http断点续传简单实现（java)

/* ){PL6|5x  
**SiteFileFetch.java lAxbF  
*/ 0 s
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package NetFox; r pv`%  
import java.io.*; gRk%ObJGqm  
import java.net.*; |-W7n'n  
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public class SiteFileFetch extends Thread { \Qh{uk[  
 f:_\S  
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SiteInfoBean siteInfoBean = null; //文件信息Bean B}%B4&Ij  
long[] nStartPos; //开始位置 =Mb1)^m  
long[] nEndPos; //结束位置 iG\]  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 dA`.  
long nFileLength; //文件长度 ]pZxbs&Vb  
boolean bFirst = true; //是否第一次取文件 ^=H. .pr  
boolean bStop = false; //停止标志 SxHj3,`#C  
File tmpFile; //文件下载的临时信息 {c'2{`px 5  
DataOutputStream output; //输出到文件的输出流 CMm:Vea  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） NDJIaX:]  
public SiteFileFetch(SiteInfoBean bean) throws IOException c
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{ pohA??t2:  
siteInfoBean = bean; BrdHTk= Vy  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Ye'=F  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); f__r" N  
if(tmpFile.exists ()) dPdodjSu,!  
{
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bFirst = false; I.f)rMl+h  
read_nPos(); +J^-B}v  
} z$VA]tI(  
else yEnurq%J  
{ 5Iv3B|u  
nStartPos = new long[bean.getNSplitter()]; X*'tJN$  
nEndPos = new long[bean.getNSplitter()]; E|(T(4;  
} Oie0cz:>:  
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} eY)JuJ?  
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public void run() ]wH,534  
{ K0|8h!WF+  
//获得文件长度 ?R 4sH  
//分割文件 =*VKp{5=  
//实例FileSplitterFetch p[Pa(a,B7  
//启动FileSplitterFetch线程 N3D{t\hg  
//等待子线程返回 )jM' x&Vg  
try{ X=i^[?C  
if(bFirst) e/pZLj]M  
{ YEL,TU  
nFileLength = getFileSize(); PdUlwT?8C  
if(nFileLength == -1) (v11;kdJB  
{ OJ (ho&((  
System.err.println("File Length is not known!"); r#ISIgJXG  
} p;[">["  
else if(nFileLength == -2) xWwQm'I2}  
{ 7oj ^(R,  
System.err.println("File is not access!"); G:W4<w  
} u&q RK>wLa  
else %h)6o99{wF  
{ <oweLRt  
for(int i=0;i<nStartPos.length;i++) BT|5"b}  
{ Q>jx`68'KI  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ~uF%*  
} K.y2 $b/  
for(int i=0;i<nEndPos.length-1;i++) C+,JLK  
{ pvCf4pf~  
nEndPos = nStartPos[i+1]; T6gugDQ~.  
} PGaB U3  
nEndPos[nEndPos.length-1] = nFileLength; zYCrfr  
} :[;]6;
 
} F/MzrK\':m  
&+@~;p5F  
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//启动子线程 v8 Q/DJ~  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; > 3<P^-9L  
for(int i=0;i<nStartPos.length;i++) ,/d R  
{ CdxEY  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), W'3&\}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), [I4:R_\  
nStartPos,nEndPos,i); [(Z sQK  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos);
5H (CP  
fileSplitterFetch.start(); dKs^Dq  
} C$9+p@G6  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,QDS_u$xi&  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Q_ zGs6  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", *h+@a  
nEndPos = " + nFileLength); Pm2T
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// fileSplitterFetch[nPos.length-1].start(); j"F
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W
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<78]OZ] Z  
//等待子线程结束 X67.%>#3  
//int count = 0; :lF[k`S T  
//是否结束while循环 /i$-ws-  
boolean breakWhile = false; _cz&f%qr  
f.V
1  
I) mP?  
while(!bStop) N|Cx";,|FZ  
{ ds@w=~  
write_nPos(); ~VNN  
Utility.sleep(500);  tCT-cs

 
breakWhile = true; -P|EV|8=  
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for(int i=0;i<nStartPos.length;i++) Y)?dq(  
{ Z3:M%)e_u$  
if(!fileSplitterFetch.bDownOver) I6bekOvP  
{ <SiD m-=E  
breakWhile = false; 7@[3]c<=  
break; bjgf8427I  
} %9|}H [x  
} p&B c<+3e  
if(breakWhile) (C<~:Y?%  
break; aE[>^~Lv}  
nZ;h&N-_-  
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//count++; A=Au>"nAA  
//if(count>4) qT`sPEs;V  
// siteStop(); K<@gU\-!  
} #St=%!  
;aZ$qgN*Y  
DP2 ^(d<  
System.err.println("文件下载结束！"); m$T?~oo  
} it=4cHT  
catch(Exception e){e.printStackTrace ();} zdDn. vG  
} aq~g54  
'r KDw06/  
g.AMCM?z
 
//获得文件长度 wzX 1!?  
public long getFileSize() RX-qL,dc  
{ l,FK\  
int nFileLength = -1; dXAKk[uf  
try{ :HSqa9>wa  
URL url = new URL(siteInfoBean.getSSiteURL()); BMw_F)hTO  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); sE*A,z?  
httpConnection.setRequestProperty("User-Agent","NetFox"); ENlqoj1  
X#l]%
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int responseCode=httpConnection.getResponseCode(); Q'f!392|  
if(responseCode>=400) 0\G`AO;D  
{ V=<OV]0  
processErrorCode(responseCode); Q>\y%&df  
return -2; //-2 represent access is error HGuY-f  
} i^c  
!olvP*c"  
7X
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String sHeader; N3P!<J/tc  
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for(int i=1;;i++) W"9?D  
{
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); IUX~dO  
//Utility.log(in.readLine()); Vp =  
sHeader=httpConnection.getHeaderFieldKey(i); Fs^d-I  
if(sHeader!=null) kV@*5yc?R  
{ \;0J6LBc  
if(sHeader.equals("Content-Length")) ?Ji.bnfK  
{ I(6k.PQ  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ~z
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break; :
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} %B^nQbNDM  
} <VP@#  
else U#oe8(?#  
break; R} nY8zE  
} qXPT1%+)y  
} S~WsGLF s  
catch(IOException e){e.printStackTrace ();} P0m;AqS#R  
catch(Exception e){e.printStackTrace ();} ]h0Fv-[A  
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Utility.log(nFileLength); qaBjV6loy  
&KfRZ`9H  
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return nFileLength; 1tvgM !.  
} 0s
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}s;W{Q  
//保存下载信息（文件指针位置） ny:c&XS  
private void write_nPos() Lp\89tB>  
{ ".&x`C  
try{ vkE[Ur>  
output = new DataOutputStream(new FileOutputStream(tmpFile)); qzv$E
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output.writeInt(nStartPos.length); g%z?O[CN  
for(int i=0;i<nStartPos.length;i++) uq;,h46ki  
{ H \$04vkR  
// output.writeLong(nPos); 76[
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output.writeLong(fileSplitterFetch.nStartPos); 9XGzQ45R  
output.writeLong(fileSplitterFetch.nEndPos); F{*S}&q*)o  
} &*TwEN^h  
output.close(); #4h_(Y  
} !:Lb^C;/  
catch(IOException e){e.printStackTrace ();} 1x+YgL5  
catch(Exception e){e.printStackTrace ();} :0BaEqX  
} 1Yt;1k'  
(>m3WI$d  
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//读取保存的下载信息（文件指针位置） $KL5Z#K  
private void read_nPos() 8" Z!: =A  
{ csTX',c  
try{ OZ?4"1$.t  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); |;q*Zy(  
int nCount = input.readInt(); 4]$cf:  
nStartPos = new long[nCount]; .+XGbs]kCi  
nEndPos = new long[nCount]; A(y^1Nm  
for(int i=0;i<nStartPos.length;i++) l 6wX18~XJ  
{ \LB =_W$  
nStartPos = input.readLong(); %
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nEndPos = input.readLong(); jREj]V>  
} 9NwA5TP9_  
input.close(); ZVotIQ/Q'  
} B 95}_q  
catch(IOException e){e.printStackTrace ();} htbN7B(  
catch(Exception e){e.printStackTrace ();} WXj}gL`  
} }?B=R#5  
\nV|Y=5  
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private void processErrorCode(int nErrorCode) %-@`|  
{ (j-[m\wF  
System.err.println("Error Code : " + nErrorCode); L{$ZL&  
} C)> ])'S  
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>8;Co]::kx  
//停止文件下载 2BOe,giy  
public void siteStop() T*>n a8W  
{ _H|c_  
bStop = true; 8:,E=swe  
for(int i=0;i<nStartPos.length;i++) -A}*Aa'\  
fileSplitterFetch.splitterStop(); 8XwAKN:f  
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} &F"Mkyf  
} yTw0\yiO  
//负责部分文件的抓取 po_||NIY  
**FileSplitterFetch.java  =%AFn9q  
*/ 0 1[LPN  
package NetFox; _xign
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import java.io.*; 07-S%L7Z  
import java.net.*; <^VZ4$j  
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public class FileSplitterFetch extends Thread { 03L"W^gc  
-!(  
!]Z> T5$  
String sURL; //File URL K^AX=B  
long nStartPos; //File Snippet Start Position "iE9X.6NMu  
long nEndPos; //File Snippet End Position -bSe=09;S|  
int nThreadID; //Thread's ID 06 gE;iT  
boolean bDownOver = false; //Downing is over 2X2,(D!  
boolean bStop = false; //Stop identical GP ;c$pC  
FileAccessI fileAccessI = null; //File Access interface rAD5n,M]  
QLo^6S5!  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException +]Of f^s  
{ ]B0>r^  
this.sURL = sURL; [wl:"rm  
this.nStartPos = nStart; .['@:}$1  
this.nEndPos = nEnd; Ltpd:c  
nThreadID = id; C,C%1  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 qOz,iR?}  
} $DC*&hqpt  
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public void run() x Yr-,$/  
{ 
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while(nStartPos < nEndPos && !bStop) J) v~  
{ (A?{6  
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try{ w3:WvA5jt  
URL url = new URL(sURL); Q17"hO>kC  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Z
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httpConnection.setRequestProperty("User-Agent","NetFox"); &|P@$O>  
String sProperty = "bytes="+nStartPos+"-"; N]: "3?%  
httpConnection.setRequestProperty("RANGE",sProperty); ]@1YgV  
Utility.log(sProperty); XhFa9RC  
8%JxXtWW`  

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InputStream input = httpConnection.getInputStream(); o#E 3{zM  
//logResponseHead(httpConnection); mnL \c'  
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byte[] b = new byte[1024]; HyXw^ +tsj  
int nRead; !cw<C*
 
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0Mt2Rg}  
{ B{!)GZ(}  
nStartPos += fileAccessI.write(b,0,nRead); ~6@zXHAS  
//if(nThreadID == 1) jD3,z*  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ~\/>b}^uf'  
} 0CI?[R\  
}gyJaMA  
VB*N;bM^  
Utility.log("Thread " + nThreadID + " is over!"); z h0m3|9O  
bDownOver = true; exV6&bdu  
//nPos = fileAccessI.write (b,0,nRead); wXDF7tJh  
} 'P}"ZHW  
catch(Exception e){e.printStackTrace ();} +V1EqC*  
} W^0F(9~!(  
} >b,o yM  
dN;kYWRK  
NUb^!E"  
//打印回应的头信息 }uWJ  
public void logResponseHead(HttpURLConnection con) wNDLN`,^H  
{ 9}`O*A=KC  
for(int i=1;;i++) &KgR;.R^J  
{ nul?5{z@  
String header=con.getHeaderFieldKey(i); _~_04p  
if(header!=null) NKLGbH  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); dra'1E  
Utility.log(header+" : "+con.getHeaderField(header)); ];6c/#2x  
else rwFR5  
break; [y}/QPR  
} ^G=wRtS  
} *103  
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~j3B'  
public void splitterStop() Yqm
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{ u#%Ig3  
bStop = true; |8&AsQd  
} p+;Re2Uyg  
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} m(nlu  

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 ?1r@r  
/* 7GfgW02  
**FileAccess.java  wxsJB2  
*//文件访问(定位，写) COFs?L.`  
package NetFox; ]l+Bg;F#V  
import java.io.*; \l{*1lQ`  
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= Ii@-C  
public class FileAccessI implements Serializable{ i2.y)K)  
2iI"|k9M  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ,Ng3!2&$e  
RandomAccessFile oSavedFile; K%qunjv  
long nPos; {d}-SoxH  
I"Ji_
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public FileAccessI() throws IOException ' F`*(\#  
{ 84b;G4K  
this("",0); 3{Ze>yFE  
} NUH;GMj,,  
Y::fcMJr;Q  
,TOLr%+v~n  
public FileAccessI(String sName,long nPos) throws IOException ) EEr?"  
{ 7t5X  
oSavedFile = new RandomAccessFile(sName,"rw"); 7oF`Os+U  
this.nPos = nPos; oF.Fg<p(  
oSavedFile.seek(nPos); N ED`GU  
} @5 kKMz  
9/}i6j8Z  
s7I*=}{g0.  
public synchronized int write(byte[] b,int nStart,int nLen) ,p1 (0i  
{ )oTEB#J  
int n = -1; Qat%<;P2  
try{ FvG9PPd  
oSavedFile.write(b,nStart,nLen); "x9xJ  
n = nLen; l4U& CA y  
} $2]1 3j  
catch(IOException e) MGc=TQ.  
{ BGOI$,  
e.printStackTrace (); Rt7}e09HV  
} *Vfas|3hZI  
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?#}=!$p  
return n; :m8ED[9b  
} ||`w MWq  
n#z^uq|v  
|GK [I  
} ^eM=h
 
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lx$Y-Tb^F  
/* \^Y#"zXo1  
**SiteInfoBean.java Ep5lmzg  
*/ l]WV?^*  
package NetFox; a47Btd'm  
8o-?Y.2  
(&x~pv"+  
public class SiteInfoBean { ?[RG8,B  
vR,HCI  
QIi*'21a+  
private String sSiteURL; //Site's URL pC8(>gV<h  
private String sFilePath; //Saved File's Path enG6T  
private String sFileName; //Saved File's Name YL){o$-N"J  
private int nSplitter; //Count of Splited Downloading File U%oI*  
1Dt"Rcn"4  
ujz %0Mq;  
public SiteInfoBean() !Q.c8GRUQ  
{//nSplitter的缺省值为5 V.y+u7<3}  
//default value of nSplitter is 5 M|n)LyL  
this("","","",5); %M}zi'qQ?  
} rFx2S  
/4_}wi\  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) te6[^_k  
{ ,<EmuEw |  
sSiteURL= sURL; H5&>Eny  
sFilePath = sPath; "3\RJ?eW:S  
sFileName = sName; /2FX"I[0V%  
this.nSplitter = nSpiltter; am%qlN<  
44%H? ,d  
1/c
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} @lTUag'U0  
7]nPWz1%*  
xR_]^Get  
public String getSSiteURL() >E]*5jqU  
{ ]m4LY.SQ  
return sSiteURL; gKYn*  
} uXhp+q\  
+B8Ut{l  
e\yj>tQJg  
public void setSSiteURL(String value) UD9h5PgT  
{ $35Oyd3s<  
sSiteURL = value; e. [+xOu`  
} b%oma{I=.c  

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public String getSFilePath() mceSUKI;L  
{ 1Rczf(,aT  
return sFilePath; =x7ODBYW^  
} Ev^Xs6 }"  
[w{ZP4d>  
whLske-  
public void setSFilePath(String value) R +\y".  
{ Ey6K@@%  
sFilePath = value; %1=W#jz  
} 2X*epU_1h  
yBl<E$=  
8vT:icl  
public String getSFileName() 2sU
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{ BKDWd]KEf  
return sFileName; 92SB'T>  
} ;JZXSM-3  
{xH \!!"T  
/ZzlC#`  
public void setSFileName(String value) s]I],>}RU  
{ 3R{-\
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sFileName = value; ;zCHEz  
} qnA:[H;F  
#-@{rgH  
JfVayI=  
public int getNSplitter() .1pEq~>  
{ yr=r?h}  
return nSplitter; $<aBawLZO  
} "|Pl(HX  
/C(L(
X  
YLCwo]\+>  
public void setNSplitter(int nCount) a6]!4  
{ sW]n~
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nSplitter = nCount; N!m%~},s//  
} \O0fo^+U,,  
} r[,KE.^6~#  
@"~\[z5  
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/* lyi}q"Kn*;  
**Utility.java !e7vc[N  
*/ )a}5\
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package NetFox;
)R|7> 97  
[-CG&l2?L  
-0]aOT--  
public class Utility { NRl"!FSD;"  
o}%fs *  
r zvX~B6  
public Utility() 2Z97Tq  
{ $?s^HKF~  
s{IoL_P
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} srS
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T9$U./69-L  
//线程睡眠 kDz
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public static void sleep(int nSecond) :1{j&$  
{ "/"qg  
try{ ;C
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Thread.sleep(nSecond); ~H$XSNPi  
} ex=~l O  
catch(Exception e) =aekY;/  
{ [_0g^(`  
e.printStackTrace (); j~{2fd<>  
} U=t'>;(g  
} MvW>ktkU  
3K{8sFDO  
//日志 P$QjDu-  
public static void log(String sMsg) x3P@AC$\  
{ _kd
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System.err.println(sMsg); Z\L@5.*ydE  
} _qg6( X  
%b?Pasf.  
&-*nr/xT  
public static void log(int sMsg) Z`*c
I   
{ D=\|teA&  
System.err.println(sMsg); 6a@~;!GlI  
} BNy"YK$  
} 4W?<hv+k7*  
WAa?$"U2  
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/* 47
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**TestMethod.java zb" hy"hKw  
*/ Qx6/QaS?  
package NetFox; {eXYl[7n  
J v#^GNm  
vhHMxOZ;  
public class TestMethod { n1t(ns
|  
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s]N-n?'G"  
public TestMethod() j[fQs,efK  
{ ///xx/weblogic60b2_win.exe LnDj   
try{ QdTe!f|  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); AH`15k_i  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); </X"*G't  
SiteFileFetch fileFetch = new SiteFileFetch(bean); .#@Dn(  
fileFetch.start(); c{Kl?0#[  
} (2li:1j  
catch(Exception e){e.printStackTrace ();} nADd,|xD3  
/ZDc=>)~  
{X$Mwqhpp;  
}  SoX V  
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public static void main(String[] args) Ic}ofBK  
{ ~Hs{(7  
new TestMethod(); dO[4}FZ$  
} ]KeNC)R  
} _p&$X  
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