com.hbztc.middleware.util.Utf8StringHttpMessageConverter.java Source code

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Here is the source code for com.hbztc.middleware.util.Utf8StringHttpMessageConverter.java

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package com.hbztc.middleware.util;

/*
 * Copyright 2002-2012 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
 *
 *      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.
 */

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.util.FileCopyUtils;

/**
 * Implementation of {@link HttpMessageConverter} that can read and write
 * strings.
 * 
 * <p>
 * By default, this converter supports all media types (
 * <code>&#42;&#47;&#42;</code>), and writes with a {@code Content-Type} of
 * {@code text/plain}. This can be overridden by setting the
 * {@link #setSupportedMediaTypes supportedMediaTypes} property.
 * 
 * @author Arjen Poutsma
 * @since 3.0
 */
public class Utf8StringHttpMessageConverter extends AbstractHttpMessageConverter<String> {

    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

    private final Charset defaultCharset;

    private final List<Charset> availableCharsets;

    private boolean writeAcceptCharset = true;

    /**
     * A default constructor that uses {@code "ISO-8859-1"} as the default
     * charset.
     * 
     * @see #StringHttpMessageConverter(Charset)
     */
    public Utf8StringHttpMessageConverter() {
        this(DEFAULT_CHARSET);
    }

    /**
     * A constructor accepting a default charset to use if the requested content
     * type does not specify one.
     */
    public Utf8StringHttpMessageConverter(Charset defaultCharset) {
        super(new MediaType("text", "plain", defaultCharset), MediaType.ALL);
        this.defaultCharset = defaultCharset;
        this.availableCharsets = new ArrayList<Charset>(Charset.availableCharsets().values());
    }

    /**
     * Indicates whether the {@code Accept-Charset} should be written to any
     * outgoing request.
     * <p>
     * Default is {@code true}.
     */
    public void setWriteAcceptCharset(boolean writeAcceptCharset) {
        this.writeAcceptCharset = writeAcceptCharset;
    }

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

    @Override
    protected String readInternal(Class<? extends String> clazz, HttpInputMessage inputMessage) throws IOException {
        Charset charset = getContentTypeCharset(inputMessage.getHeaders().getContentType());
        return FileCopyUtils.copyToString(new InputStreamReader(inputMessage.getBody(), charset));
    }

    @Override
    protected Long getContentLength(String s, MediaType contentType) {
        Charset charset = getContentTypeCharset(contentType);
        try {
            return (long) s.getBytes(charset.name()).length;
        } catch (UnsupportedEncodingException ex) {
            // should not occur
            throw new IllegalStateException(ex);
        }
    }

    @Override
    protected void writeInternal(String s, HttpOutputMessage outputMessage) throws IOException {
        if (this.writeAcceptCharset) {
            outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
        }
        Charset charset = getContentTypeCharset(outputMessage.getHeaders().getContentType());
        FileCopyUtils.copy(s, new OutputStreamWriter(outputMessage.getBody(), charset));
    }

    /**
     * Return the list of supported {@link Charset}.
     * <p>
     * By default, returns {@link Charset#availableCharsets()}. Can be
     * overridden in subclasses.
     * 
     * @return the list of accepted charsets
     */
    protected List<Charset> getAcceptedCharsets() {
        return this.availableCharsets;
    }

    private Charset getContentTypeCharset(MediaType contentType) {
        if (contentType != null && contentType.getCharSet() != null) {
            return contentType.getCharSet();
        } else {
            return this.defaultCharset;
        }
    }
}