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SpringMVC 异常处理
下面的示例展示了如何使用 Spring MVC 框架编写一个简单的基于 Web 的应用程序，该框架可以处理其控制器内部引发的一个或多个异常。
利用我们在 第一个 SpringMVC 项目 这篇文章中创建的HelloWeb项目。
以下是 Student.java 文件的内容
Student.javapackage com.jiyik; 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; } }
以下是 SpringException.java 文件的内容
SpringException.javapackage com.jiyik; public class SpringException extends RuntimeException{ private String exceptionMsg; public SpringException(String exceptionMsg) { this.exceptionMsg = exceptionMsg; } public String getExceptionMsg(){ return this.exceptionMsg; } public void setExceptionMsg(String exceptionMsg) { this.exceptionMsg = exceptionMsg; } }
以下是 StudentController.java 文件的内容。 在这里，需要使用 @ExceptionHandler 注释 service 方法，我们可以在其中指定要处理的一个或多个异常。 如果指定了多个异常，则可以使用逗号分隔值。
StudentController.javapackage com.jiyik; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.ExceptionHandler; 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 org.springframework.ui.ModelMap; @Controller public class StudentController { @RequestMapping(value = "/student", method = RequestMethod.GET) public ModelAndView student() { return new ModelAndView("student", "command", new Student()); } @RequestMapping(value = "/addStudent", method = RequestMethod.POST) @ExceptionHandler({SpringException.class}) public String addStudent( @ModelAttribute("HelloWeb")Student student, ModelMap model) { if(student.getName().length() < 5 ){ throw new SpringException("Given name is too short"); } else { model.addAttribute("name", student.getName()); } if( student.getAge() < 10 ){ throw new SpringException("Given age is too low"); } else { model.addAttribute("age", student.getAge()); } model.addAttribute("id", student.getId()); return "result"; } }
以下是Spring Web配置文件web.xml的内容
web.xml<web-app id = "WebApp_ID" version = "2.4" xmlns = "http://java.sun.com/xml/ns/j2ee" xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation = "http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>Spring Exception Handling</display-name> <servlet> <servlet-name>HelloWeb</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>HelloWeb</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app>
以下是另一个 Spring Web 配置文件 HelloWeb-servlet.xml 的内容
HelloWeb-servlet.xml<beans xmlns = "http://www.springframework.org/schema/beans" xmlns:context = "http://www.springframework.org/schema/context" axmlns: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.jiyik" /> <bean class = "org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name = "prefix" value = "/WEB-INF/jsp/" /> <property name = "suffix" value = ".jsp" /> </bean> <bean class = "org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"> <property name = "exceptionMappings"> <props> <prop key = "com.jiyik.SpringException"> ExceptionPage </prop> </props> </property> <property name = "defaultErrorView" value = "error"/> </bean> </beans>
在这里，我们将 ExceptionPage 指定为异常视图，以防 SpringException 发生，如果有任何其他类型的异常，则会发生通用视图错误。
以下是Spring视图文件student.jsp的内容
student.jsp<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%> <html> <head> <title>Spring MVC Exception Handling</title> </head> <body> <h2>Student Information</h2> <form:form method = "POST" action = "/HelloWeb/addStudent"> <table> <tr> <td><form:label path = "name">Name</form:label></td> <td><form:input path = "name" /></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>
以下是Spring视图文件error.jsp的内容
error.jsp<html> <head> <title>Spring Error Page</title> </head> <body> <p>An error occured, please contact webmaster.</p> </body> </html>
以下是 Spring 视图文件 ExceptionPage.jsp 的内容。 在这里，将通过 ${exception} 访问异常实例。
ExceptionPage.jsp<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%> <html> <head> <title>Spring MVC Exception Handling</title> </head> <body> <h2>Spring MVC Exception Handling</h2> <h3>${exception.exceptionMsg}</h3> </body> </html>
以下是Spring视图文件result.jsp的内容
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>
现在启动 Tomcat 服务器并确保您能够使用标准浏览器从 webapps 文件夹访问其他网页。 现在尝试访问 URL http://localhost:8080/HelloWeb/student 。 如果 Spring Web 应用程序一切正常，应该会看到以下结果。
