http断点续传简单实现（java)

/*
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**SiteFileFetch.java .ou#BWav/  
*/ 0*4h}t9j  
package NetFox; "Vw;y+F}  
import java.io.*; WU:r:m+ >  
import java.net.*; ;zpSyyp@  
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public class SiteFileFetch extends Thread { s9\HjK*+  
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SiteInfoBean siteInfoBean = null; //文件信息Bean p]^?4  
long[] nStartPos; //开始位置 ]!mC
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long[] nEndPos; //结束位置 ;*AKeI2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 D,( "3zx  
long nFileLength; //文件长度 %Jb/HWC[  
boolean bFirst = true; //是否第一次取文件 Wf>P[6  
boolean bStop = false; //停止标志 FHv^^
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File tmpFile; //文件下载的临时信息 P_y8[Y]?  
DataOutputStream output; //输出到文件的输出流 =)O%5<Lwx  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） h,Nq:"}  
public SiteFileFetch(SiteInfoBean bean) throws IOException EWZ?q$  
{ \|wUxijJ*,  
siteInfoBean = bean; ]N#%exBVo  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 2sXNVo8`w"  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); >vny9^_  
if(tmpFile.exists ()) ),%(A~\  
{ S+mM S  
bFirst = false; P)k!#*  
read_nPos(); *y@Xm~ld  
} R>CIEL  
else 8~6H\.0Q  
{ h!4jl0oX]  
nStartPos = new long[bean.getNSplitter()]; 2g`<*u*  
nEndPos = new long[bean.getNSplitter()]; qTV;L-  
} gd=gc<zYP  
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} (7k}ysc  
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public void run() a%igc^GS2  
{ OdWZYWj  
//获得文件长度 {OBV+}#  
//分割文件 ?ZS/`P0}[  
//实例FileSplitterFetch ]Lz:oV^%  
//启动FileSplitterFetch线程 -w3KBlo  
//等待子线程返回 L2$`S'UW  
try{ %7vjYvo>  
if(bFirst) Jp#Onl+d6  
{ J6s@}@R1  
nFileLength = getFileSize(); 'ai3f  
if(nFileLength == -1) wx]r{  
{ o)}M$}4  
System.err.println("File Length is not known!"); s ~Xa=_+D  
} ,!i!q[YkL9  
else if(nFileLength == -2) R{R'byre  
{ piPx8jT`F  
System.err.println("File is not access!"); r}%2;!T  
} hP$v,"$  
else MjrI0@R  
{ {%! >0@7  
for(int i=0;i<nStartPos.length;i++) K>_~zWnc  
{  |tVWmm^m  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); *F)+- BB  
} ]@G$L,3  
for(int i=0;i<nEndPos.length-1;i++) 5
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{ )h>H}wDs  
nEndPos = nStartPos[i+1]; ~;ZT<eCIA  
} )o[Jxu'  
nEndPos[nEndPos.length-1] = nFileLength; gK Uci  
} 5+yT{,(5  
} 1v2pPUH\  
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//启动子线程 ?VCM@{9  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; E,EpzB$_dj  
for(int i=0;i<nStartPos.length;i++) q8-*3
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{ //
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), M tD{/.D>  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Ak=|wY{  
nStartPos,nEndPos,i); >mXq= 9L4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); yG~7Xo5  
fileSplitterFetch.start(); wLW[Vur[  
} 6:$+"@ps  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 23|R $s>}i  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ?K9zTas@  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", l NhX)D^t  
nEndPos = " + nFileLength); \]$TBN dJ4  
// fileSplitterFetch[nPos.length-1].start(); +ia N[F$  
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//等待子线程结束 FsTl@zN  
//int count = 0; 1nAAs;`'  
//是否结束while循环 \7elqX`.yY  
boolean breakWhile = false; \[MQJX,dn  
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while(!bStop) ~IIlCmMl,  
{ 7!r)[2l  
write_nPos(); YI!@
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Utility.sleep(500); 9@{=2 k  
breakWhile = true; _4lhwKYU  
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for(int i=0;i<nStartPos.length;i++) '3'*VcL(  
{ iLR^V!  
if(!fileSplitterFetch.bDownOver) PEIf)**0N  
{ KsR^:_e  
breakWhile = false; A!n)Fpk  
break; S#g=
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} g]a5%8*{  
} .Km6 (U  
if(breakWhile) j 5{"j  
break; f;Uf=.#F  
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//count++; !^m,v19Ds<  
//if(count>4) S(MVL!Lm  
// siteStop(); `^#V1kRmH  
} eABLBsx  
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System.err.println("文件下载结束！"); rh+2 7"  
} Z<M?_<3  
catch(Exception e){e.printStackTrace ();} jJU9~5i?  
} B$)&;Q  
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//获得文件长度 qQ=\R1l  
public long getFileSize() b
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{ KB6'sj  
int nFileLength = -1; o n+:{ad  
try{ 2C@s-`b   
URL url = new URL(siteInfoBean.getSSiteURL()); kntM  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~4{|  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8&2W^f5  
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int responseCode=httpConnection.getResponseCode(); gI5"\"T{  
if(responseCode>=400) IP3%'2}-  
{ B+Ox#[<75  
processErrorCode(responseCode); C_q@ixF{  
return -2; //-2 represent access is error t.YY?5l  
} `:y
{  
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String sHeader; 1w|C+m/(  
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for(int i=1;;i++) Kp.d#W_TX
 
{ y?4%eD  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ^;[|,:8f7L  
//Utility.log(in.readLine()); H1^m>4ll9  
sHeader=httpConnection.getHeaderFieldKey(i); XzV:q!e-  
if(sHeader!=null) nJ{vO{N  
{ ehe;<A  
if(sHeader.equals("Content-Length")) #eKg!]4-R  
{ ?r"QJa>  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 6Rcl HU  
break; BGO!c
[-  
} C!%\cy%Xj  
} ,Q>RtV  
else E Qn4+  
break; [8OQ5}do/  
} 3|qT.QR`Z  
} 6^vseVx  
catch(IOException e){e.printStackTrace ();} Yj-JB  
catch(Exception e){e.printStackTrace ();} i=mk#.j~  
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Utility.log(nFileLength); c"H59 j
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d} {d5-_a  
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return nFileLength; x;; =+)Gg  
} _t'S<jTI  
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//保存下载信息（文件指针位置） gZ b+m  
private void write_nPos() -<MA\iSP  
{ QgZ`~  
try{ ljJi|+^$  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Iq%f*Zm<  
output.writeInt(nStartPos.length); FWu[{X;  
for(int i=0;i<nStartPos.length;i++) T|fmO<e*n  
{ :e|[gEA  
// output.writeLong(nPos); :1/K$A)^{  
output.writeLong(fileSplitterFetch.nStartPos); =mWr8p-H  
output.writeLong(fileSplitterFetch.nEndPos); 40ZHDtIu<  
} QhqXd  
output.close(); W7 iml|WV0  
} +q NX/F  
catch(IOException e){e.printStackTrace ();} |)'6U3  
catch(Exception e){e.printStackTrace ();} =}h8Cl{H/  
} ^S]-7>Yyr  
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//读取保存的下载信息（文件指针位置） Cvk n2T  
private void read_nPos() F]L$xU  
{ L UitY  
try{ S, g/2k*  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); M!Hn`_E  
int nCount = input.readInt(); dd=';%?  
nStartPos = new long[nCount]; G,]%dZHe  
nEndPos = new long[nCount]; WBIJ9e2~  
for(int i=0;i<nStartPos.length;i++) p#fd+  
{ Kx[u9MD  
nStartPos = input.readLong(); 7=e!k-G  
nEndPos = input.readLong(); HXY,e$c#y  
} =:~%$5[[  
input.close(); }g@5%DI
]  
} PRo;NE  
catch(IOException e){e.printStackTrace ();} Uw:gJ
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catch(Exception e){e.printStackTrace ();} Aqp$JM >  
} FdZG%N>Z  
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private void processErrorCode(int nErrorCode) +2WvGRC  
{ H/Wo~$  
System.err.println("Error Code : " + nErrorCode); I<v:xTor  
} mxxuD"5  
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} eL*gy  
//停止文件下载 _U%fD|t  
public void siteStop() .&Rj2d  
{ }%m:^*@$9  
bStop = true; [`'[)B  
for(int i=0;i<nStartPos.length;i++) L4wKG&  
fileSplitterFetch.splitterStop(); p=-:Z?EW1  
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} 3$E\B=7/U  
} \KpSYX1  
//负责部分文件的抓取 Vu u2SS  
**FileSplitterFetch.java 6n}5>GSF  
*/ afJ`1l  
package NetFox; rElbzL"&<  
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import java.io.*; TGe)%jZ  
import java.net.*; fQ@k$W\  
\
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public class FileSplitterFetch extends Thread { spVE'"^  
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String sURL; //File URL 68pB*(i  
long nStartPos; //File Snippet Start Position "N|gU;~W  
long nEndPos; //File Snippet End Position %%=PpKYtSD  
int nThreadID; //Thread's ID AlQE;4yX  
boolean bDownOver = false; //Downing is over $u`v k|\R  
boolean bStop = false; //Stop identical R"0fZENTG  
FileAccessI fileAccessI = null; //File Access interface 9*"Ae0ok1  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Ig*qn# Dd  
{ G{8>
 
this.sURL = sURL; 8D[,z 7n  
this.nStartPos = nStart; j![;;  
this.nEndPos = nEnd; 1E]|>)$  
nThreadID = id; X9lh@`3  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 fT&>L  
} k~<b~VcU  
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public void run() { 4(E @  
{ GOx+%`.R\  
while(nStartPos < nEndPos && !bStop) 0!^vQ  
{ <o\2-fWvY  
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try{ svBT~P0x  
URL url = new URL(sURL); 2?)bpp$WZ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~MOab e  
httpConnection.setRequestProperty("User-Agent","NetFox"); Rp!R&U/  
String sProperty = "bytes="+nStartPos+"-"; }E}b/ulg1  
httpConnection.setRequestProperty("RANGE",sProperty); pu"`*NL  
Utility.log(sProperty); 3O W)%  
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InputStream input = httpConnection.getInputStream(); `(RQh@H  
//logResponseHead(httpConnection); ylEQeN  
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byte[] b = new byte[1024]; ?2#v`Z=L;  
int nRead; "HuV'  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) !E0zj9 [ R  
{ R-8/BTls7  
nStartPos += fileAccessI.write(b,0,nRead); \U1fUrw$*  
//if(nThreadID == 1) s /?&H-  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `?X=
@  
} \;b)qB  
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Utility.log("Thread " + nThreadID + " is over!"); c]y"5;V8  
bDownOver = true; 2!Mwui;%  
//nPos = fileAccessI.write (b,0,nRead); P[.BK  
} |kUxTe  
catch(Exception e){e.printStackTrace ();} b0~AN#Es  
} ~m]sJpW<"  
} 5K~kzRL$r  

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//打印回应的头信息 :[#~,TW  
public void logResponseHead(HttpURLConnection con) }P5zf
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{ _Gpq=(q
)  
for(int i=1;;i++) 4|&7j7<u  
{ 0NN{2"M$p  
String header=con.getHeaderFieldKey(i); l>Nz]Ul%{  
if(header!=null) $9}z^sGIM  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); P&ig.Og*  
Utility.log(header+" : "+con.getHeaderField(header)); 78s:~|WB<{  
else d" "GG/  
break; &*}NN5Sv  
} T@n-^B!Xq  
} Zl0Kv*S  
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public void splitterStop() 5 W<\J  
{ x<0-'EF/S  
bStop = true; \~(ww3e  
} {|}tp<:2  
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} Wp0e?bK_  
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/* KP
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**FileAccess.java `Z3Qx~fx  
*//文件访问(定位，写) 0L34)W  
package NetFox; hrwQh2sm  
import java.io.*; hSgfp  
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public class FileAccessI implements Serializable{ Ek [V A\G  
C] <K s  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 VQm)32'  
RandomAccessFile oSavedFile; C-
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long nPos; t|gEMDGa3  
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public FileAccessI() throws IOException (c/H$'  
{ vrtK~5K  
this("",0); %$b)l?!  
} k,L,  
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public FileAccessI(String sName,long nPos) throws IOException \#(cI  
{ E^.y$d~dS  
oSavedFile = new RandomAccessFile(sName,"rw"); G`9\v
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this.nPos = nPos; uzO%+B!  
oSavedFile.seek(nPos); f\Bd lOJ>  
} }+[H~8)5  
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public synchronized int write(byte[] b,int nStart,int nLen) m6aq_u{W  
{ Ni5~Buf  
int n = -1; la ~T)U7  
try{ pV#~$e  
oSavedFile.write(b,nStart,nLen); ?_e2)+q8YG  
n = nLen; ."R,j|o6  
} $73j*@EQA  
catch(IOException e) v535LwFW  
{ 7qB}Hvh  
e.printStackTrace (); }5H3DavW  
} h1.]Nl C  
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return n; '`q&UPg]  
} *P_ 3A:_  
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} x+zz:^yHYf  
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/* AZ)H/#b
e  
**SiteInfoBean.java @[0zZX2EE  
*/ m~%\f8w-x  
package NetFox; p=U*4[9k  
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public class SiteInfoBean { fX).A`  
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private String sSiteURL; //Site's URL <4z |"(  
private String sFilePath; //Saved File's Path B$aA=+<S  
private String sFileName; //Saved File's Name :E/]Bjq$;  
private int nSplitter; //Count of Splited Downloading File ^[}^+  
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public SiteInfoBean() *%L:soM'Ll  
{//nSplitter的缺省值为5 Rh-e C6P  
//default value of nSplitter is 5 !/G2vF"  
this("","","",5); +Zu*9&Cx  
} `}gjfu -'\  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) fu3/n@L  
{ w-?_U7'  
sSiteURL= sURL; dzMlfJp  
sFilePath = sPath; 4l+"J:,  
sFileName = sName; `_C4L=q"  
this.nSplitter = nSpiltter; 5v4 ,YHD  
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} C-/<5D j  
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public String getSSiteURL() tz-, |n0  
{ ec/1Z8}p  
return sSiteURL; =$6z1] ;3  
} \Tf845  
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public void setSSiteURL(String value) tgy*!B6a~  
{ |Id0+-V ?  
sSiteURL = value; 8%]o6'd4  
} h.@
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public String getSFilePath() ,$ L>  
{ )%lPa|7s  
return sFilePath; [V_Z9-f*  
} bhaIi>W~G  
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public void setSFilePath(String value) 4$LVl  
{ UN'[sHjOnD  
sFilePath = value; 6('2.^8  
} ?zW4|0  
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public String getSFileName() ,h,DB=!K<  
{ /1ZRjf^  
return sFileName; cl kL)7RQ  
} Lu,72i0O ^  
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public void setSFileName(String value) 2TB>d+  
{ ssGp:{]v/  
sFileName = value; e?FjN 9  
} 33dHTV  
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public int getNSplitter() ZYr6Wn  
{ k^B<t'  
return nSplitter; D+G?:mR  
} $'#hCs  
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public void setNSplitter(int nCount) g,Z8I;A^  
{ IzPnbnS}  
nSplitter = nCount; qyzmjV6J2  
} ~R-P%l P  
} H/"$#8-/  
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/*
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**Utility.java SPfz/ q{  
*/ W]b>k lp;  
package NetFox; m{T:<:q~  
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public class Utility { v4c*6(m  
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public Utility() 
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{ '/l<\b/E  
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} 9yla &XTD  
8$)xxV_zp  
//线程睡眠 ;7,>2VTm  
public static void sleep(int nSecond) f@Oi$9CZn  
{ Fo\* Cr9D  
try{ d)hA'k  
Thread.sleep(nSecond); X0a)6HZ{  
} Egy#_ RT{  
catch(Exception e) 
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{ r"HQ>Wn  
e.printStackTrace (); ZSWKVTi  
} pjG/`  
} 'Lm\ r+$F  
f_\,H|zco)  
//日志 yhTC?sf<  
public static void log(String sMsg) L>xecep  
{ FFC"rG  
System.err.println(sMsg); ~)ut"4  
} j_]#Ew\q  
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public static void log(int sMsg) -d'swx2aZ!  
{ l-/fFy)T  
System.err.println(sMsg); R3 Zg,YM  
} 3+:F2sjt  
} Bh<DqN  
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Ht`kmk;I)  
/* *z?
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**TestMethod.java P|U9f6^3  
*/ `I
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package NetFox; 2Q bCH}  
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public class TestMethod { <D}yqq@|  
|FED<  
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public TestMethod() =[_=y=G  
{ ///xx/weblogic60b2_win.exe qS|ns'[  
try{ UO~Xzx!e  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); /9QC$Z):<  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); /&>vhpZ}  
SiteFileFetch fileFetch = new SiteFileFetch(bean); X0FTD':f  
fileFetch.start(); 8%\0v?a5  
} p)&Yr  
catch(Exception e){e.printStackTrace ();} U7_1R0h  
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} Al}D~6MD  
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public static void main(String[] args) QZZt9rA;  
{ 5Z]]xR[  
new TestMethod(); \bXusLI!l  
} (JX 9c  
} /
^M|$JRI  
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