http断点续传简单实现（java)

/* ZdlQ}l#F  
**SiteFileFetch.java ' BY|7j~  
*/ Tua#~.3}J  
package NetFox; }Io5&ww:U  
import java.io.*; eV\VR !!i  
import java.net.*; U,V+qnS  
*rmM2{6  
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public class SiteFileFetch extends Thread { Wux[h8G  
 uE'Kk8  
C /w]B[H  
SiteInfoBean siteInfoBean = null; //文件信息Bean *#j_nNM4  
long[] nStartPos; //开始位置 -EG=}uT['b  
long[] nEndPos; //结束位置 _*n 4W^8  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 k; n
ed  
long nFileLength; //文件长度 }r|$\ms  
boolean bFirst = true; //是否第一次取文件 qsdgG1<  
boolean bStop = false; //停止标志 |)%;B%  
File tmpFile; //文件下载的临时信息 V(0V$&qipc  
DataOutputStream output; //输出到文件的输出流 g1&q6wCg|  
> mEB,  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） vvF]g.,  
public SiteFileFetch(SiteInfoBean bean) throws IOException pQk@ +r  
{ {GG;/Ns{f-  
siteInfoBean = bean; '1b4nj|<m  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); okH*2F(-  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); VJgYXPE `  
if(tmpFile.exists ()) Rg 5kFeS  
{ #pk  
bFirst = false; 5RR4jX]  
read_nPos(); ageTv/  
} qb+Gjgp  
else g])iU9)8  
{ #O!gjZ,  
nStartPos = new long[bean.getNSplitter()]; jAfqC@e  
nEndPos = new long[bean.getNSplitter()]; `( _N9.>B  
} `W2 o~r*&  
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} w-LaSJ(T  
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public void run() iIc/%< ;  
{ %nyZ=&u  
//获得文件长度 $8>II0C.  
//分割文件 ,&s%^I+CC  
//实例FileSplitterFetch -(9TM*)O  
//启动FileSplitterFetch线程 a6 w'.]m  
//等待子线程返回 9z7rv,  
try{ Cps'l  
if(bFirst) f'OcW*t  
{ K6N+0#  
nFileLength = getFileSize(); 1'b}Y8YO  
if(nFileLength == -1) 63c\1]YB.  
{ S%3&Y3S  
System.err.println("File Length is not known!"); !&R|P|7qN}  
} a=M/0N{!  
else if(nFileLength == -2) 8j}o\!H  
{ 4c@_u
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System.err.println("File is not access!"); VCa`|S?2  
} YD] :3!MI  
else +$#ytvDy  
{
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for(int i=0;i<nStartPos.length;i++) \ `|  
{ r>J%Eu/O  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); !YX_k<1E  
} 9}'92  
for(int i=0;i<nEndPos.length-1;i++) S.!K  
{ C9n*?Mk:  
nEndPos = nStartPos[i+1]; a!\^O).pA  
} S+GW}?!  
nEndPos[nEndPos.length-1] = nFileLength; CRu {Ie5B  
} (= Wu5H  
} =,Z5F`d4  
VbX$\Cs:  
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//启动子线程 QI`&N(n  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; uLrZl0%HT~  
for(int i=0;i<nStartPos.length;i++) d^I:{Ii'  
{ c=33O,_  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Z
5,"KhB]  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ^tI4FQ>Y  
nStartPos,nEndPos,i); x]vyt}oCmk  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Q$A;Fk}-  
fileSplitterFetch.start(); YqYobL*q/  
} k\A4s
j  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), jfpbD /  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); E6#")2C~  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", lfqsoIn;  
nEndPos = " + nFileLength); /~pB_l  
// fileSplitterFetch[nPos.length-1].start(); C;oO=R3r  
e(vnnv?R{  
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//等待子线程结束 *kt%.wPJ  
//int count = 0; fr8hT(,s)  
//是否结束while循环 ;n.SRy6
 
boolean breakWhile = false; X 1}U  
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while(!bStop) eOJ_L]y-  
{ `bW0Va N  
write_nPos(); /@0  
Utility.sleep(500); <"nF`'olV  
breakWhile = true; (>`S{L C>s  
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for(int i=0;i<nStartPos.length;i++) L[MAc](me-  
{ 1aoKf F(  
if(!fileSplitterFetch.bDownOver) n_4BNOZ~  
{ F **/T  
breakWhile = false; nKe|xP  
break; 6NGQU%Hd  
} C@ "l"  
} )TwA?kj  
if(breakWhile) _g6H&no[  
break; k]S`A,~  
;TboS-Y  
56H~MnX  
//count++; wN:vI(C  
//if(count>4) sq+cF/jo6  
// siteStop(); 
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} )npvy>C'(  
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9XX:_9|I  
System.err.println("文件下载结束！"); '3TfW61]  
} IY}{1[<N  
catch(Exception e){e.printStackTrace ();} _vUId?9@+e  
} #-kx$(''V  
|j}%"wOh  
pPJE.[)V/  
//获得文件长度 A{)p#K8  
public long getFileSize() $|7;(2k  
{ eNr2-R  
int nFileLength = -1; vUB*Qm]Y\  
try{ 'S6JpWG1  
URL url = new URL(siteInfoBean.getSSiteURL()); @-XMox/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); LcGG~P|ML  
httpConnection.setRequestProperty("User-Agent","NetFox"); vue=K  
WTUC\}#E\  
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int responseCode=httpConnection.getResponseCode(); /m h #o  
if(responseCode>=400) ?y,z  
{ /<CgSW}  
processErrorCode(responseCode); lLN5***47J  
return -2; //-2 represent access is error J['i  
} Xe@:Aun  
c? >;UzM  
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String sHeader; %APeQy"6#^  
wa
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for(int i=1;;i++) `9nk{!X\  
{ AP0z~
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); X9o6} %Y  
//Utility.log(in.readLine()); \6vr)1~N>  
sHeader=httpConnection.getHeaderFieldKey(i); p s_o:*$l  
if(sHeader!=null) #Wely~  
{ @%I-15Jz  
if(sHeader.equals("Content-Length")) j0A9;AP;;C  
{ CMU\DO  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); .`/6[Zp

 
break; c='uyx  
} '(SqHP|8&g  
} \{a 64  
else )uy2,`z  
break; y@Ak_]{b  
} 2(2
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} ABU~V+'2  
catch(IOException e){e.printStackTrace ();} =[YjIWr#o  
catch(Exception e){e.printStackTrace ();} B0m2SUC,H  
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Utility.log(nFileLength); 1.z]/cx<y  
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9
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return nFileLength; =S|dzgS/  
} !z"nJC  
/C/I_S}H  
?J28@rM  
//保存下载信息（文件指针位置） YkI_i(  
private void write_nPos() hd#MV!ti  
{ U2*kuP+n  
try{ )CG,Udu  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Us4#O&  
output.writeInt(nStartPos.length); o=Ia{@  
for(int i=0;i<nStartPos.length;i++) 7-4S'rq+  
{ *iXaQuT  
// output.writeLong(nPos); DUvF  
output.writeLong(fileSplitterFetch.nStartPos); C$^WW}S  
output.writeLong(fileSplitterFetch.nEndPos); AO]1`b:  
} 7X/KQ97  
output.close(); ZW`wA2R0   
} 1_5]3+r_U-  
catch(IOException e){e.printStackTrace ();} b}Wm-]|+  
catch(Exception e){e.printStackTrace ();} husk\  
} H*h4D+Kxv  
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Z1R{'@Y0Z  
//读取保存的下载信息（文件指针位置） ,W5!=\Gg(  
private void read_nPos() z;Dc#SZnO(  
{ lBNB8c0e"{  
try{ '?qI_LP?  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 7>xfQ  
int nCount = input.readInt(); g!
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nStartPos = new long[nCount]; U
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nEndPos = new long[nCount]; k:*vD"  
for(int i=0;i<nStartPos.length;i++) gi<%: [jT  
{
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nStartPos = input.readLong(); <L:}u!  
nEndPos = input.readLong(); mEq>{l:  
} 'rSJ9Mw"x  
input.close();    
} nD#uOep9  
catch(IOException e){e.printStackTrace ();} _TjRvILC  
catch(Exception e){e.printStackTrace ();} G!g];7PG(  
} RBV*e9P%  
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private void processErrorCode(int nErrorCode) eD0|6P;Ei  
{ xv0y?#`z  
System.err.println("Error Code : " + nErrorCode); zI.:1(,  
} =iE)vY,?"}  
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//停止文件下载 !X+}W[Ic^  
public void siteStop() 3'6by!N,d  
{ i#(+Kxr]>  
bStop = true; Y>I9o)KR  
for(int i=0;i<nStartPos.length;i++) 30Udba+{]p  
fileSplitterFetch.splitterStop(); |snWO0iF  
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} IZ9* '0Z  
} %Hy.  
//负责部分文件的抓取 *a@78&N  
**FileSplitterFetch.java $fQ'q3  
*/ =7Sw29u<  
package NetFox; pzcof#2  
{/K!cPp9  
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import java.io.*; gv/yfiA?  
import java.net.*; RKwuvVI  
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public class FileSplitterFetch extends Thread {
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/[UuHU5*R  
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String sURL; //File URL .MW/XnCYs4  
long nStartPos; //File Snippet Start Position ]QmY`pT
B`  
long nEndPos; //File Snippet End Position 1owe'7\J  
int nThreadID; //Thread's ID Ct386j><  
boolean bDownOver = false; //Downing is over 884-\M"h  
boolean bStop = false; //Stop identical ;Wig${  
FileAccessI fileAccessI = null; //File Access interface ~uh,R-Q$  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException wo_iCjmK  
{ L?r\J8Ch<  
this.sURL = sURL; p@%H. 5&&  
this.nStartPos = nStart; Y$nI9  
this.nEndPos = nEnd; <M M(Z  
nThreadID = id; ?D=t:=  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 rlXMrn  
} xqzB=0  
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}Fb966 $  
public void run() <*5`TE0J  
{ yI8 /m|  
while(nStartPos < nEndPos && !bStop) mM-7 jz  
{ T*zy^we  
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try{ bXK$H=S Bz  
URL url = new URL(sURL); *sq+ Vc(  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); UszR. Z  
httpConnection.setRequestProperty("User-Agent","NetFox"); K]yUPx  
String sProperty = "bytes="+nStartPos+"-"; `d!~)D  
httpConnection.setRequestProperty("RANGE",sProperty); +*KDtqZjk  
Utility.log(sProperty); x*0mmlCb  
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InputStream input = httpConnection.getInputStream(); lv\^@9r  
//logResponseHead(httpConnection); ]M/*Beh  
6|ENDd[  
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byte[] b = new byte[1024]; =pn(5
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int nRead; }d16xp  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0A.9<&Lod  
{ W0KSLxM  
nStartPos += fileAccessI.write(b,0,nRead); E?F?)!%  
//if(nThreadID == 1) rI4N3d;C  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _43 :1!os  
} zq4)Uab*  
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Utility.log("Thread " + nThreadID + " is over!"); JsbH'l  
bDownOver = true; (Q ~<>  
//nPos = fileAccessI.write (b,0,nRead); ZIvP?:=!  
} 6D1tRo  
catch(Exception e){e.printStackTrace ();} {b90c'8?a  
} i-31Cxb  
} p$bR M`R&s  
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6%2\bI.#  
//打印回应的头信息 )}5f'TK  
public void logResponseHead(HttpURLConnection con) ?\Lf=[  
{ b'TkYa^  
for(int i=1;;i++) 5.FAuzz  
{ {^SHIL  
String header=con.getHeaderFieldKey(i); !-Md+I_  
if(header!=null) n<66 7 <  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ,: 4+hJ<q  
Utility.log(header+" : "+con.getHeaderField(header)); C}cYG  
else R#33ACCX  
break; il>XV>  
} 6sl2vHzA  
} L+d4&x  
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public void splitterStop() xgv&M:%D-  
{ Gt5'-Hyo  
bStop = true; Kgu#Mi~  
} - ]Mp<Y  
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} %eLf6|1x  
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/* Hp?uYih0  
**FileAccess.java 8i'EO6  
*//文件访问(定位，写) CAV Q[r5y  
package NetFox; zwp
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import java.io.*; ?&GV~DYxA  
!L\P.FP7b  
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public class FileAccessI implements Serializable{ 34Z$a{ w  
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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 aO>Nev  
RandomAccessFile oSavedFile; >KMTxHE`+  
long nPos; K18Sj,]B  
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public FileAccessI() throws IOException !'T,%8']  
{ EHY}gG)  
this("",0); @8s:,Y_  
} QR]61v:`  
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public FileAccessI(String sName,long nPos) throws IOException [d/uy>z,  
{ @I,:(<6  
oSavedFile = new RandomAccessFile(sName,"rw"); Ve\=By-a|  
this.nPos = nPos; 1!`B8y)  
oSavedFile.seek(nPos); 4Hcds9y9  
} mzh7E[S_,i  
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public synchronized int write(byte[] b,int nStart,int nLen) dqo&3^px  
{ A%
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int n = -1; cl3Dwrf?  
try{ -McDNM
 
oSavedFile.write(b,nStart,nLen); j[y,Jch  
n = nLen; v a j
 
} q&N1| f7  
catch(IOException e) I&Y9  
{ li Hz5<|  
e.printStackTrace (); p^ojhrr  
} '}eA2Q>BV  
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return n; Da8{==  
} ~*,e&I  
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} Fi*j}4F1  
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,  
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/* r%DaBx!x8  
**SiteInfoBean.java jVhfpS[  
*/ =ijVT_|u0  
package NetFox; )RE~=*?d  
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public class SiteInfoBean { ,Xt!dT-  
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private String sSiteURL; //Site's URL >s+TD4OfY  
private String sFilePath; //Saved File's Path 1}"PLq(  
private String sFileName; //Saved File's Name x%\m/_5w%  
private int nSplitter; //Count of Splited Downloading File Kgw_c:/'  
s$ v<p(yl  
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public SiteInfoBean() G)'(%rl  
{//nSplitter的缺省值为5 ;$= GrR  
//default value of nSplitter is 5 |w7D&p$  
this("","","",5); N)H _4L  
} ek3,ss3  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 21
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{ Oe^oigcM  
sSiteURL= sURL; PC3-X['[  
sFilePath = sPath; -6./bB g  
sFileName = sName; 5o dtYI%L  
this.nSplitter = nSpiltter; wmf#3"n  
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} Jm(sx'qPx  
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public String getSSiteURL() C)|{7W  
{ $6 A91|ZSQ  
return sSiteURL; a6vls]?  
} uNcE_<  
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public void setSSiteURL(String value) -P5M(Rt  
{ O%n=n3  
sSiteURL = value; cA8"Ft{P)  
} HLnizE  
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public String getSFilePath() %G%D[ i]  
{ NgXV|)L  
return sFilePath;  b jq1",  
} vid(^2+  
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public void setSFilePath(String value) 2]f"(X4jp  
{ (.DX</f/4  
sFilePath = value; %!;6h^@
 
} x$
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tbP ;iK'  
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public String getSFileName() ~!Q\\_  
{ lN-[2vT<  
return sFileName; !]-ET7  
} X+*"FKm S.  

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w 
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public void setSFileName(String value) /`j~r;S  
{ WF.y"{6>  
sFileName = value; {hLS,Me  
} )G">7cg;t  
\?9{H6<=  
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public int getNSplitter() sP+Z
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{ JN Ur?+g  
return nSplitter; # [0>wEq  
} v^;%Fz_Dr  
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50S >`qi2x  
public void setNSplitter(int nCount) =n}+p>\s  
{ u=5~^ 9  
nSplitter = nCount; %Z"I=;=nxI  
} #CaT0#v  
} y_=},a  
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MJ
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/* u{-J?t&`  
**Utility.java ]} + NT  
*/ :]viLw\&g  
package NetFox; AxOn~fZ!  
hu G]kv3F:  
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public class Utility { 6IVa(;  
;3D[[
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,/qS1W(  
public Utility() D\Nhq Vw  
{ A{!D7kwTz~  
!P6\-.  
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} .\?)O+J!  
UUlrfur~  
//线程睡眠 j0LA  
public static void sleep(int nSecond) z}" Xt=G?  
{ &mM[q'V  
try{ 2[Ja|W\If  
Thread.sleep(nSecond); km]RrjRp  
} k3/V$*i,1b  
catch(Exception e) $
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{ Xiyh3/%yy  
e.printStackTrace (); jE!W&0  
} Q+O3Wgjy  
} 5Z`9L|3d  
.mse.$TK.^  
//日志 w<3g1n7R  
public static void log(String sMsg) vPV=K+1  
{ q0oNRAvn"  
System.err.println(sMsg); 1i.t^PY  
} nI-^  
;JK!dzi}  
<oE(I)r4,  
public static void log(int sMsg) UY
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{ 4;*o}E  
System.err.println(sMsg); {hr+ENgV  
} Wa8?o~0"L  
} @"6dq;"  
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m|RA@sY%`  
/* p.gaw16}>  
**TestMethod.java gX}(6RP_!  
*/ Y+k)d^6r  
package NetFox; &wlSOC')j  
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public class TestMethod { Sc<%$ Gd  
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w2!5Cb2  
public TestMethod() Kh!h_  
{ ///xx/weblogic60b2_win.exe f2sv$#'  
try{ -m&8SN  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ]"3(UKx  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); +,xl_,Z6  
SiteFileFetch fileFetch = new SiteFileFetch(bean); |kHPk)}I]  
fileFetch.start(); vKzq7E  
} .}}w@NO  
catch(Exception e){e.printStackTrace ();} F
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50:$km\  
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} a!1\,.  
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public static void main(String[] args) BPoY32d"_  
{ F+Qp mVU  
new TestMethod(); H+]>*^'8  
} +%$'(ts  
} vGK'U*gGD  
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