http断点续传简单实现（java)

/* S([
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**SiteFileFetch.java mZ%\`H+  
*/ re2%e-F"  
package NetFox; 1owoh,V6  
import java.io.*; 6ZJQ '9f  
import java.net.*; 7Q&P4{hi0  

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public class SiteFileFetch extends Thread { I-I5^s  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 9EW 7,m{A  
long[] nStartPos; //开始位置 L M[<?`%p  
long[] nEndPos; //结束位置 |,crQ'N'  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 }W J`q`g  
long nFileLength; //文件长度 Urr1K)  
boolean bFirst = true; //是否第一次取文件 eX/$[SL[  
boolean bStop = false; //停止标志 U
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File tmpFile; //文件下载的临时信息 ~Hf,MLMdTf  
DataOutputStream output; //输出到文件的输出流 |ipppE=  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 'tj4;+xf^  
public SiteFileFetch(SiteInfoBean bean) throws IOException IG\\RYr  
{ /e,lD)  
siteInfoBean = bean; Hqk2W*UTl  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); )sr]}S0  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ] D(3   
if(tmpFile.exists ()) ;DOz92X
94  
{ TfOZ>uR"g  
bFirst = false; %]` WsG  
read_nPos(); pD9c%P  
} +J}M$eQ  
else 8,Z0J  
{ 6Xa2A6  
nStartPos = new long[bean.getNSplitter()]; uB
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nEndPos = new long[bean.getNSplitter()]; b~p <  
} 
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} ? "gy`oCv  
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public void run() d>}%A ]  
{ 4C$,X!kzF  
//获得文件长度 _<8y^y
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//分割文件 @QEVl
 
//实例FileSplitterFetch s
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//启动FileSplitterFetch线程 , /pE*Yk  
//等待子线程返回 ! ^W|;bq  
try{ r]yq #T`z  
if(bFirst) ,^(T^ -  
{ ,DjZDw  
nFileLength = getFileSize(); u'C4d6\wS  
if(nFileLength == -1) .T7ciD  
{ Kj7Osqu2bE  
System.err.println("File Length is not known!"); hH\(>4l  
} Zo`^pQS  
else if(nFileLength == -2) )xeVoAg  
{ t t=$:}A  
System.err.println("File is not access!"); t%%I.zIV7  
} `u-}E9{  
else lZ|
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{ &xVWN>bd^  
for(int i=0;i<nStartPos.length;i++) !dGgLU_  
{ 9D bp`%j  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Kr<O7t0X  
} 6\bbP>ql  
for(int i=0;i<nEndPos.length-1;i++) s}.nh>Q  
{ Hi9]M3Ub  
nEndPos = nStartPos[i+1]; OCd[P1Y]  
} _MR2,mC  
nEndPos[nEndPos.length-1] = nFileLength; >2rFURcD  
} J]%P fWV  
} `U1"WcN  

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//启动子线程 zAH+{4lC+  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; biJU r^n  
for(int i=0;i<nStartPos.length;i++) %u
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{ t :_7O7  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), wNPZ[V:  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), |(/"IS]  
nStartPos,nEndPos,i); F"q3p4-<>  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1)%o:Xy o  
fileSplitterFetch.start(); </fnbyGR  
} w-KtxG(  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), QMIQy  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); BdceINI  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $6_J`7  
nEndPos = " + nFileLength); \6N\6=t!A  
// fileSplitterFetch[nPos.length-1].start(); ?TXFOr]g]2  
bx@CzXre;  
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//等待子线程结束 6Hz=VhQrN  
//int count = 0; f7`y*9^  
//是否结束while循环 sU8D;ML7  
boolean breakWhile = false; Qcw/>LaL:  
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while(!bStop) BKIt,7j  
{ a; "+Py  
write_nPos(); 27MgwX NQ  
Utility.sleep(500); %VdJ<=@  
breakWhile = true; qP"m819m  
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for(int i=0;i<nStartPos.length;i++) .
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{ a+X X?uN{  
if(!fileSplitterFetch.bDownOver) a\zbi$S  
{ r1[0#5kJ;J  
breakWhile = false; 2]7nw1&  
break; !,\]> c  
} N=wB1gJ  
} 5%Q!R%  
if(breakWhile) A}%sF MA  
break; 8mV35A7l  
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//count++; q[+];  
//if(count>4) , w_Ew  
// siteStop(); shi#K<gVC  
} eVy,7goh  
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8T%z{A1T  
System.err.println("文件下载结束！"); old}}>_  
} <mpkkCl,  
catch(Exception e){e.printStackTrace ();} ;xb:{?  
} EZ$m4:{e  
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//获得文件长度 AttDD{Ta  
public long getFileSize() ^@N@
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{ fQv^=DI#  
int nFileLength = -1; L:S[QwQu8  
try{ <5nz:B
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URL url = new URL(siteInfoBean.getSSiteURL()); $
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
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httpConnection.setRequestProperty("User-Agent","NetFox"); s Ce{V*ua  

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int responseCode=httpConnection.getResponseCode(); SL*B `P~{  
if(responseCode>=400) @P%&Dha  
{ wL}=$DN  
processErrorCode(responseCode); TEY%OIzU+  
return -2; //-2 represent access is error M*t{?o/t;  
} RhYf+?2  
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String sHeader; chxO*G  
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for(int i=1;;i++) l2$6ojpo  
{ Peb;XI
 
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); dC)@v]#h  
//Utility.log(in.readLine()); GUMO;rZs  
sHeader=httpConnection.getHeaderFieldKey(i); ?-6oh~W<  
if(sHeader!=null) z0c_&@uj*  
{ 8)T.[AP  
if(sHeader.equals("Content-Length")) >R :Bkf-  
{ O[$&]>x]]  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 8E|S`I  
break; (A?/D!y  
} wVp  
} edA.Va|0  
else :dB6/@fW  
break; x%0Q W  
} 40mgB4I  
} m&fm<?|  
catch(IOException e){e.printStackTrace ();} U"/":w ~  
catch(Exception e){e.printStackTrace ();} >8E
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Utility.log(nFileLength); O9jqeF`L=  
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return nFileLength; 10t9Qv/  
} S)p1[&" M  
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8
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//保存下载信息（文件指针位置） ;jS~0R  
private void write_nPos()
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{ Ub0g{   
try{ iku) otUc  
output = new DataOutputStream(new FileOutputStream(tmpFile)); aO6w:IO  
output.writeInt(nStartPos.length); RP!X5  
for(int i=0;i<nStartPos.length;i++) %i$]S`A}  
{ F~4oPB K<  
// output.writeLong(nPos); BlMc<k  
output.writeLong(fileSplitterFetch.nStartPos); cjp H hoW  
output.writeLong(fileSplitterFetch.nEndPos); n-0RA~5z  
} $fL2w^ @  
output.close(); "/g/Lc  
} a
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catch(IOException e){e.printStackTrace ();} ^GHA,cSf  
catch(Exception e){e.printStackTrace ();} qE!.C}L+  
} ,~>A>J  
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//读取保存的下载信息（文件指针位置） \= =rdW-  
private void read_nPos() 8 Zhx&  
{ *+rO3% ;t  
try{ ;(5b5PA  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); iW9G0Ay  
int nCount = input.readInt(); '+JU(x{CCl  
nStartPos = new long[nCount]; N8_ c%6GE  
nEndPos = new long[nCount]; rK7m(  
for(int i=0;i<nStartPos.length;i++) 9Eu.Y
 
{ 5Ay\s:hb[u  
nStartPos = input.readLong(); F=bX\T7  
nEndPos = input.readLong(); *;5P65:u$>  
} 1#/>[B  
input.close(); <XDYnWz  
} &3#19v7/  
catch(IOException e){e.printStackTrace ();} x(ue |UG  
catch(Exception e){e.printStackTrace ();} /J9|.];%r  
} vu V
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private void processErrorCode(int nErrorCode) tY'fFz^Ho  
{ 2Sz?r d,0f  
System.err.println("Error Code : " + nErrorCode); Bs:INvhYW  
} R9xhO!  
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g 67;O(3  
//停止文件下载 ~|QhWgq  
public void siteStop() P;GRk6  
{ ER-X1fD  
bStop = true; gn4+$f~w  
for(int i=0;i<nStartPos.length;i++) gE;r;#Jt4  
fileSplitterFetch.splitterStop(); C3>&O?7J*7  
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} _!2bZ:emG  
} XA PqRJ*Z  
//负责部分文件的抓取 mhpaPin*JS  
**FileSplitterFetch.java %zsY=qT  
*/ @A?Ss8p'  
package NetFox; tX)l_?jVH  
%s&l^&
ux  
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import java.io.*; ny'?Hl'Q  
import java.net.*; J'4Pp<  
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public class FileSplitterFetch extends Thread { QmxI;l  
/z
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;=r_R!
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String sURL; //File URL p`N+9t&I4  
long nStartPos; //File Snippet Start Position fXD9w1  
long nEndPos; //File Snippet End Position >JVdL\3  
int nThreadID; //Thread's ID ~$w9L998+  
boolean bDownOver = false; //Downing is over zp.-=)D4e  
boolean bStop = false; //Stop identical tr?U/YG  
FileAccessI fileAccessI = null; //File Access interface e,V @t%  
;xqN#mqq  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException z'"e|)  
{ Es]:-TR  
this.sURL = sURL; !:BmDX[<n  
this.nStartPos = nStart; ?5VPV9EX  
this.nEndPos = nEnd;
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nThreadID = id; ^W#161&  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 y
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} `|&#=hl~  
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public void run() C6` Tck!  
{ UmEc")3  
while(nStartPos < nEndPos && !bStop) b;xn0sDn#  
{ s
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try{ ~$PY6s  
URL url = new URL(sURL); 8@rddk  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Ar{7H)V:  
httpConnection.setRequestProperty("User-Agent","NetFox"); Rq@M~;p  
String sProperty = "bytes="+nStartPos+"-"; (Y!{ UNq5  
httpConnection.setRequestProperty("RANGE",sProperty); +YD_ L  
Utility.log(sProperty); 0)Nu  
+%sMd]$,n  
/
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InputStream input = httpConnection.getInputStream(); CNMcQP  
//logResponseHead(httpConnection); VPi*9(LS  
&dsXK~9M>  
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byte[] b = new byte[1024]; i(O+XQ}Fyx  
int nRead; 2p|ed=ly%  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) )JA9bR <  
{ y?Cq{(  
nStartPos += fileAccessI.write(b,0,nRead); 2r^G;,{  
//if(nThreadID == 1) ;X;q8J^_K_  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); {J~VB~('  
} OrPi ("/  
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$ VTk0J-W  
Utility.log("Thread " + nThreadID + " is over!"); u;G-46  
bDownOver = true; 2QIx~Er  
//nPos = fileAccessI.write (b,0,nRead); Ci9]#)"c  
} %n B}Hq ;  
catch(Exception e){e.printStackTrace ();} hEhvA6f,  
} <rI8O;\H  
} C.`!?CW  
*N65
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\p.eY)>  
//打印回应的头信息 G
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public void logResponseHead(HttpURLConnection con) bDtb"V8e  
{ %LjhK,'h  
for(int i=1;;i++) \%/Y(YVm  
{ &"6%D|Z0  
String header=con.getHeaderFieldKey(i); +bdjZD3  
if(header!=null) L)"E_  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); FE'F@aS\  
Utility.log(header+" : "+con.getHeaderField(header)); 1
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else |SX31T9rG  
break; RLNto5?  
} Vw";< <0HZ  
} Mwtd<7<!A  
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$+WMKv@<  
public void splitterStop() IeT1Jwe  
{ ]@A31P4t|  
bStop = true; }cO}H2m  
} \f4JIsZ-&  
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} \5DOp-2  
 ovsI2  
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/* \Xpq=2`  
**FileAccess.java jM[]Uh  
*//文件访问(定位，写) uRnSwJ"hE  
package NetFox; ?#gYu%7DN  
import java.io.*; >A.m`w  
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fI }v}L^  
public class FileAccessI implements Serializable{ <IwfiI3y  
 %Z-B{I(  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 =bh.V@*  
RandomAccessFile oSavedFile; ~]78R!HJ  
long nPos; <G60R^o  
i p; RlO  
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public FileAccessI() throws IOException lG R6S  
{ chszP{-@X  
this("",0); bM>5=Zox  
} T:0#se  
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public FileAccessI(String sName,long nPos) throws IOException ay>u``$R  
{ ,}23  
oSavedFile = new RandomAccessFile(sName,"rw"); XK,l9 {*  
this.nPos = nPos; ;@s'JSPt  
oSavedFile.seek(nPos); nO;t5d  
} $E6bu4I  
JAU:Wqlg1  
bR}=bp4K  
public synchronized int write(byte[] b,int nStart,int nLen) f0ME$:2  
{ VQ/Jz5^  
int n = -1; " "{#~X}  
try{ Zp_v
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oSavedFile.write(b,nStart,nLen); EL:Az~]V  
n = nLen; uoMDf{d  
} [`U9
  
catch(IOException e) dW9Ci"~v  
{ g1(`a`M  
e.printStackTrace (); gaVQ3NqF  
} cUD}SOW  
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return n; CAtdx!  
} TKrh3   
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} $[M5Vv  
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~O~R,h>  
/* p?Jx2(%m  
**SiteInfoBean.java ,+o*>fD  
*/ W8Aii'Q8C/  
package NetFox; wJ>2}  
&!KW[]i%9}  
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public class SiteInfoBean { *c'hmAs  
`>N_A!pr`  
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private String sSiteURL; //Site's URL 7!jbID~  
private String sFilePath; //Saved File's Path BjAmM*k  
private String sFileName; //Saved File's Name M'}iIO`L  
private int nSplitter; //Count of Splited Downloading File 3}V-'!  
cRS2v--\-  
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public SiteInfoBean() (C60HbL  
{//nSplitter的缺省值为5 zMbz_22*  
//default value of nSplitter is 5 65AG#O5R  
this("","","",5); D9-D%R,
 
} D/TEx2.=J3  
G;yh$n<"  
f) @-X!  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ^gd[UC-"w  
{ 2Pic4Z  
sSiteURL= sURL; jLCZ JSK  
sFilePath = sPath; :}3;z'2]l  
sFileName = sName; [RFF&uy  
this.nSplitter = nSpiltter; \iM  
6U[bAp  
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}  >q^l  
nWb0S  
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public String getSSiteURL() |nq}#  
{ V>:ubl8j0l  
return sSiteURL; ]}HuK#  
} mrId`<L5l{  
6ujePi <U  
#P5tTCM  
public void setSSiteURL(String value) !/wR[`s9w  
{ E'wJ+X9 +  
sSiteURL = value; ar[*!:!  
} =6^phZ(  
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\&.]!!Q  
public String getSFilePath() 1k?k{Ri  
{ iES?}K/q  
return sFilePath; a@}A;y'd  
} %VmHw~xyF:  
0 V3`rK  
e QGhX(  
public void setSFilePath(String value) oY8S-N;(t  
{ 9~6)u=4sS"  
sFilePath = value; N_eZz#);  
} *g~\lFX,u  
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public String getSFileName() C,#FH}  
{ \\9$1yg  
return sFileName; ?
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} |)+;d  
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public void setSFileName(String value) "*N=aHsj  
{ Kt\#|-{CH-  
sFileName = value; T~JE.Y3B3  
} 1@vlbgLr@  
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public int getNSplitter() L-QzC<[F/  
{ ;!H|0sv  
return nSplitter; b$k|D)_|  
} Cp[ NVmN  
bL"!z"NA  
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public void setNSplitter(int nCount) M^3pJ=;5  
{ qt{{q  
nSplitter = nCount; RJO40&Z<Z  
} v cZg3:j  
} :UDT! 5FNO  
2!E@Gbhm5  
q#!]5
 
/* JOvRUDZ  
**Utility.java <C6*-j1oz  
*/ AHl1{* [  
package NetFox; [d}AlG!  
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F|3iKK022  
public class Utility { /Xo8 kC  
u[;,~eB%w  
**!  
public Utility() Gn7P` t*.  
{ mpysnKH  
= gbB)u-Pc  
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} 9/_F  
\n`)>-  
//线程睡眠 AQ` `Dp  
public static void sleep(int nSecond) !Ey=  
{ 3sy|pa  
try{ r}]%(D](v  
Thread.sleep(nSecond); W`2Xn?g  
} Y&JK*d  
catch(Exception e) n13#}i{tm  
{ "x P2GZ  
e.printStackTrace (); 1*o=I-nOa  
} l=.h]]`;  
} MrGq{,6C  

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//日志 XwNJHOaF  
public static void log(String sMsg) 5B76D12  
{ C~:@ETcbil  
System.err.println(sMsg); DtrR< &m  
} ~vMdIZ.h  
$VRVMY [q  
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public static void log(int sMsg) 4' MmT'  
{ y +2  
System.err.println(sMsg); ]#*S. r]  
} 2\/,X CQV  
}  5gZ6H/.  
]:X# w0UR  
Tb@r@j:V  
/* IqW4Q1>f  
**TestMethod.java *~>}*  
*/ Ub_!~tb}?  
package NetFox; ].e4a;pt  
!/;/ X\d  
7u|X .X  
public class TestMethod { Z|k>)pv@  
t5"g9`AL  
UG5AFZ\  
public TestMethod() i3[%]_eP.  
{ ///xx/weblogic60b2_win.exe lNwqWOWy  
try{ T1YCld  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); m2|%AD  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5);
6 J B"qd  
SiteFileFetch fileFetch = new SiteFileFetch(bean); pSC\[%K  
fileFetch.start(); 4 [K"e{W3  
} o,D7$WzL  
catch(Exception e){e.printStackTrace ();} <jwQ&fm)/R  
8uq`^l%KkZ  
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} =}1)/gcM  
uihU)]+@t/  
7kDqgod^A  
public static void main(String[] args) 1](PuQm7+  
{ "AcC\iq  
new TestMethod(); suF<VJ)&s  
} ](2\w9i%  
} L)qDtXd4  
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