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）