http断点续传简单实现（java)

/* BQm H9g|2  
**SiteFileFetch.java `.n[G~*w~1  
*/ ]_-<[0  
package NetFox; B!,})F$x  
import java.io.*; C@K@TfK!M  
import java.net.*; ,+2ytN*  
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public class SiteFileFetch extends Thread { .; :[sv)  
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SiteInfoBean siteInfoBean = null; //文件信息Bean sYvO"|  
long[] nStartPos; //开始位置 mFT[[Z#  
long[] nEndPos; //结束位置 uvT]MgT
  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 l?ofr*U&-x  
long nFileLength; //文件长度 es.`:^
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boolean bFirst = true; //是否第一次取文件 2lQ'rnqS)  
boolean bStop = false; //停止标志 rK];2[U  
File tmpFile; //文件下载的临时信息 Zcc6E2  
DataOutputStream output; //输出到文件的输出流 IKpNc+;p  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） *F=wMWa  
public SiteFileFetch(SiteInfoBean bean) throws IOException 2Ddrxc>48  
{ hF6EOCY6D  
siteInfoBean = bean; )4j#gHN\  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); &0M^UvO  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 98x(2fCvF(  
if(tmpFile.exists ()) WFtxEIrl3j  
{ GX\/2P7CZ  
bFirst = false; " 4s,a  
read_nPos(); (d_{+O"  
} _,5(HETE2  
else U:ZklDW  
{ #\w~(Nm-  
nStartPos = new long[bean.getNSplitter()]; Rf7py)  
nEndPos = new long[bean.getNSplitter()]; ^}9Aq $R  
} [~ fJ/  
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} uRJLSt9m  
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public void run() ! XA07O[@  
{ e%"L79Of6)  
//获得文件长度 ceAK;v o  
//分割文件 lv,<[Hw1  
//实例FileSplitterFetch <jfi"SJu  
//启动FileSplitterFetch线程 2Ui)'0  
//等待子线程返回 {4UlJ,Z.n  
try{ x2;92I{5C,  
if(bFirst) RoPz?,u  
{ 6Vi #O^>  
nFileLength = getFileSize(); iugTXZ(  
if(nFileLength == -1) 'R= r9_%  
{ -]HO8}-Rjs  
System.err.println("File Length is not known!"); ?mnwD]u  
} M++*AZ  
else if(nFileLength == -2) A-uEZj_RD=  
{ r'-)@|  
System.err.println("File is not access!"); LDO@$jg  
} s>^*GQw  
else (Zx;GS  
{ ]e 81O#t3  
for(int i=0;i<nStartPos.length;i++) R:zjEhH)  
{ 8z\WyDz  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); cvi+AZ=  
} C^]bXIb  
for(int i=0;i<nEndPos.length-1;i++) Bx;bc  
{ I 91`~0L*  
nEndPos = nStartPos[i+1]; Qr$uFh/y  
} {V,rWg  
nEndPos[nEndPos.length-1] = nFileLength; BHqJ~2&FDW  
}
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} :43K)O"  

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//启动子线程 >
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; DM"`If%3j  
for(int i=0;i<nStartPos.length;i++) -&y{8<bu4H  
{  ]Ocf %(  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), a'rN&*P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ^!!@O91T  
nStartPos,nEndPos,i); RR*<txdN  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); n"$D/XJO  
fileSplitterFetch.start(); %mg |kb6n  
} =D<46T=(RB  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 1vu=2|QN  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); UPA))Iv>  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", E:L =>}  
nEndPos = " + nFileLength); ^7V9\Q9  
// fileSplitterFetch[nPos.length-1].start(); aV,>y"S  
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//等待子线程结束
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//int count = 0; j8YMod=  
//是否结束while循环 K>"M#T  
boolean breakWhile = false; \,oT(p4N%M  
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while(!bStop) ?&j[Rj0pH  
{ JstX# z  
write_nPos(); 6uOR0L  
Utility.sleep(500); >n{(2bcFs  
breakWhile = true; 9co1+y=i{  
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for(int i=0;i<nStartPos.length;i++) X2/
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{ s+$l.aIO!  
if(!fileSplitterFetch.bDownOver) %Hp
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{ *4dA(N\k"  
breakWhile = false; ~W_m<#K(  
break; #92:h6  
} 1ki##v[ W8  
} 8J7xs6@  
if(breakWhile) ; P&Ka  
break; W:ih#YW_F  
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//count++; xzbyar<  
//if(count>4) OIe {Sx{y  
// siteStop(); )UO:J7K  
} ==l p\  
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System.err.println("文件下载结束！"); HJ:s)As  
} &NL=Bd  
catch(Exception e){e.printStackTrace ();} r*OSEzGUz  
} 1.4]T, `  
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//获得文件长度 k:nr!Y<  
public long getFileSize() TwqyQ49  
{ x}?y@.sn8  
int nFileLength = -1; j*Ta?'*  
try{ E;fYL]j/oZ  
URL url = new URL(siteInfoBean.getSSiteURL()); {+0]diD  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |K YONQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); *RD9gIze  
><mZOTn e;  
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int responseCode=httpConnection.getResponseCode(); ]8NNxaE3(  
if(responseCode>=400) q&B'peT
 
{ rbHrG<+7zO  
processErrorCode(responseCode); 1Thr74M  
return -2; //-2 represent access is error EW%%W6O6  
} Cg?D<l4  
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 Jx9S@L`  
String sHeader; B;r U  
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for(int i=1;;i++) >Vy=5)/i  
{ WO?EzQ ?  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); mk2T  
//Utility.log(in.readLine()); #oSQWC=T  
sHeader=httpConnection.getHeaderFieldKey(i); OB)Vk  
if(sHeader!=null) zmQ V6o=k  
{ T^B&GgW  
if(sHeader.equals("Content-Length")) *91iFeKj=  
{ %6j|/|#]  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); rk*Igqf  
break; c9/w-u~j  
} z9}rT<hy  
} y44FejH(v  
else 'g$~ij ;x  
break; .^>[@w3  
} <mjH#aSy  
} )HNbWGu  
catch(IOException e){e.printStackTrace ();} C18pK8-  
catch(Exception e){e.printStackTrace ();} }jBr[S5  
}00mJ]H(  
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Utility.log(nFileLength); $IX>o&S@|  
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return nFileLength; m8,P-m  
} JM!rop^  
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:BKY#uH~  
//保存下载信息（文件指针位置） Q%KH^<  
private void write_nPos() z)xGZ*{=  
{ )28Jz6.I  
try{ %Ez%pT0TQ#  
output = new DataOutputStream(new FileOutputStream(tmpFile)); A^ $9[_  
output.writeInt(nStartPos.length); wvvMesX<L  
for(int i=0;i<nStartPos.length;i++) xfCq;?MupW  
{ #qWa[k
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// output.writeLong(nPos); AX}l~ sv  
output.writeLong(fileSplitterFetch.nStartPos); gm~Ka%O|F  
output.writeLong(fileSplitterFetch.nEndPos); <use+C2  
} ~j}di^<{  
output.close(); G`!#k!&r  
} 2c@4<kyfP  
catch(IOException e){e.printStackTrace ();} Yf&x]<rkCp  
catch(Exception e){e.printStackTrace ();} g#ubxC7t<  
} 
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//读取保存的下载信息（文件指针位置） +Wh0Of  
private void read_nPos() w]X~I/6g  
{ +Rn]6}5m\  
try{ =Y#)c]`  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); T5?@'b8F6  
int nCount = input.readInt(); [U@#whEO  
nStartPos = new long[nCount]; >M[wh>  
nEndPos = new long[nCount]; Zy _A3m{  
for(int i=0;i<nStartPos.length;i++) sYM3&ikyHI  
{ Tu95qL~^  
nStartPos = input.readLong(); uoR_/vol8  
nEndPos = input.readLong();
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} uq~$HXd
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input.close(); ce!0Ws+  
} ?ORG<11a  
catch(IOException e){e.printStackTrace ();} <x@brXA  
catch(Exception e){e.printStackTrace ();} ' _Ij9{M  
} pE<dK.v6  
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private void processErrorCode(int nErrorCode) V`qHNM/t  
{ Mu$9
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System.err.println("Error Code : " + nErrorCode); @T[}]e  
} hi4#8W
 
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//停止文件下载 Wm\HZ9PN  
public void siteStop() .si!`?K%[  
{ ew -5VL   
bStop = true; dlkxA^  
for(int i=0;i<nStartPos.length;i++) \g&P5  
fileSplitterFetch.splitterStop(); ={P  
a<-NB9o~v  
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} hAq7v']m  
} V("@z<b|  
//负责部分文件的抓取 +EG?8L,z  
**FileSplitterFetch.java 7(c7-  
*/ ZdG?fWWA  
package NetFox; uj#bK 7  
j6<o,0P  
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import java.io.*; <Vucr   
import java.net.*; GBnf]A,^@  
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public class FileSplitterFetch extends Thread { ?t<yk(q  
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String sURL; //File URL <j CD^  
long nStartPos; //File Snippet Start Position =(\ /+ 0-[  
long nEndPos; //File Snippet End Position K[}5bjh>  
int nThreadID; //Thread's ID aVTTpMY  
boolean bDownOver = false; //Downing is over 2P)*Y5`KBH  
boolean bStop = false; //Stop identical J*HZ=6L  
FileAccessI fileAccessI = null; //File Access interface 7;0$UYDU*  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException YI[y/~!  
{ o[<lTsw<  
this.sURL = sURL; 2^Y@e=^A  
this.nStartPos = nStart; Op''=Ar#sh  
this.nEndPos = nEnd; !<`}mE!:  
nThreadID = id; J*V@huF  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 jm~(OLg  
} %&EDh2w>  
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public void run() xnz(hz6  
{ }~/u%vI@M5  
while(nStartPos < nEndPos && !bStop) *WS'C}T  
{ A\Ax5eeL  
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try{ *hugQh]a  
URL url = new URL(sURL); 8&d
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2RW^Nqc9  
httpConnection.setRequestProperty("User-Agent","NetFox"); <$m=@@qg  
String sProperty = "bytes="+nStartPos+"-"; bD*z"e  
httpConnection.setRequestProperty("RANGE",sProperty); gZ{q85C.>  
Utility.log(sProperty); |n9q4*dN  
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InputStream input = httpConnection.getInputStream(); F|Y}X|x8Q  
//logResponseHead(httpConnection); b \pjjb[  
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byte[] b = new byte[1024]; ZH o#2{F  
int nRead; 4[q'1N6-  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) X9:4oMux7  
{ Z{'.fq2A  
nStartPos += fileAccessI.write(b,0,nRead); .)eJL  
//if(nThreadID == 1) QtF'x<cB  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); t,CC~  
} zxo0:dyw7  
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Utility.log("Thread " + nThreadID + " is over!"); K@0gBgN  
bDownOver = true; 0/r\#"+XT  
//nPos = fileAccessI.write (b,0,nRead); S`N_},  
} (YOp  
catch(Exception e){e.printStackTrace ();} \1^qfw  
} `#v(MK{9+V  
} HizMjJ|  
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//打印回应的头信息 9lT6fW`v1Q  
public void logResponseHead(HttpURLConnection con) xt{f+c@P  
{ k{{iF  
for(int i=1;;i++) ?AL;m.X-@  
{ C^dnkuA  
String header=con.getHeaderFieldKey(i); t&GjW6]W  
if(header!=null) k@,&'imx  
//responseHeaders.put(header,httpConnection.getHeaderField(header));  xr }jw  
Utility.log(header+" : "+con.getHeaderField(header)); ]GSs{'UhB  
else o*d+W7l  
break; U}r^M( s!  
} 6f$h1$$)^  
} Y<A593  
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public void splitterStop() +`@)87O  
{ d8Keyi8[  
bStop = true; >x$eKN  
} 2E@ !  
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} Cfz020u`g  
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/* `#X\@?'5  
**FileAccess.java ka3(sctZ5  
*//文件访问(定位，写) w]BZgF.  
package NetFox; l1Zf#]x  
import java.io.*; pi'w40!:  
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public class FileAccessI implements Serializable{ B{:JD^V!  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 DOr()X  
RandomAccessFile oSavedFile; z[7j`J|Kk  
long nPos; >&1
MD}  
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public FileAccessI() throws IOException U~,~GU
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{ r9x.c7=O  
this("",0); Sdc yL%6!  
} 1T{A(<:o$  
' 9K4A'2[  
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public FileAccessI(String sName,long nPos) throws IOException M]S&vE{D  
{ CB<i  
oSavedFile = new RandomAccessFile(sName,"rw"); Ol}^'7H  
this.nPos = nPos; :r<uH6x|  
oSavedFile.seek(nPos); M_o<6C  
} L_>j SP  
1gq(s2izy  
'(JSU  
public synchronized int write(byte[] b,int nStart,int nLen) (6xrs_ea  
{ W!$aK)]4u  
int n = -1; 4t(V)1+  
try{ X[ERlw1q4Q  
oSavedFile.write(b,nStart,nLen); <
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n = nLen; |@J:A!  
} ``~7z;E%@  
catch(IOException e) RCFocOOn  
{ =:T pH>f*  
e.printStackTrace (); 6cCC+*V{  
} J/M_cO*U  
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return n; cx]&ae*  
} r!qr'Ht<  
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} _N4G[jQLJ  
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.%{3#\  
/* (T1)7%Xs  
**SiteInfoBean.java MuzlUW]  
*/ /cPezX  
package NetFox; p[E}:kak_-  
jU1([(?"  
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public class SiteInfoBean { 5*.JXxE;U  
@M[t|  
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private String sSiteURL; //Site's URL icq!^5BzL  
private String sFilePath; //Saved File's Path l_K=7\N  
private String sFileName; //Saved File's Name ZK=`Y@  
private int nSplitter; //Count of Splited Downloading File alQMPQVin  
}O_kbPNw  
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public SiteInfoBean() IM
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{//nSplitter的缺省值为5 y be:u  
//default value of nSplitter is 5 jB+K)NXHL  
this("","","",5); +R
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} ]a4rA+NFLB  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) `)sC".b7  
{ ('H[[YODh  
sSiteURL= sURL; (*{Y#XD{  
sFilePath = sPath; K-%x]Fp=  
sFileName = sName; rkdf htpI  
this.nSplitter = nSpiltter; W_w^"'  
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}  T06BrX  
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public String getSSiteURL() `zQ2i}Uju  
{ ;?-A4!V,
 
return sSiteURL; Q8]lz}  
} mB.yb
rig  

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public void setSSiteURL(String value) 5u(,g1s}UZ  
{ : ,0F_["3  
sSiteURL = value; }/dGC;p"  
} AoL2Wrk]\B  
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public String getSFilePath()
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{ *{_WM}G  
return sFilePath; wH?r522`c  
} kU*Fif  
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public void setSFilePath(String value) J|$(O$hYy  
{ E=G"_ ^hCE  
sFilePath = value; n U0  
} tc.`P]R   
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public String getSFileName() vvWje:H  
{ M/!5r  
return sFileName; rMV<}C ^  
} @;^7kt  
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public void setSFileName(String value) 0uw3[,I   
{ 28u3B2\$  
sFileName = value; @<^_ _."  
} h;s~I/e(  
rM|] }M=_V  
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public int getNSplitter() ap 5D6y+  
{ ( E8(np  
return nSplitter; e*nT+Rp  
} +{eZ@  
KG2ij~v  
;!k{{Xndd  
public void setNSplitter(int nCount) f:w#r.]
 
{ >Rnj6A|Q  
nSplitter = nCount; 1u%e7  
} :!fP~(R'm  
} equ|v~@y  
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#z(
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/* vX9B^W||x  
**Utility.java K #f*LV5  
*/ +"~~;J$  
package NetFox; \!]Zq#*kH  
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public class Utility { c@uNA0 p
 
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public Utility() o<J_?7c~}  
{ 6wmMg i_m  
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} cb9ndZ)v.  
fw[Z7`\Q5  
//线程睡眠 8M"0o}wx  
public static void sleep(int nSecond) 0/vmj,&B(  
{ P ~sX S  
try{ IM^K]$q$47  
Thread.sleep(nSecond); !_ng_,J  
} 2$Fy?08q  
catch(Exception e) U}=o3u  
{ &~6W!w  
e.printStackTrace (); Ki8]+W37  
} &:}{?vU  
} e*zt;SR  
}8zw| (GR,  
//日志 ~.dmfA{  
public static void log(String sMsg) t/3t69\x  
{ tbNIl cAWS  
System.err.println(sMsg); A<+veqb4  
} Zeeixg-1<  
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public static void log(int sMsg) @5C!`:f  
{ K).Gj2 $  
System.err.println(sMsg); Aw
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} @_+B'<2  
} Ag6^>xb^  
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/* .[qm>j,  
**TestMethod.java T+0Z2H  
*/ d7*fP S  
package NetFox; pI>[^7  

';\v:dP  
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public class TestMethod { :O~*}7
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public TestMethod() dpTeF`N  
{ ///xx/weblogic60b2_win.exe iz0GL&<  
try{ -fB;pS,  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); J'=iEI  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); #ox&=MY  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ==?!z<I.d  
fileFetch.start(); GjfPba4>  
} G%RL8HU  
catch(Exception e){e.printStackTrace ();} 3om_Z/k  
nc.(bb),  
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} Hy9c<X[F9  
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public static void main(String[] args) ?uBZ"^'  
{ RM(MCle}  
new TestMethod(); U=G}@Y  
} L (#DVF  
} xeGl}q|  
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