我的Json代码如下
{
"data": [
{
"TEST": ["qasasas","zxXcxvxv"],
"id": "5892574",
},
{
"TEST": null,
"id": "121334",
}
]
}我的Freemarker模板Java代码如下
Gson g = new GsonBuilder()
.setLenient()
.create();
JsonObject resultsResponse = g.fromJson(content, JsonObject.class);
root.put(
"datalist",
resultsResponse);
Configuration cfg = new Configuration(Configuration.VERSION_2_3_27);
cfg.setDirectoryForTemplateLoading(new File("C:\\Users\\ponmanikandanb\\Desktop\\g\\freemarker"));
cfg.setDefaultEncoding("UTF-8");
cfg.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
cfg.setLogTemplateExceptions(true);
cfg.setWrapUncheckedExceptions(true);
cfg.setAPIBuiltinEnabled(true);
DefaultObjectWrapper owraop = new DefaultObjectWrapper(Configuration.VERSION_2_3_28);
owraop.setIterableSupport(true);
owraop.setExposeFields(true);
owraop.setExposureLevel(BeansWrapper.EXPOSE_ALL);
owraop.setMethodsShadowItems(true);
owraop.setForceLegacyNonListCollections(true);
owraop.setUseAdaptersForContainers(true);
cfg.setObjectWrapper(owraop);
Template temp = cfg.getTemplate("templates\\sampleAccountInflow.xml");
Writer out = new OutputStreamWriter(System.out);
temp.process(root, out);
String s = "";
out.write(s);
System.out.println(s);
我的Freemarker模板代码是
<#list accountList.data as response>
<#if response.TEST.isJsonNull()>is null</#if>
</#list>
如果我尝试检查数组TEST字段为null然后我得到低于异常。
Feb 27, 2019 1:34:14 PM freemarker.log._JULLoggerFactory$JULLogger error
SEVERE: Error executing FreeMarker template
FreeMarker template error:
For "." left-hand operand: Expected a hash, but this has evaluated to a collection (com.google.gson.JsonArray wrapped into f.t.DefaultIterableAdapter):
==> response.TEST [in template "templates\\sampleAccountInflow.xml" at line 18, column 16]
----
FTL stack trace ("~" means nesting-related):
- Failed at: #if response.TEST.isJsonNull() [in template "templates\\sampleAccountInflow.xml" at line 18, column 11]
----
Java stack trace (for programmers):
----
freemarker.core.NonHashException: [... Exception message was already printed; see it above ...]
at freemarker.core.Dot._eval(Dot.java:48)
at freemarker.core.Expression.eval(Expression.java:83)
at freemarker.core.MethodCall._eval(MethodCall.java:58)
at freemarker.core.Expression.eval(Expression.java:83)
at freemarker.core.Expression.evalToBoolean(Expression.java:161)
at freemarker.core.Expression.evalToBoolean(Expression.java:147)
at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:48)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.IteratorBlock$IterationContext.executedNestedContentForCollOrSeqListing(IteratorBlock.java:291)
at freemarker.core.IteratorBlock$IterationContext.executeNestedContent(IteratorBlock.java:271)
at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:242)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:642)
at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:107)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:93)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:336)
at freemarker.core.Environment.process(Environment.java:309)
at freemarker.template.Template.process(Template.java:384)
at com.temenos.data.transform.jsontoxml.JSONToXMLConversion.main(JSONToXMLConversion.java:83)
Exception in thread "main" FreeMarker template error:
For "." left-hand operand: Expected a hash, but this has evaluated to a collection (com.google.gson.JsonArray wrapped into f.t.DefaultIterableAdapter):
==> response.TEST [in template "templates\\sampleAccountInflow.xml" at line 18, column 16]
----
FTL stack trace ("~" means nesting-related):
- Failed at: #if response.TEST.isJsonNull() [in template "templates\\sampleAccountInflow.xml" at line 18, column 11]
----
Java stack trace (for programmers):
----
freemarker.core.NonHashException: [... Exception message was already printed; see it above ...]
at freemarker.core.Dot._eval(Dot.java:48)
at freemarker.core.Expression.eval(Expression.java:83)
at freemarker.core.MethodCall._eval(MethodCall.java:58)
at freemarker.core.Expression.eval(Expression.java:83)
at freemarker.core.Expression.evalToBoolean(Expression.java:161)
at freemarker.core.Expression.evalToBoolean(Expression.java:147)
at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:48)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.IteratorBlock$IterationContext.executedNestedContentForCollOrSeqListing(IteratorBlock.java:291)
at freemarker.core.IteratorBlock$IterationContext.executeNestedContent(IteratorBlock.java:271)
at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:242)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:642)
at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:107)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:93)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:336)
at freemarker.core.Environment.process(Environment.java:309)
at freemarker.template.Template.process(Template.java:384)
at com.temenos.data.transform.jsontoxml.JSONToXMLConversion.main(JSONToXMLConversion.java:83)
首先，我将Json转换为GSON（JsonObject）数据并映射到map以进行freemarker模板处理。所有其他工作正在工作，而我为JsonArray对象检查null正在收到错误。如果我检查null为正常值，它的工作正常。
以下解决方案将起作用。我们需要从DefaultObjectWrapper覆盖wrap方法。
public class GsonObjectWraper extends DefaultObjectWrapper {
public GsonObjectWraper(Version incompatibleImprovements){
super(incompatibleImprovements);
}
@Override
public TemplateModel wrap(Object obj) throws TemplateModelException {
if (obj == null) {
return super.wrap(null);
}
if (obj instanceof JsonArray) {
return handleUnknownType(obj);
}
return super.wrap(obj);
}
}