模拟SpringMVC简单实现注解@RequestMapping

2最近一直在研究SpringMVC，根据自己的理解，模拟SpringMVC，简单实现注解@RequestMapping

RequestMapping.java注解类

import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.METHOD)@Retention(RetentionPolicy.RUNTIME)public @interface RequestMapping {    public String value() default "";}

Controller控制层

public class Controller {    @RequestMapping(value="getinfo")    public String getInfo(String username, String password) {        System.out.println("execute getInfo");        System.out.println("username = " + username);        System.out.println("password = " + password);        return "";    }    @RequestMapping(value="getinfo2")    public String getInfo2(String username, String randomArg) {        System.out.println("execute getInfo2");        System.out.println("username = " + username);        System.out.println("randomArg = " + randomArg);        return "";    }    public String getInfo3() {        System.out.println("execute getInfo3");        return "";    }}

SpringRequestMapping.java模拟实现类

import java.lang.reflect.Method;import java.util.ArrayList;import java.util.HashMap;import java.util.Set;import org.springframework.core.LocalVariableTableParameterNameDiscoverer;public class SpringRequestMapping {    private static HashMap<String, Method> uriMethodMap = new HashMap<String, Method>();    /**     * 扫描含有RequestMapping注解的方法，并将uri和对应的方法存储起来     * @param clazz     */    private static void scanRequestMappings(Class<?> clazz) {        Method[] methods = clazz.getDeclaredMethods();        for(Method method : methods) {            if (method.isAnnotationPresent(RequestMapping.class)) {                RequestMapping rm = method.getAnnotation(RequestMapping.class);                uriMethodMap.put(rm.value(), method);            }        }    }    /**     * Spring利用类LocalVariableTableParameterNameDiscoverer得到方法参数名，并将相应的参数值注入到RequestMapping的方法中     * @param method     * @param formParams     * @return      */    public static Object[] getParamsToBePassed(Method method, HashMap<String, Object> formParams) {        LocalVariableTableParameterNameDiscoverer discover = new LocalVariableTableParameterNameDiscoverer();        String[] methodParams = discover.getParameterNames(method);        ArrayList<Object> paramsToBePassed = new ArrayList<Object>();        for (String methodParam : methodParams) {            Set<String> formParamKeys = formParams.keySet();            //和表单里匹配的参数则相应设置值，不匹配的参数将默认设置为空值            if(formParamKeys.contains(methodParam)) {                paramsToBePassed.add(formParams.get(methodParam));            }else {                paramsToBePassed.add(null);            }        }        return paramsToBePassed.toArray();    }    /**     * ，将Form表单的参数注入方法中。根据uri执行对应的处理方法     * @param clazz     * @param uri     * @param formParams     */    public static void executeRequest(Class<?> clazz, String uri, HashMap<String, Object> formParams) {        Method method = uriMethodMap.get(uri);        Object[] paramsToBePassed = getParamsToBePassed(method, formParams);        try {            method.invoke(clazz.newInstance(), paramsToBePassed);        } catch (Exception e) {        }    }}

测试类

import java.util.HashMap;public class SpringRequestMappingTest {    public static void main(String[] args) {        SpringRequestMapping srm = new SpringRequestMapping();        srm.scanRequestMappings(Controller.class);        //模拟前端表单的参数        HashMap<String, Object> formParams = new HashMap<String, Object>();        formParams.put("username", "admin");        formParams.put("password", "123456");        srm.executeRequest(Controller.class, "getinfo", formParams);        srm.executeRequest(Controller.class, "getinfo2", formParams);    }}

控制台输出结果

execute getInfo
username = admin
password = 123456
execute getInfo2
username = admin
password = null（不匹配的参数将默认设置为空值）