java反射获取方法参数名的几种方式总结

    class A {
        void getUser(String userName, String userId){}
    }
    
    Method method = A.class.getMethod(String.class,String.class);
    Parameter[] parameters = method.getParameters();
    for (Parameter parameter : parameters) {
        String name = parameter.getName();
        System.out.println(name); // 得到的是arg0, arg1 而非 userName、userId
    }

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <!-- 配置编译时将方法参数名保留 -->
                    <compilerArgs>
                        <arg>-parameters</arg>
                    </compilerArgs>
                </configuration>
            </plugin>

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
        <parameters>true</parameters>
    </configuration>
</plugin>

  // 创建参数名发现器
  ParameterNameDiscoverer discoverer = new StandardReflectionParameterNameDiscoverer();

  Method method = A.class.getMethod(String.class,String.class);

  // 获取方法真实参数名.  userName， userId
  String[] parameterNames = discoverer.getParameterNames(method);

  // 创建参数名发现器
  ParameterNameDiscoverer discoverer = new LocalVariableTableParameterNameDiscoverer();

  Method method = A.class.getMethod(String.class,String.class);

  // 获取方法真实参数名.  userName， userId
  String[] parameterNames = discoverer.getParameterNames(method);

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <compilerArgs>
                        <!-- 生成局部变量表 -->
                        <arg>-g:vars</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>

  // 创建参数名发现器
  ParameterNameDiscoverer discoverer = new DefaultParameterNameDiscoverer();

  Method method = A.class.getMethod(String.class,String.class);

  // 获取方法真实参数名.  userName， userId
  String[] parameterNames = discoverer.getParameterNames(method);

// 源码
public class DefaultParameterNameDiscoverer extends PrioritizedParameterNameDiscoverer {

	public DefaultParameterNameDiscoverer() {
		if (!GraalDetector.inImageCode()) {
			if (KotlinDetector.isKotlinReflectPresent()) {
				addDiscoverer(new KotlinReflectionParameterNameDiscoverer());
			}
			addDiscoverer(new StandardReflectionParameterNameDiscoverer()); // 依赖编译参数 -parameters
			addDiscoverer(new LocalVariableTableParameterNameDiscoverer()); //  // 依赖编译参数 -g
		}
	}

}