http断点续传简单实现（java)

/* ^%X
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**SiteFileFetch.java Q fyERa\rb  
*/ ;
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package NetFox; ^oB1 &G  
import java.io.*; qf=[*ZY  
import java.net.*; fG$.DvJuK  
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public class SiteFileFetch extends Thread { %+!9  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 3<lhoD  
long[] nStartPos; //开始位置 nJ#@W b@  
long[] nEndPos; //结束位置 U(]5U^  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 2y7q x1$C  
long nFileLength; //文件长度 M)pi)$&c  
boolean bFirst = true; //是否第一次取文件 p33GKg0i+(  
boolean bStop = false; //停止标志 o4f9EJY  
File tmpFile; //文件下载的临时信息 Odtck9
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DataOutputStream output; //输出到文件的输出流 X$&Sw3c  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） *3 8Y;{ 4  
public SiteFileFetch(SiteInfoBean bean) throws IOException 2^ZPO4|  
{ I^Jp )k*z  
siteInfoBean = bean; {=4:Tgw  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +<WT$ddK=5  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ~wg^>!E  
if(tmpFile.exists ()) =<h=">}5'  
{ ;Hr@0f  
bFirst = false; 1WN93SQ=  
read_nPos(); a&VJYAB  
} I3$vw7}5Y  
else wSyu^KDz  
{ RX\O'Zwlj  
nStartPos = new long[bean.getNSplitter()]; W1`ZS*12D  
nEndPos = new long[bean.getNSplitter()]; q;PzB4#  
} 2^M+s\p  
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} #7T={mh  
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public void run() 7uNI  
{ bK1`a{  
//获得文件长度 ,T
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//分割文件 aKtTx~$@  
//实例FileSplitterFetch M':.b+xN  
//启动FileSplitterFetch线程 <ijmkNVS  
//等待子线程返回 ?R:Hj=.  
try{ rO%+)M$A  
if(bFirst) *~^^A9C8  
{ @il}0  
nFileLength = getFileSize(); P`"DepeD  
if(nFileLength == -1) v[3sg2.  
{
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System.err.println("File Length is not known!"); x,_Ucc.  
} e'VXyf  
else if(nFileLength == -2) OR8o%AxL7  
{ /n:fxdhe  
System.err.println("File is not access!"); S]g)^f'a65  
} )ixE  
else CnYX\^Ow  
{ ,SwaDWNO  
for(int i=0;i<nStartPos.length;i++) e'&{KD,-T  
{ QLG,r^  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); !:{_<C"D  
} 59 Y=VS
 
for(int i=0;i<nEndPos.length-1;i++) `VN<6o(  
{ \ y",Qq?  
nEndPos = nStartPos[i+1]; iL1so+di  
} yqI|BF`  
nEndPos[nEndPos.length-1] = nFileLength; `BD`pa7.%  
} \s'6)_  
} Y%@'a~  
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//启动子线程 M-|2W~YU  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; B=|sLs`I  
for(int i=0;i<nStartPos.length;i++) IPR396J+-  
{ heA\6W:u&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), RA/yvr  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 7yl'!uz)9  
nStartPos,nEndPos,i); 2
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); +Ti@M1A&  
fileSplitterFetch.start(); 'L/TaP/3  
} .`XA6e(8KR  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), iX p8u**  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); l !v#6#iq  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", E!M+37/  
nEndPos = " + nFileLength); +%v4Ci"%y  
// fileSplitterFetch[nPos.length-1].start(); Cj9Tj'0@I+  
\gpKQt0  
rC16?RovQ@  
//等待子线程结束 17d$gZ1O:  
//int count = 0; t:7jlD!d  
//是否结束while循环 b87o6"j  
boolean breakWhile = false; CuNHDYQ&3  
M(f'qFY=K  
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while(!bStop) ~Y[1Me  
{ fHi+PEbR  
write_nPos(); qFk(UazN  
Utility.sleep(500);
04t_  
breakWhile = true; Nfh(2gK+  
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for(int i=0;i<nStartPos.length;i++) PYe>`X?  
{ oL;/Qan  
if(!fileSplitterFetch.bDownOver) N}=-+E|  
{ ;21JM2JI8  
breakWhile = false; {Xj%JE[V  
break; CiSG=obw  
} I j /J  
} P.Bk-#}$  
if(breakWhile) ->(B:Cz  
break; 79DC]48M  
j>iM(8`t1  
hCgNS1%4  
//count++; &AVi4zV  
//if(count>4) p:jrqjLp  
// siteStop(); 4]GyuY  
} m[f\I^\%8  
5cU8GgN`  
53QP~[F8R]  
System.err.println("文件下载结束！"); ilP&ctn6+c  
} J98K:SAR  
catch(Exception e){e.printStackTrace ();} J
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} z$NLFJvy_-  
u(R`}C?P'  
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//获得文件长度 Z6p>R;9n  
public long getFileSize() R/W&~t  
{ H;6V  
int nFileLength = -1; ` T!O )5  
try{ oaHBz_pg  
URL url = new URL(siteInfoBean.getSSiteURL()); -vyC,A  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); -Da_#_F  
httpConnection.setRequestProperty("User-Agent","NetFox"); >&R|t_ypw  
]:;gk&P  
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int responseCode=httpConnection.getResponseCode(); Z&%61jGK  
if(responseCode>=400) ?6Gq &  
{ w%ForDB>P  
processErrorCode(responseCode); O
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return -2; //-2 represent access is error
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} l},%g%}iMU  
.
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String sHeader; zri<'W  
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for(int i=1;;i++) W
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{ Y9WH%  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ,O2F}5|;  
//Utility.log(in.readLine()); +#W5Qb}VR  
sHeader=httpConnection.getHeaderFieldKey(i); Pw")|85  
if(sHeader!=null) r~sGot+sQA  
{ R:E`  
if(sHeader.equals("Content-Length")) tFGLqR%/  
{ U+K_eEI0_I  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); h3:k$`_  
break; =X`/.:%|[  
} u
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} 7 MfpZgC  
else 0<Y)yNsV  
break; 6ugBbP +^  
} n8?gZ` W  
} qRU8uu  
catch(IOException e){e.printStackTrace ();} yCz
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catch(Exception e){e.printStackTrace ();} mBNa;6w?{*  
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Utility.log(nFileLength); {PfE7KH  
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return nFileLength; a`T{5*@  
} p~r +2(J
 
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//保存下载信息（文件指针位置） k -SUp8}g  
private void write_nPos() `0sa94H1[  
{ 4Ld0AApncy  
try{
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output = new DataOutputStream(new FileOutputStream(tmpFile)); jtZ@`io  
output.writeInt(nStartPos.length); q* m%Fv  
for(int i=0;i<nStartPos.length;i++) T-27E$0  
{ W nVX)o  
// output.writeLong(nPos); r`" ?K]rI  
output.writeLong(fileSplitterFetch.nStartPos); [E=
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output.writeLong(fileSplitterFetch.nEndPos); r:u5+A  
} 7Npz {C{I  
output.close(); 1{DHlyA6g  
} 5H<rI?  
catch(IOException e){e.printStackTrace ();} 7)[4|I  
catch(Exception e){e.printStackTrace ();} ;'nu9FU*O  
} -tDmzuD6  
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//读取保存的下载信息（文件指针位置） .>&kAf.  
private void read_nPos() |vzGFfRI  
{ ,cpPXcz?,  
try{ p#3P`I>ZrT  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 8TuOf(qE  
int nCount = input.readInt(); iA=
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nStartPos = new long[nCount]; #A?U_32z/2  
nEndPos = new long[nCount]; Y,?rykRj  
for(int i=0;i<nStartPos.length;i++) 4j/8Otn  
{ VN*^pAzlF  
nStartPos = input.readLong(); G:f]z;Xdp  
nEndPos = input.readLong(); W<kJ%42^j  
} W|~Ehg  
input.close(); " >;},$  
} rlW
  
catch(IOException e){e.printStackTrace ();} t+ Fm?  
catch(Exception e){e.printStackTrace ();} (]rtBeT  
} U2!9Tl9".  

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private void processErrorCode(int nErrorCode) h@l5MH=|%  
{ J,k9?nkY /  
System.err.println("Error Code : " + nErrorCode); jiz"`,-},O  
} y~;Kf0~  
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oT.g@kf=H  
//停止文件下载 )mJl-u[0+  
public void siteStop() 9V("K  
{ ~-JkuRJ\  
bStop = true; 'Aai.PE:  
for(int i=0;i<nStartPos.length;i++) :jgwp~l  
fileSplitterFetch.splitterStop(); @ScH"I];uA  
<
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} DTPYCG&%  
} ho;Km  
//负责部分文件的抓取 z`5d,M  
**FileSplitterFetch.java KE6[u*\  
*/ r( :"BQ  
package NetFox; }5FdX3YR  
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import java.io.*; 80LKxA;5N  
import java.net.*; Fz~-m#Ts  
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public class FileSplitterFetch extends Thread { -(ABQgSO]  
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String sURL; //File URL d7qHUx'=z  
long nStartPos; //File Snippet Start Position la[xbv   
long nEndPos; //File Snippet End Position 1|Us"GQ(n  
int nThreadID; //Thread's ID MkF:1-=L  
boolean bDownOver = false; //Downing is over Z>{3t/`  
boolean bStop = false; //Stop identical ,?P@ :S<8  
FileAccessI fileAccessI = null; //File Access interface 1nye.i~  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException swntz  
{ Wf +j/RxTi  
this.sURL = sURL;
Nl"< $/  
this.nStartPos = nStart; %tT&/F  
this.nEndPos = nEnd; PTXy:>]M  
nThreadID = id; +'Ec)7m  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 TXWi5f[  
} 9#IKb:9k  
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public void run() h/j+b.|  
{ y2bL!Y<s9  
while(nStartPos < nEndPos && !bStop) ?kqo~twJ  
{ *tC]Z&5  
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|W];8  
try{ SQ9s  
URL url = new URL(sURL); '5\7>2fI  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); -{dsl|Dl  
httpConnection.setRequestProperty("User-Agent","NetFox"); \BOZhXfl'  
String sProperty = "bytes="+nStartPos+"-";
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httpConnection.setRequestProperty("RANGE",sProperty); 7{e0^V,\k  
Utility.log(sProperty); dlsVE~_G  
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InputStream input = httpConnection.getInputStream(); ;cgc\xm>  
//logResponseHead(httpConnection); vtM!?#  
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byte[] b = new byte[1024]; Z[[ou?c  
int nRead; }u8o*P|,  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) c%9wI*l  
{ tkx1iBW=  
nStartPos += fileAccessI.write(b,0,nRead); ,iY/\ U''  
//if(nThreadID == 1) ?&W1lYY  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); L8("1_  
} u4*7n-(  
=X6WK7^0  
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Utility.log("Thread " + nThreadID + " is over!"); ]y= ff6Q  
bDownOver = true; =LEKFXqM  
//nPos = fileAccessI.write (b,0,nRead); 28J ;9  
} l ps 6lnh  
catch(Exception e){e.printStackTrace ();} ~?TG
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} *$mDu,'8  
} 3
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//打印回应的头信息 p_T>"v  
public void logResponseHead(HttpURLConnection con) pcwkO  
{ __<u!;f  
for(int i=1;;i++) vcTWe$;Q  
{ R r7
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String header=con.getHeaderFieldKey(i); 
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if(header!=null) JbN@AX:%  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); #hvLv  
Utility.log(header+" : "+con.getHeaderField(header)); [!9dA.tF  
else MN1 kR  
break; Ba
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} oo sbf#V  
} o;bK 7D  
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public void splitterStop() YYfX@`\  
{ $OOZ-+8  
bStop = true; J!r,ktO^U?  
} *((wp4b  
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} |^&n\vXv  
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/* za{z2#aJ  
**FileAccess.java i oCoFj  
*//文件访问(定位，写) .
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package NetFox; {;.q?mj  
import java.io.*; ie4keVlXc  
]iu}5]?)  
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public class FileAccessI implements Serializable{ aRFLh  
vd>K=! J  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 #sl_ BC9  
RandomAccessFile oSavedFile; -"J6|Y#8  
long nPos; fBCW/<Z  
,nn5LQ|l.j  
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public FileAccessI() throws IOException gp07I{0~m  
{ WT(inf[  
this("",0); RiHOX&-7  
} ^`b&fbv  
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7P3PQ%:  
public FileAccessI(String sName,long nPos) throws IOException HSq.0vYl6  
{ Z4YQ5O5  
oSavedFile = new RandomAccessFile(sName,"rw"); zJ;K4)"j  
this.nPos = nPos; /18Z4TA  
oSavedFile.seek(nPos); IT,d(UV_  
} T3po.Km\{  
7U=|>)Q0s  
q^{Z"ifL  
public synchronized int write(byte[] b,int nStart,int nLen) HI}$Z=C  
{ JTT"t@__  
int n = -1; x!\FB.h4!(  
try{ M6(oJ*  
oSavedFile.write(b,nStart,nLen); &P8 Run  
n = nLen; `x;8,7W;B  
} 3Cq
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catch(IOException e) 9G8n'jWyY  
{ Q_}i8p'  
e.printStackTrace (); x;H#-^LxW=  
} k<b`v&G  
%9.] bd|%F  
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return n; }@IRReQ  
} oZvQ/|:p!  
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} "BB#[@
 
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/* gv=mz,z  
**SiteInfoBean.java Q;O\tl  
*/ S312h'K j  
package NetFox; `?{Hs+4P5  
COS(pfC  
75Xi%mlE7  
public class SiteInfoBean { A`4Di8'Me  
Ks&~VU  
GD1=Fb"&)  
private String sSiteURL; //Site's URL  &y1' J  
private String sFilePath; //Saved File's Path %N)o*H&  
private String sFileName; //Saved File's Name i<D}"h|  
private int nSplitter; //Count of Splited Downloading File k*b
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<YbOO{  
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public SiteInfoBean() Vv(!Ki}  
{//nSplitter的缺省值为5 5qco4@8  
//default value of nSplitter is 5 9IL#\:d1  
this("","","",5); H[o'j@0  
} 2G"mm(   
x&3!z[m@@  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) R7us9qM4e  
{ s~$kzEtjjU  
sSiteURL= sURL; L1
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sFilePath = sPath; cOUsbxYTD  
sFileName = sName; bo&!oY#  
this.nSplitter = nSpiltter;
P,RCbPC4  
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<[xxCW(2  
} {+f@7^/i.  
=Mq=\T  
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public String getSSiteURL() L>{E8qv>w  
{ lj.z>  
return sSiteURL; c1wM"  
} YZ\$b=-  
,_`\c7@  

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public void setSSiteURL(String value) zW%-Z6%D  
{ ?PWD[mQE\  
sSiteURL = value; +SM $#  
} 3y>
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V_U$JKJ1=  
public String getSFilePath() 9A\J*OU  
{ ,oDZ:"
;  
return sFilePath; xk86?2b{)  
} +8
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;^:~xJFx|  
GZQ)TzR  
public void setSFilePath(String value) >8SX,  
{ ;: Hfkyy]  
sFilePath = value; ksY^w+>(!  
} =(*Eh=Pw  
oypq3V=5  
.D^
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public String getSFileName() >U"f1q*$  
{ Opmb   
return sFileName; !`,6E`Y#  
} u4$d#0sA  
j]J2,J  
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public void setSFileName(String value) 2DTH|Yv  
{ j3`:;'L  
sFileName = value; >?M:oUVDU  
} jb)z[!FbM  
N&S:=x:$S  
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public int getNSplitter() ~n]:f7?I  
{ |Uy hH^  
return nSplitter;
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} w[PW-m^`  
}
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public void setNSplitter(int nCount) 4OCz:t  
{ H
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nSplitter = nCount; BEPDyy  
} K"Nq_Ddwd  
} R9S7p)B  
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/* !SiZA"  
**Utility.java PhKJ#DRbr  
*/ g IX"W;  
package NetFox; _}jj>+zA`  
28X)s!W'  
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public class Utility { ?_\Hv@t;  
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public Utility() x"AYt:ewuc  
{ gADt%K2#Z  
s.zH.q,  
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} zRvYN  
sS5#Q  
//线程睡眠 e yTYg  
public static void sleep(int nSecond) c~RElL  
{ N@Slc 0  
try{ ODv)-J  
Thread.sleep(nSecond); s%4)}w;z  
} ( Y/ DMQ  
catch(Exception e) n)`*{uv$  
{ q;kMeE*  
e.printStackTrace (); Htsa<tF  
} T^A:pL1  
} Zpu>T2Tp  
Mv4JF(,S  
//日志 qViky=/-  
public static void log(String sMsg) +#&2*nY  
{ A FfgGO  
System.err.println(sMsg); &k1Ez  
} Zls4@/\Q  
q%>L/KJ#  
!EpP-bq'*  
public static void log(int sMsg) {R1jysGtD  
{ =9pFb!KX  
System.err.println(sMsg); vj{h*~  
} #exE~@fy-  
} BIcE3}dS8  
$: Qi9N
 
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/* EO'3;mo,  
**TestMethod.java f0wQn09  
*/ sF|<m)Kt{W  
package NetFox; ,qv
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?c>j^}A/N  
.`)IC
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public class TestMethod { Q`19YX  
[HNGTde&  
kk!}mbA_}  
public TestMethod() x5PQ9Bw,  
{ ///xx/weblogic60b2_win.exe CH9#<?l  
try{ NsJUruN  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); )}u.b-Nt.  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); @.CPZT  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 6"A|)fz  
fileFetch.start(); SrHRpxy  
} dnNc,l&
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catch(Exception e){e.printStackTrace ();} v5<Ext rV  
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~^VcTSY@<L  
} ~9'VP}\  
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public static void main(String[] args) ] YQ*mvI]  
{ @p
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new TestMethod(); ld2\/9+n  
} {kZhje^$vi  
} ,VHvQU  
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