io.datatree.dom.TreeWriterRegistry Maven / Gradle / Ivy
/**
* This software is licensed under the Apache 2 license, quoted below.
*
* Copyright 2017 Andras Berkes [[email protected]]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.datatree.dom;
import java.util.Collections;
import java.util.HashMap;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import io.datatree.dom.builtin.JsonBuiltin;
/**
* Registry of TreeWriter instances.
*
* @author Andras Berkes [[email protected]]
*/
public class TreeWriterRegistry {
// --- DEFAULT OUTPUT FORMAT ---
public static final String JSON = "json";
// --- WRITER REGISTRY ---
private static final ConcurrentHashMap writers = new ConcurrentHashMap();
// --- DEPENDENCY SAMPLES ---
private static final HashMap dependencySamples = new HashMap<>();
// --- DEFAULT JSON WRITER ---
private static TreeWriter cachedJsonWriter = getWriter(JSON, false);
// --- PRIVATE CONSTRUCTOR ---
private TreeWriterRegistry() {
}
// --- SET THE DEFAULT WRITER FOR FORMAT ---
/**
* Binds the given TreeWriter instance to the specified data format.
*
* @param format
* name of the format (eg. "json", "xml", "csv", etc.)
* @param writer
* TreeWriter instance for generating the specified format
*/
public static final void setWriter(String format, TreeWriter writer) {
String key = format.toLowerCase();
writers.put(key, writer);
if (JSON.equals(key)) {
cachedJsonWriter = writer;
}
}
// --- DEREGISTER WRITER ---
/**
* Deregisters the given format from the registry.
*
* @param format
* name of the format (eg. "custom", "csv", etc.)
*/
public static final void removeWriter(String format) {
String key = format.toLowerCase();
if (JSON.equals(key)) {
throw new IllegalArgumentException("Unable to delete the default JSON writer!");
}
writers.remove(key);
}
// --- GET WRITER BY FORMAT NAME ---
/**
* Returns the TreeWriter instance to which the specified format is mapped.
*
* @param format
* name of the format (eg. "json", "xml", etc.)
*
* @return TreeWriter instance
*/
public static final TreeWriter getWriter(String format) {
return getWriter(format, true);
}
// --- FORMAT INFO ---
/**
* Check the availability of the specified format.
*
* @param format
* name of the format (eg. "json", "xml", etc.)
*
* @return returns true, if the proper writer is installed
*/
public static final boolean isAvailable(String format) {
return getWriter(format, false).getFormat().equalsIgnoreCase(format);
}
/**
* Returns the supported format names.
*
* @return Set of format names (eg. "json", "xml", etc.)
*/
public static final Set getSupportedFormats() {
return Collections.unmodifiableSet(writers.keySet());
}
/**
* Get detected deserializers by format name.
*
* @param format
* name of the format (eg. "json", "xml", etc.)
*
* @return Set of class names (eg. "io.datatree.dom.builtin.JsonBuiltin")
*/
public static final Set getWritersByFormat(String format) {
return PackageScanner.getWritersByFormat(format);
}
// --- FACTORY FINDER METHOD ---
private static final TreeWriter getWriter(String format, boolean throwException) {
TreeWriter writer;
if (format == null) {
writer = cachedJsonWriter;
} else {
String key = format.toLowerCase();
if (JSON.equals(key)) {
writer = cachedJsonWriter;
} else {
writer = writers.get(key);
}
}
if (writer != null) {
return writer;
}
// Searching writer class in system properties... Samples:
//
// -Ddatatree.json.writer=io.datatree.writers.JacksonjsonWriter
// -Ddatatree.xml.writer=io.datatree.writers.BuiltinxmlWriter
// -Ddatatree.yaml.writer=io.datatree.writers.SnakeyamlWriter
// -Ddatatree.csv.writer=your.csv.writer.ClassName
// -Ddatatree.properties.writer=your.properties.writer.ClassName
//
// ...and to use your "custom" format:
//
// -Ddatatree.custom.writer=your.custom.writer.ClassName
// String out = node.toString("custom");
//
String propertyName = "datatree." + format + ".writer";
try {
String className = System.getProperty(propertyName);
if (className == null || className.isEmpty()) {
className = PackageScanner.findByFormat(format, false);
}
if (className == null || className.isEmpty()) {
throw new IllegalArgumentException("System Property \"" + propertyName + "\" not found! "
+ "This property defines a custom writer class for the \"" + format + "\" format.");
}
writer = (TreeWriter) Class.forName(className).newInstance();
writers.put(format, writer);
return writer;
} catch (Throwable cause) {
if (throwException) {
suggestDependency(format);
cause.printStackTrace();
throw new IllegalArgumentException("Unable to create writer for format \"" + format + "\"! Set the -D"
+ propertyName + "=package.WriterClass initial parameter to specify the proper writer class.",
cause);
}
}
return new JsonBuiltin();
}
// --- DEPENDENCY HELPER ---
static {
addSample("yaml", "org.yaml", "snakeyaml", "1.23");
addSample("csv", "net.sf.opencsv", "opencsv", "2.3");
addSample("xstream", "xstream", "xstream", "1.2.2");
addSample("toml", "com.moandjiezana.toml", "toml4j", "0.7.2");
addSample("smile", "com.fasterxml.jackson.dataformat", "jackson-dataformat-smile", "2.9.7");
addSample("cbor", "com.fasterxml.jackson.dataformat", "jackson-dataformat-cbor", "2.9.7");
addSample("bson", "de.undercouch", "bson4jackson", "2.9.0");
addSample("msgpack", "org.msgpack", "msgpack", "0.6.12");
addSample("ion", "software.amazon.ion", "ion-java", "1.2.0");
addSample("kryo", "com.esotericsoftware", "kryo", "4.0.1");
}
private static final void addSample(String format, String group, String name, String version) {
dependencySamples.put(format, new String[] { group, name, version });
}
static final void suggestDependency(String format) {
if (format == null || format.isEmpty()) {
return;
}
String[] samples = dependencySamples.get(format.contains("pack") ? "msgpack" : format);
if (samples == null) {
return;
}
System.err.println("It looks like you are missing some dependencies!");
System.err.println("Sample Maven dependency:");
System.err.println();
System.err.println("");
System.err.println(" " + samples[0] + " ");
System.err.println(" " + samples[1] + " ");
System.err.println(" " + samples[2] + " ");
System.err.println(" ");
System.err.println();
System.err.println("Sample Gradle dependency:");
System.err.println();
System.err.println(
"compile group: '" + samples[0] + "', name: '" + samples[1] + "', version: '" + samples[2] + "'");
System.err.println();
System.err.println("...or download the JAR from https://mvnrepository.com/artifact/" + samples[0] + "/" + samples[1]);
System.err.println();
}
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