http断点续传简单实现（java)

/* /j/%wT2m  
**SiteFileFetch.java <^_Vl8%  
*/ 6CmFmc,  
package NetFox; U hhmG+  
import java.io.*; XWQ0V
  
import java.net.*; >#U<#  
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public class SiteFileFetch extends Thread { {4aY}= -Q*  
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SiteInfoBean siteInfoBean = null; //文件信息Bean H8]^f=  
long[] nStartPos; //开始位置 sg"D;b:X  
long[] nEndPos; //结束位置 Z"|P(]A  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 XJ~l5}y ]  
long nFileLength; //文件长度 nSQ}yqM)  
boolean bFirst = true; //是否第一次取文件 sLi//P?:t  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 7QiCZcb\  
DataOutputStream output; //输出到文件的输出流 xyjVdD\  
'
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） kz;_f  
public SiteFileFetch(SiteInfoBean bean) throws IOException `N.$LY;8  
{ eoe^t:5&  
siteInfoBean = bean; Qr%Jm{_o  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 9Y%?)t.2  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); '
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if(tmpFile.exists ()) 6Hbf9,vI  
{ mhLRi\[c )  
bFirst = false; _<*GU@  
read_nPos(); 2C]la  
} 7$'mC9  
else SKpPR;=q|:  
{ $dp#nyP  
nStartPos = new long[bean.getNSplitter()]; 7(~H77  
nEndPos = new long[bean.getNSplitter()]; kTZx-7~  
}
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} `$sY^EX  
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public void run() >`<2}Me6  
{ {ogZT7w}  
//获得文件长度 Dp*$GQ  
//分割文件 1:x
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//实例FileSplitterFetch YqSXi~.  
//启动FileSplitterFetch线程 r%,H*DOu  
//等待子线程返回 _7#tgZyv  
try{ ]AA%J@  
if(bFirst) U\Ar*b)/T  
{ bLM"t0  
nFileLength = getFileSize();
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if(nFileLength == -1) \FoxKOTp  
{ 7ITl3>  
System.err.println("File Length is not known!"); 1.0!H.>q  
} CC>fm1#i\  
else if(nFileLength == -2) >U~|R=*  
{ ?S&w0}R  
System.err.println("File is not access!"); sVZZ
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} ljJz#+H2_  
else lke
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{ >GznG[Ku  
for(int i=0;i<nStartPos.length;i++) +:,`sdv6o  
{ rFq@]t3q  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); N8XC~Dh{  
} r[v-?W'  
for(int i=0;i<nEndPos.length-1;i++) +~4bB$6*4)  
{ &6t3SZV  
nEndPos = nStartPos[i+1]; a}Fkx  
} Sc'c$/  
nEndPos[nEndPos.length-1] = nFileLength; pH\^1xj =  
} k?HrD"k"  
} }
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//启动子线程 =\Vu=I  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; kWs+2j  
for(int i=0;i<nStartPos.length;i++) ^V: "zzn&  
{ ?cO8'4 bq  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), L8dU(P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), >Qm<-g  
nStartPos,nEndPos,i); lkg"'p{  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); R#
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fileSplitterFetch.start(); e$Bf[F#;-  
} G;Wkm|  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7V=MRf&xQ  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); EDHg'q  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ",  )8$:DW;  
nEndPos = " + nFileLength); !eR-Kor  
// fileSplitterFetch[nPos.length-1].start(); g%\$ !b  
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//等待子线程结束
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//int count = 0; AbF(MK=i  
//是否结束while循环 &]VQR2J}:  
boolean breakWhile = false; !{Q:(B#ec  
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while(!bStop) %GX uuE}mX  
{ U=kx`j>  
write_nPos(); ~M ,{ _  
Utility.sleep(500); 5pM&h~M
 
breakWhile = true; `V&1]C8x  
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for(int i=0;i<nStartPos.length;i++) PUP"ky^q"  
{ e"fN~`NhY  
if(!fileSplitterFetch.bDownOver) ;}/U+`=D?  
{ tyEPU^PM  
breakWhile = false; ?GO SeV  
break; j2}  
} j,C,5l=  
} j0iAU1~_VX  
if(breakWhile) 1yBt/
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break; :xFu_%7  
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//count++; V#0 dGP-Z  
//if(count>4) 8K0X[-hs8  
// siteStop(); q^a|
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} D<U 9m3  
\ ]   
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System.err.println("文件下载结束！"); C$<"w,  
} VEj$^bpp5s  
catch(Exception e){e.printStackTrace ();} S]&8St  
} #bT8QbJ(  
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//获得文件长度 0#oBXu  
public long getFileSize() sM9FE{,mx  
{ qoj^_s6  
int nFileLength = -1; bMN@H\Ek  
try{ D|d4:;7  
URL url = new URL(siteInfoBean.getSSiteURL()); 7
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); mC i[Ps  
httpConnection.setRequestProperty("User-Agent","NetFox"); .u1X+P7  
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int responseCode=httpConnection.getResponseCode(); mZ~qG5@/F  
if(responseCode>=400) LY]nl3{E  
{ kE/`n],1U  
processErrorCode(responseCode); z %x7fe  
return -2; //-2 represent access is error )K~w'TUr  
} l~bKBz  
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String sHeader; [X,A'Q  
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for(int i=1;;i++) C
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{ ?Z q_9T7  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); w*50ZS;N  
//Utility.log(in.readLine()); AL$W+')  
sHeader=httpConnection.getHeaderFieldKey(i); bGv*-;*  
if(sHeader!=null) 'p%=<0vrr  
{ ZJ;LD*  
if(sHeader.equals("Content-Length")) *'D=1{WZ!  
{ gH %y  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); w |_GV}#_  
break; o+nG3kRD  
} xXX/]x>  
} ><;Q@u5~  
else kt^yj"C>  
break; NYBe"/}GS  
} 5h0>!0  
} R A:jzht  
catch(IOException e){e.printStackTrace ();} ![ZmV  
catch(Exception e){e.printStackTrace ();} (;aB!(_  
[,=d7*b(l  
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Utility.log(nFileLength); Lf. 1>s  
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return nFileLength; -G9|n#zCU  
} G.g|jP'n  
6vto++  
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//保存下载信息（文件指针位置） #EbGL])F}  
private void write_nPos() s5l3V2k  
{ Jf7frzw  
try{ GnFs63  
output = new DataOutputStream(new FileOutputStream(tmpFile)); B'-I{~'/  
output.writeInt(nStartPos.length); Wta]BX  
for(int i=0;i<nStartPos.length;i++) ~-TOsRvxR  
{ 8pXKO"u],  
// output.writeLong(nPos); *8bK')W  
output.writeLong(fileSplitterFetch.nStartPos); hq#kvvi{f  
output.writeLong(fileSplitterFetch.nEndPos); 9Bz0MUbrLl  
} <l$P&jSF3  
output.close(); xCWz\-;  
} A\z`c e!  
catch(IOException e){e.printStackTrace ();} {Oj7  
catch(Exception e){e.printStackTrace ();} -gS"pE^1  
} jin db#)bz  
#;[Bl=3(  
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//读取保存的下载信息（文件指针位置） G?`-]FMO  
private void read_nPos() ;+ azeW^  
{ 9#7J:PfZ<  
try{ zB*euHIqZ  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); L@RIZu>ZW+  
int nCount = input.readInt(); hN   
nStartPos = new long[nCount]; -v]Qhf&>  
nEndPos = new long[nCount]; y,E.SB  
for(int i=0;i<nStartPos.length;i++) s)zJT  
{ }`xdWY  
nStartPos = input.readLong(); _;hf<|c  
nEndPos = input.readLong(); ^~$\ g]  
} 03=5Nof1  
input.close(); ?]#OM_,8  
} 3J~0O2  
catch(IOException e){e.printStackTrace ();} W@.Ji B  
catch(Exception e){e.printStackTrace ();} j8++R&1f]  
} =su]w2,Iy  
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private void processErrorCode(int nErrorCode) wpXgPVZT  
{ 2N5`'  
System.err.println("Error Code : " + nErrorCode); v4rW2F:X  
} :^i^0dC  
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//停止文件下载 -)v@jlg02  
public void siteStop() d(-EcY>?  
{ irbw'^;y  
bStop = true; R_ ZK0ar  
for(int i=0;i<nStartPos.length;i++) O^Q,-=tA\  
fileSplitterFetch.splitterStop(); c6&Q^p|CF  
0 Y>M=|  
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} ` qUX.  
} Es!Q8.  
//负责部分文件的抓取 kGHQ`h  
**FileSplitterFetch.java jq-l5})h  
*/ eF~dQ4RZ  
package NetFox; ;W]\rft[  
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import java.io.*; /@"Y^  
import java.net.*; :"Y*<=x#2  
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public class FileSplitterFetch extends Thread { w(9*7pp  
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String sURL; //File URL &c>?~-!W  
long nStartPos; //File Snippet Start Position /3!
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long nEndPos; //File Snippet End Position o]ePP,  
int nThreadID; //Thread's ID ]
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boolean bDownOver = false; //Downing is over TP%+.#Fu  
boolean bStop = false; //Stop identical .fAv*pUzU  
FileAccessI fileAccessI = null; //File Access interface M}O}:1Par  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException kV;fD$iW;  
{ 7fHc[,  
this.sURL = sURL; .uF[C{RnO  
this.nStartPos = nStart; nXy>7H[0  
this.nEndPos = nEnd; Q>Qibr  
nThreadID = id; g%nl!dgS  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 $pyOn2}  
} [P~hjm
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public void run() K2{aNvR)t  
{ k(t}^50^j  
while(nStartPos < nEndPos && !bStop) _oG&OJ@  
{ bq>_qpr  
=K\r-'V  
*=AqM14 @  
try{ Fv74bC%  
URL url = new URL(sURL); h[o6-f<D  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); zZ=pP5y8  
httpConnection.setRequestProperty("User-Agent","NetFox"); #bX9Tu0  
String sProperty = "bytes="+nStartPos+"-"; 99xEm  
httpConnection.setRequestProperty("RANGE",sProperty); -fS.9+k0/  
Utility.log(sProperty); 2ZcKK8X;7  
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InputStream input = httpConnection.getInputStream(); MUnEuhXTr  
//logResponseHead(httpConnection); [F!Y%Zp  

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byte[] b = new byte[1024]; ]\ !5}L  
int nRead; R:X0'zeRr  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) T*g:# ^4  
{ i|`dWOVb  
nStartPos += fileAccessI.write(b,0,nRead); 9h&R]yz;  
//if(nThreadID == 1) aJ Z"D8C  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Gg Jf7ie4  
} -m *Sq  
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Utility.log("Thread " + nThreadID + " is over!"); 21hv%CF\9  
bDownOver = true; ^XbU~3(  
//nPos = fileAccessI.write (b,0,nRead); w| `h[/,  
} js iSg/  
catch(Exception e){e.printStackTrace ();} WHXj8*]6  
} ,#MCn  
} 2c6g>?  
4}+/F}TbJ5  
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//打印回应的头信息 7xRl9  
public void logResponseHead(HttpURLConnection con) v~QHMg  
{ HK`I\,K  
for(int i=1;;i++) ZKHG!`X0  
{ pRkP~ZISU  
String header=con.getHeaderFieldKey(i); )nL`H^  
if(header!=null) svxw^0~a  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Mmpfto%i  
Utility.log(header+" : "+con.getHeaderField(header)); _XCOSomL`  
else >
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break; hxQqa 0B  
} 3k#~yaoI  
} ]vwW]O7
  
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public void splitterStop() -py@DzK  
{ FEVEp  
bStop = true; Tg!m`9s+  
} ~e6Brq  
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} Ym3\pRFiD  
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/* 'yMF~r3J  
**FileAccess.java ggJO:$?$L  
*//文件访问(定位，写) *S2ypzwRZ,  
package NetFox; [Xb@Wh:yG  
import java.io.*; nBk)WX&[K  
uj :%#u  
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public class FileAccessI implements Serializable{ ~\J}Kqg  
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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 ,^uEYT}j  
RandomAccessFile oSavedFile; ]]zPq<b2  
long nPos; z^T`x_mF  
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public FileAccessI() throws IOException [VE
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{ /`mks1:pK  
this("",0); <J^MCqp!v  
} %
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public FileAccessI(String sName,long nPos) throws IOException e)(wss+d7P  
{ nDHTV!]<  
oSavedFile = new RandomAccessFile(sName,"rw"); oH_;4QU4y  
this.nPos = nPos; =3L;Z[^9  
oSavedFile.seek(nPos); x QIq^/F0  
} @)fd}tV  
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public synchronized int write(byte[] b,int nStart,int nLen) ,^C--tgZJg  
{ k |eBJ%  
int n = -1; 2AMo:Jqv  
try{ u:=7l  
oSavedFile.write(b,nStart,nLen); q^Y-}=w  
n = nLen; 'IwNTM  
} <ZNzVnVA  
catch(IOException e) RS8Hf~0G  
{ \SBc;  
e.printStackTrace (); b:TLV`>/&  
} !qWH`[:  
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return n; ,%M$0poKM  
} mWsI}2  
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;  
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} 2+e}*&iQpp  
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/* oC0qG[yp9S  
**SiteInfoBean.java njputEGX  
*/ >&}%+r\  
package NetFox; >s<^M|S07  
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public class SiteInfoBean { =,6z4" )  
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private String sSiteURL; //Site's URL ]SLP}Jwy  
private String sFilePath; //Saved File's Path toBHkiuD  
private String sFileName; //Saved File's Name &7K?
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private int nSplitter; //Count of Splited Downloading File cWe"%I  
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public SiteInfoBean() [q8 P~l  
{//nSplitter的缺省值为5 )QU  
//default value of nSplitter is 5 ! t?iXZ  
this("","","",5); :%,:"  
} Ezd_`_@R  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 4\8+9b\9"  
{ 1cpiHZa  
sSiteURL= sURL; jK& h~)  
sFilePath = sPath; 5>D>% iaHv  
sFileName = sName; Q7jb'y$ozO  
this.nSplitter = nSpiltter; h7lDHIQf  
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} 3sy (vC  
;;6uw\6 O  
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public String getSSiteURL() a%/9v"}  
{ s@K4u^$A  
return sSiteURL; 8 Hg+H=?  
} 2fn&#kw/  

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public void setSSiteURL(String value) TJ6*t!'*X  
{ A>o*t=5  
sSiteURL = value; 5K>3My
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} +0nJ  
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public String getSFilePath() 4;yKOQD|
 
{ JfLqtXF[&"  
return sFilePath; l5!|I:
/*;  
} eD?tLj  
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public void setSFilePath(String value) v3~?;f,l  
{ _=F=`xu  
sFilePath = value; }ppN k:B  
} <Tzrj1"Q3  
D9^h; 8  
n|Q@UPb/=  
public String getSFileName() cUKE   
{ .WA-&b_  
return sFileName; CQF:Rnb  
} 5Ha9lM2gh  
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public void setSFileName(String value) Lo{ E:5q  
{ G|!Tj X7s  
sFileName = value; vlmB`T  
} qouhuH_WtJ  
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0l)~i''  
public int getNSplitter() n'n/Tu   
{ ;K:zmH  
return nSplitter; bzBEX mC  
} 4&<oFW\r  
i[7\[  
^}/PGG\~r  
public void setNSplitter(int nCount) le|~BG hL  
{ 89pEfl j2  
nSplitter = nCount; UZ\u;/}  
} 4":KoS`,j  
} _|kxY'_[8  
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/* >JHryS.j$4  
**Utility.java j4gF;-m<  
*/ N.,X<G.H  
package NetFox; -$,TMqM  
t3 8m'J :>  
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public class Utility { HVR /7&g  
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public Utility() <'y?KiphL  
{ cOmw?kA*G  
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'N (:@]4N  
} V#2+"(7h  
O,{6*[)@  
//线程睡眠 xgVeN["  
public static void sleep(int nSecond) eVjBGJ=2e  
{ <=zQ NBtx  
try{ n\Z!ff/  
Thread.sleep(nSecond); _<n~n]%  
} ZCMw3]*  
catch(Exception e) :;t:H] f  
{ QO<jI#  
e.printStackTrace (); +nrbShV  
} jl4rbzse  
} K -nF lPm\  
~ (|5/ p7t  
//日志 !E<[JM  
public static void log(String sMsg) (5$!MUS~9  
{ EU2$f  
System.err.println(sMsg); |7'df&CA  
} *v;2PP[^  
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\:%(q/v"X  
public static void log(int sMsg) 9&-dTayIz  
{ Sq>dt[7  
System.err.println(sMsg); DrKP%BnS  
} |HiE@  
} dU&a{$ku[  
<Th6r.#?  
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/* g!g#]9j  
**TestMethod.java ,?J!  
*/ |^&b8  
package NetFox; ?&8^&brwG  
{fPy=,>Nb  
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public class TestMethod { @E&J_un  
NW~N}5T  
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public TestMethod() NO*u9YH?  
{ ///xx/weblogic60b2_win.exe @6Y?\Wx$w  
try{ v [wb~uw\  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); QyEnpZ8?a  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); *RI]?j%B  
SiteFileFetch fileFetch = new SiteFileFetch(bean); l.67++_  
fileFetch.start(); |XaIx#n  
} C.WX.Je  
catch(Exception e){e.printStackTrace ();} ~Otq %MQ  
#{\J Nb+w%  
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"  
} [>jbhV'  
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public static void main(String[] args) {3|t;ZHk  
{ |B?cVc0  
new TestMethod(); g#"zQvON  
} HZ aV7dOZ8  
} 1T"`vtR  
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