CXF中的java格式XML输出？

Question

我知道在使用Marshaller时如何打开格式。但是我正在使用ApacheCXF（JAX-RS）并返回类似return Response.ok(entity).build();的响应

我还没有找到任何设置输出格式的选项。我怎么做

Answer 1

您可以实现一个MessageBodyWriter。这是一种JAX-RS机制，允许您重写对象如何编组为XML

package org.example;

import java.io.*;
import java.lang.annotation.Annotation;
import java.lang.reflect.*;

import javax.ws.rs.*;
import javax.ws.rs.core.*;
import javax.ws.rs.ext.*;
import javax.xml.bind.*;

@Provider
@Produces(MediaType.APPLICATION_XML)
public class FormattingWriter implements MessageBodyWriter<Object>{

    @Context
    protected Providers providers;

    public boolean isWriteable(Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    public void writeTo(Object object, Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType,
        MultivaluedMap<String, Object> httpHeaders,
        OutputStream entityStream) throws IOException,
        WebApplicationException {
        try {
            ContextResolver<JAXBContext> resolver 
                = providers.getContextResolver(JAXBContext.class, mediaType);
            JAXBContext jaxbContext;
            if(null == resolver || null == (jaxbContext = resolver.getContext(type))) {
                jaxbContext = JAXBContext.newInstance(type);
            }
            Marshaller m = jaxbContext.createMarshaller();
            m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            m.marshal(object, entityStream);
        } catch(JAXBException jaxbException) {
            throw new WebApplicationException(jaxbException);
        }
    }

    public long getSize(Object t, Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType) {
        return -1;
    }

}

了解更多信息

下面是一个完整示例的链接，其中MessageBodyWriter被用作JAX-RS服务的一部分

• http://blog.bdoughan.com/2012/03/moxy-as-your-jax-rs-json-provider.html

Answer 2

首先，获取XML格式化输出的方法是在封送器上设置正确的属性（在使用CXF时通常是JAXB，这是可以的，因为JAXB做了一项可信的工作）。也就是说，在某个地方你会有这样的东西：

marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

问题是，您不一定要格式化all输出；它增加了相当多的开销。幸运的是，您已经在生成一个显式的Response，因此我们可以使用它的更多功能：

Marshaller marshaller = JAXBContext.newInstance(entity.getClass()).createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
StringWriter sw = new StringWriter();
marshaller.marshal(entity, sw);

return Response.ok(sw.toString(), MediaType.APPLICATION_XML_TYPE).build();

---

另一种方法在this JIRA issue中提到（它本身是封闭的，但这对您来说不是什么问题）：

The workaround is to register a custom output handler which can check whatever custom query is used to request the optional indentation:

http://svn.apache.org/repos/asf/cxf/trunk/systests/jaxrs/src/test/java/org/apache/cxf/systest/jaxrs/FormatResponseHandler.java

JAXBElementProvider and JSONProvider are driven by the JAXB Marshaller so by default they check a Marshaller.JAXB_FORMATTED_OUTPUT property on the current message.

这导致了如下代码：

public class FormattedJAXBInterceptor extends AbstractPhaseInterceptor<Message> {
    public FormattedJAXBInterceptor() {
        super(Phase.PRE_STREAM);
    }

    public void handleMessage(Message message) {
        message.put(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
    }

    public void handleFault(Message message) {
        message.put(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
    }
}

CXF站点discusses registration of interceptors