http断点续传简单实现（java)

/* WVeNO,?ytS  
**SiteFileFetch.java +DRt2a#  
*/ 1;/SXJ s  
package NetFox; b;VI
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import java.io.*; ''9]`B,:a0  
import java.net.*; G%sO{k7  
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public class SiteFileFetch extends Thread { OH>.N"IG  
9^!.!%6O$  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ;((t|  
long[] nStartPos; //开始位置 'KjH|u  
long[] nEndPos; //结束位置 XdJD"|,h  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 t#.}0Te7  
long nFileLength; //文件长度 iOZ9A~Ywy  
boolean bFirst = true; //是否第一次取文件 dLYM )-H`>  
boolean bStop = false; //停止标志 ,&,%B|gT]  
File tmpFile; //文件下载的临时信息 ) 'xyK  
DataOutputStream output; //输出到文件的输出流 *R+M#l9D`  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） (/uN+  
public SiteFileFetch(SiteInfoBean bean) throws IOException H}r]j\  
{ h>bjG  
siteInfoBean = bean; 2;sTSGDG  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); %/3+
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); >c0leT  
if(tmpFile.exists ()) d9JAt-6z2  
{ RP2$(%  
bFirst = false; O.FTToh<  
read_nPos(); gba1R  
} _t-6m2A  
else 3YLK?X8  
{ P1
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nStartPos = new long[bean.getNSplitter()]; drAJ-ii  
nEndPos = new long[bean.getNSplitter()]; !!L'{beF  
} 6|p8_[e`  
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} N_ ODr]L  
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public void run() /HUT6B  
{ q2xAx1R`sV  
//获得文件长度 iY`[dsT  
//分割文件 #q:j~4)h  
//实例FileSplitterFetch eY`z\I  
//启动FileSplitterFetch线程 EJ {vJZO  
//等待子线程返回 pImq<Z  
try{ U`) ";WN  
if(bFirst) s>L-0vG  
{ <q'?[aKv
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nFileLength = getFileSize();  zr ez*  
if(nFileLength == -1) ;L:UYhDbUx  
{ oTvg%bX  
System.err.println("File Length is not known!"); z@UH[>^gj  
} @wD#+Oz  
else if(nFileLength == -2) O)^F z:  
{ kR1 12J9P  
System.err.println("File is not access!"); ]foS.D,  
} ,sj(g/hg  
else ?6*\M  
{ `%|3c  
for(int i=0;i<nStartPos.length;i++) 1?)h-aN  
{ %ly&~&0  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); bo/U5p
 
} R}(Rv3>Xx  
for(int i=0;i<nEndPos.length-1;i++) uLv  
{ .
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nEndPos = nStartPos[i+1]; R1hmJ  
} A]iT uu5p  
nEndPos[nEndPos.length-1] = nFileLength; k
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} elM<S3  
} 1WaQWZ:=  
dgQ<>+9]6  
@RB^m(> 5  
//启动子线程 !gyW15z'  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; '~yxu$aK  
for(int i=0;i<nStartPos.length;i++) O\q6T7bfRW  
{ !*DYdqQ/  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), M.SF}U  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 0XljFQ  
nStartPos,nEndPos,i); .`KzA]&#  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); \|vo@E  
fileSplitterFetch.start(); p}~Sgi  
} KY2z)#/  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), cC9Zc#aK  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 9[~.{{Y  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", nIOSP:'>  
nEndPos = " + nFileLength); ~W"@[*6w  
// fileSplitterFetch[nPos.length-1].start(); a-#$T)mmfj  
L  
i%i s<'  
//等待子线程结束 v\(6uej^  
//int count = 0; +bso4 }
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//是否结束while循环 q+qF;7dN@  
boolean breakWhile = false; [fwk[qFa  
tw 3zw`o:  
owa&HW/_  
while(!bStop) sOz {spA  
{ H9;IA>  
write_nPos(); uQ ]ZMc  
Utility.sleep(500); <QgpePyoN  
breakWhile = true; sc-+?i  
t\:=|t,  
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for(int i=0;i<nStartPos.length;i++) y'6lfThT  
{ |d\1xTBLp  
if(!fileSplitterFetch.bDownOver) ME>Sh~C\  
{ n[;)(  
breakWhile = false; C!K&d,M  
break; YajAz5N  
} ( ?e Et&  
} jU 3ceXV  
if(breakWhile) [g@Uc  
break; N.|zz)y  
mDt!b6N/  
]#S<]vA  
//count++; 18j>x3tn  
//if(count>4) Jzp|#*~$E  
// siteStop(); $BLd>gTzmv  
} E>|fbaN-%  

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System.err.println("文件下载结束！"); mq}uq9<  
} o=zl{tZV  
catch(Exception e){e.printStackTrace ();} wqjR-$c  
} r~|7paX!  
ifl LY7j  
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//获得文件长度 ^;{uop"DS  
public long getFileSize() Y#P!<Q>}  
{ P=P']\`p+  
int nFileLength = -1; =~,2E;#X  
try{ ES(qu]CjI  
URL url = new URL(siteInfoBean.getSSiteURL()); pL*aU=FjQ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Wj)v,v2&  
httpConnection.setRequestProperty("User-Agent","NetFox"); RP 6<#tq,  
19[.&-u"  
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int responseCode=httpConnection.getResponseCode(); C!1)3w|  
if(responseCode>=400) 5|}u25J  
{ +~==qLsU  
processErrorCode(responseCode); b'4}=Xpn  
return -2; //-2 represent access is error trA ^JY  
} l"h6e$dP  
/,<s9 :  
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String sHeader; Ai:,cY5%  
,l,q;]C%  
I4<_y5  
for(int i=1;;i++) ZBH^
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{ x*X{*?5@  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 8X? EB6=c  
//Utility.log(in.readLine()); ~XXNzz]?  
sHeader=httpConnection.getHeaderFieldKey(i); oOLj? 0t  
if(sHeader!=null) [T3%Xt'4  
{ 4B[uF/[  
if(sHeader.equals("Content-Length")) #N"QTD|i  
{ mYk~ ]a-  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); |~v2~   
break; LF
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} m}beT
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} ^mut-@ N9  
else !F Zg' 9  
break; C0^r]^$Z  
} R%9,.g<  
} w%oa={x  
catch(IOException e){e.printStackTrace ();} nb*`GE  
catch(Exception e){e.printStackTrace ();} 7pyaHe  
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Utility.log(nFileLength); 3/c%4b.Z  
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*
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return nFileLength; NE &{_i!  
} IO2@^jup  
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//保存下载信息（文件指针位置） m*lcIa  
private void write_nPos() yI-EF)A@;  
{ oykb8~u}}  
try{ F0kAQgUv  
output = new DataOutputStream(new FileOutputStream(tmpFile)); W]>%*n  
output.writeInt(nStartPos.length); iJKGzHvS  
for(int i=0;i<nStartPos.length;i++) UQP>yuSx  
{ fL-$wK<p<  
// output.writeLong(nPos); Vhe$vH  
output.writeLong(fileSplitterFetch.nStartPos); u3Zu ~C  
output.writeLong(fileSplitterFetch.nEndPos); X<v1ES$  
} _1YC9}  
output.close(); =?\%E[j  
} `Hu2a]e9  
catch(IOException e){e.printStackTrace ();} u2[L^]|  
catch(Exception e){e.printStackTrace ();} d+ [2Sm(7  
} ZC^NhgX  
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m  
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//读取保存的下载信息（文件指针位置） e)XnS'  
private void read_nPos() iG=Di)O  
{ }{&;\^i  
try{ CHCT e  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); [;~"ctf{  
int nCount = input.readInt(); nuA 0%K  
nStartPos = new long[nCount]; F]0 qt$GO  
nEndPos = new long[nCount]; o?IrDQ2gmh  
for(int i=0;i<nStartPos.length;i++) Czy}~;_Ay  
{ E},zB*5TH  
nStartPos = input.readLong(); ]9W7]$  
nEndPos = input.readLong(); 5e?<x>e  
} tCwB7c-  
input.close(); 7y.iXe!P  
} ao
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catch(IOException e){e.printStackTrace ();} e3[Q6d&|  
catch(Exception e){e.printStackTrace ();} {/,AMJ<:G]  
} _~F 0i?  
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private void processErrorCode(int nErrorCode) -]n%+,3L  
{ y(^\]-fE  
System.err.println("Error Code : " + nErrorCode); .t&G^i'n  
} Zzb?Nbf  
bUYjmb2g)  
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//停止文件下载 YJ~
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public void siteStop() O*W<za;  
{ U9 mK^  
bStop = true; 0f'LXn  
for(int i=0;i<nStartPos.length;i++) 5
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fileSplitterFetch.splitterStop(); ":GC}VIS  
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} YPCitGBl  
} (S?DKPnR  
//负责部分文件的抓取 uotW[L9  
**FileSplitterFetch.java }-u%6KZ   
*/ ~sq@^<M)s  
package NetFox; ?a1pO#{Dg  
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+!$`0v
  
import java.io.*; }WBHuVcZG  
import java.net.*; q1ZZ T"'  
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public class FileSplitterFetch extends Thread { $~
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String sURL; //File URL !aL=R)G&e  
long nStartPos; //File Snippet Start Position ~CdW:t  
long nEndPos; //File Snippet End Position 4:/^.:  
int nThreadID; //Thread's ID - leYR`P  
boolean bDownOver = false; //Downing is over |f.,fVVV;  
boolean bStop = false; //Stop identical Q7tvpU  
FileAccessI fileAccessI = null; //File Access interface 6GqC]rd*:  
/{W6]6^  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 3=*ur( Qy  
{ N0JdU4'  
this.sURL = sURL; eg1F[~YL/  
this.nStartPos = nStart; ,(f W0d#  
this.nEndPos = nEnd; -8<vWe  
nThreadID = id; @~UQU)-(  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ;P/ 4.|<  
} GS}JyU  
9jM7z/Ff  
@7V~CNB+  
public void run() 8B5WbS fL^  
{ a#& ( i  
while(nStartPos < nEndPos && !bStop) MX.?tN#F|H  
{ D_)/.m  
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;y50t$0  
try{ evNe6J3  
URL url = new URL(sURL); ]]3rSXs2}J  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); j]vEo~Bbh  
httpConnection.setRequestProperty("User-Agent","NetFox"); Nd{U|k3pL  
String sProperty = "bytes="+nStartPos+"-"; j2.7b1s  
httpConnection.setRequestProperty("RANGE",sProperty); S kB*w'k  
Utility.log(sProperty); yf4L0.  
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InputStream input = httpConnection.getInputStream(); /SQ/$`1{  
//logResponseHead(httpConnection); KC9e{  
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byte[] b = new byte[1024]; .aVtd [  
int nRead; 3dolrW  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Jyr V2Tk^  
{ .`V$j.a  
nStartPos += fileAccessI.write(b,0,nRead); %H2ios[UO  
//if(nThreadID == 1) o P;6i  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ,VSO;:Z  
} c"pOi&  
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9cU9'r# h  
Utility.log("Thread " + nThreadID + " is over!"); x{tlC}t  
bDownOver = true; \<09.q<8  
//nPos = fileAccessI.write (b,0,nRead); `Pc<0*`a  
} !6@'H4cb=  
catch(Exception e){e.printStackTrace ();} bovAFdHW  
} L[,19;(  
} u]9\_{c]Q  
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//打印回应的头信息 22U`1AD3U  
public void logResponseHead(HttpURLConnection con) S6a\KtVa  
{ (Cfb8\~  
for(int i=1;;i++) QCE7VV1Rw  
{ PLMC<4$s  
String header=con.getHeaderFieldKey(i); Ki7t?4YE  
if(header!=null) ,sL%Ykr  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ws^Ne30R  
Utility.log(header+" : "+con.getHeaderField(header)); 6)P.wW  
else CH 29kQ  
break; NY.*
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} ~(kqq#=s  
} ( N};.DB1Y  
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public void splitterStop()  X0$q!  
{ v+W'0ymbnV  
bStop = true; N'R^gL  
} +*?l">?|F  
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} GZNN2 '  
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/* 0<NS1y  
**FileAccess.java v$Hz)J.01  
*//文件访问(定位，写) zyUS$g]&  
package NetFox; MGt>:&s(]  
import java.io.*; # #2'QNN  
QuPz'Ut#  
/lu|FWbEw  
public class FileAccessI implements Serializable{ %Uz\P|6PO  
b/]4#?g  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 jy?*`q1]  
RandomAccessFile oSavedFile;
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long nPos; }^ ,D~b-nB  
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public FileAccessI() throws IOException n$r`s`}  
{
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this("",0); >RAg63!`  
} 4n7Kz_!SVf  
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public FileAccessI(String sName,long nPos) throws IOException 9Ffam#  
{ s(3HZ>qx;  
oSavedFile = new RandomAccessFile(sName,"rw"); H@?} !@  
this.nPos = nPos; 'ET];iZ2  
oSavedFile.seek(nPos); o,dp{+({  
} jYRSV7d  
V3q`V/\  
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public synchronized int write(byte[] b,int nStart,int nLen) e&d$kUJrq  
{ \GxqE8  
int n = -1; #]tDxZ] 6  
try{ Hy&Z0W'
l  
oSavedFile.write(b,nStart,nLen); @:GqOTN  
n = nLen; x]x3iFD  
} L'?aoRj  
catch(IOException e) M-Efe_VRQc  
{ `cXLa=B)9  
e.printStackTrace (); >RkaFcq  
} 8X"4RyNSn  
cOX)+53  
wTU$jd1;+  
return n; w|s2f`!  
} ]B=*p0~j^n  
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*  
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} \2 N;VE  
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/* eTvjo(Lvx  
**SiteInfoBean.java vu\W5M  
*/ 'kt6%d2  
package NetFox; @Xl(A]w%!  
s.i9&1Y-!  
f/UU{vX(  
public class SiteInfoBean { nLz;L r!  
WX?nq'nr  
8^y=YUT  
private String sSiteURL; //Site's URL s_IFl5D]  
private String sFilePath; //Saved File's Path %"A8Af**I  
private String sFileName; //Saved File's Name >,]a>V  
private int nSplitter; //Count of Splited Downloading File N wk  
r*vh3.Agl  
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public SiteInfoBean() 9u{[e"  
{//nSplitter的缺省值为5 &'W7-Z\j-  
//default value of nSplitter is 5 ?j.a>{  
this("","","",5); Q!@M/@-Ky  
} |ffHOef  
K?'m#}]  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) zMbFh_dcq  
{ 18rV Acj  
sSiteURL= sURL; E0
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sFilePath = sPath; sT2`y$'  
sFileName = sName; =f!A o:Uc  
this.nSplitter = nSpiltter; RxYENG]/6  
%QEBY>|lI  
>ceC8"}J5M  
} N'ER!=l)  
l+"p$iZs  
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public String getSSiteURL() @u9L+*F  
{ ?5n
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return sSiteURL; [S,$E6&j$"  
} |w|c!;,  
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aj;x:UqpJ  
public void setSSiteURL(String value) oLKliA=q  
{ M^:JhX{  
sSiteURL = value; B.5+!z&7  
} e3SnC:OWf  
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public String getSFilePath() zU&Iy_Ke.  
{ qSr]d`7@  
return sFilePath; giNXXjl  
} J\*uW|=F  
_F6<ba}o3  
/e>%yq<9B  
public void setSFilePath(String value) D=z~]a31!  
{ -\f7qRW^U  
sFilePath = value; #17 &rizl  
} :VlA2Ih&q  
iRsB|7v[,  
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public String getSFileName() jSE)&K4nI  
{ $lT8M-yK\  
return sFileName; gdf0  
} gxVr1DIkN  
$uTrM8  
q1:dcxR[  
public void setSFileName(String value) K^fs#7  
{ hO8xH +;  
sFileName = value; _S ng55s  
} =fRS UtX  
\HLo%]A@M  
r 1r@TG\  
public int getNSplitter() h^=;
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{ Ak@!F6~  
return nSplitter; zJw5+ +  
} pmB {b  
0(-4"u>?  
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public void setNSplitter(int nCount) 8C*@d_=q  
{ WBWW7
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nSplitter = nCount; &B(z**+9  
} " 7^nRJy  
} p\=T#lb  
uG7]s]Wdz;  
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/* <K^a2 D  
**Utility.java ' J@J$#6  
*/ >(a35 b$  
package NetFox; n3~axRPO  
#b;?:.m\=  
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public class Utility { h-ii-c?R@0  
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public Utility() 4aOz=/x2  
{ !2!Zhw2u  
5]dlD #  
@lj|  
} `qhT  
<h:xZtz  
//线程睡眠 nvrh7l9nX  
public static void sleep(int nSecond) ^.LB(GZ,  
{ 95'+8*YCY  
try{ {`SMxDevc}  
Thread.sleep(nSecond); kMVr[q,MEq  
} O`y3H lc  
catch(Exception e) GLO3v. n;  
{ -b^dK)wR~  
e.printStackTrace (); >} 2C,8N  
} ys=} V|  
} D?_K5a&v,  
Qg/FFn^Kg*  
//日志 l0,VN,$Yl  
public static void log(String sMsg) y5eEEG6  
{ B%\&Q@X  
System.err.println(sMsg); _\\Al v.  
} ]\^O(BzB  
{BJ>x:2  
ir}z^+  
public static void log(int sMsg)
_ VuWo  
{ &qg6^&  
System.err.println(sMsg); yx|iZhK0:}  
} y-E'Y=j  
} QO =5Q  
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:L@;.s  
/* ~o_JZ:  
**TestMethod.java *S*49Hq7c  
*/ zk{d*gN  
package NetFox; "e"#k}z9  
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public class TestMethod { PyfWIU7O  

=OFhM7  
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public TestMethod() 4\-11!'08  
{ ///xx/weblogic60b2_win.exe f\oW<2k]~  
try{ mce qZv  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); W|8VE,"7  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Q8`V0E\~  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 7vZO;FGtG  
fileFetch.start(); F6sQeU  
} y\_+,G0  
catch(Exception e){e.printStackTrace ();} FcM)v"bF&]  
1?&|V1
vc  
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} ;&=jSgr8  
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public static void main(String[] args) !+3&%vQ)  
{ U3&GRY|##  
new TestMethod(); 3;L$&X2  
} d\>XfS  
} -& (iU
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