Java RPC中的反射 (Server)

每次根据方法名来反射获取Method的成本太大，所以在bean初始化的时候，就将该服务下interface的方法都放到HashMap里面

用来测试的interface

public interface TestApi {

    List<Integer> listIds();
    long convertId(long id);

}

扫描interface的方法

    private <T> Map<String, Method> initMethodMap(Class<T> clz) {
        Map<String, Method> methodMap = new HashMap<>();
        Method[] methods = clz.getMethods();

        for (Method method : methods) {
            String methodDesc = ReflectUtil.getMethodDesc(method);
            methodMap.put(methodDesc, method);
        }
        return methodMap;
    }

参数desc获取

class ReflectUtil {

    private static final String PARAM_SPLIT = ",";
    private static final String EMPTY_PARAM = "void";

    public static String getMethodParamDesc(Method method) {
        if (method.getParameterTypes() == null || method.getParameterTypes().length == 0) {
            return EMPTY_PARAM;
        }

        StringBuilder builder = new StringBuilder();

        Class<?>[] clzs = method.getParameterTypes();

        for (Class<?> clz : clzs) {
            String className = getName(clz);
            builder.append(className).append(PARAM_SPLIT);
        }

        return builder.substring(0, builder.length() - 1);
    }

    private static String getName(Class<?> clz) {
        if (!clz.isArray()) {
            return clz.getName();
        }

        StringBuilder sb = new StringBuilder();
        sb.append(clz.getName());
        while (clz.isArray()) {
            sb.append("[]");
            clz = clz.getComponentType();
        }

        return sb.toString();
    }

}

注：代码摘自 weibo 的 rpc 框架 motan; 并有部分修改