http断点续传简单实现（java)

/* M(1cf(<+  
**SiteFileFetch.java :_|Xr'n`A  
*/ ojyP.R  
package NetFox; d&lT/S  
import java.io.*; S$=caZ?  
import java.net.*; J1w,;T\55  
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public class SiteFileFetch extends Thread { Ept=&mJPu  
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SiteInfoBean siteInfoBean = null; //文件信息Bean :F_>`{  
long[] nStartPos; //开始位置 '~VF
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long[] nEndPos; //结束位置 rZ&li/Z
 
FileSplitterFetch[] fileSplitterFetch; //子线程对象 WRrg5&._q  
long nFileLength; //文件长度 hC4 M}(XM  
boolean bFirst = true; //是否第一次取文件 nRyx2\Py+  
boolean bStop = false; //停止标志 yeam-8  
File tmpFile; //文件下载的临时信息 ,Jx.Kj.,  
DataOutputStream output; //输出到文件的输出流 Pk;1q?tGw  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ^{YK'60  
public SiteFileFetch(SiteInfoBean bean) throws IOException 1vYa&!  
{ N cp   
siteInfoBean = bean; Yx&d\/9  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); a ?\:,5=  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); H43d[@h  
if(tmpFile.exists ()) Z<*"sFpAO  
{ /9,y+"0SQz  
bFirst = false; gnYo/q
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read_nPos(); MEu{'[C  
} ~iPXn1  
else T7|=`~  
{ E#Ol{
6  
nStartPos = new long[bean.getNSplitter()]; Y$#6%`*#>n  
nEndPos = new long[bean.getNSplitter()]; p,tkVedR  
} \E'z+0  
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} yMD3h$w3a  
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public void run() ;U3K@_  
{ 1p$*N  
//获得文件长度 /l+"aKW 2  
//分割文件 :2V|(:^'  
//实例FileSplitterFetch 1,7 }ah_  
//启动FileSplitterFetch线程 <rvM)EJv|  
//等待子线程返回 I%b5a`7  
try{ MdFFt:y:  
if(bFirst) b`JS&E  
{ v4K! BW  
nFileLength = getFileSize(); WM%w_,Z  
if(nFileLength == -1) Dk&(QajL  
{ ~
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System.err.println("File Length is not known!"); h/2@4XKj  
} eFotV.T!#  
else if(nFileLength == -2) F&lH5  
{ @NL37C  
System.err.println("File is not access!"); 1!yd(p=cL  
} xLms|jS  
else Xpv<v[a  
{ -zWNQp$  
for(int i=0;i<nStartPos.length;i++) $$SJLV
  
{ J*_^~t  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 4l>U13~#  
} Z|fi$2k0!  
for(int i=0;i<nEndPos.length-1;i++) 4TyzD%pOw  
{ {?q`9[Z  
nEndPos = nStartPos[i+1]; ^/cqE[V~,  
} .V\~#Ro$G  
nEndPos[nEndPos.length-1] = nFileLength; hi4-Z=pl  
} &M tF  
} [mj=m
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//启动子线程 DliDBArxZ  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; WYP\J1sy  
for(int i=0;i<nStartPos.length;i++) s>1\bio*I  
{ `GlOl-  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !? H:?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), !1K.HdK  
nStartPos,nEndPos,i); 5j\Kej  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos);  E(wS6  
fileSplitterFetch.start();
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} LK!sk5/  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Efoy]6P\  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); TU;AO%5  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", _yF@k~ h  
nEndPos = " + nFileLength); 9I`0`o"A  
// fileSplitterFetch[nPos.length-1].start(); `gF`Sgz  
<f=<r*6  
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//等待子线程结束 hsJ^Au=})w  
//int count = 0; rP,|  
//是否结束while循环 [P0c,97_ H  
boolean breakWhile = false; 0l/7JH_@V  
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while(!bStop) -0BxZ AW=  
{ wWSw0 H/  
write_nPos(); a8v\H8@X  
Utility.sleep(500); xA<-'8ST  
breakWhile = true; kM@e_YtpY  
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for(int i=0;i<nStartPos.length;i++) \}%_FnP0ZU  
{ I2pE}6q  
if(!fileSplitterFetch.bDownOver) >o%X;U 3  
{ vbX.0f "n  
breakWhile = false; p!)PbSw#  
break; P)XR9&o':  
} S4c-i2Rq  
} :4x6dYNU  
if(breakWhile) u\/TR#b  
break; L@jpid95  

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ZoYllk   
//count++; w~+\Mfz  
//if(count>4) MmU`i ,z  
// siteStop(); WnU2.:  
} ,Z :2ba  
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System.err.println("文件下载结束！"); MiKq|  
} M= |is*t  
catch(Exception e){e.printStackTrace ();} ]Nw]po+  
} m5a'Vs  
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>|gXE>  
//获得文件长度 O2yD{i#l*#  
public long getFileSize() IP-M)_I
  
{ NPFI^Uj#A  
int nFileLength = -1; U3-MvI,Q  
try{ 9i lJ  
URL url = new URL(siteInfoBean.getSSiteURL()); N})vrB;1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); I 9?X  
httpConnection.setRequestProperty("User-Agent","NetFox"); $ %|b6Gr/&  
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int responseCode=httpConnection.getResponseCode(); ~IPATG  
if(responseCode>=400) {X<_Y<  
{ ;Jb%2?+=!  
processErrorCode(responseCode); MtgY `p  
return -2; //-2 represent access is error 2P${5WT  
} .wTb/x  
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String sHeader; :oYSvK7>  
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for(int i=1;;i++) s jaaZx1  
{ <lU(9) L;&  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); R#?atL$(  
//Utility.log(in.readLine()); LaZ @4/z!  
sHeader=httpConnection.getHeaderFieldKey(i); DHyQ:0q  
if(sHeader!=null) T-lP
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{ ;9-J=@KY4  
if(sHeader.equals("Content-Length")) BZKg:;9  
{ jq_4x[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); jeO`45O  
break; n=0^8QQ  
} u-bgk(u  
} ,J<+Wxz  
else w@YPG{"j  
break; 3h%Nd&_9  
} /QCg E~  
} YguW2R=6]  
catch(IOException e){e.printStackTrace ();} FP
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catch(Exception e){e.printStackTrace ();} cRCji^,KJ  
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Utility.log(nFileLength); D vN0h(?  
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return nFileLength; _5p]Arg?}&  
} _5b~3K/V  
$]W*;MTI}  
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//保存下载信息（文件指针位置） J-G)mvkv  
private void write_nPos() cg_tJ^vrY  
{ Qw_> l}k/  
try{ ;NAKU  
output = new DataOutputStream(new FileOutputStream(tmpFile));
o/vD]Fs  
output.writeInt(nStartPos.length); P]2 /}\f  
for(int i=0;i<nStartPos.length;i++) aW;)-0+  
{ )(1tDQ`L>  
// output.writeLong(nPos); n$>_2v  
output.writeLong(fileSplitterFetch.nStartPos); "]=XB0)  
output.writeLong(fileSplitterFetch.nEndPos); R!\._m?\h  
} kFT*So`'  
output.close(); zxd<C
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} unnuSW#v=  
catch(IOException e){e.printStackTrace ();} vDR> Q&/K  
catch(Exception e){e.printStackTrace ();} p]toDy-}  
} B{S^t\T$  
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//读取保存的下载信息（文件指针位置） %x}Unk  
private void read_nPos() jH;L7
 
{ 8u"C7} N_  
try{ x #|t#N%  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 5g'aNkF6>  
int nCount = input.readInt();  (tT%rj!  
nStartPos = new long[nCount]; w*(1qUF#%  
nEndPos = new long[nCount]; ,w
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for(int i=0;i<nStartPos.length;i++) Ly1t'{"7  
{ bI
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nStartPos = input.readLong(); M?n}{0E4  
nEndPos = input.readLong(); mM+^v[=  
} .\)e

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input.close(); S3QX{5t\  
} B
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catch(IOException e){e.printStackTrace ();} {n<1uh9~$8  
catch(Exception e){e.printStackTrace ();} UD5
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} |h((SreO  
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private void processErrorCode(int nErrorCode) a+9
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{ \!0~$?_)P  
System.err.println("Error Code : " + nErrorCode); wLg@BSC.  
} Y]B9*^d<  
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u=#_8e(9Z  
//停止文件下载 Cs,t:aj
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public void siteStop() z}*L*Sk  
{ mhs%8OTN  
bStop = true; u2U+uD@yA  
for(int i=0;i<nStartPos.length;i++) wNh\pWA  
fileSplitterFetch.splitterStop(); ? fM_Y  
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} x51xY$
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} H4M`^r@)'  
//负责部分文件的抓取 <#T#+uO  
**FileSplitterFetch.java #,!/Cnqis  
*/ !P
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package NetFox; u1Wixjd|  
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import java.io.*; gA2]kZg  
import java.net.*; )Oj{x0{\Q  
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public class FileSplitterFetch extends Thread { &iJvkt  
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String sURL; //File URL }
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long nStartPos; //File Snippet Start Position 0F&(}`V  
long nEndPos; //File Snippet End Position `2HNQiK'@  
int nThreadID; //Thread's ID <*ME&cgh4  
boolean bDownOver = false; //Downing is over DM(c :+K-  
boolean bStop = false; //Stop identical ^X:g C9  
FileAccessI fileAccessI = null; //File Access interface sHSg _/|  
bHzH0v]:  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException -e*(+  
{ - KaU@t  
this.sURL = sURL; cA!o xti  
this.nStartPos = nStart; ovvg"/>L  
this.nEndPos = nEnd; 7X.B  
nThreadID = id; V?jot<|$  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 o&?:pE  
} l<s6Uu"  
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public void run() ( D
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{ Qf}}/k|)k  
while(nStartPos < nEndPos && !bStop) TM,Fab &  
{ g6.Tx]?b$  
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try{ FyllVrK  
URL url = new URL(sURL); }eLth0d`'o  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 73+)> "x>  
httpConnection.setRequestProperty("User-Agent","NetFox"); r}#,@<  
String sProperty = "bytes="+nStartPos+"-"; $~1~+s0$  
httpConnection.setRequestProperty("RANGE",sProperty); e:n3@T,
R  
Utility.log(sProperty); U%tpNWB  
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InputStream input = httpConnection.getInputStream(); cN]g^  
//logResponseHead(httpConnection); kfkcaj4l]  
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{6;S= 9E\
 
byte[] b = new byte[1024]; oJ0ZZu?{D  
int nRead; mX@!O[f%9e  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) bN>|4hS  
{ hoZM;wC  
nStartPos += fileAccessI.write(b,0,nRead); 5?Rzyfwk|  
//if(nThreadID == 1) V<t!gT#&o!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); SD1M`PI  
} jg(cpo d  
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Utility.log("Thread " + nThreadID + " is over!"); 1u_< 1X3  
bDownOver = true; "pQ)5/e  
//nPos = fileAccessI.write (b,0,nRead); F{ sPQf'  
} dpB\=  
catch(Exception e){e.printStackTrace ();} `& ]H`KNa  
} OUtMel_
 
} ~s) `y2Y  
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//打印回应的头信息 <io;d$=}  
public void logResponseHead(HttpURLConnection con) e]3b0`E  
{ c+G%o8  
for(int i=1;;i++) sN@=Ri?\  
{ ko`KAU<T_  
String header=con.getHeaderFieldKey(i); SfGl*2  
if(header!=null) ?w>-ya  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); /jd.<r=_I  
Utility.log(header+" : "+con.getHeaderField(header)); 4cJka~  
else 'a=QCO 0  
break; e!1am%aE  
} !sh>`AF  
} ,h* 'Cs04h  
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public void splitterStop() G"F:68  
{ N/r8joi#  
bStop = true; aQL$?,  
} ^7V{nT@H3  
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} 5>S)+p  
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/* JnXVI!+JDL  
**FileAccess.java "Rr650w[  
*//文件访问(定位，写) 'EkuCL  
package NetFox; >1NE6T  
import java.io.*; 1p COLC%1  
}\hz@G<  
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public class FileAccessI implements Serializable{ A%%Vyz  
ZRj&k9D^U  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Pfl8x  
RandomAccessFile oSavedFile; ,g{Ob{qT  
long nPos; 75*q^ui  
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public FileAccessI() throws IOException 0z`-fQfK  
{ ^(T_rEp  
this("",0); ;;7:l,vy  
} d\j[O9W>  
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public FileAccessI(String sName,long nPos) throws IOException 6"u"B-cz  
{ ,?`Zrxe[  
oSavedFile = new RandomAccessFile(sName,"rw"); 3s$vaV~(a  
this.nPos = nPos; 9<-7AN}Z  
oSavedFile.seek(nPos); L3'$"L.|u  
} +`'>  
3 cF4xUIZ  
!A&>Eeai  
public synchronized int write(byte[] b,int nStart,int nLen) T6I$7F  
{ raB',Vp  
int n = -1; +`l)W`zX  
try{ V D.T=(  
oSavedFile.write(b,nStart,nLen); aW;DfH  
n = nLen; N2$uw@s  
} %O\zYtQR  
catch(IOException e) \??20iz  
{ ^/DP%^D  
e.printStackTrace (); $Lt'xW`8  
} p{oc}dWin  
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return n; u/(~ewI  
} &^(4yw(~  
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} ?[c{pb,|  
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/* 7L$\S[E  
**SiteInfoBean.java \,-e>  
*/ v&8
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package NetFox; n+SHkrW  
 -wQ@z6R  
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public class SiteInfoBean { ANq3r(  
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private String sSiteURL; //Site's URL 9|qzFmE#  
private String sFilePath; //Saved File's Path rIQ%X`Y  
private String sFileName; //Saved File's Name *dPG[ }  
private int nSplitter; //Count of Splited Downloading File QHgkfo  
(e_l1O?  
^!*nhs%  
public SiteInfoBean() 8\Kpc;zb  
{//nSplitter的缺省值为5 n'qWS/0U=  
//default value of nSplitter is 5 BKk+<#Ti  
this("","","",5); vX<^x2~9(  
} G?<uw RV  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) aXh~w<5F  
{ )8*}-z  
sSiteURL= sURL; \"1%>O*  
sFilePath = sPath; @cu#rWiG  
sFileName = sName; \/F*JPhy  
this.nSplitter = nSpiltter; XWag+K  
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} #&K?N  
Ox9M![fC  
U
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public String getSSiteURL() e3,@prr  
{ n<
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return sSiteURL; mKuY=#RP  
} <ZjT4><  
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@Io@1[kj  
public void setSSiteURL(String value) '9@AhiNV  
{ /Csk"IfuO  
sSiteURL = value; S9%ZeM+  
} @K1'Q!S*  
/B)`pF.n  
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public String getSFilePath() ToM1#]4  
{ g9@H4y6fe=  
return sFilePath; pch8A0JAl)  
} <kKuis6h  
pMd!Jl#(N  
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public void setSFilePath(String value)
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{ }h1y^fuGi  
sFilePath = value; -8
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} C2H2*"  
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@]7s`?  
public String getSFileName() $g_|U:,  
{ %\T#Ik~3  
return sFileName; m\G
45%m  
} *R3^:Y&  
1|:'jK#gE  
/<1zzeHRSD  
public void setSFileName(String value) +h@ZnFp3  
{ oc;4;A-;`c  
sFileName = value; DdqE6qE  
} lQ&J2H<
w  
&Gs/#2XQ  
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public int getNSplitter() !GnwE  
{ g[N3jt@  
return nSplitter; TjicltQi4  
} X}g"_wN,g>  
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public void setNSplitter(int nCount) j937tn!Q  
{ .f&Z+MQ
 
nSplitter = nCount; Hi nJ}MF  
} T&'LQZM8  
} CbFO9q  
jHk.]4&0  
sKC(xO@L;`  
/* i,,mt_/,  
**Utility.java P"+R:O\!g  
*/ XZT|ID_u"  
package NetFox; O Ke 9/._  
JqV}$E"M2  
<[vsGUbc  
public class Utility { f`YHZ O  
49= K]
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public Utility() EQ]>^VE2B  
{ j\iNag(  
ySHpN>U  

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} Y>x3`f]  
a]!u go}  
//线程睡眠 JA% y{Wb  
public static void sleep(int nSecond) 08/Tk+  
{ B.L_EIw  
try{ poy_?7G  
Thread.sleep(nSecond); ZEs^b  
} m -0}Pe9L  
catch(Exception e) mQ3gp&d3W  
{ 5w5"rcV  
e.printStackTrace (); 0E9 lv"3o  
} ,/Q`gRBh"  
} hqa6aYY x  
<5zr|BTF]F  
//日志 Zt}b}Bz  
public static void log(String sMsg) -$I$zo  
{ EAHdt=8W{  
System.err.println(sMsg); OZ/"W)  
} H(kxRPH4@]  
=.l>Uw!  
mR~S$6cc  
public static void log(int sMsg) JFq<sY!  
{ >7z(?nQYT^  
System.err.println(sMsg); *ZIX76y<!A  
} iD/+#UTY  
} |h6,.#n  
vhzz(UPUt  

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/* Q.Y6  
**TestMethod.java w$j6!z  
*/ _&[-< cu  
package NetFox; !Ej?9LHo  
[LrO"9q(  
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public class TestMethod { VVfTFi<  
y5XFJj  
^4xl4nbx  
public TestMethod() U+aiH U9  
{ ///xx/weblogic60b2_win.exe &{q<  
try{ t"OP*  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); _+Z5qUmQ  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); !wC( ]Y  
SiteFileFetch fileFetch = new SiteFileFetch(bean); /T2 v`Li  
fileFetch.start(); ExF6y#Y G<  
} >8&fFq  
catch(Exception e){e.printStackTrace ();} N*\ri0  
l;@bs  
kx;7/fH  
} Q_dMuoI  
HkY#i;%N  
i-.AD4  
public static void main(String[] args) 2b Fr8FUt-  
{ VxE;t
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new TestMethod(); [fY7|  
} k1SD{BL  
} ?)Je%H  
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