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java - Apache Camel - 从 Rest 读取 Json 然后转换为 Java 对象

转载 作者：行者123 更新时间：2023-11-30 06:51:54 26 4
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目前我的应用可以

  1. 从本地文件系统读取一个json文件
  2. 使用 Jackson 库的 ObjectMapper 转换为 Java 对象

现在，我想把流程改成

  1. 从rest端点读取一个json内容
  2. 记录json内容
  3. 使用 Jackson 库的 ObjectMapper 转换为 Java 对象

但是，我遇到了一个奇怪的问题，交换的 body 在显示后消失了。想知道我缺少什么可能的设置吗？

XML 内容

<camelContext id="admin_sysHttpRec_ctx" xmlns="http://camel.apache.org/schema/spring" trace="false">

    <restConfiguration component="restlet" host="localhost" port="9394"></restConfiguration>

    <rest path="/sys">
        <put uri="/json" id="admin_sysHttpJson_receiver">
            <to uri="direct:sysJson.process"/>
        </put>
    </rest>

    <route id="admin_sysHttpJson_route">
        <from uri="direct:sysJson.process"/>
        <log message="sysHttpJsonManage BODY: ${body}" loggingLevel="INFO" />
        <process ref="sysJsonManage"/>
        <transform>
            <constant>Success!</constant>
        </transform>
    </route>

</camelContext>

处理器

@Override
public void process(Exchange exchange) throws Exception {
    LOG.info("body: " + exchange.getIn().getBody(String.class));

    // Setup jsonFileContext
    //      byte[] body = exchange.getIn().getBody(byte[].class);
    String bodyStr = exchange.getIn().getBody(String.class);
    byte[] body = bodyStr.getBytes();
    LOG.info("body.length: " + body.length);
    LOG.info("(String) body.length: " + exchange.getIn().getBody(String.class).length());

    try {
        ObjectMapper objectMapper = new ObjectMapper();
        JsonFileContext jsonFileContext = objectMapper.readValue(body, JsonFileContext.class);
        exchange.setProperty("jsonFileContext", jsonFileContext);
    } catch (Exception e) {
        exchange.setException(e);
    }
}

http 请求中的原始负载

{
    "direction":"OUT",
    "srcEncoding":"",
    "destEncoding":""
}

结果

20160929 15:53:33.193 [Restlet-4844614] INFO admin_sysHttpJson_route - sysHttpJsonManage BODY: {
    "direction":"OUT",
    "srcEncoding":"",
    "destEncoding":""
}
20160929 15:53:33.193 [Restlet-4844614] INFO com.test.admin.sys.http.SysJsonManage - body: 
20160929 15:53:33.194 [Restlet-4844614] INFO com.test.admin.sys.http.SysJsonManage - body.length: 0
20160929 15:53:33.194 [Restlet-4844614] INFO com.test.admin.sys.http.SysJsonManage - (String) body.length: 0
20160929 15:53:33.355 [Restlet-4844614] ERROR org.apache.camel.processor.DefaultErrorHandler - Failed delivery for (MessageId: ID-XXXXX-61466-1475135595982-0-1 on ExchangeId: ID-XXXXX-61466-1475135595982-0-2). Exhausted after delivery attempt: 1 caught: com.fasterxml.jackson.databind.JsonMappingException: No content to map due to end-of-input
 at [Source: [B@67e6a2; line: 1, column: 1]

Message History
---------------------------------------------------------------------------------------------------------------------------------------
RouteId              ProcessorId          Processor                                                                        Elapsed (ms)
[admin_sysHttpJson_] [admin_sysHttpJson_] [http://localhost:9394/sys/json?restletMethods=PUT                             ] [       181]
[admin_sysHttpJson_] [restBinding1      ] [                                                                              ] [         4]
[admin_sysHttpJson_] [admin_sysHttpJson_] [direct:sysJson.process                                                        ] [       162]
[admin_sysHttpJson_] [log1              ] [log                                                                           ] [         0]
[admin_sysHttpJson_] [process1          ] [ref:sysJsonManage                                                             ] [       160]

Stacktrace
---------------------------------------------------------------------------------------------------------------------------------------
com.fasterxml.jackson.databind.JsonMappingException: No content to map due to end-of-input
 at [Source: [B@67e6a2; line: 1, column: 1]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148)
    at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:3781)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3721)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2819)
    at com.test.admin.sys.http.SysJsonManage.process(SysJsonManage.java:31)
    at org.apache.camel.processor.DelegateSyncProcessor.process(DelegateSyncProcessor.java:63)
    at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77)
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:468)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:190)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:121)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:83)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:190)
    at org.apache.camel.component.direct.DirectProducer.process(DirectProducer.java:62)
    at org.apache.camel.processor.SendProcessor.process(SendProcessor.java:145)
    at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77)
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:468)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:190)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:121)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:83)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:190)
    at org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:109)
    at org.apache.camel.processor.DelegateAsyncProcessor.process(DelegateAsyncProcessor.java:87)
    at org.apache.camel.component.restlet.RestletConsumer$1.handle(RestletConsumer.java:68)
    at org.apache.camel.component.restlet.MethodBasedRouter.handle(MethodBasedRouter.java:54)
    at org.restlet.routing.Filter.doHandle(Filter.java:150)
    at org.restlet.routing.Filter.handle(Filter.java:197)
    at org.restlet.routing.Router.doHandle(Router.java:422)
    at org.restlet.routing.Router.handle(Router.java:639)
    at org.restlet.routing.Filter.doHandle(Filter.java:150)
    at org.restlet.routing.Filter.handle(Filter.java:197)
    at org.restlet.routing.Router.doHandle(Router.java:422)
    at org.restlet.routing.Router.handle(Router.java:639)
    at org.restlet.routing.Filter.doHandle(Filter.java:150)
    at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:140)
    at org.restlet.routing.Filter.handle(Filter.java:197)
    at org.restlet.routing.Filter.doHandle(Filter.java:150)
    at org.restlet.routing.Filter.handle(Filter.java:197)
    at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:202)
    at org.restlet.Component.handle(Component.java:408)
    at org.restlet.Server.handle(Server.java:507)
    at org.restlet.engine.connector.ServerHelper.handle(ServerHelper.java:63)
    at org.restlet.engine.adapter.HttpServerHelper.handle(HttpServerHelper.java:143)
    at org.restlet.engine.connector.HttpServerHelper$1.handle(HttpServerHelper.java:64)
    at com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:79)
    at sun.net.httpserver.AuthFilter.doFilter(AuthFilter.java:83)
    at com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:82)
    at sun.net.httpserver.ServerImpl$Exchange$LinkHandler.handle(ServerImpl.java:675)
    at com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:79)
    at sun.net.httpserver.ServerImpl$Exchange.run(ServerImpl.java:647)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

我使用的Camel版本是2.17.0

最佳答案

错误消息说明了一切:输入消息正文是一个流(例如 InputStream)，只能使用一次。一种解决方案是启用流缓存，全局(对于 Camel 上下文中的所有路由)或每个路由。有关详细信息，请参阅 the official documentation .

XML - 全局配置:

<camelContext streamCache="true">
    ...
</camelContext>

XML - 单一路由:

<route streamCache="true">
    ...
</route>

Java - 全局配置:

context.setStreamCache(true);

Java - 单一路由:

from("...")
.streamCaching()
.to("...");

还值得注意的是，您可以使用 Camel 的 JSON DataFormat，而不是使用处理器手动反序列化您的 JSON 输入。使用 DSL 中的 unmarshall 步骤。

或者更简单，只需在 REST DSL 中配置 bindingMode 来配置 REST 端点为您执行绑定(bind)并输出一个 POJO。 .类似这样的事情应该可以解决问题(我只测试了 Java DSL，希望 XML 语法是正确的):

<restConfiguration component="restlet" host="localhost" port="9394" bindingMode="json" />

<rest path="/sys">
    <put uri="/json" id="admin_sysHttpJson_receiver" type="JsonFileContext.class">
        <to uri="direct:sysJson.process"/>
    </put>
</rest>

在这两种情况下，您的类路径中都需要 camel-jackson 组件。

关于java - Apache Camel - 从 Rest 读取 Json 然后转换为 Java 对象，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39764717/

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