http断点续传简单实现（java)

/* /([kh~a  
**SiteFileFetch.java C1)!f j=  
*/ k4J+J.|  
package NetFox; r#a=@  
import java.io.*; oG\Vxg*  
import java.net.*; 6H$FhJF  
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public class SiteFileFetch extends Thread { q0vQa  
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SiteInfoBean siteInfoBean = null; //文件信息Bean u*`GiZAO  
long[] nStartPos; //开始位置 8lrpve  
long[] nEndPos; //结束位置 a`>B Ly5o  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 U
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long nFileLength; //文件长度 DvvK^+-~  
boolean bFirst = true; //是否第一次取文件 #\m<Sz5Gp#  
boolean bStop = false; //停止标志 onzxx4bax  
File tmpFile; //文件下载的临时信息 f+!(k)GWd  
DataOutputStream output; //输出到文件的输出流 wIt}dc  
Fx.=#bVX7  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） sO@Tf\d  
public SiteFileFetch(SiteInfoBean bean) throws IOException zrb}_  
{ B]tQ(s~  
siteInfoBean = bean; W'TZ%K) I  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); f-Z/tfC  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 26h21Z16q  
if(tmpFile.exists ()) t{{QE:/  
{ b\2 ds,  
bFirst = false; 5$k:t  
read_nPos(); [4f{w%~^  
} j\M?~=*w  
else @o`AmC. 8  
{ L!xi  
nStartPos = new long[bean.getNSplitter()]; '`Hr}  
nEndPos = new long[bean.getNSplitter()]; gcT%c|.  
} ?Ir:g=RP*  
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} 7%M_'P4 V  
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public void run() ~t~|"u"P  
{ ;2QP7PrSY  
//获得文件长度 T>W,'H  
//分割文件 ]Y&VT7+Z  
//实例FileSplitterFetch ;$g?T~v7  
//启动FileSplitterFetch线程 V'gh6`v  
//等待子线程返回 5{,<j\#L  
try{ 9pfIzs su3  
if(bFirst) 8quaXVj^a  
{ Z%UP6%  
nFileLength = getFileSize(); 'I;zJ`Trd  
if(nFileLength == -1) $XH^~i;  
{ OjA,]Gv6  
System.err.println("File Length is not known!"); ~k5W@`"W  
} Q3?F(ER@  
else if(nFileLength == -2) p]c%f2E>d  
{ Q"#J6@  
System.err.println("File is not access!"); fk-RV>yr  
} 4*;MJ[|  
else K|=A:  
{ I&5!=kR  
for(int i=0;i<nStartPos.length;i++) !&E-}}<  
{ W(p_.p"  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Ow,b^|  
} 8z\xrY  
for(int i=0;i<nEndPos.length-1;i++) ]Hv[IodJ  
{ #/37V2E  
nEndPos = nStartPos[i+1]; Fsg*FH7J  
} lyhiFkO iH  
nEndPos[nEndPos.length-1] = nFileLength; Wd ELV3  
} *LY8D<:zs  
} f|(M.U-  
6Kz,{F@  
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//启动子线程 \~wMfP8  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; d0> zS  
for(int i=0;i<nStartPos.length;i++) 9lE_nc  
{ >yDZ
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), />>\IR  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), _)-o1`*-  
nStartPos,nEndPos,i); \fe]c :  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); q5S9C%b  
fileSplitterFetch.start(); q@2siI~W  
} pfI&E#:5  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ?aMOZn?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 69.NPy@  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", TD_Oo-+\  
nEndPos = " + nFileLength); *Pg2c(Vg  
// fileSplitterFetch[nPos.length-1].start(); ySI!d|_  
g9F?z2^  
bg0

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//等待子线程结束 \l3h0R  
//int count = 0; m#p'iU*va,  
//是否结束while循环 T51 `oZ`  
boolean breakWhile = false; > Nr#O  
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while(!bStop) Oow2>F%
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{ BDVtSs<7  
write_nPos(); 8dhUBJ0_  
Utility.sleep(500); v &+R^iLE  
breakWhile = true; <a+Z;>  
QmIBaMI#  
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for(int i=0;i<nStartPos.length;i++) ? =+WRjF  
{ 9cm#56  
if(!fileSplitterFetch.bDownOver) {(}By/_  
{ Z/J y'$x  
breakWhile = false; #$y?v%^  
break; T[A69O]v  
} :~^(g$Z  
} L/^I*p,  
if(breakWhile) ?z u8)U  
break; ig &Y  
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//count++; PUX;I0Cf  
//if(count>4) Y nZiTe@  
// siteStop(); BsJC0I(  
} 4X|zmr:A  
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:\U{_@?`%  
System.err.println("文件下载结束！"); g=o4Q< #^y  
} po7qmLq  
catch(Exception e){e.printStackTrace ();} v*yuE5{  
} #3d(M  
7VI*N)OZ8  
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//获得文件长度 Rws3V"{`[  
public long getFileSize()
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{ *uvQ\.  
int nFileLength = -1; )
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try{ FC"8#*x  
URL url = new URL(siteInfoBean.getSSiteURL()); :eLVC7'  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wec)Ctj+  
httpConnection.setRequestProperty("User-Agent","NetFox"); lb1Xsgm{  
2f_:v6  
2GStN74Xr  
int responseCode=httpConnection.getResponseCode(); "C3/T&F  
if(responseCode>=400) Mb7I[
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{ >-{Hyx  
processErrorCode(responseCode); !0E&@X:-  
return -2; //-2 represent access is error WOf 4o  
} ]M
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String sHeader; ItTz.sQ  
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for(int i=1;;i++) $u6 3]rypm  
{ '[O;zJN;  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); h`.&f  
//Utility.log(in.readLine()); y18Y:)DkL  
sHeader=httpConnection.getHeaderFieldKey(i); &G$Ucc `  
if(sHeader!=null) KCDE{za  
{ P L+sR3bR  
if(sHeader.equals("Content-Length")) s&J]zb`  
{ XBw)H  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); kz7(Z'pw  
break; FNId;  
} *k>n<p3dd  
} pcI uN  
else Nl
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break; HLHz2-lI  
} F1Bq$*'N$w  
} :T(|&F[(  
catch(IOException e){e.printStackTrace ();} ?@ $r  
catch(Exception e){e.printStackTrace ();}
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Utility.log(nFileLength);  1ZB"EQ  
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return nFileLength; ^L&iR0  
} F^fdIZx  
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//保存下载信息（文件指针位置） njA#@fU  
private void write_nPos() {P#|zp4C{  
{ Hg (Gl  
try{ TrR8?-  
output = new DataOutputStream(new FileOutputStream(tmpFile)); _/<x  
output.writeInt(nStartPos.length); j^2j&Ta  
for(int i=0;i<nStartPos.length;i++) {+Cy U!O  
{ @49S`  
// output.writeLong(nPos); I[X772K  
output.writeLong(fileSplitterFetch.nStartPos); &~U ]~;@  
output.writeLong(fileSplitterFetch.nEndPos); r0 uwPf  
} NSA-
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output.close(); Tc3yS(aq  
} liz~7RY4  
catch(IOException e){e.printStackTrace ();} WvZ8/T'x  
catch(Exception e){e.printStackTrace ();} }|5Pr(I  
} c_!cv":s  
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gt w Q-  
//读取保存的下载信息（文件指针位置） )B8$<sv  
private void read_nPos() r^ ZEImjc  
{ D=
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try{ K8Y=S12Ti  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 4)o  
int nCount = input.readInt(); $
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nStartPos = new long[nCount]; @bP)406p  
nEndPos = new long[nCount]; i,9)\1R  
for(int i=0;i<nStartPos.length;i++) vd4ytC  
{ PXNh&N  
nStartPos = input.readLong(); )q3p-)@kQ  
nEndPos = input.readLong(); 6<(
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} fXQNHZ|4  
input.close(); i&G
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} X
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catch(IOException e){e.printStackTrace ();} zjoq6  
catch(Exception e){e.printStackTrace ();} e6RPIg  
} Qv/=&_6  
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private void processErrorCode(int nErrorCode) XACm[NY_  
{ [Hh9a;.*}h  
System.err.println("Error Code : " + nErrorCode); x0:m-C  
} e'b(gD}
 
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//停止文件下载 fIv*T[  
public void siteStop() -4_$lnw$  
{ L8#5*8W6  
bStop = true; (qulwOt~w  
for(int i=0;i<nStartPos.length;i++) @/-\k*T  
fileSplitterFetch.splitterStop(); G{%L
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} 7o5BXF  
} j]/RC(;?  
//负责部分文件的抓取 fMyti$1~  
**FileSplitterFetch.java
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*/ )~ h}  
package NetFox; e(=w(;84  
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import java.io.*; BbS
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import java.net.*; l3F6AlPql  
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public class FileSplitterFetch extends Thread { $43qME  
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String sURL; //File URL pgZXJ  
long nStartPos; //File Snippet Start Position Whf.fK  
long nEndPos; //File Snippet End Position `(/w y  
int nThreadID; //Thread's ID AoL2@C.C%D  
boolean bDownOver = false; //Downing is over :yjKL^G>  
boolean bStop = false; //Stop identical dQR-H7U  
FileAccessI fileAccessI = null; //File Access interface Qhcu>ra  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Lrq.Ab#  
{ m#Z# .j_2  
this.sURL = sURL; Is?La  
this.nStartPos = nStart; 9ahWIO%  
this.nEndPos = nEnd; j+v=Ul|l  
nThreadID = id; [!]2djc  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 L"*/:$EJL.  
} O~K>4ax  
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public void run() O2dW6bt  
{ ptxbDzOz  
while(nStartPos < nEndPos && !bStop) JKGe"  
{ Jd^,]  
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try{ KE3;V2Ym f  
URL url = new URL(sURL); eHNyNVz  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 0o*8#i/)!3  
httpConnection.setRequestProperty("User-Agent","NetFox"); 6-B|Y3)B  
String sProperty = "bytes="+nStartPos+"-"; ):_\;.L  
httpConnection.setRequestProperty("RANGE",sProperty); Ur=(.%@  
Utility.log(sProperty); R)ITy!z  
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!.(P~j][  
InputStream input = httpConnection.getInputStream(); T&o(N3lW  
//logResponseHead(httpConnection); VYImI>.t{  
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byte[] b = new byte[1024]; s?,Ek  
int nRead; Opc ZU{4b  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0eu$ W  
{ iaE^a^*
 
nStartPos += fileAccessI.write(b,0,nRead); H{?vbqQ  
//if(nThreadID == 1) "J8vjr1/  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 0Bi.6r  
}  e5*hE  
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Utility.log("Thread " + nThreadID + " is over!"); >!bJslWA  
bDownOver = true; FOy|F-j  
//nPos = fileAccessI.write (b,0,nRead); 8=uu8-l8g  
} x$Oq0d{
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catch(Exception e){e.printStackTrace ();} n!xt5=xP{  
} /Uy"M:|V1  
}
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//打印回应的头信息 OO*zhGD;[  
public void logResponseHead(HttpURLConnection con) -^h' >.  
{ fnX`Q[b4\A  
for(int i=1;;i++) 6'G6<8>-  
{ Jx](G>F4f1  
String header=con.getHeaderFieldKey(i); yS(fILV  
if(header!=null) 8sM|%<$=j  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); EL 8<U  
Utility.log(header+" : "+con.getHeaderField(header)); l@+7:n4K0  
else JJ2_hVU  
break; :hFIl0$,"3  
} 9s$CA4?HP  
} [b>Fn%y  
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public void splitterStop() T)TfB(  
{ 6BbGA*%{  
bStop = true; |G,tlchprs  
} "(z5{z
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} Et/\xL  
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/* :f}9
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**FileAccess.java ,<tX%n`v=  
*//文件访问(定位，写) >dG;w
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package NetFox; =Og)q$AL  
import java.io.*; %GA"GYL9'  
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public class FileAccessI implements Serializable{ 9- YwkK#z  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 B9$jSD  
RandomAccessFile oSavedFile; lpeEpI/gM  
long nPos; }v*G_}^  
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public FileAccessI() throws IOException ;/fF,L{c  
{ X>(TrdK_9"  
this("",0); ~yfNxH~k  
} ")dH,:#S  
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public FileAccessI(String sName,long nPos) throws IOException o+QE8H43  
{ MgOR2,cR  
oSavedFile = new RandomAccessFile(sName,"rw"); YY)s p%  
this.nPos = nPos; S=<}:#;u0  
oSavedFile.seek(nPos); 1#*a:F&re  
} M/ni6%x  
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 TYmP)  
public synchronized int write(byte[] b,int nStart,int nLen) %Yic
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{ CBOi`bEf  
int n = -1; ?_$=l1vf  
try{ y?m/*hh`  
oSavedFile.write(b,nStart,nLen); G_{&sa  
n = nLen; 6@e+C;j=  
} 8U>B~9:JO  
catch(IOException e) @}OL9Ch  
{ EB=-H#  
e.printStackTrace (); jN>{'TqW4  
} D@
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return n; fA<[f  
} (m.ob+D  
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} >.'*)@vQi  
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/* 8lb%eb]U  
**SiteInfoBean.java SAK!z!t  
*/ L%K\C  
package NetFox; c^u"I'#Q  
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public class SiteInfoBean { "@d[h,TM  
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private String sSiteURL; //Site's URL t!x5fNo)  
private String sFilePath; //Saved File's Path y[\VUzD*'  
private String sFileName; //Saved File's Name 6morum  
private int nSplitter; //Count of Splited Downloading File 2f:Eof(B  
}i`PGx
 
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public SiteInfoBean() SWQ5fcPu  
{//nSplitter的缺省值为5 tqeZ#w7  
//default value of nSplitter is 5 aj}sc/Qa  
this("","","",5); VUYmz)m5  
} n;U`m$vL%  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) <]4i`6{v  
{ ;F#7Px(q  
sSiteURL= sURL; ?)[EO(D  
sFilePath = sPath; D <&X_  
sFileName = sName; k
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this.nSplitter = nSpiltter; BV(8y.H  
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} y^Kph# F"  
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public String getSSiteURL() F;[T#N:~  
{ 7.@TK&  
return sSiteURL; %]6~Eq%s  
} ,^WJm?R  
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public void setSSiteURL(String value) 6{+{lBm=y  
{ \eb|eN0i  
sSiteURL = value; &q~:
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} P*@2.#oO  
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public String getSFilePath() -gas?^`  
{ .E&z$N  
return sFilePath; FwY&/\J7V  
} f<*Js)k  
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public void setSFilePath(String value) 0zCw>wBPW  
{ 3g~^[&
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sFilePath = value; wTGbd  
} ]f: v,a  
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public String getSFileName() {^rs#, W  
{ k`9)=&zX+  
return sFileName; `S.ZS}~!F  
} <[J[idY1he  
-

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public void setSFileName(String value) !>`N$-U X  
{ 7kK #\dI  
sFileName = value; ~+bGN  
} +:-57  
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public int getNSplitter() M- 2Tz[  
{ ls`,EFF  
return nSplitter; +|{RE.DL  
} f%)zg(YlO  
$GQ-(/  
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public void setNSplitter(int nCount) -:9P%jWt  
{ )VK }m9Ae  
nSplitter = nCount; Za7q$7F7Bc  
} P^Q[-e{  
} 6^n0[7  
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/* OxtOd\0$  
**Utility.java l|+BC  
*/ ?D)<,  
package NetFox; TLf9>= OVh  
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public class Utility { pdb1GDl0q  
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public Utility() m8JR@!t7  
{ Ty@=yA17  
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} \[>9UC%  
%|l8f>3[  
//线程睡眠 %q322->
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public static void sleep(int nSecond) hv$m4,0WB  
{ f8<o8*`7  
try{ R%H$%cnj  
Thread.sleep(nSecond); b7\ cxgRq  
} \zkw2*t  
catch(Exception e) $hVYTy~}  
{ ]PP:oriWl  
e.printStackTrace (); 4YMX|1wd)  
} )Vk6;__  
} ";w}3+R  
#W2[  
//日志 |nk3^
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public static void log(String sMsg) l\!-2 T6Y  
{ ]G}B 0u3  
System.err.println(sMsg); 's!-80sd  
} ExXM:1 e26  
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R
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public static void log(int sMsg) :9Y$'+ <&H  
{ %_aMl  
System.err.println(sMsg); @C-dG7U.P  
} R,!Q Zxmg  
} daAyx-  
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/* JH]K/sC>  
**TestMethod.java
|m?vVLq  
*/ 2~p[7?sp'  
package NetFox; 5NXt$k5  
OAZ#|U   
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public class TestMethod { &MgeYpd  
- ?!:{UXl  
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public TestMethod() 6ZqgY1  
{ ///xx/weblogic60b2_win.exe 0gF!!m  
try{ cM&'[CI  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); HT_TP q  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Y/8K;U|  
SiteFileFetch fileFetch = new SiteFileFetch(bean); [$(R#tZ+  
fileFetch.start(); cQZ652F9  
} |\uYv|sT  
catch(Exception e){e.printStackTrace ();} bv d
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} Px'!;  
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} i)$n(A)K  
public static void main(String[] args) gglQU"=g{  
{ dj[apuiF  
new TestMethod(); 4*UP.r@  
} :PnSQjV:  
} 8C.!V =@\  
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