http断点续传简单实现（java)

/* Kab"r_'  
**SiteFileFetch.java \6AYx[|  
*/ hB/4.K]8  
package NetFox; a!rU+hiC  
import java.io.*; 
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import java.net.*; |8^53*f ?
 
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art L  
public class SiteFileFetch extends Thread { bQd'objpY  
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SiteInfoBean siteInfoBean = null; //文件信息Bean (%.[MilxPM  
long[] nStartPos; //开始位置 L~9Q7 6w  
long[] nEndPos; //结束位置 5hN)y-4@  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 -Uj)6PzGu  
long nFileLength; //文件长度 SR)jJ=R3  
boolean bFirst = true; //是否第一次取文件 "LZQ1P*ef$  
boolean bStop = false; //停止标志 $>^DkrOd  
File tmpFile; //文件下载的临时信息 %S*<2F9  
DataOutputStream output; //输出到文件的输出流 #o`y<1rN  
i2.g}pM.A  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） LB9D6,*t  
public SiteFileFetch(SiteInfoBean bean) throws IOException khFr%u ?S  
{ IBfLb(I  
siteInfoBean = bean; y2Eq-Ie  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 96G8B62  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); n}0n!Pr^  
if(tmpFile.exists ()) VPOzt7:  
{ V+`gkWe/  
bFirst = false; y,&'nk}  
read_nPos(); HK}br!?  
} 2S%[YR>>  
else |q|?y`X4/  
{ Aw?i6d  
nStartPos = new long[bean.getNSplitter()]; $~)BO_;o  
nEndPos = new long[bean.getNSplitter()]; 'k^d-Mh>h  
} c,@&Z#IZ`  
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} \vg(@)$q   
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public void run() @6["A'h  
{ *LuR <V  
//获得文件长度 Uk1|y\  
//分割文件 v@,n]"  
//实例FileSplitterFetch }+mIP:T  
//启动FileSplitterFetch线程 #BPJRNXd  
//等待子线程返回 eR1SPS1+  
try{ (U_`
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if(bFirst) vbA<=V*P  
{ Kd='l~rby  
nFileLength = getFileSize(); JRgrg
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if(nFileLength == -1) |)TI&T;k  
{ "Yp:{e  
System.err.println("File Length is not known!"); f%,Vplb  
} %<dvdIB  
else if(nFileLength == -2) TEJn;D<1I,  
{ I1f4u6\*X  
System.err.println("File is not access!"); }xx"  
} ,5*Z<[*  
else /$[9-G?  
{ [|qV*3|?  
for(int i=0;i<nStartPos.length;i++) ;-0 d2Z  
{ Ga<U
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); Ow"e3]}Mt  
} }>93X0%r  
for(int i=0;i<nEndPos.length-1;i++) 4 H<.  
{ R!)3{cjU@  
nEndPos = nStartPos[i+1]; nu(;yIRP  
} Ppton+?(  
nEndPos[nEndPos.length-1] = nFileLength; mV>l`&K=  
} ()}(3>O-  
} '@0Z#A  
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//启动子线程 rtSG-_[i  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; d/&W[jJ  
for(int i=0;i<nStartPos.length;i++) a^vTBJXo  
{ s!IX3rz  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), APgjT';P^  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), NZb}n`:  
nStartPos,nEndPos,i); "1P[D'HV4|  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); %~e+H|  
fileSplitterFetch.start(); )k^y<lC2a  
} '^|u\$&U  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),  g)Tr#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); <(Rbu2_  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", :~^_*:  
nEndPos = " + nFileLength); vZiuElxKi  
// fileSplitterFetch[nPos.length-1].start(); K0aT(Rc e  
:kMF.9U:  
W(jOD,QM
B  
//等待子线程结束 }/bxe0px  
//int count = 0; 1agNwFd~  
//是否结束while循环 FG:t2ea  
boolean breakWhile = false; yR3pK 0Y(?  
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while(!bStop) p3,m),  
{ Hk8lHja+\  
write_nPos(); JW},7Ox  
Utility.sleep(500); En9>onJ  
breakWhile = true; {Mpx33  

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for(int i=0;i<nStartPos.length;i++) 0f5c#/7C9  
{ %y
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if(!fileSplitterFetch.bDownOver) rD;R9b"J  
{ C+L_f_6]  
breakWhile = false; *t{^P*pc  
break; ^`S.Mw.  
} f6,?Yex8B  
} 29HyeLB@  
if(breakWhile) oh
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break; -Hh.8(!XoO  
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//count++; )61X,z  
//if(count>4) ],~H3u=s3  
// siteStop(); h'nXV{N0  
} 8B`w!@hf  
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System.err.println("文件下载结束！"); 0z$::p$%u  
} i
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catch(Exception e){e.printStackTrace ();} $KVCEe!X  
} `%/w0,0  
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|jB/d@RE  
//获得文件长度 R=J5L36F  
public long getFileSize() P:>]a$Is  
{ 5S*aZ1t18  
int nFileLength = -1; $DlO<  
try{ Q_)$Ha{>H,  
URL url = new URL(siteInfoBean.getSSiteURL()); r>ag(^J\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); D0}r4eA  
httpConnection.setRequestProperty("User-Agent","NetFox"); kQ`p\}7_  
:Vy*MPS5  

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int responseCode=httpConnection.getResponseCode(); G3o`\4p  
if(responseCode>=400) n52Q-6H  
{ $jOp:R&I^3  
processErrorCode(responseCode); r+!29  
return -2; //-2 represent access is error hCb2<_3CR  
} Z,oC
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String sHeader;
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for(int i=1;;i++) VfFbZds8f  
{ $H`{wJ?2(  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); KPAvNM  
//Utility.log(in.readLine()); sDB,+1"Y$  
sHeader=httpConnection.getHeaderFieldKey(i); v
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if(sHeader!=null) |=:<[FU  
{ 9&
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if(sHeader.equals("Content-Length")) C~IE_E&Q`  
{ f@ILC=c<  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ,u=+%6b)A  
break; zHKx,]9b  
} 7]_zWx,r  
} "r~/E|Da<  
else ffMk.Sq
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break; je`Inn<  
} Ro_jf

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} Z7NR%u_|[  
catch(IOException e){e.printStackTrace ();} -zzoz x]S=  
catch(Exception e){e.printStackTrace ();} %NDr5E^cc  
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Utility.log(nFileLength); ZfXgVTJ`  
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return nFileLength; Us.k,  
} Ae%AG@L  
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//保存下载信息（文件指针位置） 8#w%qij  
private void write_nPos() ME66B
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{ ";;!c.!^  
try{ of {K{(M7@  
output = new DataOutputStream(new FileOutputStream(tmpFile)); "A> _U<Y  
output.writeInt(nStartPos.length); \ B'AXv6  
for(int i=0;i<nStartPos.length;i++) G+&p
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{ 0g;)je2_2?  
// output.writeLong(nPos); Z]w?RL  
output.writeLong(fileSplitterFetch.nStartPos); |\>Ifv%{  
output.writeLong(fileSplitterFetch.nEndPos); 1ASoH,D/  
} ?AH B\S  
output.close(); l.P;85/+  
} IL1iTRH  
catch(IOException e){e.printStackTrace ();} tAPf#7{|   
catch(Exception e){e.printStackTrace ();} _'4S1  
} ^#XQ2UN  
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//读取保存的下载信息（文件指针位置） cTq;<9Iew  
private void read_nPos() 3~{0X-  
{ DJ9x?SL@KD  
try{ 1IlOU|
4  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); PuhvJHT  
int nCount = input.readInt(); Omi/sKFMi  
nStartPos = new long[nCount]; I9dX\w}  
nEndPos = new long[nCount]; X:lStO#5  
for(int i=0;i<nStartPos.length;i++) Y^nm{;G+  
{ GKKDO+A=!  
nStartPos = input.readLong(); tyWDa$u,u  
nEndPos = input.readLong();  d0i|^  
} &KY!a0s  
input.close(); a;v4R[lQ  
} F+ 7*SImv6  
catch(IOException e){e.printStackTrace ();} +&dkJ 4g[  
catch(Exception e){e.printStackTrace ();} h?H|)a<^9  
} O~v~s 'c&  
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private void processErrorCode(int nErrorCode) f-634KuP  
{ !
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System.err.println("Error Code : " + nErrorCode); K9]zUe&#w  
} fZ&' _  
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//停止文件下载 (tX)r4VU  
public void siteStop() 0yv
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{ :wN!E{0j  
bStop = true; 1Vx5tOq  
for(int i=0;i<nStartPos.length;i++) 1J72*`4OK  
fileSplitterFetch.splitterStop(); S;y4Z:!  
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} r6R@"1/  
} c-v-UO%  
//负责部分文件的抓取 L^zh|MEyzk  
**FileSplitterFetch.java hsT&c|  
*/ }dHdy{$  
package NetFox; ?z <-Ww  
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import java.io.*; `23][V  
import java.net.*; 9UVT]acq  
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public class FileSplitterFetch extends Thread { IibYGF  
,QpFVlPU  
gWoUE7.3`  
String sURL; //File URL <5,|h3]-#  
long nStartPos; //File Snippet Start Position ]31=8+D  
long nEndPos; //File Snippet End Position Y9>92#aME  
int nThreadID; //Thread's ID !%D';wQ,/  
boolean bDownOver = false; //Downing is over !nvg:$.&  
boolean bStop = false; //Stop identical x}nBUq:  
FileAccessI fileAccessI = null; //File Access interface Z1:%AqxP  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ji ./m8(  
{ G~v:@  
this.sURL = sURL; ~;a\S3  
this.nStartPos = nStart; \gB~0@[\7  
this.nEndPos = nEnd; #r]Z2Y]  
nThreadID = id; w^ OB  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 096Yd=3h  
} |q8N$m  
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public void run() }]PHE(}7  
{ \D(3~y>  
while(nStartPos < nEndPos && !bStop) 1^2Q`~,g  
{ <nN.$4~X  
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try{ # =tw ,S  
URL url = new URL(sURL); ,a
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); )5LT!14  
httpConnection.setRequestProperty("User-Agent","NetFox"); (3lA0e`Y  
String sProperty = "bytes="+nStartPos+"-"; HKJBR)T  
httpConnection.setRequestProperty("RANGE",sProperty); S2;^  
Utility.log(sProperty); VgOD
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'?mF,Co{  
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InputStream input = httpConnection.getInputStream(); ]X77?Zz9  
//logResponseHead(httpConnection); DKu$u]Z  
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byte[] b = new byte[1024]; fn=A_ i  
int nRead; kHylg{i{"  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) d+,!p8Q  
{ ;nP(S`'  
nStartPos += fileAccessI.write(b,0,nRead); "n`z`{<n  
//if(nThreadID == 1) <<CWN(hQWO  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); j&_>_*.y  
} yDK
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7/51_=%kR  
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Utility.log("Thread " + nThreadID + " is over!"); pR93T+X  
bDownOver = true; NWvIwt{  
//nPos = fileAccessI.write (b,0,nRead); _<FUS'"  
} J sz=5`  
catch(Exception e){e.printStackTrace ();} g:a[N%[C  
} W h
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} ;"x+V gS'  
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//打印回应的头信息 q%e'WMG~n  
public void logResponseHead(HttpURLConnection con) H~nX!sO  
{ uJ -$i  
for(int i=1;;i++) ?%UiW7}j';  
{ oJr+RO  
String header=con.getHeaderFieldKey(i); p|2GPrA]aL  
if(header!=null) [B+F}Q^;  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 6>rz=yAM_  
Utility.log(header+" : "+con.getHeaderField(header)); U364'O8_  
else m^!j)\sM5  
break; ufIv
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} Cj-&L<  
} 1:](=%oM&k  
(k #xF"yI  
t^"8M6BqC;  
public void splitterStop() v$Fz^<Na  
{ T`fT[BaY  
bStop = true; #jg-q|nd  
} ,^8':X"A{!  
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} <I34@;R c  
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/* _$c o Y  
**FileAccess.java .,xyE--;d  
*//文件访问(定位，写) 3kC|y[.
&  
package NetFox; x4c|/}\)*  
import java.io.*; aYT!xdCI  
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public class FileAccessI implements Serializable{ UHvA43  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 7)jN:+4N  
RandomAccessFile oSavedFile; 6[k<&;  
long nPos; TS9<uRO0  
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public FileAccessI() throws IOException F&R*njJcc  
{ /\-}-"dm  
this("",0); y!P!Fif'  
} SR?mSpq5  
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public FileAccessI(String sName,long nPos) throws IOException o/o6|[=3  
{ :G@z?ZJ[  
oSavedFile = new RandomAccessFile(sName,"rw"); :cWU,
V  
this.nPos = nPos; 5["3[h  
oSavedFile.seek(nPos); 5uQ+'*xN%  
} c.Hw K\IU  
?# FYF\P  
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public synchronized int write(byte[] b,int nStart,int nLen) GJcxqgk$  
{ XH~(=^/_  
int n = -1;  4bA^Gq  
try{ 7:?\1a  
oSavedFile.write(b,nStart,nLen); FqA4 OU  
n = nLen; %AA&n*m  
} ]b%U9hmL^f  
catch(IOException e) ZN$%\,<  
{ b`D]L/}pr  
e.printStackTrace (); v:4j3J$z  
} ; >H1A  
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return n; d=^QK{8  
} Pb?vi<ug+  
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} mN]WjfII  
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/* -fFtHw:kHh  
**SiteInfoBean.java =hvPq@C%  
*/ 9n\>Yieu  
package NetFox; 2sIt~ Gn  
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public class SiteInfoBean { [%bGs1U  
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private String sSiteURL; //Site's URL }Mt
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private String sFilePath; //Saved File's Path 0)d='3S  
private String sFileName; //Saved File's Name _LwF:19Il  
private int nSplitter; //Count of Splited Downloading File rHw#<oV  
3#t#NW*e  
fEL 9J{  
public SiteInfoBean() n46!H0mJ  
{//nSplitter的缺省值为5 H~s8M  
//default value of nSplitter is 5 <L4$f(2  
this("","","",5); 3S+9LOrhY  
} PF/K&&9}
 
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) f4P({V  
{ a`xAk^w+  
sSiteURL= sURL; O$6&4p*F.  
sFilePath = sPath; !hq*WtIk  
sFileName = sName;
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this.nSplitter = nSpiltter; D#1R$4M=  
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} njxLeDe-  
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public String getSSiteURL() H5Eso*v@  
{ ZN)EbTpc\a  
return sSiteURL; J/e]
  
} Wx]Xa]-  
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public void setSSiteURL(String value) ;: _K,FU  
{ =U*D.p*%f  
sSiteURL = value; i#b/.oa  
} a-|pSe*rx  
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\7b, Mz!  
public String getSFilePath() [k%hl`}  
{ Wj,s/Yr:  
return sFilePath; R&Nl!QTJj  
} H@@ 4n%MK  
\B~g5}=  
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public void setSFilePath(String value) f:+/=MW  
{ uc+{<E3,%  
sFilePath = value; q]OIP"yv  
} >R]M:Wx  
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public String getSFileName() GgY8\>u  
{ #fa,}aj  
return sFileName; ;GG,Z#\m  
} c|.te]!ds  
rmA?Xlh\  
d*{Cv2A.  
public void setSFileName(String value) <!RkkU& 6  
{ 34!.5^T  
sFileName = value; W !j-/ql  
} yC
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{p1`[R&n#  
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public int getNSplitter() &J2UAmB  
{ s9sl*1n1m`  
return nSplitter; FtyT:=Kpc  
} |#o' =whTl  
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4Pc-A  
public void setNSplitter(int nCount) wJ2cAX;"  
{ nE8z1hBUq  
nSplitter = nCount; "|Q.{(|kO1  
} 1ygEyC[1  
} G(wK(P0j  
BH {z
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QD!NV*  
/* 9dA+#;?  
**Utility.java <rgK}&q  
*/ hOk
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package NetFox; ,e'm@d$Q*  
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public class Utility { G3TS?u8Q  
3?V'O6  
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public Utility() JR]elRR  
{ 0=HB!{@  
%HpPTjAW  
}:faHLYT  
} N}U+K  
]dGH i \  
//线程睡眠 0'*{BAWx  
public static void sleep(int nSecond) ]*| hd/j  
{ 9*I[q[>9  
try{ uQdH():  
Thread.sleep(nSecond); z{OL+-OY  
} B(Yg1jAe  
catch(Exception e) z8a{M$-Q
 
{ 3LfF{ED@  
e.printStackTrace (); m]U  
} KdozB!\  
} `&c[s%0  
agwbjkU/  
//日志 7WmLC  
public static void log(String sMsg) Q +l{> sL  
{ (v?@evQ  
System.err.println(sMsg); E va&/o?P|  
} aB~k8]q.  
 m,+PYq  
9
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public static void log(int sMsg) I>.pkf<V  
{ 
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System.err.println(sMsg); BEb?jRMjLg  
} Xxh^4vKjX  
}
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=Ks&m4  
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/* UeCi{W  
**TestMethod.java JzN "o'  
*/ WDxcV%  
package NetFox; yWZ_  
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public class TestMethod { 'Y2$9qy-L  
XHJdynt/  
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public TestMethod() *bpN!2  
{ ///xx/weblogic60b2_win.exe E7h@Y~bNhW  
try{ N:3=G`Ws  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); <#BK(W~$  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); y]{b4e  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ?yAb=zI1b  
fileFetch.start(); A*0X~6W  
} K3:z5j.X  
catch(Exception e){e.printStackTrace ();} ]~ N.  
"Fmq$.$%  
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} *sp")h#Z  
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/>Zfx.Aj6  
public static void main(String[] args) &#C&0f8PnD  
{ r|}Pg}O  
new TestMethod(); )( 3)^/Xz  
} t9<BQg  
} }!fIY7gv  
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