SSM notes

  spring mvc中的@PathVariable是用来获得请求url中的动态参数的，十分方便，复习下： 

Java代码  收藏代码
@Controller  
public class TestController {  
     @RequestMapping(value="/user/{userId}/roles/{roleId}",method = RequestMethod.GET)  
     public String getLogin(@PathVariable("userId") String userId,  
         @PathVariable("roleId") String roleId){  
         System.out.println("User Id : " + userId);  
         System.out.println("Role Id : " + roleId);  
         return "hello";  
     }  
     @RequestMapping(value="/product/{productId}",method = RequestMethod.GET)  
     public String getProduct(@PathVariable("productId") String productId){  
           System.out.println("Product Id : " + productId);  
           return "hello";  
     }  
     @RequestMapping(value="/javabeat/{regexp1:[a-z-]+}",  
           method = RequestMethod.GET)  
     public String getRegExp(@PathVariable("regexp1") String regexp1){  
           System.out.println("URI Part 1 : " + regexp1);  
           return "hello";  
     }  
}  

required

Whether the parameter is required.

是否需要参数。

Default is true, leading to an exception thrown in case of the parameter missing in the request. Switch this to false if you prefer a null in case of the parameter missing.

默认为true，若请求中没有参数会导致抛出一个异常。若设置为false，若请求中没有参数就会返回null。

Alternatively, provide a defaultValue, which implicitly sets this flag to false.

在required=false时，最好设置一个defaultValue默认值。

@RequestParam(value = "abc",required=false)