http断点续传简单实现（java)

/* +IlQZwm~  
**SiteFileFetch.java ?5j~"  
*/ C)%qs]  
package NetFox; <%=<9~e  
import java.io.*; s$^2Qp  
import java.net.*; ]q&NO(:kbq  
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public class SiteFileFetch extends Thread { ^szi[Cj  
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SiteInfoBean siteInfoBean = null; //文件信息Bean f#gV>.P;h\  
long[] nStartPos; //开始位置 `A8ErfA  
long[] nEndPos; //结束位置 sR)jZpmC(  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 9d!mGnl  
long nFileLength; //文件长度 (N`GvB7;  
boolean bFirst = true; //是否第一次取文件 4Ujy_E?^  
boolean bStop = false; //停止标志 d\r-)VWSr"  
File tmpFile; //文件下载的临时信息 @eq.&{&  
DataOutputStream output; //输出到文件的输出流 x1}Ono3"T  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） pB7^l|\]  
public SiteFileFetch(SiteInfoBean bean) throws IOException ,}wFQ9*|W  
{ ^S!;snhn  
siteInfoBean = bean; xRqA^Ad  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); M6].V*k'2  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); .sKfwcYu4  
if(tmpFile.exists ()) 8uA!Vrp3  
{ Jw{duM;]  
bFirst = false; #RHt;SFx  
read_nPos(); Af`Tr6)  
} z8xBq%97us  
else Wmx3@]<  
{ +M<W8KF  
nStartPos = new long[bean.getNSplitter()]; //%#?JJV  
nEndPos = new long[bean.getNSplitter()]; 6-+wfrN2  
} Y)l=r^Ap>  
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} -x|!?u5F  
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public void run() dAy\IfZX=  
{ M;YJpi  
//获得文件长度 32`Z3-  
//分割文件 WADEDl&,'  
//实例FileSplitterFetch R]0`-_T  
//启动FileSplitterFetch线程 F6
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//等待子线程返回 XCO8A\  
try{ "akAGa!V+  
if(bFirst) Zx7aae_{  
{ @|e we.r  
nFileLength = getFileSize(); kU.@HJ[@j  
if(nFileLength == -1) Qraa0]56  
{ #qeC)T  
System.err.println("File Length is not known!"); 6E.[F\u  
} s-~`Ao' <  
else if(nFileLength == -2) DgB;6Wl  
{ U\M9sTqo  
System.err.println("File is not access!");
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} d]N_<@tx9  
else .
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{ P!!O~P  
for(int i=0;i<nStartPos.length;i++) {CNJlr@z  
{ @a,=ApS"  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); >7~,w1t  
} W_,7hvE?"H  
for(int i=0;i<nEndPos.length-1;i++) ^66OzT8A  
{ X8A.ag0Uu  
nEndPos = nStartPos[i+1]; Mc$rsqDz  
} 1/K1e$r  
nEndPos[nEndPos.length-1] = nFileLength; GK[9IF#_>  
} dczSW]%  
} q03+FLEfC  
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1kR. .p<"  
//启动子线程 %s^1de  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]>%2,+5  
for(int i=0;i<nStartPos.length;i++) 8si{|*;hL  
{ C ,|9VH  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), B<n[yiJ}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), nHRk2l|  
nStartPos,nEndPos,i); Of-xGoYZ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); A}&YK,$5ED  
fileSplitterFetch.start(); 4=;j.=>0X  
} 62y
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !hHX8TD^J  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); t1yOAbI  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", %~8f0B|im  
nEndPos = " + nFileLength); S\Le;,
5Z  
// fileSplitterFetch[nPos.length-1].start(); lP*=4Jh  
o>bi~(H  
[IAk9B.\  
//等待子线程结束 )=MK&72r  
//int count = 0; )jg*u}u 0  
//是否结束while循环 Q w - z  
boolean breakWhile = false; "?lz[K>  

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R.Fl5B  
while(!bStop) 5h0Hk<N  
{ dUl"w`3  
write_nPos(); _Hfpizm  
Utility.sleep(500); 5`gVziS!S  
breakWhile = true; }V`_(%Q-e  
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>]C/ Q6  
for(int i=0;i<nStartPos.length;i++) CDsl)  
{ noEl+5uY  
if(!fileSplitterFetch.bDownOver) V0W4M%  
{ V\opC6*L_e  
breakWhile = false; DS>&|zF5l  
break; 9!Jt}n?!g  
} PHY!yc-LjV  
} 4;r,U{uR  
if(breakWhile) 8{ =ha  
break; ~(huU
W  
~TeOl|!lE+  
DuDt'^]  
//count++; (E&M[hH+  
//if(count>4) ,J-|.ER->  
// siteStop(); p]/[ji  
} DHx&%]r;D  
$!y^t$u$@  
kv,!"<  
System.err.println("文件下载结束！"); M_.Jmh<&&  
} "5O>egt  
catch(Exception e){e.printStackTrace ();} CR%h$+dzy  
} v+`'%E  
R5((
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vyB{35p$  
//获得文件长度 (v|<" tv  
public long getFileSize() \_6  
{ 3dLqlJ^7B  
int nFileLength = -1; +`>E_+
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try{ s/s&d pT*  
URL url = new URL(siteInfoBean.getSSiteURL()); wU<j=lY?f  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); n:) [%on  
httpConnection.setRequestProperty("User-Agent","NetFox"); 47Bg[  
+PI}$c-|`  
OVU)t]  
int responseCode=httpConnection.getResponseCode(); nvXjW@)`  
if(responseCode>=400) .=t:Uy  
{ Dq$1 j%4Y  
processErrorCode(responseCode); ~gGkw#  
return -2; //-2 represent access is error }1~9i'o%Z  
} d;wq@e  
js"5{w&  
"`cPV){]  
String sHeader; b=pk;'-  
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for(int i=1;;i++) ;' vkF  
{ 2nCc(F&+?
 
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); i8-Y,&>V  
//Utility.log(in.readLine()); G/~gF7  
sHeader=httpConnection.getHeaderFieldKey(i); >A6W^J|[  
if(sHeader!=null) wy${EY^h  
{ ilHf5$  
if(sHeader.equals("Content-Length")) L?N-uocT  
{ NCG;`B`i  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 
{6:*c
  
break; #OM)71kB8  
} X;GU#8W  
} 4;CI<&S  
else SJMbYjn0J  
break; G)t-W%D&  
} q/54=8*h0  
} `XK\', }F  
catch(IOException e){e.printStackTrace ();} l'wu-  
catch(Exception e){e.printStackTrace ();} j|K;Yi  
r<!nU&FPD:  
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Utility.log(nFileLength); j4=iHnE;  
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return nFileLength; PsXCpyY!s  
} FdzdoMY  
$,U/,XA {E  
,*d8T7T  
//保存下载信息（文件指针位置） qTdwi?j_  
private void write_nPos() { AYW C6Y  
{ F;}JSb"  
try{ -)')PV_+  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 0zSz[;A  
output.writeInt(nStartPos.length); Hv^Bw{"/R  
for(int i=0;i<nStartPos.length;i++) 6vE#$(n#a&  
{ DwGM+)!  
// output.writeLong(nPos); ./Ek+p*96H  
output.writeLong(fileSplitterFetch.nStartPos); 6o3#<ap<  
output.writeLong(fileSplitterFetch.nEndPos); RO/(Ldh  
} _80L/92  
output.close(); bEQ-?X%7  
} Xo~q
}(ze^  
catch(IOException e){e.printStackTrace ();} 0+@:f^3]!  
catch(Exception e){e.printStackTrace ();} -aok]w m  
} 6?KUS}nRS  
]YFjz/f  
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//读取保存的下载信息（文件指针位置） 4W*o:Y!  
private void read_nPos() K$/"I0YyI  
{ Fb%?qaLmCv  
try{ K|-m6!C!7  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); GPhhg  
int nCount = input.readInt(); p!^K.P1 '  
nStartPos = new long[nCount]; 8zj&e8&v  
nEndPos = new long[nCount]; U), HrI>;  
for(int i=0;i<nStartPos.length;i++) nYZ6'Iwi'  
{ Y)5O %@Rl  
nStartPos = input.readLong(); 6LGl]jHf  
nEndPos = input.readLong(); [Tbnfst  
} Sqb>aj  
input.close(); #!UJY%c~  
} pInEB6L.P  
catch(IOException e){e.printStackTrace ();} Q. O4R
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catch(Exception e){e.printStackTrace ();} (Q% @]  
} *P`wuXn}  
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private void processErrorCode(int nErrorCode) ;)CN=J!  
{ sfn^R+x4,9  
System.err.println("Error Code : " + nErrorCode); O(8CrKYY  
} u_9c>  
ui#nN  
8uLS7\,$z  
//停止文件下载 o)@nnqa  
public void siteStop() $[fqTh  
{ 8_HBcZWs  
bStop = true;
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for(int i=0;i<nStartPos.length;i++) i)X~L4gn  
fileSplitterFetch.splitterStop(); +<F3}]]  
PLs`Ci|`  
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} 7R:Ij[dV  
} y _"V=:  
//负责部分文件的抓取 ROQ]sQpk  
**FileSplitterFetch.java P<vU!`x%q  
*/ @- |G_BZ  
package NetFox; S 4 17.n  
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import java.io.*; Nr>UZlU8  
import java.net.*; L{F]uz_
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7  
public class FileSplitterFetch extends Thread { +O 7( >a  
;#v3C;  
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String sURL; //File URL C@`#@1X  
long nStartPos; //File Snippet Start Position Icg-rwa<Z  
long nEndPos; //File Snippet End Position K\U`gTGc  
int nThreadID; //Thread's ID IMqe(  
boolean bDownOver = false; //Downing is over [i
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boolean bStop = false; //Stop identical _h}(jEd!  
FileAccessI fileAccessI = null; //File Access interface *m<[ sS  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException *aCVkFp  
{ Ev
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this.sURL = sURL; [=jZP,b&),  
this.nStartPos = nStart; q%kCTw  
this.nEndPos = nEnd; Sj(>G;  
nThreadID = id; vJ'22)n
 
fileAccessI = new FileAccessI(sName,nStartPos);//定位 {*O+vtir%  
} Bv@p9 ] n  
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public void run() Z!|r>  
{ N^oP,^+U  
while(nStartPos < nEndPos && !bStop) P`Ku. ONQ  
{ Fh)xm* u(  
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try{ j`.&4.7+  
URL url = new URL(sURL); B;=Z^$%T  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }a5TY("d9H  
httpConnection.setRequestProperty("User-Agent","NetFox"); y<- ]'Yts  
String sProperty = "bytes="+nStartPos+"-"; dNt^lx  
httpConnection.setRequestProperty("RANGE",sProperty); vkGF_aenk  
Utility.log(sProperty); ms}o[Z@n  
\X*y~)+K`  
">wvd*w0"(  
InputStream input = httpConnection.getInputStream(); e7xv~C>g  
//logResponseHead(httpConnection); o}KVT%}  
w@,p`  
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byte[] b = new byte[1024]; 7!jb  
int nRead; v0)Y,hW  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) QlMLWi  
{  ]aF;  
nStartPos += fileAccessI.write(b,0,nRead); >@ 8'C"F  
//if(nThreadID == 1) PsNrCe%e  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); r4iNX+h?V  
} GV1Ol^  
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de W1>yh^_  
Utility.log("Thread " + nThreadID + " is over!"); ]FVJQS2h  
bDownOver = true; )YEAk@h@  
//nPos = fileAccessI.write (b,0,nRead); W>w(|3\  
} (N&?
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catch(Exception e){e.printStackTrace ();} +?"F=.SZ  
} KQ]sUNH  
} ZXb{-b?[`  
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)HE{`yiLL  
//打印回应的头信息 TX$dxHSPK  
public void logResponseHead(HttpURLConnection con) u=qK_$d4  
{ )m =xf1  
for(int i=1;;i++) y$-@|M$GG  
{ ?eX$Wc{  
String header=con.getHeaderFieldKey(i); AeEdqX)  
if(header!=null) 71[?AmxV  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); @u/CNx,`X  
Utility.log(header+" : "+con.getHeaderField(header)); 9;{(.K  
else c8mh
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break; .gC.T`/m  
} iLBORT!;  
} &)Qq%\EP4  
#OM'2@  
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public void splitterStop() P2jh[a%  
{ dcmf~+T  
bStop = true; #|je m   
} $6UU58>n  
; ,sNRES3  
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} %(&ja_oO  
8~Zw"  
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/* O(%6/r`L,k  
**FileAccess.java 3\P*"65  
*//文件访问(定位，写) K5LJx-x*j  
package NetFox; ?'f  
import java.io.*; b3>zdS]Q  
]\|2=  
n7;jME/!  
public class FileAccessI implements Serializable{ V0>[bzI  
D['J4B  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 )s:kQ~+  
RandomAccessFile oSavedFile; |0}Xb|+  
long nPos; T\p>wiY2|F  
`!N}u  
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public FileAccessI() throws IOException R3og]=uFzm  
{ AC <2.i_  
this("",0); 7NT} Zwf  
} s|XWw<Sa  
(Ox&B+\v+v  
@:CM<+  
public FileAccessI(String sName,long nPos) throws IOException B6&[_cht  
{ ~x9J&*zxM  
oSavedFile = new RandomAccessFile(sName,"rw"); 1o\2\B=k{  
this.nPos = nPos; Heh&;c  
oSavedFile.seek(nPos); Jy}~ZY  
} h9m|f|cH  
c"kB@P  
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public synchronized int write(byte[] b,int nStart,int nLen) c.LRS$o/j  
{ /dg?6XT/  
int n = -1; Rkk`+0K7$J  
try{ j~\FDcG*ed  
oSavedFile.write(b,nStart,nLen); H?;+C/-K`_  
n = nLen; dpS@:  
} >H;m[  
catch(IOException e) tx[;& ;  
{ _I;hM  
e.printStackTrace (); \,/ozfJ7dT  
} rG~W=!bj  
B=]L%~xL$  
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return n; (Q||
5  
} ejR$N!LL  
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} ] H;E(1iU  
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NVkYm+J#  
/* 6<\dQ+~  
**SiteInfoBean.java rMJ@oc  
*/ ~.^:?yCA  
package NetFox; m=E/um[D  
:kI[Pf!z  
X4:84  
public class SiteInfoBean { rU9")4sQ  
PO'K?hVS^w  
lGp:rw`
 
private String sSiteURL; //Site's URL {~51h}>b#  
private String sFilePath; //Saved File's Path L''VBY"?  
private String sFileName; //Saved File's Name ={cM6F}a@  
private int nSplitter; //Count of Splited Downloading File CZ]Dm4  
l[5** ?#  
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public SiteInfoBean() MwQtf(_  
{//nSplitter的缺省值为5 NMw5ixl  
//default value of nSplitter is 5 @eBo7#Zr  
this("","","",5); \M.?*p  
} 4Yok,<  
dbEXlm  
-}T7F+  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ]6v7iuvI  
{ xv$fw>  
sSiteURL= sURL; @(=?x:j  
sFilePath = sPath; qOpwl*?x+  
sFileName = sName; tOnOzD  
this.nSplitter = nSpiltter; /KnIU|;  
)ZLj2H<  
g$)0E<  
} _+)
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public String getSSiteURL() g8Y)90 G  
{ 6w3[PNd  
return sSiteURL; 3_;=y\F  
} `xv Uq\  
>J;J&]Olf  
lws.;abm%n  
public void setSSiteURL(String value) !}P^O(oY  
{ [m< jM[w{  
sSiteURL = value; [W[awGf  
} B(71I;  
|uFb(kL[U  
l#ct;KZ  
public String getSFilePath() J Z@sk2  
{ UjunIKX+  
return sFilePath; bSI*`Dc"!  
} G DBV  
t`}=~/#`X  
!7]^QdBLY  
public void setSFilePath(String value) ?t\GHQ$$?  
{ h^IizrqU  
sFilePath = value; Qt'3v"S>)  
} Tp~Qg{%Og  
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[=.iJ5,{2  
public String getSFileName() 1GR|$E  
{ FR50y+h^$  
return sFileName; 9P <1/W!  
} Wkb>JnPo  
~9!@BL\  
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public void setSFileName(String value) AxJqLSfyb,  
{ HWou&<EK  
sFileName = value; Xsb.xxK.  
} (Y&gse1}!  
;gJAxVD<  
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public int getNSplitter() P%w!4v~"  
{ |,.1=|&u  
return nSplitter; ~|{e"!(}  
} 6eB~S)Ko  
V.Lk70 \  
@Py'SH!-  
public void setNSplitter(int nCount) I)%bOK]  
{ [ot+EA  
nSplitter = nCount; 4yMi9Ri4H  
} 5``usn/&Kj  
} vsA/iH.  
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%AT/g&M&1#  
/* ,HE{&p2y  
**Utility.java DeN2P  
*/ ~:C`e4  
package NetFox; 7we='L&R  
:%fnJg(
 
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public class Utility {  HsG3s?*  
44^jE{,9  
] :](xW%  
public Utility() qw|B-lT{:  
{ n%vmo f  
*&_(kq z'1  
|U~\;m@  
} &u2m6 r>W  
r5lPO*?Df  
//线程睡眠 u8x#XESR7  
public static void sleep(int nSecond) n?^oQX}.\  
{ +WxD=|p;  
try{ UY\E uA9  
Thread.sleep(nSecond); uqBVKE  
} wUS w9xg  
catch(Exception e) _>t6]?*  
{ ?|hYtV  
e.printStackTrace (); a}k5[)et  
} )DQcf]I  
} >\lBbqa#  
JVx-4?  
//日志 [;C*9Nl  
public static void log(String sMsg)  </Dv?  
{ p@YbIn  
System.err.println(sMsg);
!|,djo!N  
} >bwq  
@# p{,L  
%x^U3"7  
public static void log(int sMsg) 6I5LZ^/G9  
{ 0bQ"s*K  
System.err.println(sMsg); `4|:8@,3{  
} |)ALJJ=+  
} S]c&T`jx  
Fy^8]u*Fu  
ir;az{T#U  
/* Ez^wK~  
**TestMethod.java N/B-u
)?\:  
*/ R8, g^N  
package NetFox; V9D>Xh!0H  
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public class TestMethod { eyByAT~W,  
#ChF{mh  
Gd[:&h  
public TestMethod() jxgs!B>  
{ ///xx/weblogic60b2_win.exe ?$H=n{iW  
try{ J}VG4}L  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Yc>.P  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); `Y<FR  
SiteFileFetch fileFetch = new SiteFileFetch(bean); mx0EE
U*  
fileFetch.start(); 8/CK(G  
} @B>pPCowa  
catch(Exception e){e.printStackTrace ();} GUvEOD=p  
E$5A 1  
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} T5TAkEVl  
+78cQqDY!  
=?1B|hdo  
public static void main(String[] args) ";w"dfC^  
{ (5=B^9{R  
new TestMethod(); {=T9_c  
} 843O}v'  
} lMb&F[KJ7  
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