注解验证

http://www.iteye.com/topic/165340
http://www.duduwolf.com/wiki/2007/345.html

需要validation-api和hiberante-validation，
spring的验证是基于
JSR-303
的
validation-api
是jsr303的接口，而hiberante-validation是验证接口的实现。

	@RequestMapping("/valid")
	public String valid(@ModelAttribute("vm") [color=red]@Valid[/color] ValidModel vm, BindingResult result) {
		if (result.hasErrors()) {
			return "validResult";
		}

		return "helloworld";
	}

自定义jsr 303格式的annotation

可以参考hibernate validator 4 reference 手册中3.1节

@Target( { METHOD, FIELD, ANNOTATION_TYPE })  
@Retention(RUNTIME)  
@Constraint(validatedBy = FixLengthImpl.class)  
public @interface FixLength {  
  
    int length();  
    String message() default "{net.zhepu.web.valid.fixlength.message}";  
  
    Class<?>[] groups() default {};  
  
    Class<? extends Payload>[] payload() default {};  
}

验证实现类

public class FixLengthImpl implements ConstraintValidator<FixLength, String> {
	private int length;
	@Override
	public boolean isValid(String validStr,
			ConstraintValidatorContext constraintContext) {
		if (validStr.length() != length) {
			return false;
		} else {
			return true;
		}
	}

	@Override
	public void initialize(FixLength fixLen) {
		this.length = fixLen.length();
	}
}