java通过反射+javassist获得方法所有信息(返回值、方法名、参数类型列表、参数列表)

众所周知，使用java的反射无法获得方法参数名列表，只能获得方法参数类型列表，在网上研究了一下，发现有下面两种方式实现：

方案一：使用反射+javassit库

static void javassistGetInfo() throws Exception{
     Class<?> clazz = Class.forName("fanshe.Person");
     ClassPool pool = ClassPool.getDefault();  
     CtClass cc = pool.get(clazz.getName());  
     
     Method[] declaredMethods = clazz.getDeclaredMethods();
     for (Method mt:declaredMethods) {
       String modifier = Modifier.toString(mt.getModifiers());
       Class<?> returnType = mt.getReturnType();
       String name = mt.getName();
       Class<?>[] parameterTypes = mt.getParameterTypes();
       
       System.out.print("\n"+modifier+" "+returnType.getName()+" "+name+" (");
       
       
       //CtMethod[] declaredMethods1 = cc.getDeclaredMethods();
       CtMethod ctm = cc.getDeclaredMethod(name);
       MethodInfo methodInfo = ctm.getMethodInfo();
       CodeAttribute codeAttribute = methodInfo.getCodeAttribute();
       LocalVariableAttribute attribute = (LocalVariableAttribute)codeAttribute.getAttribute(LocalVariableAttribute.tag);
       int pos = Modifier.isStatic(ctm.getModifiers()) ? 0 : 1;
       for (int i=0;i<ctm.getParameterTypes().length;i++) {
         System.out.print(parameterTypes[i]+" "+attribute.variableName(i+pos));
         if (i<ctm.getParameterTypes().length-1) {
           System.out.print(",");
         }
       }
       
       System.out.print(")");
       
       Class<?>[] exceptionTypes = mt.getExceptionTypes();
       if (exceptionTypes.length>0) {
          System.out.print(" throws ");
          int j=0;
          for (Class<?> cl:exceptionTypes) {
            System.out.print(cl.getName());
            if (j<exceptionTypes.length-1) {
              System.out.print(",");
            }
            j++;
          }
        }
     }
     
  }      

方案二：使用spring的LocalVariableTableParameterNameDiscoverer，相比于javassit，这种方式要简单太多，所以推荐使用这种

import java.lang.reflect.Method;  
import org.springframework.core.LocalVariableTableParameterNameDiscoverer;  
  
public class GetParamNames {  
    public static void main(String[] args) {  
        LocalVariableTableParameterNameDiscoverer u =   
            new LocalVariableTableParameterNameDiscoverer();  
        Demo demo = new Demo();  
        Method[] methods = demo.getClass().getDeclaredMethods();  
        String[] params = u.getParameterNames(methods[0]);  
        for (int i = 0; i < params.length; i++) {  
            System.out.println(params[i]);  
        }  
    }  
}