XStream 1.4.10版本处理xml使用问题

XStream pom依赖：

<dependency>
    <groupId>com.thoughtworks.xstream</groupId>
    <artifactId>xstream</artifactId>
    <version>1.4.10</version>
</dependency>    

1、对象解析成xml字符串时下划线变成双下划线

解决：

xStream = new XStream(new DomDriver("UTF-8", new XmlFriendlyNameCoder("_-", "_")));

或者

xStream = new XStream(new Xpp3Driver(new NoNameCoder()));

2、Security framework of XStream not initialized, XStream is probably vulnerable

解决：

XStream.setupDefaultSecurity(xStream);
xStream.allowTypesByWildcard(new String[] {
      "com.common.util.**"  //你的包路径
});

3、处理既有属性又有值的情况

形如：<Query Code="1">select * from user</Query>

使用自定义转换器实现,如下：

public class QueryConverter implements Converter {
    @Override
    public boolean canConvert(Class type) {
        return type.equals(Query.class);
    }

    /**
     * 将java对象转为xml时使用
     */
    @Override
    public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
        Query query = (Query) source;
        // 设置属性值
        writer.addAttribute("Code", query.getCode());
        // 设置文本值
        writer.setValue(query.getText());
    }

    /**
     * 将xml转为java对象使用
     */
    @Override
    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
        Query query = new Query();
        query.setTransactionCode(reader.getAttribute("Code"));
        query.setText(reader.getValue());
        return query;
    }
}

之后通过注解@XStreamConverter(value = QueryConverter.class)

或代码注册转换器使用：

xStream.registerConverter(new xxxConverter());

4、时间转换器

字段为Date类型

public class DateConverter implements Converter {

    @Override
    public boolean canConvert(Class arg0) {
        return Date.class == arg0;
    }

    @Override
    public void marshal(Object arg0, HierarchicalStreamWriter arg1, MarshallingContext arg2) {
    }

    @Override
    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext arg1) {

        GregorianCalendar calendar = new GregorianCalendar();
        //格式化当前系统日期
        SimpleDateFormat dateFm = new SimpleDateFormat("yyyy-MM-dd");
        try {
            calendar.setTime(dateFm.parse(reader.getValue()));
        } catch (ParseException e) {
            throw new ConversionException(e.getMessage(), e);
        }

        return calendar.getTime();
    }
}

使用：

@XStreamConverter(DateConverter.class)
private Date beginTime;

属性为Date类型处理SingleValueConverter

public class XStreamDateConverter implements SingleValueConverter {

    @Override
    public boolean canConvert(Class arg0) {
        return Date.class == arg0;
    }

    @Override
    public Object fromString(String arg0) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return format.parse(arg0);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    public String toString(Object arg0) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return format.format((Date) arg0);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

}

之后将转化加在Date属性的字段上使用即可

@XStreamConverter(value=XStreamDateConverter.class)
@XStreamAsAttribute
private Date beginTime;

5、针对null值的字段也显示在xml中处理

大概思路就是遍历对象的所有的字段，若当前字段的值为null，则处理成空字符串，示例自定义转换器如下：

public class FieldConverter implements Converter {

    /**
     * 日志记录
     */
    private static final Logger LOGGER = LoggerFactory.getLogger(FieldConverter.class);

    /**
     * 时间格式
     */
    private String formatPattern;

    public FieldConverter() {
    }

    public FieldConverter(String formatPattern) {
        this.formatPattern = formatPattern;
    }

    @Override
    public boolean canConvert(Class type) {
        return true;
    }

    /**
     * 将java对象转为xml时使用
     */
    @Override
    public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
        try {
            handleSource(source, writer);
        } catch (Exception e) {
            LOGGER.error("[FieldConverter] marshal 异常，{}", e);
            throw new IllegalArgumentException("转换xml出错");
        }
    }

    /**
     * @description ：处理对象为xml转换
     * @param source 对象源
     * @param writer 流写出对象
     * @date  2019/9/29 18:48
     * @modifier
     * @return  void
     */
    private void handleSource(Object source, HierarchicalStreamWriter writer) throws IllegalAccessException {

        try {
            Class<?> aClass = source.getClass();
            Field[] declaredFields = aClass.getDeclaredFields();
            for (Field currField : declaredFields) {
                currField.setAccessible(Boolean.TRUE);
                // 字段注解
                boolean isAttr = currField.isAnnotationPresent(XStreamAsAttribute.class);
                boolean isXStreamAlias = currField.isAnnotationPresent(XStreamAlias.class);
                boolean isFieldValue = currField.isAnnotationPresent(FieldValue.class);

                // 当前字段值
                Object curFieldValue = currField.get(source);

                // 字段别名
                String xmlAlias;
                if (isXStreamAlias) {
                    xmlAlias = currField.getAnnotation(XStreamAlias.class).value();
                } else {
                    xmlAlias = currField.getName();
                }

                if (isAttr) {
                    // 字段属性
                    writer.addAttribute(xmlAlias, null == curFieldValue ? "" : String.valueOf(curFieldValue));
                } else if (isFieldValue) {
                    // 字段值
                    writer.setValue(String.valueOf(curFieldValue));
                } else {
                    // 字段简单处理
                    boolean isBaseType = DomainUtil.isBaseType(currField.getType());
                    if (curFieldValue instanceof List) {
                        List<Object> list = (List<Object>) curFieldValue;
                        for (int i = 0; i < list.size(); i++) {
                            writer.startNode(xmlAlias + i);
                            Object curr = list.get(i);
                            isBaseType = DomainUtil.isBaseType(curr.getClass());
                            if (null == curr || isBaseType) {
                                writer.setValue(null == curr ? "" : String.valueOf(curr));
                            } else {
                                handleSource(curr, writer);
                            }
                            writer.endNode();
                        }
                    } else {
                        // 开始节点
                        writer.startNode(xmlAlias);

                        if (null == curFieldValue || isBaseType) {
                            writer.setValue(null == curFieldValue ? "" : String.valueOf(curFieldValue));
                        } else if (currField.getType().equals(Date.class)) { //时间对象
                            SimpleDateFormat format = new SimpleDateFormat(formatPattern);
                            writer.setValue(null == curFieldValue ? "" : format.format(curFieldValue));
                        } else { //对象类型
                            handleSource(curFieldValue, writer);
                        }

                        // 结束节点
                        writer.endNode();
                    }
                }
            }
        } catch (Exception e) {
            LOGGER.error("[FieldConverter] handleSource 异常，{}", e);
            throw e;
        }
    }

    /**
     * 将xml转为java对象使用
     */
    @Override
    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
        System.out.println("coming.....");
        return null;
    }

源码参照 GitHub