org.apache.camel.NoTypeConversionAvailableException：没有可用于从类型转换的类型转换器：答案

【问题标题】：org.apache.camel.NoTypeConversionAvailableException: No type converter available to convert from type:org.apache.camel.NoTypeConversionAvailableException：没有可用于从类型转换的类型转换器：
【发布时间】：2018-04-07 16:54:27
【问题描述】：

我首先有一个多部分文件，我想将它发送到骆驼管道并用原始名称保存这个文件。

我的代码：

@Autowired
ProducerTemplate producerTemplate;
...
      producerTemplate.sendBody("seda:rest_upload", multipartFile);

另一方面，我有：

from("seda:rest_upload").convertBodyTo(File.class).to("file://rest_files");

我也尝试注册转换器：

@Converter
public class MultiPartFileToFileConvertor {
    @Converter
    public static File toFile(MultipartFile multipartFile) throws IOException {
        File convFile = new File(multipartFile.getOriginalFilename());
        multipartFile.transferTo(convFile);
        return convFile;
    }
}

当我执行我的代码时，我看到以下堆栈跟踪：

Message History
---------------------------------------------------------------------------------------------------------------------------------------
RouteId              ProcessorId          Processor                                                                        Elapsed (ms)
[route2            ] [route2            ] [seda://rest_upload                                                            ] [         3]
[route2            ] [convertBodyTo1    ] [convertBodyTo[java.io.File]                                                   ] [         2]

Stacktrace
---------------------------------------------------------------------------------------------------------------------------------------

org.apache.camel.InvalidPayloadException: No body available of type: java.io.File but has value: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7 of type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile on: Message[ID-ntkachev-1509013331141-0-13]. Caused by: No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7. Exchange[ID-ntkachev-1509013331141-0-14]. Caused by: [org.apache.camel.NoTypeConversionAvailableException - No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7]
    at org.apache.camel.impl.MessageSupport.getMandatoryBody(MessageSupport.java:113) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.ConvertBodyProcessor.process(ConvertBodyProcessor.java:91) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:548) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:201) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:138) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:101) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:201) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.component.seda.SedaConsumer.sendToConsumers(SedaConsumer.java:298) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.component.seda.SedaConsumer.doRun(SedaConsumer.java:210) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.component.seda.SedaConsumer.run(SedaConsumer.java:155) [camel-core-2.20.0.jar:2.20.0]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_111]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_111]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_111]
Caused by: org.apache.camel.NoTypeConversionAvailableException: No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7
    at org.apache.camel.impl.converter.BaseTypeConverterRegistry.mandatoryConvertTo(BaseTypeConverterRegistry.java:206) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.impl.MessageSupport.getMandatoryBody(MessageSupport.java:111) ~[camel-core-2.20.0.jar:2.20.0]
    ... 12 common frames omitted

2017-10-26 13:30:58.447  WARN 19608 --- [a://rest_upload] o.a.camel.component.seda.SedaConsumer    : Error processing exchange. Exchange[]. Caused by: [org.apache.camel.InvalidPayloadException - No body available of type: java.io.File but has value: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7 of type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile on: Message[ID-ntkachev-1509013331141-0-13]. Caused by: No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7. Exchange[ID-ntkachev-1509013331141-0-14]. Caused by: [org.apache.camel.NoTypeConversionAvailableException - No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7]]

org.apache.camel.InvalidPayloadException: No body available of type: java.io.File but has value: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7 of type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile on: Message[ID-ntkachev-1509013331141-0-13]. Caused by: No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7. Exchange[ID-ntkachev-1509013331141-0-14]. Caused by: [org.apache.camel.NoTypeConversionAvailableException - No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7]
    at org.apache.camel.impl.MessageSupport.getMandatoryBody(MessageSupport.java:113) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.ConvertBodyProcessor.process(ConvertBodyProcessor.java:91) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:548) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:201) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:138) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:101) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:201) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.component.seda.SedaConsumer.sendToConsumers(SedaConsumer.java:298) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.component.seda.SedaConsumer.doRun(SedaConsumer.java:210) [camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.component.seda.SedaConsumer.run(SedaConsumer.java:155) [camel-core-2.20.0.jar:2.20.0]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_111]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_111]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_111]
Caused by: org.apache.camel.NoTypeConversionAvailableException: No type converter available to convert from type: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile to the required type: java.io.File with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@24c9ecc7
    at org.apache.camel.impl.converter.BaseTypeConverterRegistry.mandatoryConvertTo(BaseTypeConverterRegistry.java:206) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.impl.MessageSupport.getMandatoryBody(MessageSupport.java:111) ~[camel-core-2.20.0.jar:2.20.0]
    ... 12 common frames omitted

如何解决这个问题？

【问题讨论】：

如果您不转换为文件类型？直接发送即可保存？
是否建议在调用 sendBody 之前创建文件并发送？
我的意思是从：from("seda:rest_upload").convertBodyTo(File.class).to("file://rest_files"); to from("seda:rest_upload").to("file://rest_files");
org.apache.camel.NoTypeConversionAvailableException：没有可用于从类型转换的类型转换器：org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.StandardMultipartFile 到所需的类型：java.io.InputStream with value org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@9c5312b
是的，但是您不能将多部分转换为字节格式并将字节放在交换中吗？那么你不应该得到类型转换错误

标签： java spring type-conversion apache-camel spring-camel

【解决方案1】：

使用 SpringBoot 的类型转换器示例，将使用 Camel 2.23.0 或更高版本自动拾取。

@Component
public class MyPackageTypeConverter implements TypeConverters {

  private final ObjectMapper mapper;

  @Autowired
  public MyPackageTypeConverter(ObjectMapper mapper) {
    this.mapper = mapper;
  }

  @Converter
  public byte[] myPackageToByteArray(MyPackage source) {
    try {
      return mapper.writeValueAsBytes(source);
    } catch (JsonProcessingException e) {
      throw new RuntimeException(e);
    }
  }

  @Converter
  public MyPackage byteArrayToMyPackage(byte[] source) {
    try {
      return mapper.readValue(source, MyPackage.class);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }

}

【讨论】：

【解决方案2】：

您必须在 META-INF 目录中添加名为 TypeConverter 的服务发现文件。

src\main\resources\META-INF\services\org\apache\camel\TypeConverter

此文件包含 @Converter 类。

例如

mypackage.MultiPartFileToFileConvertor

另请参阅 Camel 在 Github https://github.com/camelinaction/camelinaction2/tree/b6a43abf9e0d4ec4e3753ebd735bb3448f98194b/chapter3/converter 中的操作 2 中的示例。

本书第 3.6 章详细解释了自定义转换器的发现和加载如何工作。

【讨论】：

是服务提供接口吗？
我不明白你的评论。您是否在资源中添加了文件？
用这个github.com/apache/camel/blob/master/camel-core/src/main/java/…来自动扫描和加载转换器
@gstackoverflow 对此有任何反馈吗？
源移至github.com/Talend/apache-camel/blob/master/camel-core/src/main/… 尽管阅读文档似乎就足够了