2

我的实体类：

import java.util.ArrayList;


public class Test {
    private String name;
    private String description;
    private ArrayList<String> countries;

    public Test() {

    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public ArrayList<String> getCountries() {
        return countries;
    }

    public void setCountries(ArrayList<String> countries) {
        this.countries = countries;
    }
}

我试图发送的 JSON：

{"countries": ["CA", "SG"], "description":"whee", "name": "foo"}

错误：

2345447 [http-bio-8080-exec-1] ERROR freemarker.runtime  - Method public java.lang.String org.apache.commons.lang.exception.NestableRuntimeException.getMessage(int) threw an exception when invoked on net.sf.json.JSONException: Error while setting property=countries type interface java.util.List

Method public java.lang.String org.apache.commons.lang.exception.NestableRuntimeException.getMessage(int) threw an exception when invoked on net.sf.json.JSONException: Error while setting property=countries type interface java.util.List
The problematic instruction:
----------
==> ${msgs[0][0]} [on line 76, column 25 in org/apache/struts2/dispatcher/error.ftl]
----------

Java backtrace for programmers:
----------
freemarker.template.TemplateModelException: Method public java.lang.String org.apache.commons.lang.exception.NestableRuntimeException.getMessage(int) threw an exception when invoked on net.sf.json.JSONException: Error while setting property=countries type interface java.util.List
    at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:130)
    at freemarker.ext.beans.SimpleMethodModel.get(SimpleMethodModel.java:138)
    at freemarker.core.DynamicKeyName.dealWithNumericalKey(DynamicKeyName.java:111)
    at freemarker.core.DynamicKeyName._getAsTemplateModel(DynamicKeyName.java:90)
    at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
    at freemarker.core.Expression.getStringValue(Expression.java:93)
    at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.MixedContent.accept(MixedContent.java:92)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.IfBlock.accept(IfBlock.java:82)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.IfBlock.accept(IfBlock.java:82)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.MixedContent.accept(MixedContent.java:92)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.Environment.process(Environment.java:190)
    at freemarker.template.Template.process(Template.java:237)
    at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:797)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:519)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:851)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:278)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:300)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.NullPointerException
    at freemarker.ext.beans.SimpleMemberModel.unwrapArguments(SimpleMemberModel.java:85)
    at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:106)
    ... 37 more

设置“名称”和“描述”而不尝试传递“国家”工作 - 值已成功映射。

使用以下 XML 也可以：

<com.foo.bar.entity.Test>
<countries>
<string>SG</string>
</countries>
<description>testt</description>
</com.foo.bar.entity.Test>

更新：

如果我将列表更改为字符串 []，它会起作用。我可以忍受这一点，但有人知道是否可以向 Struts/rest-plugin/json-plugin 表明我更喜欢 List 而不是数组？

4

1 回答 1

0

尝试这样做 

private List<String> countries;

List<>当 json 解析器发送一个对象并且你的 var 是类型时，可能会发生错误ArrayList<>

我们现在不知道解析器将设置什么实例类型，所以总是使用接口而不是实现。

于 2012-10-11T03:02:21.457 回答