http断点续传简单实现（java)

/* !0*=z~  
**SiteFileFetch.java ^*%p]r  
*/ "`C|;\w  
package NetFox; WO^smCk  
import java.io.*; ./J.OU1  
import java.net.*; Y\sLwLLlG  
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public class SiteFileFetch extends Thread { k$k
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SiteInfoBean siteInfoBean = null; //文件信息Bean burEo
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long[] nStartPos; //开始位置 q
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long[] nEndPos; //结束位置 .'5yFBS  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 2~Gcoda  
long nFileLength; //文件长度 8X5;)h   
boolean bFirst = true; //是否第一次取文件 dGP*bMCT  
boolean bStop = false; //停止标志 L.l%EcW=,  
File tmpFile; //文件下载的临时信息 _BtppQIWv  
DataOutputStream output; //输出到文件的输出流 {5^'u^E  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） !+9H=u  
public SiteFileFetch(SiteInfoBean bean) throws IOException .I {X  
{ Ai(M06P:h  
siteInfoBean = bean; IP&En8W+  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); >OZ+k(saL  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); &Vvy`JE  
if(tmpFile.exists ()) m5{Y  
{ Nz*qz"T  
bFirst = false; L>xcgV7  
read_nPos(); [UR+G8X21m  
} 5}e-\:J>B  
else CH`4FR.-  
{ B~u{LvTE  
nStartPos = new long[bean.getNSplitter()]; %w/o#*j<;  
nEndPos = new long[bean.getNSplitter()]; NTs< ;ED  
} [)Xu60?Q  
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} 2s?j5 Sd  
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public void run() "&Q-'L!M'/  
{ Dn<2.!ZKQ  
//获得文件长度 ^dYFFKQ  
//分割文件
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//实例FileSplitterFetch QRgWzaI  
//启动FileSplitterFetch线程 C&zgt :q6}  
//等待子线程返回 z})H$]:$  
try{
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if(bFirst) `^wF]R  
{ j05ahquI  
nFileLength = getFileSize(); L.l"'=M  
if(nFileLength == -1) V<
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{ HR.S.(t[_  
System.err.println("File Length is not known!"); +qD4`aI 
 
} o PR^Z pt  
else if(nFileLength == -2) }I#;~|v~<  
{ <LzN/I aJ  
System.err.println("File is not access!"); B/i,QBPF]  
} Q(oWaG  
else [-s0'z  
{ RTHdL  
for(int i=0;i<nStartPos.length;i++) [^1;8Tbk  
{ kxThtjgv  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); K&D -1u  
} \P&'4y~PL  
for(int i=0;i<nEndPos.length-1;i++) EG7
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{ y 9/27yWB  
nEndPos = nStartPos[i+1]; $hg
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} "aB]?4  
nEndPos[nEndPos.length-1] = nFileLength; yr[iAi"  
} kx]f`b  
} EOVHTDkKf  
.6(Bf$E  
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//启动子线程 lOI(+74  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; PX\}lTJ  
for(int i=0;i<nStartPos.length;i++) e9k}n\t3  
{ ,yAvLY5P  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Ga N4In[d  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), rQj.W6w=  
nStartPos,nEndPos,i); lv&<kYWY  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); m#grtmyMrI  
fileSplitterFetch.start(); 31Zl"-<#-  
} +%UXI$v  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), VP0wa>50!  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); _S2QY7/  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", A~h.,<+"  
nEndPos = " + nFileLength); + 5sTGNG  
// fileSplitterFetch[nPos.length-1].start(); 8l+\Qyj  

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)I.[@#-  
//等待子线程结束 wEKm3mY;  
//int count = 0; qJ5Y}/r  
//是否结束while循环 z/6kxV89  
boolean breakWhile = false; 
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while(!bStop) &P[eA u  
{ AM'-(x|  
write_nPos(); -Ww'wH'2  
Utility.sleep(500); :Oa|&.0l?  
breakWhile = true; 'u_'y  
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for(int i=0;i<nStartPos.length;i++) JS!rZi  
{ -.ha\t0J  
if(!fileSplitterFetch.bDownOver) HQQc<7c",  
{ j9x}D;?n  
breakWhile = false; Maf!,/U4  
break; pYceMZ$  
} bYgrKz@uK  
} 'JKFEUzM  
if(breakWhile) #*}4=  
break; l4L&hY^  
w<-CKM3qe  
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//count++; i^Ep[3  
//if(count>4) v)o
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// siteStop(); wEQV"I  
} Co[  r
hs  
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System.err.println("文件下载结束！"); %I&Hx<Hj  
} 0)yvyQ5  
catch(Exception e){e.printStackTrace ();} nd'zO#"m?  
} Vyu0OiGcR  
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//获得文件长度 7evE;KL  
public long getFileSize() oPo<F5M]d%  
{ x)THeH@  
int nFileLength = -1; M=`F $  
try{ FUvZMA$  
URL url = new URL(siteInfoBean.getSSiteURL()); `fY~Lv{4d_  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); psgXJe$  
httpConnection.setRequestProperty("User-Agent","NetFox"); 6@ToPbj4  
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int responseCode=httpConnection.getResponseCode(); bn~=d@'  
if(responseCode>=400) 6_^u}me  
{ m`I6gnLj  
processErrorCode(responseCode); HGh`O\f8  
return -2; //-2 represent access is error |XLx6E2F  
} 2}b1PMpZG  
%
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-9.S?N'T>;  
String sHeader; tm#T8iF  
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for(int i=1;;i++) a^,6[  
{ m9wV#Ldu  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); mI@E>VCV[  
//Utility.log(in.readLine()); st+X~;PX*  
sHeader=httpConnection.getHeaderFieldKey(i); )$#ov-]  
if(sHeader!=null) ;jo,&C  
{ `:}GE@]  
if(sHeader.equals("Content-Length")) |A8xy#  
{ 4F??9o8}  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); )l\BZndf  
break; H}dsd=yO  
} do+HPnfDzU  
} tceQn ^|<  
else 5m=3{lBi  
break; YB*ZYpRVl  
} UF|v=|*{#  
} ~+q$TV  
catch(IOException e){e.printStackTrace ();} (C!u3ke2D  
catch(Exception e){e.printStackTrace ();} h<$Vry}  
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Utility.log(nFileLength); &t+03c8g!  
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return nFileLength; }ytc oIuLf  
} m!$"-nh9  
]9l=geZd%;  
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//保存下载信息（文件指针位置） 4 "@BbVYR  
private void write_nPos() .%M=dL>  
{ %)i?\(/  
try{ p*-o33Ve  
output = new DataOutputStream(new FileOutputStream(tmpFile)); T,TKt%  
output.writeInt(nStartPos.length); rk-}@vp  
for(int i=0;i<nStartPos.length;i++) DSM,dO'  
{ kK16+`\+  
// output.writeLong(nPos); >(<OhS(  
output.writeLong(fileSplitterFetch.nStartPos); B&0-~o3WP  
output.writeLong(fileSplitterFetch.nEndPos); =L 7scv%i  
} |GA4fFE=  
output.close(); gX{V>T(<  
} A%"mySW  
catch(IOException e){e.printStackTrace ();} 15)=>=1mR.  
catch(Exception e){e.printStackTrace ();} c_yf=  
} :05>~bn>pC  
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//读取保存的下载信息（文件指针位置） :eo2t>zF-<  
private void read_nPos() Om\?<aul  
{ 0N;Pb(%7UU  
try{ "e&S*8QhM  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); k =ru) _$2  
int nCount = input.readInt(); z%}^9  
nStartPos = new long[nCount]; (fUXJ$  
nEndPos = new long[nCount]; cZe,l1$  
for(int i=0;i<nStartPos.length;i++) S"!nM]2L  
{ #W @6@Mv  
nStartPos = input.readLong(); erdWGUfQOe  
nEndPos = input.readLong(); r\F`xtR(  
} x&8HBF'  
input.close(); S=U*is  
} jI_TN5  
catch(IOException e){e.printStackTrace ();} d?$FAy'o5  
catch(Exception e){e.printStackTrace ();} _Su? VxU  
} XTG*56IzL  
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private void processErrorCode(int nErrorCode) $-|`#|CBd  
{ VuN= JX  
System.err.println("Error Code : " + nErrorCode); yxf|Njo0  
} ^*C8BzcH  
exiCy1[+  
' &^:@V  
//停止文件下载 od"Oq?~/t  
public void siteStop() /VgA}[%y  
{ Sy6Y3 ~7  
bStop = true; l`:M/z6"  
for(int i=0;i<nStartPos.length;i++) "]f0wLzh  
fileSplitterFetch.splitterStop(); l5b? 'L  
.,)NDG4Q  
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} @{+c6.*}  
} s_N?Y)lS+(  
//负责部分文件的抓取 6wYd)MDLL  
**FileSplitterFetch.java lM3UjR|@  
*/ n-be8p)-  
package NetFox; *r6+Vz  
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import java.io.*; \S{ise/U  
import java.net.*; C_rlbl;T  
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public class FileSplitterFetch extends Thread { wN-3@  
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String sURL; //File URL 02g}}{be8  
long nStartPos; //File Snippet Start Position 4nmc(CHQ:  
long nEndPos; //File Snippet End Position g""1f%U_p  
int nThreadID; //Thread's ID g)u ~GA*=  
boolean bDownOver = false; //Downing is over iq)4/3"6  
boolean bStop = false; //Stop identical
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FileAccessI fileAccessI = null; //File Access interface 6J9^:gXW~  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Kr3L~4>  
{
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this.sURL = sURL; 8 ;y N  
this.nStartPos = nStart; +Em+W#i%?  
this.nEndPos = nEnd; vn}:$|r$J  
nThreadID = id; l`G .lM(  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Zg"g/I.+d  
} R=yn4>I  
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public void run() GD<xmuo  
{ &k*sxW'  
while(nStartPos < nEndPos && !bStop) wWB-P6  
{ yANk(  
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try{ ^ 
ry   
URL url = new URL(sURL);  w~wpm7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); n@<+D`[.V  
httpConnection.setRequestProperty("User-Agent","NetFox"); FO#`}? R`  
String sProperty = "bytes="+nStartPos+"-"; I&^B
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httpConnection.setRequestProperty("RANGE",sProperty); uO8z.  
Utility.log(sProperty); DUUQz:?{J  
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InputStream input = httpConnection.getInputStream(); bq#*XCt#  
//logResponseHead(httpConnection); r)UtS4 7  
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byte[] b = new byte[1024]; atRWKsY<  
int nRead; 2{:bv~*I0F  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Hg(%gT  
{ s4uZ;  
nStartPos += fileAccessI.write(b,0,nRead); `1aEV#;  
//if(nThreadID == 1) @2ZE8O#I  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); lcR53X  
} = s^KZV  
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Utility.log("Thread " + nThreadID + " is over!"); Loo48  
bDownOver = true; c `C /U7j  
//nPos = fileAccessI.write (b,0,nRead); >|Ps23J#  
} BM9J/24  
catch(Exception e){e.printStackTrace ();} <RH2G  
} /qp)n">  
} nA$zp  
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//打印回应的头信息 L6S!?t.{Yv  
public void logResponseHead(HttpURLConnection con) vDl6TKXcu  
{ `R]B<gp  
for(int i=1;;i++) QS.t_5<U  
{ "l0z?u  
String header=con.getHeaderFieldKey(i); j_i/h
"  
if(header!=null) faH113nc  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); K'z|a{ru.{  
Utility.log(header+" : "+con.getHeaderField(header));  d(!W  
else SKO*x^"eU  
break; ,?s3%<\2   
} Tv2d?y  
} CJ0
{>?  
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^PHWUb+``  
public void splitterStop() 92zo+bc  
{ \0. c_  
bStop = true; IjJO;  
} lQ/u#c$n  
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} cZ>h[XX[  
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/* 2 VgFP3  
**FileAccess.java T#&tf
^;  
*//文件访问(定位，写) =^  
package NetFox; [wKnJu  
import java.io.*; J~dk4D\  
-n.ltgW@   
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public class FileAccessI implements Serializable{ }\+7*|  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 B[2 qI7D$  
RandomAccessFile oSavedFile; xz9xt  
long nPos; JQSp2b@'H  
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public FileAccessI() throws IOException ZcT%H*Ib]9  
{ OB-gH3:  
this("",0); ShFC@)<lJ  
} ?;{d  
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public FileAccessI(String sName,long nPos) throws IOException CJ'pZ]\G  
{ G.#`DaP  
oSavedFile = new RandomAccessFile(sName,"rw"); x+1Cs$E;  
this.nPos = nPos; 7r,s+u.  
oSavedFile.seek(nPos); 2h Wtpus  
} h?cf)L  
fU?P__zU4  
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public synchronized int write(byte[] b,int nStart,int nLen) }ZPO^4H;-  
{ HfQZRDH  
int n = -1; 99xs5!4s  
try{ 2QUZBrs s  
oSavedFile.write(b,nStart,nLen); ui_nvD:  
n = nLen; Q7<_>)e^  
} 5X8GR5P  
catch(IOException e) 2>bTcud>  
{ oRJ!J-Z]  
e.printStackTrace (); |s<IZ2z]}R  
} soSdlV{  
/iz{NulOz*  
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return n; &nJH23h^  
} B;k3YOg  
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} CJn{tP  
M|HW$8V3_2  
=IbDGw(  
/* `>.^/SGu>?  
**SiteInfoBean.java j=&]=0F  
*/ BYhF?  
package NetFox; ao+lLCr  
!&8nwOG  
0[/GEY@  
public class SiteInfoBean { R&lJ& SgC  
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private String sSiteURL; //Site's URL H>zX8qP+  
private String sFilePath; //Saved File's Path n\X'2  
private String sFileName; //Saved File's Name >h!>Ll  
private int nSplitter; //Count of Splited Downloading File nU^-D1s{  
[;/4'  
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public SiteInfoBean() O %x<  
{//nSplitter的缺省值为5 !z EW)  
//default value of nSplitter is 5 9FGe(t<  
this("","","",5); *wvd[q h  
} O~wZU Zf  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) $oPx2sb  
{ %3Ba9Nmid  
sSiteURL= sURL; [9hslk  
sFilePath = sPath; g?TPRr~$9  
sFileName = sName; t>~a/K"  
this.nSplitter = nSpiltter; ][gr(-68  
,b b/ $   
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} IdHydY1  
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public String getSSiteURL() _m?TEqB  
{ `f|Gw5R  
return sSiteURL; j=q*b Qr  
} >EacXPt-O  
/-{C,+cB  
FV 0x/)<z  
public void setSSiteURL(String value) \/wbk`2  
{ sxP1.= W  
sSiteURL = value; vO?\u`vY  
} }|KNw*h$  
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public String getSFilePath() yA+NRWWj  
{ 88]4GVi  
return sFilePath; NZ|(#` X  
} bXiOf#:''  
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public void setSFilePath(String value) qcmf*Yl:v  
{ [. rULQ
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sFilePath = value; iNlY\67sW  
} 2#i*'.  
# $N)  
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public String getSFileName() @P'("qb~  
{ -;1nv:7Z3  
return sFileName; l KdY!j"  
} yPn!1=-(  
6T`F'Fk[  
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public void setSFileName(String value) s7789pR  
{ *XCgl*% *  
sFileName = value; 5#WyI#YNG  
} {:%A  
#Wf9`  
j%q,]HCANh  
public int getNSplitter() u)hr  
{ f[XsnN2  
return nSplitter; eI^Q!b8n  
} aioN)V  
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public void setNSplitter(int nCount) cns~)j~  
{ 5McOSy  
nSplitter = nCount; U65a_dakk  
} *"HA=-Z;  
} > &VY  
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/* \F;  S  
**Utility.java 5bZjW~d  
*/ &tjv.t  
package NetFox; 4b
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public class Utility { @p\te7(P%  
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+
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public Utility() "J=A(w5   
{ -Uo"!o>x|  
^5{0mn_4i  
.1q4Q\B<  
} .Bs~FIe^  
e.n*IJ_fz  
//线程睡眠 hgU#2`fS  
public static void sleep(int nSecond) !xRboPg  
{ U#mrbW  
try{ 2@jlF!zC  
Thread.sleep(nSecond); M&h`uO/[  
} DxvD 1u  
catch(Exception e) <uf,@N5m  
{ hLo>jE  
e.printStackTrace (); +8zCol?j  
} nuucYm%IF-  
} !]l!I9  
0{k*SCN#  
//日志 4f-I,)qCBk  
public static void log(String sMsg) OBp&64  
{ }~bx==SF6!  
System.err.println(sMsg); '7ps_pz  
} 9C"d7--  
';J><z{>  
{sR|W:fS$  
public static void log(int sMsg) 79y'PFSms  
{ b'mp$lt!  
System.err.println(sMsg); [CAV"u)0  
} sI% =G3o=  
} ?>}&,:U}  
MVYf-'\^
  
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/* h;RKF\U:"  
**TestMethod.java E!6Nf[  
*/ M!Wjfq ^~  
package NetFox; ?c0@A*:o  
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,b!]gsds  
public class TestMethod { F
8En)#  
rd0[(-  
t)n}S;iD  
public TestMethod() [Fo"MeH?R  
{ ///xx/weblogic60b2_win.exe 5a^b{=#Y  
try{ --'!5)U  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); bKb}VP  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); =e!o  
SiteFileFetch fileFetch = new SiteFileFetch(bean); o8h1  
fileFetch.start(); /q\{OsrX  
} a]%>7yr4  
catch(Exception e){e.printStackTrace ();} enw7?|(  
3w!,@=
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} C0#"U f  
X ^\kI1  
lr-:o@q{  
public static void main(String[] args) /2jw]ekQ'  
{ Y?b4* me  
new TestMethod(); @`S8d%6P  
} snccDuS  
} dZi?Z  
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