http断点续传简单实现（java)

/* ^wHMKC  
**SiteFileFetch.java &l.^UQ   
*/ U!'l
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package NetFox; $-y+97  
import java.io.*; ;z?XT\C$  
import java.net.*; IQ_0[  
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public class SiteFileFetch extends Thread { F>M$|Sc2  
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SiteInfoBean siteInfoBean = null; //文件信息Bean zZxP= c  
long[] nStartPos; //开始位置 T'V(%\w  
long[] nEndPos; //结束位置 ke%zp-2c
 
FileSplitterFetch[] fileSplitterFetch; //子线程对象 X1-s,[j'  
long nFileLength; //文件长度 ?yz%r`;r  
boolean bFirst = true; //是否第一次取文件 \w:u&6,0O  
boolean bStop = false; //停止标志 qYh,No5\;t  
File tmpFile; //文件下载的临时信息 j@ "`!uPz  
DataOutputStream output; //输出到文件的输出流 RpXQi*c0  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） EK'&S=]  
public SiteFileFetch(SiteInfoBean bean) throws IOException e%P;Jj476  
{ ky#6M? \  
siteInfoBean = bean; K c<z;
 
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); w0IB8GdF  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); `%Ghtm*  
if(tmpFile.exists ()) MT5A%|He
 
{ epL[PL}  
bFirst = false; xo%iL  
read_nPos(); PHXP1)^}S  
} t2:c@)  
else
v Y\O=TZT  
{ |x4yPYBL  
nStartPos = new long[bean.getNSplitter()]; P=@lkF!\#  
nEndPos = new long[bean.getNSplitter()]; w(U/(C7R  
} Q.XsY.{  
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} vraU&ze\1  
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public void run() v;Dcq  
{ U
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//获得文件长度 NQJqS?^W&M  
//分割文件 p^:Lj9Qax  
//实例FileSplitterFetch [w/t  
//启动FileSplitterFetch线程 J*Hn/m  
//等待子线程返回 EVL;"   
try{ /$z@_U[L  
if(bFirst) ##_Za6/n  
{ C]H <L#)ZU  
nFileLength = getFileSize(); v6VhXV6$|  
if(nFileLength == -1) of`]LU:  
{ "6dbRo5%  
System.err.println("File Length is not known!"); `Y;gMrp  
} @e,Zmx  
else if(nFileLength == -2) O}-7 V5  
{ _PbfFY #  
System.err.println("File is not access!"); Mh|`XO.5I  
} Sg$\ab$  
else T/;hIX:R  
{ &-:yn&f7  
for(int i=0;i<nStartPos.length;i++) l{U3;  
{ ~K96y$ DTE  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); )R@gnTe  
} DxgT]F%  
for(int i=0;i<nEndPos.length-1;i++) gk1S"H  
{ orHD3T%&  
nEndPos = nStartPos[i+1]; WS/+Yl  
} %`1vIr(7  
nEndPos[nEndPos.length-1] = nFileLength; =)YYx8
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} 'lk74qU$  
} ss{=::#  
P` F'Nf2U  
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//启动子线程 sri#L+I  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; $0SZlq>En  
for(int i=0;i<nStartPos.length;i++) ebe@.ZVSi  
{ -l@W)?$  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), mJ>99:W+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), (VAL.v*  
nStartPos,nEndPos,i); j2 ^T:q[  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); l&Ghs@>Kl  
fileSplitterFetch.start(); Vk_&W.~  
} t)Q@sKT6  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ('-}"3  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ?1:/ 6  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", SQU%N  
nEndPos = " + nFileLength); =k=2~ j  
// fileSplitterFetch[nPos.length-1].start(); YiuOu(X  
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%`'z^W  
//等待子线程结束 r)]CZ])  
//int count = 0; |Du13i4].&  
//是否结束while循环 ,M&0<k\  
boolean breakWhile = false; Ti|++oC/&  
_1> 4Q%  
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while(!bStop) fsc~$^.~\  
{ xO-U]%oq  
write_nPos(); +7<>x-+  
Utility.sleep(500); ]MLLr'6?  
breakWhile = true; y6Epi|8  
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for(int i=0;i<nStartPos.length;i++) m'(;uR`  
{ >X,A
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if(!fileSplitterFetch.bDownOver) fEG3b#t N  
{ ;3}EBcw)  
breakWhile = false; H L|spl(c  
break; ?
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} d3G{0PX  
} "E|r3cN  
if(breakWhile) )R)$T'  
break; 1R%`i'$/  
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9>&tMq  
//count++; QcG5PV  
//if(count>4) XVDd1#h  
// siteStop(); tP Efz+1N  
} hJo^Wo  
L^Q+Q)zTh  
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System.err.println("文件下载结束！"); #f3;}1(  
} BZ;}ROmqk  
catch(Exception e){e.printStackTrace ();} Ym.l@(  
} Rs F3#H  
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NC.P2^%  
//获得文件长度 '<&EPUO  
public long getFileSize() -)OkG#J@  
{ B.mbKntK)R  
int nFileLength = -1; ]6BmCh  
try{ *Qg5Z   
URL url = new URL(siteInfoBean.getSSiteURL()); ZE8/ 
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); f;Bfh3  
httpConnection.setRequestProperty("User-Agent","NetFox"); .eabtGO,  
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int responseCode=httpConnection.getResponseCode(); ,M@m4bx  
if(responseCode>=400) _:gGD8  
{ RCh$j&Tn  
processErrorCode(responseCode); =,d* {m~A  
return -2; //-2 represent access is error Y%)h)El  
} w38c  
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String sHeader; ?z@v3(b[  
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for(int i=1;;i++) S#h'\/S  
{ T018)WrhL  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); c BHL,  
//Utility.log(in.readLine()); \)otu\3/  
sHeader=httpConnection.getHeaderFieldKey(i); uRm_  
if(sHeader!=null) K=c=/`E  
{ c8-69hb?  
if(sHeader.equals("Content-Length")) sWsG,v_  
{ -eR!qy:.]5  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); DrCWvpudd  
break; 5X`w&(]m  
} +f X}O9  
} jom}_  
else GS
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break; hC|5e|S  
} [%7;f|p?  
} /lr1hW~Dbk  
catch(IOException e){e.printStackTrace ();} K_AtU/  
catch(Exception e){e.printStackTrace ();} 8<yV  
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Utility.log(nFileLength); T/GgF&i3  
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return nFileLength; 8tLT'2+H#  
} {=bg5I0|a  
i
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//保存下载信息（文件指针位置） HPtTv}l  
private void write_nPos() "Ju/[#VCJ  
{ GUu\dl9WA'  
try{ ~?AC:  
output = new DataOutputStream(new FileOutputStream(tmpFile)); R3B5-^s
 
output.writeInt(nStartPos.length); `26V`%bPkr  
for(int i=0;i<nStartPos.length;i++) YY#s=  
{ G2CZwm{/f  
// output.writeLong(nPos); Uz6{>OCvk|  
output.writeLong(fileSplitterFetch.nStartPos); x|@1wQ"6  
output.writeLong(fileSplitterFetch.nEndPos); y+4?U  
} }BI~am_  
output.close(); Wl& >6./{  
} <XQN;{xSa  
catch(IOException e){e.printStackTrace ();} {{V;:+62  
catch(Exception e){e.printStackTrace ();} });cX$  
} .
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//读取保存的下载信息（文件指针位置） y|q@;*rGNa  
private void read_nPos() bz,Da  
{ O.@g/05C  
try{ ,wtFs!8  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); {S5RK-ax  
int nCount = input.readInt(); L6|Hgrj-u  
nStartPos = new long[nCount]; pN\)(:"8v  
nEndPos = new long[nCount]; 9W{,=.%MX$  
for(int i=0;i<nStartPos.length;i++) CfPXn0I  
{ RLdlz  
nStartPos = input.readLong(); )KSisEL  
nEndPos = input.readLong(); oL
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}
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input.close(); Op`I;Q #%d  
} W(;x\Nc7  
catch(IOException e){e.printStackTrace ();} zKIGWH=qqm  
catch(Exception e){e.printStackTrace ();} !oZQ2z~  
} %04:z77  
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private void processErrorCode(int nErrorCode) D:=t*2-Iv  
{ ^cYStMjpy  
System.err.println("Error Code : " + nErrorCode); h&)fu{   
} <Z{vC  
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8)L'rW{q#  
//停止文件下载 EzR%w*F>Q  
public void siteStop() R[x7QlA;  
{ {eEBrJJeB  
bStop = true; To3^L_v"
 
for(int i=0;i<nStartPos.length;i++) 3>RcWy;1i  
fileSplitterFetch.splitterStop(); iI3v[S  
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} FX H0PK  
} QB!jLlg(  
//负责部分文件的抓取 PeO]lq  
**FileSplitterFetch.java 'S =sj}X  
*/ 1TKEm9j]u  
package NetFox; $aB/+,  
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import java.io.*; d; 9*l!CF  
import java.net.*; iJFr4o/R  
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public class FileSplitterFetch extends Thread { z)}3**3'y  
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\ jECSV|  
String sURL; //File URL ^;.T}c%N  
long nStartPos; //File Snippet Start Position 4w'lu"U  
long nEndPos; //File Snippet End Position 8EOh0gk7  
int nThreadID; //Thread's ID GxxDY]!  
boolean bDownOver = false; //Downing is over N? M   
boolean bStop = false; //Stop identical b`$yqi<[  
FileAccessI fileAccessI = null; //File Access interface lK0s=4c{  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException J0=7'@(p  
{ |~z3U>  
this.sURL = sURL; Odm#wL~E  
this.nStartPos = nStart; xdPcsox~  
this.nEndPos = nEnd; YQ; cJ$  
nThreadID = id;
)T9;6R$b  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 bG"HD?A_  
} d^PD#&"g  
T'E] i!$  
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public void run() F9-[%l  
{ uS~#4;R   
while(nStartPos < nEndPos && !bStop) T=WNBqKo]  
{ UH[<&v  
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try{ zJ;Rt9<7-  
URL url = new URL(sURL); nTPB,QE<  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); xq2V0Jp1u  
httpConnection.setRequestProperty("User-Agent","NetFox"); +=7:4LFOL  
String sProperty = "bytes="+nStartPos+"-"; `ruNA>M  
httpConnection.setRequestProperty("RANGE",sProperty); ]fZ<`w8u}  
Utility.log(sProperty); @dl8(ILk'  
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InputStream input = httpConnection.getInputStream(); WSRy%#  
//logResponseHead(httpConnection); P|N2R5(>T  
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byte[] b = new byte[1024]; ?OE#q$g  
int nRead; um7o!yg,  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) r4u z} jl{  
{ X1oGp+&  
nStartPos += fileAccessI.write(b,0,nRead); Oa! m  
//if(nThreadID == 1) I.1D*!tz  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Y6
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} Z&Ue|Z4Qt  
+c--&tBo  
UP2}q?4  
Utility.log("Thread " + nThreadID + " is over!"); F?9SiX[\  
bDownOver = true; Di>rO038  
//nPos = fileAccessI.write (b,0,nRead); L;S}s, 2x  
} qy ,"X)^#  
catch(Exception e){e.printStackTrace ();} kx:j
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} ?R|th Z  
} W m . }Zh  
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//打印回应的头信息 4J5pXlzV  
public void logResponseHead(HttpURLConnection con) FbAW_Am(  
{ <C'Z H'p  
for(int i=1;;i++) v`x|]-/M&  
{ :'}@Al9=>  
String header=con.getHeaderFieldKey(i); 'Dath>Y=  
if(header!=null) v>H=,.`0\  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); D<bI2  
Utility.log(header+" : "+con.getHeaderField(header)); G(/DtY]  
else %?9Ok  
break; z\TLsx  
} ^z~~VBv  
} +6l]]*H  
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public void splitterStop() gzf-)J  
{ wC`;f5->  
bStop = true; ZSB?Y1wG  
} l+zb~  
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} $shp(T,q  
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/* 7O)" `  
**FileAccess.java FOH@OY  
*//文件访问(定位，写) w<NyV8-hL  
package NetFox; 1$pb (OK  
import java.io.*; 6o=G8y  
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public class FileAccessI implements Serializable{ T2=HG Z  
s_[VHPN  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 DMn4ll|  
RandomAccessFile oSavedFile; $4m*kQ  
long nPos; $SY]fNJQ  
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@MbVWiv  
public FileAccessI() throws IOException fThgK;Qy'U  
{ n?xTkkr0  
this("",0); tU@zhGb  
} "35A/V  
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public FileAccessI(String sName,long nPos) throws IOException ,SUT~oETP  
{ 7K;!iX<d  
oSavedFile = new RandomAccessFile(sName,"rw"); Q.Aa{d9e  
this.nPos = nPos; !wE}(0BTx  
oSavedFile.seek(nPos); h4)Bs\==mT  
} @S^ASDuQU7  

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public synchronized int write(byte[] b,int nStart,int nLen) ny*i+4Mb  
{ O.QK"pKD\  
int n = -1; FX}Gt=  
try{ >IfV\w32  
oSavedFile.write(b,nStart,nLen); vFv3'b$;G  
n = nLen; G~,:2 o3  
} WsGths+[  
catch(IOException e) l\OLyQ  
{ KP
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e.printStackTrace (); 0~Gle:  
} WFTvOFj  
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return n; zM#sOg  
} H t(n%;<  
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o\VUD  
} (s<s@`  
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/* ac{?+]8}  
**SiteInfoBean.java ?)D^~/ A  
*/ b KtD"JG\  
package NetFox; S\i@s_  
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public class SiteInfoBean { zp}eLm:=d  
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private String sSiteURL; //Site's URL 4T6 {Y  
private String sFilePath; //Saved File's Path _}xd}QW  
private String sFileName; //Saved File's Name I:cg}JZ>|  
private int nSplitter; //Count of Splited Downloading File i1lBto[  
S$,'Q^~K  
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public SiteInfoBean() w;6bD'.>;  
{//nSplitter的缺省值为5 Lh.b5Q|  
//default value of nSplitter is 5 M5357Q  
this("","","",5); NPa\Cg[  
} co8"sz0(U  
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MGS-4>Q#  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Qn@Pd*DR  
{ 'a6<ixgo0  
sSiteURL= sURL; O^Q7b7}y  
sFilePath = sPath; w8S!%abl1  
sFileName = sName; k <iTjI*N  
this.nSplitter = nSpiltter; n{*D_kM(H  
"*1f;+\  
 {^a36i  
} D,v U  
"\C$   
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public String getSSiteURL() GzXUU@p  
{ ^!<dgBNj  
return sSiteURL; H,3\0BKk  
} OJ
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:}8Z@H!KkY  
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public void setSSiteURL(String value) 'rp }G&m  
{ Mips.Bx  
sSiteURL = value; D"(L5jR8m@  
} g[RI.&?  
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public String getSFilePath() e
}/Lk5q!  
{ &s Pq<lo  
return sFilePath; Z>c3  
} lGwl1,=  
RqEH|EUZ  
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public void setSFilePath(String value) R'EUV0KX>Y  
{ 7w,FX.=;cv  
sFilePath = value; DI
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} d@`M CchCB  
JWvjWY2+P  
x3jb%`o#!  
public String getSFileName() %VYAd)gC  
{ x-OA([;/  
return sFileName; f=C,e/sw  
} eAv4FA4g  
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uH/w\v_I  
public void setSFileName(String value) Y}#h5\  
{ z%MW!x  
sFileName = value; r.3/
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} j 8*ZF  
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+zXEYc  
public int getNSplitter() ]8q3>  
{ JlMT<;7\  
return nSplitter; #e' }.4cr  
} p' M%XBu  
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~|<WHHN
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public void setNSplitter(int nCount) \
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{ bM8If"  
nSplitter = nCount; mPI8_5V8]  
} 0/S_e)U  
} L}@c
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/* }*.0N;;C  
**Utility.java *K> l*l(f]  
*/ =]:>"_jN  
package NetFox; GKN%Tv:D_  
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public class Utility { =FE|+!>PA  
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public Utility() K>*a*[t0Sy  
{ -S3MH1TZ  
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} 9U$EJN_G  
^G6RjJxqp8  
//线程睡眠 vAyFmdJ^  
public static void sleep(int nSecond) CPNL 94x  
{ >3z5
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try{ &u#&@J  
Thread.sleep(nSecond); N[kwO1  
} | WvUq  
catch(Exception e) w)Covz'uf  
{ @V03a )6,h  
e.printStackTrace (); Eb=}FuV  
} ^Z:~91Tv-_  
} jDQZQ NS  
^f# FI&  
//日志 os/vtyP:a  
public static void log(String sMsg) [IK  )  
{ R: l&2k@  
System.err.println(sMsg); V}\~ugN)y  
} bV ZMW/w  
],P;WPU  
v{}#?=I5  
public static void log(int sMsg) ,"B+r6}EF  
{ HttiX/2~  
System.err.println(sMsg); `w]s
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} y@\V+  
} Yo[;W vu  
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/* E9;|'Vy<E  
**TestMethod.java l
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*/ !?|Th5e  
package NetFox; CiB%B`,N  
,?L2wl[  
ki85!k=Q2  
public class TestMethod { % LJs  
J>/w5$h5  
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public TestMethod() x g0iN'e'K  
{ ///xx/weblogic60b2_win.exe ,_Z+8  
try{ j?MAED  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {)-aSyw
e  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); wXsmn1w9  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ~R(%D-k  
fileFetch.start(); )E~79!  
} /iX+R@  
catch(Exception e){e.printStackTrace ();} {?yr'*  
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} ]Ux<aiY]a  
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public static void main(String[] args) ]MxC_V+P`  
{ {7)st
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new TestMethod(); ub|V\M{  
} Yl3n2R /U  
} 5=f|7yl  
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