Spring中WebDataBinder使用详解

2019-11-26 11:54:57

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Spring MVC Validator @InitBinder and WebDataBinder;Validator是一个用来我们自定义验证的sping接口,WebDataBinder 绑定你的自定义参数,你直接在你的控制器类中通过@InitBinder 注解的方式配置 Web 数据绑定.registerCustomEditor()是一个属性编辑器,比如自定义的日期编辑它绑定web请求参数到JavaBean的属性;

下面一个例子,我们创建一个JavaBean(username, password, email and date of birth of a user),我们创建两个自定义的验证类.第一个,我们验证用户名和密码.第二个,验证邮箱,

在Eclipse中Demo的结构

Validator 是一个有两个方法的接口;

boolean supports(Class<?> clazz) : 检验参数是否验证成功的实例类;

void validate(Object target, Errors errors) : 如果 supports() 方法返回真, target object 合法. Errors.rejectValue() 方法用一个字段名注册错误信息;

UserValidator.java

package com.concretepage.validators;import org.springframework.stereotype.Component;import org.springframework.validation.Errors;import org.springframework.validation.ValidationUtils;import org.springframework.validation.Validator;import com.concretepage.User;@Componentpublic class UserValidator implements Validator {  @Override  public boolean supports(Class<?> clazz) {    return User.class.isAssignableFrom(clazz);  }  @Override  public void validate(Object target, Errors errors) {    User user = (User)target;    ValidationUtils.rejectIfEmptyOrWhitespace(errors, "name", "","Username is empty");    ValidationUtils.rejectIfEmptyOrWhitespace(errors, "password", "", "Password is empty");    if (user.getName().length()<5) {      errors.rejectValue("name","", "Username length is less than 5");    }  }}

EmailValidator.java

package com.concretepage.validators;import org.springframework.stereotype.Component;import org.springframework.validation.Errors;import org.springframework.validation.ValidationUtils;import org.springframework.validation.Validator;import com.concretepage.User;@Componentpublic class EmailValidator implements Validator {  @Override  public boolean supports(Class<?> clazz) {    return User.class.isAssignableFrom(clazz);  }  @Override  public void validate(Object target, Errors errors) {    User user = (User)target;    ValidationUtils.rejectIfEmptyOrWhitespace(errors, "email", "","Email is empty");    if (!user.getEmail().contains("@")) {      errors.rejectValue("email","", "Email is not valid.");    }  }}

User.java

package com.concretepage;import java.util.Date;public class User {  private String name;  private String password;  private String email;  private Date dob;  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public String getPassword() {    return password;  }  public void setPassword(String password) {    this.password = password;  }  public String getEmail() {    return email;  }  public void setEmail(String email) {    this.email = email;  }  public Date getDob() {    return dob;  }  public void setDob(Date dob) {    this.dob = dob;  }}

MyWorldController

package com.concretepage;import java.text.SimpleDateFormat;import java.util.Date;import javax.validation.Valid;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.propertyeditors.CustomDateEditor;import org.springframework.stereotype.Controller;import org.springframework.ui.ModelMap;import org.springframework.validation.BindingResult;import org.springframework.web.bind.WebDataBinder;import org.springframework.web.bind.annotation.InitBinder;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.servlet.ModelAndView;import com.concretepage.validators.EmailValidator;import com.concretepage.validators.UserValidator;@Controller@RequestMapping("/myworld")public class MyWorldController {  @Autowired  private UserValidator userValidator;  @Autowired  private EmailValidator emailValidator;  @RequestMapping(value="signup", method = RequestMethod.GET)  public ModelAndView user(){    return new ModelAndView("user","user",new User());  }  @InitBinder  public void dataBinding(WebDataBinder binder) {    binder.addValidators(userValidator, emailValidator);    SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");    dateFormat.setLenient(false);    binder.registerCustomEditor(Date.class, "dob", new CustomDateEditor(dateFormat, true));  }    @RequestMapping(value="save", method = RequestMethod.POST)  public String createUser(@ModelAttribute("user") @Valid User user,BindingResult result, ModelMap model) {    if(result.hasErrors()) {      return "user";    }    System.out.println("Name:"+ user.getName());    System.out.println("Email:"+ user.getEmail());    System.out.println("Date of Birth:"+ user.getDob());    model.addAttribute("msg", "Welcome to My World!");    return "success";  }  }

Form页面表单

<form:form action="save" method="post" commandName="user">  <tr> <td>User Name:</td> <td><form:input path="name"/> </td>      <td> <form:errors path="name" cssStyle="color: red;"/></td> </tr>  <tr> <td> Password :</td> <td><form:input path="password"/> </td>      <td> <form:errors path="password" cssStyle="color: red;"/> </td> </tr>  <tr> <td> Email :</td> <td><form:input path="email"/> </td>      <td> <form:errors path="email" cssStyle="color: red;"/> </td> </tr>  <tr> <td> Date of Birth :</td> <td><form:input path="dob"/> </td>      <td> <form:errors path="dob" cssStyle="color: red;"/> </td> </tr>       <tr> <td colspan=3>  <input type="submit"> </td> </form:form>

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