http断点续传简单实现（java)

/* !%/(a)B$^$  
**SiteFileFetch.java nT=XWM  
*/ G|qsJ  
package NetFox; BB.120v&N  
import java.io.*; [H{2<!  
import java.net.*; 'k/:3?R  
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public class SiteFileFetch extends Thread { r)oR`\7  
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SiteInfoBean siteInfoBean = null; //文件信息Bean l4\!J/df  
long[] nStartPos; //开始位置 {}"a_L&[;  
long[] nEndPos; //结束位置 hQaa"U7[  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 /g$8JL  
long nFileLength; //文件长度 Qb'Q4@.  
boolean bFirst = true; //是否第一次取文件 +.McC$!s  
boolean bStop = false; //停止标志 0Z jE(3i  
File tmpFile; //文件下载的临时信息 C#P7@JE  
DataOutputStream output; //输出到文件的输出流 4tz@?TCb  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） yQ| V7G  
public SiteFileFetch(SiteInfoBean bean) throws IOException E51S#T  
{ %XH%.Ps/  
siteInfoBean = bean; I$*LMzve  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 4{LKT^(!f  
if(tmpFile.exists ()) ~9c jc  
{ :"`1}Q  
bFirst = false; VlS`m,:{  
read_nPos(); "=yz
}~,  
} UoHNKB73  
else zin'&G>l  
{ lKV7IoJ&;  
nStartPos = new long[bean.getNSplitter()]; fhmBKeFdV  
nEndPos = new long[bean.getNSplitter()]; '}E"Mdb  
} s"x(i  
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} (>`S{L C>s  
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public void run() /l;_ xs  
{ )u
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//获得文件长度 #=#bv`  
//分割文件 60r0O5=|Fl  
//实例FileSplitterFetch `Db%:l^e  
//启动FileSplitterFetch线程 8" (j_~;  
//等待子线程返回 [9\Mf4lh#  
try{ %9_jF"  
if(bFirst) W/u_<\  
{ E+~
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nFileLength = getFileSize(); r=<1*u  
if(nFileLength == -1) Xuj=V?5  
{ .B{:<;sa  
System.err.println("File Length is not known!"); f9^MLb6)  
} z;\,
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else if(nFileLength == -2) Aq_?8Cd  
{ @m9dB P  
System.err.println("File is not access!"); qm"AatA  
} IY}{1[<N  
else _vUId?9@+e  
{ #-kx$(''V  
for(int i=0;i<nStartPos.length;i++) @[~j|YH}  
{ >[4CQK`U  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); nk2H^RM^  
} q5~"8]Dls  
for(int i=0;i<nEndPos.length-1;i++) @Op7OFY%  
{ Qk].^'\  
nEndPos = nStartPos[i+1]; rDC=rG  
} >g2Z t;*@w  
nEndPos[nEndPos.length-1] = nFileLength; cCqmrjUmV  
} As(6E}{S  
} G<`6S5J>hr  
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//启动子线程 2E@g#:3  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ;qaNIOo9  
for(int i=0;i<nStartPos.length;i++) J['i  
{ Xe@:Aun  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), N`+@_.iBX  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), $mn+  
nStartPos,nEndPos,i); AhQsv.t   
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); o= &/;X  
fileSplitterFetch.start(); iy [W:<c7j  
} q
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), gFr-P!3  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); (4C_Ft*~j  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ,9~qLQ0O  
nEndPos = " + nFileLength); 8!qzG4F/  
// fileSplitterFetch[nPos.length-1].start(); !uAqY\Is  
nI,-ftMD-|  
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//等待子线程结束 >!%+)  
//int count = 0; ~!"z`&
  
//是否结束while循环 %h&F  
boolean breakWhile = false; #%.fsJNA$  
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while(!bStop) :nxBM#:xu  
{ hf5+$^RZ  
write_nPos(); yXCJ?  
Utility.sleep(500); hh<ryuZ  
breakWhile = true; APqYf<W  
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for(int i=0;i<nStartPos.length;i++) tWA<OOl  
{ (`&E
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if(!fileSplitterFetch.bDownOver) "$ep=h+  
{ P5`BrY,hZ  
breakWhile = false; b.QL\$a &  
break; K#[z5  
} uw{K&Hxw  
} imZ"4HnPP  
if(breakWhile) 0w?G&jjNtM  
break; Jv59zI  
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u
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//count++; .CEl{fofj  
//if(count>4) k.W1bF9n6  
// siteStop(); pZ&?u
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} Df=Xbf>jt9  
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System.err.println("文件下载结束！"); z;PF%F  
} T;{"lp.  
catch(Exception e){e.printStackTrace ();} G>S3?jGk  
} )\QPUdOvx  
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//获得文件长度 5.F/>?<  
public long getFileSize() #NQx(C  
{ M+Eg{^ q`  
int nFileLength = -1; p~h[4hP  
try{ ""x>-j4  
URL url = new URL(siteInfoBean.getSSiteURL()); Frum@n  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); O.$O
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httpConnection.setRequestProperty("User-Agent","NetFox"); y1kI^B  
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int responseCode=httpConnection.getResponseCode(); h]p$r`i7  
if(responseCode>=400) }cERCS\t  
{ Ex4)R2c*  
processErrorCode(responseCode); bs?&;R.5  
return -2; //-2 represent access is error
2;`WI:nt  
} DQ%(X&k  
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String sHeader; xs$.EY:k  
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for(int i=1;;i++) :zsMkdU  
{ `f\+aD'u  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ,*g.?q@W2  
//Utility.log(in.readLine()); O*m9qF<  
sHeader=httpConnection.getHeaderFieldKey(i); dS;Ui]/J  
if(sHeader!=null) \>c1Z5H>  
{ TS@U0Ror  
if(sHeader.equals("Content-Length")) iKAqM{(  
{ D@`"99z  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); %(izKJl q  
break; /H :Bu  
} H<ZXe!q(nx  
} |!uC [=  
else ?xb2jZ/0X  
break; V(3rTDg  
} #hh7fE'9  
}  @zSj&4  
catch(IOException e){e.printStackTrace ();} (?kCo  
catch(Exception e){e.printStackTrace ();} !c=EB`<*  
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Utility.log(nFileLength); ?EA
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return nFileLength; {|R +|ow  
} la89>pF  
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//保存下载信息（文件指针位置） A5%cgr
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private void write_nPos() ky@DH(^>  
{ /[>zFYaQ  
try{ ~ ve  
output = new DataOutputStream(new FileOutputStream(tmpFile)); $QJ,V~  
output.writeInt(nStartPos.length); 4\(|V fy  
for(int i=0;i<nStartPos.length;i++) ,Zb_Pu   
{ .5+5ca  
// output.writeLong(nPos); #E@X'jwu  
output.writeLong(fileSplitterFetch.nStartPos); vz`r !xj)  
output.writeLong(fileSplitterFetch.nEndPos); @S?D}myD  
} J9XV:)Yv#  
output.close(); c}D>.x|]  
} yvV]|B@sO  
catch(IOException e){e.printStackTrace ();} 1L<X+,]@  
catch(Exception e){e.printStackTrace ();} G33'Cgo:,  
} xqzB=0  
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}Fb966 $  
//读取保存的下载信息（文件指针位置） E9:p A5H-j  
private void read_nPos() yI8 /m|  
{ Tizjh&*^  
try{ T*zy^we  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); yrV]I(Xe  
int nCount = input.readInt(); <<+Hs/ ]  
nStartPos = new long[nCount]; bXK$H=S Bz  
nEndPos = new long[nCount]; 2hE+Om^n  
for(int i=0;i<nStartPos.length;i++) Q7SRf$4  
{ XMm(D!6  
nStartPos = input.readLong(); vL~j6'  
nEndPos = input.readLong(); +*KDtqZjk  
} S<"`9r)av  
input.close(); ~ ]^<*R  
} +V/mV7FK  
catch(IOException e){e.printStackTrace ();} }
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catch(Exception e){e.printStackTrace ();} ]M/*Beh  
} J3AS"+]  
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private void processErrorCode(int nErrorCode) G?v]|wdI  
{ 0A.9<&Lod  
System.err.println("Error Code : " + nErrorCode); o3>D~9  
} E?F?)!%  
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_43 :1!os  
//停止文件下载 3R ZD=`  
public void siteStop() znu[i&\=  
{ i`" L?3T  
bStop = true; JsbH'l  
for(int i=0;i<nStartPos.length;i++) (Q ~<>  
fileSplitterFetch.splitterStop(); D8wZC'7  
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} M;1B}x@  
} aXyg`CDv  
//负责部分文件的抓取 5'"l0EuD  
**FileSplitterFetch.java Mgc|>#=  
*/ H&=3rkX  
package NetFox; Dv-ubki  
&*!) d"  
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import java.io.*; iM{UB=C  
import java.net.*; ~OOD#/  
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public class FileSplitterFetch extends Thread { _-bEnF+/0  
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String sURL; //File URL 6sl2vHzA  
long nStartPos; //File Snippet Start Position L+d4&x  
long nEndPos; //File Snippet End Position Y<9Lqc.i  
int nThreadID; //Thread's ID Q^\f,E\S  
boolean bDownOver = false; //Downing is over Pqb])-M9p  
boolean bStop = false; //Stop identical ]>k>Z#8E*  
FileAccessI fileAccessI = null; //File Access interface r
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException lO5*n|Ic,  
{ \A/??8cgXs  
this.sURL = sURL; y/yg-\/XF  
this.nStartPos = nStart; {B+{2;Zk  
this.nEndPos = nEnd; "ba>.h,#'  
nThreadID = id; y|[YEY U)  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Y#aHGZ$i  
} rH5'+x K  
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public void run() d@,3P)?  
{ +5IC-=ZB  
while(nStartPos < nEndPos && !bStop) _!C'oG6s?  
{ {\zB'SNq  
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try{ }wR&0<HA  
URL url = new URL(sURL); EHY}gG)  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); @8s:,Y_  
httpConnection.setRequestProperty("User-Agent","NetFox"); QR]61v:`  
String sProperty = "bytes="+nStartPos+"-"; XH{P@2~l  
httpConnection.setRequestProperty("RANGE",sProperty); nPo YjQi  
Utility.log(sProperty); E< Ini'od[  
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InputStream input = httpConnection.getInputStream(); @E@5/N6M  
//logResponseHead(httpConnection); j,i> 1|J  
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byte[] b = new byte[1024]; GMRFZw_M  
int nRead; 8WvQ[cd  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) v05B7^1@_  
{ 5/"&C-t  
nStartPos += fileAccessI.write(b,0,nRead); A~7q=
-  
//if(nThreadID == 1) ;fnE"}  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "=ogO/_Q"  
} 8{iFxTz  
{ WW!P,w  
N J_#;t#j  
Utility.log("Thread " + nThreadID + " is over!"); wSP'pM{#2  
bDownOver = true; 0?d}Oj  
//nPos = fileAccessI.write (b,0,nRead); _ BUD~'Q5  
} qD/X
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catch(Exception e){e.printStackTrace ();} i!9|R)c  
} It8m]FN  
} 9#A&Qvyywg  
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//打印回应的头信息 #X?#v7i",D  
public void logResponseHead(HttpURLConnection con) m?#J`?E  
{ ?IHa>f:  
for(int i=1;;i++) 7o5~J)qIC  
{ JK@" &  
String header=con.getHeaderFieldKey(i); ;'g.%  
if(header!=null) (D5.NB%@  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); K$(Li
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Utility.log(header+" : "+con.getHeaderField(header)); E A8>{}Z*  
else ); <Le
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break; fPLi8`r  
} _onEXrM  
} ]t|-  
1}"PLq(  
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public void splitterStop() 9?~K"+-SI  
{ s$ v<p(yl  
bStop = true; "P_PqM  
} )]~;Ac^x  
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} ELWm>'Q#9  
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/* 7w]NG`7  
**FileAccess.java -w#Hy>E  
*//文件访问(定位，写) Sd0y=!Pj=  
package NetFox; n:P5m9T  
import java.io.*; jLLZZPBK  
+S3r]D3v/  
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public class FileAccessI implements Serializable{ )Ap0" ?q  
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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 ~^u#Q\KE"  
RandomAccessFile oSavedFile; JIobs*e0m  
long nPos; x\m?*5p  
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public FileAccessI() throws IOException uI*2}Q   
{ eGJ}';O,g  
this("",0); W7ffdODb  
} 7<ZCeM2x  
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public FileAccessI(String sName,long nPos) throws IOException KASw3!.W  
{ PN&;3z Z  
oSavedFile = new RandomAccessFile(sName,"rw"); jdF~0#vH  
this.nPos = nPos; (GNY::3  
oSavedFile.seek(nPos); R#QcQx  
} WO=,NQOw  
i[wEH1jR  
;.g
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public synchronized int write(byte[] b,int nStart,int nLen) p*^[ ~}N  
{ F;&a=R!.  
int n = -1; DY~zi  
try{ ~Uet)y<  
oSavedFile.write(b,nStart,nLen); oy)'wb~  
n = nLen; Pd[&&!+gV  
} itg PG  
catch(IOException e) ,Q5Z<\  
{ *ydU3LG7  
e.printStackTrace (); D`G ;kp  
} XtV=Gr8"  
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return n; XZk?aik}`  
} jPjFp35;zb  
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} [MkXQwY  
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/* '#fwNbD  
**SiteInfoBean.java 3~%wA(|A  
*/ ?l3PDorR  
package NetFox; ,X2CV INb}  
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public class SiteInfoBean { *&\fBi]  
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private String sSiteURL; //Site's URL }gr6na
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private String sFilePath; //Saved File's Path q-;z!iq|!  
private String sFileName; //Saved File's Name iw$n*1M  
private int nSplitter; //Count of Splited Downloading File ;6?VkF  
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public SiteInfoBean() \2K_"5  
{//nSplitter的缺省值为5 BZP~m=kq  
//default value of nSplitter is 5 m'Thm{Y,?n  
this("","","",5); gUcG#  
} 9? #pqw  

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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ft"
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{ ftqi>^i  
sSiteURL= sURL; 2bB&/Uumsd  
sFilePath = sPath; wV9[Jl\Z  
sFileName = sName; Hz&.]yts2J  
this.nSplitter = nSpiltter; 2J
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} d`_X$P4y  
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public String getSSiteURL() fgg;WXcT ~  
{ /puM3ZN  
return sSiteURL; lP!`lhc-^  
} Dm"@59x  
*W#_W]Tu  
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public void setSSiteURL(String value) FE`:1  
{ jtMN)TM  
sSiteURL = value; c&Mci"nj0  
} Iaq7<$XU  
k lRS:\dW  

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public String getSFilePath() d`z),A=  
{ O=HT3gp&  
return sFilePath; BtSl%(w  
} Felu`@b  
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public void setSFilePath(String value) ~olta\|  
{ k-v@sb24_  
sFilePath = value; em87`Hj^lo  
} *uLlf'qU]  
i_? S#L]h  
O;NQJ$^bI  
public String getSFileName() 2VNMz[W'  
{ *o/Q#  
return sFileName; 0<{+M`G/  
} ]yxRaW9f  
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public void setSFileName(String value) Tn~b#-0  
{ 8h&Ed=gi  
sFileName = value; Hd1e9Q,:|  
} ;t.LLd  
8( ^;h2O!  
>taC_f06  
public int getNSplitter() )$*T>.JA  
{ o*OaYF'8  
return nSplitter; RtrESwtR  
} >k6RmN  
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public void setNSplitter(int nCount) Bu ~N)^  
{ IT3xX=|b  
nSplitter = nCount; H+]>*^'8  
} +%$'(ts  
} vGK'U*gGD  
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B rGaCja  
/* DQ{Yr>
J  
**Utility.java >f [Lb|t  
*/ 6#/Riu%  
package NetFox; L}bS"=B[&W  
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public class Utility { ,FvBZ.4c3=  
: kVEB<G  
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public Utility() MCOz-8@|Y  
{
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Rw$>()}H8  
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} >Lh+(M;+F  
F[Dhj,C"  
//线程睡眠 k!gf
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public static void sleep(int nSecond) ,[To)x5o  
{ a *n^(  
try{ N7=L^]  
Thread.sleep(nSecond); L{K:XiPn  
} {2`:7U~|  
catch(Exception e) 1M|DaAI  
{ 4s?x 8oAy  
e.printStackTrace (); -r9G5Z!|n  
} x0ZEVa0`4  
} p{knQ],   
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//日志 w l.#{@J]<  
public static void log(String sMsg) A$K>:Tt>  
{ (fc /"B-  
System.err.println(sMsg); r-#23iT.~  
} f)xHSF"  
gDP\u<2!  
^^[MDjNy@  
public static void log(int sMsg) O]OZt,k(  
{ }MKm>N  
System.err.println(sMsg); %Lec\(-4L  
} 4{Vw30DZ  
} 6e1/h@p\7  
%4:tRF  
o|\0IG(\  
/* ?QGAiu0  
**TestMethod.java aB9Pdut  
*/ ?UAB}CjY  
package NetFox; IfHB+H   
/n= %#{  
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public class TestMethod { xP<cF  
;~Eb Q  
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public TestMethod() @D!KFJ  
{ ///xx/weblogic60b2_win.exe 0ad
 -4  
try{ Jsi [,|G  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); uf;^yQi  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); $9v:(:!Bm  
SiteFileFetch fileFetch = new SiteFileFetch(bean); y6|&bJ @  
fileFetch.start(); T<*i($ [  
} ~Uw**PT3M  
catch(Exception e){e.printStackTrace ();} 6,j6,Q(67  
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} `3!ERQU  
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,Mf@I5?  
public static void main(String[] args) [gZd$9a  
{ D*d@<&Bl4<  
new TestMethod(); }-H<wQ&x  
} $QQv$  
} bd[zdL#4K  
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