http断点续传简单实现（java)

/* DJ
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**SiteFileFetch.java I&m' a  
*/ G$2@N6  
package NetFox; Oxa8ue?  
import java.io.*; .cHkh^EDY  
import java.net.*; Oi zj|'  
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public class SiteFileFetch extends Thread { hNhEA $X5  
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SiteInfoBean siteInfoBean = null; //文件信息Bean UhrRB  
long[] nStartPos; //开始位置 m"'}{3$%  
long[] nEndPos; //结束位置 \A,zwdt P  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 8\^A;5  
long nFileLength; //文件长度 !^ad{#|X  
boolean bFirst = true; //是否第一次取文件 7BL)FJ]UR]  
boolean bStop = false; //停止标志 ' ,S}X\  
File tmpFile; //文件下载的临时信息 SZyORN  
DataOutputStream output; //输出到文件的输出流 N#ZWW6  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） $d
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public SiteFileFetch(SiteInfoBean bean) throws IOException -jy0Kl/p  
{ T=)qD2?  
siteInfoBean = bean; !\[JWN@v  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); d,?Tq  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); KPI96P  
if(tmpFile.exists ()) 3h:y[Vm#9y  
{ gnjhy1o  
bFirst = false; N'WC!K.e
 
read_nPos(); J{.UUw9Agd  
} \1LfDlQk)  
else o<%0|n_O&  
{ ^!d0abA  
nStartPos = new long[bean.getNSplitter()]; S1I.l">P  
nEndPos = new long[bean.getNSplitter()]; mLpM8~L  
} m./PRV1$x  
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} ck<R
  
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} M;,$
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public void run() D[#V  
{ Y)DX   
//获得文件长度 =u?aP}zc  
//分割文件 o.Rv<a5.L  
//实例FileSplitterFetch YcX\t6VK  
//启动FileSplitterFetch线程 ($kw*H{Ah^  
//等待子线程返回  u\L}B!  
try{ pm,xGo2  
if(bFirst) 
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{ ~bxev/$d  
nFileLength = getFileSize(); (nt`8 0  
if(nFileLength == -1) |Ia9bg'1U  
{ Uu5(/vw]  
System.err.println("File Length is not known!"); gWGDm~+  
} M@{#yEP  
else if(nFileLength == -2) sqtz^K ROM  
{ #$-E5R;x  
System.err.println("File is not access!"); 3g;,  
} ESIP+  
else rO$pj~!|Q  
{ 5EcVW|(  
for(int i=0;i<nStartPos.length;i++) fDf[:A,8  
{ .Mb[j1L^  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); dY S(}U  
} , :#bo]3  
for(int i=0;i<nEndPos.length-1;i++)
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{ JEp)8{.bW8  
nEndPos = nStartPos[i+1]; %7)TiT4V
 
} > 0MP[  
nEndPos[nEndPos.length-1] = nFileLength; 8YQuq.(>a  
} [3G{NC|'  
} I[Lg0H8  
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bGH#s {'5  
//启动子线程 }q.D)'g_  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; FnA Kfh(  
for(int i=0;i<nStartPos.length;i++) X3l>GeUi  
{ i D IY|  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), /'rj L<M  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), FfJp::|ddr  
nStartPos,nEndPos,i); "/aZ*mkjfJ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); j2MA['{  
fileSplitterFetch.start(); C e-ru)  
} K {' atc  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), l#KcmOz  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); G;G*!nlWf  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", rUb{iU;~m  
nEndPos = " + nFileLength); f=F:Af!  
// fileSplitterFetch[nPos.length-1].start(); w*VN=  
|q*yuK/  
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//等待子线程结束 .KA-=$~J1  
//int count = 0; [`\VgKeu  
//是否结束while循环 AOR?2u  
boolean breakWhile = false; i<^
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while(!bStop) |u>(~6  
{ x.+T65X~4  
write_nPos(); %Rc#/y  
Utility.sleep(500); JY,$B-l  
breakWhile = true; Zd[rn:9\  
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for(int i=0;i<nStartPos.length;i++) k<<x}=  
{ VhUWws3E  
if(!fileSplitterFetch.bDownOver) m^3x%
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{ \)~d,M}kK  
breakWhile = false; *4U_MM#rX  
break; =0g!Q  
} MYS`@%ZV#k  
} loVg{N:  
if(breakWhile) wXQxZuk[  
break; >3uNh:|>/  
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//count++; O k`}\NZL  
//if(count>4) yJ $6vmQ  
// siteStop();
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} 4Hj)Av<O(  
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System.err.println("文件下载结束！"); 6m:$mhA5  
} GmHDG-  
catch(Exception e){e.printStackTrace ();} [Yt{h9  
} hC\ l \y  
(s3k2Z  
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//获得文件长度 k H.dtg_  
public long getFileSize() r:g\  
{ f$C{Z9_SX  
int nFileLength = -1; EqW~

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try{ L kK *.  
URL url = new URL(siteInfoBean.getSSiteURL()); Ul}RT xJ
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Dkz/hg:q  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;qWu8\T+  
-5<[oBL;  
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int responseCode=httpConnection.getResponseCode(); ZxF`i>/h  
if(responseCode>=400) <fUo@]Lv   
{ 1h$?,  
processErrorCode(responseCode); Nz dN4+  
return -2; //-2 represent access is error *S,~zOYN  
} wMW<lT=;  
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String sHeader; #t ;`  
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for(int i=1;;i++) UGcmzwE  
{ ?:"ABkL|+Y  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); /v 8"i^;}  
//Utility.log(in.readLine()); sINQ?4_8T  
sHeader=httpConnection.getHeaderFieldKey(i); |:eTo<  
if(sHeader!=null) F3|^b{'zO  
{ HRf;bKZ  
if(sHeader.equals("Content-Length")) 6w^P{%ul  
{ [Hh-F#|R  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); | b'Ut)E  
break; yK*vn]}  
} Nr4}x7  
} o[ 5dR<  
else OC=&!<  
break; c*IrZm
  
} CRb*sfKDL  
} cN,*QN  
catch(IOException e){e.printStackTrace ();} @DysM~I  
catch(Exception e){e.printStackTrace ();} AQ,lLn+  
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Utility.log(nFileLength); UoT`/.  
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return nFileLength; t13V>9to  
} }5 rR^ryA  
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//保存下载信息（文件指针位置） tguB@,O  
private void write_nPos() noWF0+%  
{ '/>Mr!H#  
try{ uxfh?gsL  
output = new DataOutputStream(new FileOutputStream(tmpFile)); [q9B"@X  
output.writeInt(nStartPos.length); aXe&c^AR  
for(int i=0;i<nStartPos.length;i++) >=@-]X2%j  
{ &N}"4  
// output.writeLong(nPos); Ju+3}  
output.writeLong(fileSplitterFetch.nStartPos); wps/{h,  
output.writeLong(fileSplitterFetch.nEndPos); u&zY>'}zm  
}  [Sm<X  
output.close(); ('&lAn  
} )@wC6Ij  
catch(IOException e){e.printStackTrace ();} Xh"9Bcjf  
catch(Exception e){e.printStackTrace ();} D \ rns+  
} _o~ pVBl/  
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//读取保存的下载信息（文件指针位置） _}R$h=YD  
private void read_nPos() x1gS^9MqCB  
{ (5$Ge$  
try{ Myc-lCE  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); K,S4  
int nCount = input.readInt(); =R5W KX  
nStartPos = new long[nCount]; \[G'cE  
nEndPos = new long[nCount]; 2!%)_<  
for(int i=0;i<nStartPos.length;i++) "VaWZ*  
{ 1Yb&E7j  
nStartPos = input.readLong(); A]bb*a1  
nEndPos = input.readLong(); 4%0s p  
} T}Tv}~!f  
input.close(); h"[B zX
  
} F,_L}  
catch(IOException e){e.printStackTrace ();} T!jh`;D+  
catch(Exception e){e.printStackTrace ();} kK5&?)3Y:  
} fN2Sio:  
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private void processErrorCode(int nErrorCode) 24wDnDyh  
{ pm O9mWq   
System.err.println("Error Code : " + nErrorCode); Bl\:YYd  
} vQ< ~-E  

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//停止文件下载 S*l/ Sa@  
public void siteStop() lT[,w9$  
{ YnpN -Y%g  
bStop = true; vP{i+s18B  
for(int i=0;i<nStartPos.length;i++) eU"yF >6'  
fileSplitterFetch.splitterStop(); ?+}Su'pv}  
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} Tg)F.):  
} [Qs`@u<%  
//负责部分文件的抓取 z83v J*.  
**FileSplitterFetch.java MZ38=nJ  
*/ s9C^Cy^su  
package NetFox; A f`Kg-c_(  
e=LrgRy+  

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import java.io.*; c|<F8n  
import java.net.*; <0';2yP"  
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public class FileSplitterFetch extends Thread { T#*,ME7|m  
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String sURL; //File URL $z!G%PO1%  
long nStartPos; //File Snippet Start Position +c8`N'
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long nEndPos; //File Snippet End Position (H:c80/V  
int nThreadID; //Thread's ID &l cfX\y  
boolean bDownOver = false; //Downing is over Pz50etJ  
boolean bStop = false; //Stop identical
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FileAccessI fileAccessI = null; //File Access interface mX|M]^_,z  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {)Wf[2zJ  
{ e\~nqKCb  
this.sURL = sURL; D@p{EH  
this.nStartPos = nStart; j~_iv~[  
this.nEndPos = nEnd; JOuy_n  
nThreadID = id; cPcH 8Vd  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 bEF2-FO  
} W9l](Ow  
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public void run() x((u  
{ /- Gq`9Z  
while(nStartPos < nEndPos && !bStop) XR]bd  
{ = V')}f~C  
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try{ [!U%''  
URL url = new URL(sURL); H%vgPQ8  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6,4vs+(|\  
httpConnection.setRequestProperty("User-Agent","NetFox"); Wpf~Ji6||  
String sProperty = "bytes="+nStartPos+"-"; I3 6@x`f  
httpConnection.setRequestProperty("RANGE",sProperty); 5ppr;QaB  
Utility.log(sProperty); ,i6U*  
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InputStream input = httpConnection.getInputStream(); !{,2uQXe  
//logResponseHead(httpConnection); :Xy51p`.;]  
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byte[] b = new byte[1024]; @=G[mc\  
int nRead; (<B%Gy@  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) cQ$[Ba  
{ $@s-OQ}  
nStartPos += fileAccessI.write(b,0,nRead); WCY._H>|   
//if(nThreadID == 1) 0vEQgx>  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); qbQdxKk  
} .0,G4k/yv  
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Utility.log("Thread " + nThreadID + " is over!"); t[;-gi,,  
bDownOver = true; 5OPvy,e6  
//nPos = fileAccessI.write (b,0,nRead); G5|nt#>  
} v~x`a0  
catch(Exception e){e.printStackTrace ();} c)Ng9p  
} {|$kI`h,3-  
} cRs\()W  
$$Tf1hIg  
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//打印回应的头信息 .|CoueH  
public void logResponseHead(HttpURLConnection con) f#Ud=& >j  
{ o5RvxGN  
for(int i=1;;i++) ,2
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{ W)Mz1v #s  
String header=con.getHeaderFieldKey(i); =,6X_m  
if(header!=null) s/t,6-~EH  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); N G vb]  
Utility.log(header+" : "+con.getHeaderField(header)); 3rMi:*?  
else 7[ n
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break; g?iZ RM  
} mS}.?[d"  
} > {d9z9O  
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public void splitterStop() ;9#%E  
{ E3{kH 7_'\  
bStop = true; Vug[q=i  
} 'I}wN5`  
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} >bI\pJ  

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/* t
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**FileAccess.java \'zloBU  
*//文件访问(定位，写) Jj0:p"  
package NetFox; \d.\M  
import java.io.*; 'ahz@+lO  
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public class FileAccessI implements Serializable{ ffI=Bt]t  
d%L/[.&  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 `c^">L  
RandomAccessFile oSavedFile; 4KHIUW$  
long nPos; }!r pH{y  
Ll%}n
ti  
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public FileAccessI() throws IOException +2p}KpOsL  
{ !]fSS)\H  
this("",0); pKLNBR|  
} oV9{{  
9:3`LY3wW  
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public FileAccessI(String sName,long nPos) throws IOException gw">xt5  
{ Kv:.bHN}  
oSavedFile = new RandomAccessFile(sName,"rw"); jUZ$vyT  
this.nPos = nPos; y"8,jm  
oSavedFile.seek(nPos); `WMU'ezF  
} *aFh*-Sj2I  
(["V( $  
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public synchronized int write(byte[] b,int nStart,int nLen) ang~_Ec.  
{ F.@|-wq&  
int n = -1; p1.3)=T  
try{ X$~T*l0  
oSavedFile.write(b,nStart,nLen); p<mBC2!%  
n = nLen; .h/2-pQ>  
} S !lrnH  
catch(IOException e) Wwr  
{ A42!%>PB  
e.printStackTrace (); ']sjW'~  
} y,OG9iD:h  
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return n; xDPR^xY  
} ?|Z~mE  
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} GjN6Af~}  
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/* TI2K_'  
**SiteInfoBean.java 2qVoe}F  
*/ 0DnOO0Nc  
package NetFox; f<oU"WM  
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public class SiteInfoBean { WCk. K  
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private String sSiteURL; //Site's URL O:~J_Wwl!  
private String sFilePath; //Saved File's Path MXDCOe~07  
private String sFileName; //Saved File's Name  !I&,!$  
private int nSplitter; //Count of Splited Downloading File P1^|r}  
3xdJ<Lrq  
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public SiteInfoBean() pp{p4Z   
{//nSplitter的缺省值为5 V[Sj+&e&  
//default value of nSplitter is 5 a2]ZYY`R7  
this("","","",5); K3WaBcm  
} mfffOG  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 8^_e>q*W  
{ mH\2XG8nV  
sSiteURL= sURL; <5#2^
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sFilePath = sPath; nz#eJ  
sFileName = sName;  T-+ uQ3  
this.nSplitter = nSpiltter; 'n\PS,[1R  
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} =}I=s@  
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public String getSSiteURL() 9d( M%F  
{ (J%>{?"ij  
return sSiteURL; 6hcK%0z  
} b5KK0Jjk  
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x;/dSfv_  
public void setSSiteURL(String value) >Y+m54EE  
{ gNDMJ^`  
sSiteURL = value; t. (6tL]  
} =8rNOi  
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public String getSFilePath() AGO"),  
{ V,8Z!.MG  
return sFilePath; :>_oOn[_  
} F!4V!VWA}  
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N>Uxq&)!  
public void setSFilePath(String value) |;d#k+/;
 
{ 4gVIuF*pS  
sFilePath = value; 4vvQ7e7  
} R(8?9-w  
%XZhSmlf
 
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public String getSFileName() f|F=)tJO  
{ :qAX9T'{t  
return sFileName; % -+7=x  
} 3)2{c  
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p&)d]oV>  
public void setSFileName(String value) x%[NK[^&  
{ hsYE&Np_Q  
sFileName = value; .=d40m  
} PyK!Cyq  
\IudS{ .?;  
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public int getNSplitter() Qgv g*KX  
{ D/;[x{;E  
return nSplitter; YTTij|(  
} G-R83Orl  
bu $u@:q 6  
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public void setNSplitter(int nCount) loE;q}^  
{ esQ`6i  
nSplitter = nCount; UWK|_RT6SA  
} kCoE;)y$  
} G
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/* gN73)uJ0  
**Utility.java D`'Cnt/  
*/ Br42Qo2"T>  
package NetFox; VN\VTSZh?\  
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public class Utility { =VT\$ 5A  
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public Utility() /`nkz  
{ ]sE)-8  
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} FZZO-,xa  
~3Zz.!F  
//线程睡眠 nD]M
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public static void sleep(int nSecond) ("}C& 6)cB  
{ EE`[J0 (  
try{ F#RNm5  
Thread.sleep(nSecond); x2r.4  
} W\5 -Yg(@  
catch(Exception e) qbCU&G|)  
{ f1elzANy  
e.printStackTrace (); :PY6J}:&#  
} 1CSGG'J]E  
} ]\oT({$6B  
1;i|GXY:h  
//日志 4GG>n  
public static void log(String sMsg) #n15_cd  
{ q8;MPXSG3  
System.err.println(sMsg); 4`fV_H.8  
} k'PvQl"I  
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public static void log(int sMsg) ~-uf%=  
{ j
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System.err.println(sMsg); R#8cOmZ  
} 7 b(  
} YjJ^SU`*  
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/* 8O60pB;4  
**TestMethod.java 5JK'2J&  
*/ |:4?K*w",  
package NetFox; ],~[^0  
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@g+v2(f2v  
public class TestMethod { kdx06'4o  
DHuvHK0#  
5} ur,0{  
public TestMethod() <sM_zoprc  
{ ///xx/weblogic60b2_win.exe ?*r%*CL  
try{ ZU`~@.`i  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); BYHyqpP9  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); JKO*bbj  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 7ncR2-{g  
fileFetch.start(); pR=R{=}wV
 
} >,'guaa  
catch(Exception e){e.printStackTrace ();} Y6hV ;[\F  
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} {Oq8A.daJ  
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public static void main(String[] args) I>vU
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{ ggkz fg&  
new TestMethod(); u^c/1
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} XeY[;}9  
} 9) $[W  
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