org.springframework.messaging.converter.StringMessageConverter.java Source code

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Here is the source code for org.springframework.messaging.converter.StringMessageConverter.java

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/*
 * Copyright 2002-2017 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.messaging.converter;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;

/**
 * A {@link MessageConverter} that supports MIME type "text/plain" with the
 * payload converted to and from a String.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class StringMessageConverter extends AbstractMessageConverter {

    private final Charset defaultCharset;

    public StringMessageConverter() {
        this(StandardCharsets.UTF_8);
    }

    public StringMessageConverter(Charset defaultCharset) {
        super(new MimeType("text", "plain", defaultCharset));
        Assert.notNull(defaultCharset, "Default Charset must not be null");
        this.defaultCharset = defaultCharset;
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        return (String.class == clazz);
    }

    @Override
    protected Object convertFromInternal(Message<?> message, Class<?> targetClass,
            @Nullable Object conversionHint) {
        Charset charset = getContentTypeCharset(getMimeType(message.getHeaders()));
        Object payload = message.getPayload();
        return (payload instanceof String ? payload : new String((byte[]) payload, charset));
    }

    @Override
    @Nullable
    protected Object convertToInternal(Object payload, @Nullable MessageHeaders headers,
            @Nullable Object conversionHint) {

        if (byte[].class == getSerializedPayloadClass()) {
            Charset charset = getContentTypeCharset(getMimeType(headers));
            payload = ((String) payload).getBytes(charset);
        }
        return payload;
    }

    private Charset getContentTypeCharset(@Nullable MimeType mimeType) {
        if (mimeType != null && mimeType.getCharset() != null) {
            return mimeType.getCharset();
        } else {
            return this.defaultCharset;
        }
    }

}