http断点续传简单实现（java)

/* tgn_\-+  
**SiteFileFetch.java +@),
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*/ ;EZ$8|  
package NetFox; iX0s4  
import java.io.*; : E`N0UA  
import java.net.*; "V!y"yQ  
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public class SiteFileFetch extends Thread { q.6$-w  
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SiteInfoBean siteInfoBean = null; //文件信息Bean VkCv`E  
long[] nStartPos; //开始位置 TY[{)aH{S  
long[] nEndPos; //结束位置 &KC^Vn3Nj  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 6 <JiHVP7  
long nFileLength; //文件长度 *i#m5f}  
boolean bFirst = true; //是否第一次取文件 \M>}-j`v  
boolean bStop = false; //停止标志 3-4' x2   
File tmpFile; //文件下载的临时信息 o:u *E  
DataOutputStream output; //输出到文件的输出流 :Hdn&a i  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Wu]Dpe  
public SiteFileFetch(SiteInfoBean bean) throws IOException b&s"/Y89  
{ Vt-D8J\A 0  
siteInfoBean = bean; #Jt9U1WbF  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); "' g*_  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); e*w2u<HP  
if(tmpFile.exists ()) au'Zjj/Ai5  
{ ?9#}p  
bFirst = false; 1*aw~nY
0  
read_nPos(); FVOR~z  
} c?;~Z  
else }ie\-V  
{ zoYw[YP9  
nStartPos = new long[bean.getNSplitter()]; sqw^Hwy=!2  
nEndPos = new long[bean.getNSplitter()]; 5\Sm^t|Tx  
} yrO\\No#H  
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} %;+Q
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public void run() 7Pu.<b}  
{ r=
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//获得文件长度 p`ai2`qC`  
//分割文件 J{"<Hgb  
//实例FileSplitterFetch )N!-g47o%#  
//启动FileSplitterFetch线程 ]Z?$ 5Ks  
//等待子线程返回 ~3bn?'`  
try{ Jsf-t  
if(bFirst) :e1BQj`R  
{ $CXKeWS=Q.  
nFileLength = getFileSize(); uY+N163i  
if(nFileLength == -1) NMYkEz(&R  
{ N0EJHS,>e  
System.err.println("File Length is not known!"); C.M
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} s,UccA@  
else if(nFileLength == -2) cTf/B=yMi  
{ 6|*em4  
System.err.println("File is not access!"); J0@ ^h  
} yZJR7+  
else wmh[yYWc  
{
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for(int i=0;i<nStartPos.length;i++) '(M8D5?N-  
{ / 0Z_$Q&e  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); bM`7>3 d7E  
} |,k,X}gP  
for(int i=0;i<nEndPos.length-1;i++) ?0HPd5=<v  
{ 0KknsP7  
nEndPos = nStartPos[i+1]; W#1t%hT$  
} n~xh %r;  
nEndPos[nEndPos.length-1] = nFileLength; dQ+{
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}
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} }{<@wE%s  
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KCG-&p$v@s  
//启动子线程 nJH+P!AC  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; k[3J5 4`g1  
for(int i=0;i<nStartPos.length;i++) f(Jz*el S  
{ z?V'1L1gM  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), \yeo-uN8  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 1RC(T{\x  
nStartPos,nEndPos,i); u'"VbW3u n  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); >W%tEc  
fileSplitterFetch.start(); #SiOx/  
} gKK*` L~  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )sg@HFhY'  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); j_2-  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", xf/ SUO F  
nEndPos = " + nFileLength); f{=0-%dA  
// fileSplitterFetch[nPos.length-1].start(); Z
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!o A,^4(  
//等待子线程结束 7I>@PVN  
//int count = 0; @ %LrpD  
//是否结束while循环 0_7A <   
boolean breakWhile = false;  h"<-^=b  
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G2Zr(b')  
while(!bStop) Ms8&$  
{ -ZXC^zt  
write_nPos(); x O`#a=  
Utility.sleep(500); w>M8FG(4]  
breakWhile = true; 'Q\I@s }  
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for(int i=0;i<nStartPos.length;i++) _G]f v'  
{ VFLxxFJ  
if(!fileSplitterFetch.bDownOver) \OMWE/qMy  
{ 83io@*D  
breakWhile = false; E:,V{&tLK  
break; NEInro<  
} 8RS=Xemds  
} XI#1)  
if(breakWhile) =m{]Xep   
break; P9j[ NEV  
8
.9TWsZ  
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//count++; 0Q]@T@F.  
//if(count>4) eq)8V x0  
// siteStop(); A|!u`^p  
} |> mx*G  
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System.err.println("文件下载结束！"); uh`W} n  
} cfn\De%.  
catch(Exception e){e.printStackTrace ();} rv/O^aL`Y  
} KrwG><
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;[ UGEi  
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//获得文件长度 }[a  
public long getFileSize() >cm*_26;I  
{ %J
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int nFileLength = -1; a#i;*J  
try{ ":t'}Eg=6  
URL url = new URL(siteInfoBean.getSSiteURL()); HFV4S]U=  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |L XYF$  
httpConnection.setRequestProperty("User-Agent","NetFox"); \-A=??@H  
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int responseCode=httpConnection.getResponseCode(); px!lJtvgo  
if(responseCode>=400) yHS=8!
  
{ tBS
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processErrorCode(responseCode);
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return -2; //-2 represent access is error k"-2OT  
} V-Ebi^gz5W  
# fvt:iE  
7]}n0*fe  
String sHeader; \nQV{J  
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{Vy2uow0  
for(int i=1;;i++) }cDw9;~D  
{ laVqI|0q  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); [v7)xV@c  
//Utility.log(in.readLine()); 5&}
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sHeader=httpConnection.getHeaderFieldKey(i); iwJeV J  
if(sHeader!=null) ^{L/) Xy5  
{ ".Lwq_  
if(sHeader.equals("Content-Length")) F/BB]gUB  
{ 5r#0/1ym!  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); EA@p]+P  
break; 7GN>o@t  
} O>
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} )TNAgTmqK  
else JO\F-xO  
break; 9b KK  
} obYXDj2  
} 2)O-EAn  
catch(IOException e){e.printStackTrace ();} pwq a/Yi  
catch(Exception e){e.printStackTrace ();} &PJ&XTR  
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Utility.log(nFileLength); "AH1)skB:  
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return nFileLength; 
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} 19.+"H  
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//保存下载信息（文件指针位置） v
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private void write_nPos() 6y;R1z b  
{ 
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try{ "P4#Q_  
output = new DataOutputStream(new FileOutputStream(tmpFile)); \UKr|[P
  
output.writeInt(nStartPos.length); Jzqv6A3G  
for(int i=0;i<nStartPos.length;i++) *AEN  
{ Cx
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// output.writeLong(nPos); 4~;x(e@S  
output.writeLong(fileSplitterFetch.nStartPos); @m*^v\q<u  
output.writeLong(fileSplitterFetch.nEndPos); J!l/!Z>!cF  
} }=)  
output.close(); zCOzBL/1q  
} p[kEFE,%  
catch(IOException e){e.printStackTrace ();} nP9zTa  
catch(Exception e){e.printStackTrace ();} ,MH9e!  
} 9 U6cM-p?  
1+P&O4>  

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//读取保存的下载信息（文件指针位置） nJEm&"AI  
private void read_nPos() Qfx:}zk{  
{ >Q159
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try{ ~N2<-~=si  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); _0Mt*]L }  
int nCount = input.readInt(); ^SdorPOq&  
nStartPos = new long[nCount]; ==$>M d  
nEndPos = new long[nCount]; Yh=/?&*  
for(int i=0;i<nStartPos.length;i++) tvh)N{j  
{ {5<3./5O  
nStartPos = input.readLong(); s,KE,$5F   
nEndPos = input.readLong(); x3dP`<   
} 9?4EM^-  
input.close(); Fu@2gd  
} V\C$/8v  
catch(IOException e){e.printStackTrace ();} Y!M&8;>  
catch(Exception e){e.printStackTrace ();} e!+_U C  
} HzdtR  
#;l~Y}7'  
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private void processErrorCode(int nErrorCode) /eZ UAxq  
{ N~<H`  
System.err.println("Error Code : " + nErrorCode); q-3,p.  
} Yv}V =O%  
pf_(?\oz>  
LV$@J  
//停止文件下载 zkFx2(Hq-f  
public void siteStop() 2m$\]\kCUv  
{ kZ8+ev=  
bStop = true; IaDN[:SX  
for(int i=0;i<nStartPos.length;i++) z%$,F9/  
fileSplitterFetch.splitterStop(); &f2'cR  
Z
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} (]wd8M  
} _z`g@[m:t  
//负责部分文件的抓取 JIw=Bs  
**FileSplitterFetch.java ,U-aZ  
*/ ;cye 'E  
package NetFox; v61'fQ1Qg!  
q6xm#Fd'.  
3_AVJv ;N  
import java.io.*; d&z^u.SY  
import java.net.*; DOk(5gR  
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public class FileSplitterFetch extends Thread { }]i re2j8  
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String sURL; //File URL STfcx]L  
long nStartPos; //File Snippet Start Position _{d0Nm  
long nEndPos; //File Snippet End Position r`t|}m  
int nThreadID; //Thread's ID x*p>l !  
boolean bDownOver = false; //Downing is over x)+3SdH  
boolean bStop = false; //Stop identical ]VarO'  
FileAccessI fileAccessI = null; //File Access interface 4 w$f-  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 1Wz -Z  
{ Rn"Raq7Cn*  
this.sURL = sURL; s]D&):  
this.nStartPos = nStart; -!p +^wC  
this.nEndPos = nEnd; nPAVrDg O  
nThreadID = id; g~>g])  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 DU@ZLk3  
} %Ls5:Z=  
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public void run() 
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{ 1WArgR  
while(nStartPos < nEndPos && !bStop) H%}ro.u  
{ e:&+m`OSH  
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try{ m1](f[$  
URL url = new URL(sURL); st|;]q9?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); nUgZ]ag=G  
httpConnection.setRequestProperty("User-Agent","NetFox"); 9>@@W#TK~  
String sProperty = "bytes="+nStartPos+"-"; ZmJ!ZKKch  
httpConnection.setRequestProperty("RANGE",sProperty); _8-iO.T+2  
Utility.log(sProperty); (W=J3?hn  
\]@XY_21  

UUE:>[,  
InputStream input = httpConnection.getInputStream(); c^4^z"Mo`  
//logResponseHead(httpConnection); ,wyfMOGLt  
X {["4  
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byte[] b = new byte[1024]; F|rJ{=x  
int nRead; ;q8tOvQ  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) R{GT? wl  
{ f3g#(1  
nStartPos += fileAccessI.write(b,0,nRead); uQ}0hs  
//if(nThreadID == 1) `oDs]90  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); %[l*:05  
} \R m2c8Z2  
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R<5GG|(B  
Utility.log("Thread " + nThreadID + " is over!"); zOkIPv52~  
bDownOver = true; H[cHF  
//nPos = fileAccessI.write (b,0,nRead);  D8w:c6b  
} u$3wdZ2&m  
catch(Exception e){e.printStackTrace ();} 6m=FWw3y  
} 6:(R/9!P  
} \[nvdvJv  
NXJyRAJ*%  
G>3]A5  
//打印回应的头信息 p1-bq:  
public void logResponseHead(HttpURLConnection con)  AU3Ou5  
{ $& 0hpg  
for(int i=1;;i++) vf|lF9@U  
{ } Fw/WD  
String header=con.getHeaderFieldKey(i); gK`o;` ^  
if(header!=null) nb -Je+  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); /Ir|& <yB  
Utility.log(header+" : "+con.getHeaderField(header)); ,>:   
else BW`)q/  
break; (|{bZ
W}  
} '1$#onx  
} C4#EN}  
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#P)7b,3pe  
public void splitterStop() gwf*M3(  
{ 1X5*V!u  
bStop = true; l> Mth+,b  
} (Wj2%*NT  
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} nJdO~0}3
 
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/* sRM3G]nUr  
**FileAccess.java ?|&plf|  
*//文件访问(定位，写) \Y EV 5  
package NetFox; \z/_vzz4  
import java.io.*; 34@f(^d+^  
bZ/4O*B  
ylV.ZoY6  
public class FileAccessI implements Serializable{ O_f+#K)  
oX2J2O  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 CdTyUl  
RandomAccessFile oSavedFile; Kb<^Wdy4T  
long nPos; uSAb  
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public FileAccessI() throws IOException
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{ 6X@]<R  
this("",0); R^
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} )2U#<v^
 
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public FileAccessI(String sName,long nPos) throws IOException NXwlRMbo  
{ QO'=O}e  
oSavedFile = new RandomAccessFile(sName,"rw"); |bHId!d  
this.nPos = nPos; v4:g*MD?~  
oSavedFile.seek(nPos); Ww{|:>j  
} !PaDq+fB  
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:+Pl~X"
_  
public synchronized int write(byte[] b,int nStart,int nLen) :6^8Q,C1@  
{ hhS]wM?B  
int n = -1; \F|L y >g  
try{ AYC22(  
oSavedFile.write(b,nStart,nLen);  Tl.%7)  
n = nLen; 'O\me  
} R*C  
catch(IOException e) xaiA?  
{ [vIHYp  
e.printStackTrace (); g{`rWKj  
} Jb~nu  
m[@7!.0=  
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return n; UE3#(:xA  
} Dn[iA~  
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} {kLL&`ii  
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/* w% Ug9  
**SiteInfoBean.java g@&@]63  
*/ ;'o:1{Y  
package NetFox; \XG18V&  
%H-(-v^T*  
#-QQ_  
public class SiteInfoBean { bS0z\!1  
(I?CW~3#  
b,?@_*qv+  
private String sSiteURL; //Site's URL hB
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private String sFilePath; //Saved File's Path Lv;R8^n  
private String sFileName; //Saved File's Name ` "Gd/  
private int nSplitter; //Count of Splited Downloading File
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public SiteInfoBean() SI:+I4i  
{//nSplitter的缺省值为5 {y{&tzZ  
//default value of nSplitter is 5 . Q#X'j  
this("","","",5); #+1*g4m~B  
} ]LvpYRU$P  
[*-DtbEk  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) +["t@Q4IQ  
{ &{s`=IeN  
sSiteURL= sURL; N XwQvm;q  
sFilePath = sPath; GC{)3)_ t  
sFileName = sName; 0]v:I
x  
this.nSplitter = nSpiltter; erG;M!9\  
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} w$JG:y#  
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public String getSSiteURL() W_zv"c  
{ FW)G5^Tf  
return sSiteURL; 49o5"M(  
} Kn]c4h}@b5  
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public void setSSiteURL(String value) ?i.]|#{Z  
{ p,y(Fc~]g'  
sSiteURL = value; R<}Yf[TQ  
} |%F[.9Dp  
U]!
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public String getSFilePath() 8:j8>K*6  
{ C|kZT<,]  
return sFilePath; MIcF"fB![  
} e1e2W
k  
wv 7jES  
3>[_2}l  
public void setSFilePath(String value) Z4\$h1tl  
{ v{ F/Bifo  
sFilePath = value; :)GtPTD  
} \W<r`t4v  
+LwE=unS  
:y)'_p *l/  
public String getSFileName() <y+8\m  
{ S[o_
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return sFileName; q?x.P2  
} *QzoBpO<  
i,=CnZCh  
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public void setSFileName(String value) zOR  
{ <r*A(}Y  
sFileName = value; 33O@jbs@  
} /aepE~T  
l<7)uO^8  
tUXq!r<'dT  
public int getNSplitter() 3|/<
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{ 'F'v/G~
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return nSplitter; ';buS -|6  
} W/PZD (  
sR`WV6!9  
Qh)QdW4  
public void setNSplitter(int nCount) .bh>_ W_h  
{ +tz^ &(  
nSplitter = nCount; 0&1!9-(d  
} lNSB "S  
} hP4*S^l  
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/* tA+ c  
**Utility.java mZVYgJQ[  
*/ }.<%46_Z-  
package NetFox; ]KMOLe6(  
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public class Utility { 56Q9RU(M  
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JF
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public Utility() NGHzifaE   
{ (,<
ti):  
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} F`9;s@V*  
M2ig iR  
//线程睡眠 i"uAT$xe  
public static void sleep(int nSecond) !$'s?rnh  
{ j|f$:j  
try{ CB5 ~!nKv&  
Thread.sleep(nSecond); 4'pg>;*.  
} RHo|&.B;+  
catch(Exception e) K[ZgT$zZ  
{ iVM{ L  
e.printStackTrace (); oI9Jp`  
} 4C&L%A  
} ]9?_m@Ihx  
U!sv6=(y@  
//日志 1]r+$L3  
public static void log(String sMsg) irNGURLm  
{ s}Q%]W  
System.err.println(sMsg); dKcHj<'E/  
} p1 tfN$-  
^a@Vn\V1  
X*Mw0;+T  
public static void log(int sMsg) v>TI.;{y  
{ WP1>)  
System.err.println(sMsg); 8phcekh+  
} P%5h!Z2m  
} w$*t.Q*  
=R)9_D6I  
y 1fl=i  
/* zV {[0s  
**TestMethod.java &UG7 g  
*/ O?omL5  
package NetFox; ~:."BA  
=4 &/Pr  
h3.wR]ut  
public class TestMethod { P)~PrTa%  
jp2AU,Cl  
94L P )n  
public TestMethod() {\G4YQ  
{ ///xx/weblogic60b2_win.exe `Nnqdc2  
try{ Pg%O
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); $l}MB7
 
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); %p?u ^rq  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ='=\!md  
fileFetch.start(); 2~+Iu+  
} ?6@Y"5 z3g  
catch(Exception e){e.printStackTrace ();} e[}R1/!L  
w/s{{X<bF  
Qz;2RELz  
} >l
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v/f&rK*>  
d[z+/L  
public static void main(String[] args) T"-HBwl  
{ _Tyj4t0ElV  
new TestMethod(); 8"+Re [  
} M?5[#0"&V  
} c$ Kn.<a  
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