com.facebook.presto.jdbc.internal.jackson.databind.package-info Maven / Gradle / Ivy
/**
Basic data binding (mapping) functionality that
allows for reading JSON content into Java Objects (POJOs)
and JSON Trees ({@link com.facebook.presto.jdbc.internal.jackson.databind.JsonNode}), as well as
writing Java Objects and trees as JSON.
Reading and writing (as well as related additional functionality) is accessed through
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper},
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectReader} and
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectWriter}
classes.
In addition to reading and writing JSON content, it is also possible to use the
general databinding functionality for many other data formats, using
Jackson extension modules that provide such support: if so, you typically
simply construct an {@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper} with
different underlying streaming parser, generator implementation.
The main starting point for operations is {@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper},
which can be used either directly (via multiple overloaded
readValue,
readTree,
writeValue and
writeTree methods, or it can be used as a configurable factory for constructing
fully immutable, thread-safe and reusable {@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectReader}
and {@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectWriter} objects.
In addition to simple reading and writing of JSON as POJOs or JSON trees (represented as
{@link com.facebook.presto.jdbc.internal.jackson.databind.JsonNode}, and configurability needed to change aspects
of reading/writing, mapper contains additional functionality such as:
- Value conversions using {@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper#convertValue(Object, Class)},
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper#valueToTree(Object)} and
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper#treeToValue(com.facebook.presto.jdbc.internal.jackson.core.TreeNode, Class)} methods.
- Type introspection needed for things like generation of Schemas (like JSON Schema, Avro Schema, or protoc
definitions), using {@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper#acceptJsonFormatVisitor(Class, com.facebook.presto.jdbc.internal.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper)}
(note: actual handles are usually provided by various Jackson modules: mapper simply initiates calling of
callbacks, based on serializers registered)
Simplest usage is of form:
final ObjectMapper mapper = new ObjectMapper(); // can use static singleton, inject: just make sure to reuse!
MyValue value = new MyValue();
// ... and configure
File newState = new File("my-stuff.json");
mapper.writeValue(newState, value); // writes JSON serialization of MyValue instance
// or, read
MyValue older = mapper.readValue(new File("my-older-stuff.json"), MyValue.class);
// Or if you prefer JSON Tree representation:
JsonNode root = mapper.readTree(newState);
// and find values by, for example, using a {@link com.facebook.presto.jdbc.internal.jackson.core.JsonPointer} expression:
int age = root.at("/personal/age").getValueAsInt();
For more usage, refer to
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectMapper},
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectReader} and
{@link com.facebook.presto.jdbc.internal.jackson.databind.ObjectWriter}
Javadocs.
*/
package com.facebook.presto.jdbc.internal.jackson.databind;