关于GZIPInputStream的bug,在jdk的最新版本上竟然还没解决这个问题。用到gzip的需要注意了:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4691425
问题描述:
在使用GZIPInputStream对gizp文件进行读取的时候,使用read方法,方法返回-1,表示该文件读取真正的结束,但是实际却并不是这样。
这些文件在windowsxp用win-rar解压或者linux上zcat aaa.gz命令进行解压后,是可以获得文件的全部内容的。但是在使用GZIPInputStream却不行。
这个bug是java在读取gzip文件的时候,还没有读取完毕,过早的返回-1,造成有部分文件没有读取完毕。
不过好在已经有人解决这个问题了,下面是解决的方法:
package x.y.z;
import java.io.InputStream;
import java.io.PushbackInputStream;
import java.io.IOException;
public
class MultiMemberGZIPInputStream extends GZIPInputStream {
public MultiMemberGZIPInputStream(InputStream in, int size) throws IOException
{
// Wrap the stream in a PushbackInputStream…
super(new PushbackInputStream(in, size), size);
this.size=size;
}
public MultiMemberGZIPInputStream(InputStream in) throws IOException
{
// Wrap the stream in a PushbackInputStream…
super(new PushbackInputStream(in, 1024));
this.size=-1;
}
private MultiMemberGZIPInputStream(MultiMemberGZIPInputStream parent) throws IOException
{
super(parent.in);
this.size=-1;
this.parent=parent.parent==null ? parent : parent.parent;
this.parent.child=this;
}
private MultiMemberGZIPInputStream(MultiMemberGZIPInputStream parent, int size) throws IOException
{
super(parent.in, size);
this.size=size;
this.parent=parent.parent==null ? parent : parent.parent;
this.parent.child=this;
}
private MultiMemberGZIPInputStream parent;
private MultiMemberGZIPInputStream child;
private int size;
private boolean eos;
public int read(byte[] inputBuffer, int inputBufferOffset, int inputBufferLen) throws IOException {
if (eos) { return -1;}
if (this.child!=null)
return this.child.read(inputBuffer, inputBufferOffset, inputBufferLen);
int charsRead=super.read(inputBuffer, inputBufferOffset, inputBufferLen);
if (charsRead==-1)
{
// Push any remaining buffered data back onto the stream
// If the stream is then not empty, use it to construct
// a new instance of this class and delegate this and any
// future calls to it…
int n = inf.getRemaining() – 8;
if (n > 0)
{
// More than 8 bytes remaining in deflater
// First 8 are gzip trailer. Add the rest to
// any un-read data…
((PushbackInputStream)this.in).unread(buf, len-n, n);
}
else
{
// Nothing in the buffer. We need to know whether or not
// there is unread data available in the underlying stream
// since the base class will not handle an empty file.
// Read a byte to see if there is data and if so,
// push it back onto the stream…
byte[] b=new byte[1];
int ret=in.read(b,0,1);
if (ret==-1)
{
eos=true;
return -1;
}
else
((PushbackInputStream)this.in).unread(b, 0, 1);
}
MultiMemberGZIPInputStream child;
if (this.size==-1)
child=new MultiMemberGZIPInputStream(this);
else
child=new MultiMemberGZIPInputStream(this, this.size);
return child.read(inputBuffer, inputBufferOffset, inputBufferLen);
}
else
return charsRead;
}
}
重写了GZIPInputStream这个类。然后你在使用的时候直接引入MultiMemberGZIPInputStream这个类,并调用即可。
例如:
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new MultiMemberGZIPInputStream(new FileInputStream(gzFile)),
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