xml对象与字符串互换

很多老系统，特别是C++的系统，可能数据结构采用的xml。xml对java来说没有什么，但是C++来说，可能还有个顺序问题，毕竟c++没有那么多通用类库。
2 xstream
先说依赖，我本来不想升级，但是有个问题卡者就给升了，虽然升了并没有解决我的问题。

     <!-- xstream 升级到1.4.18后 依赖的jar --><dependency><groupId>com.thoughtworks.xstream</groupId><artifactId>xstream</artifactId><version>1.4.20</version></dependency><dependency><groupId>xmlpull</groupId><artifactId>xmlpull</artifactId><version>1.1.3.4d_b4_min</version></dependency><dependency><groupId>xpp3</groupId><artifactId>xpp3_min</artifactId><version>1.1.4c</version></dependency>

2.3 字符串转对象转换不全的问题
之所以转换不全，可以确定，应该javabean中对象属性，与xml字符串字段不匹配
java对象的结构如下
第一层

@Data
@XStreamAlias("business")
public class RespInvoiceIssue026295Bean extends BusinessBean implements ResponseBean<RespBodyBean> {private RespInvoiceIssueBody026295Bean body;public RespInvoiceIssue026295Bean() {super();}public RespInvoiceIssue026295Bean(String id) {super(id);}public RespInvoiceIssue026295Bean(String id, String comment) {super(id, comment);}}

第二层

@XStreamAlias("body")
public class RespInvoiceIssueBody026295Bean extends RespBodyBean implements Serializable {

第三层

@Data
public class RespInvoiceIssue026295ReturnData implements Serializable {

2.2 双下划线问题
看下面注释

    public static String toXml(Object obj) {
//        XStream xstream = new XStream(new DomDriver(encoding));XStream xstream = new XStream(new Xpp3Driver(new NoNameCoder())); // 解决xml双下划线的问题//            XStream xstream=new XStream(new DomDriver()); //直接用jaxp dom来解释//            XStream xstream=new XStream(new DomDriver("utf-8")); //指定编码解析器,直接用jaxp dom来解释//如果没有这句，xml中的根元素会是<包.类名>；或者说：注解根本就没生效，所以的元素名就是类的属性xstream.processAnnotations(obj.getClass()); //通过注解方式的，一定要有这句话return xstream.toXML(obj);}

2.1 复杂对象转换的问题
一般的复杂结构还不会有问题，但是老式的默认却不行，很奇怪。
跟踪代码调试，发现有一个被解释为String类型了

看看我的结构
第一层


@Data
@XStreamAlias("business")
public class ReqInvoiceIssue026Bean extends BusinessBean implements RequestBean {/****/private static final long serialVersionUID = 279889115759202804L;@XStreamAlias("REQUEST_COMMON_FPKJ")private ReqInvoiceIssueBody026Bean body;

第二层

@Data
@XStreamAlias("REQUEST_COMMON_FPKJ")
public class ReqInvoiceIssueBody026Bean implements Serializable {/****/private static final long serialVersionUID = 7806868114280462342L;@XStreamAlias("class")@XStreamAsAttributeprivate String cls = "REQUEST_COMMON_FPKJ";@XStreamAlias("COMMON_FPKJ_FPT")private ReqInvoiceIssueFyxm026Bean fyxm;@XStreamAlias("COMMON_FPKJ_XMXXS")private ReqInvoiceIssueFyxmGroup026Bean xmxxs;
}

第三层,到了第三层的时候，解析失败。

@Data
@XStreamAlias("COMMON_FPKJ_XMXXS")
public class ReqInvoiceIssueFyxmGroup026Bean implements Serializable {@XStreamAlias("class")@XStreamAsAttributeprivate String cls = "COMMON_FPKJ_XMXX";@XStreamAsAttributeprivate Integer size;@XStreamImplicit(itemFieldName = "COMMON_FPKJ_XMXX")private List<ReqInvoiceIssueFyxmGroupXmxx026Bean> xmxx;

第四层

@Data
public class ReqInvoiceIssueFyxmGroupXmxx026Bean implements Serializable {

异常信息如下：


com.thoughtworks.xstream.converters.ConversionException: 
---- Debugging information ----
cause-exception     : com.thoughtworks.xstream.mapper.CannotResolveClassException
cause-message       : COMMON_FPKJ_XMXX
class               : com.whty.einv.sks.model.params.req.body.ReqInvoiceIssueBody026Bean
required-type       : com.whty.einv.sks.model.params.req.body.ReqInvoiceIssueBody026Bean
converter-type      : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
path                : /business/REQUEST_COMMON_FPKJ/COMMON_FPKJ_XMXXS
line number         : 32
class[1]            : com.whty.einv.sks.model.params.req.business.ReqInvoiceIssue026Bean
required-type[1]    : com.whty.einv.sks.model.params.req.business.ReqInvoiceIssue026Bean
version             : 1.4.20
-------------------------------at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:81)at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:72)at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:68)at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:499)at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:425)at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:277)at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:74)at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:72)at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:68)at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:52)at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:136)at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1464)at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1441)at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1321)at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1312)at com.whty.einv.sks.model.util.XmlUtil.toBean(XmlUtil.java:53)at com.whty.einv.sks.model.test.TestJavaToXml.toBean(TestJavaToXml.java:108)at com.whty.einv.sks.model.test.TestJavaToXml.test10_026(TestJavaToXml.java:86)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:498)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)at org.junit.runners.ParentRunner.run(ParentRunner.java:363)at org.junit.runner.JUnitCore.run(JUnitCore.java:137)at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)
Caused by: com.thoughtworks.xstream.mapper.CannotResolveClassException: COMMON_FPKJ_XMXXat com.thoughtworks.xstream.mapper.DefaultMapper.realClass(DefaultMapper.java:81)at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:125)at com.thoughtworks.xstream.mapper.DynamicProxyMapper.realClass(DynamicProxyMapper.java:55)at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:125)at com.thoughtworks.xstream.mapper.PackageAliasingMapper.realClass(PackageAliasingMapper.java:88)at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:125)at com.thoughtworks.xstream.mapper.ClassAliasingMapper.realClass(ClassAliasingMapper.java:79)at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:125)at com.thoughtworks.xstream.mapper.ArrayMapper.realClass(ArrayMapper.java:74)at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:125)at com.thoughtworks.xstream.mapper.SecurityMapper.realClass(SecurityMapper.java:71)at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:125)at com.thoughtworks.xstream.mapper.CachingMapper.realClass(CachingMapper.java:47)at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:420)at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:277)at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:74)... 40 moreProcess finished with exit code -1

经过多轮尝试，问题的根源在@XStreamAlias("class")，这个class是不是跟什么冲突了。

找到问题了，问题也将迎刃而解。

        //注意：不是new Xstream(); 否则报错：java.lang.NoClassDefFoundError: org/xmlpull/v1/XmlPullParserFactory
//        XStream xstream = new XStream();XStream xstream = new XStream(new Xpp3Driver(new NoNameCoder())); // 解决xml双下划线的问题// 去掉class属性xstream.aliasSystemAttribute(null,"class");//解决XStream的安全警告xstream.addPermission(AnyTypePermission.ANY);
//        XStream.setupDefaultSecurity(xstream);xstream.allowTypes(new Class[]{cls});//扫描注解xstream.processAnnotations(cls);T obj = (T) xstream.fromXML(xmlStr);return obj;

.1 jibx实现
先看依赖，使用这个技术比较麻烦一点，就是再打包的时候要执行mvn jibx:bind

  <dependency><groupId>org.jibx</groupId><artifactId>jibx-run</artifactId><version>1.3.1</version></dependency><dependency><groupId>org.jibx</groupId><artifactId>jibx-extras</artifactId><version>1.3.1</version><scope>test</scope></dependency><dependency><groupId>org.jibx</groupId><artifactId>jibx-tools</artifactId><version>1.3.1</version><scope>test</scope></dependency>

再看打包

<build><plugins><!-- 源码插件 --><plugin><artifactId>maven-source-plugin</artifactId><version>2.1</version><configuration><attach>true</attach></configuration><executions><execution><phase>compile</phase><goals><goal>jar</goal></goals></execution></executions></plugin><plugin><groupId>org.jibx</groupId><artifactId>jibx-maven-plugin</artifactId><version>1.3.1</version><configuration><schemaBindingDirectory>src/main/resources</schemaBindingDirectory><includeSchemaBindings><!-- 每次执行前需要先mvn clean compile test-compile或手动删除Jibx生成的文件，再执行mvn jibx:bind，有相同类名时，一次性会执行失败  --><!-- jibx生成的所有类文件会位于第一个生成的类的同目录下，分开执行可以在不同的文件夹生成对应类 --><includeSchemaBindings>binding/request/*-binding.xml</includeSchemaBindings><includeSchemaBindings>binding/response/*-binding.xml</includeSchemaBindings></includeSchemaBindings><verbose>true</verbose></configuration><executions><execution><goals><goal>bind</goal></goals></execution></executions></plugin></plugins><resources><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource></resources></build>

使用如下

	/*** obj转xml** @param obj* @param indent 格式化缩进* @return String* @throws JiBXException*/public static String toXml(Object obj, int indent) throws JiBXException {IBindingFactory bfact = BindingDirectory.getFactory(obj.getClass());IMarshallingContext mctx = bfact.createMarshallingContext();mctx.setIndent(indent);StringWriter writer = new StringWriter();mctx.marshalDocument(obj, encoding, null, writer);return writer.toString();}/*** xml转obj** @param xml* @param clazz* @return* @throws JiBXException*/public static <T> T fromXml(String xml, Class<T> clazz) throws JiBXException {IBindingFactory bfact = BindingDirectory.getFactory(clazz);IUnmarshallingContext uctx = bfact.createUnmarshallingContext();Object obj = uctx.unmarshalDocument(new StringReader(xml), null);return clazz.cast(obj);}