com.fasterxml.jackson.jr.ob.api.ValueReader Maven / Gradle / Ivy
Show all versions of jackson-jr-all Show documentation
package com.fasterxml.jackson.jr.ob.api;
import java.io.IOException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.jr.ob.impl.JSONReader;
/**
* API and base class for all "deserializer" implementations used to actually read
* values of Java types from (JSON) input.
*/
public abstract class ValueReader
{
/**
* Type of values this reader will read
*
* @since 2.10
*/
protected final Class _valueType;
protected ValueReader(Class valueType) {
_valueType = valueType;
}
/*
/**********************************************************************
/* Basic API to implement for actual read operations
/**********************************************************************
*/
/**
* Method called to deserialize value of type supported by this reader, using
* given parser. Parser is already positioned to the (first) token
* of the value to read.
*
* @param reader Context object that allows calling other read methods for contained
* values of different types (for example for collection readers).
* @param p Underlying parser used for reading decoded token stream
*/
public abstract Object read(JSONReader reader, JsonParser p) throws IOException;
/**
* Method called to deserialize value of type supported by this reader, using
* given parser. Parser is not yet positioned to the (first) token
* of the value to read and needs to be advanced.
*
* Default implementation simply calls `p.nextToken()` first, then calls
* {#link {@link #read(JSONReader, JsonParser)}, but some implementations
* may decide to implement this differently to use (slightly) more efficient
* accessor in {@link JsonParser}, like {@link JsonParser#nextIntValue(int)}.
*
* @param reader Context object that allows calling other read methods for contained
* values of different types (for example for collection readers).
* @param p Underlying parser used for reading decoded token stream
*/
public Object readNext(JSONReader reader, JsonParser p) throws IOException {
p.nextToken();
return read(reader, p);
}
/*
/**********************************************************************
/* Minimal metadata
/**********************************************************************
*/
/**
* Accessor for non-generic (type-erased) type of values this reader
* produces from input.
*
* @since 2.10
*/
public Class valueType() {
return _valueType;
}
/*
/**********************************************************************
/* Helper methods for sub-classes
/**********************************************************************
*/
/**
* Helper method for getting description of the token parser currently points to,
* for use in descriptions and exception messages.
*/
public static String _tokenDesc(JsonParser p) throws IOException {
return _tokenDesc(p, p.currentToken());
}
/**
* Helper method for getting description of given token
* for use in descriptions and exception messages.
*/
public static String _tokenDesc(JsonParser p, JsonToken t) throws IOException {
if (t == null) {
return "NULL";
}
switch (t) {
case FIELD_NAME:
return "JSON Field name '"+p.currentName()+"'";
case START_ARRAY:
return "JSON Array";
case START_OBJECT:
return "JSON Object";
case VALUE_FALSE:
return "`false`";
case VALUE_NULL:
return "'null'";
case VALUE_NUMBER_FLOAT:
case VALUE_NUMBER_INT:
return "JSON Number";
case VALUE_STRING:
return "JSON String";
case VALUE_TRUE:
return "`true`";
case VALUE_EMBEDDED_OBJECT:
{
final Object value = p.getEmbeddedObject();
if (value == null) {
return "EMBEDDED_OBJECT `null`";
}
return "EMBEDDED_OBJECT of type "+p.getClass().getName();
}
default:
return t.toString();
}
}
}