http断点续传简单实现（java)

/* OJ1MV7&  
**SiteFileFetch.java ;0
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*/ /,yRn31[  
package NetFox; Zet80|q  
import java.io.*; vd[?73:C  
import java.net.*; Y<t(
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public class SiteFileFetch extends Thread { -uNM_|MO  
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SiteInfoBean siteInfoBean = null; //文件信息Bean "?G?G'yK>  
long[] nStartPos; //开始位置 2xBYJoF(  
long[] nEndPos; //结束位置 U;=1v:~d  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 O|nLIfT  
long nFileLength; //文件长度 )!lx'>0>  
boolean bFirst = true; //是否第一次取文件 pupt__NZ)n  
boolean bStop = false; //停止标志 pE {yVs  
File tmpFile; //文件下载的临时信息 k#n%at.g  
DataOutputStream output; //输出到文件的输出流 p
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） gh-i|i,  
public SiteFileFetch(SiteInfoBean bean) throws IOException Ltk-1zhI  
{ hs*n?vxp3  
siteInfoBean = bean; 
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); } 4ZWAzH  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); qi['~((  
if(tmpFile.exists ()) &a+=@Z)kf  
{ B"rO  
bFirst = false; C^fn[plL  
read_nPos(); d[YG&.}+8j  
} P @~)9W  
else $>zqCi2tB<  
{ AqT}^f
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nStartPos = new long[bean.getNSplitter()]; Khh}flRy  
nEndPos = new long[bean.getNSplitter()]; KJv[z  
} F+]cFx,/  
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} /bF>cpM  
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public void run() -6xh  
{ 8 q>  
//获得文件长度 m7u" awM^  
//分割文件 yUN>mD-  
//实例FileSplitterFetch *#1
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//启动FileSplitterFetch线程 nE56A
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//等待子线程返回 AYAbq}'Yt  
try{ "H]R\xp  
if(bFirst) mRy0zN>?  
{ D,()e^o  
nFileLength = getFileSize(); rYM@e  
if(nFileLength == -1) dwouw*8  
{ VHG}'r9KC%  
System.err.println("File Length is not known!"); :m<#\!?  
} 30O7u3Zrb  
else if(nFileLength == -2) T@Z-;
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{ xkQT#K=i  
System.err.println("File is not access!"); ~sdM~9@ '  
} i
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else Q)=2%X  
{ x2f=o|]D'  
for(int i=0;i<nStartPos.length;i++) ,'n`]@0?\  
{ >2ha6A[  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 2|&SG3e+(I  
} ZcN#jnb0/  
for(int i=0;i<nEndPos.length-1;i++) 2$'bOo
 
{ {$V2L4  
nEndPos = nStartPos[i+1]; R+El/ya:6  
}

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nEndPos[nEndPos.length-1] = nFileLength; y[zjs^-vCv  
} qCB{dp/  
} XRTiC#6  
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//启动子线程 K'y|_XsBB)  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; @aP1[(m
 
for(int i=0;i<nStartPos.length;i++) W![~"7?  
{ \}!
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), aMGyV"6(-6  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), F\jawoO9  
nStartPos,nEndPos,i); ,20l` :  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); L4ZB0PmN'  
fileSplitterFetch.start(); G_M8? G0  
} P-DW@drxF  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Tv9\`F[  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); !Sl_qL  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", }D-jTZlC  
nEndPos = " + nFileLength); '.jYu7   
// fileSplitterFetch[nPos.length-1].start(); dK4w$~j{k  
lqmr`\@)  
Ir=G\/A  
//等待子线程结束 +.gj/uy*  
//int count = 0; DG}s`'  
//是否结束while循环 VB`% u=  
boolean breakWhile = false; fYW9Zbov-  
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while(!bStop) ^9><qKb
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{ |7Qe{  
write_nPos(); \Yn0|j
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Utility.sleep(500); !L<z(dV|(  
breakWhile = true; Xpt9$=d  
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for(int i=0;i<nStartPos.length;i++) /(?s\}O  
{ clk]JA (  
if(!fileSplitterFetch.bDownOver) n}- _fx  
{ uL~wMX  
breakWhile = false; =MvB9gx@r  
break; "xnULQK  
} Xkk 8#Y
":  
} E^0a; |B[  
if(breakWhile) =\mJ5v"hA  
break; TM|PwY  
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//count++; [7NO !^  
//if(count>4) :98:U~d1  
// siteStop(); 6Kw?  
} +N'&6z0Wf  
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System.err.println("文件下载结束！"); 3d,:,f|h  
} #hk5z;J5
 
catch(Exception e){e.printStackTrace ();} Q3Y(K\  
} dkqyn"^  
c?KIHZ0  
#<s"?Y%-  
//获得文件长度 @}Q!K*  
public long getFileSize() UFC^lv  
{ X\>/'fC$  
int nFileLength = -1; qz.l  
try{ U$S{j&?  
URL url = new URL(siteInfoBean.getSSiteURL()); }0f~hL24  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); KUpj.[5qo  
httpConnection.setRequestProperty("User-Agent","NetFox"); g9=_^^Tg  
\}X[0ct2!  
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int responseCode=httpConnection.getResponseCode(); g)!q4 -q  
if(responseCode>=400) 2dK:VC4U  
{ a8gOb6qF/H  
processErrorCode(responseCode); ;/kmV~KG  
return -2; //-2 represent access is error H}q$6WE  
} )3<>H!yG}  
!Rgj'{  
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String sHeader; OJhMM-  
3_.%NgES|  
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for(int i=1;;i++) r8!pk~R5]  
{ KXpbee  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); o,S(;6pDJ  
//Utility.log(in.readLine()); %$'fq*8b  
sHeader=httpConnection.getHeaderFieldKey(i); 0F.S[!I  
if(sHeader!=null) <@lj\,  
{ 6L)7Q0Z  
if(sHeader.equals("Content-Length")) H/.UDz  
{ k8l7.e*  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); -F 9xPw  
break; h0HK~S#xBv  
} ~|N,{GaL  
} `U|zNizO  
else 0cVxP)J+  
break; mIPDF1=)  
} $RunGaX!=N  
} K
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catch(IOException e){e.printStackTrace ();} \ H#"  
catch(Exception e){e.printStackTrace ();} a5/Dz&>j6
 
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Utility.log(nFileLength); .g?D3$|K  
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return nFileLength; bUds E1f  
} ] W$
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* dk(<g=fM  
JIHIKH-#  
//保存下载信息（文件指针位置） Bk^o$3#  
private void write_nPos() F S$8F  
{ ZHlHnUo  
try{ ~B?Wg!  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 2$`Y 4b3t  
output.writeInt(nStartPos.length); zL3zvOhu}  
for(int i=0;i<nStartPos.length;i++) SoHaGQox  
{ k*!iUz{]  
// output.writeLong(nPos); +@H{H2J4  
output.writeLong(fileSplitterFetch.nStartPos); M{jq6c  
output.writeLong(fileSplitterFetch.nEndPos); `%EcQ}Nr  
} *-uzsq.W  
output.close(); wh2E$b(-  
} @,-D P41g  
catch(IOException e){e.printStackTrace ();} O{Mn\M6  
catch(Exception e){e.printStackTrace ();} :z *jl'L  
} x9S9%JG :  
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//读取保存的下载信息（文件指针位置） JfK4|{@  
private void read_nPos() SU6Aq?`@  
{ ^HtB!Xc  
try{ Pl-9FLJ  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); "WO0rh`  
int nCount = input.readInt(); ?STO#<a  
nStartPos = new long[nCount]; MZB}O" r  
nEndPos = new long[nCount]; {`T^&bk  
for(int i=0;i<nStartPos.length;i++) ,nGQVb   
{ TtKKU4yp  
nStartPos = input.readLong(); ez)Ks`  
nEndPos = input.readLong(); RCxwiZaf33  
} E H%hL5(  
input.close(); td23Z1Elk#  
} [1ClZ~f  
catch(IOException e){e.printStackTrace ();} m{~L Fhhd1  
catch(Exception e){e.printStackTrace ();} m~fDDQs  
} pn){v  
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private void processErrorCode(int nErrorCode) .+<Ka0  
{ eH[i<Z  
System.err.println("Error Code : " + nErrorCode); x5Fo?E  
} zA:q/i  
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A wk1d  
//停止文件下载 ;sqxFF@  
public void siteStop() zK{}   
{ 6Z2|j~  
bStop = true; 9_e_Ne`i`?  
for(int i=0;i<nStartPos.length;i++) 3(vm'r&5n>  
fileSplitterFetch.splitterStop(); ='_3qn.  
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} x;-D}#  
} }UQ,B  
//负责部分文件的抓取 @LDs$"f9=  
**FileSplitterFetch.java " vc4QH$  
*/ qDhZC*"9#D  
package NetFox; X8?@Y@  
a/3'!}&e  
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import java.io.*; %+;l|Z{Uf  
import java.net.*; 5,V*aP  
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public class FileSplitterFetch extends Thread { 2Vu?Y
 
9 `q(_\x  
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String sURL; //File URL m_BpY9c]5  
long nStartPos; //File Snippet Start Position 7Kb&BF|Q  
long nEndPos; //File Snippet End Position C8)Paop$  
int nThreadID; //Thread's ID Aayd3Ph0%  
boolean bDownOver = false; //Downing is over 1$6 u  
boolean bStop = false; //Stop identical MpvGF7H  
FileAccessI fileAccessI = null; //File Access interface _@gg,2 u-  
}9#GJ:x`  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException m}zXy\  
{ a?PH`5O  
this.sURL = sURL; +>Gw)|oX  
this.nStartPos = nStart; aGsO~ODc  
this.nEndPos = nEnd; s{V&vRr  
nThreadID = id; 8Q{9AoQ3'  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 &0:Gj3`  
} U5@B7v
1  
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public void run() ~ b66 ;  
{ qLc&.O.=  
while(nStartPos < nEndPos && !bStop) ;C , g6{  
{ FeQo,a

  
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try{ d(R8^v/L  
URL url = new URL(sURL); -vk/z+-^!  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ,# .12Q!  
httpConnection.setRequestProperty("User-Agent","NetFox"); JP {`
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String sProperty = "bytes="+nStartPos+"-"; jUR* |  
httpConnection.setRequestProperty("RANGE",sProperty); $ndBT+i  
Utility.log(sProperty); ]Y76~!N  
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InputStream input = httpConnection.getInputStream(); (nuTfmt>  
//logResponseHead(httpConnection); SMRCG"3qwA  
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byte[] b = new byte[1024]; "{H{-`Ni  
int nRead; 4gdXO  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ~|ZAS]  
{ 4e; le&  
nStartPos += fileAccessI.write(b,0,nRead); _%B,^0;C  
//if(nThreadID == 1) 3DB= Xh  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); )hoVB  
} W_Y56@7e  
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Utility.log("Thread " + nThreadID + " is over!"); >uQjygjj  
bDownOver = true;
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//nPos = fileAccessI.write (b,0,nRead); {)!ua7GF0H  
} 9L4;#cy  
catch(Exception e){e.printStackTrace ();} {.o4U0+  
} A=e1uBGA  
} GkU$Z @  
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eWD!/yr|  
//打印回应的头信息 /l3Oi@\  
public void logResponseHead(HttpURLConnection con) Gi$\th,  
{ e7&RZ+s#wZ  
for(int i=1;;i++) H$Pf$D$  
{ -~4kh]7%  
String header=con.getHeaderFieldKey(i); 2e3AmR@*  
if(header!=null) -ik((qx_  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); <@+L^Ps~z  
Utility.log(header+" : "+con.getHeaderField(header)); /7,@q?v  
else `_ZbA#R,  
break; 48G^$T{  
} BC1smSlJ  
} ;4/ n~  
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public void splitterStop() %]tW2s"  
{ 'xaEG,P  
bStop = true; YZnFU( j  
} -y?ve od#  
)-}<}< oO  
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} 6Rq +=X  
e},:QL0X  
EqI
s&){  
/*  :fy,%su  
**FileAccess.java _z.CV<  
*//文件访问(定位，写) s*i,Ph  
package NetFox; Lk^bzW>f  
import java.io.*; Tkp"mT v?<  
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public class FileAccessI implements Serializable{ }v_|N"@  
8(S|=cR  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Ep')@7^n  
RandomAccessFile oSavedFile; $`t2SD  
long nPos; +#(GU9_i+M  
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public FileAccessI() throws IOException rfSEL 57'  
{ 29|nt1Z  
this("",0); L/vw7XNrX  
} a8k`Wog  
{cdrMP@""  
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public FileAccessI(String sName,long nPos) throws IOException
p_apVm\t_  
{ O]F(vHK\   
oSavedFile = new RandomAccessFile(sName,"rw"); +x4*T  
this.nPos = nPos; 4ISIg\:c*  
oSavedFile.seek(nPos); pXh`o20I  
} I!K-* AB  
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/!/Pk'p=/  
public synchronized int write(byte[] b,int nStart,int nLen)
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{ 6ZjY-)h  
int n = -1; I,& g
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try{ Jiru~
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oSavedFile.write(b,nStart,nLen); @KZW*-"  
n = nLen; b0se-#+  
} 
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catch(IOException e) %6M%PR~
u  
{ la$%%@0/  
e.printStackTrace (); Bw[IW[(~!  
} c5i7mx:.  
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return n; +9<:z
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} X"HVK+  
/>>KCmc  
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} tBsvi%F  
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g^i\7'  
/* M$6;&T  
**SiteInfoBean.java B LZ<"npn  
*/ >29c[O"
[  
package NetFox; F^}d>2W(  
L}g#h+GP[  
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public class SiteInfoBean { uX1{K%^<TW  
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2:yXeSeA  
private String sSiteURL; //Site's URL X1V~.kvt)  
private String sFilePath; //Saved File's Path hOdU%  
private String sFileName; //Saved File's Name 2G3Hi;q18  
private int nSplitter; //Count of Splited Downloading File ^R7X!tOq4  
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public SiteInfoBean() ,t'"3<^Jg  
{//nSplitter的缺省值为5 6_tl_O7  
//default value of nSplitter is 5 F2)KAIl  
this("","","",5); cVmF'g  
} >+:cTQ|q  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) -Wre4^,v  
{ 7.kH="@  
sSiteURL= sURL; $8[JL\  
sFilePath = sPath; t[G7&ovj  
sFileName = sName; 9p4SxMMO  
this.nSplitter = nSpiltter; :)+)L@By  
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} Uqly|FS &n  
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!rG-[7K  
public String getSSiteURL() 6eNBldP!  
{ bp}]'NA  
return sSiteURL; Ngm/5Lc  
} 8'v:26   
n# FkgXP$  
._.Qf<7  
public void setSSiteURL(String value) lhBAT%U\  
{ D>-Pv-f/  
sSiteURL = value; #wh[F"zX  
} h]VC<BD6S  
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public String getSFilePath() 1gLET.I:  
{ p DU+(A4>  
return sFilePath; VArMFP)cz  
} )"E1/$*k  
%GMCyT  
C MGDg}  
public void setSFilePath(String value) ;H?tcb*  
{ VZ9`Kbu  
sFilePath = value; V
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} b,(<74!#8  
v~YGef;D  
.9<euPrz  
public String getSFileName() dzV2;  
{ @%^h|g8>Fu  
return sFileName; W&&C[@Jd3  
} 1{qG?1<zZ6  
UyDq`@h  
}5B\:*yW  
public void setSFileName(String value) koj*3@\p/  
{ 
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sFileName = value; T[J8zLO  
} "VMb1Zhf  
b.)jJLWv@  
:n?rk/F  
public int getNSplitter() b~TTz`HZ  
{ A[:(#iR5-E  
return nSplitter; fvA167\  
} pE.TG4  
5<7sVd.  
@ xTVX'$  
public void setNSplitter(int nCount) wV4MP1c$  
{ Nfmr5MU_  
nSplitter = nCount; TEC#owz  
} }rWg']  
} DMKtTt[}  
t^~itlE{  
?rdWhF]  
/* g}*p(Tp9:  
**Utility.java )k4&S{=  
*/ ~!/agLwY  
package NetFox; ?H8dyQ5"  
d"lk"R  
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public class Utility { *nV"X0&  
OM@z5UP  
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public Utility() nM99AW  
{ ]qEg5:yY  
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?07}\N0~  
} ._&SS,I5VZ  
++=jh6  
//线程睡眠 Rq|]KAN  
public static void sleep(int nSecond) y%<CkgZS  
{ NA#,q 8  
try{ CH5>u  
Thread.sleep(nSecond); d?/>Qqw:#  
} SPtx_+ Q)S  
catch(Exception e) K4OiKYq  
{ TW1#'G_#  
e.printStackTrace (); X*hPE=2` p  
} s Dsq:z  
} "@Qg]#]JH  
!=6\70lJ  
//日志 v:NQrN  
public static void log(String sMsg) g)IW9q2  
{ UM^~a$t  
System.err.println(sMsg); 8<=sU
O  
} [Y^h)k{-$  
}gd'pgN"t  
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public static void log(int sMsg)
*lQa^F  
{ va0}?fy.O%  
System.err.println(sMsg); 
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} wv Mp~  
} +HG
*T[%/  
P4 #j;k4P  
KD--w(4  
/* 2_)gJ_kP  
**TestMethod.java @H}Hjg_>m  
*/ ?^`fPH=  
package NetFox; dKa2_|k'  
*0<)PJ T  
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public class TestMethod { #IU^(W  
6S0Gjekr  
A!R'/m'VG  
public TestMethod() (,cG+3r]  
{ ///xx/weblogic60b2_win.exe f5/s+H!  
try{ as[! 9tB]
 
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ;{v2s;  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5);  #J  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 'UC1!
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fileFetch.start(); %pf9Yd0t  
} Af`Tr6)  
catch(Exception e){e.printStackTrace ();} gq="&  
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fm q(!  
} NB-%
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public static void main(String[] args) `O0y8  
{ d;{k,rP6  
new TestMethod(); O9AFQ)u   
} Ep3I*bQ Y  
} be?Bf^O>  
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