http断点续传简单实现（java)

/* 9+_SG/@  
**SiteFileFetch.java ~{/"fTif  
*/ 0"3l2Eo  
package NetFox; 9Eu.Y
 
import java.io.*; h`;w/+/Zr  
import java.net.*; 1#/>[B  
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public class SiteFileFetch extends Thread { unY+/p $  
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SiteInfoBean siteInfoBean = null; //文件信息Bean iK%%  
long[] nStartPos; //开始位置 #0GvL=}k  
long[] nEndPos; //结束位置 Xt& rYv  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 AU0pJB'  
long nFileLength; //文件长度 Rw-!P>S$  
boolean bFirst = true; //是否第一次取文件 g]%sX6T  
boolean bStop = false; //停止标志 P+K< /i  
File tmpFile; //文件下载的临时信息 %PW_v~sg  
DataOutputStream output; //输出到文件的输出流 2SVBuV/R  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ,aq0Q<}~lc  
public SiteFileFetch(SiteInfoBean bean) throws IOException ^/b3_aM5d  
{ vVBu/)  
siteInfoBean = bean; ^qvN:v$1  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); aGSix}b1P  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 8=\}#F  
if(tmpFile.exists ()) dX^ ^ @7  
{ \k&2nYVHf  
bFirst = false; kn9ul3c  
read_nPos(); QmxI;l  
} ->_rSjnM{  
else /z
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{ ;=r_R!
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nStartPos = new long[bean.getNSplitter()]; p`N+9t&I4  
nEndPos = new long[bean.getNSplitter()]; fXD9w1  
} `-yo-59E[  
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} [C@|qAh  
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public void run() wX/0.aZ|  
{ lW6$v* s9  
//获得文件长度 xfegi$  
//分割文件 !:BmDX[<n  
//实例FileSplitterFetch ?5VPV9EX  
//启动FileSplitterFetch线程
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//等待子线程返回 b}<?& @  
try{ y
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if(bFirst) |tn.ZEgw3~  
{ w&F.LiX^  
nFileLength = getFileSize(); n[+$a)$8  
if(nFileLength == -1) w{+G/Ea  
{ }aSTo"~m#  
System.err.println("File Length is not known!"); 5TynAiSD_>  
} 1|bg;X9+  
else if(nFileLength == -2) <b>g^ `}?D  
{ +PAb+E|,  
System.err.println("File is not access!"); {#U3A_y  
} W!jg  
else t nvCtuaR  
{ e)BU6m%  
for(int i=0;i<nStartPos.length;i++) ~S\y)l\wZ  
{ 6>DmcG:.  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 2UbTKN  
} M1HGXdN*B  
for(int i=0;i<nEndPos.length-1;i++) #EG$HX]  
{ wa1Qt  
nEndPos = nStartPos[i+1]; ka=EOiX.  
} 9@3cz_[J  
nEndPos[nEndPos.length-1] = nFileLength; %r =9,IJ  
} 0^('hS&  
} omu)s '8  
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//启动子线程 15J t @{<r  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; vCX
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for(int i=0;i<nStartPos.length;i++) "rVf{
  
{ X:2)C-l?  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), &9OnN<mT1  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), jCp^CNbA  
nStartPos,nEndPos,i); 2QIx~Er  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); nVyV]'-z  
fileSplitterFetch.start(); nG4}8  
} ,II-:&H  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), `=%mU/v  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); i K,^|Q8  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ]iezwz`'  
nEndPos = " + nFileLength); \p.eY)>  
// fileSplitterFetch[nPos.length-1].start(); G
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//等待子线程结束 \%/Y(YVm  
//int count = 0; XlJA}^e  
//是否结束while循环 Um%$TGw5  
boolean breakWhile = false; 1c4@qQyo  
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while(!bStop) b}HwvS:  
{ 01w}8a(  
write_nPos(); 4{6XZ_J1  
Utility.sleep(500); wX+KW0|>  
breakWhile = true; jJqq:.XqB8  
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for(int i=0;i<nStartPos.length;i++) @:w[(K[^b/  
{ hqc)Ydg_%  
if(!fileSplitterFetch.bDownOver) |C`.m
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{ H^fErl  
breakWhile = false; \AY*x=PF  
break; #-7w|  
} 6 K-jje;)  
} 8~|tl,  
if(breakWhile) 'U*Kb  
break; Y]neTX [ef  
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//count++; uRnSwJ"hE  
//if(count>4) ?#gYu%7DN  
// siteStop(); 6b-E|;"]:^  
} "w&G1
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+`&-xq76  
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System.err.println("文件下载结束！"); pxV@fH+`  
} Z(c2F]  
catch(Exception e){e.printStackTrace ();} ~{$5JIpCm  
}  2p;N|V  
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//获得文件长度 3:MAdh[w  
public long getFileSize() Dssecc'  
{ BvqypLI  
int nFileLength = -1; k.6(Q_TS  
try{ i1^#TC$x  
URL url = new URL(siteInfoBean.getSSiteURL()); QLD
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); glUf.:]  
httpConnection.setRequestProperty("User-Agent","NetFox"); eb=#{  
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int responseCode=httpConnection.getResponseCode(); q~6((pWi|  
if(responseCode>=400) :\69N/uw`  
{ rvETt  
processErrorCode(responseCode); JAU:Wqlg1  
return -2; //-2 represent access is error bR}=bp4K  
} f0ME$:2  
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String sHeader; `kM:5f+>W  
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for(int i=1;;i++) "PfNC<MQo  
{ dU.H9\p  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); =*=qleC3  
//Utility.log(in.readLine()); ~T:L0||.%9  
sHeader=httpConnection.getHeaderFieldKey(i); fBZR  
if(sHeader!=null) A5kz(pj  
{ 'D[g{LkL  
if(sHeader.equals("Content-Length")) CAtdx!  
{ Y N*"q'Yz_  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Hq."_i{I  
break; -iySU 6  
} vJfj1 f  
} pa2cM%48  
else 2>h.K/pC  
break; n+H);Dg<8  
} DcX,o*ec!  
} B`/p

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catch(IOException e){e.printStackTrace ();} ,#hx%$f}d  
catch(Exception e){e.printStackTrace ();} BiI`oCX  
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Utility.log(nFileLength); L%5g]=  
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return nFileLength; _su$]s  
} ]`u_d}`  
#9u2LK  
!fK9YW(Im  
//保存下载信息（文件指针位置） OE[N$,4I*  
private void write_nPos() D.Z4noMA6  
{ xyPz_9  
try{ C?fa-i0l^  
output = new DataOutputStream(new FileOutputStream(tmpFile)); xSL%1>MrN  
output.writeInt(nStartPos.length); lbnH|;`$]m  
for(int i=0;i<nStartPos.length;i++) G !;
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{ +X4/l"|  
// output.writeLong(nPos); v|#}LQZ  
output.writeLong(fileSplitterFetch.nStartPos); Ika(ip#]=  
output.writeLong(fileSplitterFetch.nEndPos); !F[^?:pK  
} Yxd&hr  
output.close(); 6R';[um?q  
} d'*:2;)g^  
catch(IOException e){e.printStackTrace ();} a_amO<!   
catch(Exception e){e.printStackTrace ();} p}9bZKyf  
} Ai5|N
 
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//读取保存的下载信息（文件指针位置） 25m!Bf  
private void read_nPos() > ?<C+ZHh  
{ WJF#+)P:Y  
try{ k+`e0Jago  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); .F@0`*#rE~  
int nCount = input.readInt(); CI~ll=9`  
nStartPos = new long[nCount]; WbH#@]+DN  
nEndPos = new long[nCount]; #b5V/)K  
for(int i=0;i<nStartPos.length;i++) ~E*`+kD  
{ .E&-gXJ4  
nStartPos = input.readLong(); ?h7(,39^>  
nEndPos = input.readLong(); `&!J6)OJ  
} JsyLWv@6xa  
input.close(); %:vMD  
} QX>Pni  
catch(IOException e){e.printStackTrace ();} mQqv{1  
catch(Exception e){e.printStackTrace ();} u
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} 6%t>T~x  
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private void processErrorCode(int nErrorCode) zD%@3NA4
1  
{ 2m0laJ3p9  
System.err.println("Error Code : " + nErrorCode); I'>r  
} $pGdGV\H  
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//停止文件下载 t-3y`31i.  
public void siteStop() k.("<)  
{ *9I/h~I  
bStop = true; TaTs-]4  
for(int i=0;i<nStartPos.length;i++) kZJ.G  
fileSplitterFetch.splitterStop(); )ND%MYJSq  
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< rqFBq8  
} l4smAT  
} ExJexjOWI^  
//负责部分文件的抓取 ~.L\f%<  
**FileSplitterFetch.java WC *e#QP  
*/ '980.  
package NetFox; NB[(O#  
L-QzC<[F/  
;!H|0sv  
import java.io.*; 6im!v<1Qx  
import java.net.*; ~T'Ri=  
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public class FileSplitterFetch extends Thread { M^3pJ=;5  
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String sURL; //File URL eSlZAdK  
long nStartPos; //File Snippet Start Position C=uYX"  
long nEndPos; //File Snippet End Position `am]&0g^+(  
int nThreadID; //Thread's ID s
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boolean bDownOver = false; //Downing is over *oca  
boolean bStop = false; //Stop identical "Acc]CqH*  
FileAccessI fileAccessI = null; //File Access interface 7GVI={
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException u[;,~eB%w  
{ **!  
this.sURL = sURL; Gn7P` t*.  
this.nStartPos = nStart; mpysnKH  
this.nEndPos = nEnd; = gbB)u-Pc  
nThreadID = id; xQK;3b  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 9/_F  
} 1?j['~aE  
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public void run() 3sy|pa  
{ Sp>v`{F  
while(nStartPos < nEndPos && !bStop) / Hg/)  
{ M)v4>Rw+  
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try{ *sbZ{{]e  
URL url = new URL(sURL); ;%_s4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); F:B8J4/  
httpConnection.setRequestProperty("User-Agent","NetFox"); P/
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String sProperty = "bytes="+nStartPos+"-"; @fz!]/  
httpConnection.setRequestProperty("RANGE",sProperty); qPI1\!z6  
Utility.log(sProperty); h.ln%6:d  
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InputStream input = httpConnection.getInputStream(); 3j2#'Jf|:  
//logResponseHead(httpConnection); K,'v{wSr  
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byte[] b = new byte[1024]; /-v6jiM  
int nRead; UBZ37P  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) eK)R=M@i  
{ G!L(K  
nStartPos += fileAccessI.write(b,0,nRead); Spqbr@j  
//if(nThreadID == 1) Gi=s|vt  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ]dj W^C]94  
} CfMCc:8mL  
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Utility.log("Thread " + nThreadID + " is over!"); X
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bDownOver = true; l1?$quM^V  
//nPos = fileAccessI.write (b,0,nRead); _hz}I>G@B  
} *@1(!A  
catch(Exception e){e.printStackTrace ();} AIU=56+I\  
} xxS>O%  
} YooPHeQ  
}\$CU N  
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//打印回应的头信息 d(X/N2~g  
public void logResponseHead(HttpURLConnection con) I)YUGA5  
{ cKM#0dq  
for(int i=1;;i++) YQ7\99tj  
{ F
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String header=con.getHeaderFieldKey(i); gL(_!mcwu  
if(header!=null) 49?wEm#  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); rY,zZR+@  
Utility.log(header+" : "+con.getHeaderField(header)); S8Ec.]T  
else !+(c/ gwBh  
break; p`I[3/$3  
} V=cJdF  
} $c0<I59&|  
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public void splitterStop() 49iqrP'  
{ aT_%G&.  
bStop = true; w}WfQj  
} =v:}{~M^$  
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} vBLs88  
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/* B{hV|2  
**FileAccess.java 4o69t  
*//文件访问(定位，写) <To$Hb,NP  
package NetFox; ]]eI80u[  
import java.io.*; f>zd,|)At  
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public class FileAccessI implements Serializable{ @=NTr  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 qF3s&WI  
RandomAccessFile oSavedFile; wvcj*{7[  
long nPos; >Hwf/Gf[  
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public FileAccessI() throws IOException u/.# zn@9h  
{ ZU68\cL  
this("",0); 8O| w(z  
} =v(&qh9Q2  
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public FileAccessI(String sName,long nPos) throws IOException OD6dMql  
{ 9yYNX;C  
oSavedFile = new RandomAccessFile(sName,"rw"); AK//]   
this.nPos = nPos; a^eR~efdu@  
oSavedFile.seek(nPos); ">v-CSHY  
} 9WT{~PGj  
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9ePR6WS4  
public synchronized int write(byte[] b,int nStart,int nLen) r*kz`cJ  
{ ^~kfo|  
int n = -1; 9|l6.$Me/  
try{ d04fj/B  
oSavedFile.write(b,nStart,nLen); UWW'[gEP1  
n = nLen; ;-quK%VO!  
} Z\S'HNU  
catch(IOException e) #Fckev4  
{ B,4 3b O  
e.printStackTrace (); /}Ct2w&<k  
} Q;k D Jo  
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return n; $VJE&b  
} "\O{!Hj8  
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} c?}{>ig/)  
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/* "Z#MR`;&29  
**SiteInfoBean.java $qk(yzY  
*/ qj<_*  
package NetFox; |^t8ct?x~  
*_tJ;  
k1_3\JO"6  
public class SiteInfoBean { #3((f[  
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private String sSiteURL; //Site's URL LE@`TPg$R  
private String sFilePath; //Saved File's Path QiQO>r  
private String sFileName; //Saved File's Name 'fIirGOl  
private int nSplitter; //Count of Splited Downloading File WHvxBd  
e]u3[ao  
QVQ?a&HYS  
public SiteInfoBean() q/^&si  
{//nSplitter的缺省值为5 APY*SeIV  
//default value of nSplitter is 5
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this("","","",5); -,}ppTG  
} Xw<Nnvz6  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 9 e0Oj3!B  
{ ompkDl\E  
sSiteURL= sURL; \&5t@sC  
sFilePath = sPath; s(M8 Y  
sFileName = sName; x)!NB99(tC  
this.nSplitter = nSpiltter; s9b 6l,Z  
\F8*HPM=*  
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} tJ@5E^'4  
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public String getSSiteURL() PH3#\ v.   
{ 9|RR;k[  
return sSiteURL; $.-\2;U  
} 1U< g  
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public void setSSiteURL(String value) m\?H <o0  
{ Jp]eFaqp  
sSiteURL = value; Ee-yP[2 *  
} '}$$o1R  
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public String getSFilePath() %#,EqN  
{ ?\
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return sFilePath; #Jqa_$\.  
} o `N /w  
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public void setSFilePath(String value) %wuD4PRK  
{ ]EZiPW-uy  
sFilePath = value; MUfhk)"  
} @>sZ'M2mq  
1O,<JrE+-  
V,qc[*_3  
public String getSFileName() mh=YrDU+L  
{ 2RC|u?+@  
return sFileName; 8RJ^e[?o(  
} NLA/XZ  
W6 U**ir.  
[:(
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public void setSFileName(String value) ~E tW B  
{ QBI;aG<+b>  
sFileName = value; BHa'`lCb  
} j6_
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public int getNSplitter() $06[D91'  
{ lEe<!B$d"  
return nSplitter; +__PT4ps  
} ^<VJ8jk<  
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public void setNSplitter(int nCount) n$O[yRMI[  
{ hPB^|#}  
nSplitter = nCount; <//#0r*  
} d1rIU6  
} F$k^px  
NP#:} )  
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/* uVn"'p-  
**Utility.java = olmBXn/  
*/ j
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package NetFox; R]! [h  
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public class Utility { 7(S66  
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$ rU"Krf67  
public Utility() %HAforH  
{ V6IC
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8$TSQ~  
} ;qN;oSK  
KW1b #g%Z  
//线程睡眠 x[_SNX"  
public static void sleep(int nSecond) O;dtz\  
{ 'fIoN%  
try{ 0lm7'H*~  
Thread.sleep(nSecond); H-|%\9&{S  
} z?DI4O#Up  
catch(Exception e) ^.HvuG},O  
{ OkV*,n  
e.printStackTrace (); 3Hd~mfO\  
} &{uj3s&C   
} nign"r  
4
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//日志 \QvoL  
public static void log(String sMsg) wJ%;\06  
{ {)?:d6"  
System.err.println(sMsg); 9k.5'#  
} };Oyv7D+b  
f
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x,% %^(  
public static void log(int sMsg) a7@':Rb n  
{ LN0pC}F  
System.err.println(sMsg); /L yoTBG  
} BtA_1RO  
} Rl/5eE8  
5w+KIHhN|  
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/* 31^
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**TestMethod.java qC x|}5:  
*/ Kt#_Ln_6  
package NetFox; M(/ATOJ(  
<%iRa$i5  
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public class TestMethod { S T1V  
QHDR*tB:{  
]T:a&DHC  
public TestMethod() b$;qtfJG  
{ ///xx/weblogic60b2_win.exe _@5|r|P>  
try{ vk0b b3){D  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 1)o6jGQ  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); >'1h  
SiteFileFetch fileFetch = new SiteFileFetch(bean); }] p9  
fileFetch.start(); Fc6o6GyL|o  
} S6CI+W  
catch(Exception e){e.printStackTrace ();} -^aJ}[uaI  
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?:$\ t?e^  
} , UsY0YC  
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public static void main(String[] args) {MV,>T_  
{ ?Qxf~,F  
new TestMethod(); HSk_'g(\0  
} U EjP
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} lz7?Z  
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