org.apache.solr.common.util.ContentStream.java及其实现类
org.apache.solr.common.util.ContentStream.java 主要是获取文件,URL,字节数组,字符串等的数据流.主要方法又InputStream getStream()和 Reader getReader().
其实现类:org.apache.solr.common.util.ContentStreamBase.java为抽象类.以下有URLStream.java,FileStream.java,StringStream.java,ByteArrayStream.java四个实现类.分别针对URL,文件,字符串,字节数组.
接口:ContentStream.java
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; }
抽象类:ContentStreamBase.java 及其实现类URLStream.java,FileStream.java,StringStream.java,ByteArrayStream.java
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 ); } } }
