如何使用 Apache Daffodil 的 DataProcessor.unparse() 方法来重构原始解析的消息？

Question

我是Apache Daffodil的初学者。

我使用Daffodil Java API成功地将输入文本消息解析为XML字符串，即

Compiler dfdlCompiler = Daffodil.compiler();
dfdlCompiler.setValidateDFDLSchemas(true);
File schemaFile = this.getFileFromResources("EDIFACT-SupplyChain-D03B/EDIFACT-SupplyChain-Messages-D.03B.xsd");
ProcessorFactory processorFactory = dfdlCompiler.compileFile(schemaFile);
DataProcessor dataProcessor = processorFactory.onPath("/");
java.io.File file = getFileFromResources("TestData/ORDERS_D.03B_Interchange.txt");
java.io.FileInputStream fis = new java.io.FileInputStream(file);
InputSourceDataInputStream dis = new InputSourceDataInputStream(fis);
JDOMInfosetOutputter outputter = new JDOMInfosetOutputter();
ParseResult parseResult = dataProcessor.parse(dis, outputter);
Document doc = outputter.getResult().getDocument();
XMLOutputter xo = new XMLOutputter(org.jdom2.output.Format.getPrettyFormat());
String xmlString = xo.outputString(doc);
System.out.println("parsed text... resulting xmlString=" + xmlString);

但是，现在，我不清楚如何使用unparse()方法来重建原始文本消息(似乎缺乏使用Daffodil的Java API来解解析以重建原始消息的示例)。

尝试这个：

SAXBuilder builder = new SAXBuilder();
Document d2 = builder.build(new StringReader(xmlString));
JDOMInfosetInputter inputter = new JDOMInfosetInputter(d2);
WritableByteChannel output = Channels.newChannel(new DataOutputStream(new ByteArrayOutputStream()));
UnparseResult result = dataProcessor.unparse(inputter, output);

如何提取原始消息？ 或者，这种方法不正确吗？

阿帕奇水仙花版本：2.3

Java版本：jdk8+

---

使用这个有点精简的 Java 应用程序进行测试...

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.WritableByteChannel;
import org.jdom2.Document;
import org.jdom2.output.XMLOutputter;
import org.apache.daffodil.japi.Compiler;
import org.apache.daffodil.japi.Daffodil;
import org.apache.daffodil.japi.DataProcessor;
import org.apache.daffodil.japi.ParseResult;
import org.apache.daffodil.japi.ProcessorFactory;
import org.apache.daffodil.japi.UnparseResult;
import org.apache.daffodil.japi.infoset.JDOMInfosetInputter;
import org.apache.daffodil.japi.infoset.JDOMInfosetOutputter;
import org.apache.daffodil.japi.io.InputSourceDataInputStream;
import org.jdom2.input.SAXBuilder;
public class Blah2 {
public static void main(String[] args) throws IOException, Exception {
Blah2 b = new Blah2();
b.process();
}
private void process() throws IOException, Exception {
Compiler dfdlCompiler = Daffodil.compiler();
dfdlCompiler.setValidateDFDLSchemas(true);
File schemaFile = this.getFileFromResources("EDIFACT-SupplyChain-D03B/EDIFACT-SupplyChain-Messages-D.03B.xsd");
ProcessorFactory processorFactory = dfdlCompiler.compileFile(schemaFile);
DataProcessor dataProcessor = processorFactory.onPath("/");
java.io.File file = getFileFromResources("TestData/ORDERS_D.03B_Interchange.txt");
java.io.FileInputStream fis = new java.io.FileInputStream(file);
InputSourceDataInputStream dis = new InputSourceDataInputStream(fis);
JDOMInfosetOutputter outputter = new JDOMInfosetOutputter();
ParseResult parseResult = dataProcessor.parse(dis, outputter);
Document doc = outputter.getResult().getDocument();
XMLOutputter xo = new XMLOutputter(org.jdom2.output.Format.getPrettyFormat());
String xmlString = xo.outputString(doc);
System.out.println("parsed text... resulting xmlString=" + xmlString);
SAXBuilder builder = new SAXBuilder();
Document d2 = builder.build(new StringReader(xmlString));
JDOMInfosetInputter inputter = new JDOMInfosetInputter(d2);
WritableByteChannel output = Channels.newChannel(new DataOutputStream(new ByteArrayOutputStream()));
UnparseResult result = dataProcessor.unparse(inputter, output);
System.out.println("unparsed xml document.. result.toString()=" + String.valueOf(result));        
//how can I obtain the original input text???
}
private File getFileFromResources(String fileName) throws IOException {
URL resource = this.getClass().getClassLoader().getResource(fileName);
return new File(resource.getFile());
}
}   

解析操作的输出如下。

(我仍然不明白我如何完成相反的事情 - 即"未解析")

parsed text... resulting xmlString=<?xml version="1.0" encoding="UTF-8"?>
<D03B:Interchange xmlns:D03B="http://www.ibm.com/dfdl/edi/un/edifact/SupplyChain/D03B">
<UNB>
<S001>
<E0001>UNOA</E0001>
<E0002>4</E0002>
</S001>
<S002>
<E0004>APPLICATION</E0004>
<E0007>1</E0007>
</S002>
<S003>
<E0010>COMPANY</E0010>
<E0007>1</E0007>
</S003>
<S004>
<E0017>20051107</E0017>
<E0019>1159</E0019>
</S004>
<E0020>6002</E0020>
</UNB>
<D03B:Message>
<UNH>
<E0062>SSDD1</E0062>
<S009>
<E0065>ORDERS</E0065>
<E0052>D</E0052>
<E0054>03B</E0054>
<E0051>UN</E0051>
<E0057>EAN008</E0057>
</S009>
</UNH>
<D03B:BadMessage>
<Segment>
<Name>BGM</Name>
<Data>2B3232302B424B4F4439392B39</Data>
</Segment>
<Segment>
<Name>DTM</Name>
<Data>2B3133373A32303035313130373A313032</Data>
</Segment>
<Segment>
<Name>NAD</Name>
<Data>2B42592B353431323334353030303137363A3A39</Data>
</Segment>
<Segment>
<Name>NAD</Name>
<Data>2B53552B343031323334353030303039343A3A39</Data>
</Segment>
<Segment>
<Name>CTA</Name>
<Data>2B4141</Data>
</Segment>
<Segment>
<Name>COM</Name>
<Data>2B7331313A41412A7332313A41412A7333313A4141</Data>
</Segment>
<Segment>
<Name>LIN</Name>
<Data>2B312B312B303736343536393130343A4942</Data>
</Segment>
<Segment>
<Name>QTY</Name>
<Data>2B313A3235</Data>
</Segment>
<Segment>
<Name>FTX</Name>
<Data>2B41464D2B312B2B4C6F7264206F66207468652052696E6773</Data>
</Segment>
<Segment>
<Name>LIN</Name>
<Data>2B322B312B303736343536393039303A4942</Data>
</Segment>
<Segment>
<Name>QTY</Name>
<Data>2B313A3235</Data>
</Segment>
<Segment>
<Name>FTX</Name>
<Data>2B41464D2B312B2B54686520486F62626974</Data>
</Segment>
<Segment>
<Name>LIN</Name>
<Data>2B332B312B313836313030343635363A4942</Data>
</Segment>
<Segment>
<Name>QTY</Name>
<Data>2B313A3136</Data>
</Segment>
<Segment>
<Name>FTX</Name>
<Data>2B41464D2B312B2B5468652053696C6D6172696C6C696F6E</Data>
</Segment>
<Segment>
<Name>LIN</Name>
<Data>2B342B312B303539363030363735363A4942</Data>
</Segment>
<Segment>
<Name>QTY</Name>
<Data>2B313A3130</Data>
</Segment>
<Segment>
<Name>FTX</Name>
<Data>2B41464D2B312B2B546865204368696C6472656E206F6620487572696E</Data>
</Segment>
<Segment>
<Name>UNS</Name>
<Data>2B53</Data>
</Segment>
<Segment>
<Name>CNT</Name>
<Data>2B323A34</Data>
</Segment>
</D03B:BadMessage>
<UNT>
<E0074>22</E0074>
<E0062>SSDD1</E0062>
</UNT>
</D03B:Message>
<UNZ>
<E0036>1</E0036>
<E0020>6002</E0020>
</UNZ>
</D03B:Interchange>
unparsed xml document.. result.toString()=org.apache.daffodil.japi.UnparseResult@2e734540

Answer 1

UnparseResult实际不包含未解析的结果(是的，也许我们可以将其命名为更好的;)。UnparseResult实际上只包含未解析是否成功(通过isError方法)以及失败时的任何诊断。未分析的数据将写入作为参数传入unparse()的WritableByteChannel。

问题是，在您的情况下，您有以下内容来定义该通道：

WritableByteChannel output = Channels.newChannel(new DataOutputStream(new ByteArrayOutputStream()));

因此，您定义的通道写入底层ByteArrayOutputStream，但您无权访问这些字节，因为它未分配给变量。所以你真正要做的是为变量分配一个ByteArrayOutputStream并将其传递给你的新通道，然后在未解析后访问字节数组 - 如下所示：

ByteArrayOutputStream boas = new ByteArrayOutputStream();
WritableByteChannel output = Channels.newChannel(new DataOutputStream(boas));
UnparseResult result = dataProcessor.unparse(inputter, output);
System.out.println(boas.toString());

此外，一些关于Daffodil Java API使用的好资源是我们在这里的Java API测试：

https://github.com/apache/incubator-daffodil/blob/master/daffodil-japi/src/test/java/org/apache/daffodil/example/TestJavaAPI.java

其中包含使用 ByteArrayOutputStream 和 WritableByteChannel 取消解析字节并转换为字符串的示例。