http断点续传简单实现（java)

/* 
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**SiteFileFetch.java K_My4>~Il  
*/ 7tyn?t0n  
package NetFox; nVYh1@yLy  
import java.io.*; ]`|bf2*eA  
import java.net.*; )`U T#5  
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public class SiteFileFetch extends Thread { nGP>M#F  
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SiteInfoBean siteInfoBean = null; //文件信息Bean c shZR(b  
long[] nStartPos; //开始位置 l,d8%\  
long[] nEndPos; //结束位置 ZkK +?:9  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Ru sa &#[  
long nFileLength; //文件长度 ZLO_5#<  
boolean bFirst = true; //是否第一次取文件 BgE]xm  
boolean bStop = false; //停止标志 b?Vu9!  
File tmpFile; //文件下载的临时信息 Y@pa+~[{h3  
DataOutputStream output; //输出到文件的输出流 7#<|``]zNf  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 
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public SiteFileFetch(SiteInfoBean bean) throws IOException !Hgq7vZG  
{ 5[;^Em)C  
siteInfoBean = bean; 4
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); !>! l=Z  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Y[pGaiN:  
if(tmpFile.exists ()) sGzd c  
{ K{0mb  
bFirst = false; ))+R*k%  
read_nPos(); i1scoxX3\  
} O,DA{> *m  
else 6bU/IVP  
{ *FqNzly  
nStartPos = new long[bean.getNSplitter()]; yJgnw6>r2  
nEndPos = new long[bean.getNSplitter()]; ^91k@MC  
} m6JIq}CMb  
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} 0tl  
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public void run() =b;v:HC  
{ 8IVKS>  
//获得文件长度 5[I9/4,  
//分割文件 H p1cVs  
//实例FileSplitterFetch ;xs?^N|  
//启动FileSplitterFetch线程 |_2O:
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//等待子线程返回 `!rHH  
try{ c !5OK4+Z  
if(bFirst) z[7U>q[E  
{ [.0R"|$sy+  
nFileLength = getFileSize(); 8rw;Yo<
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if(nFileLength == -1) (3_2h4O  
{ E]+W^VG  
System.err.println("File Length is not known!"); BI}>"',  
} zf^!Zqn[8z  
else if(nFileLength == -2) !iZ*ZPu  
{ G*
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System.err.println("File is not access!"); 9WHkw@<R+  
} &&tQ,5H5  
else  g\n@(T$)  
{ IU3OI:uq  
for(int i=0;i<nStartPos.length;i++) `< VoZ/v  
{ YwKY3kL  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); <6Br]a60RR  
} 8)sqj=  
for(int i=0;i<nEndPos.length-1;i++) ww[STg  
{ ~C[R%%Gu  
nEndPos = nStartPos[i+1]; qA*
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} Kw'A%7^e  
nEndPos[nEndPos.length-1] = nFileLength; RMsr7M4<91  
} TCB<fS~U-  
} KaO8rwzDN  
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//启动子线程 fv)-o&Q#  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; B<_T"n'#b  
for(int i=0;i<nStartPos.length;i++) 9B<y w.  
{ RJ@d_~%U  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), DGp'Xx_8  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 4(o0I~hpB?  
nStartPos,nEndPos,i); X8Gw8^t  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); A4'vJk  
fileSplitterFetch.start(); "bC8/^  
} O@Xl_QNxc!  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), +-xA/nU.c  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); _Z2VS"yH  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $yOfqr  
nEndPos = " + nFileLength); nfl6`)oW  
// fileSplitterFetch[nPos.length-1].start(); Is-Kz}4L  
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//等待子线程结束 #XNe4#  
//int count = 0; T|oz_c\e  
//是否结束while循环 "i9$w\lm  
boolean breakWhile = false; pNE!waR>  
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while(!bStop) .lRO;D  
{ g_.BJ>Uv  
write_nPos(); $JcU0tPq0  
Utility.sleep(500); y?Fh%%uNr  
breakWhile = true; Z\TH=UA  
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for(int i=0;i<nStartPos.length;i++) G+}|gG8  
{ XnV|{X%]U  
if(!fileSplitterFetch.bDownOver) < R0c=BZ>  
{ :*@=px  
breakWhile = false; } fSbH  
break; hX~IZ((Hi8  
} #y2="$V  
} 1\_4# @')  
if(breakWhile) !MQo=k  
break; R1A!ob  
U =T[-(:H  
sL[,J[AN;  
//count++; 4l[f}Z  
//if(count>4) 5
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// siteStop(); 9KD2C>d<  
} 7?B]X%  
b Kv9F@  
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System.err.println("文件下载结束！"); C{+~x@  
} Vk8:;Hj  
catch(Exception e){e.printStackTrace ();} Kkdd}j
 
} 8h-6;x^^  
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//获得文件长度 ;V`~'357%  
public long getFileSize() C %y AMQ  
{ OfY>~d  
int nFileLength = -1; 6-<,1Q'D  
try{ Gz$Ds
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URL url = new URL(siteInfoBean.getSSiteURL()); eH79,!=2  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %xkq
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httpConnection.setRequestProperty("User-Agent","NetFox"); P4ot,Q4  
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int responseCode=httpConnection.getResponseCode(); a&4>xZU #  
if(responseCode>=400) ejD
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{ En-eG37l  
processErrorCode(responseCode); W<k) '|  
return -2; //-2 represent access is error kLADd"C  
} j{S\X'?   
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String sHeader; )7[>/2aGd  
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for(int i=1;;i++) Y!CZ?c)@  
{ )vhHlZ *+  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); w/>k  
//Utility.log(in.readLine()); %e:VeP~  
sHeader=httpConnection.getHeaderFieldKey(i); Pgs4/  
if(sHeader!=null) v!K%\h2A  
{ \O72PC+  
if(sHeader.equals("Content-Length")) }JAg<qy}  
{ N2xgyKy~  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 7@|(z:uw  
break; 6^}GXfJAc  
} e,|"9OK  
} k h#|`E#,  
else d),@&MSN  
break; =i\~][-  
} .\LWV=B  
} [m!$01=  
catch(IOException e){e.printStackTrace ();} qEX59v  
catch(Exception e){e.printStackTrace ();} }=;N3Q" #y  
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Utility.log(nFileLength); <fWho%eOK  
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return nFileLength; J4xt!RW!  
} ${0Xq k  
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//保存下载信息（文件指针位置） jpT!di  
private void write_nPos() [t,grdw  
{ A&)P_B1|  
try{ 2mVH*\D  
output = new DataOutputStream(new FileOutputStream(tmpFile)); i#
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output.writeInt(nStartPos.length); H Viu7kue`  
for(int i=0;i<nStartPos.length;i++) QWxCNt:^?  
{ VqbMFr<k  
// output.writeLong(nPos); 6D_4o&N  
output.writeLong(fileSplitterFetch.nStartPos); <o^mQq&  
output.writeLong(fileSplitterFetch.nEndPos); OA&NWAm4  
} 9O~1o?ni  
output.close(); hFs0qPVY  
} : :e=6i  
catch(IOException e){e.printStackTrace ();} JrYpZ.Nh  
catch(Exception e){e.printStackTrace ();} yEzp+Ky  
}  Js'COO  

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//读取保存的下载信息（文件指针位置） pi3Z)YcT  
private void read_nPos() K\,&wU  
{ c|hKo[r)  
try{ L'z;*N3D  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); /,$6`V  
int nCount = input.readInt(); E!C~*l]wJx  
nStartPos = new long[nCount]; q
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nEndPos = new long[nCount]; H /*^$>0Uo  
for(int i=0;i<nStartPos.length;i++) rS{Rzs^@  
{ f+-w~cN  
nStartPos = input.readLong(); OKxPf]~4E  
nEndPos = input.readLong(); {(7C=)8):  
} wa@X^]D8  
input.close(); `61VP-r  
} M@ ! {m  
catch(IOException e){e.printStackTrace ();} (*^_wq-;  
catch(Exception e){e.printStackTrace ();} / QSK$ZDC  
} 3[-L'!pOX3  
/vwGSuk._  
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private void processErrorCode(int nErrorCode) onHUi]yYu{  
{ u L/*,[}'  
System.err.println("Error Code : " + nErrorCode); f*bs{H'5  
} 33s.p'  
5 S7\m5  
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//停止文件下载 SI8mr`gJ  
public void siteStop() hdfNXZ{A"  
{ D@7\Fg  
bStop = true; yrE|cH'f0  
for(int i=0;i<nStartPos.length;i++) )I$_wB
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fileSplitterFetch.splitterStop(); JG0TbM1(Bt  
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} AIN_.=]"?  
} ~^KemwogPN  
//负责部分文件的抓取 /8Ca8Ju  
**FileSplitterFetch.java `SFI\Y+WDT  
*/ &yp_wW-  
package NetFox; y[.0L!C {  
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import java.io.*; 'FO^VJ;ha  
import java.net.*; O`rAqO0F  
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public class FileSplitterFetch extends Thread { C4#'`8E  
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String sURL; //File URL !sK{:6s  
long nStartPos; //File Snippet Start Position ft?J|AG  
long nEndPos; //File Snippet End Position f.,S-1D]h  
int nThreadID; //Thread's ID !xA;(<K[^  
boolean bDownOver = false; //Downing is over `hY%<L sI  
boolean bStop = false; //Stop identical 3' mQ=tKa  
FileAccessI fileAccessI = null; //File Access interface YDz:;Sp\  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {[NBTT9&  
{ pR; AqDQ  
this.sURL = sURL;
$:{uF#  
this.nStartPos = nStart; J XbG|L  
this.nEndPos = nEnd; )zz"DH  
nThreadID = id; Jd7+~isu~  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ,M5zhp$  
} #9
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public void run() [Xg?sdQCI  
{ g()YP  
while(nStartPos < nEndPos && !bStop) SHIK=&\~-  
{ "b|qyT* Sl  
= 0
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try{ yAW%y  
URL url = new URL(sURL); <x53b/ft  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); [
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httpConnection.setRequestProperty("User-Agent","NetFox");  r@/+  
String sProperty = "bytes="+nStartPos+"-"; |z-A;uL<  
httpConnection.setRequestProperty("RANGE",sProperty); v0apEjT  
Utility.log(sProperty); &3:-(:<U  
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InputStream input = httpConnection.getInputStream(); TMT65X!  
//logResponseHead(httpConnection); /!P,o}l7  
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byte[] b = new byte[1024]; %f*8JUE16  
int nRead; ?qO_t;:0>  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) X8GIRL)lJ  
{ q~T*R<S  
nStartPos += fileAccessI.write(b,0,nRead); !Hr~B.f7  
//if(nThreadID == 1) &
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); HX7"w   
} 1\$xq9  
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 wC}anq>>  
Utility.log("Thread " + nThreadID + " is over!"); qa.nm4"6+  
bDownOver = true; +%UfnbZ  
//nPos = fileAccessI.write (b,0,nRead); /hQTV!\u  
} 0h_9  
catch(Exception e){e.printStackTrace ();} To
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} 9B{,q6  
} g\,pZ]0i  
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9!NL<}]{  
//打印回应的头信息 %7xx"$P:R  
public void logResponseHead(HttpURLConnection con) g~rZ=  
{ !NuiVC]  
for(int i=1;;i++) .-awl1 W  
{ 9i;%(b{  
String header=con.getHeaderFieldKey(i); N>/!e787OU  
if(header!=null) ;xS@-</:  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); NhU~'k  
Utility.log(header+" : "+con.getHeaderField(header)); h.l^f>,/  
else [U5[;BNRD  
break; |k\4\aLj  
} _)"-zbh}{  
} SDwTGQ/0  
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public void splitterStop() bC{}&a  
{ >7V96jL$Y  
bStop = true; ^Vso`(Ss  
} !KKkw
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} K`{P/w  
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/* /Nt#|C>  
**FileAccess.java 4>-'wMW")  
*//文件访问(定位，写) Vzn0;  
package NetFox; Ye% e!  
import java.io.*; ikX"f?Q;S2  
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public class FileAccessI implements Serializable{ BK
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zo6|1xq  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 z$4g9  
RandomAccessFile oSavedFile; YcOPqvQ  
long nPos; t~]n"zgovz  
[% \>FT[  
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public FileAccessI() throws IOException X6)%2TwO  
{ 1j"G~TM  
this("",0); KSDz3qe  
} b+Sq[  
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public FileAccessI(String sName,long nPos) throws IOException h;cl+c|B  
{ DB%}@IW"  
oSavedFile = new RandomAccessFile(sName,"rw"); "jV:L  
this.nPos = nPos; !IF]P#  
oSavedFile.seek(nPos); =1sGT;>  
} fIe';a  
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public synchronized int write(byte[] b,int nStart,int nLen) v=5H,4UMA  
{ HVjN<HIqM  
int n = -1; !ij R  
try{ 0Xo>f"2<f  
oSavedFile.write(b,nStart,nLen); ;E:vsVK  
n = nLen; qW+'#Jh@TV  
} %hDx UZ#0  
catch(IOException e) niC ;WK  
{ uPCzs$R  
e.printStackTrace ();
-[/tS<U  
} m';j#j)w  
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return n; K|L&mL&8  
} vT@*o=I  
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} c"KN;9c,  
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/* pPL)!=o!  
**SiteInfoBean.java HQ /D)D  
*/ 4g4[n7  
package NetFox; _D+pJ{@W  
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public class SiteInfoBean { 9K!kU6Gh  
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private String sSiteURL; //Site's URL t57MKDn  
private String sFilePath; //Saved File's Path s
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private String sFileName; //Saved File's Name :1asY:)vNP  
private int nSplitter; //Count of Splited Downloading File B(|*
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@TJxU  
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public SiteInfoBean() 5 w-Pq&q  
{//nSplitter的缺省值为5 $8>kk  
//default value of nSplitter is 5 hgg8r#4q  
this("","","",5); OQ(w]G0LP  
} +Vv+<M  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) m^!Kthq  
{ 0<i8 ;2KD  
sSiteURL= sURL; i?wEd!=w  
sFilePath = sPath; >Nam@,hm  
sFileName = sName; ZLDO&}  
this.nSplitter = nSpiltter; "DO|B=EejP  
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~=GwNo_  
} P2Jo^WS  
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public String getSSiteURL() p!>5}f6  
{ <-6f}wN  
return sSiteURL; %$Dn);6=  
}
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>:Y"DX-  
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public void setSSiteURL(String value) tm1#Lh0  
{ vh"wXu  
sSiteURL = value; 0Q7|
2{  
} ?K\r-J!Y  
ZH)Jq^^RI  
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public String getSFilePath() p[Zk;AT~  
{ 3AcS$.G  
return sFilePath; Rp+Lu  
} ?;]Xc~  
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public void setSFilePath(String value) VTUSM{TC  
{ uc{s\_  
sFilePath = value; Pm7lP5  
} 3/N~`!zeX  
IM$ d~C  
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public String getSFileName() dQn,0  
{ =AcK9?%5  
return sFileName; }}qY,@eeX  
} |2E:]wT}qg  
.],:pL9d  
*Sg6VGP  
public void setSFileName(String value) ){LU>MW{&  
{ HvR5-?qQ  
sFileName = value; XuoyB{U  
} ;V?3Hwl  
2FN E ;y(  
82)%`$yZw[  
public int getNSplitter() e'yw
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{ g@'2 :'\  
return nSplitter; DH7]TRCMZ)  
} tmd{Gx}c  
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public void setNSplitter(int nCount) `>4"i+NFF8  
{ e?7y$H-  
nSplitter = nCount; :qc?FQ ;  
} pocXQEg$]  
} XU<XK9EA  
2:RFPK  
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/* Aj8zFt]  
**Utility.java }hE!0q~MfM  
*/ /PVx  
package NetFox; U2)?[C1q{  
g"~`\xhx  
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public class Utility { b0sj0w/  
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public Utility() ef7BG(  
{ p//mVH%  
4p7j"d5  
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} DUSQh+C  
? o&goiM  
//线程睡眠 v^J']p  
public static void sleep(int nSecond) ]UkqPtG;  
{ j u&v4]  
try{ <*I*#WI&B  
Thread.sleep(nSecond); A
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} bk0<i*ju7(  
catch(Exception e) r $[{sW  
{ iGSF5S  
e.printStackTrace (); u+y3
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} JqUft=p5  
} iSX HMp4V  
1LaJ hrp?  
//日志 T_qM@/f  
public static void log(String sMsg) ]4/C19Fe!  
{ KRX\<@  
System.err.println(sMsg); !3<b#QAXRG  
} p1[|5r5Day  
!<HF764@`  
/U,(u9bq  
public static void log(int sMsg) uaYI3w@^  
{ F >H\F@Wl  
System.err.println(sMsg); Wv%F^(R7  
} DQ}&J  
} o=RxQk1N  
TV|Z$,6l  
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/* &1Y7Ne
 
**TestMethod.java uJ=d!Kn  
*/ WZn"I&Z  
package NetFox; V*r/0|vd  
}+}Cl T  
Ga+Cb2$  
public class TestMethod { sOVpDtZ]LR  
@#*{* S8  
?^J%S,  
public TestMethod() pI.~j]*:{  
{ ///xx/weblogic60b2_win.exe ^hsr/
|  
try{ G*=&yx."E  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 2kOaKH[(q  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); k{'<J(Hb  
SiteFileFetch fileFetch = new SiteFileFetch(bean); OJ7Uh_;/  
fileFetch.start(); ~c55LlO>  
} ~Y{]yBGoF  
catch(Exception e){e.printStackTrace ();} L
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} +vH#xc\'  
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public static void main(String[] args) -tx%#(?wH  
{ c(29JZ  
new TestMethod(); Zx`/88!x[  
} ~.6% %1?  
} 1;+77<  
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