http断点续传简单实现（java)

/* y{qKb:~wv  
**SiteFileFetch.java BG@[m  
*/ g>Kh?(  
package NetFox; htqC~B{1E  
import java.io.*; ZP7wS
  
import java.net.*; `l}r&z(8  
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public class SiteFileFetch extends Thread { ^F$iD (f  
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SiteInfoBean siteInfoBean = null; //文件信息Bean >:U{o!N`#_  
long[] nStartPos; //开始位置 Nxt z1  
long[] nEndPos; //结束位置 W#[3a4%m  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Fm.IRu<\`  
long nFileLength; //文件长度 Z|Xv_Xo|4  
boolean bFirst = true; //是否第一次取文件 xXc3#n  
boolean bStop = false; //停止标志 ,HO@bCK  
File tmpFile; //文件下载的临时信息 vn=0
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DataOutputStream output; //输出到文件的输出流 <3aW3i/jTc  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） a{8g9a4  
public SiteFileFetch(SiteInfoBean bean) throws IOException 8U&93$  
{ `wLa.Gzj  
siteInfoBean = bean; 0Z~G:$O/i  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); y <21~g=  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); EY 9N{  
if(tmpFile.exists ()) sr,8Qd0M  
{ h7W<$\P  
bFirst = false; B6a   
read_nPos(); 8:(e~? f6  
} 2JRX ;s~  
else * d[sja+  
{ RjCEo4b-.H  
nStartPos = new long[bean.getNSplitter()]; 79
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nEndPos = new long[bean.getNSplitter()]; f<~S0[H  
} }>u<,
 
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} mq~L1<f  
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public void run() ;;l-E>X0  
{ |yow(2(F@  
//获得文件长度 <swYo<?J#  
//分割文件 [
6t!}q  
//实例FileSplitterFetch |#!P!p}  
//启动FileSplitterFetch线程 ? v2JuhRe  
//等待子线程返回 !NFP=m1  
try{ r6eApKZ>f6  
if(bFirst) 0?nm`9v6  
{ ,=kQJ|  
nFileLength = getFileSize(); |F#L{=B  
if(nFileLength == -1) t{)J#8:g  
{ CK+_T}+-  
System.err.println("File Length is not known!"); m`lsUN,  
} Z}'"c9oB  
else if(nFileLength == -2) )Dq/fW  
{ :.M"M$MRp8  
System.err.println("File is not access!"); KUqD<Jj?  
} HNtl>H  
else FsYsQ_,R3  
{ ,d3
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for(int i=0;i<nStartPos.length;i++) (
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{ [m3k_;[  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 6+[7UH~pm^  
} f}>S"fFI  
for(int i=0;i<nEndPos.length-1;i++) hd}"%
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{ ~?)ST?&  
nEndPos = nStartPos[i+1]; mT2Fn8yC1  
} 
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nEndPos[nEndPos.length-1] = nFileLength; %A<|@OSdOa  
} "Q~-C|x  
} z2lEHa?w  
7Q9zEd"d  
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//启动子线程 LMvsYc~]q  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; yXx}'=&!0  
for(int i=0;i<nStartPos.length;i++) 7BhRt8FSD+  
{ h[
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), oLXQ#{([  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Vi~F Q  
nStartPos,nEndPos,i); Y"&c .  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); c*g(R.!  
fileSplitterFetch.start(); ]+B#SIC;  
} :8~*NSEFd  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3[L)q2;}$N  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); "K8<X  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", E}$K&<J'-  
nEndPos = " + nFileLength); -l!;PV S|  
// fileSplitterFetch[nPos.length-1].start(); QDC]g.x  
kE
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@:s|X  
//等待子线程结束 X>#!s Lt  
//int count = 0; QxmVImn"  
//是否结束while循环 5!PU+9Kh  
boolean breakWhile = false; m{bw(+r  
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{]}}rx'|P  
while(!bStop) ega
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{ :hp=>^$Y  
write_nPos(); sGCV um}  
Utility.sleep(500); WlnI`!)d  
breakWhile = true; U9KnW]O%"  
,&sBa{0  
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for(int i=0;i<nStartPos.length;i++) N(]>(S o  
{ .TURS  
if(!fileSplitterFetch.bDownOver) ;TK:D=p4  
{ ,zLi{a6  
breakWhile = false; /EOtK|E  
break; @Kd lX>i  
} m3k}Q3&6Z  
} v|XEC[F  
if(breakWhile) hNV"{V3`{  
break; GJA3  
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^AUmIyf_  
//count++; }cll? 2  
//if(count>4) PF1m :Iz`d  
// siteStop(); zX!zG<<K  
} 3H%oTgWk  
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System.err.println("文件下载结束！"); mb*L'y2r  
} ]y,6  
catch(Exception e){e.printStackTrace ();} Mp~E$f  
} 1@H3!V4  
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:CN,I!:  
//获得文件长度 AG#5_0]P~  
public long getFileSize() '(kySf[  
{ )ll`F7B-  
int nFileLength = -1; h{]l?6`  
try{ ti'a^(  
URL url = new URL(siteInfoBean.getSSiteURL()); "YGs<)S  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); /0 ,#c2aq  
httpConnection.setRequestProperty("User-Agent","NetFox"); bf `4GD(  
_?3bBBy  
+>oVc\$  
int responseCode=httpConnection.getResponseCode(); }Y5Sf"~M  
if(responseCode>=400) gUCv#:  
{ 
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processErrorCode(responseCode); Gt[!q\^?  
return -2; //-2 represent access is error p3*}!ez4  
} gJ>?<F;  
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String sHeader; Z8Fbx+~"  
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for(int i=1;;i++) itM6S$  
{ nVoPTr  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ());  _tN"<9v.  
//Utility.log(in.readLine()); _.Y?BAQ  
sHeader=httpConnection.getHeaderFieldKey(i); Xb42R1  
if(sHeader!=null) A1p;Ye
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{ s} ,p>8  
if(sHeader.equals("Content-Length")) :?{ **&=  
{ Nl7"|()e  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Fk>
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break; b:>(U.   
} rZZueYuXO  
} u(?  
else J;+iW*E:  
break; L '342(  
} &|H?J,>  
} '1=t{Rw
 
catch(IOException e){e.printStackTrace ();} MZE8Cvq0  
catch(Exception e){e.printStackTrace ();} 7 #_{UJ%  
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Utility.log(nFileLength); ;*+jCL2F  
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return nFileLength; j%b/1@I  
} OGrVy=rd  
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//保存下载信息（文件指针位置） 2<yE3:VX  
private void write_nPos() y&A*/J4P  
{ .8l\;/o|  
try{ ]xA;*b;|h  
output = new DataOutputStream(new FileOutputStream(tmpFile)); uU6+cDp  
output.writeInt(nStartPos.length); iU{F\>  
for(int i=0;i<nStartPos.length;i++) c0u!V+V%  
{ dV8mI,h  
// output.writeLong(nPos); !tF
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output.writeLong(fileSplitterFetch.nStartPos); m"~$JA u  
output.writeLong(fileSplitterFetch.nEndPos); [z`U9J  
} N>7INK  
output.close(); `RfhxzI  
} cgm]{[
f  
catch(IOException e){e.printStackTrace ();} ^!1mChf  
catch(Exception e){e.printStackTrace ();} 9rtcI[&?0  
} $ W(m  
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)`^t,x<S  
//读取保存的下载信息（文件指针位置） d$kGYMT"  
private void read_nPos() y_38;8ex  
{ YQiTx)_  
try{ VLc=!W}  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); d> `9!)  
int nCount = input.readInt(); (H<S&5[  
nStartPos = new long[nCount]; sn/^#Aa=N  
nEndPos = new long[nCount]; G1vWHa7n;f  
for(int i=0;i<nStartPos.length;i++) *\I?gDON  
{ myFjw@  
nStartPos = input.readLong(); 7Cx%G/(  
nEndPos = input.readLong(); wnP#.[,V  
} <Jo_f&&{  
input.close(); c{6!}0Q4  
} MMD4b}p  
catch(IOException e){e.printStackTrace ();} 3.?PdK&C  
catch(Exception e){e.printStackTrace ();} Ej ip%m  
} ;_,=  
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%.BbPR7?h  
private void processErrorCode(int nErrorCode) 6YQ&+4  
{ sE-E\+  
System.err.println("Error Code : " + nErrorCode); GNqw]@'Yf  
} ~9
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//停止文件下载 ITRv^IlF  
public void siteStop() uY,&lX+!  
{ *n N;!*J  
bStop = true; oJUVW"X6  
for(int i=0;i<nStartPos.length;i++) ,+KZn}>  
fileSplitterFetch.splitterStop(); s$:F^sxb  
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} VieC+Kk  
} C6ZM#}I$l  
//负责部分文件的抓取 T#Qn\8  
**FileSplitterFetch.java #]oVVf_  
*/ .:*V CDOM  
package NetFox; =E8lpN'  
pN&5vu30  
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import java.io.*; N't*eCi  
import java.net.*; C+cSy'VIK!  
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public class FileSplitterFetch extends Thread { DT8|2"H  
KO<Yc`Fs  
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String sURL; //File URL *{P"u(K  
long nStartPos; //File Snippet Start Position ,o]"G[J
k  
long nEndPos; //File Snippet End Position 0iinr:=u  
int nThreadID; //Thread's ID !uii|"  
boolean bDownOver = false; //Downing is over X5cl'J(j9  
boolean bStop = false; //Stop identical bBc<yaN  
FileAccessI fileAccessI = null; //File Access interface >lU[ lf+/  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException #{1w#Iz;  
{ @mW: FVI  
this.sURL = sURL; 3 ~0Z.!O  
this.nStartPos = nStart; a=&a)FR  
this.nEndPos = nEnd; z[B*sbS  
nThreadID = id; GN /]^{D  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 YBN@{P$  
} p)N=  
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public void run() S "R]i  
{ p[VBeO^%  
while(nStartPos < nEndPos && !bStop) 6n]fr9f  
{ v9(->X'  
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try{ 6&S;Nrg9  
URL url = new URL(sURL); E'?yI'~=  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); I#zrz3WU  
httpConnection.setRequestProperty("User-Agent","NetFox"); %kS+n_*  
String sProperty = "bytes="+nStartPos+"-"; IExo#\0'6  
httpConnection.setRequestProperty("RANGE",sProperty); m:59f9WXA  
Utility.log(sProperty); t>.mB@se|  
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InputStream input = httpConnection.getInputStream(); YgNt>4K  
//logResponseHead(httpConnection); ^]3Y11sI  
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byte[] b = new byte[1024]; %<CahzYc6  
int nRead; W
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) _(&^M[O  
{ XMd-r8yYr  
nStartPos += fileAccessI.write(b,0,nRead); N W :_)1  
//if(nThreadID == 1) vcy}ZqWBO  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); NDEltG(  
} .$y}}/{j?[  
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Utility.log("Thread " + nThreadID + " is over!"); !Low%rP  
bDownOver = true; r5h}o)J  
//nPos = fileAccessI.write (b,0,nRead); Q0i.gEwe  
} iY1%"x  
catch(Exception e){e.printStackTrace ();} @cA`del  
}  d!5C$C/x  
} x+x6F  
+!6aB|-  
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//打印回应的头信息 $@"o BCc  
public void logResponseHead(HttpURLConnection con) 3zo]*6p0  
{ Gkv<)}G  
for(int i=1;;i++) oMawINDa  
{ %Sr/'7 K  
String header=con.getHeaderFieldKey(i); f^z~{|%l!  
if(header!=null) wWv")dk3i  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 3e~ab#/  
Utility.log(header+" : "+con.getHeaderField(header)); "Kx2k>ym  
else U~n>k<`sr  
break; Veo:G{  
} D::$YR ~R  
} RO+B/)~0<  
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public void splitterStop() D7H,49#1Q  
{ &4Q(>"iL4  
bStop = true; 1OJD!juL$  
} ifTMoC%  
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} +e?mKLw14  
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/* SIv8EMGo  
**FileAccess.java /4J2F9:f  
*//文件访问(定位，写) >Ig%|4Hw  
package NetFox; eL3HX _2(  
import java.io.*; x
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public class FileAccessI implements Serializable{ GxE"q-G  
J0CEZ  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ~WXT0-,  
RandomAccessFile oSavedFile; FjF:Eh  
long nPos; #va|&QBZxM  
35I y\  
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public FileAccessI() throws IOException /nEt%YYh;x  
{ mL/]an@Y  
this("",0); 7hwl[knyB  
} =<mpZ'9gW  
 lc9aDt  
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public FileAccessI(String sName,long nPos) throws IOException /z:pid,_0  
{ SFCKD/8  
oSavedFile = new RandomAccessFile(sName,"rw"); to{/@^ D  
this.nPos = nPos; eQ_dO]Q  
oSavedFile.seek(nPos); sf
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} eAKK uML  
R|aA6} /I  
y57]q#k  
public synchronized int write(byte[] b,int nStart,int nLen) H }w"4s  
{ ReE-I/n8f  
int n = -1; zK`fX  
try{ 5N "fD{v{  
oSavedFile.write(b,nStart,nLen); XOgl>
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n = nLen; V^fSrW]  
} 7KIOI,qb6  
catch(IOException e) L".Qf|b*  
{ td!WgL,m  
e.printStackTrace (); ,,1H#;j  
} )D\cm7WX^[  

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return n; <Y~?G:v6+  
} 4a3Xz,[(a  
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} E*VUP5E  
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AZ' "M{wiI  
/* tYV%izE  
**SiteInfoBean.java /MFy%=0l  
*/ YI05?J}  
package NetFox; ~Wy&xs ZH  
f>.A^?  
U:6 J~  
public class SiteInfoBean { [U+6Tj,  
vzD3_ ?D  
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private String sSiteURL; //Site's URL 3C'`c=  
private String sFilePath; //Saved File's Path /3|uU  
private String sFileName; //Saved File's Name wq&|V  
private int nSplitter; //Count of Splited Downloading File ;%"YA  

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public SiteInfoBean() _22;hnG<iy  
{//nSplitter的缺省值为5 me]O  
//default value of nSplitter is 5 Z-(#}(HD  
this("","","",5);
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} H|8vW  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) C =fs[  
{ 6<0-GD}M  
sSiteURL= sURL; +g36,!q  
sFilePath = sPath; 'Okitq+O  
sFileName = sName; ! K? o H  
this.nSplitter = nSpiltter; 9>~UqP9  
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} I)$`@.  
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public String getSSiteURL() BLxtS  
{ gQy{OU  
return sSiteURL; x`N_tWZ  
} jR~2mf!h*e  
S"?py=7  
}'HJVB_  
public void setSSiteURL(String value) 0l#{7^e  
{ U9:?d>7  
sSiteURL = value; "0Xa?z8"  
} @91Q=S  
#6g-{OBv  
:`BZ,j_  
public String getSFilePath() 7{=<_  
{ :ie7HF  
return sFilePath; TTjj.fq6  
} 9( ;lcOz  
a<+Qw'  
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public void setSFilePath(String value) ]'Y vI!r  
{ 0gNwC~IA8  
sFilePath = value; I}oxwc  
} [\N,ow,n  
b 62 o  
51.! S  
public String getSFileName() rAqg<fR*  
{ (1e;7sNG@  
return sFileName; S-[]z*  
} F5Ce:+h  
=\s(v-8  
*yAC8\v  
public void setSFileName(String value) rg U$&O  
{ <d$kGCz  
sFileName = value; 
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} >@^z?nb  
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public int getNSplitter() ]/;0  
{ <qH>[
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return nSplitter; CL/8p;
  
} _%Q\G,a;  
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public void setNSplitter(int nCount) E"k\eZns&  
{ C:/ca)  
nSplitter = nCount; U(5(0r  
} >O[# 661  
} Zcd!y9]#  
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pE>~F  
/* U+sAEN_e k  
**Utility.java T1m097  
*/ !Dp4uE:Pq  
package NetFox; YIs(Q
 
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public class Utility { k^gnOU;  
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>  
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public Utility() 2!/*I:  
{ SZJ~ktXC-V  
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} @=x=dL
(  
Q%4>okj,  
//线程睡眠 ) ^PY-~o[  
public static void sleep(int nSecond) N3E Qq~lX  
{ MO)N0{.b  
try{ o?uTL>Zin  
Thread.sleep(nSecond); :pQZ)bF  
} !]qwRB$5  
catch(Exception e) CD1}.h  
{ Ty\&ARjb 8  
e.printStackTrace (); Nb\4Mv`  
} b8)>:F  
} }S'+Ytea  
s9) @$3\  
//日志 WQ4:='(  
public static void log(String sMsg) SFKW"cP  
{ Z[KXDQn8  
System.err.println(sMsg); B&|F9Z6D  
} s5FyP"V  
)ARfI)<1b  
l i}4d+  
public static void log(int sMsg) 7QL>f5Q
 
{ <jU[&~p  
System.err.println(sMsg); ch,<4E/c[R  
} c:"*MM RC  
} k!O#6
Z  
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t6_6Bl:  
/* ?m#X";^V  
**TestMethod.java uy{mSx?td  
*/ +#O?a`f  
package NetFox; 69(
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tDFN *#(  
2Xk(3J!!'a  
public class TestMethod { F>&Q5Kl R  
Oa\!5Pw1  
Ac<V!v71  
public TestMethod() ]hTYh^'e  
{ ///xx/weblogic60b2_win.exe 20;M
-Wx  
try{ qJB9z0a<Ov  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); "v4;m\g&:  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ,6PV"E)_  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ?sDm~]Z  
fileFetch.start(); yd5r]6ej  
} 2?rg&og6  
catch(Exception e){e.printStackTrace ();} 3toY#!1Ch  
g;w4:k)U  
^#e:q  
} VcIsAK".4[  
:6PWU$z$7  
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public static void main(String[] args)  f]q3E[?/  
{ *ghkw9/  
new TestMethod(); s@ m A\  
} j,eeQ KH  
} !TP8LQ  
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