http断点续传简单实现（java)

/* n>>Qn&ym  
**SiteFileFetch.java -n80&  
*/ G\de2Q"d:O  
package NetFox; r|u MovnV  
import java.io.*; N$>^g"6o  
import java.net.*; aj^wRzJ}zA  
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public class SiteFileFetch extends Thread { _Q[$CcDEE  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ;r[@v347  
long[] nStartPos; //开始位置 HlvuW(,x=  
long[] nEndPos; //结束位置 RTh`ENCKR  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 _tTNG2  
long nFileLength; //文件长度 gKYfQ+  
boolean bFirst = true; //是否第一次取文件 "ZM4F?x  
boolean bStop = false; //停止标志 E_e6^Sk5B(  
File tmpFile; //文件下载的临时信息 .mLK`
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DataOutputStream output; //输出到文件的输出流 4%nE*H%  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Zwz&rIQpT  
public SiteFileFetch(SiteInfoBean bean) throws IOException ",7Q  
{ *!s;"U  
siteInfoBean = bean; #|&Sc_#4)  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 1i[FY?6`dh  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); nw>8GivO  
if(tmpFile.exists ()) #9-P%%kQ  
{ (0YZZ93  
bFirst = false; SN7"7joP<  
read_nPos(); InXn%9]p]  
} #txE=e"&o  
else z|EEVNFd&  
{ Sz- Jy:j  
nStartPos = new long[bean.getNSplitter()]; $6OkIP.  
nEndPos = new long[bean.getNSplitter()]; WmY``  
} ~cTN~<{dq  
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} ;r_F[E2z  
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public void run() x8S7oO7  
{ -gSUjP  
//获得文件长度 ])xx<5Jt4  
//分割文件 h$4Hw+Yxs]  
//实例FileSplitterFetch h%}/Cmx[  
//启动FileSplitterFetch线程 qlL`jWJ  
//等待子线程返回 sl]_M  
try{ R" ;xvo*  
if(bFirst) ;;L[e]Z  
{ 1 $/%m_t  
nFileLength = getFileSize(); ~0beuK&p  
if(nFileLength == -1) kY*rb_2j  
{ }VS5gxI1.  
System.err.println("File Length is not known!"); yW$0\E6<r  
} N"nd*?  
else if(nFileLength == -2) DxUKUE  
{ |<:vY  
System.err.println("File is not access!"); yE}}c{hSn  
} 4"gM<z  
else {}3${  
{  IiY/(N+J  
for(int i=0;i<nStartPos.length;i++) dZi"$ g  
{ Z?wU  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); e,t(q(L  
} 1P~X8=9h  
for(int i=0;i<nEndPos.length-1;i++) h }B% /U  
{ *:Z
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nEndPos = nStartPos[i+1]; `s\?w5[  
} g!rQ4#4  
nEndPos[nEndPos.length-1] = nFileLength; .Fdgb4>BXX  
} :2 *g~6  
} l c+g&f  
9FB19  
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//启动子线程 6@rMtQfI  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; "rx-_uK*  
for(int i=0;i<nStartPos.length;i++) O^oWG&Y;v  
{ z^'gx@YD*v  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 9I6
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ILGMMA_2  
nStartPos,nEndPos,i); :Zlwp6  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); i\,-oO  
fileSplitterFetch.start(); Wf|Q$MHos  
} Tj:B!>>  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), `$ 6rz  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); tfj:@Z5&$C  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 6}d.5^7lr  
nEndPos = " + nFileLength); uScMn/%  
// fileSplitterFetch[nPos.length-1].start(); R%?9z 8-  
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//等待子线程结束 #qK:J;Sn3  
//int count = 0; |y
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//是否结束while循环 f&Gt|  
boolean breakWhile = false; }H^+A77v  
KV(Q;~8"X  
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while(!bStop) bbE!qk;hEP  
{ U~:-roQ(\  
write_nPos(); 17%Mw@+  
Utility.sleep(500); hb}+A=A=+  
breakWhile = true; g:hjy@ w  
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for(int i=0;i<nStartPos.length;i++) ~"nxE  
{ .+$Q<L  
if(!fileSplitterFetch.bDownOver) <3LbNFP  
{ 45@^L's  
breakWhile = false; YtmrRDQs  
break; .(K)?r-g5  
} e|"WQ>  
} Y3Yz)T}UkS  
if(breakWhile) JRB9rSN^  
break; LRL,m_gt  
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//count++; k>;`FFQU>  
//if(count>4) HiZ*+T.B  
// siteStop(); R!}H;[c  
} 6^]+[q}3  
!|^|,"A)  
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System.err.println("文件下载结束！"); 0XE4<U  
} eA2@Nkw~)  
catch(Exception e){e.printStackTrace ();} %)1y AdG 8  
} -|$@-
fY;  
bCRV\myd`  
,E S0NA  
//获得文件长度 C5o#i*|  
public long getFileSize() Y]'Z7<U}*E  
{ Bs^aII$  
int nFileLength = -1; *4\:8  
try{ ua3~iQj-  
URL url = new URL(siteInfoBean.getSSiteURL()); ]cHgleHQ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); +r2+X:#~T  
httpConnection.setRequestProperty("User-Agent","NetFox"); ]_f_w9]  
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int responseCode=httpConnection.getResponseCode(); Q /U2^  
if(responseCode>=400) P3x8UR=fS  
{ gb[5&>(#  
processErrorCode(responseCode); NcBIg:V\c  
return -2; //-2 represent access is error 9ijfRqI=x  
} 3lrT3a3vV  
11Q1AN  
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String sHeader; em%4Ap  
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for(int i=1;;i++) ?WGA?J %2  
{ %~4M+r6T  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); -_=nDH  
//Utility.log(in.readLine()); ,LHn90S  
sHeader=httpConnection.getHeaderFieldKey(i); j'Fpjt"&=  
if(sHeader!=null) <sb~ ^B  
{ }bb;~  
if(sHeader.equals("Content-Length"))  dm\F  
{ <}C oQz  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); |3(' N#|  
break; Vh|*p&  
} t%d Z-Ym  
} YL!P0o13r  
else (
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break; KI"#f$2&  
} `KZm0d{H  
} hNC&T`.-~B  
catch(IOException e){e.printStackTrace ();} 8
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catch(Exception e){e.printStackTrace ();} `'DmDg  
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Utility.log(nFileLength); ROH|PKb7  
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return nFileLength; HY56"LZ$(}  
} sA+ }TNhq  
(>LF(ll  
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//保存下载信息（文件指针位置） 1KU! tL  
private void write_nPos() )v'WWwXY>  
{ hZ|z|!g0  
try{ yl'u'-Zb6  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Ki;*u_4{  
output.writeInt(nStartPos.length); g_;\iqxL  
for(int i=0;i<nStartPos.length;i++) "BM#4  
{ )*u8/U  
// output.writeLong(nPos); `}p0VmD{NE  
output.writeLong(fileSplitterFetch.nStartPos); 7y.kQI?3  
output.writeLong(fileSplitterFetch.nEndPos); /T"+KU*
 
} mVj9,q0  
output.close(); * `JYC  
} 34f?6K1c  
catch(IOException e){e.printStackTrace ();} +Q/R{#O  
catch(Exception e){e.printStackTrace ();} =O~_Q-  
} 4S7v:1~xe  
J"0`%'*/  
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//读取保存的下载信息（文件指针位置） .#EFLXs  
private void read_nPos()  0HZ{Y9]  
{ 8'[~2/  
try{ (^ J
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); b!+hH Hv:  
int nCount = input.readInt(); -M\<nx  
nStartPos = new long[nCount]; 4j-Xi  
nEndPos = new long[nCount]; l5~os>  
for(int i=0;i<nStartPos.length;i++) d9k0F OR1  
{ ]a>n:p]e  
nStartPos = input.readLong(); 1a/++4O.|  
nEndPos = input.readLong(); EfqX y>W  
} N"Z{5A  
input.close(); 2IK}vDsis  
} pJ>P[  
catch(IOException e){e.printStackTrace ();} &j;wCvE4+  
catch(Exception e){e.printStackTrace ();} ez7A4>
/  
} Mc)}\{J  
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private void processErrorCode(int nErrorCode) b]e"1Y)D-  
{ &1Ok`_plO  
System.err.println("Error Code : " + nErrorCode); )j6~Wy@4  
} ]>!K3kB  
}H53~@WP>  
11NQR[  
//停止文件下载 9p]QM)M  
public void siteStop() HVRZ[Y<^  
{ wH*-(*N"  
bStop = true; 7 W5@TWM  
for(int i=0;i<nStartPos.length;i++) jVi) Efy  
fileSplitterFetch.splitterStop(); td$E/h=3  
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} \$K20)  
} 5%"V[lDx@  
//负责部分文件的抓取 ;[ZEDF5H  
**FileSplitterFetch.java Y_liA  
*/ xR~hwj  
package NetFox; e1yt9@k,  
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import java.io.*; O2V  
import java.net.*; !t"4!3  
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public class FileSplitterFetch extends Thread { aj='b.2)  
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String sURL; //File URL !
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long nStartPos; //File Snippet Start Position n9\TO9N  
long nEndPos; //File Snippet End Position G/E+L-N#`
 
int nThreadID; //Thread's ID }:zE< bK  
boolean bDownOver = false; //Downing is over p T?}Kc  
boolean bStop = false; //Stop identical hE{K=Tz$  
FileAccessI fileAccessI = null; //File Access interface <)Dj9' _J  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Q0sI(V#  
{ hgG9m[?K  
this.sURL = sURL; M-VX;/&FR  
this.nStartPos = nStart; r `=I  
this.nEndPos = nEnd; '@v\{ l  
nThreadID = id; @?sRj&w  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 E:68?IJ  
} gT.sjd  

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public void run() yX>K/68  
{ ,>a&"V^k  
while(nStartPos < nEndPos && !bStop) WCZjXDiwJ  
{ ^e,.  
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try{ u[;\y|75  
URL url = new URL(sURL); j^sg6.Z*  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (XTG8W sN  
httpConnection.setRequestProperty("User-Agent","NetFox"); k=$TGqQY?  
String sProperty = "bytes="+nStartPos+"-"; HQdxL*N%^  
httpConnection.setRequestProperty("RANGE",sProperty); FjH
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Utility.log(sProperty); z_$%-6  
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InputStream input = httpConnection.getInputStream(); RMV/&85?y  
//logResponseHead(httpConnection); 6yG^p]zZ  
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byte[] b = new byte[1024]; N{!i
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int nRead; 5{WE~8$  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) #lo6c;*m5  
{ KfEx"94  
nStartPos += fileAccessI.write(b,0,nRead); 0],r0  
//if(nThreadID == 1) NG=-NxEcN  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 5DU6rks%
 
} QO:!p5^:  
/{J4:N'B>  
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Utility.log("Thread " + nThreadID + " is over!"); n+9=1Oo"  
bDownOver = true; *8A  
//nPos = fileAccessI.write (b,0,nRead); C[AqFo  
} /U*C\ xMm  
catch(Exception e){e.printStackTrace ();} J1U/.`Oy  
} q[_VuA]&  
} oH?b}T=9jz  
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//打印回应的头信息 O/(`S<iip  
public void logResponseHead(HttpURLConnection con) }"H,h)T  
{ x8B}ZIbT9  
for(int i=1;;i++)  Mx?d  
{ net@j#}j-  
String header=con.getHeaderFieldKey(i);
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if(header!=null) Xu'&ynID  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 8FK/~,I  
Utility.log(header+" : "+con.getHeaderField(header)); <NY^M!  
else H2 {+)  
break; u~:y\/Y6  
} x_}:D *aI  
} Lg+Ac5y}`  
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public void splitterStop() ;8&3 dm]  
{ NiEUW.0  
bStop = true; RLXL&  
} ,-LwtePJ0  
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} >>
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/* |A~jsz6pI  
**FileAccess.java I_#kg
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*//文件访问(定位，写) eK=xrk  
package NetFox; 8 >EWKI
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import java.io.*; ah&D%8E  
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public class FileAccessI implements Serializable{ I*{nP)^9  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 LmrfN?5  
RandomAccessFile oSavedFile; myQagqRx  
long nPos; ~H_/zK6e  
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public FileAccessI() throws IOException Fnv;^}\z  
{ %N6A+5H  
this("",0); ~ 'cmSiz-  
} xh,qNnGGi  
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public FileAccessI(String sName,long nPos) throws IOException %@aS
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{ "Yv_B3p   
oSavedFile = new RandomAccessFile(sName,"rw"); .V/Rfq  
this.nPos = nPos; .G
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oSavedFile.seek(nPos); =[{i{x|Qz  
} Gr'  CtO  
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public synchronized int write(byte[] b,int nStart,int nLen) @f~RdO3  
{ 85$m[+md  
int n = -1; dr}`H,X"3  
try{ 6r0krbN  
oSavedFile.write(b,nStart,nLen); %D34/=(X  
n = nLen; KeB"D!={;  
} TDKki(o=~  
catch(IOException e) BLdvyVFx  
{ ItVWO:x&v  
e.printStackTrace (); %6,SKg p  
} PI
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return n; P>C~ i:4n  
} 29"'K.r  
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} ~9]hV7y5C  
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/* rig,mv  
**SiteInfoBean.java o Q2Fjj  
*/ `Bp.RXsd*  
package NetFox; *uf'zQ<9  
8 &LQzwa  
+b<FO+E_  
public class SiteInfoBean { $E~`\o%Ev  
A*2jENgci  
7M!I8C0!aO  
private String sSiteURL; //Site's URL cWaSn7p!X  
private String sFilePath; //Saved File's Path I\{ 1u  
private String sFileName; //Saved File's Name Y@vTaE^w3  
private int nSplitter; //Count of Splited Downloading File QzVnL U)  
W=><)miQ@  
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public SiteInfoBean() oy=js -  
{//nSplitter的缺省值为5 w^|*m/h|@u  
//default value of nSplitter is 5 ? 7n`A >T  
this("","","",5); =_2jK0+}l  
} ,t?B+$E  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 4N_R:B-Vu  
{ zuad~%D<I  
sSiteURL= sURL; 6+|do+0Icg  
sFilePath = sPath; ox~o J|@  
sFileName = sName; TH&U j1  
this.nSplitter = nSpiltter; _Xc8Yg }`  
:Zbg9`d*  
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} 2d #1=+V  
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public String getSSiteURL() @ $ ;q;  
{ 5|j<`()H :  
return sSiteURL; >}8j+t&T  
} Lv;^My  
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public void setSSiteURL(String value) X::JV7hu  
{ E)5\i-n  
sSiteURL = value; *20jz<  
} (AaoCa[  
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{yHCXFWlS  
public String getSFilePath() XK3tgaH  
{ O|{d[eX  
return sFilePath; F3@phu${  
} {OkV%Q<  
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.+3g*Dv{&  
public void setSFilePath(String value) ?W?c1>  
{ df4A RP+  
sFilePath = value; F2LLN  
} :Uzm  
M
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)9{0]u;9  
public String getSFileName() \^J%sf${  
{ d9fC<Tp  
return sFileName; XH4  
} %+W
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r1`x=r   
}(J}f)  
public void setSFileName(String value) ;;OAQ`  
{ eC
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sFileName = value; "Y =;.:qe  
} .PIL +x*]N  
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public int getNSplitter() s^G.]%iU  
{ 3=P]x;[ba  
return nSplitter; 6 6EV$*dRL  
} NqazpB*  
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public void setNSplitter(int nCount) D09Sg%w  
{ EPI4!3]  
nSplitter = nCount; #C74z$  
} T= y}y  
} ["k,QX  
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/* / |;RV"  
**Utility.java _lJ!R:*  
*/ mW(W\'~_~  
package NetFox; zx"s*:O
 
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public class Utility { Olt?~}  
#?U}&Bd  
,*TmIPNK  
public Utility() M>xK+q?O  
{ B:yGS*.tu  
;s= l52  
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} Q2w_X8  
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//线程睡眠 5,lEx1{_  
public static void sleep(int nSecond) hP%M?MKC  
{ y{B=-\O]  
try{ a8e6H30Sm  
Thread.sleep(nSecond); T9E+\D  
} Tj`,Z5vy  
catch(Exception e) "yy5F>0Wt  
{ >-RQ]?^  
e.printStackTrace (); ~OYiq}g  
} x*\Y)9Vgy  
} }#RakV4  
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//日志 %8B}Cb&2c  
public static void log(String sMsg) A7Cm5>Y_S  
{ kYP#SH/  
System.err.println(sMsg); Ytp(aE:  
} #1A.?p  
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R6<X%*&%  
public static void log(int sMsg) }z'8Bu  
{ j;+b0(53  
System.err.println(sMsg); $l
fn(b,  
} 6m/r+?'  
} U/66L+1  
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J\}
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/* hE'-is@7  
**TestMethod.java 4$HhP,gL=  
*/ ) yi E@ X  
package NetFox; <Uk}o8E  
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kr^P6}'  
public class TestMethod { q5J5>  
Gt8M&S-;  
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public TestMethod() |#v7/$!  
{ ///xx/weblogic60b2_win.exe u"r`3P`  
try{ D#9m\o_  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); G/y5H;<9M  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ihhDOmUto  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ^&9zw\x;z  
fileFetch.start(); ;0]aq0_#(  
} xk9%F?)
 
catch(Exception e){e.printStackTrace ();} IEL%!RFG  
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} .Bl\Z  
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public static void main(String[] args) y;m|  
{ i<C*j4qQ  
new TestMethod(); nK1Slg#U  
} >mbHy<<  
} 9d0@wq.  
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