jaxb实现xml 和 json 之间的转换

jaxb2 实体类转xml：

public static String toXML(Object obj, String encode, boolean format, boolean fragment) {
try {
JAXBContext jaxbContext = JAXBContext.newInstance(obj.getClass());
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_ENCODING, encode);           // 编码格式
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, format);   // 是否格式化生成的xml串
marshaller.setProperty(Marshaller.JAXB_FRAGMENT, fragment);         // 是否省略xm头声明信息
StringWriter writer = new StringWriter();
marshaller.marshal(obj, writer);
return writer.toString();
} catch (Exception e) {
throw new RuntimeException(e);
}
}

jaxb2 xml转实体类:

public static <T> T fromXML(String xml, Class<T> valueType) {
try {
JAXBContext jaxbContext = JAXBContext.newInstance(valueType);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
return (T) unmarshaller.unmarshal(new StringReader(xml));
} catch (Exception e) {
throw new RuntimeException(e.getMessage());
}
}

优化：

static Map<String, JAXBContext> jaxbContextMap = new HashMap<String, JAXBContext>();

/**
* java实体类转xml
*/
public static String toXML(Object obj, String encode, boolean format, boolean fragment) {
try {
JAXBContext jaxbContext = jaxbContextMap.get(obj.getClass().getName());
if(jaxbContext == null){
// 如果每次都调用JAXBContext.newInstance方法，会导致性能急剧下降
jaxbContext = JAXBContext.newInstance(obj.getClass());
jaxbContextMap.put(obj.getClass().getName(), jaxbContext);
}

Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_ENCODING, encode);           // 编码格式

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marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, format);   // 是否格式化生成的xml串
marshaller.setProperty(Marshaller.JAXB_FRAGMENT, fragment);         // 是否省略xm头声明信息
StringWriter writer = new StringWriter();
marshaller.marshal(obj, writer);
return writer.toString();
} catch (Exception e) {
throw new RuntimeException(e);
}
}

/**
* xml转java实体类
*/

@SuppressWarnings("unchecked")
public static <T> T fromXML(String xml, Class<T> valueType) {
try {
JAXBContext jaxbContext = jaxbContextMap.get(valueType.getName());
if(jaxbContext == null){
jaxbContext = JAXBContext.newInstance(valueType);
jaxbContextMap.put(valueType.getName(), jaxbContext);
}
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
return (T) unmarshaller.unmarshal(new StringReader(xml));
} catch (Exception e) {
throw new RuntimeException(e.getMessage());
}
}