Java：将字符串列表作为InputStream访问

是否有任何方式InputStream包装UTF-8 String列表？ 我想做的事情如下：

 InputStream in = new XyzInputStream( List lines ) 

Answer 1

您可以将所有行连接在一起以创建String，然后使用String#getBytes将其转换为字节数组，并将其传递给ByteArrayInputStream 。 然而，这不是最有效的方法。

Answer 2

您可以从ByteArrayOutputStream读取，并且可以使用ByteArrayInputStream创建源byte[]数组。

所以按如下方式创建数组：

  List source = new ArrayList(); source.add("one"); source.add("two"); source.add("three"); ByteArrayOutputStream baos = new ByteArrayOutputStream(); for (String line : source) { baos.write(line.getBytes()); } byte[] bytes = baos.toByteArray(); 

阅读它就像这样简单：

  InputStream in = new ByteArrayInputStream(bytes); 

或者，根据您要做的事情， StringReader可能会更好。

Answer 3

简而言之，不，没有办法使用现有的JDK类来实现这一点。 但是，您可以实现从字符串列表中读取的自己的InputStream 。

编辑：Dave Web上面有一个答案，我认为这是要走的路。 如果你需要一个可重用的类，那么这样的事情可能会：

public class StringsInputStream> extends InputStream { private ByteArrayInputStream bais = null; public StringsInputStream(final T strings) throws IOException { ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); for (String line : strings) { outputStream.write(line.getBytes()); } bais = new ByteArrayInputStream(outputStream.toByteArray()); } @Override public int read() throws IOException { return bais.read(); } @Override public int read(byte[] b) throws IOException { return bais.read(b); } @Override public int read(byte[] b, int off, int len) throws IOException { return bais.read(b, off, len); } @Override public long skip(long n) throws IOException { return bais.skip(n); } @Override public int available() throws IOException { return bais.available(); } @Override public void close() throws IOException { bais.close(); } @Override public synchronized void mark(int readlimit) { bais.mark(readlimit); } @Override public synchronized void reset() throws IOException { bais.reset(); } @Override public boolean markSupported() { return bais.markSupported(); } public static void main(String[] args) throws Exception { List source = new ArrayList(); source.add("foo "); source.add("bar "); source.add("baz"); StringsInputStream> in = new StringsInputStream>(source); int read = in.read(); while (read != -1) { System.out.print((char) read); read = in.read(); } } }
public class StringsInputStream> extends InputStream { private ByteArrayInputStream bais = null; public StringsInputStream(final T strings) throws IOException { ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); for (String line : strings) { outputStream.write(line.getBytes()); } bais = new ByteArrayInputStream(outputStream.toByteArray()); } @Override public int read() throws IOException { return bais.read(); } @Override public int read(byte[] b) throws IOException { return bais.read(b); } @Override public int read(byte[] b, int off, int len) throws IOException { return bais.read(b, off, len); } @Override public long skip(long n) throws IOException { return bais.skip(n); } @Override public int available() throws IOException { return bais.available(); } @Override public void close() throws IOException { bais.close(); } @Override public synchronized void mark(int readlimit) { bais.mark(readlimit); } @Override public synchronized void reset() throws IOException { bais.reset(); } @Override public boolean markSupported() { return bais.markSupported(); } public static void main(String[] args) throws Exception { List source = new ArrayList(); source.add("foo "); source.add("bar "); source.add("baz"); StringsInputStream> in = new StringsInputStream>(source); int read = in.read(); while (read != -1) { System.out.print((char) read); read = in.read(); } } } 

这基本上是ByteArrayInputStream的适配器。

Answer 4

您也可以这样创建一个Serializable List

 List quarks = Arrays.asList( "up", "down", "strange", "charm", "top", "bottom" ); //serialize the List //note the use of abstract base class references try{ //use buffering OutputStream file = new FileOutputStream( "quarks.ser" ); OutputStream buffer = new BufferedOutputStream( file ); ObjectOutput output = new ObjectOutputStream( buffer ); try{ output.writeObject(quarks); } finally{ output.close(); } } catch(IOException ex){ fLogger.log(Level.SEVERE, "Cannot perform output.", ex); } //deserialize the quarks.ser file //note the use of abstract base class references try{ //use buffering InputStream file = new FileInputStream( "quarks.ser" ); InputStream buffer = new BufferedInputStream( file ); ObjectInput input = new ObjectInputStream ( buffer ); try{ //deserialize the List List recoveredQuarks = (List)input.readObject(); //display its data for(String quark: recoveredQuarks){ System.out.println("Recovered Quark: " + quark); } } finally{ input.close(); } } catch(ClassNotFoundException ex){ fLogger.log(Level.SEVERE, "Cannot perform input. Class not found.", ex); } catch(IOException ex){ fLogger.log(Level.SEVERE, "Cannot perform input.", ex); } 

Answer 5

你可以做类似的事情：

https://commons.apache.org/sandbox/flatfile/xref/org/apache/commons/flatfile/util/ConcatenatedInputStream.html

它只是实现了InputStream的read（）方法，并且有一个连接的InputStream列表。 一旦读取EOF，它就会从下一个InputStream开始读取。 只需将字符串转换为ByteArrayInputStreams即可。