http断点续传简单实现（java)

/* +\c5]`  
**SiteFileFetch.java DJXmGt]  
*/ +ocol6G7W  
package NetFox; fF$<7O)+]  
import java.io.*; L
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import java.net.*; RXpw!  
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public class SiteFileFetch extends Thread { tqvN0vY5  

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SiteInfoBean siteInfoBean = null; //文件信息Bean u~
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long[] nStartPos; //开始位置 Pw7]r<Q  
long[] nEndPos; //结束位置 .9on@S  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 J!v3i*j\  
long nFileLength; //文件长度 iwZPpl";  
boolean bFirst = true; //是否第一次取文件 F3v!AvA|  
boolean bStop = false; //停止标志 x=hiQ>BIO0  
File tmpFile; //文件下载的临时信息 Qcq`libK  
DataOutputStream output; //输出到文件的输出流 nJG U-Z  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） &
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public SiteFileFetch(SiteInfoBean bean) throws IOException <;eW=HT+uq  
{ MSQEO4ge  
siteInfoBean = bean; g:'xae/]S  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); nA-.mWD_C  
if(tmpFile.exists ()) ]YnD  
{ \=?a/  
bFirst = false; fNli  
read_nPos(); Xtq_y'I  
} 7 S#J>*  
else UqFO|r"M  
{ E:sf{B'&  
nStartPos = new long[bean.getNSplitter()]; <ktrPlNuM  
nEndPos = new long[bean.getNSplitter()]; 53;}Nt#R  
} xjuN
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} $<dH?%!7  
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public void run() {3>$[bT  
{ Ga-k  
//获得文件长度 ~drS} V  
//分割文件
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//实例FileSplitterFetch jH5 k  
//启动FileSplitterFetch线程 l[mWf  
//等待子线程返回 Gv!2f  
try{ 6"LcJ%o  
if(bFirst) U2tV4_ e  
{ 'NXN& {  
nFileLength = getFileSize(); ?/
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if(nFileLength == -1) )0.kv2o.  
{ }>pknc?  
System.err.println("File Length is not known!"); 8O5s`qKMYT  
} 7{e 4c  
else if(nFileLength == -2) fIx+ILs  
{ P%V'4pc  
System.err.println("File is not access!"); fa jGZyd0:  
} |B?m,U$A!  
else rKe2/4>0X  
{ fy>{QC\  
for(int i=0;i<nStartPos.length;i++)
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{ v+W&9>  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); )al]*[lY  
} %~O,zs.2p  
for(int i=0;i<nEndPos.length-1;i++) e
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{ .KB^3pOpx  
nEndPos = nStartPos[i+1]; 2@n{yYwy  
} [`#CXq'  
nEndPos[nEndPos.length-1] = nFileLength; lK?uXr7^  
} pz!Zs."f)
 
} 2RVN\?s:  
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0#7>o^2  
//启动子线程 0cv{  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; g+8OekzB5  
for(int i=0;i<nStartPos.length;i++) du $:jN\}  
{ "(3[+W{|  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Q,,e+exbb5  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),
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nStartPos,nEndPos,i); bQzZy5,  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); j2t7'bO_  
fileSplitterFetch.start(); e@L=LW>  
}
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), x77*c._3v  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); !{+,B5 Hc  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", t>
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nEndPos = " + nFileLength); sNbxI|B  
// fileSplitterFetch[nPos.length-1].start(); JinU
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//等待子线程结束 fF!Yp iI"  
//int count = 0; h/QXPdV  
//是否结束while循环 qJf
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boolean breakWhile = false; +C^nO=[E  
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while(!bStop) {X!r8i  
{ vz@A;t  
write_nPos(); 3<e=g)F  
Utility.sleep(500); gT6z9  
breakWhile = true; &pxg. 3  
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for(int i=0;i<nStartPos.length;i++) <.%4 ! }f8  
{ Ij7p'a  
if(!fileSplitterFetch.bDownOver) rP'me2 B  
{ =ke2;}X  
breakWhile = false; =1@u  
break; PF0_8,@U  
} 'NbHa!  
} #z'  
if(breakWhile) M:=J^0  
break; T )&A2q  
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//count++; }g@v`5  
//if(count>4) dUD[e,?  
// siteStop(); WSPI|#Xr%  
}
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System.err.println("文件下载结束！"); bS{bkE>  
} "6("9"  
catch(Exception e){e.printStackTrace ();} ;_XFo&@  
} nd`1m[7MNu  
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//获得文件长度 av(6wht8  
public long getFileSize() 3RUy,s  
{ fQ7V/x!  
int nFileLength = -1; 7kC^ 30@T3  
try{ +Z,;,5'5G  
URL url = new URL(siteInfoBean.getSSiteURL()); H
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #QZe,"C9`  
httpConnection.setRequestProperty("User-Agent","NetFox"); 5frX  
9v#CE!  
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int responseCode=httpConnection.getResponseCode(); 5G}?fSQ>  
if(responseCode>=400) Q1lyj7c#x  
{ l&[O  
processErrorCode(responseCode); ),_@WW;k  
return -2; //-2 represent access is error uIY#e<)}G  
} xn

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String sHeader; g9OY<w5s]  
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g/4
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for(int i=1;;i++) (xycJ`N  
{ \-E^lIVF  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ??5Q)Erm1  
//Utility.log(in.readLine()); pG_;$8Hc  
sHeader=httpConnection.getHeaderFieldKey(i); k``_EiV4t  
if(sHeader!=null) yER(6V'\iQ  
{ y4yhF8E>;U  
if(sHeader.equals("Content-Length")) ^"E^zHM(  
{ UB@Rs|)  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader));
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break; 7K12 G!)  
} SV4E0c>  
} `Uq#W+r,  
else vN}#Kc\  
break; O}gV`q;  
} #x@$lc=k3  
} eNh39er  
catch(IOException e){e.printStackTrace ();} 7Y lchmd  
catch(Exception e){e.printStackTrace ();} W
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Utility.log(nFileLength); ZT*ydln  
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return nFileLength; #Bze
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} UhF-K#Z9  
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//保存下载信息（文件指针位置） hXw]K"  
private void write_nPos() AhN4mc@  
{ _1X!EH"  
try{ B
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output = new DataOutputStream(new FileOutputStream(tmpFile)); ?JbilK}a  
output.writeInt(nStartPos.length); NCXRevE  
for(int i=0;i<nStartPos.length;i++) P.se'z)E  
{ rE7G{WII  
// output.writeLong(nPos); PxX4[ P  
output.writeLong(fileSplitterFetch.nStartPos); LG0;#3YwH  
output.writeLong(fileSplitterFetch.nEndPos); h#I>M`|  
} $V
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output.close(); .D~;u-%|F  
} fy1|$d{'  
catch(IOException e){e.printStackTrace ();} Mc lkEfn  
catch(Exception e){e.printStackTrace ();} W_293["lS  
} S)(.,x  
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- nm"of\o  
//读取保存的下载信息（文件指针位置） F~ty!(c  
private void read_nPos() 4(n-_BS  
{ eSn+B;  
try{ 1y&\5kB  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); @3i\%R)n;  
int nCount = input.readInt(); J6"9v;V  
nStartPos = new long[nCount]; -]Bq|qTH[(  
nEndPos = new long[nCount]; >tS'Q`R
 
for(int i=0;i<nStartPos.length;i++) =HK!(C  
{ J`Q>3]wL  
nStartPos = input.readLong(); $GV7o{"&  
nEndPos = input.readLong(); 3m[vXr?  
} 63iUi9P  
input.close(); ^
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} Y>z>11yEB0  
catch(IOException e){e.printStackTrace ();} DPY}?dC  
catch(Exception e){e.printStackTrace ();} YRk(u7:0  
} D
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private void processErrorCode(int nErrorCode) >~rTqtKd  
{ O^PKn_OJ  
System.err.println("Error Code : " + nErrorCode); ?
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} 3d8L6GJ  
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//停止文件下载 =[ 46`-_  
public void siteStop() m,28u3@r  
{ cU (D{~  
bStop = true; _RYxD"my  
for(int i=0;i<nStartPos.length;i++) ;LfXi 8)  
fileSplitterFetch.splitterStop(); T.F!+  

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} 3yme1Mb  
} yF:1( 4  
//负责部分文件的抓取 8,Z_{R#|  
**FileSplitterFetch.java Tb}4wLu  
*/ Rh2+=N<X  
package NetFox; OKZV{Gja  
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import java.io.*; @u+]aI!`-  
import java.net.*; eeg)N1\  
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public class FileSplitterFetch extends Thread { 2szPAuN+  
lBE=(A`  
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String sURL; //File URL eIF5ZPSZi  
long nStartPos; //File Snippet Start Position "!P3R1;%  
long nEndPos; //File Snippet End Position %`r$g[<G  
int nThreadID; //Thread's ID b6M[q_  
boolean bDownOver = false; //Downing is over tFn)aa~L  
boolean bStop = false; //Stop identical unzr0x {  
FileAccessI fileAccessI = null; //File Access interface `7Q<'oK  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException tT8%yG}  
{ 2|y"!JqE1  
this.sURL = sURL; +/7?HGf  
this.nStartPos = nStart; SR hiQ  
this.nEndPos = nEnd; yzn%<H~  
nThreadID = id; @7c?xQVd$  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 TqQB@-!  
} /HE
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public void run() wu6;.xTLl  
{ 8rGgF]F  
while(nStartPos < nEndPos && !bStop) e]aDP1n3t  
{ wm@@$  
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try{ ",t?8465y  
URL url = new URL(sURL); **0~K";\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); h4}84}5d  
httpConnection.setRequestProperty("User-Agent","NetFox"); X`/k)N>l  
String sProperty = "bytes="+nStartPos+"-"; 3*bU6$|5FP  
httpConnection.setRequestProperty("RANGE",sProperty); qZh/IW  
Utility.log(sProperty); =*.~BG  
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InputStream input = httpConnection.getInputStream(); ,Vax&n+J  
//logResponseHead(httpConnection); 1~FOgk1;  
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byte[] b = new byte[1024]; QL/(72K  
int nRead; jd"@t*ZV  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 4@gG<QJW  
{ U>SShpmZA  
nStartPos += fileAccessI.write(b,0,nRead); T Z@]:e:"b  
//if(nThreadID == 1) Pm?KI<TH~  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (E3b\lST  
} y<3-?}.aZ  
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Utility.log("Thread " + nThreadID + " is over!"); RBd7YWo\|j  
bDownOver = true; 8W7J3{d  
//nPos = fileAccessI.write (b,0,nRead); I][*j  
} 1.hyCTnI  
catch(Exception e){e.printStackTrace ();} Ee#q9Cx^J  
} hfB%`x#akQ  
}  }v{LRRi  
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//打印回应的头信息 LOYk9m  
public void logResponseHead(HttpURLConnection con) G!##X: 6'  
{ 6|=
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for(int i=1;;i++) e%M;?0j  
{ =XQ%t @z0  
String header=con.getHeaderFieldKey(i); RP|`HkP-2  
if(header!=null) {YC@T(  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ]/6z; ~3U  
Utility.log(header+" : "+con.getHeaderField(header)); Ix}sK"}[n  
else e`s ~.ZF  
break; 4J?0bZ  
} G_JA-@i%  
} 372rbY  
u#~RkY7s  
; 2#y
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public void splitterStop() Tidn-2L73O  
{ t?gic9 q  
bStop = true; T!{w~'=F  
} fOrH$?  
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re<{ >  
} 
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/* P+sW[:  
**FileAccess.java 3?yg\  
*//文件访问(定位，写) @mBQ?;qlK  
package NetFox; l'qg8  
import java.io.*; D_7,m%Z:  
T-L||yE,h  
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public class FileAccessI implements Serializable{ Q&;9x?e  
?V=ZIGj  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ru%y  
RandomAccessFile oSavedFile; EZGIf/ 3  
long nPos; *^4"5X@  
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e*C(q~PQ  
public FileAccessI() throws IOException 6 "sSoj  
{ N+xP26D8  
this("",0); WH}y"W  
} I236RIq  
e T{ 4{  
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public FileAccessI(String sName,long nPos) throws IOException RqrdAkg  
{ P@B]

 
oSavedFile = new RandomAccessFile(sName,"rw"); reWot&;  
this.nPos = nPos; ^x,YW]AS}  
oSavedFile.seek(nPos); O/Crd/  
} t:Q*gWRh  
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{
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public synchronized int write(byte[] b,int nStart,int nLen) =T@1@w  
{ )
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int n = -1; <'*LRd$1  
try{ 0~S^
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oSavedFile.write(b,nStart,nLen); \b x$i*  
n = nLen;  kJ}`V  
} ~0$&3a<n1  
catch(IOException e) FZlWsp=  
{ oc`H}Wvn  
e.printStackTrace (); F4
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} n>YKa)|W`  
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return n; T5h H  
} 4[eXe$  
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} H{wl% G  
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/4Gt{ygSr  
/* jLluj   
**SiteInfoBean.java R/YqyT\SM  
*/ 5]0<9a  
package NetFox; %h@EP[\  
&8lZNv8;(p  
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public class SiteInfoBean { L,!?Nt\  
S1_RjMbYM  
#6=  
private String sSiteURL; //Site's URL rILYI;'o  
private String sFilePath; //Saved File's Path lf,5w  
private String sFileName; //Saved File's Name ms]sD3z/W+  
private int nSplitter; //Count of Splited Downloading File 7<R E_/]  
4r}51 N\  
?@86P|19  
public SiteInfoBean() ;Y, y4{H3  
{//nSplitter的缺省值为5 ~DwpoeYX  
//default value of nSplitter is 5 XL^GZ  
this("","","",5); <5051UEu  
} 2+XAX:YD  
;V!D:5U  
@VEb{ w[H  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) }K(TjZR  
{ 9*M,R,y  
sSiteURL= sURL; @yYkti;4-  
sFilePath = sPath; F^:3?JA_  
sFileName = sName; =s6 opL)  
this.nSplitter = nSpiltter; 59u}W 0  
l/5 hp.  
[/r(__.  
} ob]w;"  
^2rN>k,?  
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public String getSSiteURL() E1 2uZ$X  
{ ih3n<gXF  
return sSiteURL; SXh-A1t  
} XiWmV ?  
K&-"d/QuLg  
!N^@4*  
public void setSSiteURL(String value) m&3xJuKih  
{ ~} ~4  
sSiteURL = value; R;LP:,)  
} OyIw>Wfv  
"AqB$^S9t  
8oGRLYU N  
public String getSFilePath() 2 %]X+`+O  
{ AbM'3Mkz  
return sFilePath; HoAy_7-5  
} 2=}FBA,2  
x8|J-8A(  
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public void setSFilePath(String value) 2\$
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{ BgT*icd8d  
sFilePath = value; c71y'hnT  
} dE3) |%  
|-H&o]  
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public String getSFileName() %C]>9."  
{ zH r_!~  
return sFileName;  Z\sDUJ  
} '"s@enD0y  
%
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v$9y,^p@e  
public void setSFileName(String value) pgo$61  
{ DmcZta8n]  
sFileName = value; 8P`"M#fI  
} kx^/*~ex  
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*qq+jsA6wH  
public int getNSplitter() XWw804ir  
{ {;oPLr+Z  
return nSplitter;
(@YG~0  
} %TqC/c  
6eCCmIdaM  
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public void setNSplitter(int nCount) dh\P4  
{ =(^3}x  
nSplitter = nCount; +7}]E1Uf  
} j<$2hiI/?&  
} l,).p  
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/* !R$`+wZ62  
**Utility.java \)e'
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*/ 6LhTBV
 
package NetFox; wIgS3K  
Bw.i}3UT6  
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public class Utility { -\MG}5?!  
FI.\%x  
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public Utility() "N#Y gSr  
{ 8Fub<UhJ  
Dv6}bx(  
4M T 7`sr  
} wC*X4 '  
i/.6>4tE:  
//线程睡眠 UF|p';oom  
public static void sleep(int nSecond) m {}Lm)M  
{ 9BB=YnKE  
try{ HOi`$vX}N  
Thread.sleep(nSecond); - YBY[%jF>  
} E-FUlOG&  
catch(Exception e) A@'OJRc  
{ $~kA B8z  
e.printStackTrace (); W*G<X.Hf  
} QGz|*]  
} g)B]FH1  
|y*c9  
//日志 Rb;'O89Hj@  
public static void log(String sMsg) F"kAkX>3}  
{ zm# ?W  
System.err.println(sMsg); iow"n$/  
} 4Tc~b3\!Y  
/kG_*>.Z  
/_.|E]  
public static void log(int sMsg) IGgL7^MF  
{ ,: ^u-b|  
System.err.println(sMsg); ~"bVL[  
} *^r}"in  
} iDD$pd,e\  
fV~~J2IK  
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/* @9:uqsL  
**TestMethod.java +,l-Nz  
*/ 'fW-Y!k%  
package NetFox; 4e  
y>L
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06jQE2z2R  
public class TestMethod { ,)io5nZF  
bd`P0f?  
F[MFx^sT{  
public TestMethod() MfkZ  
{ ///xx/weblogic60b2_win.exe T>>c2$ x  
try{ _dU\JD  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); p}P-6&k,U  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); #z42C?V  
SiteFileFetch fileFetch = new SiteFileFetch(bean); cb bFw  
fileFetch.start(); d5-qZ{W  
} r<\u6jF  
catch(Exception e){e.printStackTrace ();} }2oc#0  
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ZC8wA;
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} ,u m|1dh  
DNi+"[~&P  
@nf
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public static void main(String[] args) DwF hK*  
{ Z:gyz$9w  
new TestMethod(); 7[7"A  
} JS77M-Ac  
} 92{\B- l  
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