http断点续传简单实现（java)

/* [b/o$zR  
**SiteFileFetch.java &94W-zh  
*/ xS8,W  
package NetFox; fu R2S70d  
import java.io.*; Svw<XJ   
import java.net.*; I^_NC&m  
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public class SiteFileFetch extends Thread { ag8`O&+  
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+sf .PSz$  
SiteInfoBean siteInfoBean = null; //文件信息Bean !^WHZv4  
long[] nStartPos; //开始位置 H0>yi[2f  
long[] nEndPos; //结束位置 f~ZEdq8  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 6kR\xP]Kr  
long nFileLength; //文件长度 SK R1E];4  
boolean bFirst = true; //是否第一次取文件 I[D8""U  
boolean bStop = false; //停止标志 BzN@gQo  
File tmpFile; //文件下载的临时信息 |^( M{  
DataOutputStream output; //输出到文件的输出流 z9DcnAs  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） x[i`S8D  
public SiteFileFetch(SiteInfoBean bean) throws IOException zzIr2so  
{ ~<)vKk  
siteInfoBean = bean; 6B6vP%H#  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); |PP.<ce\-  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); h@1!T  
if(tmpFile.exists ()) VkZ.6kV  
{ =Op+v"  
bFirst = false; "2{%JFE  
read_nPos(); I ~$1Lu`~  
} P@0Y./Ds  
else |"]PCb)!  
{ qP1FJ89
H  
nStartPos = new long[bean.getNSplitter()]; Vn|1v4U!  
nEndPos = new long[bean.getNSplitter()]; I7(?;MpI  
} nidr\oFUIn  
Zu/<NC (  
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} QDTNx!WL  
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ub K7B |p  
public void run() rv7{Ow_Y  
{ qCPmbg  
//获得文件长度 %d;ezY'2  
//分割文件 Q(Gl{#b  
//实例FileSplitterFetch nwmW.(R4  
//启动FileSplitterFetch线程 *%gF2@=r8F  
//等待子线程返回 
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try{ igC_)C^i>  
if(bFirst) c#cx>wq9  
{ $`J_:H%  
nFileLength = getFileSize(); #07!-)Gv  
if(nFileLength == -1) ST dNM\+  
{ ~Z)/RT/  
System.err.println("File Length is not known!"); W|5_$p  
} Um.qRZ?  
else if(nFileLength == -2) cg{AMeW  
{ Log|%P\  
System.err.println("File is not access!"); sa&) #Z:  
} 3tAU?sV!  
else ytAWOt}`  
{ \6!W05[ Q  
for(int i=0;i<nStartPos.length;i++) y~ rXl  
{ `T&jPA9eY  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Jn&7C  
} @)6jE!LC  
for(int i=0;i<nEndPos.length-1;i++) pv,45z0
 
{ `[fxyg:u  
nEndPos = nStartPos[i+1]; .uz|/Zy  
} =O$M_1lp  
nEndPos[nEndPos.length-1] = nFileLength; "TOa=Tt{,  
} ('[TLHP  
} gm)@c2?.  
quxdG>8  
* ?Jz2[B  
//启动子线程 ,5Vt]#F5@  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; jp2Q9Z  
for(int i=0;i<nStartPos.length;i++) 0<p{BL8  
{ v6=-g$FG  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), R[B?C;+(O  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), j+IrqPKC^  
nStartPos,nEndPos,i); Rl~T$ Ey  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 60>.ul2  
fileSplitterFetch.start(); Zu*K-ep"  
} X[yNFW}S2W  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), na+d;h*~y  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); F7*wQ{~  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 9&]M**X  
nEndPos = " + nFileLength); \wvg,j=  
// fileSplitterFetch[nPos.length-1].start(); 0Q5^C!K  
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OQ
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//等待子线程结束 p *w$:L  
//int count = 0; d^E [|w;  
//是否结束while循环 Vr.Y/3N&'  
boolean breakWhile = false; iEyeX0nm  
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while(!bStop) Di.3113t  
{ Xd `vDgD  
write_nPos(); TI|/u$SJ<Z  
Utility.sleep(500); PJ4(}a  
breakWhile = true; k?GD/$1t  
i
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?/hZb"6W  
for(int i=0;i<nStartPos.length;i++) "2ru7Y"  
{ _HOIT  
if(!fileSplitterFetch.bDownOver) wf.T3  
{ JYb}Zw;  
breakWhile = false; O[@q%&_  
break; pKG<Nvgz&  
} 3>M&D20Z  
} /b#l^x:j  
if(breakWhile) Ta=s:trP  
break; e.d #wyeX  
bpAv1udX-W  
nk"NmIf  
//count++; (rtY!<|p  
//if(count>4) \c,pEXG  
// siteStop(); DL^o
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} 
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aW_oD[l  
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System.err.println("文件下载结束！"); &<TzGB*  
} Hy:V`>  
catch(Exception e){e.printStackTrace ();} HvwYm.$zE  
} `mfq 2bVc  
Fh|#u:n  
SymwA
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//获得文件长度 g^Yl TB  
public long getFileSize() g]~h(mI  
{ CBYX]  
int nFileLength = -1; PQmq5N6  
try{ $lA V6I.  
URL url = new URL(siteInfoBean.getSSiteURL()); Z6C=T;w  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); uQ$^;Pr  
httpConnection.setRequestProperty("User-Agent","NetFox"); :'L2J  
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int responseCode=httpConnection.getResponseCode(); .R*!aK  
if(responseCode>=400) .jw}JJ  
{ {]*x*aa\  
processErrorCode(responseCode); !`JHH&  
return -2; //-2 represent access is error aVs(EHF  
} O43YY2  
$q?$]k|M`  
Wm~` ~P  
String sHeader; 8F(h*e_?  
R:-JkV>e:  
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for(int i=1;;i++) P;[OWSR[d  
{ 1F'1>Bu~  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); <:>SGSE9  
//Utility.log(in.readLine()); &GTI  
sHeader=httpConnection.getHeaderFieldKey(i); EI>6Nh  
if(sHeader!=null) %=we`&  
{ 9h90huyKF  
if(sHeader.equals("Content-Length")) lASL8O&\  
{ n]_[NR) i  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 7M_U2cd|TD  
break; gbeghLP[?  
} sxKf&p;  
} ?^mi3VM  
else 5<pftTcZ  
break; kv,%(en]  
} D-Vai#Cd  
} AE`We$!  
catch(IOException e){e.printStackTrace ();} >KLtY|o)  
catch(Exception e){e.printStackTrace ();} AUVgPXOwd  
o;a:Dd  
6Tw#^;q-  
Utility.log(nFileLength); % }|cb7l  
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return nFileLength; enNiI$H]`_  
} m"\:o  
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h  
B&+`)E{KB  
//保存下载信息（文件指针位置） aJL^AG  
private void write_nPos() AsS$C&^  
{ =p^He!  
try{ n~V4nj&_T  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 1(zsOeX  
output.writeInt(nStartPos.length); v8gdU7Ll,  
for(int i=0;i<nStartPos.length;i++) )Au6Nf  
{ "vCM}F  
// output.writeLong(nPos); GuZ( &G6*  
output.writeLong(fileSplitterFetch.nStartPos); 4H5pr  
output.writeLong(fileSplitterFetch.nEndPos); /&& 2u7*  
} U-k+9f 0  
output.close(); UX3BeUi.)  
} b*;"q9u5  
catch(IOException e){e.printStackTrace ();} 2$_9cF Wm  
catch(Exception e){e.printStackTrace ();} XoLJL]+?  
} [ xOzzp4  
9`jcC-;iv  
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//读取保存的下载信息（文件指针位置） k%wn0Erd  
private void read_nPos() Xtz-\v#0o'  
{ IKtB;  
try{ s]T""-He  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); n?\ nn3  
int nCount = input.readInt(); `nKH"TaX  
nStartPos = new long[nCount]; ""Zp:8o  
nEndPos = new long[nCount]; ^JZ^>E~  
for(int i=0;i<nStartPos.length;i++) i&njqK!wS  
{ >-_d CNZ  
nStartPos = input.readLong(); L@75-T  
nEndPos = input.readLong(); G$'jEa<:u  
} ri`R<l8  
input.close(); _LAS~x7,  
} HkV1sT  
catch(IOException e){e.printStackTrace ();} A7!g  
catch(Exception e){e.printStackTrace ();} #po5_dE\*  
} lf>*Y.!@me  
{mWui9 %M  
}>^Q'BW;65  
private void processErrorCode(int nErrorCode) 4L-:*b_v\  
{ R(P%Csbqh  
System.err.println("Error Code : " + nErrorCode); )&era` e[  
} Uie?9&3  
R1F5-#?'E  
{7!UQrm<  
//停止文件下载 /vY_Y3k#  
public void siteStop() !3mA0-!+  
{ fP3_d  
bStop = true; 9_\'LJ  
for(int i=0;i<nStartPos.length;i++) ;fw1
 
fileSplitterFetch.splitterStop(); ky 8ep  
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j-CnT)W<  
} Ngr/QL]Q  
} %}86D[PF  
//负责部分文件的抓取 M :3u@06a  
**FileSplitterFetch.java fgNU03jp^x  
*/ K.G$]H  
package NetFox; J};z85B  

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import java.io.*; 7'wS\/e4a  
import java.net.*; ]M)O YY  

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public class FileSplitterFetch extends Thread { bX.ja;;   
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String sURL; //File URL kc7l
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long nStartPos; //File Snippet Start Position Oz|K8p  
long nEndPos; //File Snippet End Position 79\JxiSB  
int nThreadID; //Thread's ID ?JV|dM  
boolean bDownOver = false; //Downing is over 6"c1;P!4   
boolean bStop = false; //Stop identical V{|}}b?w?  
FileAccessI fileAccessI = null; //File Access interface x^"ES%*  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException kc/{[ME  
{ }M1sksk5
 
this.sURL = sURL; ZEYgK)^  
this.nStartPos = nStart; t_ks
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this.nEndPos = nEnd; _k^0m
 
nThreadID = id; %/>xO3"T  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 X2tk[Kr  
} "<}&GcJbz  
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A2}Rl%+X]6  
public void run() MNH1D!}  
{ }HE6aF62O  
while(nStartPos < nEndPos && !bStop) sC[yI Up  
{ y9#$O(G  
y=Mq(c:'UN  
jCTAKaq  
try{ +0),xu   
URL url = new URL(sURL); 0l;<5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); H+ h07\? %  
httpConnection.setRequestProperty("User-Agent","NetFox"); R<i38/ ~G  
String sProperty = "bytes="+nStartPos+"-"; 9Pw0m=4  
httpConnection.setRequestProperty("RANGE",sProperty); 1 T130L  
Utility.log(sProperty); T[=S$n-'  
gyS+9)gY  
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InputStream input = httpConnection.getInputStream(); E7Cy(LO  
//logResponseHead(httpConnection); +UJuB  
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byte[] b = new byte[1024]; +GsWTEz  
int nRead; jGrN\D?h  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) X0-IRJ[  
{ dD<fn9t  
nStartPos += fileAccessI.write(b,0,nRead); lnE+Au'  
//if(nThreadID == 1) ]|_\x
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); e!fqXVEVR  
} 65ly2gl  
;n\= R 5.  
[i0Hm)Bd3  
Utility.log("Thread " + nThreadID + " is over!"); TpA\9N#$  
bDownOver = true; fQLt=Lrp  
//nPos = fileAccessI.write (b,0,nRead); qyHZ M}/  
} (Qgde6  
catch(Exception e){e.printStackTrace ();} 2xw6 5z  
} smG>sEp2  
} S osj$9E  
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IlX$YOf4  
//打印回应的头信息 O4<g%.HC6  
public void logResponseHead(HttpURLConnection con) a?yMHb{F  
{ Z ,^9Z  
for(int i=1;;i++) ^IKO2Ft
 
{ {brMqE>P#  
String header=con.getHeaderFieldKey(i); kj+
#TnF-  
if(header!=null) &rDM<pO #-  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); :b[` 
v  
Utility.log(header+" : "+con.getHeaderField(header)); }HEvr)v9  
else `si#aU  
break; `V[!@b:  
} iut`7  
} ,Ma.V\T[  
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public void splitterStop() -/]W+[  
{ t>B^q3\q?  
bStop = true; rQTr8DYH  
} Ax oD8|  
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} ?=GXqbS"  
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/* ]4+s$rG  
**FileAccess.java tweY'x.{  
*//文件访问(定位，写) )'l*Tl  
package NetFox; Khh0*S8.K  
import java.io.*; $4jell  
_ >`X]I;  
tU"raP^=  
public class FileAccessI implements Serializable{ bbxLBD'  
rzp +:  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 UR(-q  
RandomAccessFile oSavedFile; W~_t~Vg5  
long nPos; 5q@LxDy,b  
7j5f ;O^+  
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public FileAccessI() throws IOException K!D o8|  
{ \yrisp#`  
this("",0); hO{cvHy`  
} > Oh?%%6  
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public FileAccessI(String sName,long nPos) throws IOException &iN--~}!$  
{ xr0haN\p"  
oSavedFile = new RandomAccessFile(sName,"rw"); *zO&N^X.4  
this.nPos = nPos; ck#"*],  
oSavedFile.seek(nPos); L]a`"CH:a$  
} VC5_v62&.  
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public synchronized int write(byte[] b,int nStart,int nLen) BiE08,n
j  
{ >#+IaKL7  
int n = -1; Y}6n]n;uR  
try{ }awzO#  
oSavedFile.write(b,nStart,nLen); 4eVI},  
n = nLen; -
#-p1^v}  
} Dj\e@?Y  
catch(IOException e) n{*e 9Aw  
{ nZR!*$}A  
e.printStackTrace (); v;{{ y-  
} 7iuQ9q^&  
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return n; CeT~p6=  
} mq/zTm  
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} l? #xAZx&_  
.AV)'j#6P  
/EwGW  
/* {>0V[c[~  
**SiteInfoBean.java 0f ER*.F  
*/ t?;T3k[RM  
package NetFox; %Qn(rA@9  
"a1O01n  
7#;vG>]  
public class SiteInfoBean { HOt>}x  
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private String sSiteURL; //Site's URL ]O:M$ $  
private String sFilePath; //Saved File's Path NGjdG=,  
private String sFileName; //Saved File's Name jW*1E*"  
private int nSplitter; //Count of Splited Downloading File B1N)9%  
l#3($QV,  
s(ROgCO
 
public SiteInfoBean() $awi>#[  
{//nSplitter的缺省值为5 zIQzmvf  
//default value of nSplitter is 5 :lcea6iO  
this("","","",5); 9T2xU3UyY  
} 4C~UcGMv\  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 'p)Q68;&  
{ KB{RU'?f|  
sSiteURL= sURL; vnX  
sFilePath = sPath; x_@i(oQ:_  
sFileName = sName; y_F}s9wj  
this.nSplitter = nSpiltter; %@&a7JOL  
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} OVoO6F]  
fF?6j  
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public String getSSiteURL() w=r&?{  
{ t7#lsd`_  
return sSiteURL; ,W5.:0Y;f[  
} ?s} %  
vfvlB[  
5#:pT  
public void setSSiteURL(String value) lHBI  
{ Dxx;v.$  
sSiteURL = value; ru.5fQU  
} )&NAs  
t\U$8l_;  
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public String getSFilePath() {'3D1#SK  
{ +
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return sFilePath; >POO-8Q  
} X\GM/A  
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public void setSFilePath(String value) u,i]a#K  
{ wuK=6RL  
sFilePath = value; I{.HO<$7D}  
} "mj^+u-  
m$UvFP1>u1  
~2%3FV^
 
public String getSFileName() i3V/`)iz  
{ o 5Zyh26  
return sFileName; [$:,-Q@  
} MB$a82bY  
3_ 2hC!u!K  
w[fDk1H)  
public void setSFileName(String value) :uCdq`SaQl  
{ G\Hq/4  
sFileName = value; ;i)KHj'  
} 2/Nq'  
-Q[g/
%  
=:$) Z  
public int getNSplitter() _,;%mK  
{ hYt7kq!"  
return nSplitter; 9 pKm*n&  
} X BI;Lg  
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public void setNSplitter(int nCount) DnyYMe!r  
{ @@pq'iRn  
nSplitter = nCount; q(9%^cV6  
} xEoip?O?7F  
} r#h {$i
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9`X&,S~e  
/* N=fz/CD)I  
**Utility.java Bhuw(KeB  
*/ 8]*Q79  
package NetFox; |$w*RI0C  
Z.jCera.  
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public class Utility { b~wKF0vq  
'C]jwxy  
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public Utility() c cr
" ep  
{ zGs|DB  
/Dd\PjIH{  
&+;uZ-x  
} cIZc:   
JLW$+62  
//线程睡眠 Q_lu`F|  
public static void sleep(int nSecond) EVz9WY  
{ S:97B\u`  
try{ &-F"+v,+  
Thread.sleep(nSecond); kk
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} RjtC:H&XZ  
catch(Exception e) -N^=@Yx)  
{ Yf(im  
e.printStackTrace (); D0M!"c>\  
}  GVp  
} O]_={%   
&wGg6$  
//日志 rt;gC[3\  
public static void log(String sMsg) b+$o4l/x  
{ F?2FITi_V  
System.err.println(sMsg); qRUCnCZs  
} eiB(VOJ  
Ar~{=X  
32KR--mn%  
public static void log(int sMsg) 9S"N4c>  
{ ,?w!5N;iRO  
System.err.println(sMsg); _h~p:=  
} {d}26 $<$]  
} N l|^o{#  
MgP{W=h2  
p2a?9R  
/* a@k.$  
**TestMethod.java 2VMX:&3 5J  
*/ P%jkKE?B4  
package NetFox; [Yoa"K  
3GINv3_  
x 8M#t(hw  
public class TestMethod { `vH&K{  
'Z$jBL  
}wG|%Y#+r  
public TestMethod() scmto cm  
{ ///xx/weblogic60b2_win.exe 3DI^y`av  
try{ aKOf;^@  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); C&oxi$J:p+  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ZpTi:3>  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 3Pa3f >}-  
fileFetch.start(); f-s~Q4  
} kI]=&Rw  
catch(Exception e){e.printStackTrace ();} {"}+V`O{  
z=%IcSx;  
&08Tns"  
} *|CLO|B)  
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>+f'!*%7He  
public static void main(String[] args) F]P
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{ nYgx9Q"<om  
new TestMethod(); &}O8w77  
} FBbm4NB  
} &BTfDsxAK  
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