手写springMvc

.gitignore

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+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

.idea/.gitignore

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+# 默认忽略的文件
+/shelf/
+/workspace.xml
+# 基于编辑器的 HTTP 客户端请求
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/encodings.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding">
+    <file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
+    <file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
+  </component>
+</project>

.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="17" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>

.idea/vcs.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.wtd</groupId>
+    <artifactId>wtd-mvc</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>war</packaging>
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>servlet-api</artifactId>
+            <version>2.3</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+</project>

src/main/java/com/wtd/annotation/WtdAutowiredAnnotation.java

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+package com.wtd.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:47
+ **/
+@Target({ElementType.FIELD})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface WtdAutowiredAnnotation {
+    String value() default "";
+}

src/main/java/com/wtd/annotation/WtdControllerAnnotation.java

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+package com.wtd.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:47
+ **/
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface WtdControllerAnnotation {
+    String value() default "";
+}

src/main/java/com/wtd/annotation/WtdRequestMappingAnnotation.java

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+package com.wtd.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:47
+ **/
+@Target({ElementType.TYPE,ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface WtdRequestMappingAnnotation {
+    String value() default "";
+}

src/main/java/com/wtd/annotation/WtdRequestParamAnnotation.java

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+package com.wtd.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:47
+ **/
+@Target({ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface WtdRequestParamAnnotation {
+    String value() default "";
+}

src/main/java/com/wtd/annotation/WtdServiceAnnotation.java

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+package com.wtd.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:47
+ **/
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface WtdServiceAnnotation {
+    String value() default "";
+}

src/main/java/com/wtd/controller/WtdController.java

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+package com.wtd.controller;
+
+import com.wtd.annotation.WtdAutowiredAnnotation;
+import com.wtd.annotation.WtdControllerAnnotation;
+import com.wtd.annotation.WtdRequestMappingAnnotation;
+import com.wtd.annotation.WtdRequestParamAnnotation;
+import com.wtd.service.WtdService;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:53
+ **/
+@WtdControllerAnnotation
+@WtdRequestMappingAnnotation("/wtd")
+public class WtdController {
+    @WtdAutowiredAnnotation("WtdServiceImpl")
+    private WtdService wtdService;
+
+    public void query(HttpServletRequest request, HttpServletResponse response,
+                      @WtdRequestParamAnnotation("name")String name,
+                      @WtdRequestParamAnnotation("age")String age){
+        try {
+            PrintWriter pw = response.getWriter();
+            String result = wtdService.query(name, age);
+            pw.write(result);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

src/main/java/com/wtd/service/WtdService.java

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+package com.wtd.service;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:53
+ **/
+public interface WtdService {
+    String query(String name,String age);
+}

src/main/java/com/wtd/service/impl/WtdServiceImpl.java

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+package com.wtd.service.impl;
+
+import com.wtd.annotation.WtdServiceAnnotation;
+import com.wtd.service.WtdService;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 16:53
+ **/
+@WtdServiceAnnotation("WtdServiceImpl")
+public class WtdServiceImpl implements WtdService {
+    @Override
+    public String query(String name, String age) {
+        return "name==="+name+"; age==="+age;
+    }
+}

src/main/java/com/wtd/servlet/DispatcherServlet.java

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+package com.wtd.servlet;
+
+import com.wtd.annotation.*;
+import com.wtd.controller.WtdController;
+
+import javax.servlet.ServletConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+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.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.text.Annotation;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * @program: wtd-mvc
+ * @description:
+ * @author: Mr.Wang
+ * @create: 2023-10-28 17:02
+ **/
+public class DispatcherServlet extends HttpServlet {
+
+    List<String> classNames=new ArrayList<>();
+
+    Map<String,Object> beans=new HashMap<String,Object>();
+    Map<String,Object> handlerMap=new HashMap<String,Object>();
+
+
+    public void init(ServletConfig config){
+        scanPackage("com.wtd");//写到properties
+        doInstance();//根据全类名创建bean
+        doIoc();//根据bean进行依赖注入
+        buildUrlMapping();
+    }
+
+    public void scanPackage(String basePackage){
+        URL url=this.getClass().getClassLoader().getResource("/"+basePackage.replaceAll("\\.","/"));
+        String fileStr=url.getFile();
+        File file=new File(fileStr);
+
+        String[] filesStr = file.list();
+
+        for (String path : filesStr) {
+            File filePath=new File(fileStr+path);
+            if(filePath.isDirectory()){
+                scanPackage(basePackage+"."+path);
+            }else{
+                classNames.add(basePackage+"."+filePath.getName());
+            }
+        }
+    }
+    //根据扫描出来的全类名 进行实例化
+    private void doInstance(){
+        if(classNames.size()<0){
+            System.out.println("扫描失败");
+            return;
+        }
+        //遍历list里面所有的class类
+        for (String className : classNames) {
+            String cn = className.replace(".class", "");
+            try {
+                Class<?> clazz = Class.forName(cn);
+                if(clazz.isAnnotationPresent(WtdControllerAnnotation.class)){
+                    Object instance = clazz.newInstance();
+                    WtdRequestMappingAnnotation requestMappingAnnotation = clazz.getAnnotation(WtdRequestMappingAnnotation.class);
+                    String rmValue=requestMappingAnnotation.value();
+                    beans.put(rmValue,instance);
+                }else if(clazz.isAnnotationPresent(WtdServiceAnnotation.class)){
+                    WtdServiceAnnotation service=clazz.getAnnotation(WtdServiceAnnotation.class);
+                    Object instance=clazz.newInstance();
+                    beans.put(service.value(),instance);
+                }else {
+                    continue;
+                }
+            } catch (ClassNotFoundException e) {
+                e.printStackTrace();
+            }catch (InstantiationException e) {
+                e.printStackTrace();
+            } catch (IllegalAccessException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+    //把service注入到controller
+    public void doIoc(){
+        if(!(beans.entrySet().size() > 0)){
+            System.out.println("没有一个实例类");
+        }
+        for (Map.Entry<String,Object> entry:beans.entrySet()){
+            Object instance=entry.getValue();
+            Class<?> clazz = instance.getClass();
+            if(clazz.isAnnotationPresent(WtdControllerAnnotation.class)){
+                Field[] fields = clazz.getDeclaredFields();
+                for (Field field : fields) {
+                    if(field.isAnnotationPresent(WtdAutowiredAnnotation.class)){
+                        WtdAutowiredAnnotation auto=field.getAnnotation(WtdAutowiredAnnotation.class);
+                        String key=auto.value();
+                        field.setAccessible(true);
+                        try {
+                            field.set(instance,beans.get(key));
+                        } catch (IllegalAccessException e) {
+                            e.printStackTrace();
+                        }
+                    }else {
+                        continue;
+                    }
+                }
+            }else {
+                continue;
+            }
+
+
+        }
+    }
+    private void buildUrlMapping(){
+        if(!(beans.entrySet().size() > 0)){
+            System.out.println("没有类的实例化");
+            return;
+        }
+        for (Map.Entry<String,Object> entry:beans.entrySet()){
+            Object instance=entry.getValue();
+            Class<?> clazz=instance.getClass();
+            if(clazz.isAnnotationPresent(WtdControllerAnnotation.class)){
+                WtdRequestMappingAnnotation requestMappingAnnotation=clazz.getAnnotation(WtdRequestMappingAnnotation.class);
+                String classPath = requestMappingAnnotation.value();
+                Method[] methods = clazz.getMethods();
+                for (Method method : methods) {
+                    if(method.isAnnotationPresent(WtdRequestMappingAnnotation.class)){
+                        WtdRequestMappingAnnotation methodMapping=method.getAnnotation(WtdRequestMappingAnnotation.class);
+                        String methodPath=methodMapping.value();
+                        handlerMap.put(classPath+methodPath,method);
+                    }else {
+                        continue;
+                    }
+                }
+            }else {
+                continue;
+            }
+        }
+    }
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        this.doPost(req,resp);
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        String uri=req.getRequestURI();
+        String context=req.getContextPath();
+        String path=uri.replace(context,"");
+        Method method=(Method) handlerMap.get(path);
+        //根据key=/wtd到map去拿
+        WtdController instance=(WtdController) beans.get("/"+path.split("/")[1]);
+        Object arg[]=hand(req,resp,method);
+        try {
+            method.invoke(instance,arg);
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        } catch (InvocationTargetException e) {
+            e.printStackTrace();
+        }
+    }
+    private static Object[] hand(HttpServletRequest request,HttpServletResponse response,Method method){
+        Class<?>[] paramClazzs = method.getParameterTypes();
+        Object[] args=new Object[paramClazzs.length];
+        int args_i=0;
+        int index=0;
+        for (Class<?> paramClazz : paramClazzs) {
+            if(ServletRequest.class.isAssignableFrom(paramClazz)){
+                args[args_i++]=request;
+            }
+            if(ServletResponse.class.isAssignableFrom(paramClazz)){
+                args[args_i++]=response;
+            }
+            Annotation[] paramAns= (Annotation[]) method.getParameterAnnotations()[index];
+            if(paramAns.length>0){
+                for (Annotation paramAn : paramAns) {
+                    if(WtdRequestParamAnnotation.class.isAssignableFrom(paramAn.getClass())){
+                        WtdRequestParamAnnotation rp=(WtdRequestParamAnnotation) paramAn;
+                        args[args_i++]=request.getParameter(rp.value());
+                    }
+                }
+            }
+            index++;
+        }
+        return args;
+    }
+}

src/main/webapp/WEB-INF/web.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
+         version="4.0">
+    <display-name>wtd-mvc</display-name>
+    <servlet>
+        <servlet-name>DispatcherServlet</servlet-name>
+        <servlet-class>com.wtd.servlet.DispatcherServlet</servlet-class>
+        <load-on-startup>0</load-on-startup>
+    </servlet>
+    <servlet-mapping>
+        <servlet-name>DispatcherServlet</servlet-name>
+        <url-pattern></url-pattern>
+    </servlet-mapping>
+</web-app>