http断点续传简单实现（java)

/* %K\B)HR
 
**SiteFileFetch.java e&ZTRgYdi  
*/ p8.JJt^  
package NetFox; a|t{1]^w`  
import java.io.*; 0VJHE~Bgi  
import java.net.*; >{Mv+  
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public class SiteFileFetch extends Thread { G){+.X4g3  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ESIJ QM-[+  
long[] nStartPos; //开始位置 H[pvC=O=  
long[] nEndPos; //结束位置 NzhWGr_x'  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 2'W#x  
long nFileLength; //文件长度 q%A>q;l:  
boolean bFirst = true; //是否第一次取文件 $1s>efP-  
boolean bStop = false; //停止标志 Q8l vwip  
File tmpFile; //文件下载的临时信息 gxI/MD~!>  
DataOutputStream output; //输出到文件的输出流 c(8>oeKyD  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） `]19}GK~xo  
public SiteFileFetch(SiteInfoBean bean) throws IOException [Ax:gj  
{ n3U| d+  
siteInfoBean = bean;  4J=6U&b  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); JCZ&TK  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 69ycP(  
if(tmpFile.exists ()) 9w&CHg7D i  
{ }>,%El/  
bFirst = false; VpbJe@*D  
read_nPos(); bqF?!t<B  
} 4C:dkaDq]  
else {4[
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{ +",`Mb  
nStartPos = new long[bean.getNSplitter()]; 16z WmJH  
nEndPos = new long[bean.getNSplitter()]; 9"B;o  
} U~7{q >  
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} jt3W.^6HO  
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public void run() #t# S(A9)  
{ 0T$`;~  
//获得文件长度 \b)P4aL  
//分割文件 q9^.f9-  
//实例FileSplitterFetch <0l:B;
3  
//启动FileSplitterFetch线程 8)
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//等待子线程返回 U&$I!80.  
try{ <A\g*ld  
if(bFirst) P6v@ Sn  
{ b*nI0/cbR.  
nFileLength = getFileSize(); I;$tBgOWq  
if(nFileLength == -1) !+UXu]kA  
{ eIPk$j{e  
System.err.println("File Length is not known!"); x<d ew  
} :}SR{}]yXs  
else if(nFileLength == -2) %hBw)3;l  
{ %$_?%X0=t  
System.err.println("File is not access!"); vKkvB;F41  
}
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else rX`fjS*C  
{ ZiH4s|  
for(int i=0;i<nStartPos.length;i++) bhZ5-wo4%  
{ |NjyO>@Pa  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); wlP% U  
} e6T?2`5P  
for(int i=0;i<nEndPos.length-1;i++) lL'K1%{+ \  
{ ^ilgd  
nEndPos = nStartPos[i+1]; h{)`W ]~  
}
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nEndPos[nEndPos.length-1] = nFileLength; &(x>J:b  
} sJg3WN  
} TQ {8 ee{  
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4 T/ ~erc  
//启动子线程 yN
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; , d4i0;2}+  
for(int i=0;i<nStartPos.length;i++) !E *IktAI  
{ |IWm:[H3  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), WCI'Kh 
 
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), PCKxo;bD  
nStartPos,nEndPos,i); fjQIuM  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); o3OJI_ v&  
fileSplitterFetch.start(); "KY]2v.  
} bG)6p05Oa  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), <(~geN  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); H[r64~Sth  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $T2zs$  
nEndPos = " + nFileLength); I=K<%.  
// fileSplitterFetch[nPos.length-1].start(); MY&?*pV)  
t{ridA}  
!6s]p%{V  
//等待子线程结束 !<>`G0  
//int count = 0; qMBEJ<o  
//是否结束while循环 *b1NVN$  
boolean breakWhile = false; B8V85R  
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while(!bStop) Yd~Tzh  
{ YE@!`!`d:  
write_nPos(); %U97{y  
Utility.sleep(500); Fi+,omB&  
breakWhile = true; E{}eYU
 
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for(int i=0;i<nStartPos.length;i++) >PygUY d  
{ UWBR5  
if(!fileSplitterFetch.bDownOver) j0e1CSE  
{ 6rAenK-%  
breakWhile = false; Y3luU&'  
break; w6k^|."  
} mw=keY9]  
} -.vNb!=  
if(breakWhile) -EU~ %/=m+  
break; nyd'79~>G  
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b=Q%Jxz?  
//count++; MCfDR#a  
//if(count>4)
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// siteStop(); 55x.Q  
} k%cT38V*  
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System.err.println("文件下载结束！"); &R}2/Mt  
} /vFdhh  
catch(Exception e){e.printStackTrace ();} s.@DI|Gnf  
} Cx`?}A\%  
Gh{vExH@5(  
> bSQ}kXe  
//获得文件长度 X57\sggK  
public long getFileSize() "1$hfs  
{ p\,PY  
int nFileLength = -1; QEq>zuz5;  
try{ Y3f2RdGl  
URL url = new URL(siteInfoBean.getSSiteURL()); Q<Th*t  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Hh<}~s  
httpConnection.setRequestProperty("User-Agent","NetFox"); G]fx3=  
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int responseCode=httpConnection.getResponseCode(); k%ckV`y  
if(responseCode>=400) QPwUW  
{ e_CgZ  
processErrorCode(responseCode); y+a]?`2  
return -2; //-2 represent access is error ;jpsH?3g
 
} .AHww7  
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String sHeader; Y-:{a1/RKo  
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for(int i=1;;i++) t{ScK
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{ ]1n =O"vE  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); mE_?E&T`|  
//Utility.log(in.readLine()); ^T/d34A;SP  
sHeader=httpConnection.getHeaderFieldKey(i); w#`E;fN'  
if(sHeader!=null) {3=]cLtt  
{ IH'&W  
if(sHeader.equals("Content-Length")) FFqqAT5  
{ \*$''`b)j  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); #+Cu&l  
break; ,Tc598D  
} dJd(m&.|N  
} Qa=v }d-O  
else gS4@3BOw&.  
break; {%3sj"suB  
} f\gN+4)  
} `G^MTDp?L+  
catch(IOException e){e.printStackTrace ();} VE5M}kDCZ  
catch(Exception e){e.printStackTrace ();} '}NQ`\k  
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Utility.log(nFileLength); P_ x9:3  
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return nFileLength; x0_$,Tz@  
} }*I:0"WH  
0 lsX~d'W  
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//保存下载信息（文件指针位置） \"@BZ.y
 
private void write_nPos() v9s/!<j  
{ 7ClN-/4  
try{ BiUbg6T.G  
output = new DataOutputStream(new FileOutputStream(tmpFile)); @'{m-?*  
output.writeInt(nStartPos.length); q}mQm'  
for(int i=0;i<nStartPos.length;i++) U(cV#@Y  
{ A~Ov(  
// output.writeLong(nPos); Ov=^}T4zl  
output.writeLong(fileSplitterFetch.nStartPos); "]C$"JR  
output.writeLong(fileSplitterFetch.nEndPos); ]%VR Nm
 
} 1zUo.Tg0  
output.close(); k&PxhDf  
} qXJBLIG  
catch(IOException e){e.printStackTrace ();} &}G2;O}3  
catch(Exception e){e.printStackTrace ();} )a

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} 2pEr s|r  
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//读取保存的下载信息（文件指针位置） ki[Yu+';}  
private void read_nPos() 9'|NF<  
{ =N%;HfUD  
try{ ?tLBEoUmKT  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); y9OxPq.Cy  
int nCount = input.readInt(); {@c)!%2$  
nStartPos = new long[nCount]; xi2!__  
nEndPos = new long[nCount]; hI{M?LQd  
for(int i=0;i<nStartPos.length;i++) i?&g
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{ H#luG_)  
nStartPos = input.readLong(); +84JvOkWi  
nEndPos = input.readLong(); |i7j}i  
} b xT
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input.close(); IPE2t  
} #PpmR_IX  
catch(IOException e){e.printStackTrace ();} 2.zx  
catch(Exception e){e.printStackTrace ();} QFm~wv8:  
} q;p:)Q"  
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private void processErrorCode(int nErrorCode) { ke}W  
{ pLvvv#Y  
System.err.println("Error Code : " + nErrorCode); D/1f>sl  
} nmn 8Y V1  
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//停止文件下载 oyS43/."  
public void siteStop() G/:;Qig  
{ A[F tPk{k  
bStop = true; `is."]%f  
for(int i=0;i<nStartPos.length;i++) !z7j.u`Y  
fileSplitterFetch.splitterStop(); \/Z?QBFvz  
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M
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} 4#o
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} ppjS|l*`  
//负责部分文件的抓取 4]F:QS% x  
**FileSplitterFetch.java #&A)%Qbg  
*/ %B&y^mZv*\  
package NetFox; U=4tJb
 
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import java.io.*; Q,# )  
import java.net.*; c5& _'&  
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public class FileSplitterFetch extends Thread { s3sAw~++  
u/5^N^@^  
b42"Y,sbB  
String sURL; //File URL h#ogL-UU  
long nStartPos; //File Snippet Start Position mlsM;Ad2  
long nEndPos; //File Snippet End Position &> Myf@  
int nThreadID; //Thread's ID tCFXb6Cz  
boolean bDownOver = false; //Downing is over Lb2bzZbhx  
boolean bStop = false; //Stop identical K
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FileAccessI fileAccessI = null; //File Access interface =}6yMR!4R<  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException D\}A{I92F4  
{ TmZ% ;TN  
this.sURL = sURL; {_GhS
%  
this.nStartPos = nStart; UQmdm$.  
this.nEndPos = nEnd; bT^6AtsJ  
nThreadID = id; b'1n1L  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 "Zo<$p3]  
} h/7m.p]  
^h}xFiAV#  
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public void run() dWhki|c  
{ 9"5J-a'  
while(nStartPos < nEndPos && !bStop) ev}lb+pr)_  
{ hx4X#_)v  
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try{ 1$&(ei]*:  
URL url = new URL(sURL); sYQ=nL  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); vhA4ol  
httpConnection.setRequestProperty("User-Agent","NetFox"); 0}a="`p#<  
String sProperty = "bytes="+nStartPos+"-"; >h?!6L- d  
httpConnection.setRequestProperty("RANGE",sProperty); S${n:e0\  
Utility.log(sProperty); ){u/v[O9"  
+j*hbG=  
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InputStream input = httpConnection.getInputStream(); O$=[m9
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//logResponseHead(httpConnection); i(hI\hD  
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byte[] b = new byte[1024]; hG~TqH^}B  
int nRead; gLyXe,Jp  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) `1AVw]k  
{ oa4{s&db-  
nStartPos += fileAccessI.write(b,0,nRead); \e89 >m  
//if(nThreadID == 1) bi^[Eh  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); rHzwSR@}1  
} &!|'EW  
P4&3jQ[o  
: MfY8P)  
Utility.log("Thread " + nThreadID + " is over!"); O] T'\6w  
bDownOver = true; 4CUzp.S`h  
//nPos = fileAccessI.write (b,0,nRead); 4'Svio  
} &:K!$W  
catch(Exception e){e.printStackTrace ();} 2U;6sn*e  
} =UGyZV:z5  
} 4<j)1i=A  
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//打印回应的头信息 l70a&[W  
public void logResponseHead(HttpURLConnection con) MLbmz\8a  
{ xSnkv,my<  
for(int i=1;;i++)
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{ p\A!"KC  
String header=con.getHeaderFieldKey(i); ~F gxhK2+  
if(header!=null) Ez\TwK  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); k}MmgaT:5]  
Utility.log(header+" : "+con.getHeaderField(header)); >iZ"#1ZL2O  
else [{}Hk%wlX  
break; z|pC*1A\  
} s7"NK"  
} ]Alv5?E60  
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public void splitterStop() I&m C  
{ MBeubS  
bStop = true; Wu}84W"!.V  
} sbeS9vE  
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} %QYH]DR  
{WYJQKs8  
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/* })?t:zX#*  
**FileAccess.java DJ zJ$Q  
*//文件访问(定位，写) /A
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package NetFox; l2Gtw*i_I  
import java.io.*; -a=RCzX]  
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public class FileAccessI implements Serializable{ Q%_QT0H9Kz  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 DlMT<ld  
RandomAccessFile oSavedFile; | e?:Uq  
long nPos; *Y:;fl +v  
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public FileAccessI() throws IOException W(gOidKKz  
{ >8v4fk IK  
this("",0); 0~/'c0Ho  
} 3A`|$So  
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b.N$eJlQ&  
public FileAccessI(String sName,long nPos) throws IOException [}mx4i  
{ rEoMj)~\4&  
oSavedFile = new RandomAccessFile(sName,"rw"); bgk+PQ#S-  
this.nPos = nPos; PLb[U(
~
 
oSavedFile.seek(nPos); j[ fE^&  
} Q\QSnMM&]  
EE{]EW(  
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public synchronized int write(byte[] b,int nStart,int nLen) *eF'<._[U  
{ V_x8 Q+~?  
int n = -1; y#B4m`9  
try{ ~x-"?K  
oSavedFile.write(b,nStart,nLen); ++gWyzD  
n = nLen;
762c`aP_(  
} _ SuW86  
catch(IOException e) ;h7W(NO~z  
{ hI$IBf>  
e.printStackTrace (); -eQ>3x&3r  
} *!m
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{  
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return n; [C0"vOTUb  
} 
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} WA?We7m$  
_{ Np_(g  
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/* ZL7#44  
**SiteInfoBean.java !*\J4bJe  
*/ >d9b"T  
package NetFox; u6t%*''  
l^cz&k=+  
9OS~;9YR  
public class SiteInfoBean { Hz>_tA"^T  
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private String sSiteURL; //Site's URL y0R9[;b07  
private String sFilePath; //Saved File's Path * YR>u@  
private String sFileName; //Saved File's Name %7S{g  
private int nSplitter; //Count of Splited Downloading File yADX^r(  
u[<ij  
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public SiteInfoBean() Y(/y,bJ?jp  
{//nSplitter的缺省值为5 EJid@  
//default value of nSplitter is 5 4}r.g0L  
this("","","",5); cHAq[Ebp2!  
} N|3a(mtiZ'  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) wqasI@vyu  
{ &-c{  
sSiteURL= sURL; O4g2s8k  
sFilePath = sPath; ww5UQs2sn  
sFileName = sName; sDZ<XA  
this.nSplitter = nSpiltter; "Q.KBX v/  
n|'}W+  
q&nEodv>+  
} Ywo
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public String getSSiteURL() $lAQcG&Q  
{ #ULzh&yO  
return sSiteURL;
b(Nxk2uv  
} peZ'sZ6  
( d1ho=  
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public void setSSiteURL(String value) xFj<KvV[  
{ XE`u  
sSiteURL = value; l|S_10x5  
} }08Sv=XM  
%%{f-\-7Ig  
(,j~s{  
public String getSFilePath() hbSXa'
 
{ h @2.D|c)g  
return sFilePath; !E~czC\p6  
} K9_@[}Ge  
w gkY\Q  
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public void setSFilePath(String value) mum4Uj  
{ cq4sgQ?sW  
sFilePath = value; b~C^cM  
} xxZO{_q  
X
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9`Y\`F#}q  
public String getSFileName() Z5Tu*u=  
{ G4,.kK  
return sFileName; AmX ~KK  
} fU>4Ip1?y/  
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bE%*ZB  
public void setSFileName(String value) 1UN$eb7  
{ +(m*??TAV  
sFileName = value; D9r4oRkP*  
} >l=;6QL  
| E\u  
vxk~(3]<)  
public int getNSplitter() C[[:/X(c  
{ 0I}c|V'P  
return nSplitter; (L,>P`CR6  
} s(r1q$5  
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public void setNSplitter(int nCount) ZJOO*S  
{ )P#xny2  
nSplitter = nCount; Ih%LKFT  
} ,H@ x.  
} |6w{%xC?"  
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/* . sv uXB  
**Utility.java @ 5V3I^  
*/ ;edt["Eu  
package NetFox; 8.tp#x,A  
L[. )!c8k  
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public class Utility { J8@7 5p9  
`e}6/~R`  
RX,c4;  
public Utility() 13MB1n  
{ _{mG\*q  
d$PQb9Q+f  
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} Vb/XT{T;b  

a!mdL|eA@  
//线程睡眠 ,Ad{k   
public static void sleep(int nSecond) ,H5o/qNU`{  
{ 9@8)ZHf  
try{ g*$yUt  
Thread.sleep(nSecond); Vee;&  
} BF(Kaf;<t.  
catch(Exception e) vve[.Lud'  
{ gFw-P#t  
e.printStackTrace (); m8z414o  
} xj.)iegQ  
} ~uweBp~O  
{AO`[  
//日志 ]MRQcqbpqL  
public static void log(String sMsg) J7$JW3O  
{ ~w}Zv0  
System.err.println(sMsg); ZO!)G   
} 'H)l~L  
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public static void log(int sMsg) )jaNFJ 3  
{ O<`\9  
System.err.println(sMsg); ARa9Ia{@  
} m;m4/z3U  
}  u9,ZY>  
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uJ>_ 2  
/* =ms o1  
**TestMethod.java ^|h})OHV  
*/
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package NetFox; he1OLk  
q)KLf\  

rQ$Jk[Y  
public class TestMethod { zoO9N oUHW  
U{~R39  
pxO?:B  
public TestMethod() sXm,y$\m  
{ ///xx/weblogic60b2_win.exe qaN%&K9F8  
try{ pm~uWXqxr=  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); xDTDfhA  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); d&[.=M\E8  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Ex3V[v+D(  
fileFetch.start(); tx01*2]pX  
} RB `
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catch(Exception e){e.printStackTrace ();} 7s-ZRb[)1  
]U,f}T"e  
Kh;jiK !  
} D_4UM#Tw  
dr8`;$;G*  
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public static void main(String[] args) ~}F$1;t0  
{ qOd*9AS'|M  
new TestMethod(); ,c_NXC^X?  
} pX/,s#dY>  
} X1{U''$ K  
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