HttpClient4.3学习之EntityUtils对象

        最近使用HttpClient4.3开源包，发现了EntityUtils这个对象，EntityUtils对象是org.apache.http.util下的一个工具类，用官方的解释是为HttpEntity对象提供的静态帮助类，其常用的几个方法如下：

        consume()方法;

        consumeQuietly(HttpEntity)方法

        toByteArray(final HttpEntity entity)方法

        最主要的就是consume()这个方法，其功能就是关闭HttpEntity是的流，如果手动关闭了InputStream instream = entity.getContent();这个流，也可以不调用这个方法。看看了其源码就知道了：

 

public final class EntityUtils {

    private EntityUtils() {
    }
    public static void consumeQuietly(final HttpEntity entity) {
        try {
          consume(entity);
        } catch (final IOException ignore) {
        }
    }
    public static void consume(final HttpEntity entity) throws IOException {
        if (entity == null) {
            return;
        }
        if (entity.isStreaming()) {
            final InputStream instream = entity.getContent();
            if (instream != null) {
                instream.close();
            }
        }
    }


    public static void updateEntity(
            final HttpResponse response, final HttpEntity entity) throws IOException {
        Args.notNull(response, "Response");
        consume(response.getEntity());
        response.setEntity(entity);
    }
    public static byte[] toByteArray(final HttpEntity entity) throws IOException {
        Args.notNull(entity, "Entity");
        final InputStream instream = entity.getContent();
        if (instream == null) {
            return null;
        }
        try {
            Args.check(entity.getContentLength() <= Integer.MAX_VALUE,
                    "HTTP entity too large to be buffered in memory");
            int i = (int)entity.getContentLength();
            if (i < 0) {
                i = 4096;
            }
            final ByteArrayBuffer buffer = new ByteArrayBuffer(i);
            final byte[] tmp = new byte[4096];
            int l;
            while((l = instream.read(tmp)) != -1) {
                buffer.append(tmp, 0, l);
            }
            return buffer.toByteArray();
        } finally {
            instream.close();
        }
    }

    @Deprecated
    public static String getContentCharSet(final HttpEntity entity) throws ParseException {
        Args.notNull(entity, "Entity");
        String charset = null;
        if (entity.getContentType() != null) {
            final HeaderElement values[] = entity.getContentType().getElements();
            if (values.length > 0) {
                final NameValuePair param = values[0].getParameterByName("charset");
                if (param != null) {
                    charset = param.getValue();
                }
            }
        }
        return charset;
    }


    @Deprecated
    public static String getContentMimeType(final HttpEntity entity) throws ParseException {
        Args.notNull(entity, "Entity");
        String mimeType = null;
        if (entity.getContentType() != null) {
            final HeaderElement values[] = entity.getContentType().getElements();
            if (values.length > 0) {
                mimeType = values[0].getName();
            }
        }
        return mimeType;
    }

    public static String toString(
            final HttpEntity entity, final Charset defaultCharset) throws IOException, ParseException {
        Args.notNull(entity, "Entity");
        final InputStream instream = entity.getContent();
        if (instream == null) {
            return null;
        }
        try {
            Args.check(entity.getContentLength() <= Integer.MAX_VALUE,
                    "HTTP entity too large to be buffered in memory");
            int i = (int)entity.getContentLength();
            if (i < 0) {
                i = 4096;
            }
            Charset charset = null;
            try {
                final ContentType contentType = ContentType.get(entity);
                if (contentType != null) {
                    charset = contentType.getCharset();
                }
            } catch (final UnsupportedCharsetException ex) {
                throw new UnsupportedEncodingException(ex.getMessage());
            }
            if (charset == null) {
                charset = defaultCharset;
            }
            if (charset == null) {
                charset = HTTP.DEF_CONTENT_CHARSET;
            }
            final Reader reader = new InputStreamReader(instream, charset);
            final CharArrayBuffer buffer = new CharArrayBuffer(i);
            final char[] tmp = new char[1024];
            int l;
            while((l = reader.read(tmp)) != -1) {
                buffer.append(tmp, 0, l);
            }
            return buffer.toString();
        } finally {
            instream.close();
        }
    }


    public static String toString(
            final HttpEntity entity, final String defaultCharset) throws IOException, ParseException {
        return toString(entity, defaultCharset != null ? Charset.forName(defaultCharset) : null);
    }
    public static String toString(final HttpEntity entity)
        throws IOException, ParseException {
        return toString(entity, (Charset)null);
    }
}