http断点续传简单实现（java)

/* TL]
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**SiteFileFetch.java >Ban?3{  
*/ ,.q8Xf  
package NetFox; [Q=4P*G}X  
import java.io.*; m"q/,}DR  
import java.net.*; }eI`
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public class SiteFileFetch extends Thread { b<8q 92F  
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SiteInfoBean siteInfoBean = null; //文件信息Bean k5g@myb-  
long[] nStartPos; //开始位置 .h a`)@MsZ  
long[] nEndPos; //结束位置 ;i}i5yv2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ^YqbjL  
long nFileLength; //文件长度 %db3f z  
boolean bFirst = true; //是否第一次取文件 <qr^Nyo4  
boolean bStop = false; //停止标志 Qz# 3p3N?  
File tmpFile; //文件下载的临时信息 s?5d  
DataOutputStream output; //输出到文件的输出流 nc-Qz  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） {dDq*sLf  
public SiteFileFetch(SiteInfoBean bean) throws IOException 22PGWSQ  
{ wJ/~q)  
siteInfoBean = bean; GIK u  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); QT7_x`#J~o  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); \y@ eBW  
if(tmpFile.exists ()) 8KZ$F>T]>  
{ Pb3EnNqYbM  
bFirst = false; Z%KL[R}^w;  
read_nPos(); 4YBf ~Pp  
}
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else j_(?=7Y3g  
{ (e0_RQ  
nStartPos = new long[bean.getNSplitter()]; jm4)gmC  
nEndPos = new long[bean.getNSplitter()]; sK#H4y+<  
} hl*MUD,  
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} "Jf4N  
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public void run() 8u/3?Kc  
{ LPb]mC6
#  
//获得文件长度 #&}%70R)  
//分割文件 >s44  
//实例FileSplitterFetch Io2,% !D  
//启动FileSplitterFetch线程 8TUF w@H%  
//等待子线程返回 )_X;9%L7  
try{ 4(m/D>6:  
if(bFirst) YmZC?x_{M2  
{ 1V#0\1sj  
nFileLength = getFileSize(); 8rla0d@  
if(nFileLength == -1) FYxUOO  
{ b8eDD+ulk  
System.err.println("File Length is not known!"); gQu\[e%mVo  
} eB)UXOu1  
else if(nFileLength == -2) o`oRG)QC  
{ 3D{82*&  
System.err.println("File is not access!"); [kVpzpGr  
} [5x+aW%ql  
else P0a>+^:%  
{ [^h/(a`  
for(int i=0;i<nStartPos.length;i++) e6Wl7&@6  
{ ?SHc}iaU#  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); E=$7ieW  
} .%|OGl ?  
for(int i=0;i<nEndPos.length-1;i++) H't`Q&]a  
{ 7Ntjx(b$"h  
nEndPos = nStartPos[i+1];  s$K@X `  
} z?8zFP  
nEndPos[nEndPos.length-1] = nFileLength; J,CJPUf&  
} P9 W<gIO  
} S~]8K8"sT  
n P0Ziu'{  
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//启动子线程 a.5zdoH_  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; b>GqNf!  
for(int i=0;i<nStartPos.length;i++) >^M!@=/?J  
{ mABwM$_  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ?FkQe~FN{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), N:m@D][/sW  
nStartPos,nEndPos,i); <|mE9u  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ,e}mR>i=e  
fileSplitterFetch.start(); *?EjYI  
} fx8y`8}_  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ZE5-i@1  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 2<`gs(oxXe  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", |6\FI?  
nEndPos = " + nFileLength); V
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// fileSplitterFetch[nPos.length-1].start(); -MVNXAKnZ  
; |
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'XC&BW
J  
//等待子线程结束 nPQZI6>  
//int count = 0; r*~n`  
//是否结束while循环 '[7C~r{%  
boolean breakWhile = false; ,U} 5  
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while(!bStop) (h'$3~  
{ [wXwKr  
write_nPos(); /6Jy'"+'0  
Utility.sleep(500); 3G:NZ)p  
breakWhile = true; ,"v)vTt  
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for(int i=0;i<nStartPos.length;i++) 6KBzlj0T+  
{ N,'[:{GOY  
if(!fileSplitterFetch.bDownOver) r7]?g~zb  
{ mjkw&2  
breakWhile = false; 3Vb=6-|  
break; LOyCx/n  
} r1^m#!=B  
} 5bGjO&$l  
if(breakWhile) J?|K
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break; yhJA;&}>  
*Bb|N--jI  
q.u[g0h;  
//count++; YU ]G5\UU  
//if(count>4) UIm[DYMS  
// siteStop(); (}/.4xE  
} R-2FNl  
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System.err.println("文件下载结束！"); i_jax)m%  
} o[
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catch(Exception e){e.printStackTrace ();} Bsih<`KF^  
} /eU1(oo&`5  
*'AS^2'  
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//获得文件长度 jx5
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public long getFileSize() lN][xnP  
{ +*r**(-Dm  
int nFileLength = -1; JYVxdvq1  
try{ {{4p{  
URL url = new URL(siteInfoBean.getSSiteURL()); 1b %T_a  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); {YO%JTQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); p'uqh e X  
t^bdi}[  
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int responseCode=httpConnection.getResponseCode(); GWA!Ab'<U  
if(responseCode>=400) mv9E{m  
{ 6Mf3)o2  
processErrorCode(responseCode); fa*H cz  
return -2; //-2 represent access is error ,:dEEL+>c  
} 9 z8<[>  
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String sHeader; Vm,f3~  
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for(int i=1;;i++) t}c}@i_c  
{ ;ow~vO,x  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 7S~9E2N  
//Utility.log(in.readLine()); Fv7%TK{oe  
sHeader=httpConnection.getHeaderFieldKey(i); 44fq1<.K  
if(sHeader!=null) _:fO)gs|1  
{ D-b2E6o6  
if(sHeader.equals("Content-Length")) GJ^]ER-K  
{ hB GGs  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); *n|0\V<  
break; tci%=3,)  
} HC;I0&v>  
} kT }'"  
else 5w [=  
break; ]ZryY EB  
} &Lt$a_y>  
} Rm\'];  
catch(IOException e){e.printStackTrace ();} 5?~[|iPv  
catch(Exception e){e.printStackTrace ();} x[O#(^q  
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Utility.log(nFileLength); R{OE{8;  
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return nFileLength; BtNW5'^  
} v<J;S9u=  

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//保存下载信息（文件指针位置） t+4Y3*WeGF  
private void write_nPos() g0:4zeL  
{ f;tyoN0wHx  
try{ mTuB
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output = new DataOutputStream(new FileOutputStream(tmpFile)); c]>&6-;rf  
output.writeInt(nStartPos.length); &6^W%r  
for(int i=0;i<nStartPos.length;i++) :2UC{_  
{ b-(UsY:  
// output.writeLong(nPos); :kiO  
output.writeLong(fileSplitterFetch.nStartPos); M6hvi(!X2  
output.writeLong(fileSplitterFetch.nEndPos); vb"dX0)<  
} /4B4IT  
output.close(); N7I71q|  
} 1={Tcq\]  
catch(IOException e){e.printStackTrace ();} 4(0t GF  
catch(Exception e){e.printStackTrace ();} {EoyMJgz  
} noUZ9M|hz  
,I&0#+}n  
548[!p4  
//读取保存的下载信息（文件指针位置） 3P^gP32  
private void read_nPos() )x:j5{>(  
{ tj^:SW.0  
try{ S_ -QvG2  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); };|PFWs  
int nCount = input.readInt(); 5 *pN<S  
nStartPos = new long[nCount]; ks#Z~6+3  
nEndPos = new long[nCount]; /jn3'q_,  
for(int i=0;i<nStartPos.length;i++) 4@mXtA  
{
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nStartPos = input.readLong(); i(f;'fb*  
nEndPos = input.readLong(); 6[h$r/GXh"  
} f~"V  
input.close(); FvNSu"O~K1  
} v.LUK  
catch(IOException e){e.printStackTrace ();} wAOVH].  
catch(Exception e){e.printStackTrace ();} nM.?Q}yO~  
} B%g:
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private void processErrorCode(int nErrorCode) Gxa.<E^k  
{ BfE-s<  
System.err.println("Error Code : " + nErrorCode); v{{2<,l  
} ,8o*!(uO2  
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//停止文件下载 ;1g-z]  
public void siteStop() g&F<Uv#mZ  
{ A{Htpm~  
bStop = true; )>M@hIV5>  
for(int i=0;i<nStartPos.length;i++) '-]BSU  
fileSplitterFetch.splitterStop(); qddT9U|8~  
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} O9=H [b  
} p,u<gJUL  
//负责部分文件的抓取 07"Oj9NlA  
**FileSplitterFetch.java U>-#('  
*/ ODvpMt:+  
package NetFox; zcWxyLifl0  
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import java.io.*; lvJ{=~u  
import java.net.*; I+d(r"N1  
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public class FileSplitterFetch extends Thread { s
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String sURL; //File URL VrE5^\k<a  
long nStartPos; //File Snippet Start Position 1LIV/l^}f  
long nEndPos; //File Snippet End Position ftH%, /,  
int nThreadID; //Thread's ID TIhzMW\/K  
boolean bDownOver = false; //Downing is over _%Ld Ez  
boolean bStop = false; //Stop identical J9=0?^v-:B  
FileAccessI fileAccessI = null; //File Access interface JIKxY$GS  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 5"~^;O  
{ HgATH  
this.sURL = sURL; ]bE?n.NwZ  
this.nStartPos = nStart; !gew;Jz  
this.nEndPos = nEnd; N&h!14]{Z  
nThreadID = id; 6Oba}`)q9  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 8 (h  
} ^
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public void run() j"u)
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{ M>gZVB,eP>  
while(nStartPos < nEndPos && !bStop) T<?BIQz(}  
{ +*{5ORq=  
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try{ K
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URL url = new URL(sURL); G5f57F  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _1c_TMh}9  
httpConnection.setRequestProperty("User-Agent","NetFox"); V"jnrNs3  
String sProperty = "bytes="+nStartPos+"-"; s'Q^1oQM2h  
httpConnection.setRequestProperty("RANGE",sProperty); l'%R^  
Utility.log(sProperty); ^|;4/=bbs  
'0$[Ujc  
}F`2$Q+CW  
InputStream input = httpConnection.getInputStream(); W*`6ero  
//logResponseHead(httpConnection); pDq_nx9  
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byte[] b = new byte[1024]; "]V|bz o0a  
int nRead; * .VZ(wX  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 1+}Ud.v3VW  
{ V>92/w.fe  
nStartPos += fileAccessI.write(b,0,nRead); <1.mm_pw  
//if(nThreadID == 1) -%) !XB  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ;O|63  
} 2B dr#qr  
xF|*N<9(</  
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Utility.log("Thread " + nThreadID + " is over!"); aBi:S3 qk  
bDownOver = true; J}\]<aC
 
//nPos = fileAccessI.write (b,0,nRead); 4F6o  
} /-4B)mL  
catch(Exception e){e.printStackTrace ();} %\&
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} *v/*_6
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} : X|7l?{xW  
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//打印回应的头信息 JHH&@Cn  
public void logResponseHead(HttpURLConnection con) Vp{2Z9]}  
{ }_;!E@  
for(int i=1;;i++) &ru0i@?)  
{ @0'|Uygn  
String header=con.getHeaderFieldKey(i); _u2  
if(header!=null) JhIK$Ti  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); a`Zf_;$@  
Utility.log(header+" : "+con.getHeaderField(header)); }8#Czo jt  
else o|q#A3%?  
break; 7b2<, .E  
} In M'zAhb  
} AI;=k  
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public void splitterStop() #K w\r50  
{ 9(j!#`O7&  
bStop = true; ??V["o T  
} :%MWbnVSC,  
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} \9QOrjiw  
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/* a"aV&t  
**FileAccess.java q8>Q,F`BA  
*//文件访问(定位，写) A,qG*l
v  
package NetFox; Q~_x%KN/`  
import java.io.*; ;D:T ^4  
'DQyB`V2y  
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public class FileAccessI implements Serializable{ S &u94hlC  
90}B*3x  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 (Lnh> '2  
RandomAccessFile oSavedFile; j83 V$ Le  
long nPos; CI{x/ e^(  
!&[4T#c  
9<S-b |!@  
public FileAccessI() throws IOException e_TDO   
{ 2wQ CQ"  
this("",0); ;zDc0qpw  
} mGvP9E"&  
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public FileAccessI(String sName,long nPos) throws IOException )3sb2 #  
{ mN02T@R-  
oSavedFile = new RandomAccessFile(sName,"rw"); za7wNe(s  
this.nPos = nPos; _wCSL.  
oSavedFile.seek(nPos); W6Pg:Il7  
} C.<4D1}P  
bAp`lmFI  
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public synchronized int write(byte[] b,int nStart,int nLen) g\'sGt3O  
{ 2|BE{91  
int n = -1; F1>,^qyG6  
try{ ^ a:F*<D  
oSavedFile.write(b,nStart,nLen); kx[8#+P  
n = nLen; s8Oz^5p(  
} *Y Ox`z!R  
catch(IOException e) A_%w(7o"  
{ 2+PIZ6=hN  
e.printStackTrace (); 0P(}e[~Z  
} M_K&x-H0  
)f Rh^6  
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return n; zlE kP @)  
} d@hJ=-4  
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} K-ebAaiC  
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/* h*LIS@&9C5  
**SiteInfoBean.java }qTvUs  
*/ /hQ!dU.+  
package NetFox; X}$S|1CjO  
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public class SiteInfoBean { fJuJ#MX{:  
(C&f~U  
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private String sSiteURL; //Site's URL &3<]FK  
private String sFilePath; //Saved File's Path &!ZpBR(  
private String sFileName; //Saved File's Name b11C3TyQT  
private int nSplitter; //Count of Splited Downloading File *RPI$0
 
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public SiteInfoBean() e 6*=Si}V  
{//nSplitter的缺省值为5 S:gP\Atf>  
//default value of nSplitter is 5 # V+e  
this("","","",5); $3>|RlxYA  
} ~&kV  
TUG3#PSnm*  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) o&=m]hKpQl  
{ *h UrE  
sSiteURL= sURL; ZD3S|1zSQ  
sFilePath = sPath; f4q-wX_1  
sFileName = sName; Jy9&=Qh   
this.nSplitter = nSpiltter; 3I]5DW %-  
]#`bYh^y  
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} ZYG"nmNd  
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public String getSSiteURL() Z\x6  
{ 3jeR;N]x  
return sSiteURL; 5@Sb[za  
}
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V;$lgTs|'  
public void setSSiteURL(String value) ?S"xR0 *  
{ &3rh{"^9  
sSiteURL = value; ?pFHpz  
} k:fRk<C  
]BA8[2=m  
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public String getSFilePath() @Z)&
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{ T"O!  
return sFilePath; '?\Hm'8  
} xed$z  
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public void setSFilePath(String value) fYwumx`J  
{ pcE.  
sFilePath = value; gbvBgOp  
} t^q/'9Ai&J  
il:""x7^y  
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public String getSFileName() l! GPOmf9`  
{ aD.A +es  
return sFileName; D`u{U]  
} Ou/{PK}  
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public void setSFileName(String value) 7JbN WN  
{ #VLTx!5o  
sFileName = value; 'SC`->F4D  
} #]9yzyb_y  
.NjOaK)\  
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public int getNSplitter() \eN}V  
{ IlH*s/  
return nSplitter; .69{GM?  
} b(wiJ&t  
[K^RC;}nV^  
\hg12],#:@  
public void setNSplitter(int nCount) !aLL|}S  
{ Ax&+UxQ0|  
nSplitter = nCount; ~#wq sm  
} $N~8^6  
} )F:hv[iv  
TtHqdKL  
K1Uur>Pk%  
/* 1g *4e  
**Utility.java %GJ,&b|
 
*/
?]:3`;h3  
package NetFox; By" =]|Q  
}_K7}] 1  
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public class Utility { ?>2k>~xlQ  
|@Bl?Bs+  
(%tKGeb
  
public Utility() vFQ'sd]C  
{ b?y3m +V`  
+g(QF
  
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} E#J+.&2  
-|g~--@Q  
//线程睡眠 0C7x1:  
public static void sleep(int nSecond) 4jvgyi9  
{ 8dP^zjPj  
try{ yKi* 8N"e<  
Thread.sleep(nSecond); ^dQ#\uy  
} $P>ci4]t  
catch(Exception e) ENygD  
{ 66v6do7  
e.printStackTrace (); /mmCqP  
} |[8&5[);  
} "Q^Ck7  
'(;`t1V8k  
//日志 h60*=+vdJ  
public static void log(String sMsg) S_WYU&8  
{ Mc9%s$MT  
System.err.println(sMsg); c{zQX0  
} >a[)F  
q'[5h>Pa  
4&}LYSZl  
public static void log(int sMsg) G;MmD?VJ g  
{ H{yeN 5   
System.err.println(sMsg); Yz4Q!tL  
} >IsRd  
} |.X?IJ`  
1Jt5|'tl  
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/* Tmqtj  
**TestMethod.java `|[Q]+Mx  
*/ u`3J2,.  
package NetFox; 4Z,MqG>  
3 cu`U`  
>k5nU^|B1  
public class TestMethod { Ab/gY$l  
}/Pz1,/  
]:d`=V\&N  
public TestMethod() }[k~JXt  
{ ///xx/weblogic60b2_win.exe voEg[Gg4%I  
try{ h#a,<B|  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); :>]=YE  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); vdV@G`)HPr  
SiteFileFetch fileFetch = new SiteFileFetch(bean); #3leMZ6  
fileFetch.start(); Z+x,Awq  
} o[X'We;  
catch(Exception e){e.printStackTrace ();} !ffdeWHR  
{%*,KB>b  
?Mtd3F^o?  
} OW;]=k/(  
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0"#'Z>"  
public static void main(String[] args) NJRk##Z  
{ _SY4Qs`d  
new TestMethod(); 1:(qoA:  
} k?ZtRhPu3X  
} =Q>'?w>  
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