前面已經說了,spring mvc可以通過@PathVariable可以把url中的值映射到目標方法的參數上,也可以使用@RequestParam進行單個參數的傳遞,如果一次需要傳遞多個參數的話,就需要寫多個相應的註解,那有沒有什麼更簡單方便的方法呢?答案是有的,spring mvc有自動裝箱的功能,可以通過參數的name屬性,給後臺綁定的對象的對應的屬性完成賦值操作,而且還支持級聯操作,即支持嵌套。
1、使用POJO(Plain Old Java Object)進行參數傳值
下面來看一下具體例子,定義一個User對象,一個Address對象:
public class User { private String userName; private String password; private String email; private int age; private Address address; //省略get和set方法以及toString方法 …… }
public class Address { private String province; private String city; //省略get和set方法以及toString方法 }
Controller的定義如下:
/** * spring mvc可以進行自動"裝箱" ,會按照請求參數的name完成和pojo屬性之間的映射綁定, * 自動爲該對象填充屬性值,並且支持級聯屬性 * * @param user * @return */ @RequestMapping("/testPojo") public String testPojo(User user){ System.out.println(user); return "greeting"; }
測試代碼如下,有User對象的屬性,有級聯屬性Address:
<form action="/testPojo/testPojo" method="post"> <p>pojo測試,可以直接傳遞參數綁定到pojo對象上</p> userName:<input type="text" name="userName"/> <br/> password:<input type="text" name="password"/> <br/> email:<input type="text" name="email"/> <br/> age:<input type="text" name="age"/> <br/> province:<input type="text" name="address.province"/> <br/> city:<input type="text" name="address.city"/> <br/> <input type="submit" value="submit" /> </form>
2、使用Servlet原生API進行參數傳值
spring mvc支持使用ServletRequest和ServletResponse等作爲目標方法的參數。spring mvc支持的類型有以下幾種ServletRequest、ServletResponse、HttpSession、Pricipal、Locale、InputStream、OutputStream、Reader、Writer,具體可以參見源碼:
org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter
@Override protected Object resolveStandardArgument(Class<?> parameterType, NativeWebRequest webRequest) throws Exception { HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class); HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class); if (ServletRequest.class.isAssignableFrom(parameterType) || MultipartRequest.class.isAssignableFrom(parameterType)) { Object nativeRequest = webRequest.getNativeRequest(parameterType); if (nativeRequest == null) { throw new IllegalStateException( "Current request is not of type [" + parameterType.getName() + "]: " + request); } return nativeRequest; } else if (ServletResponse.class.isAssignableFrom(parameterType)) { this.responseArgumentUsed = true; Object nativeResponse = webRequest.getNativeResponse(parameterType); if (nativeResponse == null) { throw new IllegalStateException( "Current response is not of type [" + parameterType.getName() + "]: " + response); } return nativeResponse; } else if (HttpSession.class.isAssignableFrom(parameterType)) { return request.getSession(); } else if (Principal.class.isAssignableFrom(parameterType)) { return request.getUserPrincipal(); } else if (Locale.class == parameterType) { return RequestContextUtils.getLocale(request); } else if (InputStream.class.isAssignableFrom(parameterType)) { return request.getInputStream(); } else if (Reader.class.isAssignableFrom(parameterType)) { return request.getReader(); } else if (OutputStream.class.isAssignableFrom(parameterType)) { this.responseArgumentUsed = true; return response.getOutputStream(); } else if (Writer.class.isAssignableFrom(parameterType)) { this.responseArgumentUsed = true; return response.getWriter(); } return super.resolveStandardArgument(parameterType, webRequest); }
項目源代碼:
https://git.oschina.net/acesdream/spring-mvc