http断点续传简单实现（java)

/* K:!"+q  
**SiteFileFetch.java (^s>m,h  
*/ <L`KzaA  
package NetFox; AB=daie  
import java.io.*; ->sm+H-*  
import java.net.*; (gy#js#  
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public class SiteFileFetch extends Thread { o1Ph~|s*8  
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SiteInfoBean siteInfoBean = null; //文件信息Bean =5Q]m6-SgV  
long[] nStartPos; //开始位置 O?)3VT*  
long[] nEndPos; //结束位置 kB3H="3[[  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 4NGA/ G  
long nFileLength; //文件长度 |y&*MTfV4L  
boolean bFirst = true; //是否第一次取文件 ?6Jx@Sh  
boolean bStop = false; //停止标志 ~5_Ad\n9  
File tmpFile; //文件下载的临时信息 Q?e*4ba  
DataOutputStream output; //输出到文件的输出流 !6BW@GeF]  
9XPo3;  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） :e]a$  
public SiteFileFetch(SiteInfoBean bean) throws IOException 5Y.vJz  
{ vtw6FX_B  
siteInfoBean = bean; t\NqR  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); iJ~Zkd  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ZNf6;%oGG  
if(tmpFile.exists ()) kgnmGuka  
{ }
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bFirst = false; >xF/Pl  
read_nPos(); )Gj8X}DM  
} }2<r,  
else N"8_S0=pw  
{ 9F4Dm*_<  
nStartPos = new long[bean.getNSplitter()]; |zR8rqBX;  
nEndPos = new long[bean.getNSplitter()]; 9^,Lc1"M>  
} T.@aep\"  
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} #bMuvaP~  
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public void run() &0NFb^8+  
{ LNrX;{ Z  
//获得文件长度 BnCbon)  
//分割文件 w9NHk~LHKF  
//实例FileSplitterFetch 0/!dUWdKH  
//启动FileSplitterFetch线程 @n(Z$)8tR  
//等待子线程返回 -M[$Zy^  
try{ )#.<]&P}  
if(bFirst) Gs9:6  
{ (@t(?Js  
nFileLength = getFileSize(); J13>i7]L%  
if(nFileLength == -1) /x5rf  
{ : y5<go8e  
System.err.println("File Length is not known!"); *8#i$w11M  
} T(e!_VY|m  
else if(nFileLength == -2) rypTKT|U;  
{ @$LWWTr;  
System.err.println("File is not access!"); |_`E1Y}}  
} Eve.QAl|  
else iTag+G4*  
{ JS*m65e  
for(int i=0;i<nStartPos.length;i++) 89\n;5'f4  
{ Z$0uH*h  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Svc|0Ad&  
} '[C.|)"  
for(int i=0;i<nEndPos.length-1;i++) J]&y$?C  
{ `t_W2y
  
nEndPos = nStartPos[i+1]; T9]HGB{  
} E_8\f_%wK  
nEndPos[nEndPos.length-1] = nFileLength; qQ"Fv|]~>  
} cfcim.jB  
} COW}o~3-4  
dl~%MWAVb  
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//启动子线程 +m8!U=Zi  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ow_djv:,  
for(int i=0;i<nStartPos.length;i++) A
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{ B>GE9y5  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ADpmvW f?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), "FTfk  
nStartPos,nEndPos,i); 9(6I<]#  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Td G!&:>  
fileSplitterFetch.start(); agjv{  
} u
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6xZ=^;H  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); czm&~n6$  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ",
(cN}Epi(D  
nEndPos = " + nFileLength); df n9!h  
// fileSplitterFetch[nPos.length-1].start(); wg0 \_@3  
nWMmna.5  
K91)qI;BD  
//等待子线程结束 ,:??P1  
//int count = 0; xo&]RYG[<  
//是否结束while循环 (HSgEs1d  
boolean breakWhile = false; 5g9; +}X;  
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}  
while(!bStop) t`+'r}=d  
{ * 1Od-3  
write_nPos(); t 0-(U\  
Utility.sleep(500); [+OnV&  
breakWhile = true; gS:A'@&  
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XK: 9r{r{  
for(int i=0;i<nStartPos.length;i++) ~_s{0g]B  
{ G 2mX;  
if(!fileSplitterFetch.bDownOver) SF5@Vg  
{ dlG=Vq&Y  
breakWhile = false; X+~ XJ  
break; bzvh%RsW  
} .VkbYK  
} C#H:-Q&  
if(breakWhile) me'd6!O9-  
break; &[At`Nw71  
#hlCs  
8X I?  
//count++; 4WE6fJ2X  
//if(count>4) PI*82,f3dE  
// siteStop(); Rcawc Y  
} cetvQAGXY  
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System.err.println("文件下载结束！"); NuYkz"O]  
} 6:]*c[7  
catch(Exception e){e.printStackTrace ();} P<Zh XN'  
} W$'R}L  
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//获得文件长度 +z9gbcx  
public long getFileSize() 3mSXWl^?  
{ @?[1_g_'P  
int nFileLength = -1; g/&T[FOr  
try{ 0x9x@gF  
URL url = new URL(siteInfoBean.getSSiteURL()); )NO<s0?&  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); -kS~xVS|  
httpConnection.setRequestProperty("User-Agent","NetFox"); zz^F k&  
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int responseCode=httpConnection.getResponseCode(); ?X-)J=XG  
if(responseCode>=400) $46{<4.  
{ !I\!;b  
processErrorCode(responseCode); .^bft P\  
return -2; //-2 represent access is error a"av#Y  
} <jS~ WI@  
#eN{!Niy&U  
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String sHeader; .0G6flD   
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for(int i=1;;i++) [I:KpAd/  
{
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); IG?'zppjd6  
//Utility.log(in.readLine()); ZvGgmLN  
sHeader=httpConnection.getHeaderFieldKey(i); {u[V{XIUh  
if(sHeader!=null) lc6iKFyG  
{ 1shBY@mlq  
if(sHeader.equals("Content-Length")) x"4} isp<  
{ + <c^=&7Lq  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); E(Rh#+]Y5  
break; `imWc"'Ej  
} CU:o*;jP  
} AOp/d(vx5i  
else N4K8 u'f^  
break; "7d-z<^n  
} *[eL~oN.c  
} `d2,*KR  
catch(IOException e){e.printStackTrace ();} ?4G|+yby  
catch(Exception e){e.printStackTrace ();} 65,(4Udz!  
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/?/#B `  
Utility.log(nFileLength); GO! uwo:  
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!5}l&7:(MN  
return nFileLength; xKOq[d/8  
} k;dXOn  
/cFzotr"9  
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//保存下载信息（文件指针位置） X
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private void write_nPos() 02AI%OOH  
{ kJs^ z  
try{ hbOnlj4  
output = new DataOutputStream(new FileOutputStream(tmpFile)); MVCl.o  
output.writeInt(nStartPos.length); '[P}&<ie,  
for(int i=0;i<nStartPos.length;i++) Z<b"`ty.  
{ ']ood!  
// output.writeLong(nPos); ^]p  
output.writeLong(fileSplitterFetch.nStartPos); -m 5}#P89  
output.writeLong(fileSplitterFetch.nEndPos); @LD6:gy  
} %bb~Y"  
output.close(); &ogt2<1W  
} fn{S "33"  
catch(IOException e){e.printStackTrace ();} P}3}ek1Ax  
catch(Exception e){e.printStackTrace ();} *j)M]  
} JbQZ!+  
$<?X7n^  
vC/[^  
//读取保存的下载信息（文件指针位置） 7_KhV  
private void read_nPos() "u')g&   
{ #$'"cfRxc  
try{ ek-!b!iI  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); D>T],3U(H  
int nCount = input.readInt(); bNzqls$  
nStartPos = new long[nCount]; #'o7x'n^  
nEndPos = new long[nCount]; wod/&!)]A  
for(int i=0;i<nStartPos.length;i++) FY;+PY@I{  
{ uf)Oy7FQ  
nStartPos = input.readLong(); nZvU'k:  
nEndPos = input.readLong(); V/#v\*JHFc  
} ( 76{2  
input.close(); 4B O %{  
} (RF>s.B<  
catch(IOException e){e.printStackTrace ();} DR+,Y2!_GT  
catch(Exception e){e.printStackTrace ();} 7t(Y;4<2  
} E)'8U
 
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~  
private void processErrorCode(int nErrorCode) #+sF`qR,  
{ 8cr NOZS6  
System.err.println("Error Code : " + nErrorCode); Z^6#4Q]YC  
} 3B18dv,V  
}ymvC  
w6,*9(;$Pk  
//停止文件下载 :k"rhI  
public void siteStop() N=ifIVc  
{ xUj2]Q>R+  
bStop = true; ,nE&Me&#J  
for(int i=0;i<nStartPos.length;i++) (wL3 +  
fileSplitterFetch.splitterStop(); hLA;Bl  
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} V/H@vKN2  
} cF.mb*$K  
//负责部分文件的抓取 _g6wQdxT  
**FileSplitterFetch.java 5~xeO@%I  
*/ ^CQ1I0  
package NetFox; r{"uv=,`  

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|!b9b(_j9  
import java.io.*; aJ-}  
import java.net.*; F$ {4X /9n  
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public class FileSplitterFetch extends Thread { x(6vh2#vD  
3/tJDb5  
%c0z)R~  
String sURL; //File URL C9Wojo.  
long nStartPos; //File Snippet Start Position *f*f&l%  
long nEndPos; //File Snippet End Position *R!]47Y d  
int nThreadID; //Thread's ID bA+[{  
boolean bDownOver = false; //Downing is over pX]21&F  
boolean bStop = false; //Stop identical >Fh#DmQ  
FileAccessI fileAccessI = null; //File Access interface [D9
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I  
Qg{WMlyOP  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException @ay|]w  
{ y{;u@o?T  
this.sURL = sURL; yjv&4pIc1  
this.nStartPos = nStart; dk4D+*R  
this.nEndPos = nEnd; ,Z4^'1{D  
nThreadID = id; JP_kQ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 uf?b%:A  
} >DS}#'N4l  
N.n1<  
Y`=z.D{  
public void run() wJ(8}eI  
{ w?/f Zx  
while(nStartPos < nEndPos && !bStop) "<T ~jk"u  
{ \086O9  
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try{ >OTl2F}4 !  
URL url = new URL(sURL); V:QdQ;c  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 8LeKwb  
httpConnection.setRequestProperty("User-Agent","NetFox"); ^K/G5  
String sProperty = "bytes="+nStartPos+"-"; vQcUaPm\$  
httpConnection.setRequestProperty("RANGE",sProperty); `+Xe'ey  
Utility.log(sProperty); 0hb/`[Q  

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AO^]>/7ed  
InputStream input = httpConnection.getInputStream(); cL ae=N  
//logResponseHead(httpConnection); 9G+y.^/6  
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byte[] b = new byte[1024]; J/= +r0c  
int nRead; 2>ys2:z  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) !4_!J (q%  
{ 22PGWSQ  
nStartPos += fileAccessI.write(b,0,nRead); aDXpkG0E  
//if(nThreadID == 1) d`UF0T  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); SC]6F
*  
} nQ!N}5[z'  
fHLFeSfH  
7Onk!NH  
Utility.log("Thread " + nThreadID + " is over!"); f<^ScFVR  
bDownOver = true; eS* *L3  
//nPos = fileAccessI.write (b,0,nRead); oy`3r5g  
} }Z^FEd"y  
catch(Exception e){e.printStackTrace ();} 9x4wk*z  
} cxL,]27Bu  
} #&}%70R)  
Vn@A]Jx^  
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//打印回应的头信息 vY4WQbz(  
public void logResponseHead(HttpURLConnection con) pb~Ps#"Zg  
{ tP&{ J^G  
for(int i=1;;i++) m=#aHF  
{ <.;@ksCPW{  
String header=con.getHeaderFieldKey(i); ~}epq6L>  
if(header!=null) 58qaA\iw  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); jM{qRfOrg  
Utility.log(header+" : "+con.getHeaderField(header)); B8`R(vu;  
else t)YFT
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break; yjeq
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} 8[vl3C  
} pHq{S;R2G  
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public void splitterStop() u?F7L8q]  
{ r!"CH5dT  
bStop = true; ,| $|kO/  
} ---Ks0\V  
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} %:yHMEG]'  
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/* |6\FI?  
**FileAccess.java okd ``vG  
*//文件访问(定位，写) g?k#wj1uH  
package NetFox; BaNU}@  
import java.io.*; yHa:?u6  
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public class FileAccessI implements Serializable{ RPa?Nv?e  
/6Jy'"+'0  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ~ wJ3AqNC?  
RandomAccessFile oSavedFile; p*(U*8Q  
long nPos; i-K"9z|)  
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//`cwnjp  
public FileAccessI() throws IOException < e7<t9  
{ e0G}$ as  
this("",0); /ej/&x15  
} ILu0J`;}  
{7
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public FileAccessI(String sName,long nPos) throws IOException JsWq._O{/  
{ ]ft~OqLg!  
oSavedFile = new RandomAccessFile(sName,"rw"); Bsih<`KF^  
this.nPos = nPos; 6x (L&>F  
oSavedFile.seek(nPos); ~t.WwxY+  
} ^R8U-V8:  

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public synchronized int write(byte[] b,int nStart,int nLen) uZ=UBir  
{ S,)|~#5x  
int n = -1; h.}t${1ZC  
try{ 8R??J>h5\  
oSavedFile.write(b,nStart,nLen); &ttv4BC^r  
n = nLen; ,;+91lR3  
} #$vhC u<I  
catch(IOException e) zv
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{ foP>w4pB  
e.printStackTrace (); 9qu24zz$P  
} 44fq1<.K  
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return n; 9,EaN{GM  
} w?$u!X  
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}
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/* fj t_9-.  
**SiteInfoBean.java QSs$   
*/ a+>W  
package NetFox; 4gkV]" H!  
!qw=I(  
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public class SiteInfoBean { 
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6nWx>R<  
private String sSiteURL; //Site's URL J"2ODB5"  
private String sFilePath; //Saved File's Path D"] [&m  
private String sFileName; //Saved File's Name noUZ9M|hz  
private int nSplitter; //Count of Splited Downloading File 72`/xryY  
_9-D3_P[3  
!{ESeBSCG  
public SiteInfoBean() 0-~6} r$  
{//nSplitter的缺省值为5 &pY G  
//default value of nSplitter is 5 QH' [(  
this("","","",5); `)C`_g3Ew  
} 4bFVyv  
wAOVH].  
~!d)J  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 1DlcO>#@  
{ ?^$4)Y>Kf  
sSiteURL= sURL; B?ob{K@  
sFilePath = sPath; G*~*2>~  
sFileName = sName; :6k DUFj}
 
this.nSplitter = nSpiltter; ?! _pP|  
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8~Hs3\Hp  
} Y7V&zF{  
L%O8vn^3  
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public String getSSiteURL() P~ pbx  
{ 4x{ti5Y0  
return sSiteURL; U8$dG)PhA  
} ^}7t:  
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public void setSSiteURL(String value) E,"btBg  
{ @bCiaBdi  
sSiteURL = value; 34^Cfh  
} JR<-'  
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:;WDPRx  
public String getSFilePath() wBHDof xX  
{ 0\ w[_H  
return sFilePath; yIf}b  
} yj+b/9My   
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public void setSFilePath(String value) ^
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{ 4"(zi5`e  
sFilePath = value; _";pk _  
} T<?BIQz(}  
({nSs5)$  
A y[L{!)2{  
public String getSFileName() ]]o[fqD-Zn  
{ }Y ];ccT  
return sFileName; . \0=1P:  
} xi. KD
 
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public void setSFileName(String value) ly%B!P|  
{
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sFileName = value; V>92/w.fe  
} R0<Vd"  
m e{SVG{  
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public int getNSplitter() .{Oq)^!ot  
{ Ka\b_P&  
return nSplitter; 0w. _}Cz  
} p=gUcO8  
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public void setNSplitter(int nCount) mJR T+SZ  
{ A'(F%0NF6  
nSplitter = nCount; bI(98V,t  
} MXV4bgltT  
} gjLgeyyWC  
nW'x#0-  
}*R6p?L5  
/* p;=(-4\V}  
**Utility.java }8#Czo jt  
*/ 0*x?  
package NetFox; ~"Ki2'j)^]  
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TJ:Lz]l >  
public class Utility { 0|;=mYa4M  
6J+ZeBk??  
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public Utility() %WN2 xCSf  
{ b.;}Hq>  
{2@96o2}  
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} Ngnjr7Q={T  
),,vu  
//线程睡眠 K_n%`
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public static void sleep(int nSecond) \]%U?`A  
{ Zh
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try{ <=M
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Thread.sleep(nSecond); K^\9R  
} M7 !" t  
catch(Exception e) a"0~_=  
{ E:
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e.printStackTrace (); e,8-P-h~T  
} 7!%"8Rl-  
} ]EQ/*ct  
O]lfs>>x  
//日志 o:<3n,T  
public static void log(String sMsg) ? Q}{&J  
{ T`sM4 VWqU  
System.err.println(sMsg); 'zK*?= ^jk  
} A4
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8t%1x|!  
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public static void log(int sMsg) 6! 'Xo:p  
{ t/|^Nt@XT  
System.err.println(sMsg); 9OUhV[D  
} plfB}p  
} 51x,[y+Xe  
kx[8#+P  
'oG'`ED"  
/* '! (`?  
**TestMethod.java v(`$%V.  
*/ 2+PIZ6=hN  
package NetFox; =xoTH3/,>  
7[LC*nrr  
dyd_dK/  
public class TestMethod { ?3#X5WT  
bxs@_fH  
zVu}7v()  
public TestMethod() |4vk@0L  
{ ///xx/weblogic60b2_win.exe Q"O _h  
try{ Dg`W{oj  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); [z\*Zg  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Vs >1%$If  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 6]VTn-  
fileFetch.start(); I8y\D,  
} 8CCA/6  
catch(Exception e){e.printStackTrace ();} lgl/| ^ Uw  
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2;/hF
wm  
} Eq t61O$x  
m`Z4#_s2  
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public static void main(String[] args) Xma0k3;-  
{ a^BD55d?  
new TestMethod(); 8g\.1<~  
} i>;G4  
} g(1'i1  
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