http断点续传简单实现（java)

/* QW@`4W0F  
**SiteFileFetch.java 1QuR7p  
*/ v|r#  
package NetFox; klC48l  
import java.io.*; +Xr87x;  
import java.net.*; UazUr=|e  
<Dp[F|r  
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public class SiteFileFetch extends Thread { bcprhb  

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SiteInfoBean siteInfoBean = null; //文件信息Bean ]u O|YLWp  
long[] nStartPos; //开始位置 }W R?n  
long[] nEndPos; //结束位置 ;=ERm=  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 3H/4$XJB  
long nFileLength; //文件长度 <Okl.Iz>  
boolean bFirst = true; //是否第一次取文件 Jro%zZle  
boolean bStop = false; //停止标志 -u'BK@;
  
File tmpFile; //文件下载的临时信息 M6b6lhg  
DataOutputStream output; //输出到文件的输出流 )eSD5hOI)  
.3T#:Hl  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 1:iT#~n  
public SiteFileFetch(SiteInfoBean bean) throws IOException ?`D/#P  
{ Y]t)k9|vv  
siteInfoBean = bean; V\o&{7!  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 0j|JyS:}G  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); w!^{Q'/,Q  
if(tmpFile.exists ()) PP)-g0^@  
{ iYxpIqWw  
bFirst = false; 5PCKBevV  
read_nPos(); gkDlh{  
} _"%-=^_  
else `~3y[j]kO  
{ B mxBbg  
nStartPos = new long[bean.getNSplitter()]; APucA  
nEndPos = new long[bean.getNSplitter()]; '&$xLZ8  
} ZiOL7#QWX  
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} R k).D6  
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public void run() aC2\C=ru_  
{ #\fxU:z~r  
//获得文件长度 VZArdXTP  
//分割文件 n$T'gX#5  
//实例FileSplitterFetch <U() *0  
//启动FileSplitterFetch线程 xT$9M"  
//等待子线程返回 ^8yhx-mgb  
try{ ;4 ON  
if(bFirst) gNG_,+=!  
{ ]1 OZY@  
nFileLength = getFileSize(); r|tTDKGQ  
if(nFileLength == -1) XZFM|=%X  
{ @eGJ_
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System.err.println("File Length is not known!"); 2U;ImC1g  
} tk <R|i  
else if(nFileLength == -2) eO:wx.PW  
{ IZ
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System.err.println("File is not access!"); -?$Hr\  
} z!GLug*j`  
else qEoa%O  
{ ?xuhN G@  
for(int i=0;i<nStartPos.length;i++) J,k|_JO  
{ }XiV$[xHd  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); .UuCTH;6`  
} n^AQ!wC  
for(int i=0;i<nEndPos.length-1;i++) 2& l~8,  
{ hs"=>(P)  
nEndPos = nStartPos[i+1]; "NamP\hj  
} hkq[xgX  
nEndPos[nEndPos.length-1] = nFileLength; X_eh+>D  
} =i/7&gC  
} }t[?g)"M#-  
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VY5/C;0^h  
//启动子线程 KPOr8=Rc  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; _cY!\'  
for(int i=0;i<nStartPos.length;i++)  !Z'x h +  
{ |h; _r&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), dt(#|8i%  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Rx22W:S=C.  
nStartPos,nEndPos,i); iwl\&uNQU  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ljij/C=  
fileSplitterFetch.start(); DhwFD8tT  
} l
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), n%>c4*t  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); (gv1f  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", A@X&dy  
nEndPos = " + nFileLength); .*N,x0B(  
// fileSplitterFetch[nPos.length-1].start(); E K)7g~  
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6mnj!p]3  
//等待子线程结束 xi.L?"^/!  
//int count = 0; y-TS?5Dr]  
//是否结束while循环 R)3P"sGuN  
boolean breakWhile = false; rVx%"_'*-  
#mNM5(o  
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while(!bStop) =W6AUN/%p  
{ RY(\
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write_nPos(); Q}a 1P8?S  
Utility.sleep(500); tf?u ;n  
breakWhile = true; WdGjvs  
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for(int i=0;i<nStartPos.length;i++) J3oj}M*  
{ DL5`A?/  
if(!fileSplitterFetch.bDownOver) 1Y"[Qs]"mU  
{ a3wTcp "r  
breakWhile = false; ^gwVh~j  
break; ]}_@!F)  
} {jX h/`  
} gF@51K  
if(breakWhile) 5h9`lS2  
break; AS34yM(h  
`
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I-E}D"F;p[  
//count++; "(6]K}k@  
//if(count>4) I@l'Fx  
// siteStop(); $q]:m+Fm
 
} ?- 5{XrNm  
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System.err.println("文件下载结束！"); xr uQ=Q  
} tK3.HvD  
catch(Exception e){e.printStackTrace ();} )S
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} &wbe^Wp  
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//获得文件长度 jlV~-}QKb7  
public long getFileSize() h2 2-vX  
{ T-)Ur/qp  
int nFileLength = -1; @;iW)a_M  
try{ 6% @@~"  
URL url = new URL(siteInfoBean.getSSiteURL()); }+KSZ,  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); n{dl-P  
httpConnection.setRequestProperty("User-Agent","NetFox"); fLj#+h-!  
t{\FV@R  
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int responseCode=httpConnection.getResponseCode(); `B+P$K<X  
if(responseCode>=400) iV!o)WvG,F  
{ i]:T{2  
processErrorCode(responseCode); 2f8fA'|O  
return -2; //-2 represent access is error `B{N3Kxbp  
} [HJ^'/bB'  
>yC1X|d~t  
+$KUy>  
String sHeader; Np4';
H  
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for(int i=1;;i++) w(O/mUDX  
{ {{c/:FTEU  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); o+sb2:x  
//Utility.log(in.readLine()); fRp+-QvE  
sHeader=httpConnection.getHeaderFieldKey(i); g@!mV)c97  
if(sHeader!=null) PN ,pEk|  
{ acgtXfHR  
if(sHeader.equals("Content-Length")) Y27x;U  
{ {AbQaw  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); @EZ@X/8{&  
break; 5Z]zul@+*  
} 3 8>?Z]V  
}
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else 1ID0'j$  
break; 7mipj]
 
} ]sBSLEie '  
} c:0nOP  
catch(IOException e){e.printStackTrace ();} ) -+u
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catch(Exception e){e.printStackTrace ();} {_0m0 8  
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Utility.log(nFileLength); -lr)z=})  
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return nFileLength; rPVz!(;k  
} p\]Mf#B  
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//保存下载信息（文件指针位置） 8RJXY:%  
private void write_nPos() 1 "'t5?XW  
{ t|Cp<k]B  
try{ uGIA4CUm  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 1!,xB]v1Ri  
output.writeInt(nStartPos.length); 3.M<ATe^  
for(int i=0;i<nStartPos.length;i++) :<ye:P1s  
{ %|L+~=  
// output.writeLong(nPos); B#Rw
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output.writeLong(fileSplitterFetch.nStartPos); 7%C6hEP/*W  
output.writeLong(fileSplitterFetch.nEndPos); " N)dle,  
} *oAv:8"iY  
output.close(); 0 1U/{D6D  
} ^&oa\7<'  
catch(IOException e){e.printStackTrace ();} 5gnNgt~  
catch(Exception e){e.printStackTrace ();} ]J;pUH+u  
} 2GNtO!B.  
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+uMOT#KjR  
//读取保存的下载信息（文件指针位置） p=m)lR9  
private void read_nPos() Z-3i -(  
{ h#Cq-^D#~  
try{ UR|UGldt_T  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); HvSKR1wL\  
int nCount = input.readInt(); M{gtu'.  
nStartPos = new long[nCount]; -oo&8  
nEndPos = new long[nCount]; G+
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for(int i=0;i<nStartPos.length;i++) yyke"D  
{ T =r7FU  
nStartPos = input.readLong(); BgLW!|T[  
nEndPos = input.readLong(); '=?IVm#C  
} va \5  
input.close(); fZU#%b6G  
} +g8wc(<ik  
catch(IOException e){e.printStackTrace ();} HMyw:?  
catch(Exception e){e.printStackTrace ();} ?;!d5Xuu  
} UELni,$  
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private void processErrorCode(int nErrorCode) <}S1ZEZcQ  
{ B{'x2I#,  
System.err.println("Error Code : " + nErrorCode); 5y07@x  
} YEF|SEon0  
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//停止文件下载 tFLdBv!=:^  
public void siteStop() |_Vi8Ly  
{ zlC|Spaf  
bStop = true; j0b?dK
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for(int i=0;i<nStartPos.length;i++) pC 5J '@  
fileSplitterFetch.splitterStop(); }HB)%C50.  
8F|8zX&  
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} smEKQHB  
} rW$ )f  
//负责部分文件的抓取 E-,/@4k  
**FileSplitterFetch.java EU?)AxH^  
*/ P?%kV  
package NetFox; bp G
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import java.io.*; 7kmU/(8  
import java.net.*; $Lpt2:.((  
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public class FileSplitterFetch extends Thread { =fmM=@!$<  
=C{)i@ +  
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String sURL; //File URL 49b#$Xq  
long nStartPos; //File Snippet Start Position &|('z\k  
long nEndPos; //File Snippet End Position n(^{s5 Rr  
int nThreadID; //Thread's ID 4qq+7B  
boolean bDownOver = false; //Downing is over $]:ycn9l  
boolean bStop = false; //Stop identical 2O\p`,.  
FileAccessI fileAccessI = null; //File Access interface # Vz9j  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException k(|D0%#b7  
{ 69{^Vfd;Y  
this.sURL = sURL; 1U[8OM{$  
this.nStartPos = nStart; k.nq,  
this.nEndPos = nEnd; u
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nThreadID = id; ud]O'@G<  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 FHpS?htRy  
} j:'sbU  
g.-{=kZ   
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public void run() g:0-`,[  
{ ER0nrTlB<  
while(nStartPos < nEndPos && !bStop) +92/0
 
{ v%O KOrJ  
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((i%h^tGa;  
try{ +4G]!tV6  
URL url = new URL(sURL); 8[  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 7UQFAt_r  
httpConnection.setRequestProperty("User-Agent","NetFox"); %00KOM:
 
String sProperty = "bytes="+nStartPos+"-"; PveY8[i  
httpConnection.setRequestProperty("RANGE",sProperty); tr8a_CV  
Utility.log(sProperty); e|x1Dq  
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InputStream input = httpConnection.getInputStream(); 2QwdDKMS_  
//logResponseHead(httpConnection); O>]I!n`!!A  
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byte[] b = new byte[1024]; nNNs3h(Ss  
int nRead; <SeK3@Gi  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) =0,:w(Sb!  
{ ]?!#*<t r  
nStartPos += fileAccessI.write(b,0,nRead); R;+vE'&CO  
//if(nThreadID == 1) W]E6<y'  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); eSvS<\p  
} b77
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Utility.log("Thread " + nThreadID + " is over!"); 7:7i}`O  
bDownOver = true; bup)cX^  
//nPos = fileAccessI.write (b,0,nRead); ,PH;j_  
} yV
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catch(Exception e){e.printStackTrace ();} IC&>PwXb  
} (>O'^W\3p  
} l-` M 9#  
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//打印回应的头信息 C3EQzr`  
public void logResponseHead(HttpURLConnection con)
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{ Ny_d  
for(int i=1;;i++) )C^ZzmB  
{ fFu+P<?"  
String header=con.getHeaderFieldKey(i); w1q-bIU  
if(header!=null) VJW%y)_[  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ug]WIG7 S  
Utility.log(header+" : "+con.getHeaderField(header)); %j3XoRex><  
else Ox.6]W~  
break; z ((Y\vP  
} ;S Re`  
} (+SfDL$m  
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9<qAf`  
public void splitterStop() [n%=2*1p  
{ J1P jM
b}  
bStop = true; Ph@hk0dgr/  
} ~>8yJLZ.7  
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u.!}s2wT#  
} )anprhc  
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/* dk<) \C"  
**FileAccess.java W=zHD9  
*//文件访问(定位，写) }<m'Nkz<X  
package NetFox; )1#J4  
import java.io.*; -U&k%X   
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public class FileAccessI implements Serializable{ f]c{,LFvZ  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 BO5\rRa0  
RandomAccessFile oSavedFile; +5AWX,9,-  
long nPos; l@
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public FileAccessI() throws IOException FU]jI[  
{ p./9^S  
this("",0); ngmHiI W  
} ,3+#?H  
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public FileAccessI(String sName,long nPos) throws IOException IR_&dWHyc  
{ cp| q  
oSavedFile = new RandomAccessFile(sName,"rw"); /6Bm <k%  
this.nPos = nPos; BqoGHg4iq  
oSavedFile.seek(nPos); ks3ydHe`  
} n-djAhy  
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public synchronized int write(byte[] b,int nStart,int nLen) \0)v5u  
{ r Uau??  
int n = -1; x-E@[=  
try{ 4$~A%JN3  
oSavedFile.write(b,nStart,nLen); m$XMq  
n = nLen; wk+| }s  
} >#u9W'@|  
catch(IOException e) wqx9  
{ O0`o0!=P  
e.printStackTrace (); <m"fzT<"  
} zDD  
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}BFX7X  
return n; 7+'&(^c  
} zCz"[9k  
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} ~<.%sVwE  
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lf`" (:./  
/* obzdH:S  
**SiteInfoBean.java 7)-uYi] dA  
*/ wZe>}1t  
package NetFox; %fJ~3mu  
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public class SiteInfoBean { jjJvyZi~J  
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private String sSiteURL; //Site's URL i]$
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private String sFilePath; //Saved File's Path BV"l;&F[  
private String sFileName; //Saved File's Name lZ'Z
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private int nSplitter; //Count of Splited Downloading File v#^_|  
S UBrFsA  
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public SiteInfoBean() j|-{*t{/x  
{//nSplitter的缺省值为5 s#BSZP  
//default value of nSplitter is 5 As>-9p>v  
this("","","",5); F2)\%HR  
} z*ly`-!  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) `ElJL{Rn  
{ +~n"@ /  
sSiteURL= sURL; /ka "YU  
sFilePath = sPath; r?%,#1|$$  
sFileName = sName; rds4eUxe  
this.nSplitter = nSpiltter; 4R}$P1 E  
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} ;659E_y>  
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public String getSSiteURL() WF_24Mw  
{ `p#u9M>  
return sSiteURL; Q=u [j|0mc  
}  [1Q:  
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public void setSSiteURL(String value) SdXAL  
{ Ue&I]/?;$  
sSiteURL = value; |Duf 3u  
} c~)H" n  
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public String getSFilePath() =`EVg>+^  
{
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return sFilePath; }$oZZKS  
} \R.Fmeko  
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public void setSFilePath(String value) z{(c-7*  
{ 
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sFilePath = value; wDt9Lf O  
} 82P#C4c+d  
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public String getSFileName() _edT+r>+  
{ 7Um3myXU  
return sFileName; [pzo[0G 'v  
} &`B Tw1u  
3e?a$~9  
Gj- *D7X5  
public void setSFileName(String value) #eY?6Kjn  
{ /g\m7m)u  
sFileName = value; -&0HAtc  
} js[H $  
tD+K4 ^  
=SK{|fBB  
public int getNSplitter() *kq>Z 06'i  
{ &\5%C\0Z<  
return nSplitter; A)HV#T`N  
} ;@/vKA3l.  
iu+rg(*%  
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public void setNSplitter(int nCount) oL
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{ v"V?  
nSplitter = nCount; pKhV<MFB  
} 9;L50q>s  
} ~PA6e+gmL  
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/* wh#x`Nc  
**Utility.java MB"<^ZX  
*/ mApl}I  
package NetFox; q/dja  
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~
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public class Utility { ;hkzL_' E)  
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public Utility() - %`iLu  
{ *:,y`!F=y  
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} ,7^,\ ,-m  
-3|i5
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//线程睡眠 }
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public static void sleep(int nSecond) 9RnXp&w  
{ 0
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try{ Ir$:e*E>  
Thread.sleep(nSecond); o(3`-ucD`  
} `cpUl*Y=  
catch(Exception e) >-4kO7.V  
{ ;0Mg\~T~'  
e.printStackTrace (); > m##JzWLr  
} NSDls@m  
} l3;MjNB^V  
ky{-NrK  
//日志 DtOL=m]s  
public static void log(String sMsg) w<G'gi]  
{ ~,O}wT6q  
System.err.println(sMsg); &/{x7;e  
} 1ZRSeh  
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P
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public static void log(int sMsg) r|JZU  
{ RtScv  
System.err.println(sMsg); t.6gyrV7><  
} N-<m/RS  
} 3PRK.vf  
x L]Z3"p%  
=J827c{.  
/* x[1(cj  
**TestMethod.java BZs?tbf  
*/ \"AzT{l!;  
package NetFox; zR6^rq*  
%#-'|~  
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public class TestMethod {
"&N1$$  
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public TestMethod() i~;Yrc%AEX  
{ ///xx/weblogic60b2_win.exe <|c[
#f  
try{ r^$WX@ t&  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 4KT-U6zNx  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); UWW_[dJr  
SiteFileFetch fileFetch = new SiteFileFetch(bean); hwB>@r2  
fileFetch.start(); M$+2f.(>k)  
} 0\Ga&Q0-(O  
catch(Exception e){e.printStackTrace ();} <O30X !QuK  
n;0x\Q|S  

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} YDdY'd`*  
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 4xnM7t\  
public static void main(String[] args) 4Q5c'  
{ rhvTV(Bz  
new TestMethod(); _)F0oC {  
} sN9 SuQ  
} .qG*$W2f  
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