http断点续传简单实现（java)

/* oIxH3T  
**SiteFileFetch.java 7P*Z0%
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*/ rJV?)=Z  
package NetFox; s0lYj@E'  
import java.io.*; fnOIv#  
import java.net.*; PpFsp( )x  
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public class SiteFileFetch extends Thread { 1Z 6SI>p  
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SiteInfoBean siteInfoBean = null; //文件信息Bean VDa|U9N  
long[] nStartPos; //开始位置 |D<+X^0'  
long[] nEndPos; //结束位置 S&01SX6  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 jsZY{s=  
long nFileLength; //文件长度 ` FxtLG,F  
boolean bFirst = true; //是否第一次取文件 U`1l8'W}:#  
boolean bStop = false; //停止标志 4+Ti7p06&\  
File tmpFile; //文件下载的临时信息 F.0d4:A+  
DataOutputStream output; //输出到文件的输出流 VVLIeJ(*XT  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） N7pt:G2~%  
public SiteFileFetch(SiteInfoBean bean) throws IOException ?K<ZkYw?  
{ _+n;A46  
siteInfoBean = bean; w[sR7T9*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); [Xh\mDU.  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); pYh!]0n  
if(tmpFile.exists ()) $T/#1w P  
{ = t-fYV  
bFirst = false; PCZ]R  
read_nPos(); $?$9y^\  
} pL)xqKj  
else O9*p0%ug  
{ 6(.H3bu
 
nStartPos = new long[bean.getNSplitter()]; 1J'pB;.]s  
nEndPos = new long[bean.getNSplitter()]; +c r  
} &57U? oY  
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} R9vY:oN%  
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public void run() O#G| ~'.,  
{ lR}%)3_k  
//获得文件长度 _>i|s|aW  
//分割文件 QT;Va#a  
//实例FileSplitterFetch 1LyT7h  
//启动FileSplitterFetch线程 k9&@(G[K3  
//等待子线程返回 )UP8#|$#T  
try{ MHl^/e@  
if(bFirst) eE9|F/-L  
{ CO'a
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nFileLength = getFileSize(); -5xCQJ[  
if(nFileLength == -1) 17i$8  
{ /x/4NeD  
System.err.println("File Length is not known!"); ((cb4IX  
} 6Hn)pD#U  
else if(nFileLength == -2) m#MlH=-  
{ P}l#VJWp  
System.err.println("File is not access!"); _uJV
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}
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else ZOn_dYjC  
{ phS>T  
for(int i=0;i<nStartPos.length;i++) 3SFg#  
{ @?d?e+B  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); LfllO  
} (Y)!"_|  
for(int i=0;i<nEndPos.length-1;i++) xx0k$Dqt2I  
{ |!xpYT:  
nEndPos = nStartPos[i+1]; `oVB!eapl  
} Rn;VP:HM  
nEndPos[nEndPos.length-1] = nFileLength;
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} RJ*F>2  
} f8#*mQ  
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//启动子线程 O4N-_Kfp/  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; o$\tHzB9!A  
for(int i=0;i<nStartPos.length;i++) t\|J&4!Y  
{ hb<k]-'!  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Pxk0(oBX  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), *`1bc'umM;  
nStartPos,nEndPos,i); S\b K+  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); niQcvnT4b  
fileSplitterFetch.start(); #]X2^ND47  
} %Zu
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ZMe}M!V  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); \=Nm5:  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $W*|~}F/Ap  
nEndPos = " + nFileLength); F"v:}Vy|   
// fileSplitterFetch[nPos.length-1].start(); `[bJYZBc2  
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//等待子线程结束 c>rKgx  
//int count = 0; {=6)SBjf  
//是否结束while循环 2!idy]vy_  
boolean breakWhile = false; P>fKX2eQ-  
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while(!bStop) Y-= /,   
{ -~} tq]  
write_nPos(); :t%)5:@A  
Utility.sleep(500); dEG ]riO  
breakWhile = true; S?2YJl8B  
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for(int i=0;i<nStartPos.length;i++) E#a
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{ =R2l3-HA=  
if(!fileSplitterFetch.bDownOver) DU`v J2  
{ !h*B (,  
breakWhile = false; *73AAA5LKa  
break; qy6K,/&3  
} 0:#7M}U  
} ^X^,>Z|  
if(breakWhile) `yx56  
break; A9iQ{l  
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//count++; )\"I*Jwir  
//if(count>4) %b9fW  
// siteStop(); A'`P2Am  
} &8afl"_~  
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System.err.println("文件下载结束！"); q}e]*]dJZ  
}  +xq=<jy  
catch(Exception e){e.printStackTrace ();} BJ2Q2WW  
} d{3I.$ThH  
^9s"FdB]24  
~Zu}M>-^c,  
//获得文件长度 Z>&K&ttJ  
public long getFileSize() 97(n\Wt2  
{ 3r`<(%\  
int nFileLength = -1; {>A
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try{ SKW;MVC  
URL url = new URL(siteInfoBean.getSSiteURL()); {<r`5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); GeVc\$K-  
httpConnection.setRequestProperty("User-Agent","NetFox"); @~hz_Nm@8  
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int responseCode=httpConnection.getResponseCode(); 7G2vYKC'  
if(responseCode>=400) 38"cbHE3  
{ egbb1+tY  
processErrorCode(responseCode); OFQ{9  
return -2; //-2 represent access is error "!^c  
} 'cYQ?;  
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String sHeader; _Po#ZGm~  
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for(int i=1;;i++) "s${!A)  
{ Ir^BC!<2>  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); r.9 $y/5  
//Utility.log(in.readLine()); 8>m1UONr  
sHeader=httpConnection.getHeaderFieldKey(i); dw3'T4TC?  
if(sHeader!=null) bYK]G+Ww  
{ D?%e"*>  
if(sHeader.equals("Content-Length")) kv/(rKLp*  
{ LK{a9` h  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); uFWvtL?;_  
break; 5"[yFmP*  
} VSx%8IM+X  
} FGDw;lEa9[  
else BJ"Ay@D*  
break; ;*_I,|A:Xr  
} 9wzg{4/-$  
} wqf&i^_  
catch(IOException e){e.printStackTrace ();} tG_-;03<`4  
catch(Exception e){e.printStackTrace ();} FR
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Utility.log(nFileLength); +B](5z4  
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return nFileLength; xTGP  
} cK/PQs
MP  
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+A&EKk%$ |  
//保存下载信息（文件指针位置） [GOX0}$?  
private void write_nPos() O3!Ouh&  
{ zo/0b/lQ  
try{ ocq2  
output = new DataOutputStream(new FileOutputStream(tmpFile)); G[vUOEU~O  
output.writeInt(nStartPos.length); \l>qY(gu  
for(int i=0;i<nStartPos.length;i++) Ja^7$WY
 
{ -aC!0O y`  
// output.writeLong(nPos); ^Kb9@lz/  
output.writeLong(fileSplitterFetch.nStartPos); #*[,woNk  
output.writeLong(fileSplitterFetch.nEndPos); EUJ1RhajF  
} 'M47'{7
T  
output.close(); vR<fdV  
} XryQ)x(  
catch(IOException e){e.printStackTrace ();} m9v"v:Pw  
catch(Exception e){e.printStackTrace ();} e=0l<Rj  
} lR|$*:+  
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//读取保存的下载信息（文件指针位置） k];L!Fj1  
private void read_nPos() D>psh-,1  
{ rE!G,^_{  
try{ V]+o)A
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Kc%tnVyGh:  
int nCount = input.readInt(); Nck!z8  
nStartPos = new long[nCount]; |`N$>9qN  
nEndPos = new long[nCount]; eTLI/?|+N  
for(int i=0;i<nStartPos.length;i++) L#83f]vG  
{ e);bF>.~  
nStartPos = input.readLong(); B]&Lh~Im  
nEndPos = input.readLong(); -='8_B/75  
} tf.q~@Pi  
input.close(); aNuZ/9O  
} 
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catch(IOException e){e.printStackTrace ();} <=B1"'\  
catch(Exception e){e.printStackTrace ();} 6,CU)-98G  
} zav*  
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private void processErrorCode(int nErrorCode) 1]a*Oer}  
{ LAu+{'O\  
System.err.println("Error Code : " + nErrorCode); b/a?\0^  
} 6E)uu; 8  
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//停止文件下载 [R@q]S/  
public void siteStop() x= vE&9_u  
{ ,qBnqi[  
bStop = true; jSUAU}u!M  
for(int i=0;i<nStartPos.length;i++) '91u q  
fileSplitterFetch.splitterStop(); FJ3:}r6 "  
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} Bd N{[2  
} ZmYa.4'L  
//负责部分文件的抓取 4iL.4Uj{N  
**FileSplitterFetch.java ~T;ajvJ  
*/ P?WT)C2)u  
package NetFox; $=@9 D,R  
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import java.io.*; ]$XBd{\D{  
import java.net.*; T_YMM'`  
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public class FileSplitterFetch extends Thread { &VZmP5Gv  
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String sURL; //File URL cLN[o8ZU  
long nStartPos; //File Snippet Start Position ],fwZd[t  
long nEndPos; //File Snippet End Position rH#c:BwSm  
int nThreadID; //Thread's ID P?3YHa^up  
boolean bDownOver = false; //Downing is over qxecp2>U  
boolean bStop = false; //Stop identical h~=\/vF  
FileAccessI fileAccessI = null; //File Access interface UG^?a  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Y9
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{ 709Uv5  
this.sURL = sURL; sg9x?Bx9  
this.nStartPos = nStart; yv#c=v|  
this.nEndPos = nEnd; X&FuqB  
nThreadID = id; ]y)R
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 Ilt L@]e  
} ^V0{Ew/x  
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public void run() k_|v)\4B  
{ B1i!te}*  
while(nStartPos < nEndPos && !bStop) J!TK*\a2  
{ M#8Ao4 T  
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try{ hAxuZb7 ?  
URL url = new URL(sURL); #G4~]Qml  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 
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httpConnection.setRequestProperty("User-Agent","NetFox"); bTy'5"  
String sProperty = "bytes="+nStartPos+"-"; D0E"YEo\nv  
httpConnection.setRequestProperty("RANGE",sProperty); 6UzT]"LR;  
Utility.log(sProperty); j O5:{%  
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InputStream input = httpConnection.getInputStream(); n[cyK$"  
//logResponseHead(httpConnection); #&`WMLl+8  
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byte[] b = new byte[1024]; ;P0Y6v3  
int nRead; ?/|@ #&  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) dnWt\>6& 2  
{ *l'$pJ X  
nStartPos += fileAccessI.write(b,0,nRead); /cg]wG!n8  
//if(nThreadID == 1) $et :  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); GYb2m"a)  
} (=3&8$  
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Utility.log("Thread " + nThreadID + " is over!"); NE>JtTF<  
bDownOver = true; KHs{/  
//nPos = fileAccessI.write (b,0,nRead); Mbi+Vv-  
} x#e\H F  
catch(Exception e){e.printStackTrace ();} rEpKX  
}
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} pil*/&pB  
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//打印回应的头信息 Gp3t?7S{T  
public void logResponseHead(HttpURLConnection con) %_J/&{6G  
{ YT%SCaU  
for(int i=1;;i++) \$\(
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{ l<MCmKuYp  
String header=con.getHeaderFieldKey(i); hb8@br  
if(header!=null) K&P{2Hndr  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); *~oDP@[S  
Utility.log(header+" : "+con.getHeaderField(header)); -Fw4;&>  
else O@(.ei*HJ!  
break; }${ZI  
} ALt";8Oa  
} ~\s &]L  
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public void splitterStop() wb Tg  
{ y7G|P~td  
bStop = true; <x;[ H%  
} 5J2p^$s  
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} @_(@s*4W  
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/* pS)X\Xyw  
**FileAccess.java )mZy>45  
*//文件访问(定位，写) *CD=cmdD*  
package NetFox; h|>n3-k|p  
import java.io.*; jnLu|W&  
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public class FileAccessI implements Serializable{ McI4oD~"  
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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 qmeEUch`  
RandomAccessFile oSavedFile; 21
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long nPos; xupdjT%4  
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public FileAccessI() throws IOException Vm8_ !$F  
{ <YNPhu~5  
this("",0); o;-!?uJ  
} e&7}N Za
 
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public FileAccessI(String sName,long nPos) throws IOException (#Kvm  
{ %_LHD|<  
oSavedFile = new RandomAccessFile(sName,"rw"); DG9;6"HBX  
this.nPos = nPos; 0<Y&2<v  
oSavedFile.seek(nPos); ?#y<^oNM  
} rG%_O$_dO  
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public synchronized int write(byte[] b,int nStart,int nLen) CxN@g'  
{ rpI7W?hh  
int n = -1; 2Yf;b9-k  
try{ %+JTQy  
oSavedFile.write(b,nStart,nLen); EHM 7=|#  
n = nLen; 2Rp{]s$jo  
} M@86u^80  
catch(IOException e) yBjWPx?  
{ !7kOw65+0  
e.printStackTrace (); *)SgdC/f  
} n>+W]I&E  
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return n; sbhEZ#7#  
} ^/YAokj  
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} `d;izQ1_=  
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bg. KkJMrR  
/* {v'Fg  
**SiteInfoBean.java /[T8/7;_l  
*/ TBp5xz`  
package NetFox; #gT^hl5/  
j[eEyCW[)  
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public class SiteInfoBean { 5Rp2O4Z  
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6$.Xj\zl  
private String sSiteURL; //Site's URL };sm8P
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private String sFilePath; //Saved File's Path ~"B[6^sW  
private String sFileName; //Saved File's Name s*WfRY*=V  
private int nSplitter; //Count of Splited Downloading File /T(~T  

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public SiteInfoBean() IbQ~f+y&2  
{//nSplitter的缺省值为5 Q1B!W  
//default value of nSplitter is 5 |0%UM}  
this("","","",5); Jxp'.oo[  
} !XC7FUO  
73`UTXvWU  
n
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) d)sl)qt}0  
{ ;VBfzFH  
sSiteURL= sURL; ^}L$[P  
sFilePath = sPath; 5ZxBmQ  
sFileName = sName; )gF9D1eA  
this.nSplitter = nSpiltter; %Qb
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} =w>QG{-N  
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public String getSSiteURL() )Ggx  
{ gJ7puN  
return sSiteURL; L+CSF ]  
} )HE yTHLtJ  
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public void setSSiteURL(String value) ?g.w%Mf*  
{ B!anY}/U  
sSiteURL = value; n|6yz[N  
} K.7gd1I  
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public String getSFilePath() pn|{P<b\  
{ "de:plMofy  
return sFilePath; HOG7||&y  
} O}V2>W$  
\O~P !`  
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public void setSFilePath(String value) G_]mNh  
{ p(>'4#|qy  
sFilePath = value; ^j7pF.j  
} ~Sq >c3Wn  
DK1)9<  
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public String getSFileName() CcQ|0  
{ hSH-Ck@Qy  
return sFileName; 'fsOKx4Z  
} ".4^?d_^VF  
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public void setSFileName(String value) {n'}S(  
{ bE"CSK#  
sFileName = value; uzD{ewR/.y  
} Mt`.|N;y!  
b"b!&u
 
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public int getNSplitter() ;7hr8?M|  
{ $Izk]o;X~  
return nSplitter; _De;SB%V  
} hZy*E[i  
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public void setNSplitter(int nCount) WYL.J5O  
{ 3#unh`3b  
nSplitter = nCount; =Ju}{ bX  
} \D=B-dREq  
} vvCGzOv  
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/* b3H;Ea?^^<  
**Utility.java DS yE   
*/ \b->AXe8  
package NetFox; Y/gCtSF  
4M}/PoJ  
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public class Utility { zF
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public Utility() !=pemLvH  
{ Zh$Z$85p  
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} 2bmppDk  
_4+1c5Q!  
//线程睡眠 9]iDNa/D  
public static void sleep(int nSecond) ,7aqrg  
{ 5VfP@{  
try{ i2DR}%U  
Thread.sleep(nSecond); )? xg=o/?  
} I g`#U~  
catch(Exception e) FB""^IC?W  
{ G>j/d7  
e.printStackTrace (); f 36rU  
} d hy=x  
} +;T%7j"wz  
Z:}^fZP  
//日志 RN0Rk 8AC  
public static void log(String sMsg) ?d 4_'y   
{ YA jk'  
System.err.println(sMsg); PNq#o%q  
} lc^%:#@  
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public static void log(int sMsg) w[XW>4xK  
{ !**q20-aP  
System.err.println(sMsg); :}lE@Y,R   
} u4Sa4o  
} T!n<ya
!  
;8!D8o(+  
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/* ;iEqa"gO  
**TestMethod.java E_? M&  
*/ <]<50  
package NetFox; _+U`afV  
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public class TestMethod { U!h!z`RU54  
5g=" #  
],LOkAX  
public TestMethod() 2:]Sy4K{  
{ ///xx/weblogic60b2_win.exe 0o#lB^e;l  
try{ 5v]x
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ^m~=<4eX  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); C]k\GlhB  
SiteFileFetch fileFetch = new SiteFileFetch(bean); [4gv_g  
fileFetch.start(); Gf
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} |D\ ukml  
catch(Exception e){e.printStackTrace ();} ,?}TSJKC  
:c\NBKHv*  
',.Xn`c  
} `bi5#xR  
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)}EwEM  
public static void main(String[] args) |1neCP@ng  
{ E^rN)  
new TestMethod(); zw0p}  
} ka(xU#;  
} 3cnsJV]  
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