http断点续传简单实现（java)

/* ["^? vhv  
**SiteFileFetch.java 6UKZ0~R  
*/ dym K@  
package NetFox; =&I9d;7  
import java.io.*; IOT-R!.5V  
import java.net.*; 4$+1&
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public class SiteFileFetch extends Thread { b4&l=^:e=  
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SiteInfoBean siteInfoBean = null; //文件信息Bean jS ?#c+9  
long[] nStartPos; //开始位置 ShesJj  
long[] nEndPos; //结束位置 4<V}Aj8l  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 |*$0~mA  
long nFileLength; //文件长度 bH.SUd)  
boolean bFirst = true; //是否第一次取文件 H/U.Bg 4  
boolean bStop = false; //停止标志 v\o m  
File tmpFile; //文件下载的临时信息 Z 4QL&?U  
DataOutputStream output; //输出到文件的输出流 
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） <?>tjCg'  
public SiteFileFetch(SiteInfoBean bean) throws IOException o~7D=d?R  
{ Tq?7-_MLC$  
siteInfoBean = bean; 5=#2@qp  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); $5:I~-mx  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); FsLd&$?T&  
if(tmpFile.exists ()) GL%)s?   
{ h S)lQl:^  
bFirst = false; 2]]}
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read_nPos(); h~lps?.#b  
} ot0g@q[3  
else 5PsjGvm.%  
{ Ya4yW9*  
nStartPos = new long[bean.getNSplitter()]; #mYe@[p@  
nEndPos = new long[bean.getNSplitter()]; \%&):OD1  
} 6 2#@Y-5  
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} (&SPMhs_|(  
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public void run() zZ,"HY=jN  
{ ++n_$Qug  
//获得文件长度 xR8y"CpE  
//分割文件 ~ mzX1[  
//实例FileSplitterFetch =h xyR;  
//启动FileSplitterFetch线程 #jJ0
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//等待子线程返回 ZUD{V  
try{ P?^%i  
if(bFirst) =ld!=II  
{ $_3)m  
nFileLength = getFileSize(); 6"?#E[ #[  
if(nFileLength == -1) !jf!\Uu[U  
{ ep4?;Qmho  
System.err.println("File Length is not known!"); W[R`],x`  
} WcQkeh3n  
else if(nFileLength == -2) Po&'#TC1  
{ # [ +n(  
System.err.println("File is not access!"); #&ei  
} +IMt$}7[  
else ,`PYU[  
{ $4*gi&  
for(int i=0;i<nStartPos.length;i++) EeHghq  
{ @Ko#nDEq  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); -/ G#ls|?  
} `n@;%*6/  
for(int i=0;i<nEndPos.length-1;i++) hXvC>ie(i  
{ ;66{S'*[  
nEndPos = nStartPos[i+1]; 3-oKY*jO  
} [)?9|yY"`  
nEndPos[nEndPos.length-1] = nFileLength; J:J/AgJuH  
} fda4M  
} ii&ckg>]z  
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//启动子线程 el\xMe^SY  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]TJ258P}  
for(int i=0;i<nStartPos.length;i++) 1;PI%++  
{ 97 ,Yq3  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), u1gD*4+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Nf)SR#;  
nStartPos,nEndPos,i); =dwy 4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "&{.g1i9  
fileSplitterFetch.start(); 6J_
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} ZuZCIqN  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), D^a(|L3;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); :wEy""*N0  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", q&}+O  
nEndPos = " + nFileLength); i9V,  
// fileSplitterFetch[nPos.length-1].start(); c$lZ\r"  
mN>(n+ly  
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//等待子线程结束 x0%yz+i{:  
//int count = 0; z`eMb  
//是否结束while循环 GXk |p8  
boolean breakWhile = false; kkW}:dBl  
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while(!bStop) 8Q"1I7U  
{ acgx')!c  
write_nPos(); E^A!k=>  
Utility.sleep(500); >vR2K^  
breakWhile = true; 6$kh5$[  
q: X^V$`  
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for(int i=0;i<nStartPos.length;i++) =GW[UnO  
{ m=Gb<)Y  
if(!fileSplitterFetch.bDownOver) ;Wa&Dg/5`  
{ Jl6lZd(Np  
breakWhile = false; dt>9mF q  
break; \.+:yV<$  
} ;)SWwhQ  
} Bj"fUI!dK  
if(breakWhile) m.\JO  
break; &;`E3$>  
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ZD7q

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//count++; ~3&hvm[IQ  
//if(count>4) dPxJ`8  
// siteStop(); xZM4CR9]*C  
} #_|O93HN'  
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System.err.println("文件下载结束！"); j,SZJ{ebXg  
} Dd,i^,4Gj  
catch(Exception e){e.printStackTrace ();} -1~o~yGE  
} AX'-}5T=  
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//获得文件长度 5sj$XA?5  
public long getFileSize() =;F7h @:  
{ FD~ UF;VQ  
int nFileLength = -1; ;g;1<? [  
try{ LU8:]zOY  
URL url = new URL(siteInfoBean.getSSiteURL()); ^QG<_Dm]  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); aR'~=t&;z1  
httpConnection.setRequestProperty("User-Agent","NetFox"); ori[[~OyB  
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int responseCode=httpConnection.getResponseCode(); .6I'V3:Kg  
if(responseCode>=400) :h/v"2uDN  
{ eAqpP>9n  
processErrorCode(responseCode); ITEf Q@#jU  
return -2; //-2 represent access is error =fdW H4  
} ?GtI.flV  
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String sHeader; ZR"qrCSw`  
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for(int i=1;;i++) tA,J~|+f:  
{ HD1/1?y!@q  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); WTjmU=<\  
//Utility.log(in.readLine()); vS[\j  
sHeader=httpConnection.getHeaderFieldKey(i); (<@`MPI\@  
if(sHeader!=null) iel@"E 4  
{ 9'(m"c_  
if(sHeader.equals("Content-Length")) "DH>4Q] d  
{ U!K#g_}  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); +x/vZXtOK  
break; >6@,L+-6r  
} &3xda1H  
} 
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else uq7/G|  
break; ^#K^WV  
} skTtGz8R[  
} .7:ecF
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catch(IOException e){e.printStackTrace ();} R9D2cu,{  
catch(Exception e){e.printStackTrace ();} 6+"gk(  
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Utility.log(nFileLength); =W2I0nr.  
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return nFileLength; =UWW(^M#[:  
} {sj{3Iu  
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//保存下载信息（文件指针位置） &OEBAtc/  
private void write_nPos() ;B(16&l=q  
{ qV,x)y:V  
try{ ,S@B[+VZ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); E9t8SclV  
output.writeInt(nStartPos.length); "Vp:Sq9y  
for(int i=0;i<nStartPos.length;i++) l8_RA  
{ fA[T5<66  
// output.writeLong(nPos); :Z_abKt  
output.writeLong(fileSplitterFetch.nStartPos); Ir*{IV
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output.writeLong(fileSplitterFetch.nEndPos); +qqCk  
} "{3|(Qs  
output.close(); PI,2b(`h_  
} Ml{4)%~Y7f  
catch(IOException e){e.printStackTrace ();} FFmXT/K"/j  
catch(Exception e){e.printStackTrace ();} ~Ga{=OM??  
} A`>^A]%  
5~(nHCf>  
l
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//读取保存的下载信息（文件指针位置） `krVfE;_O  
private void read_nPos() 8YgRJQZ!  
{ 78<fbN5}r  
try{ oz[G'[\}F  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); =}u?1~V  
int nCount = input.readInt(); i.eMrzJ|  
nStartPos = new long[nCount]; O'.{6H;t  
nEndPos = new long[nCount]; S&k/Pc  
for(int i=0;i<nStartPos.length;i++) oYJ<.Yxeb  
{ cf*~Gx_l  
nStartPos = input.readLong(); JS<w43/j  
nEndPos = input.readLong();
Ad>@8^  
} $?VYHkX  
input.close(); 6Bexwf<u  
} zzh7 "M3Qn  
catch(IOException e){e.printStackTrace ();} ]gF=I5jn]  
catch(Exception e){e.printStackTrace ();} w !<-e>  
} knb0_nA  
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9#~jlq(  
private void processErrorCode(int nErrorCode) Y`6<:8[?  
{ Gc5mR9pV   
System.err.println("Error Code : " + nErrorCode); g?Rq .py]!  
} MU:v& sk  
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HW'I$ .  
//停止文件下载 'dv
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public void siteStop() 98uMD  
{ w_LkS/  
bStop = true;
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for(int i=0;i<nStartPos.length;i++) CWB<I  
fileSplitterFetch.splitterStop(); |RqCI9N6  
+@7c:CAy(  
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} ,W/Y@Sc
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} z U*Mk  
//负责部分文件的抓取 AXnKhYlu  
**FileSplitterFetch.java (OavgJ+Y  
*/ D$w?  
package NetFox; -$@'@U  
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import java.io.*; t+^__~IX  
import java.net.*; @ Yo*h"s  
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public class FileSplitterFetch extends Thread { Y;dqrA>@  
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String sURL; //File URL 2uF'\y  
long nStartPos; //File Snippet Start Position {W%XSE  
long nEndPos; //File Snippet End Position oL!C(\ER
h  
int nThreadID; //Thread's ID 4Yt'I#*  
boolean bDownOver = false; //Downing is over }?O>.W,/  
boolean bStop = false; //Stop identical W*n|T{n  
FileAccessI fileAccessI = null; //File Access interface /R6\_oM  
.R@XstQ  
}wJH@'0+  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 0wF)bQv1  
{ GW7+#  
this.sURL = sURL; X
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this.nStartPos = nStart; E%Ko[G  
this.nEndPos = nEnd; fj9&J[
 
nThreadID = id; bz [?M}  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 BgB0  
} 1&Mpx!K*T  
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public void run() Kv#Q$$)r  
{ `nc=@" 1  
while(nStartPos < nEndPos && !bStop) n*#HokX  
{ _U,Hi?b"$}  
Wi~?2-!   
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try{ +]~}kvk:  
URL url = new URL(sURL); hxw6^EA  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); gnf4H V~  
httpConnection.setRequestProperty("User-Agent","NetFox"); ?]+!gz1  
String sProperty = "bytes="+nStartPos+"-"; >J:
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httpConnection.setRequestProperty("RANGE",sProperty); 8zjJshE/  
Utility.log(sProperty); _5OxESE  
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InputStream input = httpConnection.getInputStream(); SxkY ;^-U  
//logResponseHead(httpConnection); &7{yk$]*  
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byte[] b = new byte[1024]; M`)3(|4  
int nRead; EQ"+G[j~x  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Z8f?uF  
{ zP|^@Homk  
nStartPos += fileAccessI.write(b,0,nRead); r*FAUb`bG  
//if(nThreadID == 1) \(zUI  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^^YP kh6sS  
} ~ET XXu${I  
&F*eo`o}6  
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Utility.log("Thread " + nThreadID + " is over!"); N7)K\)DS!z  
bDownOver = true; 1DH P5q  
//nPos = fileAccessI.write (b,0,nRead); o}52Qio  
} c68,,rJO]i  
catch(Exception e){e.printStackTrace ();} ajf(Ii\/  
} Pv*]AF;9pQ  
} z1.vnGP  
/38XaKc{6  

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//打印回应的头信息  / w[Tu  
public void logResponseHead(HttpURLConnection con) yEkwdx5!(  
{ ^pqJz^PO.  
for(int i=1;;i++) AyOy&]g  
{ _Y)Wi[  
String header=con.getHeaderFieldKey(i); =t.T9'{  
if(header!=null) Xs~IoU  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ih: XC  
Utility.log(header+" : "+con.getHeaderField(header)); R\x3'([A5  
else
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break; 02YmV%  
} XXXQAY-,C  
} vu:] [2"0  
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public void splitterStop() !'
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{ yMpZ-b$*~  
bStop = true; \86N
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} |:L}/onK  
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} z]&?}o  
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/* {9cjitl  
**FileAccess.java zT>BC}~.b  
*//文件访问(定位，写) lx> ."rW  
package NetFox; (N9g6V  
import java.io.*; S.?DR3XLc  
%{?9#))  
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public class FileAccessI implements Serializable{ gOm8 O,  
}q,dJE  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 {W=5 J7  
RandomAccessFile oSavedFile; )G*xI`(@  
long nPos; W<$!H V$  
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public FileAccessI() throws IOException yl0;Jx?  
{ =VV><^uzdY  
this("",0); y~Mu~/s  
} 2AEVBkF;M  
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public FileAccessI(String sName,long nPos) throws IOException YdN]Tqc  
{ ?.Ip(g  
oSavedFile = new RandomAccessFile(sName,"rw"); %l!-rXp  
this.nPos = nPos; ZVrZkd`  
oSavedFile.seek(nPos); >Sb3]$$  
} s@6Jz\<E  
"/%o'Fq  

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public synchronized int write(byte[] b,int nStart,int nLen) 1*.*\4xo  
{ }]=@Y/p  
int n = -1; L-%'jR  
try{ m^w{:\p  
oSavedFile.write(b,nStart,nLen); w:mm@8N  
n = nLen; ZKM@U?PK  
} }T}xVd0  
catch(IOException e) :#D~j]pP  
{ as@? Kv  
e.printStackTrace (); ex66GJQe1  
} xqQK-?k  
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return n; &=XK:+  
} |
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} [X*u`J  
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/* k$>5v +r0  
**SiteInfoBean.java Zay%QNsb  
*/ $EzWUt  
package NetFox; {d.K)8\  
9!.S9[[N  
#)3 B  
public class SiteInfoBean { "2p\/VfA  
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'*Ld,`  
private String sSiteURL; //Site's URL }$ Kd-cj+  
private String sFilePath; //Saved File's Path CTxP3a9]  
private String sFileName; //Saved File's Name @uanej0q7  
private int nSplitter; //Count of Splited Downloading File |*Oi:)qt  
p7HLSB2Rp  
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public SiteInfoBean() M27H{}v  
{//nSplitter的缺省值为5 u4bVp+  
//default value of nSplitter is 5 qh6rMqq  
this("","","",5); WdB\n/BWB  
} Ey=}bBx  
JpxQS~VX  

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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) >8b%*f8R  
{ ) TRUx  
sSiteURL= sURL; O%haaL\  
sFilePath = sPath; c _!!DEe7  
sFileName = sName; ;--D?Gs]Qr  
this.nSplitter = nSpiltter; >(.Y%$9"E  
.Lu3LVS  
*z.rOY= 8  
} *LuRo  
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9,JWi{lIv  
public String getSSiteURL() Et0)6^-v  
{
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return sSiteURL; $PAAmaigi  
} !Ce!D0Tx  
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public void setSSiteURL(String value) EVC]B}  
{ M
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sSiteURL = value; ! h92dH  
} pMAP/..+2  
/Z,hQ>/  
*aFY+.;U`  
public String getSFilePath() 29m$S7[  
{ ^@{"a  
return sFilePath; *u",-n  
} ;tF&r1  
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@#$(Cs*{]  
public void setSFilePath(String value) p1K]m>Y{?  
{ ei{tW3 H$  
sFilePath = value; 5&O%0`t  
} (E,Ibz2G:e  
7upWM~H^  
yz5! >|EB  
public String getSFileName() :@eHV=|+>  
{ )xKW  
return sFileName; +r9neS.l  
} Nh}u]<B  
V!>j:"  
9v?@2sOoE  
public void setSFileName(String value) !2^~ar{2  
{ WuFBt=%  
sFileName = value; `w`F-ke]I  
} 9*huO#  
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public int getNSplitter() O0s!3hKu  
{ Jb^{o+s53  
return nSplitter; 29VX-45  
} xplV
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public void setNSplitter(int nCount) e+D]9wM8  
{ IV1Y+Z )  
nSplitter = nCount; Dln1 R[  
} 9%"`9j~H>  
} 1uCF9P ai  
>tx[UF@P@  
SM2
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/* r4DHALu#)  
**Utility.java qvK/}  
*/ <;O^3_'  
package NetFox; (DS"*4ty  
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)rt%.`  
public class Utility { SMJRoK3  
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public Utility() E^br-{|{  
{ h/5S2EB0!O  
9 wbQ$>G9  

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} &/ED.K  
RqP_^tB  
//线程睡眠 RyG6_G}  
public static void sleep(int nSecond) WSN^iDS
 
{ 0NKg
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try{ sR[!6[AA  
Thread.sleep(nSecond); )0ydSz`B  
} @rDBK] V  
catch(Exception e) *|<~IQg  
{
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e.printStackTrace (); K~I?i/P=z  
} dr+(C[=  
} vt^7:!r  
sQ,xTWdj  
//日志 lX)AbK]nb  
public static void log(String sMsg) !{+.)%d'g  
{ '`.-75T  
System.err.println(sMsg); v9Sk\9}S  
} 32?'jRN(ue  
/ o I 4&W  
/3K)$Er  
public static void log(int sMsg) O9/)_:Wdh  
{ .{*l,  
System.err.println(sMsg); M

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} -!\%##r7~  
} P=KhR&gwV~  
x<Gjr}  
NN1}P'6Ha  
/* D7JrGaF{  
**TestMethod.java $u'"C|>8  
*/ ;UM(y@  
package NetFox; S50}]5K  
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6)ln,{  
public class TestMethod { wet[f{c  
kGo2R]Dd[  
5`+9<8V  
public TestMethod() >1;jBx>Qy%  
{ ///xx/weblogic60b2_win.exe .UQ|k,,t  
try{ doHE]gC2Uz  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); .%e>>U>F  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); bv'>4a  
SiteFileFetch fileFetch = new SiteFileFetch(bean); law
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fileFetch.start(); kp*!  
} JGTsVa2  
catch(Exception e){e.printStackTrace ();} SA&(%f1d  
!ehjLFS?_  
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} 2IR
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|N% l at  
public static void main(String[] args) F[yofRN  
{ <!XunXh  
new TestMethod(); +6P[TqR  
} ab%I&B<b  
} v;9(FLtL  
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