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简化版SpringMVC

web.xml

xml version="1.0" encoding="UTF-8"?>

<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

    <display-name>Web Application</display-name>

    <servlet>

       <servlet-name>mvc</servlet-name>

       <servlet-class>com.aop.mvc.action.DispatcherServlet</servlet-class>

       <init-param>

           <param-name>contextConfigLocation</param-name>

           <param-value>application.properties</param-value>

       </init-param>

       <load-on-startup>1</load-on-startup>

    </servlet>

    <servlet-mapping>

       <servlet-name>mvc</servlet-name>

       <url-pattern>/*</url-pattern>

    </servlet-mapping>

</web-app>

pom.xml

<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.aop.demo</groupId>

    <artifactId>SpringAop-Demo</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <packaging>jar</packaging>

    <name>SpringAop-Demo</name>

    <url>http://maven.apache.org</url>

    <properties>

       <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    </properties>

    <dependencies>

       <dependency>

           <groupId>junit</groupId>

           <artifactId>junit</artifactId>

           <version>3.8.1</version>

           <scope>test</scope>

       </dependency>

       <dependency>

           <groupId>javax.servlet</groupId>

           <artifactId>servlet-api</artifactId>

           <version>2.4</version>

           <scope>provided</scope>

       </dependency>

    </dependencies>

    <build>

       <finalName>${artifactId}</finalName>

       <resources>

           <resource>

              <directory>${basedir}/src/main/resources</directory>

              <includes>

                  <include>**/*</include>

              </includes>

           </resource>

           <resource>

              <directory>${basedir}/src/main/java</directory>

              <excludes>

                  <exclude>**/*.java</exclude>

                  <exclude>**/*.class</exclude>

              </excludes>

           </resource>

       </resources>

    </build>

</project>

application.properties

scanPackage=com.aop.mvc

com.aop.mvc.annotaion

import java.lang.annotation.Documented;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

@Target({ ElementType.FIELD })

@Retention(RetentionPolicy.RUNTIME)

@Documented

public @interface AutoWirted {

String value() default "";

}

@Target({ ElementType.TYPE })

@Retention(RetentionPolicy.RUNTIME)

@Documented

public @interface Controller {

String value() default "";

}

@Target({ ElementType.TYPE, ElementType.METHOD })

@Retention(RetentionPolicy.RUNTIME)

@Documented

public @interface RequestMapping {

String value() default "";

}

@Target({ ElementType.PARAMETER })

@Retention(RetentionPolicy.RUNTIME)

@Documented

public @interface RequestParam {

String value() default "";

}

@Target({ ElementType.TYPE })

@Retention(RetentionPolicy.RUNTIME)

@Documented

public @interface Service {

String value() default "";

}

DemoService.java

package com.aop.mvc.servlet.impl;

import com.aop.mvc.annotaion.Service;

import com.aop.mvc.servlet.IDemoService;

@Service

public class DemoService implements IDemoService {

    public String get(String name) {

       return "My name is " + name;

    }

}

package com.aop.mvc.servlet;

public interface IDemoService {

String get(String name);

}

DispatcherServlet.java

package com.aop.mvc.action;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

import java.net.URL;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Properties;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.aop.mvc.annotaion.AutoWirted;

import com.aop.mvc.annotaion.Controller;

import com.aop.mvc.annotaion.RequestMapping;

import com.aop.mvc.annotaion.Service;

public class DispatcherServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    /** 资源文件 */

    private Properties contextConfig = new Properties();

    /** 扫描到的所有类 */

    private List<String> classNames = new ArrayList<String>();

    /** 实例化类集合 */

    private Map<String, Object> ioc = new HashMap<String, Object>();

    /** url ==> 优化:List handlerMapping */

    private Map<String, Method> handlerMapping = new HashMap<String, Method>();

    @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 {

       try {

           // 6.等待请求

           doDispatch(req, resp);

       } catch (Exception e) {

           e.printStackTrace();

       }

    }

    private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {

       String url = req.getRequestURI();

       String contextPath = req.getContextPath();

       url = url.replace(contextPath, "").replaceAll("/+", "/");

       // 判读HandlerMapping中有返回调用, 没有就404

       if (!handlerMapping.containsKey(url)) {

           resp.getWriter().write("404 Not Found!");

           return;

       }

       Method me = handlerMapping.get(url);

       // me.invoke(req.getParameterMap(), ???);

       System.out.println(me);

    }

    @Override

    public void init(ServletConfig config) throws ServletException {

    System.out.println("======================Begin========================");

       // 1.加载配置文件

       doLoadConfig(config.getInitParameter("contextConfigLocation"));

       // 2.扫描到所有的相关类

       doScanner(contextConfig.getProperty("scanPackage"));

       // 3.初始化刚刚扫描到的类

       doInstance();

       // 4.实现依赖注入

       doAutowired();

       // 5.初始化HadlerMapping

       initHandlerMapping();

       System.out.println("=============== Spring is init OK!");

    }

    private void initHandlerMapping() {

       if (ioc.isEmpty())

           return;

       // 对Controller进行处理

       for (Entry<String, Object> entry : ioc.entrySet()) {

           Class clazz = entry.getValue().getClass();

           // 判断有没有加@Controller注解的

           if (!clazz.isAnnotationPresent(Controller.class))

              continue;

           String baseUtl = "";

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

              RequestMapping requestParam = clazz.getAnnotation(RequestMapping.class);

              baseUtl = requestParam.value();

           }

           Method[] method = clazz.getMethods();

           for (Method meth : method) {

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

                  RequestMapping requestParam = meth.getAnnotation(RequestMapping.class);

                  String url = requestParam.value();

                  url = (baseUtl + url);

                  handlerMapping.put(url, meth);

                  System.out.println("Mapped:" + url + "," + method);

              }

           }

       }

    }

    private void doAutowired() {

       if (ioc.isEmpty())

           return;

       for (Entry<String, Object> entry : ioc.entrySet()) {

           Field[] fields = entry.getValue().getClass().getDeclaredFields();

           for (Field field : fields) {

              // 授权, 只要加了Autowired的

              if (!field.isAnnotationPresent(AutoWirted.class))

                  continue;

              AutoWirted autoWirted = field.getAnnotation(AutoWirted.class);

              String beanName = autoWirted.value().trim();

              if ("".equals(beanName)) {

                  beanName = field.getType().getName();

              }

              // 执行强制授权

              field.setAccessible(true);

              // 进行赋值操作

              try {

                  field.set(entry.getValue(), ioc.get(beanName));

              } catch (Exception e) {

                  e.printStackTrace();

                  continue;

              }

           }

       }

    }

    private void doInstance() {

       // 将扫描到的类初始化

       if (classNames.isEmpty())

           return;

       // 通过反射初始化

       try {

           for (String className : classNames) {

              Class clazz = Class.forName(className);

              // 有注解的类初始化

              if (clazz.isAnnotationPresent(Controller.class)) {

                  Object obj = clazz.newInstance();

                  // 初始化后放入ioc容器中

                  // 默认是类名的首字母小写

                  String beanName = lowerFirstCase(clazz.getSimpleName());

                  ioc.put(beanName, obj);

              } else if (clazz.isAnnotationPresent(Service.class)) {

                  // 1.默认首字母小写

                  // 2.如果是接口, 要把他的实现类赋值给它

                  // 3.如果自定义,就优先用自定义的名字

                  Service service = clazz.getAnnotation(Service.class);

                  String beanName = service.value();

                  if ("".equals(beanName.trim())) {

                     // 如果自定义名字为空,取默认值

                     beanName = lowerFirstCase(clazz.getSimpleName());

                  }

                  Object instance = clazz.newInstance();

                  ioc.put(beanName, instance);

                  // 解决子类引用赋值父类的问题

                  Class[] interfaces = clazz.getInterfaces();

                  for (Class i : interfaces) {

                     ioc.put(i.getName(), instance);

                  }

              } else {

                  continue;

              }

           }

       } catch (Exception e) {

           e.printStackTrace();

       }

    }

    private void doScanner(String scanPackage) {

       URL url = this.getClass().getClassLoader().getResource("/" + scanPackage.replaceAll("\\.", "/"));

       File classDir = new File(url.getFile());

       // 递归扫描指定文件下的类

       for (File file : classDir.listFiles()) {

           if (file.isDirectory()) {// 判断是否文件夹

              doScanner(scanPackage + "." + file.getName());

           } else {// 如果不是文件夹

              String className = scanPackage + "." + file.getName().replace(".class", "");

              classNames.add(className);

           }

       }

    }

    private void doLoadConfig(String contextConfigLocation) {

       InputStream is = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation);

       try {

           contextConfig.load(is);

       } catch (IOException e) {

           e.printStackTrace();

       } finally {

           if (null != is) {

              try {

                  is.close();

              } catch (IOException e) {

                  e.printStackTrace();

              }

           }

       }

    }

    /** 自定义首字母小写 */

    private String lowerFirstCase(String str) {

       char[] chars = str.toCharArray();

       chars[0] += 32;

       return String.valueOf(chars);

    }

}

DemoAction.java

package com.aop.mvc.action;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.aop.mvc.annotaion.AutoWirted;

import com.aop.mvc.annotaion.Controller;

import com.aop.mvc.annotaion.RequestMapping;

import com.aop.mvc.annotaion.RequestParam;

import com.aop.mvc.servlet.IDemoService;

/**

 * @Theme 纯手写实现SpringMVC

 * @author http://localhost:8080/SpringAop-Demo/demo/query.json

 */

@Controller

@RequestMapping("/demo")

public class DemoAction {

    @AutoWirted

    private IDemoService demoService;

    @RequestMapping("/query.json")

    public void query(HttpServletRequest req, HttpServletResponse resp, @RequestParam("name") String name) {

       String result = demoService.get(name);

       try {

           resp.getWriter().write(result);

       } catch (Exception e) {

           // TODO: handle exception

       }

    }

    @RequestMapping("/add.json")

    public void add(HttpServletRequest req, HttpServletResponse resp, @RequestParam("a") Integer a, @RequestParam("b") Integer b) {

       try {

           resp.getWriter().write(a + "+" + b + "=" + (a + b));

       } catch (Exception e) {

           // TODO: handle exception

       }

    }

    @RequestMapping("/remove.json")

    public void remove(HttpServletRequest req, HttpServletResponse resp, @RequestParam("id") Integer id) {

       try {

       } catch (Exception e) {

           // TODO: handle exception

       }

    }

}