JSON to JAVA object, then to XML

Requirements: The policy system requires us to pass in a string in XML format, and the project accepts a JSON. Since the format of this XML is a bit unconventional, not all attributes are key-value pairs, as shown below:

Document your own experience doing this so you can recall it later

JSON to JAVA object

The general format is as follows:

So we create the corresponding entity class, because the final XML is China, so create a China class, and create the attribute Name and 4 custom classes according to the hierarchical relationship

     China
        Level 1: Beijing
       Level 1: Shenzen
           　　Level 2: Nanshan
            　  Level 2: Futian

Add the annotation @JSONField(name = "name in JSON") to the property

By the way, rewrite toString, each custom class is

 

    public  static  void main (String [] args) throws a JAXBException, IOException, DocumentException {
         // JSON parsed into objects - String troublesome because JSON written, to turn into a re-decoded Base64 actual 
        String STR = "+ eUsCJ9fX0 eyJOYW1lIjoi5Lit5Zu9IiwiQmVpamluZyI6eyJOYW1lIjoi5YyX5LqsIn0sIlNoZW56aGVuIjp7Ik5hbWUiOiLmt7HlnLMiLCJOYW5zaGFuIjp7Ik5hbWUiOiLljZflsbEiLCJQcmljZSI6MTIzLCJEYXRlIjoiMjAxOC0wNC0yOCJ9LCJGdXRpYW4iOnsiTmFtZSI6Iuemj =" ; 
　　　　 STR = Base64Coder.decodeString(str); 
　　　　// Call Google's FastJson, and the conversion is simple and successful.
        China china = JSON.toJavaObject(JSON.parseObject(str), China.class);
        System.out.println(china.toString());
        
    }

 Object to XML

First add the following two annotations on each custom class

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "converted XML name")

Then add annotations to each individual attribute, under the JSON annotation above, if it is a node:

@XmlElement(name = "node name")

If it is an attribute:

@XmlAttribute(name = "Attribute name")

Some special formats, such as Date, can set the format of XML. For example, in the requirement, I only need Date and not hours, minutes and seconds. So add on the corresponding Date property:

@XmlSchemaType(name = "date")

 

Go back to the method, use the package that comes with JDK for parsing, add a method, pass in the entity class and return a string

/** 
     * @Title: beanToXml
     * @Description: JAVA object converted to XML string
     * @param application
     * @throws JAXBException
     * @throws PropertyException parameter description
     * @return void return type
      */ 
    public  static String beanToXml(Object object) throws JAXBException {
        JAXBContext jc = JAXBContext.newInstance(object.getClass());
        Marshaller marshaller = jc.createMarshaller();
         // whether to format the output 
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, false );
         // set the encoding format 
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8" );
         // whether not Display header information 
        marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true );
        StringWriter writer = new StringWriter();
        marshaller.marshal(object, writer);
        // Remove time zone information in date 
        return writer.toString().replaceAll("\\+08:00", "" );
    }

It's almost normal to this step, but there is actually nothing to display in the head, and there are still empty nodes using </>

There are many similar examples on the Internet, but there are all kinds of unsatisfactory ones. In fact, the solution is very simple, just turn it again!

remove empty nodes

/** 
     * @Title: formatXmlEmptyElements
     * @Description: Format the empty node of the XML string, <example/> is converted to <example></example>
     * @param xml
     * @return
     * @throws IOException
     * @throws DocumentException parameter description
     * @return String    返回类型
     */
    public static String formatXmlEmptyElements(String xml) throws IOException, DocumentException {
        OutputFormat xmlFormat = OutputFormat.createPrettyPrint();
         // Set the expansion empty node 
        xmlFormat.setExpandEmptyElements( true );
        StringWriter out = new StringWriter();
        XMLWriter writer = new XMLWriter(out, xmlFormat);
        writer.write(DocumentHelper.parseText(xml));
        return out.toString();
    }

Put the complete main method

    public static void main(String[] args) throws JAXBException, IOException, DocumentException {
        //json解析成对象
        String str = "eyJOYW1lIjoi5Lit5Zu9IiwiQmVpamluZyI6eyJOYW1lIjoi5YyX5LqsIn0sIlNoZW56aGVuIjp7Ik5hbWUiOiLmt7HlnLMiLCJOYW5zaGFuIjp7Ik5hbWUiOiLljZflsbEiLCJQcmljZSI6MTIzLCJEYXRlIjoiMjAxOC0wNC0yOCJ9LCJGdXRpYW4iOnsiTmFtZSI6Iuemj+eUsCJ9fX0=";
        str = Base64Coder.decodeString(str);
        China china = JSON.toJavaObject(JSON.parseObject(str), China.class);
        System.out.println(china.toString());
        // The object is parsed into XML format 
        String xmlString = beanToXml(china);
        System.out.println(xmlString);
        // Add trailing blank node 
        System.out.println(formatXmlEmptyElements(xmlString));
    }

result: