Java tutorial
/** * Copyright (c) 2010-2019 Contributors to the openHAB project * * See the NOTICE file(s) distributed with this work for additional * information. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License 2.0 which is available at * http://www.eclipse.org/legal/epl-2.0 * * SPDX-License-Identifier: EPL-2.0 */ package org.openhab.io.transport.modbus.json; import java.util.Collection; import java.util.Deque; import java.util.LinkedList; import java.util.concurrent.atomic.AtomicBoolean; import org.apache.commons.lang.NotImplementedException; import org.eclipse.jdt.annotation.NonNullByDefault; import org.eclipse.jdt.annotation.Nullable; import org.openhab.io.transport.modbus.BasicBitArray; import org.openhab.io.transport.modbus.ModbusRegister; import org.openhab.io.transport.modbus.BasicModbusRegisterArray; import org.openhab.io.transport.modbus.BasicModbusRegister; import org.openhab.io.transport.modbus.BasicModbusWriteCoilRequestBlueprint; import org.openhab.io.transport.modbus.ModbusWriteFunctionCode; import org.openhab.io.transport.modbus.BasicModbusWriteRegisterRequestBlueprint; import org.openhab.io.transport.modbus.ModbusWriteRequestBlueprint; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonParser; /** * Utilities for converting JSON to {@link ModbusWriteRequestBlueprint} * * * @author Sami Salonen - Initial contribution */ @NonNullByDefault public final class WriteRequestJsonUtilities { /** * Constant for the function code key in the JSON */ public static final String JSON_FUNCTION_CODE = "functionCode"; /** * Constant for the write address key in the JSON */ public static final String JSON_ADDRESS = "address"; /** * Constant for the value key in the JSON */ public static final String JSON_VALUE = "value"; /** * Constant for the maxTries key in the JSON */ public static final String JSON_MAX_TRIES = "maxTries"; /** * Default maxTries when it has not been specified */ public static final int DEFAULT_MAX_TRIES = 3; private static final JsonParser PARSER = new JsonParser(); private WriteRequestJsonUtilities() { throw new NotImplementedException(); } /** * Parse JSON string to collection of {@link ModbusWriteRequestBlueprint} * * JSON string should represent a JSON array, with JSON objects. Each JSON object represents a write request. The * JSON object must have the following keys * - functionCode: numeric function code * - address: reference or start address of the write * - value: array of data to be written. Use zero and one when writing coils. With registers, each number * corresponds to register's 16 bit data. * - maxTries: number of tries with the write in case of errors * * * @param unitId unit id for the constructed {@link ModbusWriteRequestBlueprint} * @param jsonString json to be parsed in string format * @return collection of {@link ModbusWriteRequestBlueprint} representing the json * @throws IllegalArgumentException in case of unexpected function codes * @throws IllegalStateException in case of parsing errors and unexpected json structure * * @see WriteRequestJsonUtilities.JSON_FUNCTION_CODE * @see WriteRequestJsonUtilities.JSON_ADDRESS * @see WriteRequestJsonUtilities.JSON_VALUE * @see WriteRequestJsonUtilities.JSON_MAX_TRIES */ public static Collection<ModbusWriteRequestBlueprint> fromJson(int unitId, String jsonString) { JsonArray jsonArray = PARSER.parse(jsonString).getAsJsonArray(); if (jsonArray.size() == 0) { return new LinkedList<>(); } Deque<ModbusWriteRequestBlueprint> writes = new LinkedList<>(); jsonArray.forEach(writeElem -> { writes.add(constructBluerint(unitId, writeElem)); }); return writes; } private static ModbusWriteRequestBlueprint constructBluerint(int unitId, JsonElement arrayElement) { final JsonObject writeObject; try { writeObject = arrayElement.getAsJsonObject(); } catch (IllegalStateException e) { throw new IllegalStateException("JSON array contained something else than a JSON object!", e); } @Nullable JsonElement functionCode = writeObject.get(JSON_FUNCTION_CODE); @Nullable JsonElement address = writeObject.get(JSON_ADDRESS); @Nullable JsonElement maxTries = writeObject.get(JSON_MAX_TRIES); @Nullable JsonArray valuesElem; try { valuesElem = writeObject.get(JSON_VALUE).getAsJsonArray(); } catch (IllegalStateException e) { throw new IllegalStateException(String.format("JSON object '%s' is not an JSON array!", JSON_VALUE), e); } return constructBluerint(unitId, functionCode, address, maxTries, valuesElem); } private static ModbusWriteRequestBlueprint constructBluerint(int unitId, @Nullable JsonElement functionCodeElem, @Nullable JsonElement addressElem, @Nullable JsonElement maxTriesElem, @Nullable JsonArray valuesElem) { int functionCodeNumeric; if (functionCodeElem == null || functionCodeElem.isJsonNull()) { throw new IllegalStateException(String.format("Value for '%s' is invalid", JSON_FUNCTION_CODE)); } try { functionCodeNumeric = functionCodeElem.getAsInt(); } catch (ClassCastException | IllegalStateException e) { throw new IllegalStateException(String.format("Value for '%s' is invalid", JSON_FUNCTION_CODE), e); } ModbusWriteFunctionCode functionCode = ModbusWriteFunctionCode.fromFunctionCode(functionCodeNumeric); int address; if (addressElem == null || addressElem.isJsonNull()) { throw new IllegalStateException(String.format("Value for '%s' is invalid", JSON_ADDRESS)); } try { address = addressElem.getAsInt(); } catch (ClassCastException | IllegalStateException e) { throw new IllegalStateException(String.format("Value for '%s' is invalid", JSON_ADDRESS), e); } int maxTries; if (maxTriesElem == null || maxTriesElem.isJsonNull()) { // Go with default maxTries = DEFAULT_MAX_TRIES; } else { try { maxTries = maxTriesElem.getAsInt(); } catch (ClassCastException | IllegalStateException e) { throw new IllegalStateException(String.format("Value for '%s' is invalid", JSON_MAX_TRIES), e); } } if (valuesElem == null || valuesElem.isJsonNull()) { throw new IllegalArgumentException(String.format("Expecting non-null value, got: %s", valuesElem)); } AtomicBoolean writeSingle = new AtomicBoolean(false); switch (functionCode) { case WRITE_COIL: writeSingle.set(true); if (valuesElem.size() != 1) { throw new IllegalArgumentException(String .format("Expecting single value with functionCode=%s, got: %d", functionCode, valuesElem)); } // fall-through to WRITE_MULTIPLE_COILS case WRITE_MULTIPLE_COILS: if (valuesElem.size() == 0) { throw new IllegalArgumentException("Must provide at least one coil"); } BasicBitArray bits = new BasicBitArray(valuesElem.size()); for (int i = 0; i < valuesElem.size(); i++) { bits.setBit(i, valuesElem.get(i).getAsInt() != 0); } return new BasicModbusWriteCoilRequestBlueprint(unitId, address, bits, !writeSingle.get(), maxTries); case WRITE_SINGLE_REGISTER: writeSingle.set(true); if (valuesElem.size() != 1) { throw new IllegalArgumentException(String .format("Expecting single value with functionCode=%s, got: %d", functionCode, valuesElem)); } // fall-through to WRITE_MULTIPLE_REGISTERS case WRITE_MULTIPLE_REGISTERS: { ModbusRegister[] registers = new ModbusRegister[valuesElem.size()]; if (registers.length == 0) { throw new IllegalArgumentException("Must provide at least one register"); } for (int i = 0; i < valuesElem.size(); i++) { registers[i] = new BasicModbusRegister(valuesElem.get(i).getAsInt()); } return new BasicModbusWriteRegisterRequestBlueprint(unitId, address, new BasicModbusRegisterArray(registers), !writeSingle.get(), maxTries); } default: throw new IllegalArgumentException("Unknown function code"); } } }