如何在返回多种类型的 XML 的 URL 上使用 Spring RestTemplate 和 JAXB 编组

我需要对返回 a 或 a 且始终状态代码的服务进行 Rest POST。（蹩脚的第三方产品！<job/><exception/>200

我有这样的代码：

Job job = getRestTemplate().postForObject(url, postData, Job.class);

我的应用程序Context.xml看起来像这样：

<bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
    <constructor-arg ref="httpClientFactory"/>

    <property name="messageConverters">
        <list>
            <bean class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
                <property name="marshaller" ref="jaxbMarshaller"/>
                <property name="unmarshaller" ref="jaxbMarshaller"/>
            </bean>
            <bean class="org.springframework.http.converter.FormHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
        </list>
    </property>
</bean>

<bean id="jaxbMarshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
    <property name="classesToBeBound">
        <list>
            <value>domain.fullspec.Job</value>
            <value>domain.fullspec.Exception</value>
        </list>
    </property>
</bean>

当我尝试进行此调用并且服务失败时，我得到：

 Failed to convert value of type 'domain.fullspec.Exception' to required type 'domain.fullspec.Job'

在postForObject（）电话中，我要求一份工作.class没有得到一份工作，它越来越难过。

我想我需要能够做一些事情：

Object o = getRestTemplate().postForObject(url, postData, Object.class);
if (o instanceof Job.class) {
   ...
else if (o instanceof Exception.class) {
}

但这不起作用，因为JAXB抱怨它不知道如何封送到Object.class - 这并不奇怪。

我试图创建编组HttpMessageConverter的子类并覆盖readFromSource（）

protected Object readFromSource（Class clazz， HttpHeaders headers， Source source） {

    Object o = null;
    try {
        o = super.readFromSource(clazz, headers, source);
    } catch (Exception e) {
        try {
            o = super.readFromSource(MyCustomException.class, headers, source);
        } catch (IOException e1) {
            log.info("Failed readFromSource "+e);
        }
    }

    return o;
}

不幸的是，这不起作用，因为在我重试时，源中的基础输入流已关闭。

任何建议都非常感谢收到，

汤姆

更新：我通过获取输入流的副本来使其工作

protected Object readFromSource(Class<?> clazz, HttpHeaders headers, Source source) {
    InputStream is = ((StreamSource) source).getInputStream();

    // Take a copy of the input stream so we can use it for initial JAXB conversion
    // and if that fails, we can try to convert to Exception
    CopyInputStream copyInputStream = new CopyInputStream(is);

    // input stream in source is empty now, so reset using copy
    ((StreamSource) source).setInputStream(copyInputStream.getCopy());

    Object o = null;
    try {
        o = super.readFromSource(clazz, headers, source);
      // we have failed to unmarshal to 'clazz' - assume it is <exception> and unmarshal to MyCustomException

    } catch (Exception e) {
        try {

            // reset input stream using copy
            ((StreamSource) source).setInputStream(copyInputStream.getCopy());
            o = super.readFromSource(MyCustomException.class, headers, source);

        } catch (IOException e1) {
            e1.printStackTrace();  
        }
        e.printStackTrace();
    }
    return o;

}

CopyInputStream取自 http://www.velocityreviews.com/forums/t143479-how-to-make-a-copy-of-inputstream-object.html，我会把它粘贴在这里。

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class CopyInputStream
{
private InputStream _is;
private ByteArrayOutputStream _copy = new ByteArrayOutputStream();

/**
 * 
 */
public CopyInputStream(InputStream is)
{
    _is = is;

    try
    {
        copy();
    }
    catch(IOException ex)
    {
        // do nothing
    }
}

private int copy() throws IOException
{
    int read = 0;
    int chunk = 0;
    byte[] data = new byte[256];

    while(-1 != (chunk = _is.read(data)))
    {
        read += data.length;
        _copy.write(data, 0, chunk);
    }

    return read;
}

public InputStream getCopy()
{
    return (InputStream)new ByteArrayInputStream(_copy.toByteArray());
}
}