http断点续传简单实现（java)

/* UX.rzYM&T  
**SiteFileFetch.java b`^?nD7  
*/ N2k{@DY  
package NetFox; A )CsF  
import java.io.*; ,1lW`Krx  
import java.net.*; '&K' 0qG  
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public class SiteFileFetch extends Thread { X%fLV(  
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SiteInfoBean siteInfoBean = null; //文件信息Bean \yxGE+~P  
long[] nStartPos; //开始位置 3webAaO  
long[] nEndPos; //结束位置 &TrL!9FtJ  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 >1]hR)Ip  
long nFileLength; //文件长度 sCQV-%9  
boolean bFirst = true; //是否第一次取文件 ^T1caVb|>  
boolean bStop = false; //停止标志 Us2> 5 :\  
File tmpFile; //文件下载的临时信息 ,1JQjsR   
DataOutputStream output; //输出到文件的输出流 hb/Z{T'  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） es.Y  
public SiteFileFetch(SiteInfoBean bean) throws IOException >TawJ"q-6R  
{ Nlwt}7  
siteInfoBean = bean; qD=b+\F  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));  CWYOzqf  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); qt"6~r!  
if(tmpFile.exists ()) vk(I7  
{ 7M5HvG#w%  
bFirst = false; a\Gd;C ^`  
read_nPos(); Nl%5OBm  
} 5INw#1~  
else 
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{ CtD<%v3`  
nStartPos = new long[bean.getNSplitter()]; XtBEVqrhi  
nEndPos = new long[bean.getNSplitter()]; j> dZ26 >N  
} yT7{,Z7t  
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} XbFo#Pwk  
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public void run() ?6x&A t  
{ yGC HWP  
//获得文件长度 }NdLd!  
//分割文件 !,5qAGi0  
//实例FileSplitterFetch DZb0'+jQ  
//启动FileSplitterFetch线程 aM,g@'.=  
//等待子线程返回 2~r2ErtS  
try{ v~._]f$:  
if(bFirst) s=E6HP@q  
{ K>XZrt  
nFileLength = getFileSize(); J#iuF'%Ds  
if(nFileLength == -1) wq1s#ag<  
{ `w@z Fc!"  
System.err.println("File Length is not known!"); 5bI4' ;  
} 4 EA$<n(A-  
else if(nFileLength == -2) 7*Zm{r@u  
{ ,lFzL3'_0x  
System.err.println("File is not access!"); 'X/:TOk{W  
} mYXL  
else ) R\";{`M  
{ ]_|%!/_  
for(int i=0;i<nStartPos.length;i++) "e>9R'y  
{ YWV)C?5x&  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); d0zp89BEn  
} UX|3LpFX&I  
for(int i=0;i<nEndPos.length-1;i++) t0P_$+w.>  
{ Y(K`3?A  
nEndPos = nStartPos[i+1]; 55y{9.n*  
} -JFW ,8=8  
nEndPos[nEndPos.length-1] = nFileLength; >Kl_948  
} aE"dpYQ  
} 1}ifJ~)5S  
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//启动子线程 ATmyoN2@>  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ,5 
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for(int i=0;i<nStartPos.length;i++) j0Os]a  
{ 19oyoi"  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), d+

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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 3(.Y>er%U  
nStartPos,nEndPos,i); k{ZQM  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [W<j  
fileSplitterFetch.start(); LHA:frC  
} 5C*-v,hF  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), A L|,\s  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); >:FmAey  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ?"?AH/ED  
nEndPos = " + nFileLength); 'C:i5?zh(q  
// fileSplitterFetch[nPos.length-1].start(); Rx.5;2m  
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Lc-WfzT  
//等待子线程结束 &rG]]IO  
//int count = 0; iP$>/[I  
//是否结束while循环
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boolean breakWhile = false; X .K*</(g  
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while(!bStop) j*1MnP3/8Y  
{ ^ ~Tn[w W_  
write_nPos(); ;vpq0t`  
Utility.sleep(500); W}(T5D" 3x  
breakWhile = true; j4=\
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for(int i=0;i<nStartPos.length;i++) QNXS.!\P  
{ W3%RB[s-  
if(!fileSplitterFetch.bDownOver) 0}9jl  
{ k@[[vj|W  
breakWhile = false; p2+K-/}ApP  
break; i.-2 w6  
} CWd &  
} Z 6][9o  
if(breakWhile) Q!7mN?l  
break; {)Wa"|+  
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//count++; >.XXB 5a  
//if(count>4) x{rjngp2  
// siteStop(); Q yQ[H  
} \y7Gi}nI  
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System.err.println("文件下载结束！"); ,hT**(W  
} ;2sP3!*  
catch(Exception e){e.printStackTrace ();} KWi|7z(L=  
} %S>6Q
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//获得文件长度
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public long getFileSize() |0_5iFAB|  
{ E?Qg'|+_  
int nFileLength = -1; jD6T2K7i  
try{ +p]@b  
URL url = new URL(siteInfoBean.getSSiteURL()); 'S=eW_ 0/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6&2{V? W3  
httpConnection.setRequestProperty("User-Agent","NetFox"); _C'VC#Sy  
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int responseCode=httpConnection.getResponseCode(); *ck'vV'@  
if(responseCode>=400) XuU>.T$]c  
{ xa{.hp?  
processErrorCode(responseCode); lhBAT%U\  
return -2; //-2 represent access is error D>-Pv-f/  
} vrvi] Y8  
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String sHeader; OE}c$!@  
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for(int i=1;;i++) D<*)^^  
{ Q7mikg=1-  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ZA'0q  
//Utility.log(in.readLine()); -KqMSf&9  
sHeader=httpConnection.getHeaderFieldKey(i); 'loko#6  
if(sHeader!=null) /c7jL4oD  
{ (^<skx>  
if(sHeader.equals("Content-Length")) =#&+w[4?&.  
{ N)K
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); kn&BGYt  
break; N[yS heT  
} Qv8 =CnuOT  
} W{ZJ^QAq/  
else )E6E
}  
break; GAh\6ul  
} H8Z|gq1r  
} &nY#GHB  
catch(IOException e){e.printStackTrace ();} O}6*9X
y  
catch(Exception e){e.printStackTrace ();} ydE}.0zN  
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Utility.log(nFileLength); ykxAm\O  
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return nFileLength; 8N4E~*>C  
} Ir5E*op7D  
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//保存下载信息（文件指针位置） }0OQm?xh  
private void write_nPos() S*WLb/R2  
{ x3nUKQtk:8  
try{ nKjT&R  
output = new DataOutputStream(new FileOutputStream(tmpFile)); wi
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output.writeInt(nStartPos.length); &uf|Le4  
for(int i=0;i<nStartPos.length;i++) x5M+\?I<2  
{ Sa:;j4  
// output.writeLong(nPos); 5tY/d=\k  
output.writeLong(fileSplitterFetch.nStartPos); ^<j =.E  
output.writeLong(fileSplitterFetch.nEndPos); 5`::#[  
} }=u#,nDl>$  
output.close(); D28>e  
} q$}gQ9'z'  
catch(IOException e){e.printStackTrace ();} 71\GK  
catch(Exception e){e.printStackTrace ();} g$qM}#s0}  
} uaha)W;'9  
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//读取保存的下载信息（文件指针位置） Bc<pD?uOK  
private void read_nPos() ?07}\N0~  
{ q'uGB fE.  
try{ LO38}w<k  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Y&$puiH-j  
int nCount = input.readInt(); x l=i_  
nStartPos = new long[nCount]; Lo=n)cV1,  
nEndPos = new long[nCount]; TT&%[A+  
for(int i=0;i<nStartPos.length;i++) :fnK`RnaQ  
{ 6 8Vxy  
nStartPos = input.readLong(); iY5V4Gbo  
nEndPos = input.readLong(); !3z ;u8W  
} 1buO&q!vn  
input.close(); _93:_L  
} 7~L_>7;  
catch(IOException e){e.printStackTrace ();} -NA2+].  
catch(Exception e){e.printStackTrace ();} O5*3 qJp  
} $A T kCO  
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private void processErrorCode(int nErrorCode) <%=<9~e  
{ D@c@Dt  
System.err.println("Error Code : " + nErrorCode); fC$@m_-KD  
} ]q&NO(:kbq  
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}!m}?  
//停止文件下载 ?Q"1zcX  
public void siteStop() ?0lz!Nq'S  
{ 9H+Q/Q*-a  
bStop = true; }|Bs|$q  
for(int i=0;i<nStartPos.length;i++) :b;`.`@KL_  
fileSplitterFetch.splitterStop(); zqp>Xw  
^^*Ia'9   
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} ciFqj3JS  
} 0(o.[%Ye  
//负责部分文件的抓取 h]j>S  
**FileSplitterFetch.java ;f} ']2  
*/ pfFHuS~  
package NetFox; |ZOdfr4uW  
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import java.io.*; vD(:?M  
import java.net.*; + 7wMM#z  
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public class FileSplitterFetch extends Thread { r4
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String sURL; //File URL j@{dsS:6  
long nStartPos; //File Snippet Start Position .-Dc%ap
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long nEndPos; //File Snippet End Position al7D3J  
int nThreadID; //Thread's ID >qd=lm <,  
boolean bDownOver = false; //Downing is over buhbUmQ2  
boolean bStop = false; //Stop identical Q&/WVRD  
FileAccessI fileAccessI = null; //File Access interface i4&V+h"  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException j}6h}E&dEr  
{ V~do6[(  
this.sURL = sURL; tjx|;m7  
this.nStartPos = nStart; ZEvK
 
this.nEndPos = nEnd; )g KC}_h=  
nThreadID = id; g2A#BMe'.$  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 >B;KpO"+m  
} ]kF1~kXBe  
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public void run() %OP|%^2  
{ ^sqzlF  
while(nStartPos < nEndPos && !bStop) M0`1o p1  
{ p8Z;QH*  
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try{ s-~`Ao' <  
URL url = new URL(sURL); DgB;6Wl  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _CBMU'V  
httpConnection.setRequestProperty("User-Agent","NetFox"); "/Gw`^t  
String sProperty = "bytes="+nStartPos+"-"; c:<a"$  
httpConnection.setRequestProperty("RANGE",sProperty); Z$zX%w  
Utility.log(sProperty); d]N_<@tx9  
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InputStream input = httpConnection.getInputStream(); 5hTScnL%  
//logResponseHead(httpConnection); `7[!bCl  
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byte[] b = new byte[1024]; ln8es{q  
int nRead; 7nP{a"4_  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) W_,7hvE?"H  
{ KL$>j/qT  
nStartPos += fileAccessI.write(b,0,nRead); W>:MK-_J  
//if(nThreadID == 1) NQqNBI?cr  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `,4@;j<^@  
} Bx6,U4o*  
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Utility.log("Thread " + nThreadID + " is over!"); c;zk{dP   
bDownOver = true; |nGv:= H@
 
//nPos = fileAccessI.write (b,0,nRead); |$~]|SK  
} v5U'ky:  
catch(Exception e){e.printStackTrace ();} 9<3fH J?vq  
} #zBqj;p  
} u7j,Vc'~  
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//打印回应的头信息 S(CVkCP  
public void logResponseHead(HttpURLConnection con) q- 0q:  
{ G5RdytK  
for(int i=1;;i++) u]i%<Yy89  
{
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String header=con.getHeaderFieldKey(i); %5nEyZOq  
if(header!=null) %~,Fe7#p  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); R.vOYzo  
Utility.log(header+" : "+con.getHeaderField(header)); ,+I]\ZeO  
else %s^1de  
break; G;EJ\J6@Yw  
} 23 #JmR  
} t*H|*L#YR  
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x  
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public void splitterStop() t)rPXvx}!  
{ 0WYu5|  
bStop = true; '2|P-/jU  
} Mc!LC .8  
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} b#R$P]dr=  
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/* jzBW'8  
**FileAccess.java _*b`;{3  
*//文件访问(定位，写) jicH94#(]  
package NetFox; .GL@`7"  
import java.io.*; }[h]z7e2S  
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public class FileAccessI implements Serializable{ `l/nAKg?W  
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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  :8==Bu  
RandomAccessFile oSavedFile; >G
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long nPos; po,Ue>n/  
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public FileAccessI() throws IOException H)EL0 Kv/  
{ OEXa}K#  
this("",0); rm$dv%q  
} R.Fl5B  

} #L_R  
r/"^{0;F{W  
public FileAccessI(String sName,long nPos) throws IOException dUl"w`3  
{ kqxq'Aq)d  
oSavedFile = new RandomAccessFile(sName,"rw"); @^ *62  
this.nPos = nPos; X%kJ3{  
oSavedFile.seek(nPos); 7YK6e  
} >]C/ Q6  
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public synchronized int write(byte[] b,int nStart,int nLen) AE~@F4MK  
{ dqo-
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int n = -1; 1~3dX[&  
try{ 5MKM;6cA&p  
oSavedFile.write(b,nStart,nLen); 2oRwDg&7|  
n = nLen;  ;Q4,I[?%  
} aDxNAfP  
catch(IOException e) AXSip  
{ YRr,{[e  
e.printStackTrace (); Un,'a8>V`  
} udIm}jRA"  
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return n; .:B>xg~2  
} );6f8H@G  
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} `Syfl^9B  
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/* v+`'%E  
**SiteInfoBean.java R5((
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*/ }4H}*P>+  
package NetFox; WBkx!{\z  
jm@M"b'{  
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public class SiteInfoBean { /h.{g0Xc  
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private String sSiteURL; //Site's URL hsS&|7Pt  
private String sFilePath; //Saved File's Path
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private String sFileName; //Saved File's Name ,|>>z#Rr(n  
private int nSplitter; //Count of Splited Downloading File JtxVF!v  
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public SiteInfoBean() jw{B8<@s  
{//nSplitter的缺省值为5 ->.9[|lIg  
//default value of nSplitter is 5 ",Vx.LV  
this("","","",5); RWo7_XO  
} "`cPV){]  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) |YyNqwP`,  
{ un -h%-e|  
sSiteURL= sURL; Ql l{;A  
sFilePath = sPath; 5(hv|t/a  
sFileName = sName; v1X[/\;U  
this.nSplitter = nSpiltter; T4"D&~3 3q  
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;v2eAe@7  
} 0)~c)B:5  
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public String getSSiteURL() %O"Whe  
{ ,+6u6  
return sSiteURL; ruB D ^-  
} g<M!]0OK  
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public void setSSiteURL(String value) ujmIS~"  
{ j|K;Yi  
sSiteURL = value; r<!nU&FPD:  
} a|oh Ad  
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public String getSFilePath() ~n%Lo3RiP  
{ ) 5$?e  
return sFilePath; ~+Pe=~a[  
}
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public void setSFilePath(String value) y_Urzgm(  
{ F`x_W;\  
sFilePath = value; g)r{LxT#+  
} =RRv& "2r  
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public String getSFileName() g
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{ #G F.M,O/h  
return sFileName; 0D '^:  
} _80L/92  
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public void setSFileName(String value) o
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{ Q
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sFileName = value; 0!0e$!8l  
} F!)[H["_  
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public int getNSplitter() ]j
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{ )lS04|s  
return nSplitter; `NgQ>KV!  
} _
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public void setNSplitter(int nCount) l/zv >  
{ MkJBKS  
nSplitter = nCount; qAH^BrJ  
} $6wSqH?q  
} \OFmd!Cz  
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/* Komdz/g  
**Utility.java }s<;YC  
*/ ?z l<"u  
package NetFox; -wV2 79^b  
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public class Utility { #\Rxqh7  
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public Utility() XL.f`N.O  
{ <iU@ M31  
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} } f&=}  
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//线程睡眠 ,;w~ VZ4  
public static void sleep(int nSecond) Y]0
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{ FVrB#Hw~  
try{ nf"#F@dk  
Thread.sleep(nSecond); +<[q"3
  
} uE9,N$\L_  
catch(Exception e) 7R:Ij[dV  
{ a<r,LE  
e.printStackTrace (); ez[x8M>  
} f7Nmvla[q  
} Ul]7IUzsu  
`j)56bR  
//日志 W5`pQdk  
public static void log(String sMsg) CQ/+- -o  
{ Eq;w5;7s  
System.err.println(sMsg); aaY AS"/:  
} ij-'M{f  
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!Ea!"}  
public static void log(int sMsg) -;_"Y]#  
{ AJ*17w  
System.err.println(sMsg); SIrNZ^I  
} 7A(4`D J  
} 0Pf88'6  
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"ufSHrZv  
/* ]j/= x2p  
**TestMethod.java *,lDo9  
*/ :g63*d+/G  
package NetFox; 67Pmnad  
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public class TestMethod { 4uoZw3O  
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k $gcQ:|  
public TestMethod() eu$VKLY*  
{ ///xx/weblogic60b2_win.exe 9 CZ@IFS  
try{ _^GBfM.  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); mm:TR?^  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); )Wq1af   
SiteFileFetch fileFetch = new SiteFileFetch(bean); ^il$t]X5-  
fileFetch.start(); :h34mNU
 
} ff.k1%wr^  
catch(Exception e){e.printStackTrace ();} HLV8_~gQPf  
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} -Z,r\9d  
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public static void main(String[] args) 0$Rn|yqf%  
{ dNt^lx  
new TestMethod(); vkGF_aenk  
} |wuTw|  
} A)
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