http断点续传简单实现（java)

/* pW3^X=6  
**SiteFileFetch.java q(84+{>B  
*/ vr=#3>  
package NetFox; +CNv l  
import java.io.*; ( a#BV}=  
import java.net.*; v.qrz"98-  
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public class SiteFileFetch extends Thread { ^ [@,  
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SiteInfoBean siteInfoBean = null; //文件信息Bean N~'c_l  
long[] nStartPos; //开始位置 D*d]aC  
long[] nEndPos; //结束位置 ]
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 PEZ!n.'S  
long nFileLength; //文件长度 oOFVb5qoFU  
boolean bFirst = true; //是否第一次取文件 4o[{>gW  
boolean bStop = false; //停止标志 "^GGac.  
File tmpFile; //文件下载的临时信息 \dah^mw"  
DataOutputStream output; //输出到文件的输出流 )Pv%#P-<  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） + {'.7#  
public SiteFileFetch(SiteInfoBean bean) throws IOException uwGc@xOgg,  
{ A.w.rVDD  
siteInfoBean = bean; 'm$L Ij?@  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); DN6Mo<H  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 3u0RKLc\  
if(tmpFile.exists ()) Iu=(qU  
{ f3y=Wxk[  
bFirst = false; c-sfg>0^  
read_nPos();
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} |2A:eI8 ^  
else y?3;06y|  
{ K{+2G&i  
nStartPos = new long[bean.getNSplitter()]; KMax$  
nEndPos = new long[bean.getNSplitter()]; t%8BK>AHvw  
} G 01ON0  
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} 5)X=*I  
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public void run() R=\IEqqsi  
{ ~a2}(]  
//获得文件长度 !dq.KwL  
//分割文件 w,D+j74e$  
//实例FileSplitterFetch j1<Yg,_.p  
//启动FileSplitterFetch线程 E!F^H^~$8  
//等待子线程返回 &UFZS94@r  
try{ ~wdGd+ez  
if(bFirst) #AY&BWS$  
{ gjlx~.0d  
nFileLength = getFileSize(); +lTq^
4  
if(nFileLength == -1) \Vk:93OH21  
{ Q+{n-? :  
System.err.println("File Length is not known!"); Nz-&MS  
} );YDtGip J  
else if(nFileLength == -2) %BQ`
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{ BnY&f  
System.err.println("File is not access!"); Q,Eo mt  
} k;Y5BB  
else kq-) ^,{y  
{ 19#\+LWA  
for(int i=0;i<nStartPos.length;i++) D2O~kNd  
{ 3OB"#Ap8<  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); &7s.`  
} 4skD(au8  
for(int i=0;i<nEndPos.length-1;i++) %a7$QF]  
{ e|r`/:M  
nEndPos = nStartPos[i+1]; x?<FJ"8"k  
} B#R|*g:x  
nEndPos[nEndPos.length-1] = nFileLength; EdX$(scu~B  
} NHE18_v5  
} !VzC&>'v^9  
~$J2g  
ia? c0xL  
//启动子线程 B)UZ`?>c  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; yt2PU_),  
for(int i=0;i<nStartPos.length;i++) RM/ 0A|  
{ E?@m?@*/  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), CvdN"k  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), : rVnc =k  
nStartPos,nEndPos,i); cz$2
R  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); /mZE/>&~,  
fileSplitterFetch.start(); Zwx%7l;C  
} 19] E 5'AI  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !<h)w#>en  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); xyxy`qRA  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", @(lh%@hO  
nEndPos = " + nFileLength); l+b~KU7~l  
// fileSplitterFetch[nPos.length-1].start(); |vC~HJpuv'  
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//等待子线程结束 1 -b_~DF  
//int count = 0; $pz/?>!  
//是否结束while循环 +cRn%ioVi  
boolean breakWhile = false; [N'h%1]\  

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while(!bStop) h@BY]80  
{ wgA_38To  
write_nPos(); y)<q/  
Utility.sleep(500); to&m4+5?6  
breakWhile = true; [-x7_=E#  
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for(int i=0;i<nStartPos.length;i++) oL<St$1  
{ KY^
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if(!fileSplitterFetch.bDownOver) "wc<B4"  
{ 2Z%O7V~u  
breakWhile = false; D43z9z-:L  
break; ss-D(K"  
} e:W{OIz:  
} c*M}N?|6  
if(breakWhile) I}Q2Vu<  
break; XfmwVjy  
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i mM_H;-X  
//count++; 0CvUc>Pj`"  
//if(count>4) -{A<.a3P}=  
// siteStop(); J8D,ZfPN`d  
} o"SMbj  
QSj]ZA  
L%5%T;0'~  
System.err.println("文件下载结束！"); \j.:3Xr  
} p4)Q&k!  
catch(Exception e){e.printStackTrace ();} wNX]7wMX  
} ?%kV?eu'  
|7Kbpj  
S[QrS7  
//获得文件长度 E)3NxmM#  
public long getFileSize() C*lJrFpB  
{ (iGTACoF  
int nFileLength = -1; B?wq=DoG  
try{ zMJT:7*`|  
URL url = new URL(siteInfoBean.getSSiteURL()); Wez5N  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Q=:|R
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httpConnection.setRequestProperty("User-Agent","NetFox"); BORA(,  
LHmZxi?  
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int responseCode=httpConnection.getResponseCode(); eiOW#_"\  
if(responseCode>=400) 9ll~~zF99|  
{ "ITIhnE  
processErrorCode(responseCode); 5(8@%6>ruj  
return -2; //-2 represent access is error Ct|A:/z(  
} _aMF?Pj~m  
'H!XUtFs"  
FgI3   
String sHeader; l+0P  
?hM64jI|  
3ANQaUC  
for(int i=1;;i++) A(N4N  
{ \
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); XZwK6F)L  
//Utility.log(in.readLine()); c"xK`%e  
sHeader=httpConnection.getHeaderFieldKey(i); \C1nZk?3  
if(sHeader!=null) ,=N.FS  
{ $7uA%|\  
if(sHeader.equals("Content-Length")) HorDNRyu  
{ p<;0g9,1  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ,Lt[\_  
break; iyog`s c  
} 39jG8zr=Z[  
} -{+}@?  
else w*MpX U<  
break; wdZ/Xp9]  
} #89!'W  
} =rK+eG#,  
catch(IOException e){e.printStackTrace ();} >OK^D+v"j  
catch(Exception e){e.printStackTrace ();} 8.~kK<)!  
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Utility.log(nFileLength); D,ln
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return nFileLength; 6`-jPR  
} ,?XCyHSgWW  
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c0fo7|  
//保存下载信息（文件指针位置） 3[f): u3"  
private void write_nPos() <^uBoKB/f  
{ 3D(0=$W  
try{ <Ok3FE.K  
output = new DataOutputStream(new FileOutputStream(tmpFile)); o8vug$=Z  
output.writeInt(nStartPos.length); nNU2([  
for(int i=0;i<nStartPos.length;i++) 4H<lm*!^  
{ ?0,Ngrbe  
// output.writeLong(nPos); dq[xwRU1  
output.writeLong(fileSplitterFetch.nStartPos); DFTyMB1H  
output.writeLong(fileSplitterFetch.nEndPos); "wHFN>5B  
} 8e|%M  
output.close(); :a)u&g@G  
} ?pZOeqqu$  
catch(IOException e){e.printStackTrace ();} kSh( u  
catch(Exception e){e.printStackTrace ();} ?F;8Pa/  
} !v0LBe4  
>dG[G>  
C>w|a  
//读取保存的下载信息（文件指针位置） 6MkP |vr6  
private void read_nPos() w+{LAS  
{
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try{ O0y_Lm\  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); -D$8  
int nCount = input.readInt(); m9Hit8f@Q  
nStartPos = new long[nCount]; i7>tU=  
nEndPos = new long[nCount]; bY0|N[g  
for(int i=0;i<nStartPos.length;i++) n.G!43@*N  
{ VU d\QR-  
nStartPos = input.readLong(); !GGkdg*-*9  
nEndPos = input.readLong(); I.k *GW  
} 6i~WcAs  
input.close(); Ue~CwFOc  
} LE>]8[f6S  
catch(IOException e){e.printStackTrace ();} d<N:[Y\4l  
catch(Exception e){e.printStackTrace ();} `$C n~dT  
} \;"=QmRD%:  
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d;}nh2*  
private void processErrorCode(int nErrorCode) #ucBo<[  
{ & 9 ?\b7  
System.err.println("Error Code : " + nErrorCode); )%@J=&G8TT  
} qm o9G  
0=E]cQwh  
4Wm@W E  
//停止文件下载 l2P=R)@{  
public void siteStop() 'CkIz"Wd  
{ $'hEz/  
bStop = true; n#OB%@]<V  
for(int i=0;i<nStartPos.length;i++) %Qdn  
fileSplitterFetch.splitterStop(); d4c8~L H-  
)f<z%:I+Z  
}d}Ke_Q0  
} X*@dj_,  
} Ru
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//负责部分文件的抓取 ` v@m-j6  
**FileSplitterFetch.java -I,$_  
*/ cq/$N  
package NetFox; 'u |c  
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import java.io.*; 6MMOf\   
import java.net.*; cP_.&!T  
I75DUJqy]  
&AbNWtCV+G  
public class FileSplitterFetch extends Thread { -0x #  
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(S\[Y9  
String sURL; //File URL zsyIV!(  
long nStartPos; //File Snippet Start Position #KexvP&*  
long nEndPos; //File Snippet End Position o
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int nThreadID; //Thread's ID aH/ k
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boolean bDownOver = false; //Downing is over k5.Ln
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boolean bStop = false; //Stop identical X))/ m[_[  
FileAccessI fileAccessI = null; //File Access interface <s<n  
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p xa*'h"b^  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException PKg@[<g43  
{ U6fgo3RH  
this.sURL = sURL; R3&Iu=g  
this.nStartPos = nStart; MC.)2B7  
this.nEndPos = nEnd; V7fq4O^:  
nThreadID = id; "Nbq#w\  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /zVOK4BqN+  
} WX|`1b  
qwgPk9l  
j0evq+  
public void run() Ata:^q
I  
{ 1+{{EOZ4  
while(nStartPos < nEndPos && !bStop) %oa-WmWm  
{ ywm8N%]v  
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hVAn>_(  
try{ RF53Jyt  
URL url = new URL(sURL); "2$fi{9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 'Nnzk  
httpConnection.setRequestProperty("User-Agent","NetFox"); ""F5z,'  
String sProperty = "bytes="+nStartPos+"-"; f=gW]x7'R+  
httpConnection.setRequestProperty("RANGE",sProperty); V/ uP%'cd  
Utility.log(sProperty); k(7&N0V%zz  
iYm-tsER;  
.P%bkD6M  
InputStream input = httpConnection.getInputStream(); `
1{ZqRFQ  
//logResponseHead(httpConnection); F]]]y5t  
q"sed]  
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byte[] b = new byte[1024]; %JD,$pPs  
int nRead; dkBIx$t  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ^{;oM^Q'  
{ Z<y I\1  
nStartPos += fileAccessI.write(b,0,nRead); [KaAXv .X  
//if(nThreadID == 1) ^-Kf']hU  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); V0.vQ/  
}
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as4;:  
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Utility.log("Thread " + nThreadID + " is over!"); u^bidd6JRn  
bDownOver = true; sF?TmBQ*  
//nPos = fileAccessI.write (b,0,nRead); Jg\zdi:t  
} j0S#>t  
catch(Exception e){e.printStackTrace ();} 1&evG-#<:  
} Gm.T;fc:  
} ujq=F  
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//打印回应的头信息 ]kRfB:4ED  
public void logResponseHead(HttpURLConnection con) "ZoRZ'i  
{ z] PS
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for(int i=1;;i++) }mq6]ZrK  
{ wyj{zWRJp  
String header=con.getHeaderFieldKey(i); xU>WEm2  
if(header!=null) a#y;d
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); l%puHZ)t  
Utility.log(header+" : "+con.getHeaderField(header)); 5Y'qaIFR  
else ~f1%8z  
break; lVR~Bh  
} _j/<{vSy  
} #TX/aKr:  
E+R1 !.  
q`H_M{26!y  
public void splitterStop() mD0f<gJ1  
{ ith 3=`3  
bStop = true; M!A}NWF  
} A8fOQ  
;F!5%}OcL%  
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} aS{n8P6vW  
(*nT(Adk  
[.'|_l  
/* y'~U%,ki6  
**FileAccess.java +]A:M6P:{v  
*//文件访问(定位，写) 3kIN~/<R+7  
package NetFox; Ym{tR,g7  
import java.io.*; ?U5{Wa85D  
6?mibvK  
C]eSizS.  
public class FileAccessI implements Serializable{ '}JhzKNj  
X!
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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 B=y
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RandomAccessFile oSavedFile; K{cD+=
]{  
long nPos; DV+xg3\(>1  
t?ZI".>  
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public FileAccessI() throws IOException YEs&  
{ R{3N&C  
this("",0); YX7L?=;.@  
} *:YiimOY"  
!M]uL&:  
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public FileAccessI(String sName,long nPos) throws IOException >#;.n(y  
{ BNl5!X^{  
oSavedFile = new RandomAccessFile(sName,"rw"); c74.< @w  
this.nPos = nPos; 6C^ D#.S  
oSavedFile.seek(nPos); m
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} -MO#]K3<  
./k/KSR  
@ ZwvBH  
public synchronized int write(byte[] b,int nStart,int nLen) G5RR]?@6V  
{ Zq|I,l0+E  
int n = -1; t#/YN.@r  
try{ !t%j?\f  
oSavedFile.write(b,nStart,nLen); VT%NO'0  
n = nLen; trA4R/ &  
} :P\7iW  
catch(IOException e) Ic:(Gi- %  
{ ,I$`-$_'  
e.printStackTrace (); el<s8:lA  
} WZejp}x  
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return n; Ae^~Cz1qz  
} 3!Ij;$  
tr3!d_  
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} %lx!.G  
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/* He/8=$c%  
**SiteInfoBean.java +I:Unp  
*/ };bEU wGWf  
package NetFox; 
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uR4z&y  
PbgP\JeX  
public class SiteInfoBean { "f2$w  
9:[ 9v  
Lpz>>}  
private String sSiteURL; //Site's URL ,GIyq)  
private String sFilePath; //Saved File's Path `?qF$g9u~  
private String sFileName; //Saved File's Name n;Q7X>-f8`  
private int nSplitter; //Count of Splited Downloading File g i-$ZFzB  
:&rt)/I  
H8zK$!  
public SiteInfoBean() \*y-g@-{W$  
{//nSplitter的缺省值为5 V-2(?auZd  
//default value of nSplitter is 5 v0+BkfU+p  
this("","","",5); 4qh?,^Dq  
} \0I_<  
#n#}s  
n;C :0  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Apag{Z]^B  
{ m@F`!qY~Y\  
sSiteURL= sURL; ~&_z2|UXp  
sFilePath = sPath; x8\?}UnB  
sFileName = sName; JCzeXNY  
this.nSplitter = nSpiltter; =sU<S,a*  
D~iz+{Q4  
-1_)LO&H  
} !bx;Ta.  
e8!5I,I  
8oseYH  
public String getSSiteURL() ")5":V~fN  
{ syj0.JD  
return sSiteURL; l -mfFN  
} {n.PF8A5X  
El".I?E*  
7\[@m3s  
public void setSSiteURL(String value) :T$|bc  
{ r~8 $1"  
sSiteURL = value; q=m'^ ,gPS  
} <CiSK!  
]t,BMu=%  
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public String getSFilePath() @6sqMw}  
{ Hqx-~hQO  
return sFilePath; KYhwOGN  
} b<ZIWfs  

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public void setSFilePath(String value) aEWWP]  
{ ^j7Vt2-  
sFilePath = value; 6=/F$|  
} A#<?4&  
V>LwqS~`  
.},'~NM]  
public String getSFileName() .bg~>T+<  
{ l0m-$/  
return sFileName; EU;9*W<  
} >dD@j:Qc  
(@VMH !3  
70nqD>M4  
public void setSFileName(String value) L,`LN>  
{ X-Kh(Z  
sFileName = value; 2(+
2+}  
} q`a'gJx#y  
1#2 I  
@%uUiP0  
public int getNSplitter() @ioJ]$o7  
{ E_wCN&`[  
return nSplitter; [ /b2=>  
} g2ixx+`?|:  
lU\[aNs  
]^7@}Ce_  
public void setNSplitter(int nCount) h"Q8b}$^)  
{ b3[!V{|  
nSplitter = nCount; !hy-L_wL]  
} q!7ANib6O  
} UnV.~u~  
,PW'#U:  
<2x^slx)?  
/* i$#;Kpb`^  
**Utility.java 5H9z4-i x?  
*/ gPO}d  
package NetFox; KYI/  
TDjm2R~9FS  
"m8^zg hL  
public class Utility { @n /nH?L  
~jk|4`I?T  
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public Utility() 9:|{6_Y  
{ #q$HQ&k  
ZJJY8k `  
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} lgy<?LI\  
!i}w~U<  
//线程睡眠 8/cX]J  
public static void sleep(int nSecond) 5Ln,{vsv  
{ M FMs[+2_o  
try{ BwpqNQN  
Thread.sleep(nSecond); &wawr2)}  
} Q"d^_z]K  
catch(Exception e) &PHTpkaam  
{ ;xj?z\=Pg  
e.printStackTrace (); |SSSH  
} /C:gKy4  
} : *#-%0  
o5PO=AN  
//日志 rXP,\ ]r+  
public static void log(String sMsg) AV]2euyn  
{ my1@41 H  
System.err.println(sMsg); l|[N42+  
} *:7rdzn  
v!-pSa)3  
qYQl,w  
public static void log(int sMsg) !9e=_mY  
{ ~G&dqw/.-U  
System.err.println(sMsg); `
/+>a8  
} %aCqi(.7  
} i1d'nxk6  
EME|k{W  
]s'as9s9  
/* Q3~H{)[Kq  
**TestMethod.java a58H9w"u)  
*/ fTec  
package NetFox; 9W5lSX#^;  
;H*T^0  
eo?bL$A[s  
public class TestMethod { ;igIZ$&  
|wMN}bq|T  
sll\g  
public TestMethod() ]F~dlH1Wp
 
{ ///xx/weblogic60b2_win.exe %[TR^Th6
 
try{ :3Ox~o  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 
|HQW0  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); !;A\.~-!G  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ;$|nrwhy  
fileFetch.start(); \gaw6S>n}  
} Wn2NMXK  
catch(Exception e){e.printStackTrace ();} ^^$s%{ep"  
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U7F!Z( 9  
} B9z?mt'|r)  
JH9J5%sp  
LH% F8  
public static void main(String[] args) vvMT}-!  
{ CAhXQ7w'Z  
new TestMethod(); FW4<5~'  
} 6nvz8f3*r]  
} #c!lS<z  
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