Java 如何在不使用显式架构文件的情况下在 jaxb 中解组并享受架构验证
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how can i unmarshall in jaxb and enjoy the schema validation without using an explicit schema file
提问by ekeren
I am using jaxb for my application configurations
我在我的应用程序配置中使用 jaxb
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.
我觉得我在做一些非常错误的事情，我正在寻找一种不需要实际文件或此交易的方法。
As you can see in code I:
正如您在代码中看到的，我：
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
1.从我的 JaxbContext（实际上来自我的类注释）创建一个模式到一个文件中 2.设置这个模式文件以便在我解组时允许真正的验证
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(...);
do any of you know how I can validate jaxb without needing to create a schema file that sits in my computer?
你们中有人知道如何验证 jaxb 而无需创建位于我的计算机中的架构文件吗？
Do I need to create a schema for validation, it looks redundant when I get it by JaxbContect.generateSchema ?
我是否需要创建一个用于验证的模式，当我通过 JaxbContect.generateSchema 获取它时它看起来是多余的？
How do you do this?
你怎么做到这一点？
采纳答案by seanf
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.
关于上面ekeren的解决方案，在单个线程中使用PipedOutputStream/PipedInputStream不是一个好主意，以免溢出缓冲区并导致死锁。ByteArrayOutputStream/ByteArrayInputStream 有效，但如果您的 JAXB 类生成多个模式（在不同的命名空间中），您需要多个 StreamSource。
I ended up with this:
我结束了这个：
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
回答by Jason Day
I believe you just need to set a ValidationEventHandleron your unmarshaller. Something like this:
我相信你只需要ValidationEventHandler在你的解组器上设置一个。像这样的东西：
public class JAXBValidator extends ValidationEventCollector {
@Override
public boolean handleEvent(ValidationEvent event) {
if (event.getSeverity() == event.ERROR ||
event.getSeverity() == event.FATAL_ERROR)
{
ValidationEventLocator locator = event.getLocator();
// change RuntimeException to something more appropriate
throw new RuntimeException("XML Validation Exception: " +
event.getMessage() + " at row: " + locator.getLineNumber() +
" column: " + locator.getColumnNumber());
}
return true;
}
}
And in your code:
在你的代码中：
Unmarshaller u = m_context.createUnmarshaller();
u.setEventHandler(new JAXBValidator());
u.unmarshal(...);
回答by dolbysurnd
I had the exact issue and found a solution in the Apache Axis 2 source code:
我遇到了确切的问题，并在 Apache Axis 2 源代码中找到了解决方案：
protected List<DOMResult> generateJaxbSchemas(JAXBContext context) throws IOException {
final List<DOMResult> results = new ArrayList<DOMResult>();
context.generateSchema(new SchemaOutputResolver() {
@Override
public Result createOutput(String ns, String file) throws IOException {
DOMResult result = new DOMResult();
result.setSystemId(file);
results.add(result);
return result;
}
});
return results;
}
and after you've acquired your list of DOMResults that represent the schemas, you will need to transform them into DOMSource objects before you can feed them into a schema generator. This second step might look something like this:
在获得代表模式的 DOMResults 列表后，您需要将它们转换为 DOMSource 对象，然后才能将它们提供给模式生成器。第二步可能看起来像这样：
Unmarshaller u = myJAXBContext.createUnmarshaller();
List<DOMSource> dsList = new ArrayList<DOMSource>();
for(DOMResult domresult : myDomList){
dsList.add(new DOMSource(domresult.getNode()));
}
String schemaLang = "http://www.w3.org/2001/XMLSchema";
SchemaFactory sFactory = SchemaFactory.newInstance(schemaLang);
Schema schema = sFactory.newSchema((DOMSource[]) dsList.toArray(new DOMSource[0]));
u.setSchema(schema);
回答by Alexander
If you use maven using jaxb2-maven-plugin can help you. It generates schemas in generate-resources phase.
如果您使用 maven 使用 jaxb2-maven-plugin 可以帮助您。它在生成资源阶段生成模式。
