SpringMVC 确定pojo值的三步

刺骨的言语ヽ痛彻心扉 2022-10-02 00:31 128阅读 0赞

[2019独角兽企业重金招聘Python工程师标准>>> ][2019_Python_] ![hot3.png][]

1，如果隐含模型中有这个key（标了modelAttribute 注解就是注解指定的value，  
没标就是参数类型的首字母小写）指定的值；如果有将这个值赋值给bindObject  
2，如果是sessionAttribute标注的属性，就从session中拿，拿不到就抛异常  
3，如果都不是，就利用反射创建对象

源码如下：类名HandlerMethodInvoker

private WebDataBinder resolveModelAttribute(String attrName, MethodParameter methodParam,
    			ExtendedModelMap implicitModel, NativeWebRequest webRequest, Object handler) throws Exception {
    
    		// Bind request parameter onto object...
    		String name = attrName;
    		if ("".equals(name)) {
    			name = Conventions.getVariableNameForParameter(methodParam);
    		}
    		Class<?> paramType = methodParam.getParameterType();
    		Object bindObject;
    		if (implicitModel.containsKey(name)) {
    			bindObject = implicitModel.get(name);
    		}
    		else if (this.methodResolver.isSessionAttribute(name, paramType)) {
    			bindObject = this.sessionAttributeStore.retrieveAttribute(webRequest, name);
    			if (bindObject == null) {
    				raiseSessionRequiredException("Session attribute '" + name + "' required - not found in session");
    			}
    		}
    		else {
    			bindObject = BeanUtils.instantiateClass(paramType);
    		}
    		WebDataBinder binder = createBinder(webRequest, bindObject, name);
    		initBinder(handler, name, binder, webRequest);
    		return binder;
    	}

转载于:https://my.oschina.net/u/3574106/blog/3018426

[2019_Python_]: https://my.oschina.net/u/2663968/blog/3061697
[hot3.png]: /images/20220113/0e2fe4d6792f415492ced0e773a2c3d4.png