本文介绍SpringMVC的验证(validation),在Convert一文中,我们知道SpringMVC能很方便的将提交的参数转成(convert)自定义的JavaBean,现在加入对JavaBean的验证,比如要求JavaBean的属性number(private Integer number)不允许为null且最大为5,属性date(private Date date)满足时间是未来的(今天以后的日期)。为此,pom.xml中需要添加两个依赖:
<!-- JSR 303 with Hibernate Validator --> <dependency> <groupId>javax.validation</groupId> <artifactId>validation-api</artifactId> <version>1.0.0.GA</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-validator</artifactId> <version>4.1.0.Final</version> </dependency>
javax.validation.validation-api-1.0.0.GA.jar是一个标准,只有接口方法(以javax开头的包一般都是接口包,业界定义的一些标准,比如servlet-api-2.5.jar中的javax.servlet.HttpServletRequest),还有一个是Hibernate提供的实现包org.hibernate.hibernate-validator-4.1.0.Final。
增加一个Controller,ValidationController:
package org.springframework.samples.mvc.validation; import javax.validation.Valid; import org.springframework.stereotype.Controller; import org.springframework.validation.BindingResult; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; @Controller public class ValidationController { // enforcement of constraints on the JavaBean arg require a JSR-303 provider on the classpath @RequestMapping("/validate") public @ResponseBody String validate(@Valid JavaBean bean, BindingResult result) { if (result.hasErrors()) { return "Object has validation errors"; } else { return "No errors"; } } }
和一个JavaBean:
package org.springframework.samples.mvc.validation; import java.util.Date; import javax.validation.constraints.Future; import javax.validation.constraints.Max; import javax.validation.constraints.NotNull; import org.springframework.format.annotation.DateTimeFormat; import org.springframework.format.annotation.DateTimeFormat.ISO; public class JavaBean { @NotNull @Max(5) private Integer number; @NotNull @Future @DateTimeFormat(iso=ISO.DATE) private Date date; public Integer getNumber() { return number; } public void setNumber(Integer number) { this.number = number; } public Date getDate() { return date; } public void setDate(Date date) { this.date = date; } }
@NotNull、@Future就是javax.validation.validation-api-1.0.0.GA.jar中定义的注解,满足之前说到的需求。
ValidationController的validate方法绑定了一个参数BindingResult result,通过这个变量就可以得到具体的验证信息,比如在validate方法中,如果验证不通过(result.hasErrors()),返回给浏览器文本"Object has validation errors"。
1. 访问"http://localhost:8080/web/validate",浏览器显示"Object has validation errors",number和date不能为空;
2. 访问"http://localhost:8080/web/validate?number=1",浏览器显示"Object has validation errors",date不能为空;
3. 访问"http://localhost:8080/web/validate?number=1&date=2012-03-31",浏览器显示"Object has validation errors",非今天以后的日期;
4. 访问"http://localhost:8080/web/validate?number=1&date=2012-04-01",浏览器显示"No errors";
5. 访问"http://localhost:8080/web/validate?number=6&date=2012-04-01",浏览器显示"Object has validation errors",number不能大于5;