fastjson JSON字符串反序列化时，子对象的创建根据构造函数进行创建，而非字段类型Map，而出现反直觉的情况

4bbkushb  于 2021-11-27  发布在  Java
关注(0)|答案(2)|浏览(201)

复现描述

反序列化的目标对象的子对象

@Data
public class PageMessage {
    @ApiModelProperty("UUID唯一码")
    private String key = UUID.randomUUID().toString();
    @ApiModelProperty("Message信息")
    private String content;
    @ApiModelProperty("Message持续时间")
    private double duration;
    @ApiModelProperty("Message样式等级")
    private String pageMessageLevel;

    public PageMessage(String content, double duration, Enum<PageMessageLevel> pageMessageLevel) {
        this.content = content;
        this.duration = duration;
        this.pageMessageLevel = pageMessageLevel.toString();
    }
}

反序列化的JSON字符串

{
        "msg":"添加成功",
	"code":"20000",
	"data":{
		"marketPrice":99.88,
		"introduce":"这是一个测试商品",
		"tagPrice":199.00,
		"isNew":true,
		"productName":"测试商品",
		"content":"这是一段测试商品",
		"castPrice":30,
		"isShow":true,
		"isEnable":true,
		"uom":"件",
		"belongUserId":8116357002098466816,
		"modifyTime":"2021-08-25T15:51:59.617451",
		"createTime":"2021-08-25T15:51:59.617451",
		"id":8118778803791175680
	},
	"success":true,
	"pageMessage":{
		"duration":3.0,
		"key":"19cc20a4-f77d-4ed8-ab95-659000ef5390",
		"content":"添加成功",
		"pageMessageLevel":"error"
	}
}

反序列化主要代码

public static class ResultProduct extends Result<WssProduct> { }

Result<WssProduct> result = JSON.parseObject(jsonString, ResultProduct.class);

报错

com.alibaba.fastjson.JSONException: syntax error, expect {, actual string, pos 479, fieldName pageMessageLevel, fastjson-version 1.2.76

	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:506)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:291)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:287)
	at com.alibaba.fastjson.parser.deserializer.DefaultFieldDeserializer.parseField(DefaultFieldDeserializer.java:88)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.parseField(JavaBeanDeserializer.java:1278)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:893)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:291)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:287)
	at com.alibaba.fastjson.parser.deserializer.DefaultFieldDeserializer.parseField(DefaultFieldDeserializer.java:88)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.parseField(JavaBeanDeserializer.java:1278)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:893)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.parseRest(JavaBeanDeserializer.java:1624)
	at com.alibaba.fastjson.parser.deserializer.FastjsonASMDeserializer_1_ResultProduct.deserialze(Unknown Source)
	at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:287)
	at com.alibaba.fastjson.parser.DefaultJSONParser.parseObject(DefaultJSONParser.java:705)
	at com.alibaba.fastjson.JSON.parseObject(JSON.java:394)
	at com.alibaba.fastjson.JSON.parseObject(JSON.java:298)
	at com.alibaba.fastjson.JSON.parseObject(JSON.java:588)
	at com.vicohu.productcenter.controller.ProductControllerTest.lambda$addProduct$6(ProductControllerTest.java:118)
	at org.springframework.test.web.servlet.MockMvc$1.andExpect(MockMvc.java:196)
	at com.vicohu.productcenter.controller.ProductControllerTest.addProduct(ProductControllerTest.java:117)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:210)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:206)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

临时解决方案

通过增加PageMessage的一个构造方法，注解掉原来的构造方法，把Enum的toString放到示例化该类的方法中，就可以正常解析了。

public PageMessage(String content, double duration, String pageMessageLevel) {
        this.content = content;
        this.duration = duration;
        this.pageMessageLevel = pageMessageLevel;
}

问题

个人认为，作为JSON字符串与对象的字段的对应转换，应该是依据字段的类型进行转换，而不是依据构造方法进行转换。因为直观上而言，这应该是值与值的转换，而不应该让JSON字符串这样一个值为主导的类型，参与到创建对象的过程。

fastjson

2条答案

按热度按时间
dvtswwa3

dvtswwa31#

@wenshao

赞(0）分享  回复(0）举报  2021-11-27
jaql4c8m

jaql4c8m2#

你这对象压根没有空构造函数啊，所以这逻辑没错~ 既然只能用你唯一的传参构造函数构造，并且pageMessageLevel已经通过构造函数传进去了，所以自然认为pageMessageLevel是Enum了~

赞(0）分享  回复(0）举报  2021-11-27
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