http断点续传简单实现（java)

/* t & 5s.  
**SiteFileFetch.java 1.a:iweN  
*/ tA K=W$r  
package NetFox; ip*UujmNyR  
import java.io.*; cs]3Rp^g  
import java.net.*; ]TsmWob  
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public class SiteFileFetch extends Thread { 4&B|rf  
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SiteInfoBean siteInfoBean = null; //文件信息Bean tz%H1`  
long[] nStartPos; //开始位置 `Z (`  
long[] nEndPos; //结束位置 Ja%isIdh  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Q+E)_5_sA  
long nFileLength; //文件长度 ~A*$+c(  
boolean bFirst = true; //是否第一次取文件 z+nq<%"'  
boolean bStop = false; //停止标志 SCq3Kh  
File tmpFile; //文件下载的临时信息 ZVCa0Km  
DataOutputStream output; //输出到文件的输出流 b.xG'  
//^{u[lr  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Lo +H&-  
public SiteFileFetch(SiteInfoBean bean) throws IOException 
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{ }wGy#!CSza  
siteInfoBean = bean; ESkhC
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); [iN\R+:  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); #| m*
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if(tmpFile.exists ()) JvtbGPz  
{ wUzMB]w  
bFirst = false; 4/&.N]  
read_nPos(); 3u=>Y^wu  
} 8oP"?ew#  
else x\5\KGw16  
{ %lGg}9k'  
nStartPos = new long[bean.getNSplitter()]; TnPx.mwK\  
nEndPos = new long[bean.getNSplitter()]; 5^36nEoA(  
} F\+!\b*lP  
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} :j;_Xw  
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public void run() lZD"7om  
{ 5g phza  
//获得文件长度 PtOYlZTe?  
//分割文件 2| ERif;)  
//实例FileSplitterFetch -p20UP 1I  
//启动FileSplitterFetch线程 RG`eNRTQ%  
//等待子线程返回 C33=<r[;N<  
try{ xx[l#+:c  
if(bFirst) bm(.(0MI  
{ }[ByN).  
nFileLength = getFileSize(); p+:MZP -%(  
if(nFileLength == -1) J-~:W~Qx4N  
{ h.aXW]]}(P  
System.err.println("File Length is not known!"); S6c>D&Q  
} U5H5QW+  
else if(nFileLength == -2) qmbhx9V   
{ r} a,  
System.err.println("File is not access!"); +J:wAmY4  
} z;EDyd,O>  
else TiSV`V
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{ ??g = `yH  
for(int i=0;i<nStartPos.length;i++) "'U]4Z%q!  
{ ~P+;_  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 5Fa/Q>N  
} -
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for(int i=0;i<nEndPos.length-1;i++) ~@'DYZb- H  
{ jN sM&s,  
nEndPos = nStartPos[i+1]; w#RfD  
} Dmn{ppfyb  
nEndPos[nEndPos.length-1] = nFileLength; ]{pH,vk-  
} 7^Y`'~Y^  
} }j|YX&`p  
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r?=3TA
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//启动子线程 nbU?:=P  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; jGOE CKP  
for(int i=0;i<nStartPos.length;i++) 4Kn)5>  
{ :&$WWv  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), wRQMuFGY  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), VJ|80?4h  
nStartPos,nEndPos,i); DM*u;t{i  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); a |0f B4G  
fileSplitterFetch.start(); \.{ZgL5"  
} b@)nB  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #e$vv!&}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); *uvE`4V^Jg  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", )F%zT[Auph  
nEndPos = " + nFileLength); !+ ??3-q  
// fileSplitterFetch[nPos.length-1].start(); vN`JP`IBx  
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//等待子线程结束 ?Yh
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//int count = 0; 8\e8$
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//是否结束while循环 (^LR9 CW  
boolean breakWhile = false; RJA#cv~f  
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while(!bStop) ?bl9e&
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{ !v]~ut !p  
write_nPos(); _Wo(;'.  
Utility.sleep(500); j9$kaEf  
breakWhile = true; fZrB!\Q  
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for(int i=0;i<nStartPos.length;i++) e><,WM,e
 
{ -n`2>L1  
if(!fileSplitterFetch.bDownOver) .7MLgC;  
{ iLJBiZ+  
breakWhile = false; Ox"SQ`nSj'  
break; =
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} r*W&SU9Z  
} ,PZ[CX;H@  
if(breakWhile) ]gB:ht  
break; , @dhJ8/  
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//count++; !9.`zW"40  
//if(count>4) ;2iDa  
// siteStop(); SSa0x9T  
} jMQ7^(9-  
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System.err.println("文件下载结束！"); t[b@P<F  
} aq%i:};  
catch(Exception e){e.printStackTrace ();} iGsD!2  
} )TyI~5>;  
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//获得文件长度 YfU6mQ  
public long getFileSize() WOuk> /  
{ F48W8'un  
int nFileLength = -1; 9Gk#2  
try{ -v62 s  
URL url = new URL(siteInfoBean.getSSiteURL()); _f<#+*y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 55vI^SSA  
httpConnection.setRequestProperty("User-Agent","NetFox"); hC...tk  
+{"w5o<CO  
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int responseCode=httpConnection.getResponseCode(); RWINdJZ  
if(responseCode>=400) 3d*wZ9qz  
{ 3\&I
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processErrorCode(responseCode); cg'z:_l  
return -2; //-2 represent access is error 7?"-NrW~  
} F)hUT@  
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String sHeader; ^ lM.lS>)  
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for(int i=1;;i++) &Vmx<w  
{ 2N}h<Yd9  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Ls(l  
//Utility.log(in.readLine()); )>8k8E  
sHeader=httpConnection.getHeaderFieldKey(i); ,kw:g&A  
if(sHeader!=null) C'xWRSDO  
{ tY6QhhuS:  
if(sHeader.equals("Content-Length")) 5u
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{ Cw]bhaG g  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ThJ`-Ro  
break; ^<QF*!  
} spv'r!*\ed  
} +]jJ:V  
else lehuJgz'OO  
break; $BWA=2$  
} 5!}fd/}Uk  
} ,S\AUUt%  
catch(IOException e){e.printStackTrace ();} PBp+(o-  
catch(Exception e){e.printStackTrace ();} _cD-E.E%  
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Utility.log(nFileLength); e[*%tx H  
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return nFileLength; <+)B8I^  
} DYaOlT(rE  
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//保存下载信息（文件指针位置） !t+eJj  
private void write_nPos() RL~]mI!U  
{ 6SN$El 0|G  
try{ :dj=kuUTbu  
output = new DataOutputStream(new FileOutputStream(tmpFile)); gtw?u b  
output.writeInt(nStartPos.length); gaxxB]8  
for(int i=0;i<nStartPos.length;i++) &<oDl_^  
{ #i0f}&
 
// output.writeLong(nPos); QsH?qI&2jp  
output.writeLong(fileSplitterFetch.nStartPos); Q!v]njCIB7  
output.writeLong(fileSplitterFetch.nEndPos); Kzf^ras4u  
} W"ldQ  
output.close(); $>!tpJw  
} g"Gj8QLDz  
catch(IOException e){e.printStackTrace ();} |aMeh;X t  
catch(Exception e){e.printStackTrace ();} `w/b];e1)  
} D.
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//读取保存的下载信息（文件指针位置） DS6g_SS3  
private void read_nPos() +n&9ZCH  
{ mUjM5ceAXO  
try{ o`}(1$a>  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Trt1M  
int nCount = input.readInt(); ,1|0]:  
nStartPos = new long[nCount]; 8/`ij?gn  
nEndPos = new long[nCount]; TOXZl3s5#  
for(int i=0;i<nStartPos.length;i++) fT  
{ &VfMv'%x  
nStartPos = input.readLong(); /dq(Z"O_  
nEndPos = input.readLong(); b 3i34,  
} e.?;mD  
input.close(); f~Q]"I8w  
} Xwt}WSdF`k  
catch(IOException e){e.printStackTrace ();} /E<:=DD<  
catch(Exception e){e.printStackTrace ();} _"c:Z!L  
} ".Sa[A;~  
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private void processErrorCode(int nErrorCode) hT?|:!ED.F  
{ i.G"21M  
System.err.println("Error Code : " + nErrorCode);  a5@XD_b  
} U((mOm6  
);oE^3]f  
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//停止文件下载 dtd}P~  
public void siteStop() 5;Q9Z1 `  
{ (|U|>@  
bStop = true; |tqYRWn0  
for(int i=0;i<nStartPos.length;i++) dPCn6  
fileSplitterFetch.splitterStop(); bbxo!K m"  
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} Ki(  
} l"app]uVZ  
//负责部分文件的抓取 SQJ }$#=  
**FileSplitterFetch.java k~HS_b*]d  
*/ z`KP }-  
package NetFox; 8bI;xjK^Q  
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import java.io.*; ?QG?F9?  
import java.net.*; d+Au`'{>  
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public class FileSplitterFetch extends Thread { :Wl`8p4]  
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;
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String sURL; //File URL `=JGlN7  
long nStartPos; //File Snippet Start Position 6UnWtLE  
long nEndPos; //File Snippet End Position O(CmdSk,  
int nThreadID; //Thread's ID Bl!R bh\  
boolean bDownOver = false; //Downing is over
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boolean bStop = false; //Stop identical >{@:p`*  
FileAccessI fileAccessI = null; //File Access interface {u{8QKeC  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException )9'Zb`n  
{ PWbi`qF)r  
this.sURL = sURL; N,~"8YSo  
this.nStartPos = nStart; %"g;K  
this.nEndPos = nEnd; 3?:?dy(3z  
nThreadID = id; z((9vi W  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 )h,
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} T f;:C]  
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public void run() +#MQ8d  
{ yi@mf$A|  
while(nStartPos < nEndPos && !bStop) Kb,#Ot  
{ (Q~(t  
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try{ Fooa~C"  
URL url = new URL(sURL); 'ghwc:Og|%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); y~/i{a;1y  
httpConnection.setRequestProperty("User-Agent","NetFox"); [y(AdZ0*  
String sProperty = "bytes="+nStartPos+"-"; X Cf!
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httpConnection.setRequestProperty("RANGE",sProperty); 0|D l/
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Utility.log(sProperty); !p$k<?WXc  
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InputStream input = httpConnection.getInputStream(); #,PB(  
//logResponseHead(httpConnection); 9i*Xd$ G  
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byte[] b = new byte[1024]; R'1L%srTM+  
int nRead; XX|wle1Kg  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 9_I#{?  
{ ![CF >:e  
nStartPos += fileAccessI.write(b,0,nRead); $mZpX:7/u8  
//if(nThreadID == 1) CY i{WV(:  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); bf&k:.v'8  
} Cv;\cI"&  
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Utility.log("Thread " + nThreadID + " is over!"); &7m)K>E27  
bDownOver = true; bk{.9nz2  
//nPos = fileAccessI.write (b,0,nRead); ;gmfWHB<  
} Y%A KN  
catch(Exception e){e.printStackTrace ();} g"o),$tm  
} ?2$0
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}  Im8c  
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//打印回应的头信息 U)y~{E~c34  
public void logResponseHead(HttpURLConnection con) [V_?`M  
{ JHIXTy__  
for(int i=1;;i++) kFsq23Ne  
{ U**v'%{s  
String header=con.getHeaderFieldKey(i); 4C[n@p2  
if(header!=null) hDc)\vzr  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); oYNp0Hc  
Utility.log(header+" : "+con.getHeaderField(header)); $dgez#TPL  
else .?CumaU  
break; ps=+wg?]  
} cAAyyc"yJ  
} wc6v:,&  
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public void splitterStop() 2W]y9)<c  
{ qtLXdSc  
bStop = true; vspub^;5\  
} 8 y+Nl&"V  
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} 2lm{:tS  
*2tG07kI  
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/* a{%]X(';  
**FileAccess.java !ii'hwFm$  
*//文件访问(定位，写) oHI/tS4 _  
package NetFox; ]psx\ZMa  
import java.io.*; e:H9!  
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6a\YD{D] _  
public class FileAccessI implements Serializable{ dxIt.h  
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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 WCPl}7>  
RandomAccessFile oSavedFile; aA/.EAc7  
long nPos; SXI3y  
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public FileAccessI() throws IOException F6h|AF|"  
{ ;r}>1LhN  
this("",0); 3x{2Dhi  
} FTfejk!  
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public FileAccessI(String sName,long nPos) throws IOException 2AZ)|dM'`  
{ G,J~Ed  
oSavedFile = new RandomAccessFile(sName,"rw"); zrJ/Fs+s  
this.nPos = nPos; |vY0[#E8&  
oSavedFile.seek(nPos); s*0PJ\E2  
} wWNHZv&  
|,wp@)e6h  
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public synchronized int write(byte[] b,int nStart,int nLen) /kY|PY  
{ @^';[P!  
int n = -1; fQB>0RR2  
try{ g@jAIy]  
oSavedFile.write(b,nStart,nLen); L9=D,C~  
n = nLen; 7>`VZ?  
} *4tJ|m6"Y6  
catch(IOException e) i@C$O.m(  
{ D/&^Y'|T  
e.printStackTrace (); iS"(  
} lV0\UySH  
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return n; u0(PWCi2
 
} e:~r_,K  
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} 2AAZZx +$  
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/* PmGW\E[ni  
**SiteInfoBean.java hF!t{ Lf3  
*/ !P&F6ViO=  
package NetFox; U 
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Z/wKUK;  
public class SiteInfoBean { `KgWaf-  
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private String sSiteURL; //Site's URL 65ctxxWv1  
private String sFilePath; //Saved File's Path 9aR-kcvJIJ  
private String sFileName; //Saved File's Name 9$z|kwU  
private int nSplitter; //Count of Splited Downloading File .#,!&Lt  
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public SiteInfoBean() =Kv*M
@  
{//nSplitter的缺省值为5 PSO9{!  
//default value of nSplitter is 5 >h0iq  
this("","","",5); pb(YA/  
} 3U<\s=1?X  
c7[<X<yk  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) L*Mt/  
{ gJ_{V;R  
sSiteURL= sURL; -Cjc~{B>7X  
sFilePath = sPath; 2Qqk?;^1  
sFileName = sName; }hralef #N  
this.nSplitter = nSpiltter; *Op;].>E  
fAu^eS%>7  
^ 2"r't  
} nVF?.c  
Dk!;s8}*c  
^T[8j/9o^  
public String getSSiteURL() eC^UL5>%
 
{ :Rh?#yO5  
return sSiteURL; p`jkyi  
} El;\#la  
BULf@8~(  
9+G.86Iky  
public void setSSiteURL(String value) I
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{ v`"z  
sSiteURL = value; &@O]'  
} [X'XxYbZ  
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public String getSFilePath() W=fw*ro  
{ .5ap9li]  
return sFilePath; DD3.el}6a  
} Fb&Xy{kt1  
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,GB~Cmc1<Q  
public void setSFilePath(String value) 8E:8iNbF  
{ wN"j:G(  
sFilePath = value; G x;U 3iV  
} !o+Y"* /  
g\CRx^s  
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public String getSFileName() i`3h\ku  
{ `ZCeuOH  
return sFileName; ^ lrq`1k  
} (!72Eaw:]  
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public void setSFileName(String value) B{UL(6\B  
{ sb Wn1 T U  
sFileName = value; %#xdD2oN  
} {sn RS)
-  

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public int getNSplitter() Zj@k3y  
{ Arg604V3  
return nSplitter; ~)\9f 1O{^  
} zn| S3c  
gnjh=anVX1  
b&AGVW
hh  
public void setNSplitter(int nCount) dWK; h  
{ J#h2~Hz!  
nSplitter = nCount; = GN1l[X  
} {E6M_qZ  
} xbbQ)sH&m  
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/* 4e6x1`Y{xB  
**Utility.java C-i9F%..  
*/ KxyD{W1  
package NetFox; oy8L{8?  
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public class Utility { x=1Iuc;&3  
[$PW {d8|  
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public Utility() Y?ADM(j  
{ G(g`>' m  
|mx)W}  
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}  -&N^S?  
<gvuCydsh  
//线程睡眠 -~ w5yd  
public static void sleep(int nSecond) 8+HXGqcv  
{ HPz9Er  
try{ &J>XKO nl  
Thread.sleep(nSecond); lD`@{A  
} O*
;$))<wX  
catch(Exception e) ZDMv8BP7  
{ B|\pzWD%  
e.printStackTrace (); )uj:k*`)  
} C[E[|s*l  
} 6j*L]Sc  
(u/-ud1p  
//日志 <ttrd%VW  
public static void log(String sMsg) 'CF?pxNQ l  
{ $<;!F=%8  
System.err.println(sMsg); (T290a9y>  
} <+7]EwVcn^  
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qDG{hvl[1r  
public static void log(int sMsg) Pu|PIdu!08  
{ (R'GrN>  
System.err.println(sMsg); mEL<d,XhI  
} .<#oLM^  
} yf > rG  
d-GU164  
,iUWLcOM  
/* ;rp("<g:>  
**TestMethod.java Z2Q'9C},m  
*/ Alo;kt@x  
package NetFox; w'[^RZW:j  
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ElFiR;  
public class TestMethod { *Sd}cDCO%  
3pzp6o2  
}MUQO<=*  
public TestMethod() 8iv0&91Z  
{ ///xx/weblogic60b2_win.exe &c?q#-^)\+  
try{ [-ONs
 
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); }s9eRmJs  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); V-1H(wRu  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 5|nT5oS  
fileFetch.start(); 4q9+a7@  
} 71S~*"O0f  
catch(Exception e){e.printStackTrace ();} <0EVq8h  
*5e"suS2  
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} cDkq@H:  
<\44%M"iC-  
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public static void main(String[] args) 3^jkd)xw  
{ [9<c;&$LU  
new TestMethod(); Q1Jw7R#?l  
} "b~-`ni  
} Gy]ZYo(  
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