学步园

1, jettison

jettison可以转换json和xml格式，并通过这种途径来将json字符串解析成Java对象。其采用STAX的方式进行json转换，用法如下

public class Parse
{
	/**
	 * @param args
	 * @throws JSONException 
	 */
	public static void main(String[] args) throws JSONException
	{
		JSONObject userString = new JSONObject("{\"jaxb\":{\"name\" : \"abc\"}}");

		AbstractXMLStreamReader reader = null;
        try
        {
	        reader = new MappedXMLStreamReader(userString);
	        
	        try
            {
	            JAXBContext jc = JAXBContext.newInstance(Jaxb.class);
	            
	            Unmarshaller unmarshaller = jc.createUnmarshaller();
	            
	            Object jaxb = unmarshaller.unmarshal(reader);
	            
	            System.out.println(jaxb);
	            
	            StringWriter sw = new StringWriter();
	            MappedNamespaceConvention con = new MappedNamespaceConvention(new Configuration());
	            XMLStreamWriter xsw = new MappedXMLStreamWriter(con, sw);
	            
	            Marshaller marshaller = jc.createMarshaller();
	            marshaller.marshal(jaxb, xsw);
	            
	            System.out.println(sw.toString());
	            try
                {
	                sw.close();
                } catch (IOException e)
                {
	                e.printStackTrace();
                }
	            
            } catch (JAXBException e)
            {
	            e.printStackTrace();
            }
        } catch (XMLStreamException e1)
        {
	        e1.printStackTrace();
        }
		
        if (reader != null)
        {
			try
            {
                reader.close();
            } catch (XMLStreamException e)
            {
                e.printStackTrace();
            }
        }
	}

}

 

2，jackson

jackson可以提供灵活的转换策略，例如是否在转换中将根属性识别为对象类型（jettison会，json-lib不会，jackson默认不会，根据选项判断），在遇到不能识别的属性时是否抛出异常（jettison不会，json-lib不会，jackson默认会，可根据选项判断）等

public class DataBindingParser
{

	/**
	 * @param args
	 */
	@SuppressWarnings("unchecked")
    public static void main(String[] args)
	{
		String userString = "{\"User\":{\"name\" : { \"first\" : \"Joe\", \"last\" : \"Sixpack\" },\"gender\" : \"MALE\", \"verified\" : false, \"userImage\" : \"Rm9vYmFyIQ==\"}}";
		String userStringEx = "{\"name\" : { \"first\" : \"Joe\", \"last\" : \"Sixpack\" },\"gender\" : \"MALE\", \"age\" : 18, \"verified\" : false, \"userImage\" : \"Rm9vYmFyIQ==\"}";
		
		ObjectMapper mapper = new ObjectMapper(); 
		
		try
		{
			mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE);
			mapper.enable(SerializationFeature.WRAP_ROOT_VALUE);
			User user = mapper.readValue(userString, User.class);
			System.out.println("userString-->" + user);
			System.out.println("userString<--" + mapper.writeValueAsString(user));
			
			mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
			mapper.disable(DeserializationFeature.UNWRAP_ROOT_VALUE);
			User userEx = mapper.readValue(userStringEx, User.class);
			System.out.println("userStringEx-->" + userEx);
			System.out.println("userStringEx<--" + mapper.writeValueAsString(userEx));
			System.out.println("=========================");
			
            Map<String,Object> userData = mapper.readValue(userString, Map.class);
			System.out.println("userString-->" + userData);
			System.out.println("userString<--" + mapper.writeValueAsString(userData));
			
            Map<String,Object> userDataEx = mapper.readValue(userStringEx, Map.class);
			System.out.println("userStringEx-->" + userDataEx);
			System.out.println("userStringEx<--" + mapper.writeValueAsString(userDataEx));
			
		} catch (JsonParseException e)
		{
			e.printStackTrace();
		} catch (JsonMappingException e)
		{
			e.printStackTrace();
		} catch (IOException e)
		{
			e.printStackTrace();
		}
	}

}