http断点续传简单实现（java)

/* 9tk}_+  
**SiteFileFetch.java T*|?]k 8@*  
*/ AUzJ:([V  
package NetFox; '00DUUa  
import java.io.*; .Uha%~%  
import java.net.*;
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public class SiteFileFetch extends Thread { JFR,QUT  
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SiteInfoBean siteInfoBean = null; //文件信息Bean V@e0VV3yx%  
long[] nStartPos; //开始位置 @2kt6 W  
long[] nEndPos; //结束位置 >SSF:hI"J  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 SYa!IL-B  
long nFileLength; //文件长度 /ExnW >wT  
boolean bFirst = true; //是否第一次取文件 3PI{LU  
boolean bStop = false; //停止标志 ^9qncvV
 
File tmpFile; //文件下载的临时信息 *RN*Bh|$  
DataOutputStream output; //输出到文件的输出流 XW5r@
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） RrKs!2sCT  
public SiteFileFetch(SiteInfoBean bean) throws IOException 7Q
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{ >*vI:MG8  
siteInfoBean = bean; e,:@c3I  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); e?RHf_d3T-  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ?6tuo:gP  
if(tmpFile.exists ()) 6i{W=$RQ  
{ CQ#p2  
bFirst = false; Jq/([
  
read_nPos(); E83{4A4  
} ;Q? Qwda  
else B5J=q("P  
{ #sAEIk/  
nStartPos = new long[bean.getNSplitter()]; Ex
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nEndPos = new long[bean.getNSplitter()]; .NwHr6/s*  
} *8X: fq  
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} g0_8:Gs}^  
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public void run() YX@[z 5*  
{ YuLW]Q?v  
//获得文件长度 'OkF.bs  
//分割文件 M)Ogb'@#  
//实例FileSplitterFetch 
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//启动FileSplitterFetch线程 u=RF6V|  
//等待子线程返回 s.Yywy  
try{ ? 0nbvV5v7  
if(bFirst) GZ*cV3Y`&  
{ }$81FSKh  
nFileLength = getFileSize(); ,%>/8*  
if(nFileLength == -1) b_cD >A  
{ ,58D=EgFy  
System.err.println("File Length is not known!"); DkQy.  
} sh E>gTe  
else if(nFileLength == -2) gbQrSJs!Zh  
{ hZc$`V=R  
System.err.println("File is not access!"); 8(5}Jo+  
} g^4'42UX  
else 0j_`7<,:  
{ oy#Qj3M8=  
for(int i=0;i<nStartPos.length;i++) m_' 1yX@  
{ ^MQ7*g6o  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 9M<qk si  
} }3=]1jH6  
for(int i=0;i<nEndPos.length-1;i++) DoNbCVZ  
{ Fag%#jxI  
nEndPos = nStartPos[i+1]; o;
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} 
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nEndPos[nEndPos.length-1] = nFileLength; !W .ooy5(  
} 3%!d&j>v  
} @ 5|F:J  
iS=}| 8"  
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//启动子线程 V= !!;KR0  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; |HhUU1!  
for(int i=0;i<nStartPos.length;i++) Y2QlK1.8V  
{ ^hR
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), b":cj:mxL  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), LIirOf~e;!  
nStartPos,nEndPos,i); 5Y_)%u  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); {b=]JPE  
fileSplitterFetch.start(); "4oY F:h  
} *d?,i-Q.+  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), q%8,@xg  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); zD7\Gv  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", s?7g3H5#0k  
nEndPos = " + nFileLength); Abd&p N  
// fileSplitterFetch[nPos.length-1].start(); Mm+_>   
V!a\:%#^Y  
y]+i.8[  
//等待子线程结束 *:aJlvk  
//int count = 0; shjS^CP  
//是否结束while循环 ORyFE:p$  
boolean breakWhile = false; E@Q+[~H}  
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while(!bStop) PIsMx-i0  
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write_nPos(); o!gl :izb  
Utility.sleep(500); ~4`LOROC  
breakWhile = true; iRBUX`0  
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for(int i=0;i<nStartPos.length;i++) m}'kxZTOm  
{ %q`_vtUT  
if(!fileSplitterFetch.bDownOver) RxjC sjg  
{ @s b\0}  
breakWhile = false; q6%jCt2'  
break; 'Oyz/P(p  
} cAC]%~orx  
} Y2"X;`<  
if(breakWhile) wFnIM2a,  
break; R%"wf   
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//count++; pGc_Klq  
//if(count>4) hg/G7Ur"  
// siteStop(); *[) b}?  
} 5<0&y3  
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System.err.println("文件下载结束！");  Cdin"  
} ]bz']`  
catch(Exception e){e.printStackTrace ();} Mm;kB/1  
} /EZF5_`bT  
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//获得文件长度 _?x*F?5=
 
public long getFileSize() m}54yo  
{ [y7BHikX)  
int nFileLength = -1; 6FFQoE|n
 
try{ )hGRq'WA=  
URL url = new URL(siteInfoBean.getSSiteURL()); U3}r.9/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Y6~/H  
httpConnection.setRequestProperty("User-Agent","NetFox"); w+)MrB-}  
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int responseCode=httpConnection.getResponseCode(); sgW*0o  
if(responseCode>=400) <7NY.zvwk]  
{ =;#+8w=^  
processErrorCode(responseCode); TRW{`b[  
return -2; //-2 represent access is error 9tDo5 29  
}  yr9%,wwN  
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String sHeader; F'^6ra9  
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4
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for(int i=1;;i++) D[yOFJ~p)  
{ Cbv$O o*  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); vPz$jeA  
//Utility.log(in.readLine()); 9%55R >s$  
sHeader=httpConnection.getHeaderFieldKey(i); 2+y<&[A8U  
if(sHeader!=null) D/[(}o(  
{ r`Y[XzT9  
if(sHeader.equals("Content-Length")) biLx-F c  
{ 6c>cq\~E  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); puEuv6F  
break; BQmH
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} 1AiqB Rs  
} cy T,tN  
else \wwY?lOe  
break; MHar9)$}  
} =m]|C1x  
} ' P5ttI#|  
catch(IOException e){e.printStackTrace ();} xXkP(^ Y  
catch(Exception e){e.printStackTrace ();} fn(< <FA)  
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Utility.log(nFileLength); b{q-o <Q  
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return nFileLength; {6d)|';%  
} TN!8J=sx.  
.;nU" a3'  
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//保存下载信息（文件指针位置） GIG\bQSv2  
private void write_nPos() wtlIyE  
{ 8ExEhBX8  
try{ 9+><:(,  
output = new DataOutputStream(new FileOutputStream(tmpFile)); av|r^zc  
output.writeInt(nStartPos.length); m?wPZ^u  
for(int i=0;i<nStartPos.length;i++) =M39I&N  
{ 6xI9%YDy  
// output.writeLong(nPos); MtWzGE=?  
output.writeLong(fileSplitterFetch.nStartPos); Z{&dzc  
output.writeLong(fileSplitterFetch.nEndPos); u~[=5r  
} {-?^j{O0.  
output.close(); JAEn 72  
} 7tbM~+<0  
catch(IOException e){e.printStackTrace ();} g>].m8DZ'  
catch(Exception e){e.printStackTrace ();} phkfPvL{  
} `?@7T-v  
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//读取保存的下载信息（文件指针位置） y8~/EyY|^  
private void read_nPos() m][i-|@M  
{ 5ZpU><y  
try{ ).IB{+  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); F<R+]M:fa  
int nCount = input.readInt(); [3KP@'52k  
nStartPos = new long[nCount]; ^xz*%2@  
nEndPos = new long[nCount]; B+)HDIPa-  
for(int i=0;i<nStartPos.length;i++) 2GRL`.1  
{ VSf<(udGr  
nStartPos = input.readLong(); 8n
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nEndPos = input.readLong(); ,e]|[,r#5  
} 9:[L WT&  
input.close(); B}OM:0  
} _o,Mji|  
catch(IOException e){e.printStackTrace ();} O4Z_v%2M  
catch(Exception e){e.printStackTrace ();} LHJ}I5zv  
} ^)wTCkH&y  
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private void processErrorCode(int nErrorCode) }fqz8'E9  
{ >v\t> [9t  
System.err.println("Error Code : " + nErrorCode); uu5L9.i9  
} (j>a?dKDS  

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//停止文件下载 nogdOGo  
public void siteStop() ^/`W0kT  
{ +c&oF,=}!P  
bStop = true; a%FM)/oI|T  
for(int i=0;i<nStartPos.length;i++) r0xmDJ@y  
fileSplitterFetch.splitterStop(); LN!e_b  
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} P84uEDY  
} 8Pgw_ 21N1  
//负责部分文件的抓取 BNj@~uC{  
**FileSplitterFetch.java ZjB]pG+  
*/ R}T8cVxc  
package NetFox; Y<vHL<G  
}I )%Gw  
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import java.io.*; :_
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import java.net.*; |L}1@0i  
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public class FileSplitterFetch extends Thread { gL/D| =  
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String sURL; //File URL <meQ  
long nStartPos; //File Snippet Start Position KFuPgp  
long nEndPos; //File Snippet End Position |mS-<e8LY4  
int nThreadID; //Thread's ID 6\BZyry3*  
boolean bDownOver = false; //Downing is over C2a2K={  
boolean bStop = false; //Stop identical K6BP~@H_D  
FileAccessI fileAccessI = null; //File Access interface (gQr?K  
kWZ@v+Mk3  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :4\=xGiY  
{ l.iT+T  
this.sURL = sURL; Quts~Q  
this.nStartPos = nStart; nmN3Z_  
this.nEndPos = nEnd; cxig<W  
nThreadID = id; ?LAiSg=eq  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Z!81\5  
} fvNj5Vq:  

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public void run() +U^H`\EUr  
{ Q&?^eOI&#(  
while(nStartPos < nEndPos && !bStop) f [DZ  
{ UNOKK_  
Ij{ K\{y  
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try{ /hv2=A  
URL url = new URL(sURL); h(4&!x  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); AK_,$'f  
httpConnection.setRequestProperty("User-Agent","NetFox"); Sdr,q9+__  
String sProperty = "bytes="+nStartPos+"-"; .Y*jL&!  
httpConnection.setRequestProperty("RANGE",sProperty); N2
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Utility.log(sProperty); _7bQR7s  
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InputStream input = httpConnection.getInputStream(); $*S&i(z  
//logResponseHead(httpConnection); 9\S,$A{{*  
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byte[] b = new byte[1024]; zEMZz$Y  
int nRead; x T{s%wE  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) I*`;1+`  
{ GS@Zc2JPF  
nStartPos += fileAccessI.write(b,0,nRead); fpA%
:V  
//if(nThreadID == 1) gnWEsA\!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); r=4vN=:  
} vo!QJ  
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Utility.log("Thread " + nThreadID + " is over!"); /$=<RUE  
bDownOver = true; m+=L}[  
//nPos = fileAccessI.write (b,0,nRead); Uip-qWI  
} h}n?4B~Gi  
catch(Exception e){e.printStackTrace ();} ('oA{,#L  
} r-'CB  
} W6!o=()  
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//打印回应的头信息 E(miQ  
public void logResponseHead(HttpURLConnection con) y.,li<  
{ z>A;|iL  
for(int i=1;;i++) D0*+7n3  
{ lDVw2J'p  
String header=con.getHeaderFieldKey(i); q!Q*T^-rO  
if(header!=null) |rL#HG  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); *Q!I^]CR  
Utility.log(header+" : "+con.getHeaderField(header)); iL8:I)z  
else 8o\KF(I  
break; )>r sX)  
} B{2WvPX~q  
} bS&XlgnKi  
#VU>Z|$@N  
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public void splitterStop() #QM9!k@9k  
{ !9]q+XefJ  
bStop = true; L 4Sa,ZL  
} 9w}_CCj3  
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} 
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/* }:1*@7eR  
**FileAccess.java L5n/eg:Q  
*//文件访问(定位，写) fIii  
package NetFox; @s8wYcW  
import java.io.*; #]}]ZE  
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public class FileAccessI implements Serializable{ /ULO#CN?;  
 E-L>.tD  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 IcUE=J  
RandomAccessFile oSavedFile; wY{!gQ  
long nPos; ; -,VJCPi  
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public FileAccessI() throws IOException ey ?paT  
{ ]>oI3
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this("",0); mt]50}eK  
} $&KiN82,  
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public FileAccessI(String sName,long nPos) throws IOException nna boD  
{ 2UrE>_  
oSavedFile = new RandomAccessFile(sName,"rw"); K?gO]T{6  
this.nPos = nPos; [9,34/i  
oSavedFile.seek(nPos); C3-I5q(V]  
} %+ur41HM  
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public synchronized int write(byte[] b,int nStart,int nLen) l(uV@_3  
{ a~A"uLBR  
int n = -1; '$y.`/$  
try{ XBN,{  
oSavedFile.write(b,nStart,nLen); *$9Rb2}kK  
n = nLen; 8c'5P  
} TF-a1z  
catch(IOException e) UmOK7SPi  
{ R0bWI`$Z  
e.printStackTrace (); c'uDK>  
} WlRaD%Q  
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return n; z]n&,q,5g  
} g#r,u5<*?  
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} jGFDj"Y  
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/* ydf;g5OZ  
**SiteInfoBean.java P;[>TCs ]8  
*/ i$dF0.}Q  
package NetFox; e*hCf5=-  
l4Qv$  
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public class SiteInfoBean { ?oulQR6:  
P/ 7aj:h~P  
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private String sSiteURL; //Site's URL _0!<iN L  
private String sFilePath; //Saved File's Path &d&nsQ
 
private String sFileName; //Saved File's Name HVaKy+RU  
private int nSplitter; //Count of Splited Downloading File ?v$1Fc55  
_NB8>v
  
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public SiteInfoBean() <:I]0|[  
{//nSplitter的缺省值为5 B+2Jea,N  
//default value of nSplitter is 5 5gH'CzU?  
this("","","",5); (qg~l@rf  
} 5gbD|^ij  
[Ontip  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) P(Z\y^S  
{ .tt=\R  
sSiteURL= sURL; &T[BS;  
sFilePath = sPath; kYU!6t1  
sFileName = sName; VQHQvFRZ)  
this.nSplitter = nSpiltter; ?PDrj/: *  
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} H
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Mp)|5<%  
public String getSSiteURL() nQM7@"R  
{ NK|m7(
  
return sSiteURL; H`Ld,E2ex&  
} 8b:\@]g$  
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public void setSSiteURL(String value) C^!ej"  
{ DY!mq91  
sSiteURL = value; Ll'!aar,  
} (]*!`(_b  
MD=VR(P?eq  
;P2(C >|  
public String getSFilePath() q<!KtI4  
{ 6Rc%P)6  
return sFilePath; $,#,yl ol  
} J&jig?t  
O!.mc=Gx7  
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public void setSFilePath(String value) ,Z p9,nf  
{ X^ZUm  
sFilePath = value; qr[+^*Ha  
} {GM8}M~D&  
}Q%fY&#(bp  
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public String getSFileName() =OU]<%  
{ ZeP3 Yjr3  
return sFileName; N~@VZbS(6  
} V0'_PR@;  
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_
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public void setSFileName(String value) 
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{ 1q(o3%   
sFileName = value; C*fSPdg?  
} d( +E0  
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public int getNSplitter() ."\&;:ZNv  
{ M/^kita  
return nSplitter; 'hw_ew   
} 6 w:@i_2^  

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public void setNSplitter(int nCount) J>Uzd, /  
{ 8GD!]t#  
nSplitter = nCount; p$A`qx<M_  
} h2C1'+Q{9  
} +: oD?h  
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>J[Wd<~t  
/* *|DIG{  
**Utility.java =#c?g Wb56  
*/ I+^B]@"  
package NetFox; l TJqWSV=f  
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* 5Y.9g3)Q  
public class Utility { c(<,qWH  
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public Utility() v|v^(P,o  
{ C^x+'. ^N  
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} _,2P4  
.h8%zB#|i  
//线程睡眠 ToHCS/J59  
public static void sleep(int nSecond) ,~_)Cf#CB  
{ t $+
46**  
try{ SEc3`y;j%  
Thread.sleep(nSecond); =Xc[EUi<;g  
} c=T^)~$$  
catch(Exception e) Sr`gQ#b@r}  
{ zaVDe9B,7  
e.printStackTrace (); _~`\TS8  
} *YFe  
} G/Xa`4"_  
43;@m}|7$  
//日志 Y@S?0  
public static void log(String sMsg) .bYDj&]P{  
{ 'sL>U$(  
System.err.println(sMsg); 2>l:: 8Pp  
} t_q`wKDE  
ZL`G<Mo;.  
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public static void log(int sMsg) Hize m!  
{ 6SMGXy*]^  
System.err.println(sMsg); }Vpr7_  
} u|=G#y;3  
} Oifu ?f<r  
1a)NM#  
jG0{>P#+  
/* Xz=MM0o  
**TestMethod.java rSD!u0c[  
*/ +SmcZ^\OZ  
package NetFox; zJ#e3o.  
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?'K}bmdt}.  
public class TestMethod { & CiUU  
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public TestMethod() ~$f+]7  
{ ///xx/weblogic60b2_win.exe '!!w|kd  
try{ Wx&AY"J  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); *0y+=,"QU  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); S zOB{  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 8 F'i5i  
fileFetch.start(); 1{%EQhNd  
} yg "u^*r&  
catch(Exception e){e.printStackTrace ();} Xu$xO(  
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+b]g;  
} ' %OQd?MhL  
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&{* [7Ad  
public static void main(String[] args) bG>pm|/  
{ qqSk*oH~  
new TestMethod(); !cLX1S  
} O@3EJ
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} K,' ]G&K  
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