我在开发阶段,在那里我有两个模块,从一个我得到输出作为一个OutputStream和第二个,它只接受InputStream。你知道如何将OutputStream转换为InputStream(反之亦然,我的意思是真的这样),我将能够连接这两个部分吗?
谢谢
我在开发阶段,在那里我有两个模块,从一个我得到输出作为一个OutputStream和第二个,它只接受InputStream。你知道如何将OutputStream转换为InputStream(反之亦然,我的意思是真的这样),我将能够连接这两个部分吗?
谢谢
当前回答
库io-extras可能很有用。例如,如果你想使用GZIPOutputStream gzip一个InputStream,并且你希望它同步发生(使用默认的缓冲区大小8192):
InputStream is = ...
InputStream gz = IOUtil.pipe(is, o -> new GZIPOutputStream(o));
请注意,该库具有100%的单元测试覆盖率(当然,这是值得的!),并且位于Maven Central上。Maven依赖项是:
<dependency>
<groupId>com.github.davidmoten</groupId>
<artifactId>io-extras</artifactId>
<version>0.1</version>
</dependency>
一定要查看更新的版本。
其他回答
easystream开源库直接支持将OutputStream转换为InputStream: http://io-tools.sourceforge.net/easystream/tutorial/tutorial.html
// create conversion
final OutputStreamToInputStream<Void> out = new OutputStreamToInputStream<Void>() {
@Override
protected Void doRead(final InputStream in) throws Exception {
LibraryClass2.processDataFromInputStream(in);
return null;
}
};
try {
LibraryClass1.writeDataToTheOutputStream(out);
} finally {
// don't miss the close (or a thread would not terminate correctly).
out.close();
}
他们还列出了其他选项:http://io-tools.sourceforge.net/easystream/outputstream_to_inputstream/implementations.html
Write the data the data into a memory buffer (ByteArrayOutputStream) get the byteArray and read it again with a ByteArrayInputStream. This is the best approach if you're sure your data fits into memory. Copy your data to a temporary file and read it back. Use pipes: this is the best approach both for memory usage and speed (you can take full advantage of the multi-core processors) and also the standard solution offered by Sun. Use InputStreamFromOutputStream and OutputStreamToInputStream from the easystream library.
库io-extras可能很有用。例如,如果你想使用GZIPOutputStream gzip一个InputStream,并且你希望它同步发生(使用默认的缓冲区大小8192):
InputStream is = ...
InputStream gz = IOUtil.pipe(is, o -> new GZIPOutputStream(o));
请注意,该库具有100%的单元测试覆盖率(当然,这是值得的!),并且位于Maven Central上。Maven依赖项是:
<dependency>
<groupId>com.github.davidmoten</groupId>
<artifactId>io-extras</artifactId>
<version>0.1</version>
</dependency>
一定要查看更新的版本。
你需要一个中间类来缓冲。每次调用InputStream.read(byte[]…)时,缓冲类将用从OutputStream.write(byte[]…)传入的下一个块填充传入的字节数组。由于块的大小可能不相同,适配器类需要存储一定数量的块,直到它有足够的容量填满读缓冲区和/或能够存储任何缓冲区溢出。
这篇文章很好地分解了解决这个问题的几种不同方法:
http://blog.ostermiller.org/convert-java-outputstream-inputstream
我遇到了同样的问题,将ByteArrayOutputStream转换为ByteArrayInputStream,并通过使用ByteArrayOutputStream的派生类来解决它,它能够返回一个ByteArrayInputStream,该ByteArrayInputStream是由ByteArrayOutputStream的内部缓冲区初始化的。这种方式不会使用额外的内存,而且“转换”非常快:
package info.whitebyte.utils;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
/**
* This class extends the ByteArrayOutputStream by
* providing a method that returns a new ByteArrayInputStream
* which uses the internal byte array buffer. This buffer
* is not copied, so no additional memory is used. After
* creating the ByteArrayInputStream the instance of the
* ByteArrayInOutStream can not be used anymore.
* <p>
* The ByteArrayInputStream can be retrieved using <code>getInputStream()</code>.
* @author Nick Russler
*/
public class ByteArrayInOutStream extends ByteArrayOutputStream {
/**
* Creates a new ByteArrayInOutStream. The buffer capacity is
* initially 32 bytes, though its size increases if necessary.
*/
public ByteArrayInOutStream() {
super();
}
/**
* Creates a new ByteArrayInOutStream, with a buffer capacity of
* the specified size, in bytes.
*
* @param size the initial size.
* @exception IllegalArgumentException if size is negative.
*/
public ByteArrayInOutStream(int size) {
super(size);
}
/**
* Creates a new ByteArrayInputStream that uses the internal byte array buffer
* of this ByteArrayInOutStream instance as its buffer array. The initial value
* of pos is set to zero and the initial value of count is the number of bytes
* that can be read from the byte array. The buffer array is not copied. This
* instance of ByteArrayInOutStream can not be used anymore after calling this
* method.
* @return the ByteArrayInputStream instance
*/
public ByteArrayInputStream getInputStream() {
// create new ByteArrayInputStream that respects the current count
ByteArrayInputStream in = new ByteArrayInputStream(this.buf, 0, this.count);
// set the buffer of the ByteArrayOutputStream
// to null so it can't be altered anymore
this.buf = null;
return in;
}
}
我把这些东西放在github: https://github.com/nickrussler/ByteArrayInOutStream上
老帖子,但可能会帮助别人,使用这种方式:
OutputStream out = new ByteArrayOutputStream();
...
out.write();
...
ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(out.toString().getBytes()));