http断点续传简单实现（java)

/* gi8FHSU|G  
**SiteFileFetch.java _t$sgz&  
*/ txpgO1  
package NetFox; K'bP@y_cq  
import java.io.*; Z;i:](  
import java.net.*; Dv"9qk  
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public class SiteFileFetch extends Thread { 45e~6",  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Y73C5.dNcE  
long[] nStartPos; //开始位置 :h$$J lP  
long[] nEndPos; //结束位置 _w{Qtj~s|  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 s1rCpzK0  
long nFileLength; //文件长度 pRqx`5 }  
boolean bFirst = true; //是否第一次取文件 ixFi{_  
boolean bStop = false; //停止标志 .8R@2c`}Cs  
File tmpFile; //文件下载的临时信息 m*pJBZxd  
DataOutputStream output; //输出到文件的输出流 NUZl`fu1Z4  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 2iOV/=+  
public SiteFileFetch(SiteInfoBean bean) throws IOException YVU7wW,1  
{ 3Ul*QN{6  
siteInfoBean = bean; S!UaH>Rh  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 3<!7>]A  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); M7T5 ~/4  
if(tmpFile.exists ()) Ey2^?  
{ 'V
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bFirst = false; QY/w  
read_nPos(); zdYjF|  
} r" y.KD^  
else 2:kH[#  
{ Ie_wHcM<  
nStartPos = new long[bean.getNSplitter()]; +R&gqja  
nEndPos = new long[bean.getNSplitter()]; NJ<F>3  
} Q?vlfZR`8  
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} D^O@'zP=At  
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public void run() gJXaPJA{  
{ }OUtsh]y  
//获得文件长度 AKC`TA*E  
//分割文件 tA;}h7/Lc~  
//实例FileSplitterFetch 8=l%5r^cq  
//启动FileSplitterFetch线程 YWLj?+  
//等待子线程返回 wp_0+$?s  
try{ Upe%r
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if(bFirst) M >u_4AY  
{ QV!up^Zso  
nFileLength = getFileSize(); 2ESo2  
if(nFileLength == -1) >A= f1DF  
{ r;{.%s7  
System.err.println("File Length is not known!"); RP"kC4~1  
} aOp\91  
else if(nFileLength == -2) wT@og|M  
{ icgfB-1|i  
System.err.println("File is not access!"); b9krOe*j  
} S'" Df5  
else 6Oq7#3]  
{ &ncvGDGi  
for(int i=0;i<nStartPos.length;i++) AH^/V}9H  
{ w<#!h6Y=  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); +[VXs~I q  
} Psf#c:*_)  
for(int i=0;i<nEndPos.length-1;i++) kmW4:EA%  
{ Y4-t7UlS;  
nEndPos = nStartPos[i+1]; J5
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} vaLSH xi  
nEndPos[nEndPos.length-1] = nFileLength; *w&e\i|7  
} x:Y1P:  
} G\i
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//启动子线程 ZVBXx\{s  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; KO [Yi  
for(int i=0;i<nStartPos.length;i++) ]gOy(\B  
{ COlqcq'qAu  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), *@5@,=d  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 9;{CIMg&  
nStartPos,nEndPos,i); as|<}:V  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1zv'.uu.,  
fileSplitterFetch.start(); :;}P*T*PU  
} $FVNCFN%  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ]^E?;1$f?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); la!~\wpa  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", :TbgFQ86~  
nEndPos = " + nFileLength); }vuO$j  
// fileSplitterFetch[nPos.length-1].start(); CJY$G}rk  
FrS]|=LJhX  
U
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//等待子线程结束 tmqOJ  
//int count = 0; ?s01@f#  
//是否结束while循环 [,Gg^*umS  
boolean breakWhile = false; `yyG/l  
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while(!bStop) [0!(xp^  
{ .('SW\u-  
write_nPos(); Z@HEj_n  
Utility.sleep(500); ftb\0,-  
breakWhile = true; j#|ZP-=1_  
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for(int i=0;i<nStartPos.length;i++) @d'j zs  
{ H_a[)DT  
if(!fileSplitterFetch.bDownOver) VA%J\T|G2\  
{ I7onX,U+  
breakWhile = false; ="+#W6bZT  
break; z/-=%g >HA  
} ?,z}%p  
} $Sq:q0  
if(breakWhile) )lkjqFQ(  
break; `Di{}/2  
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//count++; BmT!aue  
//if(count>4) i!Ba]n   
// siteStop(); Gc?a+T  
} /~1+i'7V.,  
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System.err.println("文件下载结束！"); dtDFoETz  
} /ZX}Nc g  
catch(Exception e){e.printStackTrace ();} 6ujWNf  
} .-zom~N-?  
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//获得文件长度 F9^S"qv$  
public long getFileSize() 203s^K61  
{  mh%VrAq  
int nFileLength = -1; z{q`GwW  
try{ ).O)p9  
URL url = new URL(siteInfoBean.getSSiteURL()); KNl$3
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); inL(X;@yo  
httpConnection.setRequestProperty("User-Agent","NetFox"); W?&%x(6M  
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int responseCode=httpConnection.getResponseCode(); >P(.:_^p  
if(responseCode>=400) Uo49*Mr  
{ ?,/ }`3Vw  
processErrorCode(responseCode); h[ ZN+M  
return -2; //-2 represent access is error kJU2C=m@e2  
}  " bG2:  
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String sHeader; +@UV?"d  
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for(int i=1;;i++) hH.G#-JO  
{ ~*7]r`6\@  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); GgU/!@  
//Utility.log(in.readLine()); SbZ6t$"  
sHeader=httpConnection.getHeaderFieldKey(i); [g,}gyeS(  
if(sHeader!=null) \V:^h[ad  
{ z?zL97H  
if(sHeader.equals("Content-Length")) +ZYn? #IQ  
{ !D6]J
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); !-bB559Nv  
break; 2wn2.\v M  
} KvSG;  
} 4i bc  
else buC{r,  
break; $b\P|#A  
} x-c"%Z|  
} bt *k.=p  
catch(IOException e){e.printStackTrace ();} =1! 'QUc  
catch(Exception e){e.printStackTrace ();} _F{C\}  
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Utility.log(nFileLength); PF2nLb2-  
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return nFileLength; u2I Cl  
} BUFv|z+H  
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& kIFcd@  
//保存下载信息（文件指针位置） }u|q0>^8  
private void write_nPos() $]1=\I  
{ ^Cmyx
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try{ $>gFf}#C  
output = new DataOutputStream(new FileOutputStream(tmpFile)); H]s.=.Ki  
output.writeInt(nStartPos.length); 6@o*xK7L  
for(int i=0;i<nStartPos.length;i++) POW>~Tof1  
{ QJNFA}*>  
// output.writeLong(nPos); mOSv9w#,  
output.writeLong(fileSplitterFetch.nStartPos); 4Hg9N}  
output.writeLong(fileSplitterFetch.nEndPos); X]=t>
 
} ;<5q]/IHK  
output.close(); `/g UV  
} [lAp62i5  
catch(IOException e){e.printStackTrace ();} m|# y >4  
catch(Exception e){e.printStackTrace ();} NI5``BwpO  
} jpOp
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//读取保存的下载信息（文件指针位置） l%ZhA=TKQ  
private void read_nPos() =sFTxd_"iQ  
{
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try{ wBzC5T%,  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ]9L oZ)  
int nCount = input.readInt(); fVwUe _Y  
nStartPos = new long[nCount]; Q\)F;:|  
nEndPos = new long[nCount]; 'yth'[  
for(int i=0;i<nStartPos.length;i++) *"kM{*3:v  
{ .pq%?&  
nStartPos = input.readLong(); E4!Fupkpf  
nEndPos = input.readLong(); \jA~9  
} .543N<w  
input.close(); pp2~Meg  
} *
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catch(IOException e){e.printStackTrace ();} x"(KBEK~  
catch(Exception e){e.printStackTrace ();} edV\-H5<  
} +V+a4lU14  
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private void processErrorCode(int nErrorCode) {$r[5%L\H  
{ 5IN(|B0  
System.err.println("Error Code : " + nErrorCode); F?cK-.  
} }Lv;

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//停止文件下载 :4s1CC+@\  
public void siteStop() _
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{ 1}37Q&2  
bStop = true; M;NX:mX9  
for(int i=0;i<nStartPos.length;i++) 6RM/GM  
fileSplitterFetch.splitterStop(); Ie^l~G
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} $N\Ja*g  
} F"<vaqT2  
//负责部分文件的抓取 ccnK#fn v  
**FileSplitterFetch.java [Yyk0Qv|4  
*/ -+5>|N#  
package NetFox; Tr|JYLwF
 
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import java.io.*; 4=.so~9odX  
import java.net.*; ^&)|sP  
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!  
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public class FileSplitterFetch extends Thread { Bf:Q2slqI  
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String sURL; //File URL Q^I\cAIB  
long nStartPos; //File Snippet Start Position to\Ni~a&  
long nEndPos; //File Snippet End Position CJ%I51F`X  
int nThreadID; //Thread's ID o.\oA6P_  
boolean bDownOver = false; //Downing is over <1pEwI~  
boolean bStop = false; //Stop identical RL<c>PY  
FileAccessI fileAccessI = null; //File Access interface 5?L<N:;J_  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException xCKRxF  
{ WKU=.sY  
this.sURL = sURL; X(C$@N  
this.nStartPos = nStart; PzGWff!*n  
this.nEndPos = nEnd; d
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nThreadID = id; vI]N^j2%  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 dTtSUA|V7"  
} 2JFpZU"1  
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public void run() {e5= &A  
{ Tf)*4O4@'  
while(nStartPos < nEndPos && !bStop) fAmz4  
{ y==CTY@  
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try{ EzIGz[
 
URL url = new URL(sURL); "vGW2~*)  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); D-4f.Tq4#  
httpConnection.setRequestProperty("User-Agent","NetFox"); l(q ,<[O  
String sProperty = "bytes="+nStartPos+"-"; nOz.G"  
httpConnection.setRequestProperty("RANGE",sProperty); ;6wA"  
Utility.log(sProperty); 'QIqBU'~  
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InputStream input = httpConnection.getInputStream(); ]:f%l mEy  
//logResponseHead(httpConnection); \L\b$4$d  
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byte[] b = new byte[1024]; Wm3X[?V  
int nRead; 9,tej  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) km40qO@3  
{ XrPfotj1  
nStartPos += fileAccessI.write(b,0,nRead); }{"fJ3] c^  
//if(nThreadID == 1) 4e1Y/ Xq`  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _[y/Y\{I  
} '7@R7w!E4H  
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Utility.log("Thread " + nThreadID + " is over!"); wT\49DT"7  
bDownOver = true; j+(I"h3  
//nPos = fileAccessI.write (b,0,nRead); o lxByzTh>  
} <9%R\_@$H  
catch(Exception e){e.printStackTrace ();} g[t [/TV  
} BSMwdr  
} V_:&S2j  
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//打印回应的头信息 |W\(kb+  
public void logResponseHead(HttpURLConnection con) m9A
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{ Bw{I;rW{2  
for(int i=1;;i++) #=v~8  
{ 9M9?%N:ra  
String header=con.getHeaderFieldKey(i); ]cN1c}  
if(header!=null) ~=
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); F3N6{ysK#  
Utility.log(header+" : "+con.getHeaderField(header)); d:{O\   
else e!r-+.i(  
break; AvHCO8h|  
} =>dGL|  
} <rmvcim{*  
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public void splitterStop() _7)n(1h[3b  
{ ->{KVPHe{  
bStop = true; +H2-ZXr  
} 3Le{\}-$.  
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} M:6"H%h,W  
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/* TBrPf-Xr  
**FileAccess.java Fr$5RAyg  
*//文件访问(定位，写) 2wgg7[tGi  
package NetFox; pU7lnS[  
import java.io.*;  v<:R#  
O,A{3DAe0  
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public class FileAccessI implements Serializable{ /^
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 s|B3~Q]  
RandomAccessFile oSavedFile; &l[$*<P5V  
long nPos; =6#Eh=7N  
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2,P^n4~A?w  
public FileAccessI() throws IOException L z1ME(  
{ UOmY-\ &c  
this("",0); hDq`Z$_+KX  
} 0nD/;\OU  
tlt*fH$.  
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public FileAccessI(String sName,long nPos) throws IOException /Qk4  
{ kn"(A.R  
oSavedFile = new RandomAccessFile(sName,"rw"); mo#04;VF  
this.nPos = nPos; bD8Gwi=iiu  
oSavedFile.seek(nPos); 'oC) NpnH  
} _H=Uwi_g  
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}Ys>(w  
public synchronized int write(byte[] b,int nStart,int nLen) AZ}Xj>=  
{ Bng@-#`/  
int n = -1; yEj^=pw  
try{ ?8Cq{  
oSavedFile.write(b,nStart,nLen); k,F6Tx  
n = nLen; xpx\=iAe  
} A6iq[b]  
catch(IOException e) Nl(3Xqov  
{ 78H'ax9m  
e.printStackTrace (); yqiq,=OvP  
} qc~iQSI  
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?#YE`]  
return n; d6sye^P  
} {Fe[:\  
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} *%t^;&x?  
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/* 6;qy#\}2  
**SiteInfoBean.java r s?R:+  
*/ Ktm4 A O  
package NetFox; c#tjp(-  
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public class SiteInfoBean { :+|Z@KB  
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A4<Uu~  
private String sSiteURL; //Site's URL A;|D:;x3G  
private String sFilePath; //Saved File's Path %zw1}|s#z  
private String sFileName; //Saved File's Name >q1L2',pK  
private int nSplitter; //Count of Splited Downloading File -701j'q{  
GU8sO@S5#  
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public SiteInfoBean() @Sbe^x  
{//nSplitter的缺省值为5 *lw_=MXSK  
//default value of nSplitter is 5 <)-Sj,  
this("","","",5); ,47Y9Kz9  
} PJrtMAcKq  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ?r2` Q  
{ LRG6
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sSiteURL= sURL;
"s_lP&nq  
sFilePath = sPath; -JjM y X  
sFileName = sName; `&sH-d4v  
this.nSplitter = nSpiltter; E5lBdM>2  
/U)D5ot<  
 *m,k(/>  
} Nf"r4%M<6  
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public String getSSiteURL() ^ tg<K  
{
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return sSiteURL; %vhnl'  
} Z//+Gw<'  
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public void setSSiteURL(String value) ><$d$(  
{ in-HUG  
sSiteURL = value; )vb*Ef  
} > eIP.,9  
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public String getSFilePath() &&:YVd  
{ !~D}/Q;#}\  
return sFilePath; t*T2Z-!P  
} V<uR>TD(  
z]?N+NHOA  
l6 H|PR{  
public void setSFilePath(String value) \(Y\|zC'0$  
{ e`xdSi>E  
sFilePath = value; TS9|a{j3!  
} Yqi4&~?db  
&3Szje  
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public String getSFileName() cH?B[S
;]  
{ 5ZK@`jkE  
return sFileName; c~uKsU  
} 4f'V8|QM{  
Y+*0~xm4  
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public void setSFileName(String value) f;gw"onx8F  
{ T<p !5`B1  
sFileName = value; EYEnN  
} h+&OQ%e=8  
`FTy+8mw  
=mpVYA  
public int getNSplitter() v`zJb00DT  
{ W=vP]x >J  
return nSplitter; IrhA+)pdse  
} QPg8;O  
^ ALly2
  
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public void setNSplitter(int nCount) `_RTw5{  
{ -w_QJ_z_  
nSplitter = nCount; *b/`Ya4  
} E5xzy/ZQ  
} 1Z
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&6YIn|}  
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/* u!X|A`o5i  
**Utility.java qHrA%k^!2O  
*/ NzSoqh{R  
package NetFox; jWl)cC  
bc)~k:  
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public class Utility { L3--r  
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public Utility() +hT:2TXn  
{ ()+<)hg}2  
^,8)iV0j_  
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} QQ~-  
@&:ar
 
//线程睡眠 X{'q24\F  
public static void sleep(int nSecond) e<h~o!za  
{ K4;'/cS  
try{ I}6\Sv=  
Thread.sleep(nSecond); t&CJ%XP  
} gy0haW  
catch(Exception e) Vz)`nmO}5\  
{ 

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e.printStackTrace (); 3`.7
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} 2.zsCu4lj.  
} +W\f(/q0  
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//日志 s
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public static void log(String sMsg) x`mN U  
{ muZ~*kMc  
System.err.println(sMsg); 9Hu/u=vB<  
} JS
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"4H +!r}  
public static void log(int sMsg) ^Z#W_R\l  
{ mfo1+owT  
System.err.println(sMsg); y_IM@)1H~  
} ;@Z#b8aM}  
} f[~L?B;_L  
;)e2@'Agl  
D-(w_$#  
/* 3G~@H>j  
**TestMethod.java Z1Z1@2 T
 
*/ (%xwl  
package NetFox; Mo @C9Y0  
K7W6ZH9;  
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public class TestMethod { @reeO=  
C@W"yYt  

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public TestMethod() ICkp$u^  
{ ///xx/weblogic60b2_win.exe 0B@Jity#!  
try{ p2udm!)J  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); <5jzl  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); )>-ibf`#?  
SiteFileFetch fileFetch = new SiteFileFetch(bean); K7Wk6Aw  
fileFetch.start(); iN0nw
]_*  
} "D=P8X&vs  
catch(Exception e){e.printStackTrace ();} `poE6\  
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} !0C^TCuG  
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.?e\I`Kk^'  
public static void main(String[] args) xz{IH,?IG  
{ )Ocl=H|=  
new TestMethod(); Gz[fG  
} G\Ro}5TO  
} Bw6
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