http断点续传简单实现（java)

/* 5;S.H#YOpO  
**SiteFileFetch.java z2c6T.1M  
*/ "3hMq1NQ`g  
package NetFox; 5IN(|B0  
import java.io.*; F?cK-.  
import java.net.*; }Lv;

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public class SiteFileFetch extends Thread { :4s1CC+@\  
_
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SiteInfoBean siteInfoBean = null; //文件信息Bean M;NX:mX9  
long[] nStartPos; //开始位置 6RM/GM  
long[] nEndPos; //结束位置 Ie^l~G
b  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 f5k6`7Vj]  
long nFileLength; //文件长度 =EIkD9u  
boolean bFirst = true; //是否第一次取文件 $N\Ja*g  
boolean bStop = false; //停止标志 F"<vaqT2  
File tmpFile; //文件下载的临时信息 zJXplvaL;  
DataOutputStream output; //输出到文件的输出流 z=FZiH  
l@\
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Tr|JYLwF
 
public SiteFileFetch(SiteInfoBean bean) throws IOException *kVV+H<X|b  
{ b\ PgVBf9  
siteInfoBean = bean; +3`alHUK  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); [V!tVDs&'o  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); dd["dBIZ '  
if(tmpFile.exists ()) 2Hdu:"j  
{ ]d`VT)~vje  
bFirst = false; fatf*}eln  
read_nPos(); >MK98(F  
} e%6QTg5#  
else &?vgP!d&M  
{ i&k7-<  
nStartPos = new long[bean.getNSplitter()]; 6Iw\c  
nEndPos = new long[bean.getNSplitter()];
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} ~4"dweu?  
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} 
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public void run() gJhiGYx  
{ 2[CdZ(k]5  
//获得文件长度 3~\[7I/  
//分割文件 <1%$Vq  
//实例FileSplitterFetch _~pbqa,  
//启动FileSplitterFetch线程 80;(Gt@<"  
//等待子线程返回 s<Fl p  
try{ vFsLY  
if(bFirst) @P"p+  
{ c(%|: P^  
nFileLength = getFileSize(); Ev P{p  
if(nFileLength == -1) D6^6}1WI  
{ z]Ue|%K  
System.err.println("File Length is not known!"); nOz.G"  
} ;$tSb ~K+  
else if(nFileLength == -2) BB'OCN  
{ 2m[<]$  
System.err.println("File is not access!"); HmwT~  
} $kKjgQS(  
else l+R+&b^  
{ [9 RR8  
for(int i=0;i<nStartPos.length;i++) ]q-Y }1di8  
{ /=, nGk>  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); k'"%.7$U!  
} %[yJ4WL  
for(int i=0;i<nEndPos.length-1;i++) rD>f|kA?L  
{ ((I%'  
nEndPos = nStartPos[i+1]; >U3cTEs cj  
} (~en (  
nEndPos[nEndPos.length-1] = nFileLength; |W\(kb+  
} m9A
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} FE{FGMq  
+U.I( 83F  
9I/N4sou  
//启动子线程 MxGW(p  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; p^u:&Quac  
for(int i=0;i<nStartPos.length;i++) 3{h_&Gbo'D  
{ pBPl6%C.X-  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), V/;B3t~f  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), PY0j9$i?  
nStartPos,nEndPos,i); )];K .zP  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); pU7lnS[  
fileSplitterFetch.start(); 0<B$#8  
} 27< Enq]  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), zkdetrR  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 4YX3+oS  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", t!\tF[9e  
nEndPos = " + nFileLength); K}
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// fileSplitterFetch[nPos.length-1].start(); -7(@1@1  
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//等待子线程结束 m<g~H4  
//int count = 0; @jlw_ob2g  
//是否结束while循环 B !=F2  
boolean breakWhile = false; C=4Qlt[`  
qWKAM@  
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while(!bStop) 7 ^mL_SMj  
{ ohGfp9H
 
write_nPos(); E1U",CMU  
Utility.sleep(500); oFGhNk  
breakWhile = true; :Qf '2.h)  
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for(int i=0;i<nStartPos.length;i++) LAe6`foW/  
{ 4vV:EF-  
if(!fileSplitterFetch.bDownOver) +|>k
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{ }k G9!sf  
breakWhile = false; we?76t:-  
break; N<KS(@v y  
} O|N{v"o  
} *~j@*{u  
if(breakWhile) q,U+qt  
break; f
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//count++; h@]XBv  
//if(count>4) Bv%GJ
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// siteStop(); l/ ;  
} "4,?uPi  
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System.err.println("文件下载结束！"); SrK<fAkx  
} ye? 'Ze  
catch(Exception e){e.printStackTrace ();} c>~*/%+  
} ,V:SN~P66+  
^J8lBLqe  
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//获得文件长度 >q1L2',pK  
public long getFileSize() -701j'q{  
{ GU8sO@S5#  
int nFileLength = -1; !V g`  
try{ 4J([6<  
URL url = new URL(siteInfoBean.getSSiteURL()); pDCeQ6?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); KX7>^Bt&k  
httpConnection.setRequestProperty("User-Agent","NetFox"); 6,9>g0y'NG  
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int responseCode=httpConnection.getResponseCode(); U,-39mr  
if(responseCode>=400) h"lv7;
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{ Ev(>z-{F  
processErrorCode(responseCode); @qlK6tE`  
return -2; //-2 represent access is error \3aoM{ztD  
} #!KE\OI;@5  
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String sHeader; )fSOi||C  
r|P
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for(int i=1;;i++) zEyN)  
{ 8j %Tf;  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Gc;{\VU  
//Utility.log(in.readLine()); 6N S201o  
sHeader=httpConnection.getHeaderFieldKey(i); O[)kboY  
if(sHeader!=null) 5m(^W[u `  
{ Q &K  
if(sHeader.equals("Content-Length")) rOOT8nkR#  
{ b4ONh%  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); A_5P/ARmI  
break; 0h\smqm  
} -Z Ugx$  
} ndz]cx  
else vucxt }Ti  
break; Om@C X<(9C  
} :GP]P^M;G@  
} ApV~(k)W  
catch(IOException e){e.printStackTrace ();} ~C`^6UQr/?  
catch(Exception e){e.printStackTrace ();} V<uR>TD(  
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Utility.log(nFileLength); \(Y\|zC'0$  
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return nFileLength; D(RTV
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} ^y1j.M@q  
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//保存下载信息（文件指针位置） .1Al<OLL  
private void write_nPos() [t@Mn  
{ wlk4*4dKn  
try{ L(-b@Joh  
output = new DataOutputStream(new FileOutputStream(tmpFile)); _JE"{ ;  
output.writeInt(nStartPos.length); b@f$nS B  
for(int i=0;i<nStartPos.length;i++) '*w00  
{ CtAwBQO  
// output.writeLong(nPos); [knN:{ l  
output.writeLong(fileSplitterFetch.nStartPos); r^paD2&}  
output.writeLong(fileSplitterFetch.nEndPos); ~%=MpQ3  
} 5r8<7g:>C  
output.close(); q~ZNd3O  
} 78# v  
catch(IOException e){e.printStackTrace ();} R$TB1w9]  
catch(Exception e){e.printStackTrace ();} QpA/SmJ  
} 71gT.E  
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@u]rWVy;\[  
//读取保存的下载信息（文件指针位置） \$e)*9)  
private void read_nPos() *b/`Ya4  
{ E5xzy/ZQ  
try{ 1Z
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ~r`9+b[9{  
int nCount = input.readInt(); iS Gq!D  
nStartPos = new long[nCount]; SB|Qa}62  
nEndPos = new long[nCount]; '~&X wZ&  
for(int i=0;i<nStartPos.length;i++) DSk/q-'u  
{ F,dx2ZPIs?  
nStartPos = input.readLong(); (Dl$kGn  
nEndPos = input.readLong(); W$OG(m!W>  
} s1NKLt  
input.close(); FUjl8b-|  
} W7\f1}]H  
catch(IOException e){e.printStackTrace ();} }w<7.I  
catch(Exception e){e.printStackTrace ();} S.m{eur!,E  
} CcFn.omA  
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private void processErrorCode(int nErrorCode) |>htvDL  
{ 6%Pdy$ P  
System.err.println("Error Code : " + nErrorCode); Vz~nT  
} OJ$]V,Z00x  
-[!P!d=  
*ikc]wQr$  
//停止文件下载 -~ Mb  
public void siteStop() 5Z\#0":e  
{ ws|;`  
bStop = true; .#Z%1U%P.  
for(int i=0;i<nStartPos.length;i++) #9xd[A: N  
fileSplitterFetch.splitterStop(); m{uxIza  
)3w@]5j  
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} g,95T Bc  
} aL%AQB,  
//负责部分文件的抓取 muZ~*kMc  
**FileSplitterFetch.java 9Hu/u=vB<  
*/ JS
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package NetFox; X+}1  
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import java.io.*;
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import java.net.*; I'iGt~4$  
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{
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public class FileSplitterFetch extends Thread { _D_LgH;}  
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String sURL; //File URL SNE#0L'}  
long nStartPos; //File Snippet Start Position V8-oYwOR  
long nEndPos; //File Snippet End Position
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int nThreadID; //Thread's ID z3M6V}s4  
boolean bDownOver = false; //Downing is over w1"nffhO  
boolean bStop = false; //Stop identical 8C~]
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FileAccessI fileAccessI = null; //File Access interface MP 2~;T}~  
l
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException \z7SkZt,GT  
{ rT5Ycm@  
this.sURL = sURL; 9Z'8!$LYg  
this.nStartPos = nStart; q51Uf_\/  
this.nEndPos = nEnd; p)
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nThreadID = id; @u%_1  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 EC8b=B<DE  
} .dQQoyR+O  
+H#U~p$  
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public void run() Ii_ojQP-z  
{ 88h3|'*  
while(nStartPos < nEndPos && !bStop) ),!;| bh  
{ F
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try{ .j>hI="b  
URL url = new URL(sURL); /&{$ pM|?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
)!:Lzi  
httpConnection.setRequestProperty("User-Agent","NetFox"); pV,P|>YTf  
String sProperty = "bytes="+nStartPos+"-"; (t
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httpConnection.setRequestProperty("RANGE",sProperty); _b.qkTWUB  
Utility.log(sProperty); P7MeX(Tay  
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InputStream input = httpConnection.getInputStream(); Y
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//logResponseHead(httpConnection); yK2^Y]Ku?  
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byte[] b = new byte[1024]; )V:]g\t  
int nRead;  n>`as  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) /'DsB%7g  
{ YH
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nStartPos += fileAccessI.write(b,0,nRead); -!L"'
)  
//if(nThreadID == 1) X'% ;B  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (S`2[.j
 
} jDN ]3Y`  
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Utility.log("Thread " + nThreadID + " is over!"); +_xOLiu  
bDownOver = true; YxinE`u~  
//nPos = fileAccessI.write (b,0,nRead); F]t(%{#W  
} pzgSg[|  
catch(Exception e){e.printStackTrace ();} }~h(w^t  
} -x4X O`b  
} B8%{}[q  
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j"@93D~  
//打印回应的头信息 *[R eb%  
public void logResponseHead(HttpURLConnection con) j>/ ,
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{ U Gpu\TB  
for(int i=1;;i++) x5WW--YR+  
{ ,SiY;(b=\  
String header=con.getHeaderFieldKey(i); U*P. :BvG  
if(header!=null) *(>}Y  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); dG71*)<)t  
Utility.log(header+" : "+con.getHeaderField(header)); }sFm9j7yR  
else Iu*^xn  
break; C2w2252T  
} 5W@jfh)  
} v[n7"  
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public void splitterStop() 'EfR|7m  
{ 4r0b)Y&I  
bStop = true; Yl$
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} i^!ez5z  
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} 6q6FB  
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s  
*d',Vuv&[  
/* d'Axum@  
**FileAccess.java G>+1*\c  
*//文件访问(定位，写) NAzX". g  
package NetFox; k') E/n  
import java.io.*; FG!X"<he  
fQ=MJ7l  
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public class FileAccessI implements Serializable{ y{a$y}7#X  
.+(
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ^+9sG$T_EV  
RandomAccessFile oSavedFile; `H3.,]
 
long nPos; `3'0I/d"z  
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public FileAccessI() throws IOException ;u(Du-Os!  
{ OLj\-w^  
this("",0); nPgeLG"00  
} W Qc>  

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public FileAccessI(String sName,long nPos) throws IOException P0-Fc@&Y  
{ x/:4{  
oSavedFile = new RandomAccessFile(sName,"rw"); :ECi+DxBK  
this.nPos = nPos; O!Z|r?  
oSavedFile.seek(nPos); WmQ01v  
} )*d W=r/$V  
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}Y17*zp%  
public synchronized int write(byte[] b,int nStart,int nLen) xyE1Gw`V  
{ L~^*u_U]  
int n = -1; M-uMZQe  
try{ lRP1&FH0  
oSavedFile.write(b,nStart,nLen); $8BE[u|H2  
n = nLen; U`x bPQ  
} Q\3 Z|%  
catch(IOException e) 1Fi86  
{ qJ_1*!!91  
e.printStackTrace (); Sm2>'C  
} 8Z2.`(3c[  
l**;k+hw  
RP`2)/sMT  
return n; \M/6m^zS  
} <[/%{sUNC  
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} ^5t  
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/* oAZh~~tp  
**SiteInfoBean.java te4= S  
*/ VRW]a  
package NetFox; AP\ofLmq  
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public class SiteInfoBean { !z zW2>  
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private String sSiteURL; //Site's URL s2
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private String sFilePath; //Saved File's Path yO>V/5`  
private String sFileName; //Saved File's Name 
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private int nSplitter; //Count of Splited Downloading File I}Xg&-L  
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public SiteInfoBean() *xM/;)  
{//nSplitter的缺省值为5  [&P`ak  
//default value of nSplitter is 5 Ld|V^9h1;  
this("","","",5); ~L+]n0*  
} ^Dx#7bsDZR  
|@o6NZ<9N  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) .]}N55M  
{ DjW$?>  
sSiteURL= sURL; W%!@QY;E(  
sFilePath = sPath; y0
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sFileName = sName; XvSIWs  
this.nSplitter = nSpiltter; }+Vv0jX|V  
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} []&(D_e"  
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public String getSSiteURL() hQ
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{ S9Yt1qb  
return sSiteURL; ZcryAm:I  
} $~'Tf>e  
?Cci:Lin  
O(OmGu4%  
public void setSSiteURL(String value) n!N\zx8  
{ (3EUy"z-  
sSiteURL = value; M'1HA  
} :nQp.N*p  
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"6I[4U"@  
public String getSFilePath() 
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{ '
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return sFilePath; a`Z{ xme=  
} Z-|li}lDr  
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public void setSFilePath(String value) ^@}#me@  
{ Eqphd!\#6  
sFilePath = value; GH3#E*t+[  
} Qp!Y.YnPd_  
*PM}"s  
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public String getSFileName() -WT3)On  
{ e!o(g&wBj  
return sFileName; cj(X
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} hswTn`f  
<FmBa4ONU  
XS0V:<+,  
public void setSFileName(String value) {~GR8 U  
{ O2H/rFx4  
sFileName = value; c)1=U_61  
} wR7aQg  
c d%h
W  
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public int getNSplitter() AQci,j"  
{ $ly0h W  
return nSplitter; }~*rx7p  
} lvufkVG|  
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public void setNSplitter(int nCount) ?*K<*wBw#  
{ ,ZK]i CGk  
nSplitter = nCount; b]`^KTYK  
} iUNnPJh  
} 5a$$95oL  
#O</\|aH)i  
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/* w<d*#$[,*  
**Utility.java &`PbO  
*/ 2xmT#m  
package NetFox; UpeQOC  
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public class Utility { /w~C~6z @!  
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@Qo,p  
public Utility() A1<k1[5fJ  
{ MYTS3(  
U,3d) ]Zy&  
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} 3LrsWAz'  
j_pw^I$C  
//线程睡眠 &HxT41pku  
public static void sleep(int nSecond) WLy7'3@  
{ B,0+HoP  
try{ )_O.{$ to  
Thread.sleep(nSecond); Y\u_+CG*  
} /.-m}0h|W-  
catch(Exception e) aL$j/SC  
{ B*Cb6'Q  
e.printStackTrace (); 4sd-zl$Of  
} U$$3'n  
} 8DT@h8tA  
?zE<  
//日志 4[H,3}p9H  
public static void log(String sMsg) Spc&X72I  
{ W]~ZkQ|P  
System.err.println(sMsg); 2;R/.xI6v  
} W^ClHQ"Iy  
`1_FQnm)  
*(VbPp_H_  
public static void log(int sMsg) ^8\Y`Z0%  
{ '5cZzC 2  
System.err.println(sMsg); feg`(R2  
} dp< auA  
} | /#'S&!U  
;q&Z9lm  
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/* w}b<D#0XC  
**TestMethod.java eu=|t&FKk  
*/ q"p#H8  
package NetFox; !pV<n  
1G_xP^
H!  
a}GAB@YI  
public class TestMethod { Vd[2u  
KPg[-d  
\ >(zunL  
public TestMethod() FP@A;/c  
{ ///xx/weblogic60b2_win.exe UR\ZN@O  
try{ Z#LUez;&t#  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); I`#EhH  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ^s.oZj q  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 4Q/r[x/&C  
fileFetch.start(); A<;0L . J  
} I &cX8Tw  
catch(Exception e){e.printStackTrace ();} V!}L<cN  
yx 7loy$[  
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} F94V5_[  
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public static void main(String[] args) 6e&g$R v  
{ Rgs3A)[`d/  
new TestMethod(); yvS^2+jW  
} &(WE]ziuO  
} uq]iMz>  
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