http断点续传简单实现（java)

/*
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**SiteFileFetch.java ; ^$RG
  
*/ 0C7"*H0R  
package NetFox; #wo_  
import java.io.*; 9we=aX5  
import java.net.*; 'fB`e]_  
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4 qnQF]4  
public class SiteFileFetch extends Thread { #\jPBLc  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 1{wy%|H\  
long[] nStartPos; //开始位置 e'ZgF~  
long[] nEndPos; //结束位置 5mV'k"Om#"  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Ii9vA ^53  
long nFileLength; //文件长度 8dpVB#]pp,  
boolean bFirst = true; //是否第一次取文件 /; _"A)0  
boolean bStop = false; //停止标志 QEVjXJOt0  
File tmpFile; //文件下载的临时信息 ^'h~#7s  
DataOutputStream output; //输出到文件的输出流 Pk,^q8;  
5!Guf?i  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） o%dtf5}(,  
public SiteFileFetch(SiteInfoBean bean) throws IOException xj}N;FWo  
{ u0x\5!?2  
siteInfoBean = bean; B
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); <sTaXaq?  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); \h yTcFb  
if(tmpFile.exists ()) !87ebo  
{ cz0tnF*&  
bFirst = false; >#'6jm
 
read_nPos(); b/ynCf8X  
} bi5'-.B  
else u&<L
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{ iZ58;`  
nStartPos = new long[bean.getNSplitter()]; ZpZ~[BtQ  
nEndPos = new long[bean.getNSplitter()]; mdk:
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} ^^[,aBu  
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} tpVtbh1)u  
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public void run() =?}'\ >G "  
{ [fb-G5x  
//获得文件长度 :!|xg!|y  
//分割文件 ^!}lA9\gY  
//实例FileSplitterFetch iX,Qh2(ig  
//启动FileSplitterFetch线程 Lt*H|9  
//等待子线程返回 Ah"RxA  
try{ j/W#=\xz  
if(bFirst) f(3#5288  
{ &38Fj'l  
nFileLength = getFileSize(); lmod8B  
if(nFileLength == -1) 3:C *'@  
{ MXhS\vF#m  
System.err.println("File Length is not known!"); 9|go`^*.  
} /E*P0y~KTW  
else if(nFileLength == -2) )~Q$ tM`  
{ TKm
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System.err.println("File is not access!"); UqAvFCy  
} w0.#/6  
else 0D\FFfs  
{ f[z#
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for(int i=0;i<nStartPos.length;i++) 3U}z?gP[  
{ CfVz'  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); {d3r>Ub)7d  
} =\q3;5[  
for(int i=0;i<nEndPos.length-1;i++) rsIjpPa  
{ 1mB6rp  
nEndPos = nStartPos[i+1]; U$-FQRM4K  
} lKm?Xu'yH  
nEndPos[nEndPos.length-1] = nFileLength; osnDW aN  
} 0wc+<CUW  
} t%/5$<!b  
:]]amziP&  
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//启动子线程 vzVl2  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 6h5*b8LxA  
for(int i=0;i<nStartPos.length;i++) *zmbo >{(  
{ 2;q6~Y,  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), D6 M:pIN*  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), f[X>?{q  
nStartPos,nEndPos,i); EswM#D9(4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [6c{t  
fileSplitterFetch.start(); >si
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} 2Aff3]-:Gd  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), <|.M]]}j  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); kQj8;LU  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", H6~QSe0l  
nEndPos = " + nFileLength); alq>|,\x  
// fileSplitterFetch[nPos.length-1].start(); v7g-M  
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//等待子线程结束 8sL7p4  
//int count = 0; 04,]upC${W  
//是否结束while循环 Hiw{1E:rW  
boolean breakWhile = false; )`L!eN  
rMI:zFS  
zJ#q*2A(Z  
while(!bStop) ."MBKyg6  
{ f}@]dFr  
write_nPos(); '&U
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Utility.sleep(500); xOS4J+'s@  
breakWhile = true; vuD tEz  
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for(int i=0;i<nStartPos.length;i++) i8dv|oa  
{ 51L:%Af  
if(!fileSplitterFetch.bDownOver) Fn6>n04v  
{ ]0\8g=KK  
breakWhile = false; }J:~}?^%n  
break; TG'A'wXxy  
} Mj[v _&N  
} Vj`9j. 5  
if(breakWhile) A/GEDG ?  
break; Ll&Y_Ry  
&L+u]&!6C  
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//count++; [<bfwTFsl  
//if(count>4)  M)Y`u  
// siteStop(); jH\@Oc;7  
} y_\vXY'  
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System.err.println("文件下载结束！"); , Lhgv1  
} KeY)%{  
catch(Exception e){e.printStackTrace ();} ;Q-(tGd  
} lO)
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;clF\K>  
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//获得文件长度 c7S<ex,  
public long getFileSize() lshO'I+)*  
{ |f.=Y~aY  
int nFileLength = -1; S+_}=25  
try{ ll73}v  
URL url = new URL(siteInfoBean.getSSiteURL()); .-fJ\`^mi  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ^D"}OQoh  
httpConnection.setRequestProperty("User-Agent","NetFox"); J*qepq`_  
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int responseCode=httpConnection.getResponseCode(); JYs*1
<  
if(responseCode>=400) NC|&7qQ  
{ |$^,e%bE  
processErrorCode(responseCode); 1u'x|Un  
return -2; //-2 represent access is error l8n#sGA%  
} ]g!k'@  
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}[$C=|>  
String sHeader; 5c`DkWne%  
% ;09J  
8kX3.X`  
for(int i=1;;i++) ct fKxGH  
{ DSD#',  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); \snbU'lfP  
//Utility.log(in.readLine()); :>;-uve8'  
sHeader=httpConnection.getHeaderFieldKey(i); /w`{]Ntgu  
if(sHeader!=null) C KBLM2D  
{ kjJ\7x6M  
if(sHeader.equals("Content-Length"))
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{ i8+kc_8#d  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); u3w `(3{<  
break; 9T`xW]Zf  
} L*Xn!d%  
} CSR6  
else mRxL%!  
break; qXCl6Yo8  
} YNH>^cD1  
} V :*GG+4  
catch(IOException e){e.printStackTrace ();} 's(0>i  
catch(Exception e){e.printStackTrace ();} X_
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Utility.log(nFileLength); ZZ)bTLu  
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return nFileLength; :DR G=-M  
} dPPe_% Ilr  
3-FS} {,  
,iB)8Km@U  
//保存下载信息（文件指针位置） -P!vCf^{ t  
private void write_nPos() 2sk^A ly  
{ [yf2_{*0T  
try{ XCDHd ?Ld  
output = new DataOutputStream(new FileOutputStream(tmpFile)); P (_:8|E  
output.writeInt(nStartPos.length); Z
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for(int i=0;i<nStartPos.length;i++) *;1G+Q#  
{ axxdW)+K  
// output.writeLong(nPos); A!ba_14  
output.writeLong(fileSplitterFetch.nStartPos); ]9]3=;b>  
output.writeLong(fileSplitterFetch.nEndPos);  N_=7  
} #Z"N\49  
output.close(); ACU0  
}  /e!/  
catch(IOException e){e.printStackTrace ();} mO?G[?*
\  
catch(Exception e){e.printStackTrace ();} tv,^ Q}  
} d9R0P2  
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//读取保存的下载信息（文件指针位置） w-HgC  
private void read_nPos() ~lzV=c$t  
{ pW:U|m1dS  
try{ KJ.ra\F  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); `i9WnPRt  
int nCount = input.readInt(); 2Qc&6-;`  
nStartPos = new long[nCount]; SrN0f0  
nEndPos = new long[nCount]; %$:js4  
for(int i=0;i<nStartPos.length;i++) Ni"fV]'  
{ W7O%.xP  
nStartPos = input.readLong(); #:"\6s  
nEndPos = input.readLong(); s3uT:Xw3rW  
} `g6Z
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input.close(); /?9e{,\s  
} A&Ut:OiA  
catch(IOException e){e.printStackTrace ();} '4L i  
catch(Exception e){e.printStackTrace ();} \@*cj8e  
} RIC'JLWQ  
9 /t}S6b{  
66[yL(*+  
private void processErrorCode(int nErrorCode) nR!qolh  
{ ) ok_"wB  
System.err.println("Error Code : " + nErrorCode); tJ&S&[}  
} Zdr +{-  
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//停止文件下载 5\S)8j `8  
public void siteStop() RD=
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{ wAVO%8u  
bStop = true; OJbY\U  
for(int i=0;i<nStartPos.length;i++) t1n'
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fileSplitterFetch.splitterStop(); l!~8  
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} f|m.v +7k  
} fx99@%Ii  
//负责部分文件的抓取 2^[fUzL?  
**FileSplitterFetch.java |uj1T=ZY  
*/ yJ/m21f  
package NetFox; ;}.jRmnJ  
<*8nv.PX*  
~ W52Mbf  
import java.io.*; (J\D"4q  
import java.net.*; L)y}  
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public class FileSplitterFetch extends Thread { *h@nAB\3  
h'MX{Wm.  
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String sURL; //File URL v;JY;Uh|  
long nStartPos; //File Snippet Start Position %
nFZA)B[  
long nEndPos; //File Snippet End Position H+zQz8zMC  
int nThreadID; //Thread's ID ;=_<\2  
boolean bDownOver = false; //Downing is over vkc(-n  
boolean bStop = false; //Stop identical X H{5E4P  
FileAccessI fileAccessI = null; //File Access interface p KKn  
v:JFUn}  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Wj8\~B=('  
{ Z TjlGU `  
this.sURL = sURL; &y3_>!L  
this.nStartPos = nStart; |I)MsNF  
this.nEndPos = nEnd; @U}fvdft  
nThreadID = id; ]L}<Y9)t  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 a[lE9JA;|  
} F]M3/M  
q'C'S#qqn  
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public void run() =1VY/sv  
{ 1?E\2t&K  
while(nStartPos < nEndPos && !bStop) goRoi\z $  
{ r/:9j(yxr  
:d)@|SR1  
}..}]J;To  
try{ D dt9`j  
URL url = new URL(sURL); 2>ce(4Gky  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 5C#&vYnq  
httpConnection.setRequestProperty("User-Agent","NetFox"); GrVvOJr  
String sProperty = "bytes="+nStartPos+"-"; :L*CL 8m  
httpConnection.setRequestProperty("RANGE",sProperty); sJ3HH0e  
Utility.log(sProperty); Q1buuF#CU&  
>]ZojdOl)  
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InputStream input = httpConnection.getInputStream(); |\~cjPX(  
//logResponseHead(httpConnection); $sGX%u  
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2s|[!:L5  
byte[] b = new byte[1024]; u^!-Z)W  
int nRead; /x0zZ+}V  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Yw?%>L  
{ 0sV;TQt+f  
nStartPos += fileAccessI.write(b,0,nRead); jUW{Z@{U  
//if(nThreadID == 1) ]E[Mv} =  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); #G)ZhgB^  
} -qid.  
rIS \#j  
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Utility.log("Thread " + nThreadID + " is over!"); PuUqWW'^  
bDownOver = true; oVc_(NH-  
//nPos = fileAccessI.write (b,0,nRead); k\HRG@ /G  
} zzq/%jki  
catch(Exception e){e.printStackTrace ();} JK[7&C-O  
} a)y8MGx?  
} G>*s+  
Er~5\9,/<]  
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//打印回应的头信息 'T+3tGCy+  
public void logResponseHead(HttpURLConnection con) O3Ks|%1  
{ z@T;N'EM  
for(int i=1;;i++) TtkB  
{ Z{u*vUC&  
String header=con.getHeaderFieldKey(i); Jw;J$ u!d  
if(header!=null) S`"IM?  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); X} 8rrC=  
Utility.log(header+" : "+con.getHeaderField(header)); >MiA|N=  
else *K-,<hJ#L  
break; rpDH>Hzq  
} D&Ngg)_Mq  
} F?5kl/("  
3smcCQA%  
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public void splitterStop() .`xcR]PQ  
{ YBHmd  
bStop = true; K _O3DcQ  
} #l8CUg~Uj  
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} ];zi3oS^  
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/* fwXk{P/  
**FileAccess.java cZ^$!0  
*//文件访问(定位，写) 0+cRUH9Ew  
package NetFox; TZ-n)rC)v  
import java.io.*; +>c)5Jih  
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UmInAH4  
public class FileAccessI implements Serializable{ q'q'v S  
fN8A'p[  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 AB}Q
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RandomAccessFile oSavedFile; #r:J,D6*   
long nPos; \p [!@d^  
*R1x^t+)  
* Oyic3F  
public FileAccessI() throws IOException 49HtI9@  
{ URJ"  
this("",0); @oYTJd(v{  
} BjOrQAO  
-"!V&M  
fgTvwOSk  
public FileAccessI(String sName,long nPos) throws IOException Tff7SEP  
{ hMhD(X  
oSavedFile = new RandomAccessFile(sName,"rw"); YM+}Mmu  
this.nPos = nPos; YN"102CK  
oSavedFile.seek(nPos); 2/?pI/W  
} x1mxM#ql  
C2ToT\^  
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public synchronized int write(byte[] b,int nStart,int nLen) Mr/^V,rA  
{ >G/>:wwSP.  
int n = -1; &v3r#$Hj[  
try{ 988aF/c  
oSavedFile.write(b,nStart,nLen); `d3S0N6@  
n = nLen; g<}EL[9  
} ;#fB=[vl";  
catch(IOException e) gEU)UIJ  
{ 6sB!m|zm]:  
e.printStackTrace (); pN4!*7M  
} "%A[%7LY  
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return n; ?R"5 .3  
} SuGlNp>#qm  
A(;J  
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} z?1G
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$_)YrqSo~  
/* n'4D;4  
**SiteInfoBean.java |[k6X=5  
*/ X] Tb4  
package NetFox; T7cT4PAW  
\mWXr*;  
S)JZb_  
public class SiteInfoBean { jcx/ZR  
>`,v?<>+  
t#Yyo$9  
private String sSiteURL; //Site's URL iVXR=A\er  
private String sFilePath; //Saved File's Path WMh'<'wN_  
private String sFileName; //Saved File's Name 0Xk;X1Xl  
private int nSplitter; //Count of Splited Downloading File w[4SuD  
\2eYw.I=  
}})4S
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public SiteInfoBean() 8 _`Lx_R  
{//nSplitter的缺省值为5 ?:n{GK  
//default value of nSplitter is 5 tGM)"u-  
this("","","",5); Vy-S9=  
} P]dDTh~e~  
iP'}eQn]c  
\4zvknk<  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) r]0o  
{ *xL#1  
sSiteURL= sURL; r\=p.cw<  
sFilePath = sPath; y7,~7f!N2  
sFileName = sName; =Ee
f  
this.nSplitter = nSpiltter; u!L8Sv  
PO)5L  
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} F<IqKgGz
H  
]V.9jlXF  
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public String getSSiteURL() ax7 M  
{ Z.<1,EKi=  
return sSiteURL; z^B!-FcIz>  
} ;]nU->  
@&EE/j^  
3
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public void setSSiteURL(String value) 66Hu<3X P  
{ hih`:y  
sSiteURL = value; wJ IJPYTK  
} #+ n &  
_}JygOew  
ZTt%7K"L  
public String getSFilePath() ,FBF;zED  
{ /=7|FtB`  
return sFilePath; WNL3
+  
} !lu$WJ{M  
*q8W;WaL  
rZpc"<U  
public void setSFilePath(String value) 06Uxd\E~  
{ If4YqBG  
sFilePath = value;
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} o_\b{<^I  
]/d2*#  
Ii[rM/sG  
public String getSFileName() VK`b'U&l"  
{ ?hDEFW9&^x  
return sFileName; /9GqEQsf
M  
} d5zzQ]|L  
vZ|-VvG  

4r5,kOFWb  
public void setSFileName(String value) ao7|8[  
{ \uanQ|Nu  
sFileName = value; MX9q )(:  
} Bq:@ [pCQ  
lfI[
r|  
0/] @#G2  
public int getNSplitter() 7Uj[0Awn  
{ BY\p?79  
return nSplitter; $X\BO&  
} Ir}&|"~H
 
=20Q!wcu  
46e;UUf!d  
public void setNSplitter(int nCount) ;W+.]_$6)T  
{ 
/!%P7F  
nSplitter = nCount; EG9S? $  
} T>?sPq  
} }.T$bj1B;V  
Box,N5AA  
VUNQ@{ST|1  
/* Fg,[=CqB[  
**Utility.java N!Y'W)i16  
*/ :fj}J)9'xW  
package NetFox; |]m&LC  
I1}{7-_t  
txL5'mK  
public class Utility { X=.+XP]  
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N  
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public Utility() oW
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{ pP".?|n  
h hdn9n  
k| jCc  
} cF/FretoO  
%NAz(B  
//线程睡眠 _;@kS<\N  
public static void sleep(int nSecond) RcHyePuF)R  
{ U}qW9X;o  
try{ "0/OpT7h7  
Thread.sleep(nSecond); Stp??  
} Z-vzq;  
catch(Exception e) G
! 87F/  
{ NGxii$F  
e.printStackTrace (); zD?$O7 |ZK  
} 5T;_k'qe  
} YTGup]d  
}~ +  
//日志 {{ wVM:1  
public static void log(String sMsg) YobIbpo  
{ ]#*@<T*[  
System.err.println(sMsg); @FbzKHd
V/  
} o86}NqK  
l"cO@.T3  
Z,d/FC#y(  
public static void log(int sMsg) .z{7 rH  
{ ]&9f:5',  
System.err.println(sMsg); RL&*.r&  
} }U#S*  
} ;pULJ}rDb  
o?%x!m>  
(te\!$  
/* z.jGVF4  
**TestMethod.java 3s|tS2^4  
*/ P,v}Au( UI  
package NetFox; 6?KsH;L9  
", |wG7N K  
nTHP~]  
public class TestMethod { r1=Zoxc=w  
g`Rs;  
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public TestMethod() a;h:o>Do5  
{ ///xx/weblogic60b2_win.exe ~ h:^Q  
try{ w6cPd'  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); '@:;oe@]  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); vw(};)8  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 2.NzB7c*CM  
fileFetch.start(); oZ8SEC"]  
} +(P;4ZOmB  
catch(Exception e){e.printStackTrace ();} PuOo^pFhH  
|Jq/kmn  
Dnp^yqz*  
} .oe,#1Qh{  
zO+nEsf^O  
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public static void main(String[] args) \{&55>  
{
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new TestMethod(); HK-?<$Yc  
} $rlIJwqn  
} :J<S-d=  
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