http断点续传简单实现（java)

/* |Syulus  
**SiteFileFetch.java >%c>R'~h  
*/ <SSkCw  
package NetFox; r_Pi)MPc  
import java.io.*; C!|Yz=e  
import java.net.*; fjqd16{Q  
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public class SiteFileFetch extends Thread { 2zkOs:  
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SiteInfoBean siteInfoBean = null; //文件信息Bean +o K*5 Y  
long[] nStartPos; //开始位置 #?DoP]1
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long[] nEndPos; //结束位置 ($,qxPOn  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 N@I=X-7nh|  
long nFileLength; //文件长度 TV?MB(mN  
boolean bFirst = true; //是否第一次取文件 ey`E E/WV  
boolean bStop = false; //停止标志 ;y-sd?pAk  
File tmpFile; //文件下载的临时信息 |0VZ1{=*  
DataOutputStream output; //输出到文件的输出流 +-Z `v  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） E_#?;l>  
public SiteFileFetch(SiteInfoBean bean) throws IOException ^K:-r !v^  
{ |}o3EX  
siteInfoBean = bean; 2I_~]X53[  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 3yLJWH
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); U<6+2y P  
if(tmpFile.exists ()) 9[:TWvd  
{
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bFirst = false; wAc;
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read_nPos(); ;eW\41w  
} 5i=C?W`'  
else 5a5)hmO RB  
{ T1(*dVU?  
nStartPos = new long[bean.getNSplitter()]; CEBa,hp@  
nEndPos = new long[bean.getNSplitter()]; gCx#&aXS  
} 2u(G:cR  
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} ,hE989x<iI  
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public void run() @el  
{ pz]!T'  
//获得文件长度 EvF[h:C2  
//分割文件 v4,Dt  
//实例FileSplitterFetch *$@u`nM  
//启动FileSplitterFetch线程 A}(o1wuw  
//等待子线程返回 H`rd bE  
try{ (btmg<WT"  
if(bFirst) H4<Q}([w  
{ V+t's*9o3  
nFileLength = getFileSize(); l\ VrD2j8  
if(nFileLength == -1) $t0JfDd6Ky  
{ _7'5IA  
System.err.println("File Length is not known!"); upGLZ#  
} _IWLC{%V  
else if(nFileLength == -2) gKtgW&PYm  
{ Cl!9/l?z  
System.err.println("File is not access!"); [OR"9W&  
} bbT$$b-  
else DTHWL  
{ P=Su)c  
for(int i=0;i<nStartPos.length;i++) z#2n+hwE  
{ |^"0bu"  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); S:1g(f*85  
} ,(NN)Oj  
for(int i=0;i<nEndPos.length-1;i++) h=B= J  
{ >~_)2_j  
nEndPos = nStartPos[i+1]; eg24.W9c  
} N! I$Qtr,  
nEndPos[nEndPos.length-1] = nFileLength; R[OXYHu  
} MfO:BX@$  
} J M`[|"R%  
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//启动子线程 my#\(E+  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; R[@}Lg7+v  
for(int i=0;i<nStartPos.length;i++) X!m lC51  
{ ],Yy)<e.  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3cF8DNh  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), /*MioaQB}p  
nStartPos,nEndPos,i); _PSOT5{  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (p<pF].  
fileSplitterFetch.start(); }b/P\1#z  
} Nnq1&j"m  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), iUk#hL
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); zE~Xxp  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", o7@C$R_#  
nEndPos = " + nFileLength); zjOOEvi  
// fileSplitterFetch[nPos.length-1].start(); cQm4q19  
 K
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//等待子线程结束 P>(FCX  
//int count = 0; ;; ;=)'o  
//是否结束while循环 n~.$
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boolean breakWhile = false; GxEShSGOE  
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while(!bStop) 6@eF|GoP  
{
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write_nPos(); E;[Uhh|78!  
Utility.sleep(500); GP^.h kVs  
breakWhile = true; 'by+hXk  
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for(int i=0;i<nStartPos.length;i++) dCeLW  
{ Nd&UWk^  
if(!fileSplitterFetch.bDownOver) XK})?LTD  
{ Keem\/  
breakWhile = false; ZJ.a
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break; SMzq,?-`  
} n2EPx(~  
} Hq!|r8@6  
if(breakWhile) *ifz@8C }  
break; 5{Q9n{dOh  
p4 =/rkq  
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//count++; hS&l4 \I'Z  
//if(count>4) ,~DV0#"  
// siteStop(); ZvMU3]
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} um}q@BU  
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System.err.println("文件下载结束！"); cnI5G!  
} @bJIN]R  
catch(Exception e){e.printStackTrace ();} -$DfnAh  
} v; R2,`[W  
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8;r#HtFM  
//获得文件长度 *0to,$ n  
public long getFileSize() i;-M8Q^  
{ dDIR~!T  
int nFileLength = -1; ]!&$&t8.  
try{ Y~e)3e  
URL url = new URL(siteInfoBean.getSSiteURL()); <fM}Kk  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Fm,` ]CO  
httpConnection.setRequestProperty("User-Agent","NetFox"); `j(._`8%a  
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int responseCode=httpConnection.getResponseCode(); CH&{x7$he  
if(responseCode>=400) ml<tH2Qx3C  
{ .
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processErrorCode(responseCode); y^ |u'
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return -2; //-2 represent access is error ],k~t5+  
} ][ IOlR  
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String sHeader; U3Z=X TB  
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for(int i=1;;i++) ^6z"@+;*  
{ =$fz</S=J  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); KmTFJ,iM  
//Utility.log(in.readLine()); w"wW0uE^  
sHeader=httpConnection.getHeaderFieldKey(i); b^Re947{g  
if(sHeader!=null) gXJBb+P   
{ Q
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if(sHeader.equals("Content-Length")) e6Y>Bk  
{ t>/x-{bH\  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); )*>wa%[-q  
break;
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} y<E];ub  
} sQac%.H;`U  
else  dC{dw^  
break; 
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} *LU/3H|}  
} q]I aRho  
catch(IOException e){e.printStackTrace ();} j~G(7t  
catch(Exception e){e.printStackTrace ();} b%%r`j,'JE  
{;u,04OVK  
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Utility.log(nFileLength); !@F {FR  
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return nFileLength; %,_ZVgh0  
} Xt<1b
 
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//保存下载信息（文件指针位置） "(7y%TFt:  
private void write_nPos()  }o*A>le  
{ )q-NE)  
try{ Syy{ ^Ae}  
output = new DataOutputStream(new FileOutputStream(tmpFile)); rZJJ\ , |  
output.writeInt(nStartPos.length); e,/]]E/o  
for(int i=0;i<nStartPos.length;i++) ZK+F<}  
{ jDpA>{O[  
// output.writeLong(nPos); 94BH{9b5  
output.writeLong(fileSplitterFetch.nStartPos); ={sjoMW  
output.writeLong(fileSplitterFetch.nEndPos); uR5+")r@S  
} 3NL
n}  
output.close(); g"1V]  
} jts0ZFHc-  
catch(IOException e){e.printStackTrace ();} iX]OF.:   
catch(Exception e){e.printStackTrace ();} J<QZ)<T,&  
} TA-2{=8  
:LY.C<8  
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//读取保存的下载信息（文件指针位置） jJ$B^Y"4  
private void read_nPos() !SW0iq[7j  
{ <@KIDZYC  
try{ \+%~7Bi]z  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ~p?A
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int nCount = input.readInt(); XNWtX-[^@  
nStartPos = new long[nCount]; e^>>"tr  
nEndPos = new long[nCount]; ~3?-l/$  
for(int i=0;i<nStartPos.length;i++) V%r`v%ktF  
{ /DHgwpJ  
nStartPos = input.readLong(); hbH~Ya=+S  
nEndPos = input.readLong(); <v|"eq}  
} ,bl }@0A  
input.close(); ]yf?i350  
} kk-<+R2  
catch(IOException e){e.printStackTrace ();} RTcxZ/\"#  
catch(Exception e){e.printStackTrace ();} dDpAS#'s\  
} (4
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.
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private void processErrorCode(int nErrorCode) k i<X^^  
{ 9f( X7kt  
System.err.println("Error Code : " + nErrorCode); :}zyd;Rc  
} |NZi2Bu  
v"o"W[  
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//停止文件下载 U]sAYp^$  
public void siteStop() SWV*w[X<X  
{ U.Mfu9}#:  
bStop = true; )OV0YfO  
for(int i=0;i<nStartPos.length;i++) [! $NTt_  
fileSplitterFetch.splitterStop(); Y7}Tuy dC  
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} noxJr/A]  
} eut2x7Z(c  
//负责部分文件的抓取 iQgg[ )  
**FileSplitterFetch.java 8@m$(I+  
*/ 5 3%>)gk:  
package NetFox; 2F:qaz  
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import java.io.*; fZo#
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import java.net.*; T?pS2I~  
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public class FileSplitterFetch extends Thread { (?r,pAc:  
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String sURL; //File URL A9MM^jV8  
long nStartPos; //File Snippet Start Position <giBL L!  
long nEndPos; //File Snippet End Position 10FiA;  
int nThreadID; //Thread's ID |:1{B1sqA  
boolean bDownOver = false; //Downing is over .xsfq*3e5  
boolean bStop = false; //Stop identical N;g@lyo  
FileAccessI fileAccessI = null; //File Access interface ^<CVQ8R7  
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.  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException @Dh2@2`>  
{ FOXSs8"c]!  
this.sURL = sURL; LORcf1X/  
this.nStartPos = nStart; k7CKl;Fck  
this.nEndPos = nEnd; YZg#H)w%  
nThreadID = id; t WI-  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 AoS7B:T;!  
} ~5N}P>4*  
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public void run() HT;^
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{ bE_8NA"2  
while(nStartPos < nEndPos && !bStop) 8>v_th  
{ w>%@Ug["  
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try{ }D#:NlMp  
URL url = new URL(sURL); DzAZv/h76  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;V}:0{p
 
httpConnection.setRequestProperty("User-Agent","NetFox"); CxFd/X,  
String sProperty = "bytes="+nStartPos+"-";  %!<Y  
httpConnection.setRequestProperty("RANGE",sProperty); ;7
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Utility.log(sProperty); |\,OlX,  
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InputStream input = httpConnection.getInputStream(); XnyN*}8  
//logResponseHead(httpConnection); QKG3>lU  
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byte[] b = new byte[1024]; npdljLN  
int nRead; 928_e)V  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ue_wuZi  
{ I^
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nStartPos += fileAccessI.write(b,0,nRead); UY',n,  
//if(nThreadID == 1) ^jL '*&l  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); R BYhU55B  
} |6E_N5~  
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Utility.log("Thread " + nThreadID + " is over!"); 9bM\ (s/  
bDownOver = true; <Riz!(G  
//nPos = fileAccessI.write (b,0,nRead); 5C Dk5B_  
} [4z,hob  
catch(Exception e){e.printStackTrace ();} p#@#$u-  
} VfoWPyWD#  
} _ \D%  
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//打印回应的头信息 Rf:.'/<
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public void logResponseHead(HttpURLConnection con) l(t&<O(m9  
{ AC,RS7  
for(int i=1;;i++) -o ).<&#  
{ FdU]!GO-X  
String header=con.getHeaderFieldKey(i); ]\(8d[4  
if(header!=null) s4|\cY`b-  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 7r:h_r-  
Utility.log(header+" : "+con.getHeaderField(header)); QN:v4,$d  
else vF72#BNs  
break;
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} PYkhY;*  
} M+/G>U  
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public void splitterStop() H1bR+2s  
{ I3t5S;_8  
bStop = true; #D`@
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} XM$~HG  
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} G3.a
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/* rAenxZ,tF  
**FileAccess.java mWp>E`l  
*//文件访问(定位，写) zggnDkC5  
package NetFox; J@3,  
import java.io.*; ^m>4
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/fI}QY1  
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public class FileAccessI implements Serializable{ cAWn*%  
=xI;D,@S  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 IKD{3cVL  
RandomAccessFile oSavedFile; - x  
long nPos; 9[0iIT$q$  
v] m/$X2  
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public FileAccessI() throws IOException xTHD_?d  
{ WTSh#L  
this("",0); yaUtDC.|  
} pjeNBSu6  
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public FileAccessI(String sName,long nPos) throws IOException &G{GLP?H  
{ &o:5lxR{  
oSavedFile = new RandomAccessFile(sName,"rw"); q W(@p`  
this.nPos = nPos; M:+CW;||!  
oSavedFile.seek(nPos); ,-UF5U  
} KOcB#UHJ  
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;:;E|{e  
public synchronized int write(byte[] b,int nStart,int nLen) UK=ELvt]  
{ ,.,8-
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int n = -1; .;? Bni  
try{ DX_mrG  
oSavedFile.write(b,nStart,nLen); z:QDWH  
n = nLen; :'%6
  
} g4?2'G5m?  
catch(IOException e) }lZEdF9GhG  
{ GBJLB  
e.printStackTrace (); bvox7V>  
} "HOZ2_(o  
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return n; T4eJ:u*;  
} #6 M]tr  
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} *^?tr?e%I<  
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te@m#`p9  
/* T;w:^XW  
**SiteInfoBean.java [,=?e  
*/ P\U<,f  
package NetFox; qt8Y3:=8l  
*!5CL'  
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public class SiteInfoBean { u~uzKG  
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private String sSiteURL; //Site's URL 6
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private String sFilePath; //Saved File's Path ghQ B  
private String sFileName; //Saved File's Name ?t/qaUXN  
private int nSplitter; //Count of Splited Downloading File (,Y[2_Zv  
-&/?&{Q0  
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public SiteInfoBean() ZrN(Mp  
{//nSplitter的缺省值为5 &;PxDlY5  
//default value of nSplitter is 5 ^y5A\nz&  
this("","","",5); [$y(>]~.  
} dX[I :,z*  
j=sfE qN).  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) TOG:`F
ID  
{ 7[ ovEE54  
sSiteURL= sURL; +gl\l?>sr  
sFilePath = sPath; Y\ [|k-6  
sFileName = sName; Aztrq  
this.nSplitter = nSpiltter; F^dJ{<yX  
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WK%cbFq(  
} XYcZ;Z9:  
I9?\Jbqg  
+Mj6.X  
public String getSSiteURL() ;lMvxt:  
{ 0R?1|YnB  
return sSiteURL; 5`h 6oFxGp  
} @c~Z0+Ji  
>X~B1D,SV7  
*yZ6"  
public void setSSiteURL(String value) Ww<Y]H$xZ<  
{ 4D65VgVDM  
sSiteURL = value; 1*O|[W  
} 0]d;)_`@  
[YvS#M3T  
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public String getSFilePath() U9 iI2$  
{ H,> }t S  
return sFilePath; (-C)A-Uo&  
} A 3 V  
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u
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public void setSFilePath(String value) K^WDA]
)  
{ .; MS78BR  
sFilePath = value; 1RAkqw<E  
} f+e"`80$*C  
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public String getSFileName() >}SEU-7&\  
{ GcO2oq  
return sFileName; `KQx#c>'  
}
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public void setSFileName(String value) :WB uU  
{ '#Wx@  
sFileName = value; M=,pn+}y>  
} %&L13:  
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public int getNSplitter() BJ UG<k  
{ :zL)O  
return nSplitter; .}__XWK5  
} CW1l;uwtU  
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public void setNSplitter(int nCount) Tm"H9  
{ p4T$(]7  
nSplitter = nCount; ')jItje|  
} '
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} -Y_, .'ex  
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/* x?AG*' h&  
**Utility.java yY VR]HH  
*/ p]aEC+q  
package NetFox; qT#e -.G  
).KA0-  
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public class Utility { gWj-@o\  
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;yNc7Vl  
public Utility() H(y`[B,}*  
{ \%7*@&  
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} M+ [ho]  
~kW?]/$h  
//线程睡眠 JBY.er`6C  
public static void sleep(int nSecond) Nh\vWAz9  
{ 'rhgM/I  
try{ Lu#qo^  
Thread.sleep(nSecond); ,z&S;
f.f  
} R+LKa Z  
catch(Exception e) 1Vpti4OmU  
{ rC8p!e.yL  
e.printStackTrace (); #-yCR  
} Lx,=Up.  
} >)M{^  
Z],j|rWy6  
//日志 ;21D^e  
public static void log(String sMsg) ytttF5-  
{ Odwe1q&  
System.err.println(sMsg); +O/b[O'0  
} 2^r~->  
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2cCiHEL#  
public static void log(int sMsg) `n&
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{ zQ,rw[C"W  
System.err.println(sMsg); R4p Pt  
} ]-gyXE1.r  
} Tpl]\L1v-  
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D:T]$<=9  
/* i{^T;uAE  
**TestMethod.java &ijz'Sg3  
*/ ]dUG=dWO  
package NetFox; _a$qsY  
bYsX?0T!p  
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public class TestMethod { lDL&":t  
`2Pa{g-.  
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public TestMethod() 6ll!7U(9(  
{ ///xx/weblogic60b2_win.exe VWft/2p~  
try{ 5/"$_7"{a  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ~i|6F~%3  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); b,'O|s]"Sc  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 01A{\O1$j  
fileFetch.start(); 9q'&tU'a=c  
} X%yG{\6:  
catch(Exception e){e.printStackTrace ();} :[CV_ME.;  
}$_@yt<{W@  
8?Zhh.  
} C hF~  
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public static void main(String[] args) t6"%u3W8M  
{ 6?a`'&  
new TestMethod(); l*l*5hA  
} _=mzZe[  
} '|[!I!WB`  
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