http断点续传简单实现（java)

/* XM+.Hel  
**SiteFileFetch.java P5B,= K>r  
*/ " wT?$E  
package NetFox; G"m0[|XH  
import java.io.*; ,J+L_S+B~  
import java.net.*; (y?F8]TfM  
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public class SiteFileFetch extends Thread { ;p~!('{P  
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SiteInfoBean siteInfoBean = null; //文件信息Bean t\QLj&h}E  
long[] nStartPos; //开始位置 z]hRc8g}d  
long[] nEndPos; //结束位置 <Qv/# k  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 h4KMhr  
long nFileLength; //文件长度 XRkUv>Yk  
boolean bFirst = true; //是否第一次取文件 gQSVPbzK  
boolean bStop = false; //停止标志 `Rq|*:LV  
File tmpFile; //文件下载的临时信息 QGOkB  
DataOutputStream output; //输出到文件的输出流 ~.G$0IJY  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） GTfM
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public SiteFileFetch(SiteInfoBean bean) throws IOException Hicd -'  
{ R!/JZ@au<  
siteInfoBean = bean; CeOA_M  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Va.TUz4  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); VFF5Tp  
if(tmpFile.exists ()) }&7kT7ogO  
{ Y~I>mc]  
bFirst = false; #l&*&R~>  
read_nPos(); t@#5 G* _Q  
} ??B!UXi4R  
else t>%b[(a  
{ 3}phg  
nStartPos = new long[bean.getNSplitter()]; OMmfTlM%  
nEndPos = new long[bean.getNSplitter()]; >*O5Ry:4  
} =,ax"C?pR  
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} WdS1v%  
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public void run() l}-k>fug  
{ UJp'v_hN  
//获得文件长度 WW3Jxd  
//分割文件 :+QNN<  
//实例FileSplitterFetch |
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//启动FileSplitterFetch线程 yp=sL' E  
//等待子线程返回 NRG~ya >  
try{ 9cN@y<_I  
if(bFirst) gU&+^e >  
{ =Oh$pZRymu  
nFileLength = getFileSize(); &Q"vXs6Gt  
if(nFileLength == -1) ljrJC  
{ Zp_j\B  
System.err.println("File Length is not known!"); ZW"f*vwQo  
} p}!)4EI=  
else if(nFileLength == -2) am.d^'  
{ _a"| :kX  
System.err.println("File is not access!"); CpX[8>&osD  
} Fq+Cr?-  
else "N&ix*($  
{ )q4n
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for(int i=0;i<nStartPos.length;i++) x%@M*4
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{ U{lf$  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); <x;g9Z>(  
} W2$rC5|  
for(int i=0;i<nEndPos.length-1;i++) xZ2 1iQeN  
{ buzpmRoN)  
nEndPos = nStartPos[i+1]; LR#.xFQ+  
} twldwuN  
nEndPos[nEndPos.length-1] = nFileLength; 9%ct   
} 75R4[C6T  
} ]!P6Z?  
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//启动子线程 MMaS  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; *Z
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for(int i=0;i<nStartPos.length;i++) uW[AnQ1w  
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), k"BM1-f  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), x?0(K=h,  
nStartPos,nEndPos,i); [.$%ti
*!  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); MGwXZ7?E  
fileSplitterFetch.start(); g_tEUaiK  
} 5$Kv%U  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ZZ!6O/M  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); #vy[v22  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", w\Q(wH'  
nEndPos = " + nFileLength); &];W#9"Z  
// fileSplitterFetch[nPos.length-1].start(); yl' IL#n]r  
E'8XXV^I?P  
<R2SV=]Sq#  
//等待子线程结束 TDPQ+Kg_  
//int count = 0; @{<^rLt  
//是否结束while循环 8BS Nm  
boolean breakWhile = false; D2MIV&pahP  
+\PLUOk  
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while(!bStop) 0_^3 |n  
{ 6+>X`k%D  
write_nPos(); M6]:^;p'  
Utility.sleep(500); I7f:
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breakWhile = true; >K%+h)%kI  
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for(int i=0;i<nStartPos.length;i++) vf?m6CMU!  
{ \)MzUOZn  
if(!fileSplitterFetch.bDownOver) mv*M2NuhT  
{ &;vMJ   
breakWhile = false; ]nxSVKE4p  
break; pnv)D}"  
} <1~_nt~(*  
} uAk>VPuuZ  
if(breakWhile) \Q?#^<O  
break; H}usL)0&&  
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FB~IO#E8W  
//count++; vBY?3p,0p  
//if(count>4) mI^S%HT  
// siteStop(); ^v3J ld  
} +-hfl/$  
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System.err.println("文件下载结束！"); shY8h   
} 3?&P^{  
catch(Exception e){e.printStackTrace ();} ronZa0  
} 2rf#Bq?7  
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//获得文件长度 gPpk0LZi  
public long getFileSize() fzjtaH?  
{ =AuxM
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int nFileLength = -1; /)Weg1b  
try{ )b|xzj@  
URL url = new URL(siteInfoBean.getSSiteURL()); urD{'FQf  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); !,DA`Yt  
httpConnection.setRequestProperty("User-Agent","NetFox"); /EVXkf0  
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int responseCode=httpConnection.getResponseCode(); 'L%)B-,n  
if(responseCode>=400) kxY9[#:<fB  
{ l
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processErrorCode(responseCode); xUB{{8B:L  
return -2; //-2 represent access is error 8/|1FI  
} :-+j,G9t  
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String sHeader; [5P1 pkZ  
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for(int i=1;;i++) C^ ~[b o  
{ n=h!V$X  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); uX&Tn1Kg  
//Utility.log(in.readLine()); Lyjp  
sHeader=httpConnection.getHeaderFieldKey(i); C7MCM
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if(sHeader!=null) *,XT;h$'>  
{ T FK#ign  
if(sHeader.equals("Content-Length")) 69``j{Z+  
{ ]ex2c{ G  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); DV~g  
break; 04!akPP<  
} ]Mgxv>zRbs  
}  11-?M  
else t,yMO  
break; S\A9r!
2  
} EvDg{M}  
} ,@@FAL  
catch(IOException e){e.printStackTrace ();} 1lHBg  
catch(Exception e){e.printStackTrace ();} X0]5I0YP  
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Utility.log(nFileLength); [mG:PTK3  
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return nFileLength; ,mD{4 >7  
} x^!LA,`j  

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//保存下载信息（文件指针位置） BGL-lJrG  
private void write_nPos() C,dRdEB>  
{ h1QrFPQnu  
try{ '<hgc  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ne'Y{n(8%  
output.writeInt(nStartPos.length); T|h'"3'  
for(int i=0;i<nStartPos.length;i++) NA
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{ .^!uazPE0  
// output.writeLong(nPos); -ob1_0  
output.writeLong(fileSplitterFetch.nStartPos); [7=?I.\Cr7  
output.writeLong(fileSplitterFetch.nEndPos); Hu7WU;w  
} sFonc  
output.close(); d?1[xv;  
} N/
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catch(IOException e){e.printStackTrace ();} 9':MD0P/M  
catch(Exception e){e.printStackTrace ();} jR mo9Bb2  
} Te&5IB-  
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{~~'

 
//读取保存的下载信息（文件指针位置） Q`(.Blgm;  
private void read_nPos() vI+X9C?  
{ d<afO?"  
try{ 2vX!j!_  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); j<_)Y(x>  
int nCount = input.readInt(); "|KD$CY  
nStartPos = new long[nCount]; 5s=L5]]r_j  
nEndPos = new long[nCount]; mpDQhD[n  
for(int i=0;i<nStartPos.length;i++) C;oT0(  
{ E|omC_h  
nStartPos = input.readLong(); qZDP-  
nEndPos = input.readLong(); e:zuP.R  
} s<fzk1LZ  
input.close(); Tq!.M1{&  
} J={IGA  
catch(IOException e){e.printStackTrace ();} hYU4%"X  
catch(Exception e){e.printStackTrace ();} {N 0i 3e s  
} s N|7  

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private void processErrorCode(int nErrorCode) WeRX~  
{ <&p0:S
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System.err.println("Error Code : " + nErrorCode); G}p*oz~  
} B>,&{ah/5J  
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//停止文件下载 Y SD
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public void siteStop()
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{ @6:J$B~)u  
bStop = true; 29AWg(9?aS  
for(int i=0;i<nStartPos.length;i++) +'QE-#%{=  
fileSplitterFetch.splitterStop(); =6LF_=}  
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} yUp"%_t0  
} <c$K3  
//负责部分文件的抓取 *Z C$DW!-  
**FileSplitterFetch.java Mg76v<mv<  
*/ !Au9C   
package NetFox; M~t;&po  
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import java.io.*; 76rRF   
import java.net.*; ~AbTbQ3  
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public class FileSplitterFetch extends Thread { |$aTJ9 Iq:  
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String sURL; //File URL FF7  
long nStartPos; //File Snippet Start Position !%s&GD8&l  
long nEndPos; //File Snippet End Position K\a=bA}DG  
int nThreadID; //Thread's ID Eggdj+  
boolean bDownOver = false; //Downing is over mhZ60RW  
boolean bStop = false; //Stop identical q=(.N>%  
FileAccessI fileAccessI = null; //File Access interface A,'JmF$d  
#Kd^t=k  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException HHU0Nku@ho  
{ 3A>Bnb  
this.sURL = sURL; Az"(I>VfD  
this.nStartPos = nStart; uw,p\:D&  
this.nEndPos = nEnd; }HC6m{vH(  
nThreadID = id; DsZBhjCB  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 FG[YH5  
} b ?-VZA:  
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public void run() 4C
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{ S_ Pa .  
while(nStartPos < nEndPos && !bStop) E=9xiS  
{ 8Q2qroT  
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try{ ]gHi5]\NC
 
URL url = new URL(sURL); q;<=MO/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); C%l+<wpXO  
httpConnection.setRequestProperty("User-Agent","NetFox"); CMI V"-  
String sProperty = "bytes="+nStartPos+"-"; 7eyVm;LQD  
httpConnection.setRequestProperty("RANGE",sProperty); |)pRkn8x  
Utility.log(sProperty); RZg8y+jM  
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InputStream input = httpConnection.getInputStream(); Gec?  
//logResponseHead(httpConnection); dvl'Sq<  
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byte[] b = new byte[1024]; RMfKM! vE  
int nRead; 'zg; *)x1/  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) D%+
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{ )*wM DM5q  
nStartPos += fileAccessI.write(b,0,nRead); F^/1 u  
//if(nThreadID == 1) 7i$)iNW  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); *49lM;  
} |pA  
(&)PlIi7  
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Utility.log("Thread " + nThreadID + " is over!"); UbnX%2TW  
bDownOver = true; Tt.#O~2:9  
//nPos = fileAccessI.write (b,0,nRead); ZVin+z  
} R;]z/|8  
catch(Exception e){e.printStackTrace ();} "nzQ$E>?$  
} y|7sh  
} ,@#))2<RK  
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@> ]O6P2  
//打印回应的头信息 N-9Vx#i  
public void logResponseHead(HttpURLConnection con) z3bRV{{YqN  
{ Us.")GiHE  
for(int i=1;;i++) y_7lSo8<  
{ :Q=
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String header=con.getHeaderFieldKey(i); s6k@WT?"^  
if(header!=null) t{ R\\j  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); I+VL~'VlS  
Utility.log(header+" : "+con.getHeaderField(header)); *:
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else /~O>He  
break; XjRk1~  
} ye-EJDZN  
} j+9;Cp]NV  
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public void splitterStop() zarxv| }$  
{ 5p}ri,Y<  
bStop = true; 2lc  
} <y}9Twdy  
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} <?>1eU%  
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/* x* 9 Xu"?  
**FileAccess.java (^@rr[.o7  
*//文件访问(定位，写) T)Zef  
package NetFox; Sf>#Zqj/  
import java.io.*; $1E'0M`  
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public class FileAccessI implements Serializable{ Hh1]\4D,4  
;(3!#4`q(]  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 iCtDV5  
RandomAccessFile oSavedFile; s0To^I  
long nPos; cp)BPg  
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public FileAccessI() throws IOException yp!7^
  
{ [2P6XoI#  
this("",0); hjgB[ &U>  
} ,6 IKkyD  
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public FileAccessI(String sName,long nPos) throws IOException YctWSfh  
{ W5Uw=!LdEY  
oSavedFile = new RandomAccessFile(sName,"rw"); 0g`$Dap  
this.nPos = nPos; UasU/Q <  
oSavedFile.seek(nPos); dJjkH6%}  
} Rz#q68  
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public synchronized int write(byte[] b,int nStart,int nLen) $3=S\jyfK  
{ ~JS B
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int n = -1; &<LBz|  
try{ <2SWfH1>  
oSavedFile.write(b,nStart,nLen); -.OZ  
n = nLen; +,1 Ea )  
} i*((@:  
catch(IOException e) ]Zz.n5c  
{ mIZ6[ ?  
e.printStackTrace (); )~0TGy|  
} ri%j*Kn  
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return n; \iP5.3C  
} rS!M0Hq>t  
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} P-/"sD  
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1,(WS F  
/* hv`I`[/J  
**SiteInfoBean.java v5F+@ug  
*/ dmWCNeja.  
package NetFox; y_'6bpb  
M@z_tR'3\  
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public class SiteInfoBean { .I?~R:(Ig  
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private String sSiteURL; //Site's URL xnfJruT  
private String sFilePath; //Saved File's Path #W&o]FAA3y  
private String sFileName; //Saved File's Name as(/ >p  
private int nSplitter; //Count of Splited Downloading File {;N2 &S o  
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public SiteInfoBean() '55G:r39  
{//nSplitter的缺省值为5 &f}w&k2yj  
//default value of nSplitter is 5 Bf.iRh0Q5  
this("","","",5); ez5J+  
} {a__/I>)  
Y1ks'=c>  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 9Z21|
5  
{ >C19Kie72  
sSiteURL= sURL; SK#&%Yk  
sFilePath = sPath; XF+4*),  
sFileName = sName; ;:&|DN3;  
this.nSplitter = nSpiltter; ZS%W/.?  
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} 1BEs> Sm  
J?dLI_{<  
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public String getSSiteURL() )o<^6Ic%7  
{ ''(rC38  
return sSiteURL; lWecxD$  
} "X^<g{]  
4&=</ok6`0  
*:Rs\QH   
public void setSSiteURL(String value) @({=~ W^  
{ 5|=J\Lp2I  
sSiteURL = value; @gfW*PNjlP  
} *FktI\tS  
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public String getSFilePath() P1Z"}Qw  
{ J8!2Tt  
return sFilePath; 1f<R,>  
} m$_b\^we  
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public void setSFilePath(String value) >x JzV  
{ '9Z`y_~)G  
sFilePath = value; `hZh}K^  
} *d3-[HwZCL  
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public String getSFileName() =`QYy-b X  
{ xy]O8>b  
return sFileName; (0H=f6N  
} 1,%`vlYv  
j(Lz& *4  
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public void setSFileName(String value) ?UAuUFueA  
{ XQ]vJQYIR  
sFileName = value; %*}rLn"?  
} &J
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88~Nrl=co  
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public int getNSplitter() ~c35Y9-5  
{ )0-A;X2  
return nSplitter; <7VLUk}  
} m2\\!C]f  
\ saV8U7B  
ud r\\5  
public void setNSplitter(int nCount) =^rt?F4  
{ 5[Vr {^)  
nSplitter = nCount; hm1s~@oEm  
} ~tA ^K  
} KsP2./N  
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P!W%KobZ7|  
/* ; R}>SS'  
**Utility.java TQT3]h6  
*/ =G:Krc8w@  
package NetFox; q*UHzE:LI  
s#s">hMrI  
<=">2WP{  
public class Utility { IQPu%n{0v  
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|@X^_L.!  
public Utility() }#FV{C]  
{ CW+kKN  
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y'
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} ]zol?  
,%TBW,>  
//线程睡眠 e,xL~P{|  
public static void sleep(int nSecond) )XDBK*!  
{ $pES>>P  
try{ .7.lr[
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Thread.sleep(nSecond); ,p d-hu  
} hI:.Qp`r  
catch(Exception e) r'OqG^6JFN  
{ =y][j+WH  
e.printStackTrace (); r@4A%ql<  
} Hh1_z
d|  
} [<#jK}g  
o pTXI*QA  
//日志 0F|t@?S  
public static void log(String sMsg) >9{?&#]x  
{ e'K~WNT  
System.err.println(sMsg);  g{Hgs  
} 1p}H,\o  
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Te-p0x?G.  
public static void log(int sMsg) 1B4Qj`:+0  
{ s* (a  
System.err.println(sMsg); ,.<mj !YE  
} XDY]LAV  
} z%D7x5!,R  
/pj[c;aO  
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/* f7x2"&?vg  
**TestMethod.java =LaEEL  
*/ I\Op/`_=E  
package NetFox; iJzB
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public class TestMethod { wo@ T@Ve~  
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public TestMethod() &en. m>9,  
{ ///xx/weblogic60b2_win.exe sy"}25s  
try{ |oPRP1F-;e  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); &&
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//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 3uuIISK  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 7X>I
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fileFetch.start(); bIU.C|h@  
} KqFI2@v   
catch(Exception e){e.printStackTrace ();} OH t)z.  
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} /J
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}-oba_  
public static void main(String[] args) *{ rorir  
{ YlrN^rO  
new TestMethod();  (Q8!5s  
} Q4u.v,sE  
} %,T*[d&i  
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