com.googlecode.jsonrpc4j.DefaultExceptionResolver.java Source code

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Here is the source code for com.googlecode.jsonrpc4j.DefaultExceptionResolver.java

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/*
The MIT License (MIT)
    
Copyright (c) 2014 jsonrpc4j
    
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
    
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
    
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
 */

package com.googlecode.jsonrpc4j;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.fasterxml.jackson.databind.node.ObjectNode;

/**
 * Default implementation of the {@link ExceptionResolver}
 * interface that attemps to re-throw the same exception
 * that was thrown by the server.  This always returns
 * a {@link Throwable}.
 *
 */
public class DefaultExceptionResolver implements ExceptionResolver {

    private static final Logger LOGGER = Logger.getLogger(DefaultExceptionResolver.class.getName());

    public static final DefaultExceptionResolver INSTANCE = new DefaultExceptionResolver();

    /**
     * {@inheritDoc}
     */
    public Throwable resolveException(ObjectNode response) {

        // get the error object
        ObjectNode errorObject = ObjectNode.class.cast(response.get("error"));

        // bail if we don't have a data object
        if (!errorObject.has("data") || errorObject.get("data").isNull() || !errorObject.get("data").isObject()) {
            return createJsonRpcClientException(errorObject);
        }

        // get the data object
        ObjectNode dataObject = ObjectNode.class.cast(errorObject.get("data"));

        // bail if it's not the expected format
        if (!dataObject.has("exceptionTypeName") || dataObject.get("exceptionTypeName") == null
                || dataObject.get("exceptionTypeName").isNull()
                || !dataObject.get("exceptionTypeName").isTextual()) {
            return createJsonRpcClientException(errorObject);
        }

        // get values
        String exceptionTypeName = dataObject.get("exceptionTypeName").asText();
        String message = dataObject.has("message") && dataObject.get("message").isTextual()
                ? dataObject.get("message").asText()
                : null;

        // create it
        Throwable ret = null;
        try {
            ret = createThrowable(exceptionTypeName, message);
        } catch (Exception e) {
            LOGGER.log(Level.WARNING, "Unable to create throwable", e);
        }

        // if we can't create it, create a default exception
        if (ret == null) {
            ret = createJsonRpcClientException(errorObject);
        }

        // return it
        return ret;
    }

    /**
     * Creates a {@link JsonRpcClientException} from the given
     * {@link ObjectNode}.
     * @param errorObject the error object
     * @return the exception
     */
    private JsonRpcClientException createJsonRpcClientException(ObjectNode errorObject) {
        int code = errorObject.has("code") ? errorObject.get("code").asInt() : 0;
        return new JsonRpcClientException(code, errorObject.get("message").asText(), errorObject.get("data"));
    }

    /**
     * Attempts to create an {@link Throwable} of the given type
     * with the given message.  For this method to create a
     * {@link Throwable} it must have either a default (no-args)
     * constructor or a  constructor that takes a {@code String}
     * as the message name.  null is returned if a {@link Throwable}
     * can't be created.
     * @param typeName the java type name (class name)
     * @param message the message
     * @return the throwable
     * @throws InvocationTargetException 
     * @throws IllegalAccessException 
     * @throws InstantiationException 
     * @throws IllegalArgumentException 
     */
    private Throwable createThrowable(String typeName, String message) throws IllegalArgumentException,
            InstantiationException, IllegalAccessException, InvocationTargetException {

        // load class
        Class<?> clazz = null;
        try {
            clazz = Class.forName(typeName);
        } catch (Exception e) {
            LOGGER.warning("Unable to load Throwable class " + typeName);
            return null;
        }

        // get Throwable clazz
        if (!Throwable.class.isAssignableFrom(clazz)) {
            LOGGER.warning("Type does not inherit from Throwable" + clazz.getName());
            return null;
        }
        @SuppressWarnings("unchecked")
        Class<? extends Throwable> tClazz = (Class<? extends Throwable>) clazz;

        // get the two constructors that we can use
        Constructor<? extends Throwable> defaultCtr = null;
        Constructor<? extends Throwable> messageCtr = null;
        try {
            defaultCtr = tClazz.getConstructor();
        } catch (Throwable t) {
            /* eat it */ }
        try {
            messageCtr = tClazz.getConstructor(String.class);
        } catch (Throwable t) {
            /* eat it */ }

        // messageCtr
        if (message != null && messageCtr != null) {
            return messageCtr.newInstance(message);
        } else if (message != null && defaultCtr != null) {
            LOGGER.warning("Unable to invoke message constructor for " + clazz.getName());
            return defaultCtr.newInstance();

            // defaultCtr
        } else if (message == null && defaultCtr != null) {
            return defaultCtr.newInstance();
        } else if (message == null && messageCtr != null) {
            LOGGER.warning("Passing null message to message constructor for " + clazz.getName());
            return messageCtr.newInstance((String) null);

            // can't find a constructor
        } else {
            LOGGER.warning("Unable to find a suitable constructor for " + clazz.getName());
            return null;
        }

    }
}