http断点续传简单实现（java)

/* HDIB GG~  
**SiteFileFetch.java R<Ojaj=V  
*/ H;k
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package NetFox; QN9$n%Z  
import java.io.*; l:a+o gm3  
import java.net.*;  LS,/EGJ  
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public class SiteFileFetch extends Thread { ik+qx~+`Qv  
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SiteInfoBean siteInfoBean = null; //文件信息Bean -9~kp'_a  
long[] nStartPos; //开始位置 L5
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long[] nEndPos; //结束位置 '
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 Nm--h$G  
long nFileLength; //文件长度 _J6|ju\  
boolean bFirst = true; //是否第一次取文件 HelC_%#^  
boolean bStop = false; //停止标志 3%/]y=rA  
File tmpFile; //文件下载的临时信息 .6!IO^`[  
DataOutputStream output; //输出到文件的输出流 r) T^ Td1  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） VQZ3&]o  
public SiteFileFetch(SiteInfoBean bean) throws IOException F8;M+
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{ GfUIF]X  
siteInfoBean = bean; (sW:^0p  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ;DL|%-%;$r  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); b,Ed}Ir  
if(tmpFile.exists ()) n&iWYECz  
{ P!,\V\TY]  
bFirst = false; *DLv$/(0  
read_nPos(); p>Ju)o  
} '&W`x5`t  
else <]b}R;9v  
{ CM>/b3nOW  
nStartPos = new long[bean.getNSplitter()]; Dj
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nEndPos = new long[bean.getNSplitter()];  @zEEX9U  
} Y$--Hp4  
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} n>Y3hY  
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public void run() HW|c -\t
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{ !aeL*`;  
//获得文件长度 UG s <<  
//分割文件 I.fV_ H^  
//实例FileSplitterFetch ibl^A=  
//启动FileSplitterFetch线程 RecA?-0  
//等待子线程返回 O4@Ki4f3A%  
try{ -DlKFN  
if(bFirst) NS#qein~i  
{ %;!@\5$  
nFileLength = getFileSize(); zG[fPD  
if(nFileLength == -1) doBfpQ2  
{ S6$S%$  
System.err.println("File Length is not known!"); y+(<Is0w  
} r[eZV"  
else if(nFileLength == -2) k*-_CO-h  
{ 8d-; ;V  
System.err.println("File is not access!"); 25l
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} +>.plvZhu  
else G#HbiVH9  
{ H.7gSB1  
for(int i=0;i<nStartPos.length;i++) ?Gp~i]  
{ L4zSro:Si  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ldM [8  
} Oe'Nn250  
for(int i=0;i<nEndPos.length-1;i++) w^ui%9 &6H  
{ 0Q;T <%U  
nEndPos = nStartPos[i+1]; )*G3q/l1u6  
} ~B:Lai4"  
nEndPos[nEndPos.length-1] = nFileLength; DvG.G+mo#  
} req=w;E:  
} ?f1%)]>   
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//启动子线程 [NFg9y;{h  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Ve2z= 6(  
for(int i=0;i<nStartPos.length;i++) ,YSQog  
{ k1L GT&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), }Tu_?b`RUm  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), n #p6i  
nStartPos,nEndPos,i); bFVz ;  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 9|v  
fileSplitterFetch.start(); s.6S:  
} 8doT`rI1  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), :
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); .Y&_k  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 7WiVor$g-  
nEndPos = " + nFileLength); 6](vnS;  
// fileSplitterFetch[nPos.length-1].start(); itm;,Sbg  
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//等待子线程结束 mppBc-#EYr  
//int count = 0; Ufv{6"sH  
//是否结束while循环 xii*"n
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boolean breakWhile = false; Q~,E K  
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while(!bStop) Nk3]<#$  
{ $P^=QN5Bb  
write_nPos(); Xr:"8FT  
Utility.sleep(500); Y3-Tg~/~W  
breakWhile = true; eoR@5OA&  
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for(int i=0;i<nStartPos.length;i++) N,(@k[uta  
{ |E53 [:p  
if(!fileSplitterFetch.bDownOver) !H~!i.m'-  
{ lDe9EJR  
breakWhile = false; 2N5N^S  
break; Cs^o- g!L  
} HNY{%D  
} '$ s:cS`=  
if(breakWhile) (dpBGt@  
break; L0UAS'hf  
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//count++; ,T|iA/c
 
//if(count>4) 3Nr8H.u&q  
// siteStop(); *gMuo6  
} Xvi{A]V  
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,$}P<WZMu  
System.err.println("文件下载结束！"); \z:p"eua z  
} m]Z+u e  
catch(Exception e){e.printStackTrace ();} &'WgBjP  
} *#N%3:@T  
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6:v8J1G(<  
//获得文件长度 OA%.>^yb@  
public long getFileSize() ?TMo6SU  
{ t82Bp[t  
int nFileLength = -1; i2N*3X~  
try{ Lg9]kpOpa  
URL url = new URL(siteInfoBean.getSSiteURL()); s<E_74q1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); I}n"6'*  
httpConnection.setRequestProperty("User-Agent","NetFox"); b7aAP*$  
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int responseCode=httpConnection.getResponseCode(); *%B%BJnX  
if(responseCode>=400) { zlq6z  
{ ^nkwT~Bya  
processErrorCode(responseCode); m
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return -2; //-2 represent access is error 6jCg7Su]  
} sFSrMI#R  
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String sHeader; ~i))Zc3,g\  
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for(int i=1;;i++) *fSa8CV  
{ }mu8fm'  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); dam.D.o"  
//Utility.log(in.readLine()); U!3nn#!yE  
sHeader=httpConnection.getHeaderFieldKey(i); 6XFO@c}d  
if(sHeader!=null) dMRwQejY{7  
{ CrS[FM= +W  
if(sHeader.equals("Content-Length")) 1?7QS\`)fB  
{ d`({
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); *'d5~dz=  
break; IdzF<>;W  
} %m+ZrH(  
} h=`rZC  
else lba*&j]w=  
break; j|lg&kN  
} eC[g"Ef  
} *$`r)pV%AK  
catch(IOException e){e.printStackTrace ();} 168U-<  
catch(Exception e){e.printStackTrace ();} qaw5<
 
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Utility.log(nFileLength); Q{>9Dg  
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return nFileLength; /%)MlG  
} SB$~Btr  
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V X211U.Q  
//保存下载信息（文件指针位置） KgAc0pz{7H  
private void write_nPos() AuO%F YKY  
{ 07/5RFmJ  
try{ dr'6N1B@  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ?ZTB u[  
output.writeInt(nStartPos.length); &hV;3";  
for(int i=0;i<nStartPos.length;i++) `f6Qd2\  
{ `e`4
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// output.writeLong(nPos); -z'@Mh|i6l  
output.writeLong(fileSplitterFetch.nStartPos); vaTXu*   
output.writeLong(fileSplitterFetch.nEndPos); M$! 0ikh  
} 1$".7}M4$  
output.close(); qn+mlduU  
} 35&&*$Jm  
catch(IOException e){e.printStackTrace ();} lFc3 5  
catch(Exception e){e.printStackTrace ();} }
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} m#8}!u&  
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K
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//读取保存的下载信息（文件指针位置） I,  
private void read_nPos() !Y\hF|[z  
{ QL|Vke:N4  
try{ w`!Yr:dU  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); _`D760q}  
int nCount = input.readInt(); ef!I |.FW  
nStartPos = new long[nCount]; 2{U4wTu  
nEndPos = new long[nCount]; N3x}YHFF  
for(int i=0;i<nStartPos.length;i++) W_iP/xL  
{ rWbL_1Eq  
nStartPos = input.readLong(); ?I7H ):  
nEndPos = input.readLong(); SxOM@A  
} 3FX`dZ  
input.close(); N>]u;HjH  
} ]'M4Unu#@  
catch(IOException e){e.printStackTrace ();} W@UHqHr:\  
catch(Exception e){e.printStackTrace ();} ]}'WNy6c&x  
} EEkO[J[=  
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private void processErrorCode(int nErrorCode) NugJjd56x  
{ L`Qiu@  
System.err.println("Error Code : " + nErrorCode); Y61E|:fV!  
} F." L{g  
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//停止文件下载 #m8Oy|Y9`  
public void siteStop() .(`u'G=  
{ #p_ ~L4iW  
bStop = true; >!a*wf~]  
for(int i=0;i<nStartPos.length;i++) K0+J!-a]7  
fileSplitterFetch.splitterStop(); 8eLNKgc  
):.]4n{L  
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} .6/[X`*  
} VF[]E0=u6  
//负责部分文件的抓取 !PQ@"L)p  
**FileSplitterFetch.java nY~CAo/:  
*/ <Ft.{aNq$c  
package NetFox; ,l@hhaLm?  
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import java.io.*; z6Mf>q  
import java.net.*; $ Q2|{*  
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public class FileSplitterFetch extends Thread { F]~`57  
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String sURL; //File URL bfrBHW#  
long nStartPos; //File Snippet Start Position D.\p
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long nEndPos; //File Snippet End Position q@^=im  
int nThreadID; //Thread's ID e|{6^g<ru  
boolean bDownOver = false; //Downing is over Xw![}L>  
boolean bStop = false; //Stop identical 7H./o Vl  
FileAccessI fileAccessI = null; //File Access interface 6lZhV[~Z/  

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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException zIm$S/Qe*  
{ `FmI?:Cv  
this.sURL = sURL; 6BMRl%3>Z  
this.nStartPos = nStart; P/ug
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this.nEndPos = nEnd; A\ LTAp(I  
nThreadID = id; Ct.Q)p-wn  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 -M(:z  
} &d6'$h:kHb  
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public void run() rb,&i1  
{ *8MU,6  
while(nStartPos < nEndPos && !bStop) b$M? _<G  
{ ogQbST  
4}=]QQoE  
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try{ RL
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URL url = new URL(sURL); Uu3[Cf=C  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); u2BVQ<SA  
httpConnection.setRequestProperty("User-Agent","NetFox"); B8C"i%8V)  
String sProperty = "bytes="+nStartPos+"-"; ZpWG  
httpConnection.setRequestProperty("RANGE",sProperty); X,gXgxP\  
Utility.log(sProperty); j@ =n|cq  
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InputStream input = httpConnection.getInputStream(); C96|T>bk  
//logResponseHead(httpConnection);
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byte[] b = new byte[1024]; JQ0KXS Nr  
int nRead; 0HF",:yl  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) LQR9S/?Ld  
{ FIW*Nr  
nStartPos += fileAccessI.write(b,0,nRead); dGHRHXi  
//if(nThreadID == 1) YSeXCJ:Iy  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8)M .W  
} ^i@tOtS  
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Utility.log("Thread " + nThreadID + " is over!"); N/^r9Nu  
bDownOver = true; -a/5  
//nPos = fileAccessI.write (b,0,nRead); }`*]&I[P  
} y"P$:l  
catch(Exception e){e.printStackTrace ();} Kb{  
} L2Mcs  
} 9[8?'`m  
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//打印回应的头信息 8Zwq:lV Q  
public void logResponseHead(HttpURLConnection con) dG6Mo76  
{ Mi:$<fEX  
for(int i=1;;i++) [NH[n#  
{ q.rnZU  
String header=con.getHeaderFieldKey(i); O/0m|~`iY  
if(header!=null) + PGfQN  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 4Mnne'7  
Utility.log(header+" : "+con.getHeaderField(header)); J]Uki*s  
else '{Iv?gh"  
break; g+)T\_#u  
} 54tpR6%3p  
} N}zQ)]xz+r  
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public void splitterStop() uKhfZSx0w  
{ JCS$Tm6y<_  
bStop = true; Vb0hlJb  
} OTalR;:]r  
 27w]Q_C  
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} He&dVP  
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/* mltN$b%G=d  
**FileAccess.java oIX]9~  
*//文件访问(定位，写) t'FY*|xk  
package NetFox; eK4\v:oG1  
import java.io.*; fWF\V[  
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public class FileAccessI implements Serializable{ TzerAX^  
uFG]8pj2V1  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 3'*SSZmnOB  
RandomAccessFile oSavedFile; m9xO& @#vx  
long nPos; (<2PhJ|  
+KXg&A/^  
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public FileAccessI() throws IOException " c}pY^(  
{ %6dFACv  
this("",0); StaX~J6=  
} c7
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public FileAccessI(String sName,long nPos) throws IOException  +'Tr>2V  
{ JdFMSmZ@  
oSavedFile = new RandomAccessFile(sName,"rw"); u;;]S!:M  
this.nPos = nPos; ~Ui<y=d  
oSavedFile.seek(nPos); =Tb~CT
=  
} ?$ o9/9w  
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public synchronized int write(byte[] b,int nStart,int nLen) }-YD_Pm K-  
{ 5\RKT)%X  
int n = -1; pA4oy  
try{ SJj0*ry:  
oSavedFile.write(b,nStart,nLen); )O2giVq7[0  
n = nLen; CzST~*lH  
} A)s  
catch(IOException e) om9fg66  
{ pH'#v]"  
e.printStackTrace (); ep>S$a*|  
} U!^\DocAY  
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return n; jsfyNl?6  
} w/E4wp  
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} Xn9TQ"[4  
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/* _U%!&_m6  
**SiteInfoBean.java >jRz4%  
*/ mEr*n  
package NetFox; ub0]nov  
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public class SiteInfoBean { ko$bCG%  
9bq#&~+  
!+=jD3HTJ  
private String sSiteURL; //Site's URL ?4(uwXp  
private String sFilePath; //Saved File's Path a[[u>oHyd  
private String sFileName; //Saved File's Name <eI7xifD  
private int nSplitter; //Count of Splited Downloading File f-tjMa /_  
%'%r.  
h 5t,5e}  
public SiteInfoBean() `lqMifD  
{//nSplitter的缺省值为5 <s)+V6\E  
//default value of nSplitter is 5 FsTE.PT  
this("","","",5); qun#z$  
} $xa#+  
7V%}U5  
3[pA:Z+xx  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 2BsMFMIw1  
{  #/MUiV  
sSiteURL= sURL; 8s6[?=nM  
sFilePath = sPath; o_vK4%y(  
sFileName = sName; srw5&s(3X  
this.nSplitter = nSpiltter; <dLdSEw  
+\?#8U
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} n!~{4 uUW  
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public String getSSiteURL() IM7k\  
{ 0bzD-K4WVd  
return sSiteURL; -r_z,h|  
} 5E+l5M*(  
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public void setSSiteURL(String value) VSc;}LH  
{ B=JeZMn  
sSiteURL = value; `7LN?- T  
} 4?jXbC k~x  
{~.h;'m  
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public String getSFilePath() sX^m1v~N|  
{ RYZh"1S;k  
return sFilePath; pMHY2t  
} V+W,#5  
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public void setSFilePath(String value) #(?EL@5  
{ 8Tyf#`'I  
sFilePath = value; K!lGo3n]  
} A=Q"IdK  
/9/=]  
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public String getSFileName() @D[jUC$E  
{ t.v@\[{-  
return sFileName; S6*3."Sk  
} DO'$J9;*  
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public void setSFileName(String value) 5#!pwjt~7  
{ -e3m!h  
sFileName = value; >}\!'3)_  
} 5Y"JRWC  
hp/}Z"A=  
#6[FGM  
public int getNSplitter() & ;ie+/B  
{ q*SX.A>YR  
return nSplitter; ,ic.b @u1  
} )wQR2$x~  
~^2Y*|{)  
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public void setNSplitter(int nCount) }b~;x6  
{ MW=2GhD=  
nSplitter = nCount; \(R(S!xr_  
} DI'wZy
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} Ratg!l|'-  
8j. 9Sk/  
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/* Mf^ ;('~  
**Utility.java wLAGe'GX  
*/ /0>Cy\eN0  
package NetFox; Y.Na9&-(  
L&+XFntR  
d}GO(  
public class Utility { yk5-@qo  
4nzUDeI3MG  
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public Utility() )zkk%mE/IM  
{ <v&>&;>3  
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}rz}>((ZHF  
} 7Co 
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{aqceg  
//线程睡眠 ( ?3 )l  
public static void sleep(int nSecond) [~,~ e  
{ y&")7y/uE  
try{ J 6U3}SO=y  
Thread.sleep(nSecond); u* G|TF  
} ev7Y^   
catch(Exception e) |_{-hNiz0  
{ y,v*jE  
e.printStackTrace (); Lj6$?(x}  
} <?
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} bm*Ell\a.  
C s?kZ %  
//日志 i=#<0!m  
public static void log(String sMsg) 'Pk ( 1:  
{ }:P/eY  
System.err.println(sMsg); !run3ip`Z  
} |Tuk9d4]  
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rIR~YMv!  
public static void log(int sMsg) R@-rc|FunJ  
{ m{gx\a.5  
System.err.println(sMsg); % zHsh  
} -bd
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} WBL
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SE&J)Sj]  
/*
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**TestMethod.java k)oD  
*/ hVo]fD|W  
package NetFox; %?1k}(qUeY  
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fFudoIC  
public class TestMethod { ,d'x]&a  
7Rqjf6kX`O  
s|.V:%9e  
public TestMethod() N1`/~Gi  
{ ///xx/weblogic60b2_win.exe H]K(`)y}4  
try{ Q"n|<!DN  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); (E )@@p7,:  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); xH#R_  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 9IZ}}x  
fileFetch.start(); UmZ#Cm  
} ig3HPlC  
catch(Exception e){e.printStackTrace ();} Vi[* a  
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} A q;]al  
3QM6M9M  
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public static void main(String[] args) 9#L0Q%,*  
{ 9E~=/Q=  
new TestMethod(); #u`i4  
} (9$z+Zmm?  
} *U|K~dl]K  
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