http断点续传简单实现（java)

/* GP,<`l&  
**SiteFileFetch.java ;YH[G;aJ  
*/ %SA!p;  
package NetFox; ' Q7Y-V  
import java.io.*; 8Y{s;U0n  
import java.net.*; kiUk4&1  
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public class SiteFileFetch extends Thread { J;QUPpHZ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean c:\shAM&  
long[] nStartPos; //开始位置 T|){<  
long[] nEndPos; //结束位置 6X_\Ve  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 PHra+NY#A  
long nFileLength; //文件长度 AEg(m<t  
boolean bFirst = true; //是否第一次取文件 S
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boolean bStop = false; //停止标志 63&^BW  
File tmpFile; //文件下载的临时信息 HlB]38  
DataOutputStream output; //输出到文件的输出流 MXZ>"G  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） B3 zk(RNZ  
public SiteFileFetch(SiteInfoBean bean) throws IOException <~"lie1  
{ Poy^RpnX  
siteInfoBean = bean; YT-=;uK^S  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); #&Is GyU  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Hf
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if(tmpFile.exists ()) X?Pl<l&  
{ 9F##F-
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bFirst = false; 46x.i;b7  
read_nPos(); U ?b".hJ2  
} (q;bg1\UK  
else ;hDa@3|]34  
{ <+U|dX  
nStartPos = new long[bean.getNSplitter()]; _D;@v?n6!O  
nEndPos = new long[bean.getNSplitter()]; *@S@x{{s  
} ^vni&sJ  
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} +t!S'|C  
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public void run() 1~yZ T  
{ #1/}3+=5B  
//获得文件长度 gNj7@bX~  
//分割文件 SNY (*  
//实例FileSplitterFetch "v]%3i.* -  
//启动FileSplitterFetch线程 D$r Uid  
//等待子线程返回 ZI13  
try{ VLvS$0(}Z  
if(bFirst) \
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{ >lzA]aM$c  
nFileLength = getFileSize(); +RDJY(Y$  
if(nFileLength == -1) :0~QRc-u  
{ \;9W.d1i
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System.err.println("File Length is not known!"); u=NG6
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} UT]?;o"  
else if(nFileLength == -2) -4 Ux,9
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{ "Ij
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System.err.println("File is not access!"); AHbZQulC  
} r@}bDkx  
else xyeA2Y  
{ >hsuAU.UOR  
for(int i=0;i<nStartPos.length;i++) [~mGsXV  
{ =JO^XwUOo  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Paf%rv2  
} +]wuJSxc  
for(int i=0;i<nEndPos.length-1;i++) q9*MNHg}  
{ <M+R\SH-  
nEndPos = nStartPos[i+1]; CboLH0Fa  
} v;2CU  
nEndPos[nEndPos.length-1] = nFileLength; )b4$A:  
} grom\  
} p9[6^rjx8  
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//启动子线程 .qD@ Y3-  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; p3x?[Ww  
for(int i=0;i<nStartPos.length;i++) yi6N-7  
{ O<*5$,K9  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), %V_-%/3Z  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), /n5n )P@L  
nStartPos,nEndPos,i); ZCui Fm  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); DDd/DAkCX  
fileSplitterFetch.start(); })F*:9i*  
} 1=VJ&D;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6^F'|Wh  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1);
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 1%
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nEndPos = " + nFileLength); '+y_\  
// fileSplitterFetch[nPos.length-1].start(); wa09$
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//等待子线程结束 msx-O=4g  
//int count = 0; +Ic ~ f1zh  
//是否结束while循环 k5BXirB  
boolean breakWhile = false; 2.I^Xf2  
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while(!bStop) PX O
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{ >t+ qe/  
write_nPos(); S;\R!%t_  
Utility.sleep(500); @tT-JwU  
breakWhile = true; <^R{U&Z@  
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for(int i=0;i<nStartPos.length;i++) ^4Uw8-/9  
{ |`O5Xs1{B  
if(!fileSplitterFetch.bDownOver) .TB"eUy  
{ \_]En43mg  
breakWhile = false; H=c`&N7E  
break; L=!of{4Z(}  
} NTs7KSgZ  
} vp)Vb^K>  
if(breakWhile) v4vf}.L]  
break; p.JXSn  
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//count++; sH#X0fG  
//if(count>4) _=f=fcl  
// siteStop(); :3ZYJW1  
} b'p4wE>  
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System.err.println("文件下载结束！"); #CUzuk&  
} o+O}Te  
catch(Exception e){e.printStackTrace ();} [:;# ]?  
} n%%7KTqu  
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//获得文件长度 hlJpElYf  
public long getFileSize() IzLF'F  
{ -6~'cm  
int nFileLength = -1; v1G"3fy
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try{ $9!D\N,}]C  
URL url = new URL(siteInfoBean.getSSiteURL()); R=)55qu  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); f>9s!Hpu_  
httpConnection.setRequestProperty("User-Agent","NetFox"); ??qq:`s  
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int responseCode=httpConnection.getResponseCode(); a>m
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if(responseCode>=400) @\P4/+"9  
{ *<4Em{rZ5  
processErrorCode(responseCode); q?j|K|%   
return -2; //-2 represent access is error `{K_/Cit  
} oDB`iiBXQ  
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77 r(*.O|  
String sHeader; vG.9H_&  
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for(int i=1;;i++) .10y0FL4  
{ h:bru:ef  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); L{{CAB!  
//Utility.log(in.readLine()); O~Wt600{E  
sHeader=httpConnection.getHeaderFieldKey(i); s Kicn5  
if(sHeader!=null) T Eu'*>g  
{ /1w2ehE<  
if(sHeader.equals("Content-Length")) V\5 L?}  
{ 1QqHF$S  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); cW8
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break; ,Ds.x@p  
} Z=S>0|`R  
} ;az5ZsvN D  
else bJ /5|E?  
break; _D7]-3uC!  
} m#e3%150{  
} ^]C&tG0 !  
catch(IOException e){e.printStackTrace ();} |`d0^(X  
catch(Exception e){e.printStackTrace ();} xJ8%<RR!t  
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Utility.log(nFileLength); *>8ce-PV  
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return nFileLength; RIn9(r  
} FqFapRX66Z  
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//保存下载信息（文件指针位置） |J5
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private void write_nPos() 9O*_L:4o  
{ 8|?LN8rp  
try{ &^&zR(o`  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ; 0v>Rfa  
output.writeInt(nStartPos.length); m} ?r
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for(int i=0;i<nStartPos.length;i++) fnKY1y]2+  
{ =3~/:8o  
// output.writeLong(nPos); u+t$l^S  
output.writeLong(fileSplitterFetch.nStartPos); {LzH&qu  
output.writeLong(fileSplitterFetch.nEndPos); Z)9g~g94  
} {XurC}#\  
output.close(); BP[|nL  
} ^ZD
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catch(IOException e){e.printStackTrace ();} w~R`D  
catch(Exception e){e.printStackTrace ();} 07g':QU@
 
} [4&
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//读取保存的下载信息（文件指针位置） qml2XJ>  
private void read_nPos() BQ</g* $;  
{ `/&SxQB<  
try{ Z;Rp+X  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); pv!oz2w1  
int nCount = input.readInt(); [%A4]QzWh  
nStartPos = new long[nCount]; `Pn[tuIO  
nEndPos = new long[nCount]; U:6W+p8  
for(int i=0;i<nStartPos.length;i++) 3voT^o  
{ d&8APe  
nStartPos = input.readLong(); tMx}*l|]  
nEndPos = input.readLong(); QYb33pN|  
} V&]DzjT/  
input.close(); |!SOG  
} I&|f'pn^<  
catch(IOException e){e.printStackTrace ();} )D-c]+yt  
catch(Exception e){e.printStackTrace ();}  _?voU  
} <|Yj%f  
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private void processErrorCode(int nErrorCode) LK9g0_  
{ $4FX(O0Q@  
System.err.println("Error Code : " + nErrorCode); s?Uh|BfB  
} Z
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2?C`4AR[2H  
//停止文件下载 =,!\~`^  
public void siteStop() ?YM4b5!3T  
{ /Ss7"*JLe  
bStop = true; d@0Kr5_  
for(int i=0;i<nStartPos.length;i++) b IW'c_ ,  
fileSplitterFetch.splitterStop(); DciwQcG  
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} #3=P4FUz.  
} ?Ucu#UO
 
//负责部分文件的抓取 sd#|3  
**FileSplitterFetch.java 3ss6_xd+  
*/ }ov&.,vQ  
package NetFox; Dq@2-Cv  
Z BUArIC  
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import java.io.*; &5{xXWJK  
import java.net.*; -tsDMji~V  
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public class FileSplitterFetch extends Thread { 6pOx'u>h+  
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String sURL; //File URL Syp"L;H8Em  
long nStartPos; //File Snippet Start Position 88"Sai  
long nEndPos; //File Snippet End Position 3=Ec"  
int nThreadID; //Thread's ID <mMTD8Sx]  
boolean bDownOver = false; //Downing is over P|2E2=G  
boolean bStop = false; //Stop identical `cQo0{xK  
FileAccessI fileAccessI = null; //File Access interface F 09DV<j  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ZR v"h/~  
{ + 1IQYa|  
this.sURL = sURL; /"H`.LD.?  
this.nStartPos = nStart; w=h1pwY  
this.nEndPos = nEnd; p Rdk>Ph  
nThreadID = id; 7?gFy-  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 3cS2gxF  
} *=ZsqOHwG  
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public void run() qjAWeS/  
{ b*fgv9Kh'  
while(nStartPos < nEndPos && !bStop) [+*$\  
{ /WV7gO&L1  
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try{ R.[Z]-X  
URL url = new URL(sURL); _{vkX<s  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); j6~nE'sQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); X7UuwIIP  
String sProperty = "bytes="+nStartPos+"-"; qzw'zV  
httpConnection.setRequestProperty("RANGE",sProperty); iGDLZE+
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Utility.log(sProperty); cH-@V<  
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}  
InputStream input = httpConnection.getInputStream(); G'zF)0oD  
//logResponseHead(httpConnection); ;VO.!5W@eg  
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byte[] b = new byte[1024]; )4?x5#  
int nRead; Ed0IWPx  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 9jp:k><\(c  
{ @\oz4^  
nStartPos += fileAccessI.write(b,0,nRead); v]%WH~>  
//if(nThreadID == 1) *?+V65~dW  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Giq=*D+  
} B()/.w?A  
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Utility.log("Thread " + nThreadID + " is over!"); i`/+,<  
bDownOver = true; b5m=7;u*h  
//nPos = fileAccessI.write (b,0,nRead); MC0TaP  
} #zrTY9m7  
catch(Exception e){e.printStackTrace ();} m|=Ecu  
} cw&Hgjj2  
} .*$
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; UiwH  
//打印回应的头信息 MRr</o  
public void logResponseHead(HttpURLConnection con) \ 6EKgC1  
{ !/ y!QXj  
for(int i=1;;i++) @`-[;?>  
{ {:c]|^w6  
String header=con.getHeaderFieldKey(i); M L7\BT  
if(header!=null) /!}'t  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ODc9r }
 
Utility.log(header+" : "+con.getHeaderField(header)); ;o/>JHGj  
else Hv]7e|  
break; E@a3~a  
} _8}QlT  
} zJ+8FWy:S  
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public void splitterStop() SxyONp.$\  
{ w|mb4AyL{?  
bStop = true; 
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} :RSz4   

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} zPEg  
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/* y5= `ap  
**FileAccess.java RWgDD;&_[a  
*//文件访问(定位，写) *xf._~E  
package NetFox; 6b8;}],|  
import java.io.*; EzW)'Zzw~  
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public class FileAccessI implements Serializable{ t3Z_Dp~\  
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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 UV}73Sp  
RandomAccessFile oSavedFile; 9/SXs0  
long nPos; ej&<GM|  
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public FileAccessI() throws IOException >Sa*`q3J  
{ Z') pf  
this("",0); :"6q,W  
} Nf+b"&Zh`  
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public FileAccessI(String sName,long nPos) throws IOException f:zFFpP.j@  
{ ,3v+PIcMM+  
oSavedFile = new RandomAccessFile(sName,"rw"); s#h8%['  
this.nPos = nPos; Q|}aR:4  
oSavedFile.seek(nPos); 0Q"u#V Sp  
} @L84>3O  
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public synchronized int write(byte[] b,int nStart,int nLen) N-lGa@ j  
{ 6*9}4`  
int n = -1; h:XzUxL\  
try{ 8,?v?uE  
oSavedFile.write(b,nStart,nLen); -3Avs9`5  
n = nLen; [LT^sb  
} SgMrce<;  
catch(IOException e) HQ9f,<  
{ F Kc;W  
e.printStackTrace (); E}CiQUx  
} R cY>k  
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return n; @vgG1w  
} 3>
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} 8pM>Co!  
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ZA~Z1Mro#"  
/* v,NHQyk  
**SiteInfoBean.java 7Y=cn_ wU  
*/ d {lP  
package NetFox; ?:^mBb)T  
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public class SiteInfoBean { C7T(+Wd!,  
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private String sSiteURL; //Site's URL fBBa4"OK=  
private String sFilePath; //Saved File's Path 8$xPex~2  
private String sFileName; //Saved File's Name l>lW]W  
private int nSplitter; //Count of Splited Downloading File ]!1OH |Ad  
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public SiteInfoBean() Mr+@
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{//nSplitter的缺省值为5 < V\Y@Ei+  
//default value of nSplitter is 5 7RU}FE  
this("","","",5); ~:;3uLs,8  
} 5OM?3M  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) q^8EOAvnZ  
{ k1z$e*u&r  
sSiteURL= sURL; $ E1Tb{'  
sFilePath = sPath; )j6eE+gF  
sFileName = sName; Q^}%c U0  
this.nSplitter = nSpiltter; ?<X(]I.j  
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} u]C`6)>  
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public String getSSiteURL() i< (s}wg  
{ QrD o|GtE  
return sSiteURL; t$&Qv)  
} ,lYaA5&I  
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public void setSSiteURL(String value) OQ/<-+<
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{ ^jdL@#k00  
sSiteURL = value; |
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} ~KjJ\b)R  
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public String getSFilePath() HCA{pR`  
{ -ML6d&cm  
return sFilePath; B,$l4m4  
}
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public void setSFilePath(String value) ]*"s\ix  
{ XY7Qa!>7j  
sFilePath = value; Ar9nBJ`  
} /k\01hc`  
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public String getSFileName() R5Yl1   
{ /z."
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return sFileName; 7D"%%|: h  
} ul7o%Hs  
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r >{G`de4  
public void setSFileName(String value) :LJ7ru2  
{ :bM+&EP  
sFileName = value; `linG1mF  
} 8"'x)y  
'3tw<k!1{.  
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public int getNSplitter() ;uI~BV*3  
{ /4S;QEv  
return nSplitter; 4 (?MUc  
} E,G<_40  
;#?M)o:q  
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public void setNSplitter(int nCount) IxSV?k   
{ >X}{BDMb.  
nSplitter = nCount; u/^|XOy  
} )-P!Ae_.v  
} #5CI)4x0!  
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7 &)]) {Q  
/* R zR?&J  
**Utility.java +`en{$%%  
*/ wJ"ev.A)  
package NetFox; }Ag|gF!_  
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public class Utility { R|,7d:k  
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X
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public Utility() N{akg90  
{ HQVh+(  
0A$SYF$O+[  
oN2=DYC41  
} iSp  
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//线程睡眠 8:;#,Urr  
public static void sleep(int nSecond) D!> d0k,Y  
{ e$l6gY  
try{ LVtu*k   
Thread.sleep(nSecond); 9/TY\?U  
} a<Uqyilm  
catch(Exception e) 9w^zY;Y  
{ - V) R<  
e.printStackTrace (); 3P=w =~e  
} z_SagU,\  
} <&#+E%E4  
-e`;bX_N)  
//日志 `7Ug/R<  
public static void log(String sMsg) 1$LIpx  
{ tm)*2lH6  
System.err.println(sMsg); ~t/JCxa  
} Hhv$4;&X  
q^Tis>*u6  
-WR}m6yMr  
public static void log(int sMsg) NrJzVGeS  
{ iyM^[/-R6  
System.err.println(sMsg); /A(NuB<Pq  
} UVX"fZ)  
} IsYP0(L  
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/* (!zM\sF  
**TestMethod.java Z!\@%`0$  
*/ xfHyC'?  
package NetFox; !Tfij(91  
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br,  
public class TestMethod { 2w1tK  
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public TestMethod() R{3CW^1
  
{ ///xx/weblogic60b2_win.exe bEpMaBN  
try{ J/Q|uRpmqr  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); j7/(sf  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); X%4h(7;v  
SiteFileFetch fileFetch = new SiteFileFetch(bean); !Yh}H<w0  
fileFetch.start(); pCt}66k}  
} Fj=NiZ=  
catch(Exception e){e.printStackTrace ();} 
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} tV`&-
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public static void main(String[] args) ,IjdO(?TC  
{ o/JPYBhdl  
new TestMethod(); g_ M-F  
} 6E+=Xi  
} &BgU:R,  
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