com.dkfqs.tools.json

Class SimpleCachedJsonValueExtractor

java.lang.Object

com.dkfqs.tools.json.SimpleCachedJsonValueExtractor

public class SimpleCachedJsonValueExtractor
extends java.lang.Object

Extract simple single Json values from cached Json data by applying simple Json queries.
This class precalculate all results of simple queries in a cache in order to reduce the CPU load and increase the speed when multiple simple queries are made.

Programming Example:

String jsonSource = "{\"testArray\":[1,2,3, {\"A\":5,\"B\":7},\"X\"], \"tail\":9}";
String simpleQuery = "testArray.[3].A";
SimpleCachedJsonValueExtractor cachedJsonValueExtractor = new SimpleCachedJsonValueExtractor(jsonSource);
if (cachedJsonValueExtractor.containsQuery(simpleQuery)) {
    JsonValue queryResult = cachedJsonValueExtractor.getQueryResult(simpleQuery);
    if (queryResult == null) {
        System.out.println("Query Result = Json null value");
    }
    else {
        System.out.println("Query Result = " + queryResult.toString()); // 5
    }
 }
 else {
     System.out.println("[No match found]");
 }

 

Constructor Summary

Constructors

Constructor and Description
SimpleCachedJsonValueExtractor(java.io.Reader jsonReader) Create a new instance from a Json Reader and initialize the cache.
SimpleCachedJsonValueExtractor(java.lang.String jsonSource) Create a new instance from a Json String and initialize the cache.

Method Summary

Modifier and Type	Method and Description
boolean	containsQuery(java.lang.String simpleQuery) Get if the cache contains a result of a simple query.
JsonValue	getQueryResult(java.lang.String simpleQuery) Get the simple Json value (String, long, boolean or null).

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SimpleCachedJsonValueExtractor

public SimpleCachedJsonValueExtractor(java.lang.String jsonSource)

Create a new instance from a Json String and initialize the cache.

Parameters:

jsonSource - a String containing the Json data

Throws:

java.lang.IllegalArgumentException - if the root of the Json data is not an Object or Array

SimpleCachedJsonValueExtractor

public SimpleCachedJsonValueExtractor(java.io.Reader jsonReader)
                               throws java.io.IOException

Create a new instance from a Json Reader and initialize the cache.

Parameters:

jsonReader - a Reader for the Json data

Throws:

java.lang.IllegalArgumentException - if the root of the Json data is not an Object or Array

java.io.IOException - if somewhat fails.

Method Detail

containsQuery

public boolean containsQuery(java.lang.String simpleQuery)

Get if the cache contains a result of a simple query.

Parameters:

simpleQuery - the simple query. Examples: "[0].datapoints.[2].[1]", "customers.person.name"

Returns:

true if the cache contains a result of a simple query

getQueryResult

public JsonValue getQueryResult(java.lang.String simpleQuery)

Get the simple Json value (String, long, boolean or null).

Parameters:

simpleQuery - the simple query. Examples: "[0].datapoints.[2].[1]", "customers.person.name"

Returns:

the simple Json value (String, long, boolean or null)