问题
I cannot seem to be able to unmarshall a Map properly using XStream.
I have the following code:
Storage class
public class Storage
{
@XStreamAsAttribute
private String basedir;
@XStreamAsAttribute
private Map<String, Repository> repositories = new LinkedHashMap<String, Repository>();
...
}
Repository class
public class Repository
{
@XStreamAsAttribute
private String name;
@XStreamAsAttribute
private String basedir;
@XStreamAsAttribute
private int policy;
@XStreamAsAttribute
private int layout;
@XStreamAsAttribute
private int type;
...
}
ConfigurationParser class
public class ConfigurationParser
{
public Storage parseConfiguration(String xmlFile)
throws FileNotFoundException
{
FileInputStream fis = new FileInputStream(xmlFile);
XStream xstream = new XStream();
xstream.autodetectAnnotations(true);
xstream.alias("storage", Storage.class);
xstream.alias("repositories", Map.class);
xstream.alias("repository", Repository.class);
return (Storage) xstream.fromXML(fis);
}
}
configuration.xml
<storage>
<basedir>storages/storage0</basedir>
<repositories>
<repository>
<name>repository0</name>
<policy>snapshots</policy>
<layout>maven2</layout>
<type>hosted</type>
</repository>
</repositories>
</storage>
Could somebody please give me some hints as to what is wrong. This is the error message:
com.thoughtworks.xstream.converters.ConversionException: name : name
---- Debugging information ----
message : name
cause-exception : com.thoughtworks.xstream.mapper.CannotResolveClassException
cause-message : name
class : java.util.HashMap
required-type : java.util.HashMap
converter-type : com.thoughtworks.xstream.converters.collections.MapConverter
path : /storage/repositories/repository/name
line number : 5
class[1] : org.foo.storage.Storage
converter-type[1] : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
version : null
-------------------------------
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:79)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:355)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:306)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:234)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:134)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1058)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1042)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:922)
at org.foo.configuration.ConfigurationParser.parseConfiguration(ConfigurationParser.java:36)
at org.foo.configuration.ConfigurationParserTest.testParseConfiguration(ConfigurationParserTest.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:74)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:196)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:64)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
Caused by: com.thoughtworks.xstream.mapper.CannotResolveClassException: name
at com.thoughtworks.xstream.mapper.DefaultMapper.realClass(DefaultMapper.java:56)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.DynamicProxyMapper.realClass(DynamicProxyMapper.java:55)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.PackageAliasingMapper.realClass(PackageAliasingMapper.java:88)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.ClassAliasingMapper.realClass(ClassAliasingMapper.java:79)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.ArrayMapper.realClass(ArrayMapper.java:74)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
at com.thoughtworks.xstream.mapper.CachingMapper.realClass(CachingMapper.java:45)
at com.thoughtworks.xstream.core.util.HierarchicalStreams.readClassType(HierarchicalStreams.java:29)
at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.readItem(AbstractCollectionConverter.java:70)
at com.thoughtworks.xstream.converters.collections.MapConverter.putCurrentEntryIntoMap(MapConverter.java:86)
at com.thoughtworks.xstream.converters.collections.MapConverter.populateMap(MapConverter.java:78)
at com.thoughtworks.xstream.converters.collections.MapConverter.populateMap(MapConverter.java:72)
at com.thoughtworks.xstream.converters.collections.MapConverter.unmarshal(MapConverter.java:67)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
... 42 more
Update 1:
Right, so... if I have:
ConfigurationParser class
public Storage parseConfiguration(String xmlFile)
throws FileNotFoundException
{
FileInputStream fis = new FileInputStream(xmlFile);
XStream xstream = new XStream();
xstream.autodetectAnnotations(true);
xstream.alias("storage", Storage.class);
return (Storage) xstream.fromXML(fis);
}
Repository class
public class Repository
{
@XStreamAlias(value = "name")
private String name;
@XStreamAlias (value = "basedir")
private String basedir;
@XStreamAlias (value = "policy")
private String policy = RepositoryPolicyEnum.MIXED.getPolicy();
@XStreamAlias (value = "layout")
private String layout = RepositoryLayoutEnum.MAVEN_2.getLayout();
@XStreamAlias (value = "type")
private String type = RepositoryTypeEnum.HOSTED.getType();
...
}
and:
configuration.xml
<storage>
<basedir>storages/storage0</basedir>
<repository>
<basedir>/here</basedir>
<name>repository0</name>
<policy>snapshots</policy>
<layout>maven2</layout>
<type>hosted</type>
</repository>
<repository>
<basedir>/here2</basedir>
<name>repository2</name>
<policy>snapshots</policy>
<layout>maven2</layout>
<type>hosted</type>
</repository>
</storage>
It works. However, I would like the configure.xml to look like:
<storage>
<basedir>storages/storage0</basedir>
<repositories>
<repository>
<name>repository0</name>
<policy>snapshots</policy>
<layout>maven2</layout>
<type>hosted</type>
</repository>
</repositories>
</storage>
Any suggestions...?
回答1:
Try this one
XStream xstream = new XStream();
xstream.alias("storage", Storage.class);
xstream.alias("repository", Map.class);
xstream.registerConverter(new MapEntryConverter());
Storage storage = (Storage) xstream.fromXML(fis);
System.out.println(storage);
and your converter
public static class MapEntryConverter implements Converter {
public boolean canConvert(Class clazz) {
return AbstractMap.class.isAssignableFrom(clazz);
}
public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {
AbstractMap map = (AbstractMap) value;
for (Object obj : map.entrySet()) {
Entry entry = (Entry) obj;
writer.startNode(entry.getKey().toString());
writer.setValue(entry.getValue().toString());
writer.endNode();
}
}
public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
Repository repo = new Repository();
while (reader.hasMoreChildren()) {
reader.moveDown();
String nodeName = reader.getNodeName();
if ("name".equalsIgnoreCase(nodeName)) {
repo.setName(reader.getValue());
} else if ("policy".equalsIgnoreCase(nodeName)) {
repo.setPolicy(reader.getValue());
} else if ("layout".equalsIgnoreCase(nodeName)) {
repo.setLayout(reader.getValue());
} else if ("type".equalsIgnoreCase(nodeName)) {
repo.setType(reader.getValue());
}
reader.moveUp();
}
return repo;
}
}
And my classes are simple pojos
public class Storage {
private String basedir;
private List<Repository> repositories = new ArrayList<Repository>();
...
}
public class Repository {
private String name;
private String policy;
private String layout;
private String type;
...
}
来源：https://stackoverflow.com/questions/17086757/how-to-unmarshal-map-using-xstream