http断点续传简单实现（java)

/* t~/:St  
**SiteFileFetch.java 0P9\;!Y  
*/ o&Xp%}TI  
package NetFox; XxS#~J?:_  
import java.io.*; &zX W  
import java.net.*; H/x0'  
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@qp6Y_,E[  
public class SiteFileFetch extends Thread { `v``}8tm  
8VMA~7^  
r+E!V'{C  
SiteInfoBean siteInfoBean = null; //文件信息Bean |xFA}
  
long[] nStartPos; //开始位置 ~rdS#f&R2  
long[] nEndPos; //结束位置 z}u`45W+  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 w a(Y[]V  
long nFileLength; //文件长度 8^y=YUT  
boolean bFirst = true; //是否第一次取文件 s_IFl5D]  
boolean bStop = false; //停止标志 _Fa\y ZX  
File tmpFile; //文件下载的临时信息 Jj>Rzj!m  
DataOutputStream output; //输出到文件的输出流 ~^Cx->l  
A'z]?xQR  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Ia}qDGqPp!  
public SiteFileFetch(SiteInfoBean bean) throws IOException h$!YKfhq}
 
{ ZY`9  
siteInfoBean = bean; Uq#2~0n>  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 1Ys=KA-!_x  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); yV:8>9wE8  
if(tmpFile.exists ()) (l{8Ixs  
{ {]]%0!n\  
bFirst = false; GEc-<`-  
read_nPos(); fGlvum  
} v9:J 55x  
else 20|_wAA5  
{ !<:Cd(bM  
nStartPos = new long[bean.getNSplitter()]; XKky-LeJ  
nEndPos = new long[bean.getNSplitter()]; %"Um8`]FVg  
} P(k*SB|D  
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Q^2dZXk~  
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} 9m$"B*&6G  
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public void run() 6)uBUM;i  
{ 5tbCx!tL  
//获得文件长度 0q"4\#4l  
//分割文件 `KA==;0  
//实例FileSplitterFetch *mp:#'  
//启动FileSplitterFetch线程 $5 mGYF]  
//等待子线程返回 3Jizv,?  
try{ yO)xN=o^\  
if(bFirst) }? / Blr  
{ B1 }-   
nFileLength = getFileSize(); /'jX_ V_$|  
if(nFileLength == -1) + m-88  
{ mc?I
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System.err.println("File Length is not known!"); yl~;!  
} _D{A`z  
else if(nFileLength == -2) hb3:,c(  
{ g@>llve{  
System.err.println("File is not access!"); '=E;^'Rl  
} u.X]K:Yow  
else [E a{);  
{ u>lt}0  
for(int i=0;i<nStartPos.length;i++) g,JfT^  
{ \[3~*eX6  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); h6D4CT  
} Ct)58f2  
for(int i=0;i<nEndPos.length-1;i++) "D.<~!  
{ ZMgsuzg  
nEndPos = nStartPos[i+1]; hO8xH +;  
} 1<_][u@  
nEndPos[nEndPos.length-1] = nFileLength; 1(BLdP3&  
} /io06)-/n  
}  N~$>| gn  
5HOl~E  
H^n@9U;[K
 
//启动子线程  wkZwtq  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ,gQl_Amvz  
for(int i=0;i<nStartPos.length;i++) $~FZJ@qa  
{ Hj{.{V  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 88_ef7w  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Bu=1-8@=qs  
nStartPos,nEndPos,i); iuY,E  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); xS1n,gTA  
fileSplitterFetch.start(); f5 bq)Pm&  
} vmAnBY  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), iZn0B5]ikj  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); x>EL|Q=?  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 7o+L  
nEndPos = " + nFileLength); ?3BcjD0  
// fileSplitterFetch[nPos.length-1].start(); n3~axRPO  
GoybkwFjZ  
/lC# !$9vz  
//等待子线程结束 +I3Vfv  
//int count = 0; Q")Xg:  
//是否结束while循环 r!Dk_|Cd  
boolean breakWhile = false; Hdew5Xn(:  
-yqgs>R(d  
A3/[9}(U  
while(!bStop) gDU!dT  
{ *`+zf7-f  
write_nPos(); N0w?c 5>  
Utility.sleep(500); 7e+C5W*9b  
breakWhile = true; FM6{%}4  
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95'+8*YCY  
for(int i=0;i<nStartPos.length;i++) {`SMxDevc}  
{ : b`N(]  
if(!fileSplitterFetch.bDownOver) O`y3H lc  
{ GLO3v. n;  
breakWhile = false; -b^dK)wR~  
break; es6YxMg  
} e}?Q&Lci  
} 4O-LLH  
if(breakWhile) [Kc?<3W  
break; j<kW+Iio  
nUj`#
%  
f1aZnl  
//count++; l3Zi]`@r  
//if(count>4) C%Lr3M;S'  
// siteStop(); tR>zB
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} "YI,  
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X\;:aRDS  
System.err.println("文件下载结束！"); Im~
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} rgIWM"  
catch(Exception e){e.printStackTrace ();} 9~W]D!m,  
} 8B*(P>  
_$AM=?P&  
o~XK*f=(  
//获得文件长度 A*DN/lG  
public long getFileSize() D-{*3?x  
{ 2om:S+3)2  
int nFileLength = -1; 4ekwmw(ox  
try{ j2,sI4  
URL url = new URL(siteInfoBean.getSSiteURL()); ZJ%NZAxy  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ppz3"5  
httpConnection.setRequestProperty("User-Agent","NetFox"); 
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;'{7wr|9  
int responseCode=httpConnection.getResponseCode(); Zm0VaOT$I  
if(responseCode>=400) "Y<
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{ qj~=qV0p  
processErrorCode(responseCode); Q8`V0E\~  
return -2; //-2 represent access is error 7vZO;FGtG  
} F6sQeU  
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String sHeader; =.8n K y  
4o}{3! m  
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for(int i=1;;i++)
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{ @Pcgm"H<  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); m"~ddqSMT  
//Utility.log(in.readLine()); +TqrvI.  
sHeader=httpConnection.getHeaderFieldKey(i); nV8'QDQ:Al  
if(sHeader!=null) TXi|  
{ >niv>+!N  
if(sHeader.equals("Content-Length")) t>"`rcg  
{ LujLC&S  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); i FZGfar?  
break; gf>H-718F  
} ;7s^slVzF  
} _{'[Uf/l  
else +m
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break; 
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} ZS+m}.,whQ  
} %mss{p!
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catch(IOException e){e.printStackTrace ();} j.]]VA  
catch(Exception e){e.printStackTrace ();} P0m9($JBD  
%"r9;^bj&<  
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Utility.log(nFileLength); w
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return nFileLength; |v7Je?yh  
} 4)e1K/PJ)  
/#vt\I<x  
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//保存下载信息（文件指针位置） 9 RDs`>v  
private void write_nPos() {v'eP[  
{ ?{'_4n3O  
try{ T`@brL  
output = new DataOutputStream(new FileOutputStream(tmpFile)); X% 05[N  
output.writeInt(nStartPos.length); Zocuc"j  
for(int i=0;i<nStartPos.length;i++) XFoSGq
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{ /#T{0GBXe  
// output.writeLong(nPos); kHr-UJ!  
output.writeLong(fileSplitterFetch.nStartPos); r4P%.YO+X  
output.writeLong(fileSplitterFetch.nEndPos); _k]R6V:  
} R5e[cC8o.  
output.close(); <VD7(j]'^  
} C<teZz8/w  
catch(IOException e){e.printStackTrace ();} 0B8Wf/j?M  
catch(Exception e){e.printStackTrace ();} <b"^\]
l  
} ngZq]8=o  

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//读取保存的下载信息（文件指针位置） )T9Cv8  
private void read_nPos() ~/A2:}Cp=  
{ 69$R.  
try{ ZhCd**  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 90uXJyW;d  
int nCount = input.readInt(); >[wxZ5))  
nStartPos = new long[nCount]; nmn/4>  
nEndPos = new long[nCount];  GpTZp#~;  
for(int i=0;i<nStartPos.length;i++) .$pe
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{ >dK0&+A  
nStartPos = input.readLong(); .BJoY <P*  
nEndPos = input.readLong(); 3(K.:376  
} 8!35 K  
input.close(); Vp; `!+z"  
} +mBS&FK  
catch(IOException e){e.printStackTrace ();} to).PI?  
catch(Exception e){e.printStackTrace ();} `EgX#  
} H2|'JA#v  
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.*6Nq
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private void processErrorCode(int nErrorCode) Dn<3#V  
{ )
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System.err.println("Error Code : " + nErrorCode); e=h-}XRC  
} !D1#3?L  
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~6t<`&f  
//停止文件下载 7l-MVn_8  
public void siteStop() fr`#s\JKw  
{ [@/p 8I  
bStop = true;  g4q{ ]  
for(int i=0;i<nStartPos.length;i++) i?d545. u  
fileSplitterFetch.splitterStop(); <v9IK$J  
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} U*{0,Ue'  
} W2-l_{  
//负责部分文件的抓取 Pi1LOCq  
**FileSplitterFetch.java G)YmaHeI;[  
*/ - s'W^(  
package NetFox; pvl];w  
eXsp0!v  
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import java.io.*; *MfH\X379  
import java.net.*; 'wFhfZB1!B  
?4wl  
]6^S:K_"  
public class FileSplitterFetch extends Thread { 4xT /8>v2|  
#\N8E-d  
/zh:7N  
String sURL; //File URL 1O,5bi>t7  
long nStartPos; //File Snippet Start Position 4E=QO!pVv  
long nEndPos; //File Snippet End Position Chl^LEN:  
int nThreadID; //Thread's ID !oi {8X@  
boolean bDownOver = false; //Downing is over 9ec?L  
boolean bStop = false; //Stop identical ye(av&Hn  
FileAccessI fileAccessI = null; //File Access interface %VB
4/~ "  
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;~r-P$kCY  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 4sSw7`  
{ }s?w-u+(c6  
this.sURL = sURL; ?/T=Gk  
this.nStartPos = nStart; |1H9,:*%  
this.nEndPos = nEnd; n|WSnm,W  
nThreadID = id; O0rvr$.  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 )%p46(]  
} H(Wiy@cJn  
\s)$
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public void run() 9a@S^B>  
{ ^PE|BCs  
while(nStartPos < nEndPos && !bStop) (qR;6l  
{ \;_tXb}F  
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try{ )(.g~Q:  
URL url = new URL(sURL); {4SaSv^/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); z^*g2J,  
httpConnection.setRequestProperty("User-Agent","NetFox"); }+S
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String sProperty = "bytes="+nStartPos+"-"; *!%n`BR '  
httpConnection.setRequestProperty("RANGE",sProperty); sRBfLN2C  
Utility.log(sProperty); 9MJ:]F5+  
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9 4bDJy1  
InputStream input = httpConnection.getInputStream(); 1NZp
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//logResponseHead(httpConnection); L~h:>I+pG  
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byte[] b = new byte[1024]; nfZe"|d  
int nRead; ^h=gaNL  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) {
=Ji2k0U'  
{ /EQ^-4yr  
nStartPos += fileAccessI.write(b,0,nRead); !"/"Mqs3$  
//if(nThreadID == 1) 8z|]{XW{  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); OcpvY~"Pr  
} -/B*\X
[  
&)Zv>P8z`  
6^jrv [d  
Utility.log("Thread " + nThreadID + " is over!"); ;D-k\kv  
bDownOver = true; Omn$O>  
//nPos = fileAccessI.write (b,0,nRead); hxJKYU^%m  
} +3AX1o%p,#  
catch(Exception e){e.printStackTrace ();} QTF1~A\  
} HnFH|H<Uf  
} QA~F  
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Z s|*+[  
//打印回应的头信息 (I;81h`1G  
public void logResponseHead(HttpURLConnection con) QCDica `+*  
{  h)W#  
for(int i=1;;i++) o[JZ>nm  
{ O
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String header=con.getHeaderFieldKey(i); *j<#5=l  
if(header!=null) U+ Yu_=o{  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 6 3PV R"  
Utility.log(header+" : "+con.getHeaderField(header)); ;InMgo,  
else &'DR`e O)  
break; D8B\F5..c#  
} ]RadwH"0!  
} >D##94PZ  
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public void splitterStop() )B-[Q#*A-  
{ #@V<{/;49  
bStop = true; e50xcf1u  
} 8eh3K8tL#  
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#jxPh!%9  
} p}I\H ^"8+  
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/* Mw+ l>92  
**FileAccess.java 2.@IfBF6  
*//文件访问(定位，写) JX>`N5s  
package NetFox; $
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import java.io.*; {pre|r\  
(B@\Dw8^  
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public class FileAccessI implements Serializable{ 6&LmR75C  
XdlA)0S)  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 +#UawYLJ  
RandomAccessFile oSavedFile; [z_ztK1  
long nPos; xu]Kt+QnSk  
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1B 0[dK2N  
public FileAccessI() throws IOException n#?y;Y\  
{ +uNMyVH  
this("",0); p? VDBAx  
} wJgH15oB  
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x=\W TC  
public FileAccessI(String sName,long nPos) throws IOException hSps9*y  
{ 0;w 4WJJ  
oSavedFile = new RandomAccessFile(sName,"rw"); u,=?|M\  
this.nPos = nPos; v$;URF%^  
oSavedFile.seek(nPos); a7b1c!  
} DbR!s1ux  
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x>4p6H{]0'  
public synchronized int write(byte[] b,int nStart,int nLen) 3RlNEc%)  
{ lF7".  
int n = -1; NUh%\{  
try{ NP!LBB)=Y  
oSavedFile.write(b,nStart,nLen); g>b{hkIXg  
n = nLen; Az?^4 1r8  
} VS~+W
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catch(IOException e) ~
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{ 66MUrNW  
e.printStackTrace (); PCH$)F4^  
}  Cz&t*i/  
* +6Z^7  
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return n; 5lwMc0{/3  
} "r@G V5ED  
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} VhnIr#L+  
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/* xj]^<oi<  
**SiteInfoBean.java Efpju(   
*/ anKflt3  
package NetFox; 3Zpq#  
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public class SiteInfoBean { bXM&VW?OP  
\4fuC6d2  
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private String sSiteURL; //Site's URL i8*(J-M  
private String sFilePath; //Saved File's Path \2Q#'  
private String sFileName; //Saved File's Name R=iwp%c(  
private int nSplitter; //Count of Splited Downloading File ?2gXF0+~Y2  
r. rzU  
&< FKcrZ,  
public SiteInfoBean() R_:lp\S&  
{//nSplitter的缺省值为5 ;jKLB^4nX  
//default value of nSplitter is 5 fNrpYR X  
this("","","",5); Psf{~ (Ii  
} zCS }i_ p  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 3r?T|>|  
{ 3n_t^=  
sSiteURL= sURL; ,RAP_I!_x  
sFilePath = sPath; a]8W32  
sFileName = sName; XHJ/211  
this.nSplitter = nSpiltter; 6jov8GIAt  
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*~UK5Brf1  
} z4]z3U<}3]  
:p
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public String getSSiteURL() 9T2y2d!X  
{ x|Ms2.!  
return sSiteURL; xHkxrXqeI  
} A(+V{1L'  
Hm~.u.)\.  
iQiXwEAi[  
public void setSSiteURL(String value) cA90FqUH  
{ Yqt
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sSiteURL = value; Yic4|N?u  
} Gy'/)}}Z  
=ATQ2\T$m  
=6qSo @  
public String getSFilePath() K@"B^f0mU  
{ >Gvd?r  
return sFilePath; kWCxc0  
} #zb67mg~  
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P;IM -]  
public void setSFilePath(String value) l5enlYH  
{ k/Q8:qA  
sFilePath = value; sv!6zJs  
} [|C  
zgxMDLH  
MiMDEe%f%  
public String getSFileName() Ud#xgs'  
{ 1b2xWzpG  
return sFileName; pT:6A[&  
} N=@8~{V.  
3Z}KRsp3  
i`w&{WTRQ  
public void setSFileName(String value) 4`?WdCW8  
{ WjvgDNk  
sFileName = value; 6x16?x  
} u*T#? W?  
8;3I:z&muQ  

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public int getNSplitter() R{9G$b1Due  
{ ?:7$c  
return nSplitter; OHH\sA  
} <CS,v)4,nH  
@8cn<+"b  
i06|P I  
public void setNSplitter(int nCount) T4;gF
6(0]  
{ {CgF{7`  
nSplitter = nCount; U6YQ*%mZ_  
} \.=,}sV2Z  
} L~Xzo  
:M@#.  
c$;Cpt@-j  
/* byk9"QeY\  
**Utility.java {@t6[g++  
*/ '*
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package NetFox; aOmQ<N]a  
^W0eRT  
XU`vs`/  
public class Utility { "OrF81  
?Elt;wL(  
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public Utility() 'pT8S  
{ k!g%vx  
ca'c5*Fs  
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} 6'.
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e8)8QmB{o  
//线程睡眠
u X(#+  
public static void sleep(int nSecond) kM
76?M  
{ @CA{uP;  
try{ ]QF*\2b-I2  
Thread.sleep(nSecond); VB=jKMi  
} `bNLmTS  
catch(Exception e) 'D^@e0.3  
{ a.XMeB  
e.printStackTrace (); jq(rnbV  
} F^!_!V B  
} ~AcjB(  
_$T.
N  
//日志 D\z`+TyJ  
public static void log(String sMsg) p<Vj<6.=?  
{ y6>fK@K~  
System.err.println(sMsg); ~@D{&7@  
} #ahe@|E'Y  
z+j3j2  
7C~g?1  
public static void log(int sMsg) $T*g@]   
{ 8HDI]  
System.err.println(sMsg); ^B(:Hv}G(:  
} Z07SK 'U  
} cXt]55"  
ezhK[/E=  
}t1J`+x%  
/* Qt=OiKZ  
**TestMethod.java W'Y#(N[ktP  
*/ GOX2'N\h^  
package NetFox; fczH^+mI  
!PEP`wEKdp  
e @|uG%  
public class TestMethod { -D wO*f  
Ots]y  
S\6.vw!'
 
public TestMethod() \WM"VT  
{ ///xx/weblogic60b2_win.exe +VO(6Jn  
try{ %}Z1KiRiX  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); |N5|B Q(y$  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); o_.`&Q6n  
SiteFileFetch fileFetch = new SiteFileFetch(bean); vk3C&!M<a  
fileFetch.start(); Bv^5L>JZ/  
} .QDeS|l  
catch(Exception e){e.printStackTrace ();} P5Pb2|\*
 
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} (q=),3/<pU  
(6i.>%|_  
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public static void main(String[] args) ;2547b[]  
{ @E?o~jO(e  
new TestMethod(); &xS] ;Fr  
} mz3Dt>  
} ;<BMgO}N  
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