http断点续传简单实现（java)

/* pgiZA?r*<  
**SiteFileFetch.java L+p}%!g  
*/ U,Uy0s2r  
package NetFox; od5nRb  
import java.io.*; `2LmLFkb  
import java.net.*; 2G$px  
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public class SiteFileFetch extends Thread { TfT^.p*  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ZOcpF1y  
long[] nStartPos; //开始位置 m_CWVw  
long[] nEndPos; //结束位置 ?bt;i>O\  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 88,hza`#V  
long nFileLength; //文件长度 Hg<aU*o;  
boolean bFirst = true; //是否第一次取文件 7)5G 1  
boolean bStop = false; //停止标志 _h5d~  
File tmpFile; //文件下载的临时信息 w8R7Ksn(  
DataOutputStream output; //输出到文件的输出流 gd]S;<Jh  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） o$l8"Uv  
public SiteFileFetch(SiteInfoBean bean) throws IOException =0
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{ y6tqemz  
siteInfoBean = bean; yP"}(!~m
 
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); |;xEKnF  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); JbL3/h]  
if(tmpFile.exists ()) Dy,MQIM|!  
{ v%AepK&  
bFirst = false;  YTZ :D/  
read_nPos(); Zi+FIQ(  
} Gf3-%s xA  
else :wXiz`VH  
{ #::+# G  
nStartPos = new long[bean.getNSplitter()]; 6H: f
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nEndPos = new long[bean.getNSplitter()]; ,b -  
} Anu:  
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} ar\|D\0V  
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public void run() p+|8(w9A${  
{ Z!~_#_Ugl  
//获得文件长度 {6h 1  
//分割文件 ^h2+""  
//实例FileSplitterFetch 3^%2,  
//启动FileSplitterFetch线程 ,7bhUE/VB  
//等待子线程返回 %L-qAI&V  
try{ /CO=!*7fz  
if(bFirst) L&)e}"  
{ aVK,(j9u  
nFileLength = getFileSize(); mj e9i  
if(nFileLength == -1) s|A[HQUtJ  
{ e+-#/i*  
System.err.println("File Length is not known!"); 6q8}8;STTY  
} AVw oOvJ  
else if(nFileLength == -2) i0/QfB%O  
{ b way+lh  
System.err.println("File is not access!"); @@U  
} >AX_"Q~  
else ZCj1Cz]"l<  
{ SyI~iW#Y1  
for(int i=0;i<nStartPos.length;i++) Qt{){u
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{ iTq&h=
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); tt2 S.j  
} 9ghzK?Yc  
for(int i=0;i<nEndPos.length-1;i++) X"d"a={]  
{ y3b"'-%  
nEndPos = nStartPos[i+1]; m4oj1h_4  
} tmq?h%O>  
nEndPos[nEndPos.length-1] = nFileLength; }:c~5whN  
} 4V
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} B-w`mcqp$  
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//启动子线程 _,60pr3D'  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; xBc|rqge  
for(int i=0;i<nStartPos.length;i++) -O?HfQ  
{ CF','gPnc  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), BK4S$B  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), d3q.i5']G  
nStartPos,nEndPos,i); Qd YYWD   
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); u28$V]
 
fileSplitterFetch.start(); \3^V-/SJf  
} h M7 SGEV  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 9#P~cW?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); i"iy 0?  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", K/Yeh<_&  
nEndPos = " + nFileLength); ![ce }  
// fileSplitterFetch[nPos.length-1].start(); R|8L'H+1x  
467"pqT  
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//等待子线程结束 )#M$ov  
//int count = 0; )#i"
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//是否结束while循环 %i3[x.M  
boolean breakWhile = false; %.f%Q?P  
|wv+g0]Pg^  
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while(!bStop) PVF:p7  
{ %G2g @2  
write_nPos(); W`vPf  
Utility.sleep(500); ysG1{NOl  
breakWhile = true; <";1[A%7<  
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for(int i=0;i<nStartPos.length;i++) ibZ[U p?  
{ \8<[P(!3  
if(!fileSplitterFetch.bDownOver) Gr&e]M[l  
{ N".BC|r  
breakWhile = false; UW8yu.`?  
break; 7Ko*`-p  
} P.q7rk<  
} +JC"@  
if(breakWhile) '@+q_v@Jl  
break; Ew{*)r)m  
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//count++; BNjMq  
//if(count>4) H.XyNtJ  
// siteStop(); <)a$5"AP  
} OqMdm~4B!j  
/KC^x=Xv:  
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System.err.println("文件下载结束！"); s?m_zJh  
} FO[ s;dmzu  
catch(Exception e){e.printStackTrace ();} 4Ol1T(J#  
} Hs8JJGXWB  
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//获得文件长度 =J)-#|eZG  
public long getFileSize() SC%HHu\l  
{ h
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int nFileLength = -1; /~WBqcl  
try{ !9HWx_,|Z  
URL url = new URL(siteInfoBean.getSSiteURL()); oXht$Q  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~Azj 
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httpConnection.setRequestProperty("User-Agent","NetFox"); 9v;[T%%  
*a\x!c"  
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int responseCode=httpConnection.getResponseCode(); G)NqIur*Z  
if(responseCode>=400) 6p&2A  
{ (z)#}TC  
processErrorCode(responseCode); V*O[8s%5v  
return -2; //-2 represent access is error H1q,w|O9j  
} ;:oJFI#;  
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String sHeader; .p=J_%K}0x  
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for(int i=1;;i++) lY@2$q9BT  
{ `5oXf  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 2i#Ekon  
//Utility.log(in.readLine()); ?o6#i3k#'  
sHeader=httpConnection.getHeaderFieldKey(i); eB9&HD:  
if(sHeader!=null) zBq&/?  
{ A7#nBHwxZ  
if(sHeader.equals("Content-Length")) Y=Ic<WHR  
{ ^fO9oPM|  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); KwaxNb5  
break; T zS?WYF  
} ,d lq2  
} 0/|Ax-dK  
else sl@>
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break; 4HZXv
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} 2#yDVN$  
} N$t<&5+  
catch(IOException e){e.printStackTrace ();} pN9U1!|uam  
catch(Exception e){e.printStackTrace ();} LcA7f'GVK  
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Utility.log(nFileLength); #b)
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return nFileLength; %ueD3;V  
} }.8yKj^p  
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//保存下载信息（文件指针位置） kzK9.  
private void write_nPos() x%ccNP0  
{ KrG,T5  
try{ NhTJB7  
output = new DataOutputStream(new FileOutputStream(tmpFile)); >iG3!Td)y  
output.writeInt(nStartPos.length); HrZX~JnTmf  
for(int i=0;i<nStartPos.length;i++) :|ahu  
{ 6XCFL-o-  
// output.writeLong(nPos); B:UM2Jl   
output.writeLong(fileSplitterFetch.nStartPos); KlS#f  
output.writeLong(fileSplitterFetch.nEndPos); "Vl4=W)u  
} :Sd`4
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output.close(); sz/^Ie-~  
} cl4_M{~  
catch(IOException e){e.printStackTrace ();} (`#z@
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catch(Exception e){e.printStackTrace ();} r: >RH,  
} mqsAYzG  
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//读取保存的下载信息（文件指针位置） !"RRw&0M  
private void read_nPos() -(lP8Y~gFY  
{ kmu`sk"  
try{ 9I<~t@q5e@  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); }!Pty25j  
int nCount = input.readInt(); umnQ$y 0  
nStartPos = new long[nCount]; +rSU  
nEndPos = new long[nCount]; CSW+UaE  
for(int i=0;i<nStartPos.length;i++) Gl|n}wo$  
{ z>y#^f)r  
nStartPos = input.readLong(); #l- 0$  
nEndPos = input.readLong(); q o^mp  
} S#yGqN0i  
input.close(); a%kvC#B  
} ,g0t&jITo  
catch(IOException e){e.printStackTrace ();} Np$&8v+en  
catch(Exception e){e.printStackTrace ();} o-l-Z|)7  
} D{y7[#$h$  
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private void processErrorCode(int nErrorCode) yVXVHCB  
{ ?fC9)s  
System.err.println("Error Code : " + nErrorCode); d8 Jf3Mo  
} Wuk8&P3  
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//停止文件下载 U~?mW,iRL  
public void siteStop() 6=,zkU*i^  
{ -$g~,dIwj  
bStop = true; #6D>e~>n  
for(int i=0;i<nStartPos.length;i++) 9v-Y*\!w.  
fileSplitterFetch.splitterStop(); /~;!Ew|q  
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} O(=9&PRi  
} #QcRN?s  
//负责部分文件的抓取 rMjb,2*rC7  
**FileSplitterFetch.java MXEI/mDYK  
*/ T=sAy/1oR  
package NetFox; `T1bY9O.  
1HAnOy0   
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import java.io.*; 0QfDgDX  
import java.net.*; C$C>RYE?.  
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public class FileSplitterFetch extends Thread { _&s pMf  
8qw{e`c  
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String sURL; //File URL olxxs(  
long nStartPos; //File Snippet Start Position ln8N
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long nEndPos; //File Snippet End Position /2/aMF(J  
int nThreadID; //Thread's ID 5=#d#dDc  
boolean bDownOver = false; //Downing is over emrA!<w!W  
boolean bStop = false; //Stop identical OA\]|2 :  
FileAccessI fileAccessI = null; //File Access interface VMJaL}J]  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException OUGkam0UK  
{ ;]>)6  
this.sURL = sURL; }KIS_krs  
this.nStartPos = nStart; ,tyPZR_  
this.nEndPos = nEnd; C%]qK(9vvd  
nThreadID = id; #s\kF *  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 SRk!HuXh  
} @0t[7Nv-1  
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public void run() @b^$h:H  
{ lic-68T  
while(nStartPos < nEndPos && !bStop) HOPy&Fp  
{ Nz`v+sp  
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try{ ceCO*m~  
URL url = new URL(sURL); qS!N\p~>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Pz:,de~5Qm  
httpConnection.setRequestProperty("User-Agent","NetFox"); =VZ_';b h  
String sProperty = "bytes="+nStartPos+"-"; e?+-~]0  
httpConnection.setRequestProperty("RANGE",sProperty); m$v >r\*X  
Utility.log(sProperty); @sg.0GR  
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InputStream input = httpConnection.getInputStream(); aL+>XN  
//logResponseHead(httpConnection); 5*YvgB;  
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byte[] b = new byte[1024]; Y(kf<Wo  
int nRead; >.K%W*t  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) P\6:euI  
{ iZeq l1O  
nStartPos += fileAccessI.write(b,0,nRead); W,CAg7:*  
//if(nThreadID == 1) #\D74$D  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [Eu)~J*
 
} ZOa|lB (,  
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Utility.log("Thread " + nThreadID + " is over!"); 6XU p$Pd(  
bDownOver = true; BU??}{  
//nPos = fileAccessI.write (b,0,nRead); Gs3V]qbEP  
} 6G"UXNa,  
catch(Exception e){e.printStackTrace ();} h| wdx(4  
} ?#Z4Dg 9|  
} \ ya@9OA  
|#Lz0<c;  
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//打印回应的头信息 g9VY{[V  
public void logResponseHead(HttpURLConnection con) g\.$4N  
{ ,3f>-mP  
for(int i=1;;i++) ku]?"{Xx  
{ `<>QKpAn  
String header=con.getHeaderFieldKey(i); kI@<H<  
if(header!=null) IHd W!q  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); "P(obk  
Utility.log(header+" : "+con.getHeaderField(header)); $rr@3H+  
else v)_FiY QQ6  
break; ?(d1;/0v>  
} N AY3.e  
} u?dPCgs;h  
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public void splitterStop() 3Z*o5@RI  
{ AL3iNkEa  
bStop = true; J9]cs?`)  
} <a
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} Bh cp=#  
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/* z rSPa\M  
**FileAccess.java I%a-5f$0  
*//文件访问(定位，写) AzXLlQ  
package NetFox; ]2)A/fOW  
import java.io.*; j"h/v7~  
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public class FileAccessI implements Serializable{ lbIPtu  
XJ3sqcS  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 7G-?^  
RandomAccessFile oSavedFile; `{Q'iydU  
long nPos; bK~Toz<k  
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public FileAccessI() throws IOException !vRZh('R  
{ b-  t  
this("",0); f?k0(rl  
} h L [eA  
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public FileAccessI(String sName,long nPos) throws IOException vZTXvdF  
{ ^-k"gLg  
oSavedFile = new RandomAccessFile(sName,"rw"); Po@;PR=  
this.nPos = nPos; =r ^_D=  
oSavedFile.seek(nPos); |R@T`dW  
} U[?_|=~7  
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public synchronized int write(byte[] b,int nStart,int nLen) *1`X}  
{ b1 w@toc  
int n = -1; 1s=Q~*f~d  
try{ G)}[!'<rR  
oSavedFile.write(b,nStart,nLen); jD9u(qAlH  
n = nLen; Y&O2;q/B  
} &U]/SFY  
catch(IOException e) <O'U-. Gc  
{ >rEZ$h  
e.printStackTrace (); C){Q;`M-<  
} ySO\9#Ho  
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;
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return n; (wZ!OLY%}  
} qovsM
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} l|gi2~ %Y  
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/* \M\7k5$  
**SiteInfoBean.java klm>/MXI`  
*/ >bZ-mX)j\0  
package NetFox; Ei
@  
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public class SiteInfoBean { TxG@#" ^g}  
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private String sSiteURL; //Site's URL !X-\;3kC0  
private String sFilePath; //Saved File's Path C'$}{%Cc@$  
private String sFileName; //Saved File's Name 'A:Y&w"r  
private int nSplitter; //Count of Splited Downloading File kMch   
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2\1+M)  
public SiteInfoBean() I{(!h90  
{//nSplitter的缺省值为5 lgU!D |v  
//default value of nSplitter is 5 BVb^xL  
this("","","",5); LsERcjwwK  
} }UW*[dCf>C  
?{f6su@rW  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Wds>'zzS  
{ c 1F^Gj!8  
sSiteURL= sURL; K& ^qn&  
sFilePath = sPath; X#$ oV#  
sFileName = sName; +-|""`I1I  
this.nSplitter = nSpiltter; ,#ZPg_x?1  
9#:nlu9  
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} ?Cf'IBpN  
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public String getSSiteURL() .-rz30xT  
{ N+c|0  
return sSiteURL; La1:WYt  
} n&;JW6VQS  
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; D
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public void setSSiteURL(String value) [#gm[@d,  
{ ?l6yLn5si^  
sSiteURL = value; .euAN8L  
} @9 S ::  
/8qR7Z^HZ  
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public String getSFilePath() Z.gb'  
{ EWDsBNZaI  
return sFilePath; PM[W7gT  
} j? BL8E'   
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public void setSFilePath(String value) g3
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{ Gpxp8[ {  
sFilePath = value; U!|)M  
} lot`6]  
@ ,X/Wf  
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public String getSFileName() wd*B3  
{ jV*10kM<  
return sFileName; [IOI&`?D  
} y{mt *VA4  
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public void setSFileName(String value) tjtvO@?1-  
{ np^&cY]  
sFileName = value; b_ZvI\H  
} a.%ps:  
6NV592  
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public int getNSplitter() G]aey>)  
{ 30^q_|l:]  
return nSplitter; O.Pp*sQ^  
} ++,I`x+p  
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public void setNSplitter(int nCount) q("XS  
{ g$GGo[_0  
nSplitter = nCount; :} =lE"2  
} [x{$f7CEh  
} SV t~pE+Y  
3#,6(k4>  
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/* Cty{  
**Utility.java *Ze0V9$'  
*/ )KFxtM-  
package NetFox; ||X3g"2W9  
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s*gqKQ;  
public class Utility { HQ"T>xb  
'm*
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public Utility() e+BZoK ^  
{ ZOPK  
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} A!!!7tj  

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//线程睡眠 3mU~G}ig  
public static void sleep(int nSecond) hev;M)t  
{ $rW(*#C  
try{ k ?KJ8  
Thread.sleep(nSecond); ( xooU 8d  
} X9?)P5h=  
catch(Exception e) MUl7o@{'  
{ e]1'D  
e.printStackTrace (); 0^>,  
} H
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} &mtt,]6C_  
npzp/mcIe)  
//日志 xDw~n(*  
public static void log(String sMsg) m BvO<?ec  
{ (^i
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System.err.println(sMsg); [r"Oi| 8I  
} 3\}u#/Vb  
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7Q|<6210  
public static void log(int sMsg) :8OT  
{ 8:
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System.err.println(sMsg); vzs4tkG  
} ]CLM'$  
} DQK?y=vf  
rtAPkXJFM  
>(P(!^[f  
/* 5B)&;[  
**TestMethod.java
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*/ G8vDy1`q6  
package NetFox; G 3U[)("  
X[Ufq^fyA  
/v9qrZ$$  
public class TestMethod { R/"f  
g(i6Uj~)  
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public TestMethod() !D['}%
 
{ ///xx/weblogic60b2_win.exe #%QHb,lhl  
try{ G?@W;o)  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); MuMq%uDA"  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); `l'T/F\  
SiteFileFetch fileFetch = new SiteFileFetch(bean); `PAQv+EYz  
fileFetch.start(); jC[
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} !dwZ`D  
catch(Exception e){e.printStackTrace ();} (rhlK} C  
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} plPPf+\  
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public static void main(String[] args) S||W  
{ EGgw#JAi#t  
new TestMethod(); '6vo#D9M  
} kCEuzd=$V  
} ) ??N]V_U  
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