springMVC源码学习之获取参数名

1.入口到参数处理调用流程

入口为spring-webmvc-4.3.18.RELEASE.jar中org.springframework.web.servlet.DispatcherServlet.doService(request,respose)

--》doDispatch(request, response)

--》ha.handle

--》org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal()

--》invokeHandlerMethod（）

--》invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);//将parameterNameDiscoverer对象值赋给org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod父类org.springframework.web.method.support.InvocableHandlerMethod.parameterNameDiscoverer对象invocableMethod.parameterNameDiscoverer。

2.取request中参数流程

当处理request时RequestMappingHandlerAdapter.invokeHandlerMethod()调用org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle()调用父类org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest（）调用getMethodArgumentValues（）取到request中的对应参数值

3.初始化parameterNameDiscoverer流程及源码

以下为初始化org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.parameterNameDiscoverer流程

--》 private ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();

--》spring-core-4.3.18.jar org.springframework.core.DefaultParameterNameDiscoverer();

-->spring-core-4.3.18.jar org.springframework.core.PrioritizedParameterNameDiscoverer.addDiscoverer(new org.springframework.core.StandardReflectionParameterNameDiscoverer() extends ParameterNameDiscoverer)

{

　　List<ParameterNameDiscoverer> parameterNameDiscoverers.add(ParameterNameDiscoverer pnd)

}

//-->spring-core-4.3.18.jar org.springframework.core.MethodParameters.initParameterNameDiscovery()

在org.springframework.core.ParameterNameDiscoverer.getParameterNames(Method method)

-->org.springframework.core.StandardReflectionParameterNameDiscoverer.getParameterNames(Method method)

package org.springframework.core;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import org.springframework.lang.UsesJava8;

@UsesJava8
public class StandardReflectionParameterNameDiscoverer
  implements ParameterNameDiscoverer
{
  public String[] getParameterNames(Method method)
  {
    Parameter[] parameters = method.getParameters();//利用java8的新特性来取参数名
    String[] parameterNames = new String[parameters.length];
    for (int i = 0; i < parameters.length; ++i) {
      Parameter param = parameters[i];
      if (!(param.isNamePresent()))
        return null;

      parameterNames[i] = param.getName();
    }
    return parameterNames;
  }

  public String[] getParameterNames(Constructor<?> ctor)
  {
    Parameter[] parameters = ctor.getParameters();
    String[] parameterNames = new String[parameters.length];
    for (int i = 0; i < parameters.length; ++i) {
      Parameter param = parameters[i];
      if (!(param.isNamePresent()))
        return null;

      parameterNames[i] = param.getName();
    }
    return parameterNames;
  }
}