http断点续传简单实现（java)

/* o}!PQ#`M  
**SiteFileFetch.java Lr<cMK<  
*/ 4R*,VR.K  
package NetFox; #
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import java.io.*; fZ. ONq  
import java.net.*; *](iS  
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public class SiteFileFetch extends Thread { nrb Ok4Dz  
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SiteInfoBean siteInfoBean = null; //文件信息Bean M}Sv8D]I  
long[] nStartPos; //开始位置 AR=]=8  
long[] nEndPos; //结束位置 kP"9&R`E  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ceV}WN19l  
long nFileLength; //文件长度 VE24ToI?W"  
boolean bFirst = true; //是否第一次取文件 5m*,8]!-  
boolean bStop = false; //停止标志 =Uh$&m  
File tmpFile; //文件下载的临时信息 ^s=8!=A(  
DataOutputStream output; //输出到文件的输出流 RpF&\x>  
Ned
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） KSvE~h[#+  
public SiteFileFetch(SiteInfoBean bean) throws IOException ys~x$  
{ 7Wno':w8  
siteInfoBean = bean; pUTr!fR  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); OCUr{Nh  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); &vJH$R  
if(tmpFile.exists ()) :>*7=q=  
{ r,udO,Yi=c  
bFirst = false; ;fJ.8C  
read_nPos(); TN.rrop`#g  
} /\Ef%@  
else Fp:'MX  
{ @VBcJ{e,  
nStartPos = new long[bean.getNSplitter()]; "#]$r  
nEndPos = new long[bean.getNSplitter()]; :0ep(<|;  
} : 'c&,oLY  
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} *Uh!>Iv;  
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public void run() Q@niNDaW2  
{ zTp"AuNHN  
//获得文件长度 w@pPcZ>z/  
//分割文件 n ;Ei\\p!  
//实例FileSplitterFetch U17d>]ka  
//启动FileSplitterFetch线程 yr6V3],Tp  
//等待子线程返回 7"
##]m.
 
try{ ?CZdOl  
if(bFirst) H[gWGbPq7  
{ ?(PKeq6  
nFileLength = getFileSize(); g\U-VZ6;p  
if(nFileLength == -1) pI[uUu7O  
{ phK/  
System.err.println("File Length is not known!"); |zU-KGO&  
} XkqCZHYkS  
else if(nFileLength == -2) I*&8^r:A  
{ #QPjkR|\  
System.err.println("File is not access!"); qLCR] _*  
} @,}UWU  
else C+]I@Go'Tk  
{ -} +[  
for(int i=0;i<nStartPos.length;i++) S3#>9k;p  
{ XG?8s &  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 9ati`-y2  
} ~[ F`"  
for(int i=0;i<nEndPos.length-1;i++) )1z@
  
{ pw#-_  
nEndPos = nStartPos[i+1]; @L`jk+Y0vF  
} K'xV;r7Nt  
nEndPos[nEndPos.length-1] = nFileLength; S@Y39  
} 9$Y=orpWxr  
} fOHxtHM  
5N]
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pdMc}=K  
//启动子线程 @d_M@\r=j  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; KXrjqqXs  
for(int i=0;i<nStartPos.length;i++) Z,=1buSz_  
{ k!^{eOM  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), YQ}o?Q$z  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Fcx&hj1gQ  
nStartPos,nEndPos,i); .X&9Q9T=#  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^pS~Z~[d/  
fileSplitterFetch.start(); jo7\`#(Q  
}
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), LP-o8c  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); =AT."$r>  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", So6x"1B  
nEndPos = " + nFileLength); IgzQr>  
// fileSplitterFetch[nPos.length-1].start(); 3R/bz0 V>  
'R)Tn!6  
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//等待子线程结束 rjP/l6 ~'  
//int count = 0; 0_/[k*Re  
//是否结束while循环 lYIH/:T  
boolean breakWhile = false; `XKLU
 
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while(!bStop) e.%nRhSs3  
{ ^Pf WG*  
write_nPos(); y7{?Ip4[  
Utility.sleep(500); IBGrt^$M  
breakWhile = true; "
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for(int i=0;i<nStartPos.length;i++) xk5]^yDp  
{ #Y!a6h+  
if(!fileSplitterFetch.bDownOver) VUc%4U{Cti  
{ ("@!>|H  
breakWhile = false; }\f0 A-  
break; Mt$ *a  
} #Z#-Ht  
} x^ni1=kU  
if(breakWhile)
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break; V9v
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//count++; nTas~~
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//if(count>4) #_1`)VS  
// siteStop(); =I<R!ZSN  
} aXVFc5C\  

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System.err.println("文件下载结束！"); 9$t(&z=  
} ?< />Z)
  
catch(Exception e){e.printStackTrace ();} 3Vwh|1?  
} -=="<0c  
}k0_5S  
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//获得文件长度 mw!F{pw  
public long getFileSize() PCvWS.{  
{ 29rX%
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int nFileLength = -1; _$'ashF  
try{ /z!%d%"  
URL url = new URL(siteInfoBean.getSSiteURL()); }C:r9?T  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); E./2jCwI(Y  
httpConnection.setRequestProperty("User-Agent","NetFox"); H|*m$|$,  
[
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int responseCode=httpConnection.getResponseCode(); bOB\--:]  
if(responseCode>=400) uH]OEz\H'  
{ _w{Qtj~s|  
processErrorCode(responseCode); !VJoM,b8  
return -2; //-2 represent access is error Wzh
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} 1x)J[fyId  
.8R@2c`}Cs  
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String sHeader; w(/S?d  
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for(int i=1;;i++) YVU7wW,1  
{ =&]L00u.  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ^c<Ve'-
 
//Utility.log(in.readLine()); j^'go&p  
sHeader=httpConnection.getHeaderFieldKey(i); 8Wx=p#_  
if(sHeader!=null) %;_MGae  
{ UpG~[u)%@  
if(sHeader.equals("Content-Length")) \<' ?8ri#  
{ L#J1b!D&<6  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); fl(wV.Je|  
break; .3;;;K9a~]  
} uph(V  
} *T/']t  
else #4PN"o@  
break; X, n:,'  
} 6'/ #+,d'  
} _U(  
catch(IOException e){e.printStackTrace ();} y0#2m6u  
catch(Exception e){e.printStackTrace ();} [6fQ7uFMM8  
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Utility.log(nFileLength); V&5wRz+`W  
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8=l%5r^cq  
return nFileLength; cr3^6HB  
} ,prf;|e?  
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//保存下载信息（文件指针位置） 2ESo2  
private void write_nPos() ]DcFySyv  
{ r;{.%s7  
try{ RP"kC4~1  
output = new DataOutputStream(new FileOutputStream(tmpFile)); aOp\91  
output.writeInt(nStartPos.length); wT@og|M  
for(int i=0;i<nStartPos.length;i++) #mF"1QW  
{ K-4PI+qQ\  
// output.writeLong(nPos); _b 0&!l<  
output.writeLong(fileSplitterFetch.nStartPos); n S=W1zf  
output.writeLong(fileSplitterFetch.nEndPos); HfVZ~PP  
} +%'(!A?*`  
output.close(); _/|\aqF.  
} qm}@!z^  
catch(IOException e){e.printStackTrace ();} d0D]Q  
catch(Exception e){e.printStackTrace ();} ^!d3=}:
0  
} vN:Ng  
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)GpK@R]{  
//读取保存的下载信息（文件指针位置） d=(mw_-
?  
private void read_nPos() 3BI1fXT4=j  
{ s!J9|]o  
try{ R_C)  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); _f83-':W6  
int nCount = input.readInt(); ^('wy};  
nStartPos = new long[nCount]; (=0.inZ  
nEndPos = new long[nCount]; XSR 4iu  
for(int i=0;i<nStartPos.length;i++) ;l+Leex  
{ # d  
nStartPos = input.readLong(); .Mbz3;i0  
nEndPos = input.readLong(); l#o  ~W`  
} .A
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input.close(); S[gx{Bxiw  
} 7#XzrT]  
catch(IOException e){e.printStackTrace ();} qGo.WZ$  
catch(Exception e){e.printStackTrace ();} IxU/?Zm  
} 1zv'.uu.,  
:;}P*T*PU  
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private void processErrorCode(int nErrorCode) `?]k{ l1R  
{ la!~\wpa  
System.err.println("Error Code : " + nErrorCode); dPlV>IM$z  
} T)/eeZ$  
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U
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//停止文件下载 @"A4$`Xi3  
public void siteStop() oR'm2d^  
{ b6bHTH0  
bStop = true; (QEG4&9  
for(int i=0;i<nStartPos.length;i++) +7Gwg  
fileSplitterFetch.splitterStop(); )nkY_'BV  
L *wYx|  
J1k>07}
|  
} K-v#.e4  
} D*jM1w_`  
//负责部分文件的抓取 t.<i:#rj>l  
**FileSplitterFetch.java 4?kcv59  
*/ 9[4xFE?|  
package NetFox; Wr 4,YQM  
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>MZ/|`[M  
import java.io.*; ="+#W6bZT  
import java.net.*; z/-=%g >HA  
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public class FileSplitterFetch extends Thread { ch]IzdD  
#a#F,ZT  
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String sURL; //File URL 7CysfBF0g  
long nStartPos; //File Snippet Start Position -7ep{p-  
long nEndPos; //File Snippet End Position sJZiI}Xc  
int nThreadID; //Thread's ID >4TO=i  
boolean bDownOver = false; //Downing is over i-1op> Y  
boolean bStop = false; //Stop identical `5*}p#G  
FileAccessI fileAccessI = null; //File Access interface sHj/;  
3o*YzwRt  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException )0
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{ hN_]6,<\  
this.sURL = sURL; X|dlt{Gf   
this.nStartPos = nStart; yi[x}ffdE  
this.nEndPos = nEnd; Rq-ZL{LR7  
nThreadID = id; -"x$ZnHU  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 E.h*g8bXe  
} W/N7vAx X  
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public void run() KNl$3
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{ 0GLM(JmK  
while(nStartPos < nEndPos && !bStop) ~%oR[B7=|  
{ Eci\a]  
@7}W=HB  
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try{ kh<2BOV  
URL url = new URL(sURL); F4QVAOM]U  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :jf3HG  
httpConnection.setRequestProperty("User-Agent","NetFox"); &{:-]g\  
String sProperty = "bytes="+nStartPos+"-";  " bG2:  
httpConnection.setRequestProperty("RANGE",sProperty); u8^lB7!e/  
Utility.log(sProperty); `[A];]  

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InputStream input = httpConnection.getInputStream(); )J |6-C  
//logResponseHead(httpConnection); TeQV?ZQ#}  

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:RYTL'hes  
byte[] b = new byte[1024]; x`s>*^  
int nRead; 7<4qQ.deE  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) XW/o<[91  
{ crCJrN=  
nStartPos += fileAccessI.write(b,0,nRead); \8tsDG(1 '  
//if(nThreadID == 1) #yen8SskB  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 4-w{BZuS  
} UiWg<_<t  
=4!mAo}  
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Utility.log("Thread " + nThreadID + " is over!"); ]:;&1h3'7  
bDownOver = true; }H4RR}g  
//nPos = fileAccessI.write (b,0,nRead); %O<BfIZ  
} Cx"sw }  
catch(Exception e){e.printStackTrace ();} xno\s.H%]  
} =1! 'QUc  
} }Jw,>}  
]n~V!hl?A  
}JfjX'  
//打印回应的头信息 ?2a$*(  
public void logResponseHead(HttpURLConnection con) k)u[0}  
{ =Qq+4F)MD  
for(int i=1;;i++) BUFv|z+H  
{ |ZBw<f  
String header=con.getHeaderFieldKey(i); 1M-pr 8:6s  
if(header!=null) ^Cmyx
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); 6~{C.No}  
Utility.log(header+" : "+con.getHeaderField(header)); eyaNs{TV  
else QJNFA}*>  
break; }G=M2V<L  
} X]=t>
 
} ;<5q]/IHK  
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public void splitterStop() wr4:Go`  
{ NI5``BwpO  
bStop = true; fM}#ON>Z  
} +p^u^a  
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} 5x
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MDN--p08  
BVm0{*-[|  
/* DlT{`  
**FileAccess.java _wcNgFx  
*//文件访问(定位，写) BY*Q_Et  
package NetFox; E4!Fupkpf  
import java.io.*; \jA~9  
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public class FileAccessI implements Serializable{ tgaO!{9I?  
u>$t'  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 X8|EHb<  
RandomAccessFile oSavedFile; `6YN3XS  
long nPos; K^$=dLp  
':W[
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public FileAccessI() throws IOException F?cK-.  
{ DMS!a$4  
this("",0); *H122njH+T  
} :4s1CC+@\  
_
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1}37Q&2  
public FileAccessI(String sName,long nPos) throws IOException fh{`Mz,o  
{ q;U,s)Uz^  
oSavedFile = new RandomAccessFile(sName,"rw"); 9kojLqCT  
this.nPos = nPos; 7KPwQ?SjT  
oSavedFile.seek(nPos); GL JMP^p  
} &{RDM~  
G j1_!.T  
ca}2TT&t  
public synchronized int write(byte[] b,int nStart,int nLen) -+5>|N#  
{ {t!!Uz 7  
int n = -1; fV:83|eQ  
try{ b\ PgVBf9  
oSavedFile.write(b,nStart,nLen); +3`alHUK  
n = nLen; [V!tVDs&'o  
} dd["dBIZ '  
catch(IOException e) 2Hdu:"j  
{ ]d`VT)~vje  
e.printStackTrace (); *dF>_F  
} OH"XrCX7n  
e%6QTg5#  
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return n; i&k7-<  
} 6Iw\c  
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} qVPeB,kIz  
r
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/* RL<c>PY  
**SiteInfoBean.java
Ha ]YJ}  
*/ 5?L<N:;J_  
package NetFox; KU;9}!#  
d1kJRJ   
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public class SiteInfoBean { 0g\(+Qg^  
[r-p]"R  
1sCR4L:+  
private String sSiteURL; //Site's URL <ih[TtZ  
private String sFilePath; //Saved File's Path -![|}p
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private String sFileName; //Saved File's Name +*^H#|!  
private int nSplitter; //Count of Splited Downloading File }-fl$j?9E  
" Jr-J#gg  
&[SC|=U'M  
public SiteInfoBean() kN>!2UfNS  
{//nSplitter的缺省值为5 Wl Sm  
//default value of nSplitter is 5 
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this("","","",5); ZC}QId  
} T)}) pt!V  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 5-G@L?~Vw  
{ j7c3(*Pl  
sSiteURL= sURL; wPl%20t  
sFilePath = sPath; pmilrZmm]  
sFileName = sName; \;-|-8Q  
this.nSplitter = nSpiltter; 4X$Qu6#i  
s@DLt+ O5  
iX\X>W$P  
} d| {r5[&  
g*"P:n71  
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public String getSSiteURL() Dxxm="FQZ  
{ m6djeOl  
return sSiteURL; K@#L)VT!  
} )ANmIwmC#  
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public void setSSiteURL(String value) `@ FYkH  
{ jSAjcLR  
sSiteURL = value; s0_nLbWwO  
} aATA9V  
9E tz[`|  
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public String getSFilePath() ((I%'  
{ N!|wo:  
return sFilePath; 2Gdd*=4z  
} n}V_,:Z  
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public void setSFilePath(String value) rt|7h>RQ  
{ ^KELKv,_  
sFilePath = value; &w~
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} FE{FGMq  
LDg?'y;2  
/SrAW`;"  
public String getSFileName() J'2X&2  
{ 6DWgl$[[  
return sFileName; [h:T*(R?  
} p"Z-6m~  
eN~=*Mn(za  
3{h_&Gbo'D  
public void setSFileName(String value) !L8#@BjU  
{ $pudoAO  
sFileName = value; +KEWP\r  
} )tpL#J  
i@BtM9:  
U3:j'Su4H?  
public int getNSplitter() nQ L@hc  
{ S[T8T|_  
return nSplitter; Qdp)cT  
} B~du-Z22IZ  
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public void setNSplitter(int nCount) I0RvnMw  
{ BRYHX.}h\A  
nSplitter = nCount; ^KE%C;u  
} +t:0SRSt  
} (@}!0[[^  
{91nL'-'  
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/* 0<B$#8  
**Utility.java tdaL/rRe  
*/ y#$CMf -q^  
package NetFox; /^
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s|B3~Q]  
public class Utility { &l[$*<P5V  
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public Utility() !&Pui{F  
{ D#/Bx[  
[ps*uva  
N{~YJ$!8  
} BI}Cg{^km  
3 SGDy]  
//线程睡眠 HOh!Xcu  
public static void sleep(int nSecond) 14'45  
{ .k \@zQ|Ta  
try{ u=_mvN  
Thread.sleep(nSecond); t@Nyr&|D  
} Dl8;$~  
catch(Exception e) M {Q;:  
{ wIBO ^w\
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e.printStackTrace (); 8Dm%@*B^b  
} K:Q<CQ2  
} iRi-cQVy  
[R7Y}k:9U  
//日志 s&!a  
public static void log(String sMsg) '-/xyAzS  
{ -8rjgB~."/  
System.err.println(sMsg); aCLqk'  
} A6iq[b]  
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fe#\TNeQJ[  
public static void log(int sMsg) D+7Rz_=  
{ q=qcm`ce  
System.err.println(sMsg); qc~iQSI  
} U2~kJ  
} ?#YE`]  
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/* y {<9]'  
**TestMethod.java M_w<m  
*/ (41|'eB\\  
package NetFox; ^UhBH@ti  
JO"<{ngsQ  
DXK}-4"\  
public class TestMethod { JOim3(5?s  
A:9?ZI/X  
fn6J*[`  
public TestMethod() }t1a*z  
{ ///xx/weblogic60b2_win.exe Z} r*K%  
try{ 2oRg 2R}  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); B\:%ufd ~  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); )sp4Ie  
SiteFileFetch fileFetch = new SiteFileFetch(bean); h_IDO%  
fileFetch.start(); ""QP%  
} n`&U~s8w  
catch(Exception e){e.printStackTrace ();} x6ARzH\  
2q4<
t:!  
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} /mu*-,aeX  
Jy
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public static void main(String[] args) 0aa&m[Mk  
{ (%W&4a1di  
new TestMethod(); ^7KH _t8
 
} g5QZ0Qk
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} x&T[*i  
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