Java對象轉xml字符串

需求主要是用於數據的傳輸，系統先將所需數據以對象形式封裝填充出來，然后再由對象轉為xml

1，首先定義一個接口，定義一個創建xml的方法

public interface IFileCreateService {
    FileReturnModel createFile(Object object) throws MessageConvertException;
}

2，接下來是實現方法

@Override
public FileReturnModel createFile(Object object) throws MessageConvertException {
    FileReturnModel fileReturnModel = new FileReturnModel();
    XMLOutputFactory factory = XMLOutputFactory.newInstance();
    StringWriter sw = new StringWriter();
    XMLStreamWriter writer = null;
    try {
        writer = factory.createXMLStreamWriter(sw);
        createTitle(writer);
        createBody(writer, object);
    } catch (XMLStreamException e) {
        e.printStackTrace();
        throw new MessageConvertException("報文轉換異常 XMLStreamException", e);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
        throw new MessageConvertException("報文轉換異常 IllegalAccessException", e);
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
        throw new MessageConvertException("報文轉換異常 NoSuchMethodException", e);
    } catch (InvocationTargetException e) {
        e.printStackTrace();
        throw new MessageConvertException("報文轉換異常 InvocationTargetException", e);
    } catch (Exception e) {
        e.printStackTrace();
        throw new MessageConvertException("報文轉換異常 NoSuchFieldException", e);
    } finally {
        try {
            if (null != writer) {
                writer.flush();
                writer.close();
                fileReturnModel.setFileContext(sw.toString());
            }
        } catch (XMLStreamException e) {
            e.printStackTrace();
            throw new MessageConvertException("報文轉換異常 流關閉錯誤 XMLStreamException", e);
        }
    }
    return fileReturnModel;
}

3，createTitle()方法作用是編寫標題信息，也就是xml頭部信息，定義約束

protected void createTitle(XMLStreamWriter writer) throws XMLStreamException {
        writer.writeStartDocument("UTF-8", "1.0");
//        writer.writeCharacters("\n");
    }

4，createBody()方法

private void createBody(XMLStreamWriter writer, Object obj) throws XMLStreamException, IllegalArgumentException, IllegalAccessException, SecurityException, NoSuchMethodException, InvocationTargetException,UnsupportedEncodingException,NoSuchFieldException {
    if (obj.getClass().isAnnotationPresent(Model.class)) {
 Model model = obj.getClass().getAnnotation(Model.class);
        writer.writeStartElement(model.name());
        writeXmlBody(writer, obj.getClass(), obj);
        writer.writeEndElement();
    }
}
紅色字體的Model是定義的@Model注解，用於擴展屬性，如下圖，model.name()就是"CONTRACT"

 

 

 

 5，writeXmlBody()方法編寫具體的標簽及屬性

protected void writeXmlBody(XMLStreamWriter writer,Class clas, Object object) throws XMLStreamException, IllegalArgumentException, IllegalAccessException, SecurityException, NoSuchMethodException, InvocationTargetException, UnsupportedEncodingException, NoSuchFieldException {
        Field[] fields = clas.getDeclaredFields();
        for (Field field : fields) {
            field.setAccessible(true);
            Property propertyAnnotation = field.getAnnotation(Property.class);
            if (null == propertyAnnotation){
                continue;
            }
            if (Collection.class.isAssignableFrom(field.getType())) {//集合
                Collection collection = (Collection) field.get(object);
                if (collection != null) {
                    for (Object objInner : collection) {
                        writeXmlBody(writer, objInner.getClass(),objInner);
                    }
                }
            } else if (Date.class.isAssignableFrom(field.getType())) {//日期
                Date date = (Date) field.get(object);
                writer.writeStartElement(propertyAnnotation.name());
                writer.writeCharacters(formateDate(date));
                writer.writeEndElement();

            } else if (String.class.isAssignableFrom(field.getType())||Double.class.isAssignableFrom(field.getType())||Integer.class.isAssignableFrom(field.getType())||Float.class.isAssignableFrom(field.getType())||Character.class.isAssignableFrom(field.getType())|| BigDecimal.class.isAssignableFrom(field.getType())) {
                writer.writeStartElement(propertyAnnotation.name());
                writer.writeCData(fillData(field.get(object)));
                writer.writeEndElement();
            } else if(byte[].class.isAssignableFrom(field.getType())){//字節
                writer.writeStartElement(propertyAnnotation.name());
                if(null!=field.get(object)){
                    byte[] bytes= (byte[]) field.get(object);
                    writer.writeCData(new String(bytes,"GBK"));
                }else{
                    writer.writeCData("");
                }
                writer.writeEndElement();
            }
            else {//類對象
                Object obj = field.get(object);
                if(!"model".equals(field.getName())){
                    writer.writeStartElement(propertyAnnotation.name());
                }
                if (null != obj) {
                    writeXmlBody(writer, obj.getClass(),obj);//這里使用了遞歸
                    //加載父類的屬性
                    writeXmlBody(writer, obj.getClass().getSuperclass(),obj);
                }
                if(!"model".equals(field.getName())) {
                    writer.writeEndElement();
                }
            }
        }
    }

需要注意，由於示例中，我給Contract對象使用了@Model注解，其成員變量，我使用@Property注解，那么在writeXmlBody()方法中，我編寫xml取的是注解中的屬性，也就是說大寫的CONTRACT，
CONTRACTCODE。轉化后的結果是這樣的

 

 

 如果不適用注解屬性，使用對象原本的屬性，則 propertyAnnotation.name() 需要替換成 field.getName()，轉化后的結果是這樣的

 

 6，方法中使用遞歸的作用是循環遍歷類對象中的所有子類對象，孫類對象，重孫對象等等，就是嵌套。方法大致是這些，需要引入對應的依賴，注意異常的捕獲及流的釋放等，以上代碼是個人編寫過使用過，這里記錄一下便於以后快速記起，也希望小伙伴們能給出更好的對象轉xml方法，謝謝。