Jackson Full Data Binding: Difference between revisions

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=Overview=
=Overview=
Full data binding deserializes JSON into a custom Java type, using reflection to "fill out" the state.


=JSON to Java=
=JSON to Java=


<pre>
<syntaxhighlight lang='java'>
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectMapper;


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Root root = mapper.readValue(is, Root.class);
Root root = mapper.readValue(is, Root.class);
</pre>
</syntaxhighlight>


This is a generic conversion method, assuming that the JSON content matches the internal structure of the type <T>:
This is a generic conversion method, assuming that the JSON content matches the internal structure of the type <T>:


<pre>
<syntaxhighlight lang='java'>
public static <T> T fromJson(String json, Class<? extends T> c) throws JsonConversionException {
public static <T> T fromJson(String json, Class<? extends T> c) throws JsonConversionException {


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     }
     }
}
}
</pre>
</syntaxhighlight>


=Java to JSON=
=Java to JSON=
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Example:
Example:


<pre>
<syntaxhighlight lang='java'>
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectMapper;


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mapper.writeValue(baos, root);
mapper.writeValue(baos, root);
System.out.println(new String(baos.toByteArray()));
System.out.println(new String(baos.toByteArray()));
</pre>
</syntaxhighlight>


=Code Example=
=Code Examples=


{{External|[https://github.com/NovaOrdis/playground/blob/master/json/jackson/full-data-binding/src/main/java/io/novaordis/playground/json/jackson/fulldatabinding/Main.java Full Data Binding Example]}}
{{External|[https://github.com/NovaOrdis/playground/blob/master/json/jackson/07-full-data-binding/src/main/java/io/novaordis/playground/json/jackson/fulldatabinding/Main.java Full Data Binding Example]}}
{{External|[https://github.com/ovidiuf/playground/tree/master/json/jackson/07.1-full-data-binding-variants Full Data Binding Example 2]}}


=Generics Handling=
=Generics Handling=
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<span id="generic_type_information"></span>To enable generic type information (like "Map<String,Object>"), you have to use TypeReference container. See http://wiki.fasterxml.com/JacksonDataBinding.
<span id="generic_type_information"></span>To enable generic type information (like "Map<String,Object>"), you have to use TypeReference container. See http://wiki.fasterxml.com/JacksonDataBinding.


{{External|[https://github.com/NovaOrdis/playground/blob/master/json/jackson/full-data-binding-and-generics/src/main/java/io/novaordis/playground/json/jackson/fulldatabinding/Main.java Full Data Binding and Generics Example]}}
{{External|[https://github.com/NovaOrdis/playground/blob/master/json/jackson/08-full-data-binding-and-generics/src/main/java/io/novaordis/playground/json/jackson/fulldatabinding/Main.java Full Data Binding and Generics Example]}}
 
=Annotations=
 
{{Internal|Jackson Annotations|Jackson Annotations}}
 
=Abstract Class Handling=
 
{{Internal|Jackson Full Data Binding and Abstract Class Handling|Abstract Class Handling}}
 
=Custom Deserializers=
 
{{Internal|Jackson Full Data Binding and Custom Deserializers|Custom Deserializers}}

Latest revision as of 21:50, 14 November 2018

Internal

Overview

Full data binding deserializes JSON into a custom Java type, using reflection to "fill out" the state.

JSON to Java

import com.fasterxml.jackson.databind.ObjectMapper;

InputStream is = ...;

ObjectMapper mapper = new ObjectMapper();

Root root = mapper.readValue(is, Root.class);

This is a generic conversion method, assuming that the JSON content matches the internal structure of the type <T>:

public static <T> T fromJson(String json, Class<? extends T> c) throws JsonConversionException {

    try {
        ObjectMapper objectMapper = new ObjectMapper();
        return objectMapper.readValue(new ByteArrayInputStream(json.getBytes()), c);
    }
    catch (Exception e) {
       throw new JsonConversionException(e);
    }
}

Java to JSON

ObjectMapper will introspect a Java object coded according to the Java Beans conventions and output it as JSON content.

The method names (without the "get") will be used as field names.

Example:

import com.fasterxml.jackson.databind.ObjectMapper;

ByteArrayOutputStream baos = new ByteArrayOutputStream();

ObjectMapper mapper = new ObjectMapper();
Root root = ... // some hierarchical object
mapper.writeValue(baos, root);
System.out.println(new String(baos.toByteArray()));

Code Examples

Full Data Binding Example
Full Data Binding Example 2

Generics Handling

To enable generic type information (like "Map<String,Object>"), you have to use TypeReference container. See http://wiki.fasterxml.com/JacksonDataBinding.

Full Data Binding and Generics Example

Annotations

Jackson Annotations

Abstract Class Handling

Abstract Class Handling

Custom Deserializers

Custom Deserializers