手写简单的springmvc框架

来源：互联网发布：刷爱奇艺会员软件2016 编辑：程序博客网时间：2024/04/29 11:42

概述：
本示例实现了简单的IOC和依赖注入，实现了 Controller, Service, RequestMapping, Quatifier 等注解。
具体步骤：

在Servlet初始化时递归扫描对应路径下所用的class，存放到packageNames（List）中
遍历List，记录被Controller和Service注解修饰的class，创建其示例并和path做好映射，存放在instanceMap中。
遍历map中被Controller注解修饰的class，获取其内部被RequestMapping注解修饰的方法引用，并且和Controller注解的value + RequestMapping注解的value 做映射存放在handerMap中
遍历instanceMap中bean带有Quatifier 注解的field，读取该注解的value根据这个值并从instanceMap获取到对应的bean，将这个bean设置到对应的field上面
根据requestURI来获取到对应Controller和Method的引用，通过反射来调用这个方法

代码实现：

DispatcherServlet.java

package main.com.servlet;import java.io.File;import java.io.IOException;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 javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import main.com.annotation.Controller;import main.com.annotation.Quatifier;import main.com.annotation.RequestMapping;import main.com.annotation.Service;import main.com.controller.BaseController;/** * Created by wb-tianlihui on 2017/11/3. */@WebServlet(name = "springmvc", urlPatterns = {"/*", "/helloworld"}, loadOnStartup = 1)public class DispatcherServlet extends HttpServlet {    List<String> packageNames = new ArrayList<String>();    // 所有类的实例，key是注解的value,value是所有类的实例    Map<String, Object> instanceMap = new HashMap<String, Object>();    Map<String, Object> handerMap = new HashMap<String, Object>();    /**     * 地柜扫描包下的所有文件     * @param Package     */    private void scanPackageFiles(String Package) {        URL url = this.getClass().getClassLoader().getResource("/" + replaceTo(Package));        // 将所有的.转义获取对应的路径        String pathFile = url.getFile();        File file = new File(pathFile);        String fileList[] = file.list();        for (String path : fileList) {            File eachFile = new File(pathFile + path);            if (eachFile.isDirectory()) {                scanPackageFiles(Package + "." + eachFile.getName());            } else {                packageNames.add(Package + "." + eachFile.getName());            }        }    }    private String replaceTo(String path) {        return path.replaceAll("\\.", "/");    }    /**     * 将扫描包下所有带有@Controller和Service注解的类创建好示例和对应Controller里面的value映射起来     * @param     */    private void filterAndInstance() throws Exception {        if (packageNames.size() <= 0) {            return;        }        for (String className : packageNames) {            Class<?> cName = Class.forName(className.replace(".class", "").trim());            if (cName.isAnnotationPresent(Controller.class)) {                Object instance = cName.newInstance();                Controller controller = cName.getAnnotation(Controller.class);                String key = controller.value();                instanceMap.put(key, instance);            } else if (cName.isAnnotationPresent(Service.class)) {                Object instance = cName.newInstance();                Service service = cName.getAnnotation(Service.class);                String key = service.value();                instanceMap.put(key, instance);            } else {                continue;            }        }    }    /**     * 将完整的path和Method做好映射     * @param     */    private void handerPathAndMethodMap() {        if (instanceMap.size() <= 0) {return;}        for (Map.Entry<String, Object> entry : instanceMap.entrySet()) {            if (entry.getValue().getClass().isAnnotationPresent(Controller.class)) {                Controller controller = entry.getValue().getClass().getAnnotation(Controller.class);                String ctvalue = controller.value();                Method[] methods = entry.getValue().getClass().getMethods();                for (Method method : methods) {                    if (method.isAnnotationPresent(RequestMapping.class)) {                        RequestMapping rm = method.getAnnotation(RequestMapping.class);                        String rmvalue = rm.value();                        handerMap.put("/" + ctvalue + "/" + rmvalue, method);                    } else {                        continue;                    }                }            } else {                continue;            }        }    }    /**     * 将bean中的依赖注入进去     * @param     */    private void myIoc() {        if (instanceMap.isEmpty()){            return;        }        for (Map.Entry<String, Object> entry : instanceMap.entrySet()) {            // 拿到里面的所有属性            Field fields[] = entry.getValue().getClass().getDeclaredFields();            for (Field field : fields) {                // 可访问私有属性                field.setAccessible(true);                if (field.isAnnotationPresent(Quatifier.class)){                    Quatifier quatifier = field.getAnnotation(Quatifier.class);                    String value = quatifier.value();                    field.setAccessible(true);                    try {                        field.set(entry.getValue(), instanceMap.get(value));                    } catch (Exception e) {                        e.printStackTrace();                    }                }else{                    continue;                }            }        }    }    @Override    public void init() throws ServletException {        super.init();        // 包扫描,获取包中的文件        scanPackageFiles("main.com");        try {            filterAndInstance();            handerPathAndMethodMap();            myIoc();        } catch (Exception e) {            e.printStackTrace();        }    }    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        String url = req.getRequestURI();        String context = req.getContextPath();        String path = url.replace(context, "");        Method method = (Method) handerMap.get(path);        BaseController controller = (BaseController) instanceMap.get(path.split("/")[1]);        try {            method.invoke(controller, new Object[] { req, resp});        } catch (Exception e) {            e.printStackTrace();        }    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        super.doPost(req, resp);    }}

注解：

package main.com.annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;/** * Created by wb-tianlihui on 2017/11/3. */@Retention(RetentionPolicy.RUNTIME)@Target({ElementType.TYPE})public @interface Controller {    String value() default "";}package main.com.annotation;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)@Documentedpublic @interface Quatifier {    String value() default "";}package main.com.annotation;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;/** * Created by wb-tianlihui on 2017/11/3. */@Target({ ElementType.METHOD })@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface RequestMapping {    String value() default "";}package main.com.annotation;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;/** * Created by wb-tianlihui on 2017/11/3. */@Target({ ElementType.TYPE })@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface Service {    String value() default "";}

Controller:

package main.com.controller;/** * Created by wb-tianlihui on 2017/11/5. */public class BaseController {}package main.com.controller;import java.io.IOException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import main.com.annotation.Controller;import main.com.annotation.Quatifier;import main.com.annotation.RequestMapping;import main.com.service.MyService;/** * * @author wb-tianlihui * @date 2017/11/5 */@Controller("tianlh")public class MyController extends BaseController {    @Quatifier("myService")    MyService myService;    @RequestMapping("insert")    public String insert(HttpServletRequest request, HttpServletResponse response) throws IOException {        myService.insert(null);        response.setContentType("text/html;charset=utf8");        response.getWriter().println("MyController被调用");        return "";    }}

Service:

package main.com.service;import java.util.Map;/** * Created by wb-tianlihui on 2017/11/5. */public interface MyService {    int insert(Map map);}package main.com.service;import java.util.Map;import main.com.annotation.Service;/** * Created by wb-tianlihui on 2017/11/5. */@Service("myService")public class MyServiceImpl implements MyService {    @Override    public int insert(Map map) {        System.out.println("MyService被调用");        return 0;    }}

目录结构：
这里写图片描述

运行结果：
这里写图片描述

控制台打印：MyService被调用

阅读全文

0 0