http://cin-ie.iteye.com/blog/859822
關於GZIPInputStream的bug，在jdk的最新版本上竟然還沒解決這個問題。用到gzip的需要注意了：
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4691425
問題描述：
在使用GZIPInputStream對gizp文件進行讀取的時候，使用read方法，方法返回-1，表示該文件讀取真正的結束，但是實際卻並不是這樣。
這些文件在windowsxp用win-rar解壓或者linux上zcat aaa.gz命令進行解壓後，是可以獲得文件的全部內容的。但是在使用GZIPInputStream卻不行。
這個bug是java在讀取gzip文件的時候，還沒有讀取完畢，過早的返回-1，造成有部分文件沒有讀取完畢。
不過好在已經有人解決這個問題了，下面是解決的方法：
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;
}
}
重寫了GZIPInputStream這個類。然後你在使用的時候直接引入MultiMemberGZIPInputStream這個類，並調用即可。
例如：
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new MultiMemberGZIPInputStream(new FileInputStream(gzFile)),
http://blog.csdn.net/hwq1987/article/details/6279130
在解壓gz文件時，如果直接用java.util.zip.GZIPInputStream來處理問題只能解壓很少一部分內容，通過類MultiMemberGZIPInputStream 可以完全解壓一個gz文件。
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
import java.util.zip.GZIPInputStream;
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;
}
}
應用示例：
try {
int nnumber;
FileInputStream fin = new FileInputStream(gzPath);
MultiMemberGZIPInputStream MmGz = new MultiMemberGZIPInputStream(fin);
FileOutputStream fout = new FileOutputStream(topath);
byte[] buf = new byte[1024];
nnumber = MmGz.read(buf, 0, buf.length);
while (nnumber != -1) {
fout.write(buf, 0, nnumber);
nnumber = MmGz.read(buf, 0, buf.length);
}
MmGz.close();
fout.close();
fin.close();
} catch (Exception e) {
e.printStackTrace();
}