http断点续传简单实现（java)

/* >4&s7][Q|  
**SiteFileFetch.java HyKv5S$  
*/ 6< O|,7=_  
package NetFox; 0JS#{EDh+  
import java.io.*; y|(C L^(  
import java.net.*; eB,eu4+-  
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public class SiteFileFetch extends Thread { w:+wx/\  
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SiteInfoBean siteInfoBean = null; //文件信息Bean W_%@nm\y  
long[] nStartPos; //开始位置 3;Ztm$8  
long[] nEndPos; //结束位置 &x>8 %Q s  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 &2\^S+4  
long nFileLength; //文件长度 NUp,In_  
boolean bFirst = true; //是否第一次取文件 Cr#Z.  
boolean bStop = false; //停止标志 i^2-PKPg{  
File tmpFile; //文件下载的临时信息 \PJpy^i  
DataOutputStream output; //输出到文件的输出流 `#x}-A$  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） W34_@,GD  
public SiteFileFetch(SiteInfoBean bean) throws IOException @=G6fW:  
{ qnCJrY6]  
siteInfoBean = bean; 5nSi2
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); #$;i 4a  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ll8Zo+-[  
if(tmpFile.exists ())  L$Yg*]\  
{ CS|al(?~  
bFirst = false; nXFPoR)T  
read_nPos(); (`me}8  
} xq-TT2}<L  
else \~~y1.,U.  
{ sm9/sX!  
nStartPos = new long[bean.getNSplitter()]; u-%|ZSg  
nEndPos = new long[bean.getNSplitter()]; Wi%e9r{hU  
} rS&"UH?c7  
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} Ka+N5 T.f  
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public void run() ]**h`9MF  
{ yh:Wg$qx
 
//获得文件长度 q\]"}M8  
//分割文件 vn(ji=  
//实例FileSplitterFetch }Md5a%s<  
//启动FileSplitterFetch线程 A8oTcX_  
//等待子线程返回 o<Y[GW1pg  
try{ :HW\awv  
if(bFirst) {;-wXzv`  
{ >^N{  
nFileLength = getFileSize(); &8xwR   
if(nFileLength == -1) 3<R8_p  
{ TkyP_*  
System.err.println("File Length is not known!"); XSoHh-  
} 4Mck/i2  
else if(nFileLength == -2) Iy8fN"I9D  
{ N.D7  
System.err.println("File is not access!"); QpI\\Zt6  
} lV M)'m  
else ONU,R\jMb-  
{ 7A
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for(int i=0;i<nStartPos.length;i++) U6x$R O!  
{ hy|Yy&-  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Lh;U2pA  
} )~2~q7  
for(int i=0;i<nEndPos.length-1;i++) 7GG:1:2+>  
{ EV.F/Wh  
nEndPos = nStartPos[i+1]; zz**HwRt  
} T:!f_mu|  
nEndPos[nEndPos.length-1] = nFileLength; Sk7sxy<F'  
} /C\tJ
s  
} |9Pi*)E  
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//启动子线程 k;V (rf`  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; )1, U~+JFU  
for(int i=0;i<nStartPos.length;i++) `)WC|=w2  
{ M7gb3gw6  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), *F;W 1TF  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), [M/0Qx[,  
nStartPos,nEndPos,i); f(UB$^4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^{{0ajI9C  
fileSplitterFetch.start(); U ljWBd  
} =lZtI6tZ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), x +]ek  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); =Vat2'>+  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", |A,<m#C  
nEndPos = " + nFileLength); %n@ ^$&,&;  
// fileSplitterFetch[nPos.length-1].start(); Y?#aUQc  
x^~@`]TV^  
8.ej65r*  
//等待子线程结束 ?A]/ M~3B  
//int count = 0; $w+()iI  
//是否结束while循环 k3CHv=U{  
boolean breakWhile = false; M.3ULt8  
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while(!bStop) \&\U&^?  
{ f)1*%
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write_nPos(); 4Is Wp!`W  
Utility.sleep(500); 6lob&+  
breakWhile = true; tUT:
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/
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for(int i=0;i<nStartPos.length;i++) jp880}  
{ sv)4e)1  
if(!fileSplitterFetch.bDownOver) vlC$0P  
{ I3;03X<2  
breakWhile = false; LbUH`0:%t  
break; p`)Mk<`dYD  
} M3!4,_!~  
} 'l $ViNq;  
if(breakWhile) pmc)$3u  
break; ib%'{?Q.  
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//count++; 3R<
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//if(count>4) PwnfXsR  
// siteStop(); 4w#:?Y _\[  
} 1Vx>\A  
!CUM*<iV  
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System.err.println("文件下载结束！"); 8lFYk`|g  
} s1bb2R  
catch(Exception e){e.printStackTrace ();} uaqV)H  
} i hcSSUm  
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//获得文件长度 wGgeK,*_  
public long getFileSize() @k9n0Qe|F  
{ z:oi@q  
int nFileLength = -1; n{(,r'  
try{ ^G14Z5.  
URL url = new URL(siteInfoBean.getSSiteURL()); <9
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); [&pMU)   
httpConnection.setRequestProperty("User-Agent","NetFox"); 1EWskmp  
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cb }OjM F  
int responseCode=httpConnection.getResponseCode(); A [_T~+-G  
if(responseCode>=400) xg;vQKS6  
{ Ui'*$W]v  
processErrorCode(responseCode); ?OFfU  4  
return -2; //-2 represent access is error vLpIVNA]]Y  
} |]eWO#vs  
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String sHeader; e)$a;6  
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for(int i=1;;i++) e"|ZTg+U  
{ i,2eoM)FB  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 3LZvlcLb  
//Utility.log(in.readLine()); {g4`>^;  
sHeader=httpConnection.getHeaderFieldKey(i); <6&Z5mpm$w  
if(sHeader!=null) q;.LK8M  
{ y ~Fi  
if(sHeader.equals("Content-Length")) JC#5CCz  
{ =w7+Yt  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); lE$(*1H  
break; [IgqK5@  
} N!./u(b  
} :}CcWfbT  
else T%aM~dp  
break; z.;!Pj  
} r<
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} 8WpZ"  
catch(IOException e){e.printStackTrace ();} @w(X}q1  
catch(Exception e){e.printStackTrace ();} Z+_xX  
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Utility.log(nFileLength); 0xH&^Ia1B  
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return nFileLength; K%UjPzPWw  
} W4(GI]`_+  
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//保存下载信息（文件指针位置） wli H3vA_  
private void write_nPos() /4;Sxx-  
{ ji<(}d~L*  
try{ 4m6/ba  
output = new DataOutputStream(new FileOutputStream(tmpFile)); =s9*=5r8  
output.writeInt(nStartPos.length); UkcH+0o  
for(int i=0;i<nStartPos.length;i++) \f7R^;`_<R  
{ K{:[0oIHc  
// output.writeLong(nPos); x,HD,VQR/  
output.writeLong(fileSplitterFetch.nStartPos); [x'D+!  
output.writeLong(fileSplitterFetch.nEndPos); .\:MB7p  
} P 1  
output.close(); ^91Ae!)d  
} na@Go@q  
catch(IOException e){e.printStackTrace ();} BS%pS(  
catch(Exception e){e.printStackTrace ();} e ^ZY  
} u/V&1In  
yd[4l%G(zS  
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//读取保存的下载信息（文件指针位置） |Xt6`~iC  
private void read_nPos() _na/&J6  
{ <sSH^J4QqX  
try{ "\u<\CL  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); &?5me:aU  
int nCount = input.readInt(); Mkr &30il[  
nStartPos = new long[nCount]; aq\Fh7  
nEndPos = new long[nCount]; ibLx'<  
for(int i=0;i<nStartPos.length;i++) o#>Mf464I  
{ l| y.6v  
nStartPos = input.readLong(); WJ,?5#  
nEndPos = input.readLong(); = ?BhtW  
} 6 X'#F,
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input.close(); ^Jw=5ImG  
} t{,e{oZx  
catch(IOException e){e.printStackTrace ();} o#WECs>  
catch(Exception e){e.printStackTrace ();} M(I%QD  
} )G-u;1r
d  
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private void processErrorCode(int nErrorCode) Y#+Ws0wN  
{ S(/^_Y  
System.err.println("Error Code : " + nErrorCode); y}?PyPz  
} [("2=Uz;  
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//停止文件下载 p+0gE5  
public void siteStop() vy` lfbX@  
{ Jp|eKZ  
bStop = true; %Y,Ru)5}  
for(int i=0;i<nStartPos.length;i++) E)wf
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fileSplitterFetch.splitterStop(); PXML1.r$Q  
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} :yTr:FoF  
} ;-_ZWk]  
//负责部分文件的抓取 %gWQ}QF  
**FileSplitterFetch.java YW
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*/ <~aKwSF[wW  
package NetFox; P4.)kK.3q|  
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import java.io.*; Uy*d@vU9c  
import java.net.*; A8-a}0Gh  
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public class FileSplitterFetch extends Thread { Zrj#4E1  
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String sURL; //File URL d[ _@l  
long nStartPos; //File Snippet Start Position 0gHV(L?  
long nEndPos; //File Snippet End Position 'z{
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int nThreadID; //Thread's ID w#ZzmO  
boolean bDownOver = false; //Downing is over r4<As`&  
boolean bStop = false; //Stop identical !b&+2y2i[W  
FileAccessI fileAccessI = null; //File Access interface ,*YmXR-"  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 4S4gK   
{ u /DE  
this.sURL = sURL; q*tGlM@R?  
this.nStartPos = nStart; bZ:xH48MY  
this.nEndPos = nEnd; F1BXu@~e(  
nThreadID = id; Ni|MTE]~  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 y4$$*oai&  
} Xfbr;Jt"<  
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public void run() HF"TS*  
{ IP@3R(DS%  
while(nStartPos < nEndPos && !bStop) U$3DIJVI  
{ 8@LUL)"  
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try{ q+2A>:|  
URL url = new URL(sURL); fE
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); `&'{R<cL  
httpConnection.setRequestProperty("User-Agent","NetFox"); sI h5cT  
String sProperty = "bytes="+nStartPos+"-"; r=SCbv  
httpConnection.setRequestProperty("RANGE",sProperty);
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Utility.log(sProperty); q'4P/2)va  
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InputStream input = httpConnection.getInputStream(); 
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//logResponseHead(httpConnection); <&2<>*/.y  
ob'" ^LO\  
#XB3Wden2  
byte[] b = new byte[1024]; *|y$z+g/  
int nRead; WRwx[[e6z  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) LI&E.(:  
{ 3 S*KjY'@  
nStartPos += fileAccessI.write(b,0,nRead); pKGhNIj$  
//if(nThreadID == 1) O[
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); x*RSD,3  
} nC!]@lA  
i$`o,m#  
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Utility.log("Thread " + nThreadID + " is over!"); r:$*pC&{  
bDownOver = true; m#i4_F=^b  
//nPos = fileAccessI.write (b,0,nRead); xx|D#Z}G  
} |yz o|%]3  
catch(Exception e){e.printStackTrace ();} ;\6@s3  
} 60cQ3.e  
} mEu2@3^E }  
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//打印回应的头信息 =wW M\f`=  
public void logResponseHead(HttpURLConnection con) |=0w_)Fa]  
{ </@5>hx/  
for(int i=1;;i++) x DNu'  
{ @YQ*a4`  
String header=con.getHeaderFieldKey(i); XjP&  
if(header!=null) /#SfgcDt  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); mpCu,l+lo  
Utility.log(header+" : "+con.getHeaderField(header)); ]7>#YKH.  
else []aw;\7}Y  
break; %<+uJ'pj  
} BfCn
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} _`O",Ff  
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public void splitterStop() -mGG:#yP  
{ 0l& '`  
bStop = true; 9<toDg_  
} @$ Nti>  
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} 8_G6X\q};  
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/* US3)+6  
**FileAccess.java 9I2&Vx=DSt  
*//文件访问(定位，写) .-![ ra  
package NetFox; ],[<^=|  
import java.io.*; SZLugyZ2Y  
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public class FileAccessI implements Serializable{ =nc;~u|]  
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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 K(lSR  
RandomAccessFile oSavedFile; OcPgw/ I  
long nPos; H!hd0.  
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wIR"!C>LE  
public FileAccessI() throws IOException reArXmU<u  
{ Y?7GFkIP$  
this("",0); ~av#r=x  
} LAnC8O  
!OQ5AF$  
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public FileAccessI(String sName,long nPos) throws IOException q5hE S  
{ J$5G8<d>  
oSavedFile = new RandomAccessFile(sName,"rw"); ?Js4\X!uJ  
this.nPos = nPos; MBw;+'93qf  
oSavedFile.seek(nPos); vu.?@k@  
} V*fv>f:Yv  
VF";
p^  
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public synchronized int write(byte[] b,int nStart,int nLen) 8#tuB8>  
{ oF]]Pl{W  
int n = -1; _yR_u+
5  
try{ ;|oft-y  
oSavedFile.write(b,nStart,nLen); oqysfLJ  
n = nLen; r-xP6
  
} )*XWe|H_  
catch(IOException e) 94dd )/a  
{ ,%N[FZ`|  
e.printStackTrace (); H25Qx;(dTk  
} CueC![pj  
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return n; <-b9 )>  
} .K(9=yh  
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} "u^v
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/* 3@Fa  
**SiteInfoBean.java <]KQ$8dtD  
*/ trrK6(p  
package NetFox; z_lKq}^~6  
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public class SiteInfoBean { B0)|sH  
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private String sSiteURL; //Site's URL 8q{|nH  
private String sFilePath; //Saved File's Path L[D+=  
private String sFileName; //Saved File's Name {~FPvmj&  
private int nSplitter; //Count of Splited Downloading File k+?gWZ\  
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public SiteInfoBean() 5Rs#{9YE  
{//nSplitter的缺省值为5 N[\J#x!U  
//default value of nSplitter is 5 $57Q g1v  
this("","","",5); -ZSN0Xk  
} /FC HF#yK  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) .81Y/Gad_  
{ F<6(Hw#>  
sSiteURL= sURL; }v|_]   
sFilePath = sPath; \<`oW>  
sFileName = sName; XR7v
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this.nSplitter = nSpiltter; 0&I*)Zt9x  
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} 52Lp_
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public String getSSiteURL() W!O/t^H>  
{
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return sSiteURL; +"BJjxG  
} N*$GP3]  
! M CV@5$  

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public void setSSiteURL(String value) Il*!iX|23<  
{ 'm6bfS^T  
sSiteURL = value; Lp(`m=;O  
} C,eP!_O  
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!DSm[Z1  
public String getSFilePath() S#8)N`  
{ D
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return sFilePath; - QY<o|  
} %!nN<%  
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public void setSFilePath(String value) p o)lN[v  
{
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sFilePath = value; c"lwFr9x7  
} m3pDFI  
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public String getSFileName() xl,% Z~[  
{ 2P8wvNDG  
return sFileName; w5PscEc  
} oNPvksdC;  
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public void setSFileName(String value) i?(cp["7  
{ Q"{Dijc%  
sFileName = value; .(cpYKFX  
} .$}z</#!  
7* Y*_cH5  
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public int getNSplitter() #'>)?]tn  
{ Bx5xtJ|!  
return nSplitter; #9[>  
} +3-5\t`  
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public void setNSplitter(int nCount) ^(C4Q?[2m  
{ VPT?z  
nSplitter = nCount; j?|V
x'  
} `3VI9GmQ  
} >}~[ew  
1irSI,j%z  
]nRf%Vi8g  
/* 57;0,k5Gy  
**Utility.java M_%
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*/ _wb]tE ~g  
package NetFox; l#^?sbG  
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public class Utility { WUz69o be  

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public Utility() *Us}E7/"'  
{ 3$YbEl@#  
0<@['W}G  
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} I|&DXF  
`!I/6d?A  
//线程睡眠 )=K8mt0qob  
public static void sleep(int nSecond) YV|_
y:-  
{ ~%h )G#N  
try{ |?^qsnB  
Thread.sleep(nSecond); A. tGr(r  
} <v'[Wl@hq  
catch(Exception e) q#c+%,Z=C  
{ Nk\ni>Du3  
e.printStackTrace (); ,ps?
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} /"A=Yf  
} ai?J
  
2Ul8<${c{  
//日志 oVHe<zE.  
public static void log(String sMsg) `G:1  
{ P#!gP
3  
System.err.println(sMsg); m5N,
[^-  
} VV$#<D<)  
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public static void log(int sMsg) RiR],Sj  
{ "DvZCf[}  
System.err.println(sMsg); K7JZUS`C!  
} v07A3oj  
} %2I>-0]B  
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%Ul,9qG+  
/* .J @mpJdY  
**TestMethod.java ~PyS;L}  
*/ #U%HGTE0  
package NetFox; .kuNn-$  
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public class TestMethod { nPI$<yW7F  
N3#^Ifn[  
3D@3jyo:  
public TestMethod() 5p~5-_JX  
{ ///xx/weblogic60b2_win.exe G/3T0d+-  
try{ /]J\/Z>  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 9@"pR;X@  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ;Q vQ fV4  
SiteFileFetch fileFetch = new SiteFileFetch(bean); q#8\BOTP |  
fileFetch.start(); L|#0CRiN  
} zq$L[X  
catch(Exception e){e.printStackTrace ();} +\ "NPK@3  
.7Yox1,  
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} @IbZci)1  
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Y$,~"$su|  
public static void main(String[] args) W-r^ME  
{ ^4]=D nd%  
new TestMethod(); V+lS\E.  
} Z5U\>7@&8  
} G^h:#T
  
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