Spring MVC Controller傳遞枚舉值的實(shí)例

更新時(shí)間：2021年09月22日 10:06:55 作者：bladestone

這篇文章主要介紹了Spring MVC Controller傳遞枚舉值的實(shí)例，具有很好的參考價(jià)值，希望對(duì)大家有所幫助。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教

Spring MVC Controller傳遞枚舉值

功能描述

本文將通過一個(gè)小示例，展示在請(qǐng)求參數(shù)中傳遞枚舉值。

枚舉定義

角色類定義：

public enum RoleEnum {
 EMPLOYEE((short)1, "Employee"), MANAGER((short)2, "Manager");
 
 private Short value;
 private String desc;
 
 private RoleEnum(Short value, String desc) {
  this.value = value;
  this.desc = desc;
 }
 
 public Short value() {
  return value;
 }
 
 public String desc() {
  return desc;
 }
}

定義Controller類

@RestController
@Slf4j
public class HomeController {
 @GetMapping("/home")
 public String getDemo(@RequestParam("role") RoleEnum role) {
  log.info("Role Enum:{}" + role);  
  return role.desc();
 }
}

說明：在這里RoleEnum之內(nèi)作為@RequestParam參數(shù)。

請(qǐng)求示例

Case1: http://localhost:8080/home?role=EMPLOYEE

結(jié)論：正確返回， Employee

Case2: http://localhost:8080/home?role=Employee

報(bào)錯(cuò)，具體信息如下：

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Thu May 14 11:21:32 CST 2020
There was an unexpected error (type=Bad Request, status=400).
Failed to convert value of type 'java.lang.String' to required type 'org.course.data.domain.RoleEnum'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam org.course.data.domain.RoleEnum] for value 'employee'; nested exception is java.lang.IllegalArgumentException: No enum constant org.course.data.domain.RoleEnum.employee
org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'org.course.data.domain.RoleEnum'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam org.course.data.domain.RoleEnum] for value 'employee'; nested exception is java.lang.IllegalArgumentException: No enum constant org.course.data.domain.RoleEnum.employee
   at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:133)
   at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:127)
   at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167)
   at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
   at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:893)
   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:798)
   at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
   at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
   at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
   at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
   at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
   at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:94)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
   at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
   at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
   at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
   at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
   at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
   at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
   at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
   at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
   at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1639)
   at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
   at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
   at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.RequestParam org.course.data.domain.RoleEnum] for value 'employee'; nested exception is java.lang.IllegalArgumentException: No enum constant org.course.data.domain.RoleEnum.employee
   at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:47)
   at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:191)
   at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:129)
   at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:73)
   at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:53)
   at org.springframework.validation.DataBinder.convertIfNecessary(DataBinder.java:693)
   at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:125)
   ... 51 more
Caused by: java.lang.IllegalArgumentException: No enum constant org.course.data.domain.RoleEnum.employee
   at java.lang.Enum.valueOf(Enum.java:238)
   at org.springframework.core.convert.support.StringToEnumConverterFactory$StringToEnum.convert(StringToEnumConverterFactory.java:52)
   at org.springframework.core.convert.support.StringToEnumConverterFactory$StringToEnum.convert(StringToEnumConverterFactory.java:38)
   at org.springframework.core.convert.support.GenericConversionService$ConverterFactoryAdapter.convert(GenericConversionService.java:436)
   at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
   ... 57 more

實(shí)現(xiàn)分析：

final class StringToEnumConverterFactory implements ConverterFactory<String, Enum> {
    StringToEnumConverterFactory() {
    }
    public <T extends Enum> Converter<String, T> getConverter(Class<T> targetType) {
        return new StringToEnumConverterFactory.StringToEnum(ConversionUtils.getEnumType(targetType));
    }
    private class StringToEnum<T extends Enum> implements Converter<String, T> {
        private final Class<T> enumType;
        public StringToEnum(Class<T> enumType) {
            this.enumType = enumType;
        }
        public T convert(String source) {
            return source.isEmpty() ? null : Enum.valueOf(this.enumType, source.trim());
        }
    }
}

底層實(shí)現(xiàn)為將String轉(zhuǎn)換為Enum值的過程。

結(jié)論

基于枚舉可以限定具體值，簡(jiǎn)單易用。但是缺點(diǎn)是在擴(kuò)展enum之時(shí)，無法做法平滑過度升級(jí)，會(huì)吹安短暫的異常情況。

Spring MVC 枚舉傳值問題

今天遇到算是棘手的一個(gè)枚舉的問題，后臺(tái)Controller參數(shù)是一個(gè)對(duì)象，而對(duì)象里面有個(gè)枚舉類型的屬性，死活不能傳值。

最后找到解決方案

實(shí)體對(duì)象：

@Entity
@Table(name="xx_sn")
@SequenceGenerator(name = "sequenceGenerator", sequenceName = "xx_sn_sequence")
public class ShoppTest extends BaseEntity{
	private static final long serialVersionUID = 2756395514949325790L;
	/**
	 * 枚舉
	 * @author Administrator
	 *
	 */
	public enum Type{
		/** 商品 */
		product,
 
		/** 訂單 */
		order,
 
		/** 收款單 */
		payment,
 
		/** 退款單 */
		refunds,
 
		/** 發(fā)貨單 */
		shipping,
 
		/** 退貨單 */
		returns
	}
	@Column(nullable = false, updatable = false, unique = true)
	private Type type;
	
	@Column(nullable = false)
	private String lastValue;
	
	public String getLastValue() {
		return lastValue;
	}
	public void setLastValue(String lastValue) {
		this.lastValue = lastValue;
	}
	
	public Type getType() {
		return type;
	}
	
	public void setType(Type type) {
		this.type = type;
	}

Controller代碼：

 @RequestMapping("/save")
 public String save(ShoppTest st,String tp){
  st.setType(Enum.valueOf(Type.class, tp));
  shoppTestServiceImpl.save(st);
  return "redirect:list.jhtml";
 }

前臺(tái)代碼：

<form id="inputForm" action="save.jhtml" method="post">
<table class="input">
<tr>
<th>
${message("test.lastValue")}:
</th>
<td colspan="2">
<input type="text" name="lastValue" class="text">
</td>
</tr>
<tr>
<th>
<span class="requiredField">*</span>${message("test.type")}:
</th>
<td colspan="2">
<input type="text" name="tp" class="text" maxlength="200" />
</td>
</tr>
</table>
<table class="input">
<tr>
<th> 
</th>
<td>
<input type="submit" class="button" value="${message("admin.common.submit")}" />
<input type="button" class="button" value="${message("admin.common.back")}" οnclick="location.href='list.jhtml'" />
</td>
</tr>
</table>
</form>

因?yàn)閟pringMVC對(duì)于枚舉這種特殊的數(shù)據(jù)類型不能直接進(jìn)行數(shù)據(jù)注入，所以訪問Controller的時(shí)候直接就是400錯(cuò)誤。

所以我這里用String去接收前臺(tái)傳來的枚舉需要的數(shù)據(jù)，也就是“tp”，用到Enum.ValueOf（）;

ValueOf需要兩個(gè)參數(shù)，第一個(gè)參數(shù)類型就是自己定義的枚舉類類型，第二個(gè)參數(shù)是你枚舉里面

定義的字段名字，這個(gè)字段就對(duì)應(yīng)了你枚舉所得到的值。

最終取到值后賦值給對(duì)象里面的枚舉。

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

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