Springmvc 简明教程
Spring MVC - Error Handling Example
以下示例展示了如何在表单中使用Spring Web MVC框架中的错误处理和验证器。首先,让我们使用Eclipse IDE并按照以下步骤使用Spring Web框架开发一个基于动态表单的Web应用程序。
Step |
Description |
1 |
按照 Spring MVC - Hello World 章节中的说明,使用 com.tutorialspoint 作为包,创建一个名为 HelloWeb 的项目。 |
2 |
在com.tutorialspoint包中创建Java类Student、StudentController和StudentValidator。 |
3 |
在jsp子文件夹中创建视图文件addStudent.jsp、result.jsp。 |
4 |
最后一步是创建源文件和配置文件的内容,然后按如下所述导出应用程序。 |
Student.java
package com.tutorialspoint;
public class Student {
private Integer age;
private String name;
private Integer id;
public void setAge(Integer age) {
this.age = age;
}
public Integer getAge() {
return age;
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getId() {
return id;
}
}
StudentValidator.java
package com.tutorialspoint;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
public class StudentValidator implements Validator {
@Override
public boolean supports(Class<?> clazz) {
return Student.class.isAssignableFrom(clazz);
}
@Override
public void validate(Object target, Errors errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors,
"name", "required.name","Field name is required.");
}
}
StudentController.java
package com.tutorialspoint;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Validator;
import org.springframework.validation.annotation.Validated;
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;
@Controller
public class StudentController {
@Autowired
@Qualifier("studentValidator")
private Validator validator;
@InitBinder
private void initBinder(WebDataBinder binder) {
binder.setValidator(validator);
}
@RequestMapping(value = "/addStudent", method = RequestMethod.GET)
public ModelAndView student() {
return new ModelAndView("addStudent", "command", new Student());
}
@ModelAttribute("student")
public Student createStudentModel() {
return new Student();
}
@RequestMapping(value = "/addStudent", method = RequestMethod.POST)
public String addStudent(@ModelAttribute("student") @Validated Student student,
BindingResult bindingResult, Model model) {
if (bindingResult.hasErrors()) {
return "addStudent";
}
model.addAttribute("name", student.getName());
model.addAttribute("age", student.getAge());
model.addAttribute("id", student.getId());
return "result";
}
}
HelloWeb-servlet.xml
<beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:context = "http://www.springframework.org/schema/context"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:component-scan base-package = "com.tutorialspoint" />
<bean class = "org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name = "prefix" value = "/WEB-INF/jsp/" />
<property name = "suffix" value = ".jsp" />
</bean>
<bean id = "studentValidator" class = "com.tutorialspoint.StudentValidator" />
</beans>
在这里,对于第一个服务方法 student() ,我们在ModelAndView对象中传递了一个空白Studentobject,名称为“command”,因为如果您在JSP文件中使用<form:form>标记,Spring框架将期待一个名为“command”的对象。因此,当调用student()方法时,它将返回 addStudent.jsp 视图。
第二个服务方法 addStudent() 将在 HelloWeb/addStudent URL上的POST方法中被调用。您将根据提交的信息准备您的模型对象。最后,将从服务方法中返回“result”视图,这将导致渲染result.jsp。如果使用验证器生成了错误,那么将返回相同的“addStudent”视图,Spring将自动在视图中从 BindingResult 注入错误消息。
addStudent.jsp
<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
<head>
<title>Spring MVC Form Handling</title>
</head>
<style>
.error {
color: #ff0000;
}
.errorblock {
color: #000;
background-color: #ffEEEE;
border: 3px solid #ff0000;
padding: 8px;
margin: 16px;
}
</style>
<body>
<h2>Student Information</h2>
<form:form method = "POST" action = "/HelloWeb/addStudent" commandName = "student">
<form:errors path = "*" cssClass = "errorblock" element = "div" />
<table>
<tr>
<td><form:label path = "name">Name</form:label></td>
<td><form:input path = "name" /></td>
<td><form:errors path = "name" cssClass = "error" /></td>
</tr>
<tr>
<td><form:label path = "age">Age</form:label></td>
<td><form:input path = "age" /></td>
</tr>
<tr>
<td><form:label path = "id">id</form:label></td>
<td><form:input path = "id" /></td>
</tr>
<tr>
<td colspan = "2">
<input type = "submit" value = "Submit"/>
</td>
</tr>
</table>
</form:form>
</body>
</html>
在这里,我们使用 <form:errors /> 标签和path="*"来呈现错误消息。例如
<form:errors path = "*" cssClass = "errorblock" element = "div" />
它将呈现所有输入验证的错误消息。
我们使用 <form:errors /> 标签和path="name"来呈现name字段的错误消息。例如
<form:errors path = "name" cssClass = "error" />
它将呈现name字段验证的错误消息。
result.jsp
<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
<head>
<title>Spring MVC Form Handling</title>
</head>
<body>
<h2>Submitted Student Information</h2>
<table>
<tr>
<td>Name</td>
<td>${name}</td>
</tr>
<tr>
<td>Age</td>
<td>${age}</td>
</tr>
<tr>
<td>ID</td>
<td>${id}</td>
</tr>
</table>
</body>
</html>
一旦创建完源文件和配置文件,导出您的应用程序。右键单击应用程序,使用 Export → WAR File 选项,并将 HelloWeb.war 文件保存到 Tomcat 的 webapps 文件夹中。
现在,启动 Tomcat 服务器并确保能够使用标准浏览器访问 webapps 文件夹中的其他网页。尝试以下 URL - http://localhost:8080/HelloWeb/addStudent 如果 Spring Web 应用程序一切正常,我们会看到以下屏幕。
提交所需信息后,单击提交按钮提交表单。如果 Spring Web 应用程序一切正常,您应该看到以下屏幕。