http断点续传简单实现（java)

/* U>IllNd  
**SiteFileFetch.java |[CsLn;  
*/  M
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package NetFox; iN"kv   
import java.io.*; 1Zx|
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import java.net.*; 8s/gjEwA  
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public class SiteFileFetch extends Thread { -X'HZ\)  
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SiteInfoBean siteInfoBean = null; //文件信息Bean OKNA36cU'  
long[] nStartPos; //开始位置 h8Q+fHDYv  
long[] nEndPos; //结束位置 x9Y1v1!5Pu  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 U[*VNJSp  
long nFileLength; //文件长度 AV Gu*  
boolean bFirst = true; //是否第一次取文件 mM!'~{r[-  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 8*!<,k="9  
DataOutputStream output; //输出到文件的输出流 ];Z)=y,vM  
u=z$**M^  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） !Y>lAxd  
public SiteFileFetch(SiteInfoBean bean) throws IOException Yz=(zj  
{ X^ckTIdR  
siteInfoBean = bean; t.$3?"60~  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 9un]}7^  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); dF:@BEo  
if(tmpFile.exists ()) Umjt~K^Z  
{ k"&loh  
bFirst = false; /:3:Ky3  
read_nPos(); A-^[4&rb  
} n0F.Um  
else )uC],CbW{  
{ px %xoY  
nStartPos = new long[bean.getNSplitter()]; k!3X4;F!_  
nEndPos = new long[bean.getNSplitter()]; 8]skAh  
} M(|Qvh{Q6  
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} d9>*a$x;/  
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public void run() hr_ 5D  
{ s0uI;WMg  
//获得文件长度 mbB,j~;^6H  
//分割文件 x=T`i-M  
//实例FileSplitterFetch :Rv?>I j  
//启动FileSplitterFetch线程 gNF8&T  
//等待子线程返回 tvXoF;Yq  
try{ 4 AZ~<e\  
if(bFirst) 9pUvw_9MY  
{ oFM\L^Y?$$  
nFileLength = getFileSize(); %E#OUo[y/  
if(nFileLength == -1) IhnHNY]<g  
{ 5OeTOI()&5  
System.err.println("File Length is not known!"); A}WRpsA9  
} nfpkWyIu{  
else if(nFileLength == -2) q9
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{ N`XJA-
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System.err.println("File is not access!"); KwK[)Cvv  
} .w2QiJ  
else @)s;u}H  
{ arJ4^ d  
for(int i=0;i<nStartPos.length;i++) rE0?R(_  
{ ^,u0kMG5l  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); L08>9tf`  
} Ay)q %:qx  
for(int i=0;i<nEndPos.length-1;i++) Fx,08  
{ [M>Md-pj  
nEndPos = nStartPos[i+1]; hoY.2 B_  
} >dKK [E/[d  
nEndPos[nEndPos.length-1] = nFileLength; I@Zd<Rn  
} PN9^ sLx=  
} "<o[X
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4;"^1 $  
- s[=$pDU  
//启动子线程 !`5[(lm  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; F*V<L   
for(int i=0;i<nStartPos.length;i++) OS8 ^mC  
{ r/v'h@  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), O@JgVdgf  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), #oRm-yDr  
nStartPos,nEndPos,i); ' >(])Oq,  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Ow7NOhw  
fileSplitterFetch.start(); K&FGTS,  
} C!Cg.^;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), *9:oTN  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Eu/~4:XN  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", yMdEH-?/  
nEndPos = " + nFileLength); x._IP,vRx^  
// fileSplitterFetch[nPos.length-1].start(); ?^Sk17G  
XL[/)lX{  
gcYx-gA}  
//等待子线程结束 _&S?uz m  
//int count = 0;
mk>L:+  
//是否结束while循环 _XT],"  
boolean breakWhile = false; O%)@> 5#S  
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while(!bStop) Rz}?@zh_8  
{ gfE<XrG  
write_nPos(); M99#\0=/  
Utility.sleep(500); >Gbj1>C}  
breakWhile = true; 8 vNgePn  
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for(int i=0;i<nStartPos.length;i++) -q7A\8C  
{ QS2J271E}  
if(!fileSplitterFetch.bDownOver) (H*-b4]/  
{ $ tf;\R  
breakWhile = false; ;9r Z{'i+|  
break; 9tZ)#@\  
} xt]Z{:.  
} SNP.n))   
if(breakWhile) f.V;Hl,  
break; v+-f pl&  
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//count++; UnNvlkjq9  
//if(count>4) Ke[doQ#c  
// siteStop(); f])?Gw  
} kTQ:k }%B  
)/k0*:OMyO  
R`=3lY;  
System.err.println("文件下载结束！"); 0?uX}8w  
} 'G6TSl  
catch(Exception e){e.printStackTrace ();} !mFo:nQ)}  
} G%)?jg@EA  
n+@}8;oeP  
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//获得文件长度 '|^LNAx  
public long getFileSize() $w%oLI@kl  
{ q0WW^jwQ  
int nFileLength = -1; J*6I@_{/U  
try{ 5A1oZ+C#  
URL url = new URL(siteInfoBean.getSSiteURL()); O$x-&pW`g  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); iU^ 4a  
httpConnection.setRequestProperty("User-Agent","NetFox"); m}.ru)^p  
ANSvZqKh  
}yqRz6=YB  
int responseCode=httpConnection.getResponseCode(); 47I:o9E  
if(responseCode>=400) O<4i)Lx2  
{ tW5\Ktjno  
processErrorCode(responseCode); "_+X#P x  
return -2; //-2 represent access is error
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} g$VcT\X  
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String sHeader; K-wjQ|*1  
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for(int i=1;;i++) (Br$(XJoK}  
{ FcIH<_r  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); t )Z2"_5  
//Utility.log(in.readLine()); T~$ePVk>L  
sHeader=httpConnection.getHeaderFieldKey(i); :w_F<2d0 0  
if(sHeader!=null) 6bnAVTL5  
{ Af=%5%  
if(sHeader.equals("Content-Length")) "b%hAdR  
{ OdQ>h$ gZ  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); )xQxc.  
break; A`(p6 H"s  
} )$q<"t\#P#  
} qh$D;t1=  
else 2BH>TmS  
break; 7tAWPSwf  
} w:FH2*  
} N=D Ynz_~  
catch(IOException e){e.printStackTrace ();} +lJuF/sS8m  
catch(Exception e){e.printStackTrace ();} $Fz/&;KX!  
z+" :,#  
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Utility.log(nFileLength); _z
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2?t(%uf]  
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return nFileLength; #!#V!^ o  
} ibzYY"D:  
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} Q1$v~  
//保存下载信息（文件指针位置） &8"a7$  
private void write_nPos() \(T;@r  
{ ~$r^Ur!E\  
try{ 9Z*`{  
output = new DataOutputStream(new FileOutputStream(tmpFile)); RB/[(4  
output.writeInt(nStartPos.length); 6./&l9{h+  
for(int i=0;i<nStartPos.length;i++) bG^eP:r  
{ `m2F.^qrr  
// output.writeLong(nPos); 2IjqTL  
output.writeLong(fileSplitterFetch.nStartPos); @1n0<V/  
output.writeLong(fileSplitterFetch.nEndPos); F!]UaEmV  
} ac+7D:X  
output.close(); ls*^3^O  
} o\|dm."f  
catch(IOException e){e.printStackTrace ();} twgU ru  
catch(Exception e){e.printStackTrace ();} =m}{g/Bk  
} :\80*[=;Z  
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W@wT,yJ8@  
//读取保存的下载信息（文件指针位置） wCmwH=
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private void read_nPos() *3"C"4S  
{ WDzov9o
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try{ R63"j\0  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); D<xPx  
int nCount = input.readInt(); EXJ>Z  
nStartPos = new long[nCount]; Mqc[IAcd]  
nEndPos = new long[nCount]; a*SJHBB  
for(int i=0;i<nStartPos.length;i++) P\2QH@p@t  
{ Y!POUMA }A  
nStartPos = input.readLong(); U +mx@C_  
nEndPos = input.readLong(); a S<JsB  
} ORtl~V'  
input.close(); ^S<
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} 3N]pN<3@  
catch(IOException e){e.printStackTrace ();} :eIBK  
catch(Exception e){e.printStackTrace ();} $u3N',&  
} j,1,;  
0.@/I}R[  
8:t-I]dzk  
private void processErrorCode(int nErrorCode) JpuW !I  
{ Q;aZpi-E"  
System.err.println("Error Code : " + nErrorCode); 3Ji,n;QLm  
} /u #9M {  

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//停止文件下载 <M$hj6.tn  
public void siteStop() }*R"yp  
{ ?<nz2 piP,  
bStop = true; ,/d-o;W  
for(int i=0;i<nStartPos.length;i++) Z&.FJZUP  
fileSplitterFetch.splitterStop(); BV!Kiw  
*K+*0_  
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} s#d# *pgzh  
} g` h>:
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//负责部分文件的抓取 Xp{gh@#dr  
**FileSplitterFetch.java VWMCbg>R  
*/ @x
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package NetFox; G+%ZN  
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import java.io.*; Q`//
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import java.net.*; SA/0Z=  
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public class FileSplitterFetch extends Thread { (=PnLP  
*uv\V@0  
KK] >0QAY  
String sURL; //File URL sP+S86 u  
long nStartPos; //File Snippet Start Position EAq >v t83  
long nEndPos; //File Snippet End Position Zv-6H*zM6  
int nThreadID; //Thread's ID L9kSeBt  
boolean bDownOver = false; //Downing is over Lte\;Se.tu  
boolean bStop = false; //Stop identical N\Hd3Om  
FileAccessI fileAccessI = null; //File Access interface CY7REF  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException }YSH8d  
{ 3(}?f  
this.sURL = sURL; 4({=(O  
this.nStartPos = nStart; h5Z\9`f[  
this.nEndPos = nEnd; $jzk4V  
nThreadID = id; ~j4=PT  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Bo0y"W[+  
} l%U9g  
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public void run() wXZ-%,R-D  
{ /J6CSk  
while(nStartPos < nEndPos && !bStop) +X?jf.4  
{ ~Ep
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try{ JBYQ7SsAS0  
URL url = new URL(sURL); m:^@AR1%d  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _9-Ajv  
httpConnection.setRequestProperty("User-Agent","NetFox"); "d#s|_n,d)  
String sProperty = "bytes="+nStartPos+"-"; :{AN@zC0\  
httpConnection.setRequestProperty("RANGE",sProperty);
8jZYy!  
Utility.log(sProperty); 0hv[
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InputStream input = httpConnection.getInputStream(); q"cFw${  
//logResponseHead(httpConnection); =?2y <B  
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byte[] b = new byte[1024]; P``hw=L  
int nRead; e,x@?L*  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) hw7_8pAbh  
{ u,pm\  
nStartPos += fileAccessI.write(b,0,nRead); Kzm_AHA)  
//if(nThreadID == 1) ::R^ w"  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); z~BB|-kp1  
} $-y+97  
*K)v&}uw  
J8%|Gd0#4  
Utility.log("Thread " + nThreadID + " is over!"); w iq{Jo#  
bDownOver = true; M{S7ia"s  
//nPos = fileAccessI.write (b,0,nRead); SN+Bmdup  
} y>OZ<!`  
catch(Exception e){e.printStackTrace ();} Zu$f[U)X  
} T'V(%\w  
} %pt$S~j  
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//打印回应的头信息 ceOjuzY  
public void logResponseHead(HttpURLConnection con) cC[n~OV  
{ cU>&E*wD  
for(int i=1;;i++) 79V5{2Y*U  
{ KZE.}8^%D  
String header=con.getHeaderFieldKey(i); UVLcR  
if(header!=null) WY,t> 1c  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); /;0>*
ft4  
Utility.log(header+" : "+con.getHeaderField(header)); h<M7[p=  
else PHXP1)^}S  
break; 7L]?)2=  
} yjO7/<2  
} !$?@;}=  
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public void splitterStop() g-^m\>B  
{ IX(yajc[~M  
bStop = true; -7$'* V9$  
} S3'g(+S  
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} 7`/qL "  
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/* gB(W`:[  
**FileAccess.java *\WI!%  
*//文件访问(定位，写) _pGviGR  
package NetFox; Vr1
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import java.io.*; nnNg^<[k3  
qtN29[x  
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public class FileAccessI implements Serializable{ lnWiE}F  
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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 Uq.~3V+u  
RandomAccessFile oSavedFile; LwPM7S~ *  
long nPos; gJxVU41  
ss{=::#  
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public FileAccessI() throws IOException \#jDQ  
{ .^S78hr]n  
this("",0); BznA)EK?@  
} kV3j}C"  
S1`0d9ds#  
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public FileAccessI(String sName,long nPos) throws IOException GKhwn&qCKb  
{ xg^^@o  
oSavedFile = new RandomAccessFile(sName,"rw"); Oc9>F\]_m  
this.nPos = nPos; TY\"@(Q|G  
oSavedFile.seek(nPos); ~&lJT  
} /7@2Qc2  
(I ds<n"  
XHM"agrhSQ  
public synchronized int write(byte[] b,int nStart,int nLen) $cK B+}  
{ w00\1'-Kz  
int n = -1; (OcNC/9  
try{ p}DF$k%`  
oSavedFile.write(b,nStart,nLen); /_OZ1jX  
n = nLen; >MWpYp  
} Fg\| e%  
catch(IOException e) ;u};&sm  
{ %)Uvf`Xhh4  
e.printStackTrace (); H\+c'$  
} B=bI'S8\  
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return n; JX/4=..  
} ,PMb9O\B  
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} px}7If  
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/* @ZkAul0@  
**SiteInfoBean.java
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*/ nN`Z0?  
package NetFox; y^QYlZO  
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q= yZx)  
public class SiteInfoBean { y+";  
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private String sSiteURL; //Site's URL B3>Uba*-)}  
private String sFilePath; //Saved File's Path Ku/H=  
private String sFileName; //Saved File's Name ~0F9x9V  
private int nSplitter; //Count of Splited Downloading File >1r[]&8  
8PoH
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?z@v3(b[  
public SiteInfoBean() iRUR4Zs  
{//nSplitter的缺省值为5 (~7m"?  
//default value of nSplitter is 5 yC'hwoQ`  
this("","","",5); >'ksXA4b  
} l$-=Pqb  
r
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i.&Kpw9;m  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Q"_T2fl]vP  
{ D/S>w(=  
sSiteURL= sURL; fVH*dX'Jz  
sFilePath = sPath; m@G<ZCMZ  
sFileName = sName; sb}K%-  
this.nSplitter = nSpiltter; <+T\F;   
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} "%oH@ =  
~U"by_  
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public String getSSiteURL() .'^6QST  
{ .DDg%z  
return sSiteURL; ]pOYVf *$  
} S2rEy2\}:  
ka5#<J7<p  
?kL|>1TY  
public void setSSiteURL(String value) x|@1wQ"6  
{ n|70x5Z?}J  
sSiteURL = value; L_THU4^j  
}  xFBh?  
{{V;:+62  
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public String getSFilePath() u}K5/hC  
{ eJU;*] xfH  
return sFilePath; !,cQ'*<W8-  
} bz,Da  
IL~]m?'V(  
)XLj[6j0  
public void setSFilePath(String value) <|{L
[  
{ e[x?6He,$  
sFilePath = value; #4P8
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} ZYE' C  
&`9j)3^J.  
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public String getSFileName() 3R5K}ZBi%  
{ !oZQ2z~  
return sFileName; UWQtvQ f  
} [Ja)<!]<  
zP_]  
kQ@gO[hS  
public void setSFileName(String value) oR*ztM  
{ J.1O/Pw!.a  
sFileName = value; <+V-k|  
} rHvF%o  
B4`2.yRis  
2>F
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public int getNSplitter() FoE|Js  
{ ,"~WkLI~\t  
return nSplitter; K@B" ]6  
} :W~6F*A  
L ;6b+I  
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public void setNSplitter(int nCount) $z*@2Non  
{ +T9Q_e*  
nSplitter = nCount; H5~1g6b@  
} he"L*p*H  
} `,+#!)  
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b)N[[
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/* Sa L"!uAk  
**Utility.java b3}Q#Y\G  
*/ 85'nXYN{d  
package NetFox; !{;[xXK4M  
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public class Utility { ^7.XGWQ)-  
n
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cgyp5\*>+  
public Utility() 4CLsY n?  
{ ~8TF*3[}[  
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-LTKpN`[@  
} K}x_nW  
_g[-=y{Bb  
//线程睡眠 y,Jh@n';|  
public static void sleep(int nSecond) +]c/&Xo!  
{ N>0LQ MI  
try{ zCt\o  
Thread.sleep(nSecond); :}Ok$^5s  
} pE2QnNr'  
catch(Exception e) ,of]J|  
{ [>f]@>  
e.printStackTrace (); t0q_>T-kt  
} ND5$bq Nu?  
} Ql8bt77eI-  
V>Fesm"aq  
//日志 #n3ykzoqIX  
public static void log(String sMsg) GX }q9  
{ xST4}Mb^f  
System.err.println(sMsg); dy2rkV.z  
} [[WF0q  
_1aGtX|W  
g
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public static void log(int sMsg) IxOc':/jY  
{ 6V1:qp/6  
System.err.println(sMsg); )T1iN(Z  
} !77NG4B  
} &$=!dA  
_7"5wB?|+  
'H|~u&?  
/* bAEg$A  
**TestMethod.java 5dl,co{q  
*/  Q=#I9-  
package NetFox; ?qmp_2:WU  
SJk>Jt=  
)*|(i]  
public class TestMethod { 6S1m<aH6  
k_ Y~;P@  
P|xG\3@Z  
public TestMethod() fPqr6OYz  
{ ///xx/weblogic60b2_win.exe Q`ME@vz  
try{ c?E{fD"Fc3  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); lr~0p
L  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); eKG2*CV  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 8Lz]Z h=ZU  
fileFetch.start(); O=}g4c  
} p?# pT}1  
catch(Exception e){e.printStackTrace ();} Fky?\ec  
94/BG0  
ZVih=Y-w  
} 5l{Ts04k%  
S,{tV=&m]  
mJ5H=&Z  
public static void main(String[] args) * F4UAQzYb  
{ fCw*$:O  
new TestMethod(); j:,9%tg  
} h8{(KRa6  
} ezm&]F`  
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