http断点续传简单实现（java)

/* N~v6K}`}  
**SiteFileFetch.java \Z[
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*/ ~KBa-i%o  
package NetFox; zJe KB8  
import java.io.*; G;Li!H  
import java.net.*; Joow{75K  
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public class SiteFileFetch extends Thread { s^h@b!'7  
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SiteInfoBean siteInfoBean = null; //文件信息Bean (2g a:}K  
long[] nStartPos; //开始位置 M3(N!xT  
long[] nEndPos; //结束位置 ON :t"z5  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 fkA+:j~z_  
long nFileLength; //文件长度 @(t3<g  
boolean bFirst = true; //是否第一次取文件 ?Nos;_/  
boolean bStop = false; //停止标志 5'AP:3Gf"  
File tmpFile; //文件下载的临时信息 OW7  
DataOutputStream output; //输出到文件的输出流 <!OBpAq  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 380`>"D  
public SiteFileFetch(SiteInfoBean bean) throws IOException Ds9)e&yYrb  
{ F2"fOS  
siteInfoBean = bean; GEc6;uz<  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); mUYRioNj  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); XkaREE  
if(tmpFile.exists ()) J<$@X JLS  
{ =RoG?gd{R  
bFirst = false; O'<V[Y}6  
read_nPos(); Q]ersA8 V>  
} %w;qu1j  
else {{G)Ry*pb  
{ +7_qg i7:  
nStartPos = new long[bean.getNSplitter()]; "Xq_N4  
nEndPos = new long[bean.getNSplitter()]; As:O|!F  
} *dl hRa  
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} *uvM6F$ut  
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public void run() M\ATT%b:  
{ $0])%   
//获得文件长度 6u[fCGi%  
//分割文件 w"hd_8cO  
//实例FileSplitterFetch (b&g4$!x&5  
//启动FileSplitterFetch线程 YT\`R  
//等待子线程返回 kiTC)S=])  
try{ _$~>O7  
if(bFirst) ).~ "  
{ (3Db}Hnn  
nFileLength = getFileSize(); c%H' jB[  
if(nFileLength == -1) RSX27fb4  
{ 9YzV48su#  
System.err.println("File Length is not known!"); #;[G>-tC  
} [vg&E )V  
else if(nFileLength == -2) @N*|w Kc+  
{ TnrBHaxbo4  
System.err.println("File is not access!"); ;mQj2Bwr  
} A5<t>6Y  
else _CwTe=K}  
{ atuqo3  
for(int i=0;i<nStartPos.length;i++) 9&+]YYCS-  
{ K<S3gb?0  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); n`Q@<op  
} !eX0Q 2  
for(int i=0;i<nEndPos.length-1;i++) O1c%XwMn^  
{
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nEndPos = nStartPos[i+1]; GZ%vFje_ K  
} GppCrQ%Ra|  
nEndPos[nEndPos.length-1] = nFileLength; vDjH $ U  
} ;ALWL~Xm  
} %:3XYO.w-  
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//启动子线程 f%G\'q]#F  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; u`MMK4 %  
for(int i=0;i<nStartPos.length;i++) hD6
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{ dNACE*g;q  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), lF}[ YL  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), nY'V,v[F  
nStartPos,nEndPos,i); VfU"%0x  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (r|m&/  
fileSplitterFetch.start(); jJ$\WUQ.  
} QiK>]xJ'  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), qTsy'y;Z  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); zdN[Uc+1Bd  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", b:==:d:0s  
nEndPos = " + nFileLength); z.Cj%N  
// fileSplitterFetch[nPos.length-1].start(); o'2eSm0H  
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//等待子线程结束 =p5D

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//int count = 0; ]#:WL)@  
//是否结束while循环 mxNd_{n  
boolean breakWhile = false; K%q5:9m  
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while(!bStop) ,i:?c  
{ ,#Z%0NLe  
write_nPos(); :_e[xB=Yy  
Utility.sleep(500); (W}F\P  
breakWhile = true; WZQ2Mi<&1'  
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for(int i=0;i<nStartPos.length;i++) )Q2IYCj{  
{ z,,"yVk`,  
if(!fileSplitterFetch.bDownOver) <KMCNCU\+  
{ .}==p
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breakWhile = false; Q'OtXs 80  
break; EBy7wU`S  
} /U;j-m&   
} U,g8:M xHK  
if(breakWhile) U1 _"D+XB  
break; 2e_ Di(us  
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//count++; X1#Ar)  
//if(count>4) s~M$Wo8  
// siteStop(); 8~Cmn%  
} u)@:V)z  
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System.err.println("文件下载结束！"); [qc1 V%g  
} ~F"S]  
catch(Exception e){e.printStackTrace ();} X4%uY  
} ]?6wU-a  
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//获得文件长度 g5y+F
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public long getFileSize() Z^kE]Ir#EV  
{ A8-[EBkK  
int nFileLength = -1; 8T1`9IT
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try{ Spn[:u@  
URL url = new URL(siteInfoBean.getSSiteURL()); orjtwF>^  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); p9"dm{  
httpConnection.setRequestProperty("User-Agent","NetFox"); UT;%I_i!'  
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int responseCode=httpConnection.getResponseCode(); x?S86,RW  
if(responseCode>=400) FX!KX/OE)  
{ ~.T|n =  
processErrorCode(responseCode); w)7y{ya$  
return -2; //-2 represent access is error ;W- A2g  
} 2 7)IfE  
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String sHeader; "
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for(int i=1;;i++) G_+/ e]P  
{ B_[efM<R$  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); $gr>Y2i  
//Utility.log(in.readLine()); pS$9mzY  
sHeader=httpConnection.getHeaderFieldKey(i); ,C,nN
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if(sHeader!=null) NK0'\~7&  
{ 7r;16"  
if(sHeader.equals("Content-Length")) J4+K
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{ ]'5Xjcx  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); KElEGW  
break; d*8*9CpO:  
} eha|cAq  
} +u|"q+p  
else Ar<5UnT  
break; NtM>`5
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} 30vxOkS
 
} @&?(XY 'M%  
catch(IOException e){e.printStackTrace ();} }u
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catch(Exception e){e.printStackTrace ();} Y%;J/4dd  
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Utility.log(nFileLength); e]VW\6J&  
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return nFileLength; 7(}'
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} Y
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//保存下载信息（文件指针位置） &|x7T<,)  
private void write_nPos() PA'&]piPl:  
{  x+cL(R  
try{ 5n?P}kca)  
output = new DataOutputStream(new FileOutputStream(tmpFile)); [W3X$r~-  
output.writeInt(nStartPos.length); pg%(6dqK4  
for(int i=0;i<nStartPos.length;i++) j!agD_J  
{ N>(w+h+  
// output.writeLong(nPos); glLVT i  
output.writeLong(fileSplitterFetch.nStartPos); W{-g?)Tou  
output.writeLong(fileSplitterFetch.nEndPos); lqfTF  
} U)G.Bst  
output.close(); e*Wk;D&  
} b- - tl@H  
catch(IOException e){e.printStackTrace ();} V;eaQ  
catch(Exception e){e.printStackTrace ();} -6+7&.A+  
} 5, $6mU#=  
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//读取保存的下载信息（文件指针位置） Po58@g  
private void read_nPos() t#"0^$l=  
{ ( unmf,y  
try{ /<)Vd  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); KRL.TLgq)  
int nCount = input.readInt(); j{lurb)y  
nStartPos = new long[nCount]; %M`48TW)  
nEndPos = new long[nCount]; "}v.>L<P  
for(int i=0;i<nStartPos.length;i++) 0g[ %)C  
{ "AUSgVE+h  
nStartPos = input.readLong(); u9~5U9]O%6  
nEndPos = input.readLong(); A1/@KC"&{G  
} :&wb+tV  
input.close(); S46aUkW.  
} O[VY|.MEk  
catch(IOException e){e.printStackTrace ();} O&<p 8
 
catch(Exception e){e.printStackTrace ();} ]L~NYe9  
} {_N9<i{T  
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private void processErrorCode(int nErrorCode) wj6u,+  
{ Hk*1Wrs*  
System.err.println("Error Code : " + nErrorCode); e' M&Eh  
} Imv#7{ndq  
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//停止文件下载 %g@?.YxjT  
public void siteStop() 7 0?iZIK _  
{ WnG2\(U  
bStop = true; qm$(_]R~`  
for(int i=0;i<nStartPos.length;i++) $A?9U}V#^  
fileSplitterFetch.splitterStop(); ,jRAVt+{N  
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} o*)Sg6Yk  
} 8GP17j  
//负责部分文件的抓取 $~1vXe  
**FileSplitterFetch.java ketp9}u  
*/ bVzi^R"  
package NetFox; }O*`I(  
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import java.io.*; KFbB}oId  
import java.net.*; 3'.@aMA@  
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public class FileSplitterFetch extends Thread { #B5,k|"/,M  
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String sURL; //File URL xoo,}EY  
long nStartPos; //File Snippet Start Position K\2{SjL:B  
long nEndPos; //File Snippet End Position UiG/Rn  
int nThreadID; //Thread's ID ZMQ=D!kT  
boolean bDownOver = false; //Downing is over r>fGj\#R =  
boolean bStop = false; //Stop identical GS>[A b+  
FileAccessI fileAccessI = null; //File Access interface Jx5`0?  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ;+wB!/k,  
{ L"&T3i  
this.sURL = sURL; e>z"{ u(F0  
this.nStartPos = nStart; rk8pL[|  
this.nEndPos = nEnd; M<Wi:r:  
nThreadID = id; I&+.IK_  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 _4N.]jr5  
} N_T5sZ\  
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public void run() g.&B8e  
{ C{bxPILw  
while(nStartPos < nEndPos && !bStop) ~^obf(N`  
{ Y]([K.I=  
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try{ QH-CZ6M  
URL url = new URL(sURL); !Axe}RD'  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ,LA'^I?  
httpConnection.setRequestProperty("User-Agent","NetFox"); aLh(8;$  
String sProperty = "bytes="+nStartPos+"-"; tLOGj?/r  
httpConnection.setRequestProperty("RANGE",sProperty); )P(S:x'b0  
Utility.log(sProperty); dq '2y  
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InputStream input = httpConnection.getInputStream(); &|XgWZS5  
//logResponseHead(httpConnection); iW6O9~  
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byte[] b = new byte[1024]; J,Ki2'=  
int nRead; STnMBz7  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ?r !kKMZ  
{ ]S%_&ZMCM  
nStartPos += fileAccessI.write(b,0,nRead); vNw(hT5750  
//if(nThreadID == 1) lWc[Q1  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); KF'fg R  
} \)dp  
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Utility.log("Thread " + nThreadID + " is over!"); 0hoMf=bb$  
bDownOver = true; ^P9mJ:  
//nPos = fileAccessI.write (b,0,nRead); dLYM )-H`>  
} sR/Yv  
catch(Exception e){e.printStackTrace ();} T)e2IXGN  
} !U?C
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} bR7tmJ[)Z  
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//打印回应的头信息 1#N`elm  
public void logResponseHead(HttpURLConnection con) i]<@  
{ l0G{{R0Y  
for(int i=1;;i++) @rT$}O1?`  
{ (.$$U3\  
String header=con.getHeaderFieldKey(i); ky|kg@n{  
if(header!=null) WblH}  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); x9F*$G  
Utility.log(header+" : "+con.getHeaderField(header)); Ly(
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else
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break; t?&;   
} =A5i84y.2u  
} 7d.H8C2  
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public void splitterStop() y3(~8n  
{ z>+CMH5L)  
bStop = true; !QdX+y<re  
} T^eD
  
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} b6;MTz*k>  
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/* WMKxGZg"  
**FileAccess.java rk%pA-P2  
*//文件访问(定位，写) r!w4Br0  
package NetFox; ?ZTA3mV?+  
import java.io.*; @
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public class FileAccessI implements Serializable{ ]hlQU%&  
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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 7&etnQJ{  
RandomAccessFile oSavedFile; YA+R!t:F{  
long nPos; b!-=L&V  
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public FileAccessI() throws IOException tHqa%  
{ dM}c-=w`  
this("",0); ;<o?JM  
} _TdH6[9  
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public FileAccessI(String sName,long nPos) throws IOException Z9MU%*N  
{ Le-t<6i-V#  
oSavedFile = new RandomAccessFile(sName,"rw"); wg k[_i  
this.nPos = nPos; 3 q
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oSavedFile.seek(nPos); ,y0 &E8Z  
} kxrYA|x  
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public synchronized int write(byte[] b,int nStart,int nLen) ,ZYPffu<*  
{ 5l,Lp'k  
int n = -1; wKcuIc$  
try{ {Gh9(0,B?  
oSavedFile.write(b,nStart,nLen); CE (zt  
n = nLen; lV./K;\T  
} ijcF[bmE  
catch(IOException e) K{Nj-Rqd  
{ TrgKl2xfx  
e.printStackTrace (); m1K4_a)^[  
} Z6So5r%wZ  
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return n; o*~=NoR  
} O<AGAD  
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} _/ 5  
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/* [\0>@j}Z  
**SiteInfoBean.java );S8`V  
*/ @d8Nr:  
package NetFox; 2#qcYU  
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public class SiteInfoBean { y(a>Y! dgU  
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private String sSiteURL; //Site's URL vwAhNw2-  
private String sFilePath; //Saved File's Path i}f"'KW  
private String sFileName; //Saved File's Name O#{`Fj`  
private int nSplitter; //Count of Splited Downloading File GAs.?JHd  
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public SiteInfoBean() 2h@&yW2j  
{//nSplitter的缺省值为5 A*|\E:fo  
//default value of nSplitter is 5 3
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this("","","",5); EIpz-"S  
} NTGWI$  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) RA){\~@wC  
{ z X+i2,  
sSiteURL= sURL; >%N,F`^3  
sFilePath = sPath; g&_f%hx?  
sFileName = sName; xMpgXB!'  
this.nSplitter = nSpiltter; 4qd(a)NdY  
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} 6@:<62!;  
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public String getSSiteURL() K|D1  
{ ^@Qc!(P  
return sSiteURL; p9MJa[}V  
} '!MKZKer  
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public void setSSiteURL(String value) qd'Z|'j  
{ ts,V+cEA  
sSiteURL = value; *
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} kf95)iLo  
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public String getSFilePath() |WT]s B0Eq  
{ & \C1QkI  
return sFilePath; xNRMI!yv   
} `O%
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public void setSFilePath(String value) aM_O0Rn==  
{ ^ME'D  
sFilePath = value; "F Etl(  
} .rX,*|1x  
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public String getSFileName() IF6-VFY:6  
{ =L?2[a$2;  
return sFileName; ^oE#;aS  
} u2[L^]|  
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public void setSFileName(String value) C/9]TkX}q  
{ CZ{7?:^f  
sFileName = value; ^/}&z  
} *.T?#H  
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public int getNSplitter() ]8'PLsS9<w  
{ R. vV
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return nSplitter; mGJRCK_  
} 43O5|8o  
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public void setNSplitter(int nCount) h7o.RRhK  
{ $
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nSplitter = nCount; ekmWYQ ~  
} O*W<za;  
} sN#ju5  
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/* Y zmMF  
**Utility.java *O_^C  
*/ =4V SbOlZ  
package NetFox; Imq-5To#  
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public class Utility { OEC/'QOae  
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public Utility() 4:/^.:  
{ <z>oY2%  
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} #l7v|)9v  
#l3)3k*;  
//线程睡眠 t`>Z#=cl\  
public static void sleep(int nSecond) h ^s8LE3  
{ Htln <N  
try{ Z_Y'#5o#  
Thread.sleep(nSecond); x($Djx  
} c& bms)Jwa  
catch(Exception e) NSH4 @x  
{ (Nv-wU  
e.printStackTrace (); a;M{-G  
} <^_crJONom  
} BBv+*jj  
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//日志 %qTIT?6'  
public static void log(String sMsg) %H,s~IU  
{ n=AcN  
System.err.println(sMsg); x}
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} %H2ios[UO  
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public static void log(int sMsg) a(ITv roM/  
{ `Pc<0*`a  
System.err.println(sMsg); -5ZmIlL.S  
} CjP<'0gT  
} {<Gp5j  
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/* uoeZb=<  
**TestMethod.java Zj'%c2U_  
*/ jX(hBnGW  
package NetFox; Q~VM.G  
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public class TestMethod { #8yo9g6  
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public TestMethod() {uoF5|O6K  
{ ///xx/weblogic60b2_win.exe k0K$OX
*:e  
try{ *X
2PT(e[  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ' BS.:^  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); @z{SDM  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 7bihP@I!  
fileFetch.start(); k%i.B  
}  gu[
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catch(Exception e){e.printStackTrace ();} "wTCO1  
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;  
} 3IlVSR^py  
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public static void main(String[] args) ?X@[ibH6  
{ H?J:_1  
new TestMethod(); o,dp{+({  
} 9&AO  
} Ohp@ZJ!a?  
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