http断点续传简单实现（java)

/* A\jX#gg  
**SiteFileFetch.java (\QkXrK  
*/ f
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package NetFox; W\tSXM-Hg  
import java.io.*; $1h,<$5H  
import java.net.*; Y!8Ik(/~i  
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public class SiteFileFetch extends Thread { H ',Nt  
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SiteInfoBean siteInfoBean = null; //文件信息Bean w1je|Oil  
long[] nStartPos; //开始位置 `~bnshUk  
long[] nEndPos; //结束位置 2^}E!(<  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 =vv4;az X  
long nFileLength; //文件长度 y3 R+060\3  
boolean bFirst = true; //是否第一次取文件 L;7x2&  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 @@,
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DataOutputStream output; //输出到文件的输出流 7>a-`"`O  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） c:/H}2/C  
public SiteFileFetch(SiteInfoBean bean) throws IOException bk**% ]  
{ =c-,uW11[  
siteInfoBean = bean; 1?6;Oc^  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); [HKTXF{n  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); i 
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if(tmpFile.exists ()) <4gT8kQ$x  
{ [ET03 nZ  
bFirst = false; ;BsPms@U  
read_nPos(); >&|C E2'  
} _7AR2  
else MVGznf?  
{ 5/:BtlFx  
nStartPos = new long[bean.getNSplitter()]; rI\G&OqpP  
nEndPos = new long[bean.getNSplitter()]; 6dRxfbL  
} 6w d0"  
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} ;'.[h*u~<  
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public void run() 6iiH+Nc  
{ -/>SdR$D7  
//获得文件长度 =kp-[7  
//分割文件 O<0G\sU  
//实例FileSplitterFetch z9k3@\7  
//启动FileSplitterFetch线程 Z\{"/( Hi  
//等待子线程返回 Ut;,Z  
try{ `wJR^O!e  
if(bFirst) 6]=R#d 7U  
{ +Mb;;hb  
nFileLength = getFileSize(); uY,(3x  
if(nFileLength == -1) -I$qe Xy  
{ 6gLk?^.  
System.err.println("File Length is not known!"); $nB4Ie!WcR  
} y{.s 4NT  
else if(nFileLength == -2) %<|w:z$vp  
{ -.8 nEO3  
System.err.println("File is not access!"); mCa[?  
} YxEc(a"  
else K5O#BBX=  
{ zFy0SzF  
for(int i=0;i<nStartPos.length;i++) t;7 tuq   
{ (p2jigP7a[  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); XY[uyR4Z  
} e12.suv  
for(int i=0;i<nEndPos.length-1;i++) yG
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{ zj ;'0Zu  
nEndPos = nStartPos[i+1]; vJheM*C  
} H\OV7=8  
nEndPos[nEndPos.length-1] = nFileLength; [ 7W@/qqv  
} gK{-eS  
} ^f:oKKaAW;  
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//启动子线程 !
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; - J9K  
for(int i=0;i<nStartPos.length;i++) 1 m)WM,L  
{ JG%y_ Qy?K  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), '%@fW
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), UN7>c0B  
nStartPos,nEndPos,i); "r6DZi(^K  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); wI!>IV(5  
fileSplitterFetch.start(); ?U~9d"2=  
} ;(cqaB  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #$&!)13  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); l.ri]e  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", |[ymNG  
nEndPos = " + nFileLength); *_ 2db  
// fileSplitterFetch[nPos.length-1].start(); -6(u09mb_  
-r%3"C=m  
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//等待子线程结束 E2M|b  
//int count = 0; 86c@Kk7z  
//是否结束while循环 :wn9bCom?M  
boolean breakWhile = false; f%Y'7~9bA  
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while(!bStop) ={[
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{ f;<qGM.#|  
write_nPos(); 4{?Djnh  
Utility.sleep(500); 3g!tk9InG  
breakWhile = true; UADD 7d  
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for(int i=0;i<nStartPos.length;i++) }%K)R5C  
{ =-XI)JV#  
if(!fileSplitterFetch.bDownOver) 3jMHe~.E<  
{ ')kn  
breakWhile = false; o1x IGP<  
break; Tw|cgB  
} 3<ikMUq&  
} Ob:}@jj  
if(breakWhile) N/ 7Q(^  
break; (1`z16  
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`N8?F3>
 
//count++; C-Q]f
 
//if(count>4) >7yOu!l  
// siteStop(); YGRv``(  
} D^+#RR'#,  
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System.err.println("文件下载结束！"); Tx)X\&ij&  
} %d<uOCf\Q  
catch(Exception e){e.printStackTrace ();} u{F^Ngy )  
} F!FXZht$P  
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//获得文件长度 N# o" W  
public long getFileSize() %#!pAUP\&  
{ F9DY\EI  
int nFileLength = -1; >'>onAIL  
try{ 8cqH0{  
URL url = new URL(siteInfoBean.getSSiteURL()); Z^AOV:|m  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); q.s2x0  
httpConnection.setRequestProperty("User-Agent","NetFox"); ~f/nq/8  
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int responseCode=httpConnection.getResponseCode(); |P{K\;-  
if(responseCode>=400) A^/$|@  
{ 4CR.=  
processErrorCode(responseCode); {0J TN%e  
return -2; //-2 represent access is error ,2H@xji [  
} :JBvCyj4PE  
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String sHeader; !+qy~h  
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for(int i=1;;i++) Ku6bY|  
{ ?.&]4z([  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); >Ux5UD  
//Utility.log(in.readLine()); m'|{AjH z6  
sHeader=httpConnection.getHeaderFieldKey(i); U#=Q`  
if(sHeader!=null) $vlc@]~d`&  
{ _wa1R+`_  
if(sHeader.equals("Content-Length")) H{Zfbb  
{ $tGk,.#j  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); C
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break; x.Sq2rw]V  
} oz!;sj{,D  
} R)s@2S  
else <S*o}:iB  
break; JgI+k Nx  
} 'g<0MOq{  
} seT?:PCA  
catch(IOException e){e.printStackTrace ();} &"^,Ubfcn"  
catch(Exception e){e.printStackTrace ();} m"MTw@}SJ;  
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Utility.log(nFileLength); -"u9s[L{  
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return nFileLength; %<x2=#0  
} /\=syl  
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//保存下载信息（文件指针位置） X{SD3j=G#  
private void write_nPos() /b*VFA/75  
{ P{ AJH1  
try{ 2jQ|4$9j  
output = new DataOutputStream(new FileOutputStream(tmpFile)); (+'*_   
output.writeInt(nStartPos.length); iV8j(HV  
for(int i=0;i<nStartPos.length;i++)  * A B  
{ J%ym1A9  
// output.writeLong(nPos); dpHK~n j\_  
output.writeLong(fileSplitterFetch.nStartPos); W~ 6ii\  
output.writeLong(fileSplitterFetch.nEndPos); MV"aO@  
} HtWuZq;w  
output.close(); n:c)R8X]  
} y}NBJ  
catch(IOException e){e.printStackTrace ();} O=wA/T=w?  
catch(Exception e){e.printStackTrace ();} vM5u]u!  
}
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//读取保存的下载信息（文件指针位置） -\mbrbG9H  
private void read_nPos() wIi_d6?  
{ 2=pVX  
try{ ,(0q  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); cC'{+j8-a  
int nCount = input.readInt(); ?zwPF;L
*  
nStartPos = new long[nCount]; KNtsz[#b  
nEndPos = new long[nCount]; nK*$P +[R  
for(int i=0;i<nStartPos.length;i++) \M4/?<g  
{ psb$rbu7[  
nStartPos = input.readLong(); 8 Zy`Z   
nEndPos = input.readLong(); ^+CTv  
} }]cKOv2  
input.close(); `>^2MHF3LT  
} )L?JH?$C  
catch(IOException e){e.printStackTrace ();} W(N@`^  
catch(Exception e){e.printStackTrace ();} ZJz6{cY  
} (;^VdiJ  
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private void processErrorCode(int nErrorCode) V!=1 !"}OG  
{ $j(2M?.>#  
System.err.println("Error Code : " + nErrorCode); g%1
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} #S+GI!  
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//停止文件下载 0m?v@K' l  
public void siteStop() Vw7NLTE}`  
{ C!N&uNp@s  
bStop = true; '+tU8Pb  
for(int i=0;i<nStartPos.length;i++) {5}UP@h  
fileSplitterFetch.splitterStop(); n,eO6X 4  
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} v@bs4E46e  
} r0=Aru5n  
//负责部分文件的抓取 T9enyYt%  
**FileSplitterFetch.java \]  
*/ 1=C>S2q  
package NetFox; 7o?6Pv%HJC  
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import java.io.*; WZ}c)r*R  
import java.net.*; "7_6iB&@<  
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public class FileSplitterFetch extends Thread { <'H^}gQow  
#&vP(4p  
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String sURL; //File URL S[!-M\b  
long nStartPos; //File Snippet Start Position VIo %((  
long nEndPos; //File Snippet End Position Lc;4 Hg  
int nThreadID; //Thread's ID mVGQyX  
boolean bDownOver = false; //Downing is over =VkbymIZ4y  
boolean bStop = false; //Stop identical @A(*&PU>j  
FileAccessI fileAccessI = null; //File Access interface V[>MKB(  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException <\]o#w*:  
{ xcO Si>  
this.sURL = sURL; m_~!Lj[u.  
this.nStartPos = nStart; :Mr_/t2(  
this.nEndPos = nEnd; xk=5q|u_-  
nThreadID = id; yRaB\'  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 T1ZAw'6(K  
} b!VaEK  
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public void run() MH|!tkW>:  
{ )24r^21.q  
while(nStartPos < nEndPos && !bStop) `mV&[`NZ  
{ +5(
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try{ |<&9_Aq_  
URL url = new URL(sURL); [>xwwm  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2<Lnfc<^k  
httpConnection.setRequestProperty("User-Agent","NetFox"); 3A2X1V"  
String sProperty = "bytes="+nStartPos+"-"; |- 39ZZOX  
httpConnection.setRequestProperty("RANGE",sProperty); qX[a\HQa  
Utility.log(sProperty); ]v7f9MC'\  
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InputStream input = httpConnection.getInputStream(); ?<c)r~9]  
//logResponseHead(httpConnection); } y@pAeS,  
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byte[] b = new byte[1024]; h32QEz-+  
int nRead; CqQ>"Y  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) R%
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{ l@vaupg  
nStartPos += fileAccessI.write(b,0,nRead); 3# G;uWN-  
//if(nThreadID == 1) 4R-Y9:^t  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ]Ga}+^  
} 8/X#thG  
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Utility.log("Thread " + nThreadID + " is over!"); fMRBGcg7Dc  
bDownOver = true; dD@k{5  
//nPos = fileAccessI.write (b,0,nRead); *Q=ER  
} 6tXx--Nh  
catch(Exception e){e.printStackTrace ();} jt-Cy  
} P]A>"-k  
} -?gr3rV@  
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//打印回应的头信息 nsWenf  
public void logResponseHead(HttpURLConnection con) Z_{`$nW  
{ 1qXqQA  
for(int i=1;;i++) lquY_lrri  
{ ^Nl)ocHv!  
String header=con.getHeaderFieldKey(i); FWqnlK#  
if(header!=null) 7g1"s1~or  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); cwiHHf>  
Utility.log(header+" : "+con.getHeaderField(header)); &!uw;|%  
else Htn'(Q  
break; '6Dt@^-PZ  
} p.,o@GcL~  
} qUX  
$ )ps~  

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public void splitterStop() %''z~LzJ8  
{ MJsz  
bStop = true; d
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} o, e y.  
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} e _\]Q-  
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/* =/wAk0c^y  
**FileAccess.java i1RU5IRy|j  
*//文件访问(定位，写) tX)l$oRPr  
package NetFox; *oLAO/)n  
import java.io.*; sdP% Y<eAT  
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public class FileAccessI implements Serializable{ \,jrug<C$^  
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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 T;D`=p#  
RandomAccessFile oSavedFile; $P#Cf&R  
long nPos; Wlm%W>%  
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public FileAccessI() throws IOException UBoN}iR  
{ $r%m<Uc;}O  
this("",0); '~i;g.n=}-  
} n|`L>@aw,  
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public FileAccessI(String sName,long nPos) throws IOException g`~c|bx  
{ lN94 b3_W  
oSavedFile = new RandomAccessFile(sName,"rw"); f&=y\uP]  
this.nPos = nPos; OMG.64DX .  
oSavedFile.seek(nPos); p-n_ ">7  
} Pk444_"=  
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public synchronized int write(byte[] b,int nStart,int nLen) o"D`_ER  
{ DArEIt6Q  
int n = -1; [OJ@{{U%  
try{ m)4s4P57y  
oSavedFile.write(b,nStart,nLen); AnVj '3  
n = nLen; jG=*\lK6  
} A[L+
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catch(IOException e) pC,MiV$c"  
{ "-JJ6Bk  
e.printStackTrace (); pnin;;D*  
} \zA$|) x  
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return n; hl}@ha4'  
} .QX|:]|n  
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} v|acKux=t  
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/* b}'XDw   
**SiteInfoBean.java  Qj(q)!Ku  
*/ "'p;Udt/Qm  
package NetFox; oj*5m+:>a  
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public class SiteInfoBean { ^SnGcr|a'  
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private String sSiteURL; //Site's URL #mY*H^jI]~  
private String sFilePath; //Saved File's Path UP=0>jjbn:  
private String sFileName; //Saved File's Name @2Xw17[f35  
private int nSplitter; //Count of Splited Downloading File Wj2]1A  
^G'8!!ys  
qH'T~#S  
public SiteInfoBean() a>A29*q  
{//nSplitter的缺省值为5 S)Cd1`Gf  
//default value of nSplitter is 5 B:qH7`s  
this("","","",5); HrQBzS  
} shjbb  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) [su2kOX|X  
{ %!$ua_8  
sSiteURL= sURL; 4eapR|#T  
sFilePath = sPath; [f["9(:  
sFileName = sName; N'_,
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this.nSplitter = nSpiltter; A,-UW+:  
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} aWhhq@  
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public String getSSiteURL() %lPAq  
{ b0PqP<{t  
return sSiteURL; tcOgF:  
} F VW&&ft  
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public void setSSiteURL(String value) j|3p.Cy
 
{ TS+itU62  
sSiteURL = value; z7'3d7r?  
} B4AV ubMbe  
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public String getSFilePath() qPsf
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{ YCod\}
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return sFilePath; >0kn&pe7#T  
} y7aBF13Kl  
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public void setSFilePath(String value) TJ9JIxnS  
{ I3uS?c  
sFilePath = value; dr3
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} 5{cbcuG  
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public String getSFileName() 1~\YJEsb}d  
{ 
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return sFileName; *(~7H6  
} 9%aBW7@SK  
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zr%2oFeX,  
public void setSFileName(String value) In)8AK(Hw  
{ }MBxfZ4I  
sFileName = value; dcUaZfON  
} Pe[~kog,TP  
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public int getNSplitter() ^(7<L<H  
{ y]$%>N0vLX  
return nSplitter; B|E4(,]^  
} U{(B)dFTH  

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public void setNSplitter(int nCount) ^eke,,~  
{ L+y}hb r
 
nSplitter = nCount; &P'cf|KI  
} (VeX[*}I  
} b 'p0T1K(  
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/* Htd-E^/
 
**Utility.java KhK:%1po  
*/ Gkci_A*  
package NetFox; sd|5oz)  
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public class Utility { >jxo,xz  
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public Utility() {RFpTh7f:  
{ %5<uQc9  
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} ktX\{g!U  
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//线程睡眠 _7df(+.{<A  
public static void sleep(int nSecond) Tjba@^T  
{ 7=yV8.cD  
try{ Zd$a}~4~  
Thread.sleep(nSecond); ,h1 z8.wD|  
} *@6,Sr)_  
catch(Exception e) )/VhkSXbG!  
{ fLM5L_S}Y  
e.printStackTrace (); :u$nH9kwv  
} n/$1&
x1  
} S8-3Nv'  
<1i:Z*l.  
//日志 r(=
 
public static void log(String sMsg) nn'a`N  
{ !,8jB(
 
System.err.println(sMsg); }pk)\^/w/  
} [-}LEH1[p  
' lt5|  
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public static void log(int sMsg) ]o}g~Xn  
{ :
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System.err.println(sMsg); epw*Px  
} 8nCw1  
} ^5j+O.zgN  
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CJ+/j=i;~c  
/* iZsZSW \  
**TestMethod.java (bpO>4(S  
*/ SM%N]/@U  
package NetFox; 7wKN  
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public class TestMethod { (I(?oCQ  
6&jW.G8/  
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public TestMethod() 7.V'T=@x3)  
{ ///xx/weblogic60b2_win.exe o< )"\f/,  
try{ SrlTwcD  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); &>Zm gz  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); aMaICM  
SiteFileFetch fileFetch = new SiteFileFetch(bean); @E Srj[  
fileFetch.start(); aU&p7y4C@  
} 3$<u3Zi6  
catch(Exception e){e.printStackTrace ();}  UZJ^e$N  
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} qUNK Dt  
}le}Vuy\s  
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public static void main(String[] args) e:W]B)0/e  
{ )Z4i

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new TestMethod(); ylFoYROO  
} 4oxAC; L  
} ^,W;d
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