http断点续传简单实现（java)

/* St|sUtj<r  
**SiteFileFetch.java $f1L<euH  
*/ 1}S_CR4XBs  
package NetFox; _<;#=l  
import java.io.*; ksDG8^9>]  
import java.net.*; \'E_  
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":]O3 D{r  
public class SiteFileFetch extends Thread { `<HY$PAe  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 54uTu2  
long[] nStartPos; //开始位置 b${Kj3(  
long[] nEndPos; //结束位置 ys+?+dY2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 6ap,XFRMh  
long nFileLength; //文件长度 <@*mFq0,  
boolean bFirst = true; //是否第一次取文件 xR#hU;E}  
boolean bStop = false; //停止标志 /6gRoQ%j  
File tmpFile; //文件下载的临时信息 P]y2W#Rs  
DataOutputStream output; //输出到文件的输出流 qh.c#t  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） iZSjT"l^  
public SiteFileFetch(SiteInfoBean bean) throws IOException B]*&lRR  
{ +bRL.xY  
siteInfoBean = bean; 7/*;rT  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ew`R=<mZ,7  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); B.Xm*adBT  
if(tmpFile.exists ()) Ccc6 ko_  
{ HNh=ig
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bFirst = false; jC\R8_  
read_nPos(); i"e)LJz  
} ZgXh[UHQy  
else %mcuYR'D}  
{ e#zGLxa  
nStartPos = new long[bean.getNSplitter()]; Fa/i./V2  
nEndPos = new long[bean.getNSplitter()]; p:4vjh=1h  
} jG.*tuf  
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} Q?Nzt;)!.  
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public void run() 2l!"OiB.P  
{ C*
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//获得文件长度 hCo&SRC/5  
//分割文件 g{D&|qWj  
//实例FileSplitterFetch V)a6H^l  
//启动FileSplitterFetch线程 /kJ*WA?J  
//等待子线程返回 C#r`oZS1  
try{ #qn)Nq(  
if(bFirst) qq?>ulu*W  
{ tlcA\+%)  
nFileLength = getFileSize(); 92VAQU6  
if(nFileLength == -1) L,D!T&B  
{ )5&m:R9  
System.err.println("File Length is not known!"); pDKJLa  
} J-QQ!qa0  
else if(nFileLength == -2) e6_.ID'3  
{ q?MYX=Y6  
System.err.println("File is not access!"); >WD^)W fa  
} I{Kc{MXn  
else z)]EB6uRg  
{ TY#1Z )%  
for(int i=0;i<nStartPos.length;i++) i5wA=K_  
{ tL
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); '|q:h  
} Sm1bDa\!=  
for(int i=0;i<nEndPos.length-1;i++) Dr2h-  
{ JA)gM  
nEndPos = nStartPos[i+1]; [n}c}%  
} lZua"Ju  
nEndPos[nEndPos.length-1] = nFileLength; c]"B)I1L  
} xUw\Y(!  
} -w2ga1  
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M84LbgGM%  
//启动子线程 2h:f6=)r/u  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 05zHLj  
for(int i=0;i<nStartPos.length;i++) ~XxD[T5  
{ C=m Y  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), D-~Jj&7  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), b:3hKW  
nStartPos,nEndPos,i); y,
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); U'lD|R,g  
fileSplitterFetch.start(); p/5!a~1'xN  
} q-o>yjT~  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), lt$797  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); h1kPsgzR  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", A,og9<+j-  
nEndPos = " + nFileLength); ljis3{kn""  
// fileSplitterFetch[nPos.length-1].start(); _F*w ,b$8  
,G:4H%?  
Pz)QOrrG~  
//等待子线程结束 M$?6 '  
//int count = 0; 5ya3mNE  
//是否结束while循环 IMR|a*=`c  
boolean breakWhile = false; ~^euaOFU 6  
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while(!bStop) v\k,,sI  
{ }ri*e2y)  
write_nPos(); ]EcZ|c7o9y  
Utility.sleep(500); 0>;#vEF*1  
breakWhile = true; {x4[Bx1  
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for(int i=0;i<nStartPos.length;i++) 9j2I6lGQ  
{ |)4$\<d  
if(!fileSplitterFetch.bDownOver) u7C{
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{ 2%qn!+.  
breakWhile = false; ]dK]a:S  
break; rO`g~>-  
} 
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} ]~.J@ 1?  
if(breakWhile) ZYt
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break; <D dHP  
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7, 13g)  
//count++; 9HE(*S  
//if(count>4) G}-.
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// siteStop(); 4d 3Znpf  
} +7Lco"\w<  
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System.err.println("文件下载结束！"); `eWcp^|  
} ._&lG3'  
catch(Exception e){e.printStackTrace ();} N.G*ii\  
} sB
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:]^P^khK  
//获得文件长度 a!:8`X~[/$  
public long getFileSize() WDGGT.hG  
{ zn ?;>Bl  
int nFileLength = -1; ^!<7#kX  
try{ !~N4}!X3du  
URL url = new URL(siteInfoBean.getSSiteURL()); N &[,nUd  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ]k:m2$le  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8T)zB6ng  
&7T H V  
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int responseCode=httpConnection.getResponseCode(); CdDd+h8  
if(responseCode>=400) '^l^g
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{ i f<<lq  
processErrorCode(responseCode); ]X~g@O{>_  
return -2; //-2 represent access is error `,Nn4  
} M#cr*%  
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String sHeader; >NRz*h#  
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for(int i=1;;i++) ,imvA5  
{ n+qVT4o  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); &fSc{/  
//Utility.log(in.readLine()); EO&ACG  
sHeader=httpConnection.getHeaderFieldKey(i); tt]V$V  
if(sHeader!=null) 0['"m^l0S  
{ = (gmd>N  
if(sHeader.equals("Content-Length")) eAsX?iaH  
{ (Q5@MfK`  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); paNw5] -  
break; egvy#2b@  
} &@HNz6KO  
} ix9HSa{d  
else
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break; mp,e9Nd;  
} N+M&d3H`  
} f4k5R  
catch(IOException e){e.printStackTrace ();} ;(Xe@OtW  
catch(Exception e){e.printStackTrace ();} `MsYgd  
>I& jurU#  
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Utility.log(nFileLength); NVJ&C]H6  
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return nFileLength; {?/8jCVd  
} 48CI8[T  
7p.h{F'A  
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//保存下载信息（文件指针位置） U>_IYT  
private void write_nPos() 9*|3E"Vr  
{ %md^S |  
try{ V 7l{hEo3?  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ?JgO-.  
output.writeInt(nStartPos.length); H_?B{We  
for(int i=0;i<nStartPos.length;i++) d{yIy'+0/  
{ pf8O`e,Awf  
// output.writeLong(nPos); :5S |x/  
output.writeLong(fileSplitterFetch.nStartPos); x$n~f:1Y  
output.writeLong(fileSplitterFetch.nEndPos); 7<:Wq=e!r  
} 3_MS'&M  
output.close(); AzW7tp;t=  
} qEJ8o.D-=  
catch(IOException e){e.printStackTrace ();} u\XkXS`  
catch(Exception e){e.printStackTrace ();} )@,90Vhh  
} 3kiE3*H  
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//读取保存的下载信息（文件指针位置） qB F!b0lr  
private void read_nPos() R6!cK[e]4  
{ {jhm
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try{ 2{e dW+  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 7-d}pgVK  
int nCount = input.readInt(); {OO*iZ.O  
nStartPos = new long[nCount]; ov`^o25f  
nEndPos = new long[nCount]; ?+n&hHRg  
for(int i=0;i<nStartPos.length;i++) JOrELrMx
 
{ N^\2 _T  
nStartPos = input.readLong(); u m:0y,  
nEndPos = input.readLong(); f6B-~x<l  
} dK}WM46$  
input.close(); #0bO)m+NZ  
} oWp}O?  
catch(IOException e){e.printStackTrace ();} ZU|6jI}  
catch(Exception e){e.printStackTrace ();} .?rbny  
} _ }E-~I>  
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private void processErrorCode(int nErrorCode) rGnI(m.  
{ |rHG%VnBH  
System.err.println("Error Code : " + nErrorCode); u>}w-  
} U g}8y8  
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P+dA~2k  
//停止文件下载 9- xlvU,
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public void siteStop() mRhd/|g*  
{ 7fju  
bStop = true; <0u\dU  
for(int i=0;i<nStartPos.length;i++) vi]
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fileSplitterFetch.splitterStop(); &8<<!#ob  
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} GilQtd3\  
} A~Z6jK  
//负责部分文件的抓取 v7i^O`{eD?  
**FileSplitterFetch.java d,c8Hs8  
*/ J~Cc9"(  
package NetFox; E/mubA(&  
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import java.io.*;  hv+|s(  
import java.net.*; 3 p
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public class FileSplitterFetch extends Thread { }p~OCW!  
6'xomRpYN  
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String sURL; //File URL GE1i+.+-.  
long nStartPos; //File Snippet Start Position /g_9m  
long nEndPos; //File Snippet End Position -S"5{N73  
int nThreadID; //Thread's ID X E|B)Q(  
boolean bDownOver = false; //Downing is over ZgV~W#t  
boolean bStop = false; //Stop identical &v^!y=Bt  
FileAccessI fileAccessI = null; //File Access interface U|gpCy  
{<qF}i:V  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException '_:(oAi,C  
{ B*\$ /bk,  
this.sURL = sURL; !FTNmyM~F  
this.nStartPos = nStart; w8O" =},  
this.nEndPos = nEnd; IY=/`g  
nThreadID = id; jY7=mAd  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 *YWk1Cwjo  
} 00ofHZ  
?4XnEDAm  
%.mEBI=hs  
public void run() qgoJ4Z*  
{ hd+]Ok7"  
while(nStartPos < nEndPos && !bStop) 9\HR60V  
{ sI_7U^"[  
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try{ |]`hXr  
URL url = new URL(sURL); \(I0wEQo$  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); @q K]JK  
httpConnection.setRequestProperty("User-Agent","NetFox"); U{6oLqwq3Y  
String sProperty = "bytes="+nStartPos+"-"; `@[l\.Vt:  
httpConnection.setRequestProperty("RANGE",sProperty); ]r4bRK[1  
Utility.log(sProperty); i AdGgK  
X) V7bVW  
[4sEVu}  
InputStream input = httpConnection.getInputStream(); HPrq1QpK  
//logResponseHead(httpConnection); q:I$EpKf?Q  
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8S\RN&T$  
byte[] b = new byte[1024]; u*3NS$vH  
int nRead; UtnZNdlv  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 07V8;A<,  
{ ,7W:fwdR  
nStartPos += fileAccessI.write(b,0,nRead); {( #zcK  
//if(nThreadID == 1) o*">KqU`b  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 62)d22  
} NzQ9Z1Mxy  
: [q0S@  
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Utility.log("Thread " + nThreadID + " is over!"); MtS
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bDownOver = true; S}(8f!9<  
//nPos = fileAccessI.write (b,0,nRead); }GumpT$Xw  
} )p<WDiX1!e  
catch(Exception e){e.printStackTrace ();} + WVIZZ8  
} F]UQuOR)  
} QT! 4[,4  
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xl(@C*.sC1  
//打印回应的头信息 `ltN,?/  
public void logResponseHead(HttpURLConnection con) <Mx0\b!  
{ [}OgSP9i  
for(int i=1;;i++) :_ROJ  
{ %f j+70  
String header=con.getHeaderFieldKey(i); {%C*{,#+8q  
if(header!=null) G?AG:%H%  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); <A>)[u  
Utility.log(header+" : "+con.getHeaderField(header)); .Obn&S  
else
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break; K_~h*Yc  
} <[Q3rJ  
} *)<B0SjT  
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public void splitterStop() D-2.fjo9!  
{ 7Vu?  
bStop = true; qH>`}/,P  
} "T2"]u<52  
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} hA}~es=c  
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/* iCj2"T4TN  
**FileAccess.java r@U3sO#N  
*//文件访问(定位，写) %c|UmKKi  
package NetFox; (Glr\q]jF\  
import java.io.*; =PkO!Mm8  
r X'*|]  
7j$Pt8$  
public class FileAccessI implements Serializable{ ehNzDr\s  
tz^/J=)"  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Y^KTkS0D  
RandomAccessFile oSavedFile; uR;gVO+QC  
long nPos; #m<tJnEO  
M;w?[yEZ  
:~F:/5
 
public FileAccessI() throws IOException 59r_#(uo  
{ K+Y^>N4m  
this("",0); -d+aV1n  
} oVvc?P  
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@L/o\pvc  
public FileAccessI(String sName,long nPos) throws IOException @I`C#~  
{ R=Zn -q  
oSavedFile = new RandomAccessFile(sName,"rw"); 7F^#o-@=J  
this.nPos = nPos; {ZU1x C  
oSavedFile.seek(nPos); kDvc" ,SD#  
} 0AK,&nbF  
1'.7_EQ4T  
{@W9
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public synchronized int write(byte[] b,int nStart,int nLen) .Jx9bIw  
{ hRC
 
int n = -1; h `}}  
try{ *&BnF\?m  
oSavedFile.write(b,nStart,nLen); V7d)S&*V  
n = nLen; *NFg;<:j  
} )s_n  
catch(IOException e) cD*}..-/4  
{ lot%N(mB`  
e.printStackTrace (); kIHDe
o%K}  
} <%.5hCTp97  
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return n; qfY5Ww$8  
} o+w;PP)+=  
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} Jn:ZYqc  
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{S/yL[S.  
/* 6!x&LoM  
**SiteInfoBean.java vo>d!rVCV  
*/ `?T#Hl>j  
package NetFox; l^GP3S  
W1fW}0   
1"Z@Q`}  
public class SiteInfoBean { }En  
|-sPLU&s%  
L86n}+ P\  
private String sSiteURL; //Site's URL
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private String sFilePath; //Saved File's Path glDcUCF3  
private String sFileName; //Saved File's Name W} WI; cI  
private int nSplitter; //Count of Splited Downloading File b@RHc!,>jV  
vEf4HZ&w  
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public SiteInfoBean() 8
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{//nSplitter的缺省值为5 QaUm1i#
 
//default value of nSplitter is 5 zp\8_U@  
this("","","",5); 9T#;,{VQ  
} ~wg:!VWA)  
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u]}s)SmDk  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) J>fQNW!{  
{ "KcA  
sSiteURL= sURL; ;iDPn2?6?x  
sFilePath = sPath; 21k5I #U  
sFileName = sName; )`^p%k  
this.nSplitter = nSpiltter; ^u3V E  
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} <ZU=6Hq  
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 >S$Z  
public String getSSiteURL() *#TUGfwy  
{ a0r"N[&  
return sSiteURL; THmb
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} LC1(Xbf  
 XL7h}  
pp9Zb.D\  
public void setSSiteURL(String value) AwQ?l(iZ"p  
{ !w&kyW?e  
sSiteURL = value; H'Yh2a`!o  
} GhPK-+"X  
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public String getSFilePath()
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{ 0uBl>A7qhn  
return sFilePath; {Zp\^/  
} B]tIi^  
lJ@][;  
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public void setSFilePath(String value) &=4(l|wcg  
{ >E*$ E  
sFilePath = value; 'M3">$N  
} vTv]U5%:>%  
b(9FZ]7S  
{3&|tk!*  
public String getSFileName() CKA;.sh  
{ ZyE
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return sFileName; .7n\d55a  
} t(="h6i  
~F1:N>>_Cf  
p ;|jI1  
public void setSFileName(String value) vf8\i-U=  
{ EM\'GW  
sFileName = value; fryJW=  
} g[w,!F  
%Q!`NCe+[  
}x&N^Ky3c  
public int getNSplitter() [~&X
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{ bGorH=pb5R  
return nSplitter; v!%5&: c3  
} 1Z,[|wJ  
`_&Vt=7lG  
bO<CR  
public void setNSplitter(int nCount) 1 E22R  
{ <7Ae-!>x  
nSplitter = nCount; z)uuxNv[R  
} I2H6y"pN  
} \lSU  
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/* _sbp6ZO_  
**Utility.java 3"{.37Q  
*/ [xKd7"d/n  
package NetFox; mXXt'_"  
n#iwb0-  
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public class Utility { SRSvot};C  
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public Utility() %e@#uxm  
{ )$,"u4  
:f$xQr4Qz  
HE
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} a/< Csad  
>fIk;6
<{  
//线程睡眠 ;.bm6(;  
public static void sleep(int nSecond) *FJZiPy
 
{ BT@r!>Nl  
try{ &Ni`e<mP  
Thread.sleep(nSecond); bz| D-.  
} $k$4% 7  
catch(Exception e) "HXYNS>  
{ $t/x;<.H  
e.printStackTrace (); \8uIER5)  
} nF5qw>t#  
} 72veLB  
)P|[r  
//日志 O=9-Qv|  
public static void log(String sMsg) 5cWw7V<m  
{ tbO H#|  
System.err.println(sMsg); z;u  
} b9XW9O`B  
]#.]/f >-  
!*`-iQo&  
public static void log(int sMsg) *~/OOH$"  
{  RDtU43  
System.err.println(sMsg); DvM5 k  
} ,y%3mR_~  
} Iz[@^IUx=  
%e@HZ"V  
A0%}v*  
/* 6K-5g/hL  
**TestMethod.java W14Vm(`N  
*/ @X3{x\i'I  
package NetFox; i%6;  
hkOsm6  
N D<HXO  
public class TestMethod { fQP{|+4  
?3O9eZY@  
G7=pBf  
public TestMethod() [le)P$#z  
{ ///xx/weblogic60b2_win.exe MaD3[4@#  
try{ u=YX9M
o!  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); B(F,h+ajy  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); +7
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SiteFileFetch fileFetch = new SiteFileFetch(bean); = P   
fileFetch.start(); 7n90f2"m  
} 2!Bd2  
catch(Exception e){e.printStackTrace ();} #Oha(mRY  
x2QIPUlf  
D3c2^r$Z  
} IL_d:HF|1  
<9sO  
,E|m.  
public static void main(String[] args) F:#J:x'  
{ hva2o`  
new TestMethod(); 45&8weXO:'  
} *.&HD6Qr  
} qT/Do?Y  
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