如何使用Jackson将数组读入对象的成员变量？

时间：2016-01-11 21:16:53

标签： json parsing jackson

我正在使用Jackson 1.9.5。我在JSON中有这个属性

{"Difficulty Level":["Medium”,”Hard”]}

如何使用Jackson注释将上述内容读入我的字段“difficultyArr”，如下面的对象所示...... 

@JsonIgnoreProperties(ignoreUnknown = true)
public class ThirdPartyQuestionsDto implements Serializable{

    @JsonProperty("Difficulty Level")
    private List<String> difficultyArr = new ArrayList<String>();

    …
     public List<String> getDifficultyArr() {
        return difficultyArr;
    }
    public void setDifficultyArr(List<String> difficultyArr) {
        this.difficultyArr = difficultyArr;
    }

以下是我试图将数据存入我的对象...... 

import org.codehaus.jackson.map.ObjectMapper;
…   
final ObjectMapper mapper = new ObjectMapper();     
final ThirdPartyQuestionsDto itemDto = mapper.readValue(itemJson, ThirdPartyQuestionsDto.class);

但不幸的是我收到以下错误

[ERROR]: org.mainco.subco.myproject.controllers.MyController - Unexpected character ('T' (code 84)): was expecting comma to separate OBJECT entries
at [Source: java.io.StringReader@555b3ec9; line: 1, column: 294]
org.codehaus.jackson.JsonParseException: Unexpected character ('T' (code 84)): was expecting comma to separate OBJECT entries
 at [Source: java.io.StringReader@555b3ec9; line: 1, column: 294]
    at org.codehaus.jackson.JsonParser._constructError(JsonParser.java:1432)
    at org.codehaus.jackson.impl.JsonParserMinimalBase._reportError(JsonParserMinimalBase.java:521)
    at org.codehaus.jackson.impl.JsonParserMinimalBase._reportUnexpectedChar(JsonParserMinimalBase.java:442)
    at org.codehaus.jackson.impl.ReaderBasedParser.nextToken(ReaderBasedParser.java:406)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:690)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2725)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1856)
    at org.mainco.subco.myproject.controllers.MyController.postUploadActivitiesPage(MyController.java:122)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:685)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:919)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:851)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:953)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:855)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:829)
    at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:168)
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:136)
    at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:141)
    at org.mainco.subco.myproject.controllers.MyControllerIT.testUploadLearnosityActivities(MyControllerIT.java:98)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at org.powermock.modules.junit4.rule.PowerMockStatement.evaluate(PowerMockRule.java:63)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:88)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

1 个答案:

答案 0 :(得分：0)

如果您从某处复制粘贴该文本，则它无效JSON。第一个问题是它没有括号括起来。第二个问题是你的一些双引号实际上不是双引号。如果你仔细观察，你会发现它们是不同的。

以下是有效的JSON：

{
    "Difficulty Level": ["Medium", "Hard"]
}
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