package org.apache.solr.common.util;import java.io.IOException;import java.io.InputStream;import java.io.Reader;/** * * @since solr 1.2 */public interface ContentStream {  String getName();  String getSourceInfo();  String getContentType();    /**   * @return 数据流大小 或者 <code>null</code>    */  Long getSize(); //如果知道返回大小否则位null    /**   * 获取一个打开的数据流,那么必须负责关闭它.可以考虑这样使用:   * <pre>   *   InputStream stream = stream.getStream();   *   try {   *     // use the stream...   *   }   *   finally {   *     IOUtils.closeQuietly(stream);   *   }   *  </pre>   *     *  为了保证正在运行,只有在第一次时调用<code>getStream()</code> 或者 <code>getReader()</code>,   *  其他调用的运行行为时不明确的.   *   * 注意: 在属性(name, contentType, etc)保证被赋值之前,必须调用<code>getStream()</code> 或者   *  <code>getReader()</code>.数据流只有在该方法调用时才可能懒加载.   */  InputStream getStream() throws IOException;  /**   * 获取一个打开的数据流,那么必须负责关闭它.可以考虑这样使用:   * <pre>   *   Reader reader = stream.getReader();   *   try {   *     // use the reader...   *   }   *   finally {   *     IOUtils.closeQuietly(reader);   *   }   *  </pre>   *      *  为了保证正在运行,只有在第一次时调用<code>getStream()</code> 或者 <code>getReader()</code>,   *  其他调用的运行行为时不明确的.   *   * 注意: 在属性(name, contentType, etc)保证被赋值之前,必须调用<code>getStream()</code> 或者   *  <code>getReader()</code>.数据流只有在该方法调用时才可能懒加载.   */  Reader getReader() throws IOException;}

package org.apache.solr.common.util;import java.io.ByteArrayInputStream;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.Reader;import java.io.StringReader;import java.net.URL;import java.net.URLConnection;import java.util.Locale;/** * 三个ContentStream的具体实现 - 一个 File/URL/String *  * * @since solr 1.2 */public abstract class ContentStreamBase implements ContentStream{  public static final String DEFAULT_CHARSET = "utf-8";    protected String name;  protected String sourceInfo;  protected String contentType;  protected Long size;    //---------------------------------------------------------------------  //---------------------------------------------------------------------  /**   * 从 内容类型字符串中得到字符编码设置,没有的话,返回null   * @param contentType   * @return   */  public static String getCharsetFromContentType( String contentType )  {    if( contentType != null ) {        //获取contentType中"charset="的索引下标      int idx = contentType.toLowerCase(Locale.ROOT).indexOf( "charset=" );      if( idx > 0 ) {        return contentType.substring( idx + "charset=".length() ).trim();      }    }    return null;  }    //------------------------------------------------------------------------  //------------------------------------------------------------------------    /**   * 根据<code>URL</code> 构造<code>ContentStream</code>   *    * 这里使用<code>URLConnection</code>来获得数据流的内容   * @see  URLConnection   */  public static class URLStream extends ContentStreamBase  {    private final URL url;        public URLStream( URL url ) {      this.url = url;       sourceInfo = "url";    }    @Override    public InputStream getStream() throws IOException {      URLConnection conn = this.url.openConnection();            contentType = conn.getContentType();      name = url.toExternalForm();      size = new Long( conn.getContentLength() );      return conn.getInputStream();    }  }    /**   * 根据<code>File</code> 构造<code>ContentStream</code>   */  public static class FileStream extends ContentStreamBase  {    private final File file;        public FileStream( File f ) {      file = f;             contentType = null; // ??      name = file.getName();      size = file.length();      sourceInfo = file.toURI().toString();    }    @Override    public String getContentType() {      if(contentType==null) {        InputStream stream = null;        try {          stream = new FileInputStream(file);          char first = (char)stream.read();          if(first == ‘<‘) {            return "application/xml";          }          if(first == ‘{‘) {            return "application/json";          }        } catch(Exception ex) {        } finally {          if (stream != null) try {            stream.close();          } catch (IOException ioe) {}        }      }      return contentType;    }    @Override    public InputStream getStream() throws IOException {      return new FileInputStream( file );    }  }    /**   * 根据<code>String</code> 构造<code>ContentStream</code>   */  public static class StringStream extends ContentStreamBase  {    private final String str;        public StringStream( String str ) {      this.str = str;             contentType = null;      name = null;      size = new Long( str.length() );      sourceInfo = "string";    }    @Override    public String getContentType() {      if(contentType==null && str.length() > 0) {        char first = str.charAt(0);        if(first == ‘<‘) {          return "application/xml";        }        if(first == ‘{‘) {          return "application/json";        }        // find a comma? for CSV?      }      return contentType;    }    @Override    public InputStream getStream() throws IOException {      return new ByteArrayInputStream( str.getBytes(DEFAULT_CHARSET) );    }    /**     * 如果contentType中没有定义charset编码,则使用StringReader     */    @Override    public Reader getReader() throws IOException {      String charset = getCharsetFromContentType( contentType );      return charset == null         ? new StringReader( str )        : new InputStreamReader( getStream(), charset );    }  }  /**   * 基本的reader 实现. 如果contentType声明了一个charset,   * 则使用charset中的编码,否则使用utf-8.   */  @Override  public Reader getReader() throws IOException {    String charset = getCharsetFromContentType( getContentType() );    return charset == null       ? new InputStreamReader( getStream(), DEFAULT_CHARSET )      : new InputStreamReader( getStream(), charset );  }  //------------------------------------------------------------------  // Getters / Setters for overrideable attributes  //------------------------------------------------------------------  @Override  public String getContentType() {    return contentType;  }  public void setContentType(String contentType) {    this.contentType = contentType;  }  @Override  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  @Override  public Long getSize() {    return size;  }  public void setSize(Long size) {    this.size = size;  }  @Override  public String getSourceInfo() {    return sourceInfo;  }  public void setSourceInfo(String sourceInfo) {    this.sourceInfo = sourceInfo;  }    /**   *  根据<code>File</code> 构造<code>ContentStream</code>   */  public static class ByteArrayStream extends ContentStreamBase  {    private final byte[] bytes;        public ByteArrayStream( byte[] bytes, String source ) {      this.bytes = bytes;             this.contentType = null;      name = source;      size = new Long(bytes.length);      sourceInfo = source;    }    @Override    public InputStream getStream() throws IOException {      return new ByteArrayInputStream( bytes );    }  }  }