http断点续传简单实现（java)

/* > voUh;L  
**SiteFileFetch.java %%3ugD5i!  
*/ /y-P)3_  
package NetFox; X:!%"K%}  
import java.io.*; "xO`&a{  
import java.net.*; #/1Bam6
 
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public class SiteFileFetch extends Thread { ~\kRW6  
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SiteInfoBean siteInfoBean = null; //文件信息Bean dZYS5_wr  
long[] nStartPos; //开始位置 -+4$W{OK*0  
long[] nEndPos; //结束位置 0loC^\f  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 \m\.+q]  
long nFileLength; //文件长度 ?IWLl  
boolean bFirst = true; //是否第一次取文件 L NE]#8ue  
boolean bStop = false; //停止标志 {&4qknPd%  
File tmpFile; //文件下载的临时信息 $Z,+aLmb  
DataOutputStream output; //输出到文件的输出流 mee-Qq:}  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） !#?tA/t@  
public SiteFileFetch(SiteInfoBean bean) throws IOException +tA rH C]  
{ 9wwvh'T&NK  
siteInfoBean = bean; ,on
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ~KNxAxyVi  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 3&zmy'b*:  
if(tmpFile.exists ()) f2Slsl;
 
{  C[Fh^  
bFirst = false; zZ wD)p?_g  
read_nPos(); CkflEmfe  
} #&/*ll)  
else iN)@Cu7  
{ Gmc"3L  
nStartPos = new long[bean.getNSplitter()]; yZ  P
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nEndPos = new long[bean.getNSplitter()]; |_rj12.xo  
} q<UqGj7#   
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} ILpB:g  
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public void run() N" 8o
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{ aL`pvsn
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//获得文件长度 t3WlVUtq3  
//分割文件 $ OR>JnV  
//实例FileSplitterFetch f9rToH  
//启动FileSplitterFetch线程 yw
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//等待子线程返回 \\T I4A^#  
try{ p 2i5/Ly  
if(bFirst) b9vKux  
{ (=\P|iv  
nFileLength = getFileSize(); C6Mb(
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if(nFileLength == -1) W=b5{ 6  
{ {jl4`  
System.err.println("File Length is not known!"); ^aC[ZP:  
} HC0puL
t_  
else if(nFileLength == -2) jgYiuM3c\  
{ _]4cY%s  
System.err.println("File is not access!"); WV6vM()#!C  
} vrbS-Z<S9  
else wx1uduT)  
{ v#X? KqD  
for(int i=0;i<nStartPos.length;i++) sM4wh
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{ 1TVTP2&Rd  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); BAPi<U'D  
} "-Ns1A8  
for(int i=0;i<nEndPos.length-1;i++) l nZ=< T  
{ vKW%l  
nEndPos = nStartPos[i+1]; ;L`'xFo>>  
} m&x0
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nEndPos[nEndPos.length-1] = nFileLength; C

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} 'D-imLV<<  
} RDZq(rKc  
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//启动子线程 ^\CQWgY(  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; (&B
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for(int i=0;i<nStartPos.length;i++) b)V[
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{ MHbRG_zW  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Rl)/[T  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), E*ic9Za8`h  
nStartPos,nEndPos,i); 9-@w(kMu  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _S[H:b$?  
fileSplitterFetch.start(); (u*]&yk  
} QL)UPf>Kp  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), '5Y8 rv<  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); <wuP*vI"h  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", f;b(W  
nEndPos = " + nFileLength); toCN{[   
// fileSplitterFetch[nPos.length-1].start(); >Kr,(8rA  
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U/ZbE?it>  
//等待子线程结束 }C'z$i( y  
//int count = 0; 6>"0H/y,  
//是否结束while循环 lDH0bBmd0  
boolean breakWhile = false; h!Ka\By8#  
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qmK!d<4  
while(!bStop) "L,FUo^&  
{ cVz.ac  
write_nPos(); W$3p,VTMmB  
Utility.sleep(500); ?T^$,1-  
breakWhile = true; 6^zv:C%  
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for(int i=0;i<nStartPos.length;i++) ctCfLlK  
{ )~5`A*Ku  
if(!fileSplitterFetch.bDownOver) $DMeUA\av  
{ #e#8I7P  
breakWhile = false; ;6]+/e7O  
break; *L^{p.K4  
} =tP|sYR]^  
} Ri,UHI4 W  
if(breakWhile) }ri"u;.R  
break; \Lc pl-;?  
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//count++; mr/^lnO  
//if(count>4) 1xx-}AIH#  
// siteStop(); jeW0;Cz J~  
} fer'2(G?W  
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System.err.println("文件下载结束！"); "NJ!A  
} L*5&hPU  
catch(Exception e){e.printStackTrace ();} Og,,s{
\  
} u'N'<(\k  
9 ROKueP  
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//获得文件长度 ,mRN;|N  
public long getFileSize() qH-dT,`"{  
{ weu'<C   
int nFileLength = -1; bT>^% H3  
try{ l"MEX/  
URL url = new URL(siteInfoBean.getSSiteURL()); K=~h1qV:  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); b\^.5SEw  
httpConnection.setRequestProperty("User-Agent","NetFox"); /fD)/x  
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int responseCode=httpConnection.getResponseCode(); h)YqC$A-s  
if(responseCode>=400) p<![JeV  
{ wRuJein#  
processErrorCode(responseCode); YsTfv1~z#  
return -2; //-2 represent access is error
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} X&McNO6"  
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String sHeader; c XY!b=9  
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for(int i=1;;i++) ad"&c*m[  
{ PM_q"}-  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Fc nR}TE  
//Utility.log(in.readLine()); Ck[Z(=b$$:  
sHeader=httpConnection.getHeaderFieldKey(i); 9@S icqx   
if(sHeader!=null) oACE:h9U  
{ <H 3}N!  
if(sHeader.equals("Content-Length")) :Ct}||9/  
{ c\R!z&y~  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 9(H8MUF0{  
break; K_My4>~Il  
} 7tyn?t0n  
} nVYh1@yLy  
else G q:7d]c~T  
break; )`U T#5  
} sd=i!r)ya  
} gz$=\=%>RL  
catch(IOException e){e.printStackTrace ();} yP"_j&ef7  
catch(Exception e){e.printStackTrace ();} is`a_{5e=  
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Utility.log(nFileLength); Nl(Aa5:!  
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return nFileLength; jm*v0kNy  
} a @TAUJ,  
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//保存下载信息（文件指针位置） G&;W  
private void write_nPos() eR3!P8t  
{ ~=c#Ff=Z  
try{ 1&m08dZm5  
output = new DataOutputStream(new FileOutputStream(tmpFile)); N/y.=]  
output.writeInt(nStartPos.length); 5v?6J#]2  
for(int i=0;i<nStartPos.length;i++) |_ ;-~bmb  
{ n,fUoS  
// output.writeLong(nPos); RJg# A`  
output.writeLong(fileSplitterFetch.nStartPos); n'R 8nn6^  
output.writeLong(fileSplitterFetch.nEndPos); V6Q[Y>84~a  
} $+rdzsf)+/  
output.close(); .Wb),  
} ,@2O_O`:  
catch(IOException e){e.printStackTrace ();} 2 OGg`1XX  
catch(Exception e){e.printStackTrace ();} aUJ&  
} q!FJP9x  
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//读取保存的下载信息（文件指针位置） KJ~f~2;  
private void read_nPos() kiXa2Yn*(d  
{ Bg34YmZ  
try{ m2 OP=z@)  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Ot/Y?=j~  
int nCount = input.readInt(); 7$w:~VZ  
nStartPos = new long[nCount]; <;acWT?(  
nEndPos = new long[nCount]; 2Gx&ECa,  
for(int i=0;i<nStartPos.length;i++) #$#{QEh0}  
{ mDo]5 i<  
nStartPos = input.readLong(); T%ha2X=  
nEndPos = input.readLong(); / P{f#rV5  
} ZL@7Mr!e  
input.close(); )ll}hGS  
} R(hqBa/V  
catch(IOException e){e.printStackTrace ();} M>'-P  
catch(Exception e){e.printStackTrace ();} lv{Qn~\y&  
} n2TvPt\  
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private void processErrorCode(int nErrorCode)  Kp!P/Q{  
{ E]+W^VG  
System.err.println("Error Code : " + nErrorCode); Ot(EDa9}IJ  
} zf^!Zqn[8z  
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//停止文件下载 9WHkw@<R+  
public void siteStop() |>p\*Dl}H  
{  g\n@(T$)  
bStop = true; }z[O_S,X  
for(int i=0;i<nStartPos.length;i++) `< VoZ/v  
fileSplitterFetch.splitterStop(); YwKY3kL  
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} Amz7j8zJ  
} =`{!" 6a  
//负责部分文件的抓取 S6Kaw  
**FileSplitterFetch.java N>@AsI  
*/ F-2HE><+  
package NetFox; Oa*/jZjr  
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import java.io.*; XD*$$`+#  
import java.net.*; d<#Xqc  
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public class FileSplitterFetch extends Thread { 6)Oe]{-  
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String sURL; //File URL d~YDg{H  
long nStartPos; //File Snippet Start Position O^ f[ugs  
long nEndPos; //File Snippet End Position `qX'9e3VP+  
int nThreadID; //Thread's ID B
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boolean bDownOver = false; //Downing is over 2\m+  
boolean bStop = false; //Stop identical gpO@xk$  
FileAccessI fileAccessI = null; //File Access interface !a?o9<V  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException #{<Jm?sU  
{ 2,dGRf  
this.sURL = sURL; .XS rLb?  
this.nStartPos = nStart; R1?g6. Mq  
this.nEndPos = nEnd; jtl7t5
9R  
nThreadID = id; lHZf'P_Wx  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 o#E z_D[  
} Pbz-I3+66  
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public void run() dB< \X.   
{ y?Fh%%uNr  
while(nStartPos < nEndPos && !bStop) Z\TH=UA  
{ u5%.T0 P  
l6)*u[}E  
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try{ TB1 1crE  
URL url = new URL(sURL); eF:6k qg  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~I2IgEj>]  
httpConnection.setRequestProperty("User-Agent","NetFox"); |1;0q<Ka  
String sProperty = "bytes="+nStartPos+"-"; O8n\>pkI  
httpConnection.setRequestProperty("RANGE",sProperty); UB?a-jGZK  
Utility.log(sProperty); 'ApWYt  
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InputStream input = httpConnection.getInputStream(); 0Ac]&N d`  
//logResponseHead(httpConnection); dH?;!sJ  
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byte[] b = new byte[1024]; |PTL!>ym2  
int nRead; /q(+r5k \  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) #jK{)%}mA  
{ yQ6{-:`)  
nStartPos += fileAccessI.write(b,0,nRead); 9/q4]%`  
//if(nThreadID == 1) ~M,n
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); /.Gx n0  
} _ ?=bW  
!P#lTyz  
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Utility.log("Thread " + nThreadID + " is over!"); $wC]S4C  
bDownOver = true; N2=gSEY  
//nPos = fileAccessI.write (b,0,nRead); /ijj;9EB  
} oP_'0h0X  
catch(Exception e){e.printStackTrace ();} e)>Z&e,3  
} SIzW3y[  
} a&4>xZU #  
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//打印回应的头信息  =DvnfT<  
public void logResponseHead(HttpURLConnection con) sj
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{ 3E:wyf)i"  
for(int i=1;;i++) A+NLo[swwu  
{ ,8EeSnI  
String header=con.getHeaderFieldKey(i); )7[>/2aGd  
if(header!=null) ka*VQXk*  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); '2v,!G]^  
Utility.log(header+" : "+con.getHeaderField(header)); n%@xnB$ZX  
else )T 3y,*  
break; d v"  
} x)nBy)<  
} lOcvRF  
/dBQ*f5  
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public void splitterStop() t9W_ [_a9  
{ R&=Y7MfZ  
bStop = true; 44($a9oa2  
} !j(v-pQf"  
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} e,|"9OK  

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/* /V-7u  
**FileAccess.java qEX59v  
*//文件访问(定位，写) }=;N3Q" #y  
package NetFox; hH`yQGZ  
import java.io.*; 5H;*Nj@  
<fWho%eOK  
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public class FileAccessI implements Serializable{ );7csh%  
)xlNj$(x5n  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 c"77<Db$  
RandomAccessFile oSavedFile; __'Z0?.4#  
long nPos; F2OU[Z,-]  
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N  
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public FileAccessI() throws IOException FL"IPX;
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{ 1m|1eAGS{  
this("",0); PBR+NHrZ  
} H Viu7kue`  
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public FileAccessI(String sName,long nPos) throws IOException }DY^a'wJ-  
{ boJQ3Xc  
oSavedFile = new RandomAccessFile(sName,"rw"); NS mo(c>5  
this.nPos = nPos; ~iydp  
oSavedFile.seek(nPos); N@Bqe{r6j  
} YtxBkKiJ2V  
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}0}J  
public synchronized int write(byte[] b,int nStart,int nLen) : :e=6i  
{ V]`V3cy1+3  
int n = -1; !V7VM_}@Y  
try{ ^7~=+0cF]  
oSavedFile.write(b,nStart,nLen); mJ !}!~:  
n = nLen; A\.k['!  
} <@(HQuL#  
catch(IOException e) JwxI8Pi*y  
{ >")%4@  
e.printStackTrace (); a}El!7RO0  
} (;V]3CtU*  
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return n; ~u/Enl7\-  
}  @X  
at ]Lz_\  
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} GDZe6*  
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4,wdIdSm4  
/* (gs"2  
**SiteInfoBean.java gP^'4>Jr  
*/ >x(^g~i  
package NetFox; mzfj!0zR*  
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,r:. 3.  
public class SiteInfoBean { ([`-*Hy  
W5EB+b49KM  
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private String sSiteURL; //Site's URL `{ou4H\  
private String sFilePath; //Saved File's Path \[+ZKj:  
private String sFileName; //Saved File's Name 80c\O-{  
private int nSplitter; //Count of Splited Downloading File akr
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N;;!ObVHnP  
Z!^iPB0~D  
public SiteInfoBean() d+[hB4!l2  
{//nSplitter的缺省值为5 YmNBtGhT  
//default value of nSplitter is 5 W(a=ev2sa  
this("","","",5); O9:vPbn  
} F~)xZN3=  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Bn-%).-ED  
{ Zb<DgJ=3  
sSiteURL= sURL; SN\;&(
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sFilePath = sPath; =DcKHL(m  
sFileName = sName; P;mmK&&  
this.nSplitter = nSpiltter; )7*Apy==x  
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} Z:u7`%  
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: R.,<DQM  
public String getSSiteURL() %~}9#0h)  
{ 7?Xfge%\  
return sSiteURL; e9o(hL  
} Cq}LKiu  
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public void setSSiteURL(String value) ;UArDwH  
{ M5[AA/@  
sSiteURL = value; "72 _Sw  
} ^#vWdOlt  
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public String getSFilePath() ZYc)_Og  
{ lHT?  
return sFilePath; li$(oA2  
} G'#a&6  
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public void setSFilePath(String value) =cX&H  
{ oju4.1  
sFilePath = value; P0 hC4Sxf  
} 7:9
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public String getSFileName() }+,1G!?z  
{ )LKutN?tBy  
return sFileName; Y{f;qbEQH'  
} s-3vp  
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public void setSFileName(String value) C[|jJ9VE,  
{ 6psK2d
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sFileName = value; }
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} [;83 IoU}  
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public int getNSplitter() cOxF.(L  
{ gR?=z}`@p  
return nSplitter; 305()  
} ja
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public void setNSplitter(int nCount) " q0lh  
{ j2k,)MHu!x  
nSplitter = nCount; ||0mfb  
} SB:-zQ5  
} kOs_]  
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/* bmGIxBRq  
**Utility.java o/)]z
 
*/ QZYD;&iY&  
package NetFox; ")i4w{_y  
.?@$Rd2@W  
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public class Utility { i%:oO KI  
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public Utility() )xoIH{
 
{ Kj
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} Nw/4z$].J  
=NQDxt}  
//线程睡眠 @9~6+BZOq  
public static void sleep(int nSecond) g-bHf]'  
{ F$^RM3  
try{  &)T5V  
Thread.sleep(nSecond); J)"2^?!&B  
} l*e*jA_>:7  
catch(Exception e) a[1^)=/DM  
{ 5.q2<a :  
e.printStackTrace (); |p-, B>p!  
} wJNiw)C  
} -2{NI.-Xd  
9!NL<}]{  
//日志 %7xx"$P:R  
public static void log(String sMsg) g~rZ=  
{ :54ik,l  
System.err.println(sMsg); 9l]+rs+  
} HcavA{H  
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public static void log(int sMsg) &'
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{ m6a`OkP  
System.err.println(sMsg); *GH`u*C_  
} f(6`5/C  
} w/IYQC\v  
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/* mCb(B48]%X  
**TestMethod.java %iPWg
  
*/ nQy.?*X  
package NetFox; idPx! fe  
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public class TestMethod { Ub2t7MU  
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public TestMethod() -GCC  
{ ///xx/weblogic60b2_win.exe MxQhkY-=  
try{ Ye% e!  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ikX"f?Q;S2  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); BiT #bg  
SiteFileFetch fileFetch = new SiteFileFetch(bean); @.0>gmY;:  
fileFetch.start(); 
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} Z-z^0QO  
catch(Exception e){e.printStackTrace ();} (~q.YJ'  
r'/&{?Je/  
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} YcOPqvQ  
O]3$$uI=QE  
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public static void main(String[] args) 6Ri+DPf:  
{ LM\H%=*L  
new TestMethod(); [ R  
} b 5<&hN4g  
} 8eq*q   
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