFiles(); for (File file : files) { if (file.isDirectory()) { // 子package // 递归 doScan(scanPackage + "." + file.getName()); // com.mrd.demo.controller } else if (file.getName().endsWith(".class")) { String className = scanPackage + "." + file.getName().replaceAll(".class", ""); classNames.add(className); } } } // 加载配置文件 private void doLoadConfig(String contextConfigLocation) { //读取配置文件,得到输入流 InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation); try { properties.load(resourceAsStream); } catch (IOException e) { e.printStackTrace(); } } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 处理请求:根据url,找到对应的Method方法,进行调用 // 获取uri // String requestURI = req.getRequestURI(); // Method method = handlerMapping.get(requestURI);// 获取到一个反射的方法 // 反射调用,需要传入对象,需要传入参数,此处无法完成调用,没有把对象缓存起来,也没有参数!!!!改造initHandlerMapping(); // method.invoke() // // 根据uri获取到能够处理当前请求的hanlder(从handlermapping中(list)) Handler handler = getHandler(req); if (handler == null) { resp.getWriter().write("404 not found"); return; } // 参数绑定 // 获取所有参数类型数组,这个数组的长度就是我们最后要传入的args数组的长度 Class<?>[] parameterTypes = handler.getMethod().getParameterTypes(); // 根据上述数组长度创建一个新的数组(参数数组,是要传入反射调用的) Object[] paraValues = new Object[parameterTypes.length]; // 以下就是为了向参数数组中塞值,而且还得保证参数的顺序和方法中形参顺序一致 Map<String, String[]> parameterMap = req.getParameterMap(); // 遍历request中所有参数 (填充除了request,response之外的参数) for (Map.Entry<String, String[]> param : parameterMap.entrySet()) { // name=1&name=2 name [1,2] String value = StringUtils.join(param.getValue(), ","); // 如同 1,2 // 如果参数和方法中的参数匹配上了,填充数据 if (!handler.getParamIndexMapping().containsKey(param.getKey())) { continue; } // 方法形参确实有该参数,找到它的索引位置,对应的把参数值放入paraValues Integer index = handler.getParamIndexMapping().get(param.getKey());//name在第 2 个位置 paraValues[index] = value; // 把前台传递过来的参数值填充到对应的位置去 } int requestIndex = handler.getParamIndexMapping().get(HttpServletRequest.class.getSimpleName()); // 0 paraValues[requestIndex] = req; int responseIndex = handler.getParamIndexMapping().get(HttpServletResponse.class.getSimpleName()); // 1 paraValues[responseIndex] = resp; // 最终调用handler的method属性 try { handler.getMethod().invoke(handler.getController(), paraValues); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } } private Handler getHandler(HttpServletRequest req) { if (handlerMapping.isEmpty()) { return null; } String url = req.getRequestURI(); for (Handler handler : handlerMapping) { Matcher matcher = handler.getPattern().matcher(url); if (!matcher.matches()) { continue; } return handler; } return null; } }
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⼿写MVC框架之 web.xml配置
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>Archetype Created Web Application</display-name> <servlet> <servlet-name>mrdmvc</servlet-name> <servlet-class>com.mrd.edu.mvcframework.servlet.MrdDispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>springmvc.properties</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>mrdmvc</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> </web-app>
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⼿写MVC框架之 最终测试
标签:String,SpringMVC,class,MVC,mrd,import,手写,com,public 来源: https://blog.csdn.net/weixin_36260286/article/details/112000013