http断点续传简单实现（java)

/* mIo7 K5z{  
**SiteFileFetch.java wCmv/m  
*/ jtY~-@*  
package NetFox; VAt9JE;#  
import java.io.*;  O+j:L  
import java.net.*; :n9^:srGZH  
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~ }22Dvo  
public class SiteFileFetch extends Thread { wm71,R1  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ;#j82  
long[] nStartPos; //开始位置 ]l%.X7M9  
long[] nEndPos; //结束位置 j@!}r|-T  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 -rlX<(pl)  
long nFileLength; //文件长度 -`EoTXT*U  
boolean bFirst = true; //是否第一次取文件 cvfAa#tq>  
boolean bStop = false; //停止标志 e8bJ]  
File tmpFile; //文件下载的临时信息 dR:iUw:V  
DataOutputStream output; //输出到文件的输出流 V+z)B+  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） &N0|tn  
public SiteFileFetch(SiteInfoBean bean) throws IOException v2sU$M  
{ a6P.Zf7  
siteInfoBean = bean; 7`!( 8  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); qKC*jDW  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); NkI:
  
if(tmpFile.exists ()) $:wM'&M  
{ 1}*;  
bFirst = false; jRAL(r|  
read_nPos(); 0g-ESf``{n  
} q(Q9FonU  
else +r_[Tj|Er  
{ ,+.# eg  
nStartPos = new long[bean.getNSplitter()]; J}CK|}  
nEndPos = new long[bean.getNSplitter()]; au*jMcq  
} 7!;/w;C  
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} V0i$"|F+E  
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public void run() & jvG]>CS'  
{ KL]!E ~i  
//获得文件长度 'bPo 5V
|  
//分割文件 RC%r7K f  
//实例FileSplitterFetch v19`7qgR(  
//启动FileSplitterFetch线程 2zu~#qU[)M  
//等待子线程返回 d 4R+gIA  
try{ e~?]F0/  
if(bFirst) uD5yw#`  
{ wP?q5r5  
nFileLength = getFileSize(); |0p'p$%  
if(nFileLength == -1) cyg>hX{U  
{ yTiqG5r  
System.err.println("File Length is not known!"); g1,  
} Uiw7Y\Im|  
else if(nFileLength == -2) :X*LlN  
{ i{qURP}.  
System.err.println("File is not access!"); /GGu` f  
} YU(*kC8   
else o#/iR]3  
{ V}+;bbUc-  
for(int i=0;i<nStartPos.length;i++) Y'1V(5/&  
{ yG$@!*|  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); :PkZ(WZ9  
} FoCkTp+/  
for(int i=0;i<nEndPos.length-1;i++) %$| k3[4V  
{ ZRGZ'+hw  
nEndPos = nStartPos[i+1]; 7!wnx.  
} #HYkzjb  
nEndPos[nEndPos.length-1] = nFileLength; ?GU!ke p  
} %nF\tVP3]  
} XtdLKYET  
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//启动子线程 C
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; o1+]6s+j}  
for(int i=0;i<nStartPos.length;i++) ZH_4'm!^g|  
{ :exuTn  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ',Pk>f]AB-  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), x~tQYK   
nStartPos,nEndPos,i); % 6.jh#C  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Z"Ni Y  
fileSplitterFetch.start(); i]%"s_l  
} olxP`iK  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Nn1^#kc  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); RGI6W{\  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", F6VIH(  
nEndPos = " + nFileLength); \ZZy`/~z*7  
// fileSplitterFetch[nPos.length-1].start(); rd4'y~#S  
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=XlIe{  
//等待子线程结束 gi@ji-10  
//int count = 0; -wMW@:M_  
//是否结束while循环 b)^ZiRW``  
boolean breakWhile = false; u?Mu*r?  
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while(!bStop) ?4Juw?  
{ 2_b'mepV  
write_nPos(); ~(^*?(Z  
Utility.sleep(500); G>>u#>0  
breakWhile = true; u@u.N2H
.%  
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for(int i=0;i<nStartPos.length;i++) }h h^U^ia  
{ [=3tAPpzK  
if(!fileSplitterFetch.bDownOver) pF+wHMhUe  
{ +J8/,d  
breakWhile = false; 9$@ g;?}Ps  
break; ~c$ts&Cl  
} C?|3\@7  
} ~9
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if(breakWhile) [c[MQA0  
break; |ZlT>u  
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]pTw]SK  
//count++; /Py>HzRE:  
//if(count>4) |hQ|'VCN  
// siteStop(); Sb4PCt  
} qpqz. {\  
7qK0!fk5  
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System.err.println("文件下载结束！"); f.)F8!!  
} Cy:`pYxhd  
catch(Exception e){e.printStackTrace ();} <;E[)tv  
} m{dyVE  
(jMAa%
  
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//获得文件长度 E816YS='  
public long getFileSize() ?iEXFYJG  
{ dN/ "1%9)  
int nFileLength = -1; l~!fQ$~  
try{ C!k9JAa$Z  
URL url = new URL(siteInfoBean.getSSiteURL()); rnv7L^9^A  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); b\j&!_   
httpConnection.setRequestProperty("User-Agent","NetFox"); L(2P|{C  
VN-#R=D  
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int responseCode=httpConnection.getResponseCode(); 3]OP9!\6  
if(responseCode>=400) BI.k On=  
{ D6)Cjc>a  
processErrorCode(responseCode); S*m`'  
return -2; //-2 represent access is error ^~<Rzq!  
} RzJ}CT  
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qTh='~m4[  
String sHeader; ka)LK@p6  
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for(int i=1;;i++) K[>@'P}y  
{ UtBlP+bE?y  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); lH@
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//Utility.log(in.readLine()); }A)
36  
sHeader=httpConnection.getHeaderFieldKey(i); 0Q- Mxcj  
if(sHeader!=null) ENx@Ex
 
{ UQ.D!q  
if(sHeader.equals("Content-Length")) [q+e]kD  
{ H@2"ove-uC  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); j_'rhEdLP  
break; @f5@0A\0  
} Lr?4Y  
} t-7[Mk9@  
else eMl]td rI  
break; E?gu(\an@  
} L+~YCat|$U  
} cv*Q]F1%  
catch(IOException e){e.printStackTrace ();} jFNs=D&(  
catch(Exception e){e.printStackTrace ();} Q^MXiEO+  
"^ 6lvZP(  
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Utility.log(nFileLength); j #I:6yA3  
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return nFileLength; <[y$D=n  
} $]H=  
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//保存下载信息（文件指针位置） bxhg*A  
private void write_nPos() 2
^ ,H_PS  
{ <{NYD.  
try{ ',H$
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output = new DataOutputStream(new FileOutputStream(tmpFile)); 42J';\)oP  
output.writeInt(nStartPos.length); 1ntkM?  
for(int i=0;i<nStartPos.length;i++) P7wqZ?  
{ Rg?{?qK\K  
// output.writeLong(nPos); MB8SB   
output.writeLong(fileSplitterFetch.nStartPos); #NN"(I  
output.writeLong(fileSplitterFetch.nEndPos); G V:$;  
} EAD0<I<>  
output.close(); u3*NO )O  
} $vTAF-~Ql  
catch(IOException e){e.printStackTrace ();} $\,BpZ }3  
catch(Exception e){e.printStackTrace ();} W`Q$t56  
} b$goF }b'g  
,u&tB|,W,  
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//读取保存的下载信息（文件指针位置） X<Th{kM2  
private void read_nPos() T}tE/  
{ o4/I1Mq  
try{ 'ybth
 
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); $W/+nmb)@K  
int nCount = input.readInt(); ."IJmv  
nStartPos = new long[nCount]; aVQSN  
nEndPos = new long[nCount]; xI@$aTGq  
for(int i=0;i<nStartPos.length;i++) 0
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{ GDHK.?GY  
nStartPos = input.readLong(); YA"Ti9-EV  
nEndPos = input.readLong(); %kK ][2e  
} 5PGlR!^  
input.close(); dSe8vA!)  
} r:c@17  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();} SE;Tujwhqi  
} {K45~ha9!m  
#*Yi4Cn<  
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private void processErrorCode(int nErrorCode) $!|8g`Tm  
{ jD'  
System.err.println("Error Code : " + nErrorCode); kqKj7L  
} lh\ICN\O  
#+K
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)D["M$ZA^  
//停止文件下载 af<NMgT2s~  
public void siteStop() IpWy)B>Fl3  
{ j{{~ZM  
bStop = true; t['k%c  
for(int i=0;i<nStartPos.length;i++) 'dIX=/RZ  
fileSplitterFetch.splitterStop(); v[{8G^Z}54  
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} *L%6qxl`V  
} %RQC9!  
//负责部分文件的抓取 x">W u2  
**FileSplitterFetch.java eVw\v#gd  
*/ [j)\v^m  
package NetFox; .M9d*qp`S  
}+91s'/c  
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import java.io.*; TL},Unq  
import java.net.*; PIZ C;K4|  
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public class FileSplitterFetch extends Thread { `Yx-~y5X  
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String sURL; //File URL q2x|%HRF  
long nStartPos; //File Snippet Start Position  4%g6_KB  
long nEndPos; //File Snippet End Position AbUDn\0$  
int nThreadID; //Thread's ID )7&42>t  
boolean bDownOver = false; //Downing is over {&2$[g=[ ^  
boolean bStop = false; //Stop identical uY^v"cw/F  
FileAccessI fileAccessI = null; //File Access interface _:35d1[  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException "?apgx 6  
{ j5L)N  
this.sURL = sURL; T4OguP=  
this.nStartPos = nStart; tg.|$n  
this.nEndPos = nEnd; %55@3)V8Rf  
nThreadID = id; <eB<^ &nd  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 _W)`cr  
} $_Y/'IN`k  
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public void run() hi!L\yi  
{ Y,k(#=wg  
while(nStartPos < nEndPos && !bStop) A2m_q>> !  
{ ^"3\iA:  
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try{ s%eyW _  
URL url = new URL(sURL); 0B=[80K;8  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); aSc{Ft/O  
httpConnection.setRequestProperty("User-Agent","NetFox"); 9YR]
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String sProperty = "bytes="+nStartPos+"-"; $o]r]#B+  
httpConnection.setRequestProperty("RANGE",sProperty); 8g\wVKkTQp  
Utility.log(sProperty); &J8Z@^  
b,nn&B5@{  
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InputStream input = httpConnection.getInputStream(); q`XW5VV{K  
//logResponseHead(httpConnection); 7FAIew\r  
lB1#  
24#bMt#^  
byte[] b = new byte[1024]; !Citzor  
int nRead; Ls&+XlrX8  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) JkZ50L  
{ 25UYOK}!  
nStartPos += fileAccessI.write(b,0,nRead); _eGT2,D5r  
//if(nThreadID == 1) rkkU"l$v  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); led))qd@V-  
} z"tjDP  
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Utility.log("Thread " + nThreadID + " is over!"); <"W?<VjO  
bDownOver = true; [+;qWfs B  
//nPos = fileAccessI.write (b,0,nRead); ))!Bg?t-  
} #Mh{<gk%ax  
catch(Exception e){e.printStackTrace ();} X*i/A<Y`=  
} / /'Tck  
} :z]}ZZ  
?AEd(_a!q  
-;^;2#](g  
//打印回应的头信息 nSS>\$  
public void logResponseHead(HttpURLConnection con) P` #QGZ>  
{ [r(Qs|  
for(int i=1;;i++) r#A_RZ2~@  
{ 7KU~(?|:h  
String header=con.getHeaderFieldKey(i); /RGNAHtIi  
if(header!=null) @}WNKS&m  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); "< v\M85&  
Utility.log(header+" : "+con.getHeaderField(header)); ] /+D^6  
else %?bcT[|3  
break; u_PuqRcs  
} 0n.S,3|  
} P.djd$#  
QdQd(4/1  
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public void splitterStop() 'Gjq/L/x  
{ &rp!%]+xAM  
bStop = true; RPVT*`o  
} P"1 S$oc  
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#Z\
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} Cp#)wxi6[y  
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/* I^D0<lHl~  
**FileAccess.java w1r$='*I  
*//文件访问(定位，写) 'CXRG$
D  
package NetFox; %K(0W8&  
import java.io.*; p~2UUmV  
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public class FileAccessI implements Serializable{ !Vheq3"q/  
k6!4Zz_8  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 (DDyK[t+VX  
RandomAccessFile oSavedFile; *XbI#L%>  
long nPos; w(j^ccPD  
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public FileAccessI() throws IOException N L'R\R  
{ Gs dnf 7  
this("",0); Rrg8{DZhv  
} *f5l=lDOB  
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?
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public FileAccessI(String sName,long nPos) throws IOException '9s5OTkN ;  
{ w5KPB5/zu  
oSavedFile = new RandomAccessFile(sName,"rw"); BByCMY  
this.nPos = nPos; .R5y:O  
oSavedFile.seek(nPos); 99=s4*xzM  
} R^*K6Ad  

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cu&,J#r%  
public synchronized int write(byte[] b,int nStart,int nLen) ar.AL
'  
{ kS :\Oz\  
int n = -1; aRJcSV  
try{ Jq ]:<TQ  
oSavedFile.write(b,nStart,nLen); ZDx@^P y  
n = nLen; hXn3,3f3oZ  
} YE}s  
catch(IOException e) TZRcd~5$  
{ nmFC%p)4  
e.printStackTrace (); 06*rWu9P3  
} `zpbnxOL$T  
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g~S)aU\:,  
return n; %."@Q$lA  
} N^w'Hw0  
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} ,xI%A, (,;  
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!@A#=(4R4  
/* Y+~g\z-]c  
**SiteInfoBean.java x9W(cKB'S  
*/ /mM2M-  
package NetFox; O 5Nb  
}(XdB:C8  
kJQ#Wz|z]  
public class SiteInfoBean { j'0r'  
?7MqeR4/E  
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private String sSiteURL; //Site's URL &~e$:8+  
private String sFilePath; //Saved File's Path 27F~(!n  
private String sFileName; //Saved File's Name Yw;D:Y(  
private int nSplitter; //Count of Splited Downloading File 5 BtX63  
_-~`03 `!  
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public SiteInfoBean() BV`-=wRC  
{//nSplitter的缺省值为5 a4i:|
  
//default value of nSplitter is 5 5S{7En~zUE  
this("","","",5); X"fh@.  
} [&?8,Q(  
w$Ot{i|$(  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) (Y%Q|u  
{ qT:zEt5  
sSiteURL= sURL; \C^;k%{LV  
sFilePath = sPath; ra N)8w}-  
sFileName = sName; qmy%J  
this.nSplitter = nSpiltter; 1xE]6he4{T  
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} #-% A[7Cdp  
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public String getSSiteURL() _ee dBpV  
{ 7Q w|!  
return sSiteURL; 6x)$Dl  
} !R-z%  
s@hRqGd:  
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public void setSSiteURL(String value) '_k+WH&  
{ :!a2]-D}  
sSiteURL = value; '})0!g<Y  
} P|tNL}2`;  
`+:.L>5([  
!HeSOzN  
public String getSFilePath() ^u}L;`L  
{  7R#+Le)  
return sFilePath; _p-t<ytnh  
} vsWHk7 9  
hN2:d1f0  
wkqX^i7ls  
public void setSFilePath(String value) Cv ejb+  
{ ?Iyo9&1&  
sFilePath = value; )}vNOE?X~  
} ps .]N   
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public String getSFileName() mGUO6>g  
{ OA/WtQ5  
return sFileName; |tR
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} v:Tzv^  
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public void setSFileName(String value) 4'4\,o  
{ iy.2A!f^.  
sFileName = value; ,lA.C%4au~  
} P}ok*{"J<>  
!zj0/QG\  
/xGmg`g<#  
public int getNSplitter() ~c)~015`  
{ ^<e@uNGg  
return nSplitter; mC?i}+4>4R  
} K{b(J Nd  
;zM*bWh9  
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public void setNSplitter(int nCount) wn_b[tdxq  
{ x8\A<(G_M=  
nSplitter = nCount; PHA-9\jC{  
} o9xlu.QL{c  
} w.,Q1\*rPp  
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:1t~[-h^  
/* O=SkAsim  
**Utility.java ZxV"(\$n  
*/ .s+aZwTMT  
package NetFox; Y]]}*8  
pwwH<0[  
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public class Utility { 1+-_s  
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public Utility() 9j W2  
{ qd"_Wu6aF=  
!T]
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J!'@Bd  
} {hln?'  
AU-n&uX  
//线程睡眠 "qc6=:y}  
public static void sleep(int nSecond) .9md~j:o^s  
{ nhIa175'  
try{ kJWN.  
Thread.sleep(nSecond); #Z6'?p9  
} +f*OliMD  
catch(Exception e) ^c:Fy+fb  
{ meN2ZB?Y  
e.printStackTrace (); "D?z  
} z]b>VpW:  
} `tjH<  
*tm0R>?!  
//日志 JXyM\}9-X  
public static void log(String sMsg) Ag F,aZU  
{ JQ4{` =,b  
System.err.println(sMsg); gTA%uRBa  
} dnV[ P  

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Or !+._3i  
public static void log(int sMsg) hXqD<?  
{ V& C/Z}\  
System.err.println(sMsg); u%~igt@x  
} uV 7BK+[O  
} GnP|x}YM  
s21wxu:  
J|&JD?  
/* rvr-XGK36\  
**TestMethod.java R+&jD;U{
 
*/ !Hys3AP  
package NetFox; x\Z'
2?u}  
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public class TestMethod { TLoz)&@  
kOh{l: 2-+  
:n /@z4#  
public TestMethod() |&Ym@Jyj  
{ ///xx/weblogic60b2_win.exe pv&y9
1  
try{ B<C*  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); KiJT!moB  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); O(+phRwJ  
SiteFileFetch fileFetch = new SiteFileFetch(bean); }:Z#}8  
fileFetch.start(); H,N)4;F<c  
} wm+/e#'&  
catch(Exception e){e.printStackTrace ();} ?_I[,N?@41  
NJNJjdD>  
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} eds26(  
#>j.$2G>  
XoA+MuDzpo  
public static void main(String[] args) ,=l7:n  
{ tU_y6  
new TestMethod(); 2(/g}  
} i+gQE!  
}
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