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我有一个 Web 应用程序，其中服务器以 JSON 格式返回任何结果。为了创建 JSON，我使用codehaus Jackson ObjectWriter，版本 1.9.8。

我遇到的问题是，有时在映射中会出现错误，从那时起，所有服务器调用都会导致错误。我无法确定导致错误的原因，但我确实发现了根源。

当异常发生时，服务端返回“(was java.lang.ArrayIndexOutOfBoundsException)(通过引用链：com.onior.modm.restlet.helpers.ServiceResult["success"])”，表示'toJSON中抛出的异常' 被 'toRepresentation' 捕获并映射到 JSON，否则它将返回空。

我只是不知道为什么它有时会失败。我整个早上都可以毫无问题地使用该应用程序，然后突然我会收到此错误。它发生在不同的调用上，但这些调用会在其他时间成功。从我的角度来看，这似乎很随机，但也许有人可以帮助我看到光明？:)

正在映射的服务器结果：

public class ServiceResult<T> {
    private boolean success;
    private T results = null;
    private ModmServiceStatus message = null;

    public ServiceResult() {
    }

    public ServiceResult(T results) {
        this.success = true;
        this.results = results;
    }

    public ServiceResult(boolean success, ModmServiceStatus message) {
        this.success = success;
        this.message = message;
    }

    public ServiceResult(ServiceError error) {
        this(false, new ModmServiceStatus(error));
    }

    public static ServiceResult<ModmServiceStatus> serviceException(
        ServiceError error) {
        return new ServiceResult<ModmServiceStatus>(false,
            new ModmServiceStatus(error.getCode(), error.getDescription()));
    }

    public static ServiceResult<ModmServiceStatus> dbError() {
        return ServiceResult
            .serviceException(ServiceError.GENERIC_DATABASE_ERROR);
    }

    public static ServiceResult<ModmServiceStatus> invalidJson() {
        return ServiceResult
            .serviceException(ServiceError.GENERIC_INVALID_JSON);
    }

    public static ServiceResult<ModmServiceStatus> missingEntity() {
        return ServiceResult                .serviceException(ServiceError.GENERIC_MISSING_OR_INCOMPLETE_ENTITY);
    }

    public static ServiceResult<ModmServiceStatus> entityNotFound() {
        return ServiceResult
            .serviceException(ServiceError.GENERIC_ENTITY_NOT_FOUND);
    }

    public static ServiceResult<ModmServiceStatus> entityDeleted(String entity) {
        return new ServiceResult<ModmServiceStatus>(true,
            new ModmServiceStatus(0, entity + " deleted."));
    }
}

映射：

public class RestUtils {
    private static final boolean PRETTY_PRINT = true;

    public static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
    public static final ObjectWriter OBJECT_WRITER = (PRETTY_PRINT ? OBJECT_MAPPER
        .writerWithDefaultPrettyPrinter() : OBJECT_MAPPER.writer());

    @SuppressWarnings("unchecked")
    public static <T> JacksonRepresentation<T> toJSON(T t) throws IOException {
        JsonRepresentation jsonRepresentation = null;
        JacksonRepresentation<T> jacksonRepresentation = null;
        jsonRepresentation = new JsonRepresentation(
            OBJECT_WRITER.writeValueAsString(t)); // Origin of incidental
                                                    // server error
        jacksonRepresentation = new JacksonRepresentation<T>(
            jsonRepresentation, (Class<T>) t.getClass());
        return jacksonRepresentation;
    }

    public static <T> Representation toRepresentation(ServiceResult<T> ss) {
        Representation representation = null;
        try {
        representation = RestUtils.toJSON(ss);
        } catch (IOException jsonException) {
            jsonException.printStackTrace();
            try {
                jsonException.printStackTrace();
                representation = RestUtils.toJSON(jsonException.getMessage());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return representation;
    }
}

来电：

RestUtils.toRepresentation(new ServiceResult<List<Group>>(groups));

堆栈跟踪的异常：

org.codehaus.jackson.map.JsonMappingException: (was java.lang.ArrayIndexOutOfBoundsException) (through reference chain: com.onior.modm.restlet.helpers.ServiceResult["success"])
    at org.codehaus.jackson.map.JsonMappingException.wrapWithPath(JsonMappingException.java:218)
    at org.codehaus.jackson.map.JsonMappingException.wrapWithPath(JsonMappingException.java:183)
    at org.codehaus.jackson.map.ser.std.SerializerBase.wrapAndThrow(SerializerBase.java:140)
    at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:158)
    at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:112)
    at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:610)
    at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:256)
    at org.codehaus.jackson.map.ObjectWriter._configAndWriteValue(ObjectWriter.java:456)
    at org.codehaus.jackson.map.ObjectWriter.writeValueAsString(ObjectWriter.java:393)
    at com.onior.modm.restlet.helpers.RestUtils.toJSON(RestUtils.java:52)
    at com.onior.modm.restlet.helpers.RestUtils.toRepresentation(RestUtils.java:71)
    at com.onior.modm.restlet.resources.GroupCollectionResource.toJsonRead(GroupCollectionResource.java:191)
    at sun.reflect.GeneratedMethodAccessor143.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.restlet.resource.ServerResource.doHandle(ServerResource.java:506)
    at org.restlet.resource.ServerResource.get(ServerResource.java:707)
    at org.restlet.resource.ServerResource.doHandle(ServerResource.java:589)
    at org.restlet.resource.ServerResource.doNegotiatedHandle(ServerResource.java:649)
    at org.restlet.resource.ServerResource.doConditionalHandle(ServerResource.java:348)
    at org.restlet.resource.ServerResource.handle(ServerResource.java:952)
    at org.restlet.resource.Finder.handle(Finder.java:246)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Router.doHandle(Router.java:431)
    at org.restlet.routing.Router.handle(Router.java:648)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Router.doHandle(Router.java:431)
    at org.restlet.routing.Router.handle(Router.java:648)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:155)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:211)
    at org.restlet.engine.application.ApplicationHelper.handle(ApplicationHelper.java:84)
    at org.restlet.Application.handle(Application.java:381)
    at org.restlet.ext.servlet.ServletAdapter.service(ServletAdapter.java:206)
    at org.restlet.ext.spring.RestletFrameworkServlet.doService(RestletFrameworkServlet.java:124)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ArrayIndexOutOfBoundsException
    at org.codehaus.jackson.impl.WriterBasedGenerator.writeRaw(WriterBasedGenerator.java:577)
    at org.codehaus.jackson.util.DefaultPrettyPrinter$Lf2SpacesIndenter.writeIndentation(DefaultPrettyPrinter.java:279)
    at org.codehaus.jackson.util.DefaultPrettyPrinter.beforeObjectEntries(DefaultPrettyPrinter.java:98)
    at org.codehaus.jackson.impl.WriterBasedGenerator._writePPFieldName(WriterBasedGenerator.java:410)
    at org.codehaus.jackson.impl.WriterBasedGenerator._writeFieldName(WriterBasedGenerator.java:340)
    at org.codehaus.jackson.impl.WriterBasedGenerator.writeFieldName(WriterBasedGenerator.java:217)
    at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:444)
    at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:150)
    ... 58 more
4

1 回答 1

1

得到与 Jackson 1.9.9 完全相同的 ArrayIndexOutOfBoundsException

经过调查，我们的根本原因是多个线程使用共享的 PrettyPrinter。如果您查看 DefaultPrettyPrinter 的 Jackson 代码，您将看到：

/**
 * Number of open levels of nesting. Used to determine amount of
 * indentation to use.
 */
protected int _nesting = 0;

_nesting 最终被用于访问数组。该变量在处理对象时递增和递减。如果多个线程递减它，它最终可能会导致 ArrayIndexOutOfBoundsException 为负数。一旦为负，它就不会再增加，因为异常会在到达一段会增加它的代码之前生成。

在您的代码中，我看到您有一个静态对象编写器。您最终可能会得到一个 DefaultPrettyPrinter 实例。如果您的应用程序可以同时生成 json 对象，给定足够的时间，您将得到异常。

斯蒂芬

于 2013-10-03T21:03:57.670 回答