如何在jaxb中解组并享受模式验证而不使用显式模式文件 [英] how can i unmarshall in jaxb and enjoy the schema validation without using an explicit schema file

问题描述

我正在使用jaxb进行我的应用程序配置

I am using jaxb for my application configurations

我觉得我正在做一些非常歪曲的事情，我正在寻找一种不需要实际文件的方法交易。

I feel like I am doing something really crooked and I am looking for a way to not need an actual file or this transaction.

正如你在代码I中看到的那样：

As you can see in code I:

1.从我的文件中创建一个模式JaxbContext（实际来自我的类​​注释）
2.设置此模式文件以便在我解组时允许真正的验证

1.create a schema into a file from my JaxbContext (from my class annotation actually) 2.set this schema file in order to allow true validation when I unmarshal

JAXBContext context = JAXBContext.newInstance(clazz);
Schema mySchema = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(schemaFile);
jaxbContext.generateSchema(new MySchemaOutputResolver()); // ultimately creates schemaFile   
Unmarshaller u = m_context.createUnmarshaller();
u.setSchema(mySchema);
u.unmarshal(...);

你们中的任何人都知道如何验证jaxb而不需要创建一个位于我的模式文件中计算机？

do any of you know how I can validate jaxb without needing to create a schema file that sits in my computer?

我是否需要创建一个用于验证的模式，当我通过JaxbContect.generateSchema获取它时看起来多余？

Do I need to create a schema for validation, it looks redundant when I get it by JaxbContect.generateSchema ?

你是怎么做到的？

推荐答案

关于上面的ekeren解决方案，使用PipedOutputStream / PipedInputStream不是一个好主意在一个线程中，以免溢出缓冲区并导致死锁。 ByteArrayOutputStream / ByteArrayInputStream可以工作，但如果您的JAXB类生成多个模式（在不同的名称空间中），则需要多个StreamSource。

Regarding ekeren's solution above, it's not a good idea to use PipedOutputStream/PipedInputStream in a single thread, lest you overflow the buffer and cause a deadlock. ByteArrayOutputStream/ByteArrayInputStream works, but if your JAXB classes generate multiple schemas (in different namespaces) you need multiple StreamSources.

我最终得到了这个：

JAXBContext jc = JAXBContext.newInstance(Something.class);
final List<ByteArrayOutputStream> outs = new ArrayList<ByteArrayOutputStream>();
jc.generateSchema(new SchemaOutputResolver(){
    @Override
    public Result createOutput(String namespaceUri, String suggestedFileName) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        outs.add(out);
        StreamResult streamResult = new StreamResult(out);
        streamResult.setSystemId("");
        return streamResult;
    }});
StreamSource[] sources = new StreamSource[outs.size()];
for (int i=0; i<outs.size(); i++) {
    ByteArrayOutputStream out = outs.get(i);
    // to examine schema: System.out.append(new String(out.toByteArray()));
    sources[i] = new StreamSource(new ByteArrayInputStream(out.toByteArray()),"");
}
SchemaFactory sf = SchemaFactory.newInstance( XMLConstants.W3C_XML_SCHEMA_NS_URI );
m.setSchema(sf.newSchema(sources));
m.marshal(docs, new DefaultHandler());  // performs the schema validation

这篇关于如何在jaxb中解组并享受模式验证而不使用显式模式文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！