【Spring】反射动态修改Bean实例的私有属性值

Cannot cast 'org.springframework.http.client.InterceptingClientHttpRequestFactory' to 'org.springframework.http.client.OkHttp3ClientHttpRequestFactory'

由于RestTemplate在自定义初始化时顺序比较早,想在启动后跟进yum或者注解配置修改初始化的值时,直接修改是不能转换成功的,如下:

RestTemplate restTemplate = GlobalContext.getApplicationContext().getBean(RestTemplate.class);
OkHttp3ClientHttpRequestFactory requestFactory = (OkHttp3ClientHttpRequestFactory)  restTemplate.getRequestFactory();
requestFactory.setReadTimeout(event.getRpcTimeOut());

这样直接改是会报错:Cannot cast 'org.springframework.http.client.InterceptingClientHttpRequestFactory' to 'org.springframework.http.client.OkHttp3ClientHttpRequestFactory'

解决方案:通过反射设置可访问,可写

ReflectionUtils.makeAccessible

将字段设置可访问,可写。本质就是调用field.setAccessible(true),让非public修饰的字段,可以操作如protected、private修饰的字段。

	public static void makeAccessible(Field field) {
		if ((!Modifier.isPublic(field.getModifiers()) ||
				!Modifier.isPublic(field.getDeclaringClass().getModifiers()) ||
				Modifier.isFinal(field.getModifiers())) && !field.isAccessible()) {
			field.setAccessible(true);
		}
	}

实例代码:

try {
                    Field field = InterceptingClientHttpRequestFactory.class.getSuperclass().getDeclaredField("requestFactory");
                    ReflectionUtils.makeAccessible(field);
                    OkHttp3ClientHttpRequestFactory okHttp3ClientHttpRequestFactory = (OkHttp3ClientHttpRequestFactory) field.get(factory);
                    okHttp3ClientHttpRequestFactory.setReadTimeout(event.getRpcTimeOut());
                    okHttp3ClientHttpRequestFactory.setWriteTimeout(event.getRpcTimeOut());

} catch (Exception e) {
     System.out.println("ReflectionUtils.makeAccessible error:" + e.getMessage());
}


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