http断点续传简单实现（java)

/* 9yz@hdG  
**SiteFileFetch.java %{-r'Yi%  
*/ uS5G(}[
 
package NetFox; 25 cJA4  
import java.io.*; (hEg
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import java.net.*; _y&XFdp  
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public class SiteFileFetch extends Thread { Y"L|D,ex  
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SiteInfoBean siteInfoBean = null; //文件信息Bean IhR
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long[] nStartPos; //开始位置 zf>*\pZE  
long[] nEndPos; //结束位置 ;;6$d{  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ~ #7@;C<nt  
long nFileLength; //文件长度 8@Bm2?$}g  
boolean bFirst = true; //是否第一次取文件 &(lQgi+^!  
boolean bStop = false; //停止标志 F^Bk @  
File tmpFile; //文件下载的临时信息 <HtGp6q  
DataOutputStream output; //输出到文件的输出流 =R
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） z'*"iaX<c  
public SiteFileFetch(SiteInfoBean bean) throws IOException W1521:  
{ $01csj  
siteInfoBean = bean; &u~Pp=kv  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); y)"rh/;  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); --EDr>'D5P  
if(tmpFile.exists ()) S+"Bq:u"  
{ TOhWfl;  
bFirst = false; mfG m>U  
read_nPos(); Gu@C*.jj!  
} E*h!{)z@F  
else N\];{pe>  
{ AOJ[/YpM  
nStartPos = new long[bean.getNSplitter()]; !C h1q  
nEndPos = new long[bean.getNSplitter()]; I{h KN V  
} 0' oXA'L-J  
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} s/.P/g%tA>  
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public void run() &>B"/z  
{ 8Ihl}aguW  
//获得文件长度 e"_kH_7sv  
//分割文件 JEaTDV_  
//实例FileSplitterFetch d14n
>  
//启动FileSplitterFetch线程 o2'Wu:Y"  
//等待子线程返回 8N+T=c  
try{ 0n'vF&E8  
if(bFirst) }%z%}V@(&  
{ ;>L8&m)R5  
nFileLength = getFileSize(); K8Q3~bMf  
if(nFileLength == -1) P@f#DX )  
{ k'k}/Hxub  
System.err.println("File Length is not known!"); C fM[<w   
} KyyVO"  
else if(nFileLength == -2) ([ -i5  
{ U1HG{u,"y  
System.err.println("File is not access!"); D6H?*4f]  
} +*Z'oCBJ,  
else h!v<J
  
{ ]Vmo>  
for(int i=0;i<nStartPos.length;i++) -cijLlz%+  
{ zhm0J-g  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); m[KmXPFht1  
} JXMH7  
for(int i=0;i<nEndPos.length-1;i++) lx=tOfj8  
{ 1;H"4u_IG&  
nEndPos = nStartPos[i+1]; *c [^/  
} T=)qD2?  
nEndPos[nEndPos.length-1] = nFileLength; !\[JWN@v  
} d,?Tq  
} d#]hqy  
:vX%0|  
#\`kg#&  
//启动子线程 ZX64kk+
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; )UM^#<-  
for(int i=0;i<nStartPos.length;i++) ]ly" K!1,  
{ GGhk~H4OP  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), i#hFpZ6u  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ~!!\#IX  
nStartPos,nEndPos,i); dJ m9''T')  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); A=5Ebu!z  
fileSplitterFetch.start(); R^$|D)(  
} ;Xy=;Z.]
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2,F9P+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); '5
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", as|w} $  
nEndPos = " + nFileLength); PCHspe9!y  
// fileSplitterFetch[nPos.length-1].start(); pA8As  
`:;q4zij;  
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//等待子线程结束 Y*PfU+y~  
//int count = 0; ~mARgv  
//是否结束while循环 AB`.K{h  
boolean breakWhile = false; >Rd~-w)!|  
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while(!bStop) : S3+
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{ 
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write_nPos(); 9i}$245lB  
Utility.sleep(500); y:}qoT_.  
breakWhile = true; z-
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for(int i=0;i<nStartPos.length;i++) |:&6eDlR  
{ 8"9&x} tl-  
if(!fileSplitterFetch.bDownOver) uT4|43< G  
{ w\YS5!P,V  
breakWhile = false; ,d,2Q  
break; Xs2 jR14`  
} w|-
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} ]5c(:T F  
if(breakWhile) "mf$E|  
break; jt on\9  
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//count++; +q'1P}e  
//if(count>4) 26rg-?;V^  
// siteStop(); kuy?n-1g  
} xF8n=Lc  
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System.err.println("文件下载结束！"); 1.F&gP)9  
} rBNVI;JZW  
catch(Exception e){e.printStackTrace ();} 8ROKfPj;z  
} p8_^6wfg  
]*\MIz{56'  
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//获得文件长度 &Y=0 0  
public long getFileSize() =+Fb\HvX{  
{  r!?ga  
int nFileLength = -1; (Z(S
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try{ > 0MP[  
URL url = new URL(siteInfoBean.getSSiteURL()); Z|uvrFa  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3TF_$bd{  
httpConnection.setRequestProperty("User-Agent","NetFox"); p>`rTaeZg  
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int responseCode=httpConnection.getResponseCode(); <.QaOLD  
if(responseCode>=400) 7;fC%Fq  
{ eZa*WI=  
processErrorCode(responseCode); fx5S2%f^  
return -2; //-2 represent access is error SQ_?4 s::  
} 8m?(* [[  
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String sHeader; lD
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for(int i=1;;i++) /{i~-DVME
 
{ dZ`Y>wH_  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 7H  
//Utility.log(in.readLine()); y9 {7+]  
sHeader=httpConnection.getHeaderFieldKey(i); %Hbq3U30  
if(sHeader!=null) 112WryS  
{ qjP~F  
if(sHeader.equals("Content-Length")) W^tD6H;  
{ WMf / S"=  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); cERIj0~  
break; m4hkV>$d  
} J[ Gpd  
} SKL4U5D{  
else @|a
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break; xz8e1M  
} ltNCti{Q  
} iWf+wC|  
catch(IOException e){e.printStackTrace ();} G&g;ROgY  
catch(Exception e){e.printStackTrace ();} 2!sPgIz  
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Utility.log(nFileLength); \34vE@V*  
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return nFileLength; 3U@jw,K!{A  
} ]<>cjk.ya  
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//保存下载信息（文件指针位置） SH?McBxS  
private void write_nPos() |u>(~6  
{ x.+T65X~4  
try{ X
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output = new DataOutputStream(new FileOutputStream(tmpFile)); \Ggh 95y  
output.writeInt(nStartPos.length); U6M~N0)Yr  
for(int i=0;i<nStartPos.length;i++) ; j!dbT~5  
{ bej(Ds0  
// output.writeLong(nPos); ]->"4,}  
output.writeLong(fileSplitterFetch.nStartPos); S;% &X  
output.writeLong(fileSplitterFetch.nEndPos); D;pI!S<#  
} <a6pjx>y  
output.close(); 6nW)2
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} PlkZ)S7C  
catch(IOException e){e.printStackTrace ();} 6<];}M_{  
catch(Exception e){e.printStackTrace ();} H -Mb:4  
} PAYw:/(P  
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//读取保存的下载信息（文件指针位置） V+E8{|dYL  
private void read_nPos() #DUfEZ  
{ {v|!];i  
try{ |UXSUP @s  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); +F8{4^w1  
int nCount = input.readInt(); z{rV|vQ  
nStartPos = new long[nCount];
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nEndPos = new long[nCount]; <1
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for(int i=0;i<nStartPos.length;i++) Tx;a2:6\[  
{ 7?Wte&C];p  
nStartPos = input.readLong(); ..)J6L5l  
nEndPos = input.readLong(); $l]:2!R  
} E!9WZY  
input.close(); k H.dtg_  
} A(FnU:  
catch(IOException e){e.printStackTrace ();} FCEy1^u  
catch(Exception e){e.printStackTrace ();} %~!4DXrMk  
} ^K?-+  
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private void processErrorCode(int nErrorCode) >WSh)(Cg  
{ PK[mf\G\  
System.err.println("Error Code : " + nErrorCode); h9)S&Sk{s  
} ybBmg'198  
|R}=HsYey  
>w S'z]T9  
//停止文件下载 k>($[;k|b  
public void siteStop() Ehx9-*]
 
{ Tv=lr6t8  
bStop = true; S^rf^%  
for(int i=0;i<nStartPos.length;i++) `8!9Fp  
fileSplitterFetch.splitterStop(); h=#w< @  
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} w2DC5ei'  
} ix!xLm9\  
//负责部分文件的抓取 m/=nz.  
**FileSplitterFetch.java A=N$5ZJ  
*/ 28!C#.(h  
package NetFox; b>uD-CSA  
*[[Gu^t^!  
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import java.io.*; s)1-xA{'.  
import java.net.*; =)Xj[NNRT
 
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public class FileSplitterFetch extends Thread { /|?$C7%a\D  
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String sURL; //File URL 2HeX( rB  
long nStartPos; //File Snippet Start Position &,&+p0CSI!  
long nEndPos; //File Snippet End Position hXTfmFy{n  
int nThreadID; //Thread's ID <z<>E1ZLI  
boolean bDownOver = false; //Downing is over M"
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boolean bStop = false; //Stop identical =[(34#  
FileAccessI fileAccessI = null; //File Access interface ,H]%4@]|o  
S/]\GG{  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ,X@o@W+L  
{  2v{WX  
this.sURL = sURL; FLi'}C  
this.nStartPos = nStart; &A0OYV3i.  
this.nEndPos = nEnd; CHgip&(.F  
nThreadID = id; U{2xgNJ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 #V>R#Oh}  
} P 9?cp{
*  
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public void run() !xsfhLZK  
{ Sm'Tz&!  
while(nStartPos < nEndPos && !bStop) CRb*sfKDL  
{ mnpk9x}m  
-#Zdf|  
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try{ V^_
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URL url = new URL(sURL); ]+D@E2E
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); rB[J*5v  
httpConnection.setRequestProperty("User-Agent","NetFox"); !Z$d<~Mq q  
String sProperty = "bytes="+nStartPos+"-"; JEto_&8,C  
httpConnection.setRequestProperty("RANGE",sProperty); N~)-\T:ap  
Utility.log(sProperty); ]oGd,v X  
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InputStream input = httpConnection.getInputStream(); "Rj PTRe:  
//logResponseHead(httpConnection); s=8H<'l  
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byte[] b = new byte[1024]; ]C \+b<  
int nRead; )?rq8VO  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) a4*v'Xc5  
{ Q"&Mr+  
nStartPos += fileAccessI.write(b,0,nRead); *'Yy@T8M  
//if(nThreadID == 1) R"t#dG]1t  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .QvD603%5  
} KFrsXf  
$)M3fZ$#  
)iN;1>  
Utility.log("Thread " + nThreadID + " is over!"); f}-'67*Y  
bDownOver = true; <i~xJi%1#  
//nPos = fileAccessI.write (b,0,nRead); !l[;,l  
} F[ E'R.:  
catch(Exception e){e.printStackTrace ();} '@{:FrG*U  
} io#}z4"'qY  
} MPB[~#:  
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| eBwcC#^  
//打印回应的头信息 `J.,dqGb  
public void logResponseHead(HttpURLConnection con) u^2`$W  
{ alb3oipOB  
for(int i=1;;i++) Y
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{ @O#!W]6NT6  
String header=con.getHeaderFieldKey(i); Cut~k"lv  
if(header!=null) VX)8pV$  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 65LtCQ}  
Utility.log(header+" : "+con.getHeaderField(header)); *;A ;)'  
else D \ rns+  
break; |1@O>GG  
} dseI~}  
} ZLQmEF[>  
!#0)`4O  
j<^!"_G]*?  
public void splitterStop() 5%,3)H{;t  
{ r^ r+
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bStop = true; Zl>SeTjB-  
} ^6W}ZLp  
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} H{}&|;0  
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/* B}"R@;N  
**FileAccess.java i%i~qTN  
*//文件访问(定位，写) MzvhE0ab  
package NetFox; #cY[c1cNv  
import java.io.*; LLx0X
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public class FileAccessI implements Serializable{ s$fM,l:!  
1Yb&E7j  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 NpVL;6?7T  
RandomAccessFile oSavedFile; ZKi&f,:  
long nPos; d@3
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public FileAccessI() throws IOException 0,hs%x>v  
{ U%vTmdOY  
this("",0); <'=!f6Wh  
} 971=OEyq*  
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public FileAccessI(String sName,long nPos) throws IOException n.+*_c8k  
{ @<W

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oSavedFile = new RandomAccessFile(sName,"rw"); Iy)1(upM  
this.nPos = nPos; ,M.C]6YMr  
oSavedFile.seek(nPos); ~ 5}t;  
} pm O9mWq   
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public synchronized int write(byte[] b,int nStart,int nLen)
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{ 'o&d!  
int n = -1; 6J;!p/C8E  
try{ D`XXR}8V  
oSavedFile.write(b,nStart,nLen); ;@;aeu  
n = nLen; 6mcb'hy  
} _9BL7W $;  
catch(IOException e) czRBuo+k+  
{ 9B~&d(Bm  
e.printStackTrace (); \S h/<z  
} Tg)F.):  
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return n; -VohU-6 |  
} YdD; Qx#O  
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}
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 kF1$  
/* SS/vw%  
**SiteInfoBean.java I[E 6N2  
*/ b`e_}
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package NetFox; Ug*B[q/  
 ~&~4{  
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public class SiteInfoBean { hNc8uV{r=  
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private String sSiteURL; //Site's URL ,!> ~izB  
private String sFilePath; //Saved File's Path 4Uny.C]  
private String sFileName; //Saved File's Name Yo%U{/e  
private int nSplitter; //Count of Splited Downloading File t'K+)OK  
;"D}"nL  
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public SiteInfoBean() +
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{//nSplitter的缺省值为5 +  }"+  
//default value of nSplitter is 5 2*snMA  
this("","","",5); mc]+j,d  
} H:~bWd'iz  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) >FE8CH!W&  
{ ")8l'^Mq2  
sSiteURL= sURL; IYn`&jS{  
sFilePath = sPath; )B]"""J  
sFileName = sName; wXQu%F3  
this.nSplitter = nSpiltter; ~2*LWH*@  
r (m3"Xu6O  
3?E7\\/R  
} B2r[oT R  
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public String getSSiteURL() #GGa,@O  
{ xn, u$@F  
return sSiteURL; <?A4/18K  
} X!h>13fW  
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{ {?-& yA  
public void setSSiteURL(String value) w!UF^~  
{ KY&Lv^1_|  
sSiteURL = value; |}{gE=]  
} `N[@lV\xp!  
=.s0"[%   
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public String getSFilePath() cPcH 8Vd  
{ i>S@C@~  
return sFilePath; *Y85evq  
} W(s5mX,Kv  
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public void setSFilePath(String value) &Sb)a  
{ zgFL/a<  
sFilePath = value; i).Vu}W
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} x((u  
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public String getSFileName() wHbmK  
{ `Fcr`[  
return sFileName;
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} T=/c0#Q|q  
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public void setSFileName(String value) N!.o`4 "z  
{ 1E$\&*(  
sFileName = value; vcW(?4e  
} In4VS:dD  
7zzFM  
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public int getNSplitter() 'g<"@SS+  
{ N?c~AEk9U  
return nSplitter; <f (z\pi1  
} 2aTq?ZR|8A  
NEIF1(:  
)z&C&Gqz  
public void setNSplitter(int nCount) ~;6^n  
{ *_YH}U  
nSplitter = nCount; AxEdQRGk  
} oM1C/=8   
} F&`%L#s|  
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/* t[;-gi,,  
**Utility.java 5OPvy,e6  
*/ G5|nt#>  
package NetFox; v~x`a0  
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public class Utility { PE;<0Cz\  
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public Utility() kXdXyq  
{ ,f%
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}@.@k6`n  
(mbm',%-(  
} Dy5&-yk  
CqWO 0  
//线程睡眠 `_.:O,^n^  
public static void sleep(int nSecond) y%9Hu
  
{ .5>]DZn6  
try{ )" Z|x  
Thread.sleep(nSecond); ^7Z?}tgU  
} 1Z?uT[kR  
catch(Exception e) oNYFbZw  
{ Vo[.^0  
e.printStackTrace (); cSv;HN:  
} E3{kH 7_'\  
} H/*sl
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//日志 @/N]_2@8;  
public static void log(String sMsg) 1
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{ mz x$
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System.err.println(sMsg); #lik: ?  
} :RDk{^b)  
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bz 7?F!  
public static void log(int sMsg) OZz/ip-!lc  
{ Zcw<USF8  
System.err.println(sMsg); fHwS12SB  
} OK-*TPrc  
} T+gH38!e  
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yzl}!& E  
/* )b%zYD9p  
**TestMethod.java 'xG{q+jj'  
*/ [j
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package NetFox; W@zxGH$z>  
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public class TestMethod { JoG(Nk
]  
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public TestMethod() N_FjEZpX  
{ ///xx/weblogic60b2_win.exe ,*\s  
try{ UHk)!P>  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); x1Z'_Qw  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); RZVZ#q(DU  
SiteFileFetch fileFetch = new SiteFileFetch(bean); t+pA9^$[`  
fileFetch.start(); j%ZBAk)}  
} "1>w\21  
catch(Exception e){e.printStackTrace ();} T
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} CRiqY_gBf  
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* RX^ z6  
public static void main(String[] args) \J#&]o)Y  
{ <gFisc/#r  
new TestMethod(); "~zLG"  
} F|'u0JQ)$  
} {KK/mAp{  
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