http断点续传简单实现（java)

/* 
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**SiteFileFetch.java U$=Z`^<  
*/ F)aF.'$-/  
package NetFox; R-k
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import java.io.*; vgn,ZcX  
import java.net.*; x9]vhR/av  
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public class SiteFileFetch extends Thread { ?5[$d{ Gjl  
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SiteInfoBean siteInfoBean = null; //文件信息Bean H-% B<7  
long[] nStartPos; //开始位置 WxJaE;`Ige  
long[] nEndPos; //结束位置 L'e|D=y  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Nah\4-75&  
long nFileLength; //文件长度 8yswi[  
boolean bFirst = true; //是否第一次取文件 hBDmC_\~  
boolean bStop = false; //停止标志 !%D;H~mQ  
File tmpFile; //文件下载的临时信息 $m-@ICG#  
DataOutputStream output; //输出到文件的输出流 fndH]Yp  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） \Jwc[R&x  
public SiteFileFetch(SiteInfoBean bean) throws IOException Co/04F.  
{ TD/ 4lL~(x  
siteInfoBean = bean; [.;I}  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); #8WHIDS>  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 2p*!up(  
if(tmpFile.exists ()) B;<zA' 1  
{ tt&{f <*  
bFirst = false; /W{^hVkvC  
read_nPos(); w,1*dn  
} XCGK&OGI  
else ~'Korxa  
{ US<l4  
nStartPos = new long[bean.getNSplitter()]; r+a0.  
nEndPos = new long[bean.getNSplitter()]; @><8YN^)%  
} 7Xh ;dJAF3  
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} ] `;Fc8$  
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public void run() [1e/@eC5  
{ 5hDm[*
83  
//获得文件长度 bW
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//分割文件 Rf!$n7& \  
//实例FileSplitterFetch  ,}^FV~  
//启动FileSplitterFetch线程 Rz<'&Z>;  
//等待子线程返回 "!#KQ''R  
try{ H96|{q=  
if(bFirst) Jb|dpu/e  
{ k7nke^,|  
nFileLength = getFileSize(); ?{1& J9H  
if(nFileLength == -1) $L72%T  
{ C5TC@w1*  
System.err.println("File Length is not known!"); LP>GM=S#"  
} dp }zG+  
else if(nFileLength == -2) 7\i> >  
{ DNRWE1P2bg  
System.err.println("File is not access!"); o}L\b,])  
} 7! /+[G  
else {afIr1j/m  
{ %/r:iD  
for(int i=0;i<nStartPos.length;i++) wYd{X 8
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{ v
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); riSgb=7q9  
} xQxq33\  
for(int i=0;i<nEndPos.length-1;i++) mfk^t`w_  
{ .6pVt_f0/  
nEndPos = nStartPos[i+1]; V+$fh2t  
} ._6Q "JAB  
nEndPos[nEndPos.length-1] = nFileLength; S0lt_~  
} XrGP]k6.^  
} % 3<7HY]~  
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,a":/ /[  
//启动子线程 @h%Nn)QBq  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; V?n=yg  
for(int i=0;i<nStartPos.length;i++) 7J|nqr`>t  
{ ]
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Ime"}*9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), PebyH"M(  
nStartPos,nEndPos,i); ~Vf A  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); wu0q.]  
fileSplitterFetch.start(); rouaT  
} p<\7" SB=  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,HK-mAH   
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); !{b4+!@p  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", G^le91$  
nEndPos = " + nFileLength); G54`{V4&s  
// fileSplitterFetch[nPos.length-1].start(); ^(Wu$\SA  
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//等待子线程结束 8Q73h/3  
//int count = 0; kK.[v'[>&  
//是否结束while循环
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boolean breakWhile = false; 3qy4nPg  
sV]I]DR  
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while(!bStop) ZQ_AqzT3D  
{ mpd?F'V  
write_nPos(); /1b7f'  
Utility.sleep(500); /sdZf
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breakWhile = true; sE[ Yg8yAt  
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for(int i=0;i<nStartPos.length;i++) @jKB[S;JSn  
{ &W*^&0AV  
if(!fileSplitterFetch.bDownOver) nNh5f]]  
{ @el  
breakWhile = false; pz]!T'  
break; EvF[h:C2  
} k\-h-0[|  
} kG`&Z9P  
if(breakWhile) L.:8qY  
break; _P*QX  
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wJh/tb=$o  
//count++; #g<6ISuf  
//if(count>4) k&17 (Tv$  
// siteStop(); P[tYu:  
} TrBW0Bn>p  
U|x#'jGo'  

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System.err.println("文件下载结束！"); @]Lu"h#u=  
} LX#gc.c  
catch(Exception e){e.printStackTrace ();} 8k;il54#  
} #gXxBM  
iWIq~t*,H]  
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//获得文件长度 7 4]qz,  
public long getFileSize() s%1ZraMvJ  
{ *NC@o*  
int nFileLength = -1; #@F.wV0  
try{ &_74h);2I:  
URL url = new URL(siteInfoBean.getSSiteURL()); ~yJJ00%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); w@LLxL>Y  
httpConnection.setRequestProperty("User-Agent","NetFox"); Gr#WD=I-}  
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int responseCode=httpConnection.getResponseCode(); e0hY   
if(responseCode>=400) w1eFm:'  
{
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processErrorCode(responseCode); ~ 7<M6F  
return -2; //-2 represent access is error I+ Y{_yw"f  
} BAtjYPX'w  
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String sHeader; /*MioaQB}p  
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for(int i=1;;i++) t(jE9t|2e6  
{ w"C,oo3  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); M{4XNE]m  
//Utility.log(in.readLine()); l z-I[*bA  
sHeader=httpConnection.getHeaderFieldKey(i); }
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'  
if(sHeader!=null) O&,8X-Ix  
{ JfmYr47Pv  
if(sHeader.equals("Content-Length")) W2'!Pc,W  
{ Fm*npK
 
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); QNH3\<IS  
break; c=X+uO-  
} <~uzKs0  
} Q!_d6-*u  
else (>NZYPw^3  
break; aemi;61T\  
} +}PN+:yV  
} Je}0KW3G9L  
catch(IOException e){e.printStackTrace ();} +wxsAGy_j  
catch(Exception e){e.printStackTrace ();} m.<u!MI  
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Utility.log(nFileLength); 
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return nFileLength; {`,)<R>}  
} dqs~K7O^E  
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2=/-,kOL_  
//保存下载信息（文件指针位置）
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private void write_nPos() Qj*.Z4ue  
{ xF@&wg  
try{ jFUpf.v2  
output = new DataOutputStream(new FileOutputStream(tmpFile)); MpBdke$  
output.writeInt(nStartPos.length); FRQ0t!b<M1  
for(int i=0;i<nStartPos.length;i++) K6sXw[VC[  
{ w)`XM  
// output.writeLong(nPos); @\o"
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output.writeLong(fileSplitterFetch.nStartPos); I2Imb9k~B  
output.writeLong(fileSplitterFetch.nEndPos); iaLZ|\`3a  
} PjH'5Y  
output.close(); Wky9wr:g  
} -$DfnAh  
catch(IOException e){e.printStackTrace ();} v; R2,`[W  
catch(Exception e){e.printStackTrace ();} 6)7cw8^  
} Fk^N7EJ:$  
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//读取保存的下载信息（文件指针位置）
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private void read_nPos() 6uT*Fg-G  
{ *mbzK*  
try{ 8QZI(Xe9r  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); >0W P:-\*  
int nCount = input.readInt(); %qiVbm0  
nStartPos = new long[nCount]; +vaA P=  
nEndPos = new long[nCount]; Ikw@B)0}  
for(int i=0;i<nStartPos.length;i++) t%%()!|)j  
{ Q;g7<w17  
nStartPos = input.readLong(); IWq#W(yM  
nEndPos = input.readLong();
&N._}ts  
} JWIY0iP  
input.close(); _OyQ:>M6P  
} 0Q`v#$?":  
catch(IOException e){e.printStackTrace ();} E6ZkO/  
catch(Exception e){e.printStackTrace ();} \2e^
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} `$S&:Q,  
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private void processErrorCode(int nErrorCode) %1.F;-GdsW  
{ YO$D-  
System.err.println("Error Code : " + nErrorCode); f&mi nBU  
} 1P*hC<  
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//停止文件下载 bWAa: r  
public void siteStop() q\]X1N  
{ }cr'o"4  
bStop = true; YrB-n  
for(int i=0;i<nStartPos.length;i++) ^9:`D@Z+  
fileSplitterFetch.splitterStop(); V5z2.} 'o-  
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} yV )fJ_  
} 0hV#]`9`gN  
//负责部分文件的抓取 {;u,04OVK  
**FileSplitterFetch.java Z$JJ0X  
*/ UZ2_FP  
package NetFox; YLGE{bS  
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import java.io.*; X<$Tn60,  
import java.net.*; @,TIw[p  
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public class FileSplitterFetch extends Thread { 4,z|hY_*t  
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String sURL; //File URL N=KtW?C  
long nStartPos; //File Snippet Start Position A5TSbW']+5  
long nEndPos; //File Snippet End Position abQ.N  
int nThreadID; //Thread's ID {tUe(  
boolean bDownOver = false; //Downing is over TZ5TkE;1  
boolean bStop = false; //Stop identical $R/@8qnP W  
FileAccessI fileAccessI = null; //File Access interface _&BK4?H@b  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 5@m ,*n&[  
{ ]690ey$E:j  
this.sURL = sURL; (.cA'f?h  
this.nStartPos = nStart; HS/.H,X  
this.nEndPos = nEnd; .Y;
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nThreadID = id; _ZK^JS  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 N*}soMPV^.  
} JM|HnyI  
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public void run() QQ.?A(U7  
{ \+%~7Bi]z  
while(nStartPos < nEndPos && !bStop) ~p?A
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{ Wvf>5g)?  
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try{ 5 ix*wu`,  
URL url = new URL(sURL); !q\=e@j-i  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); S F*C'  
httpConnection.setRequestProperty("User-Agent","NetFox"); <v|"eq}  
String sProperty = "bytes="+nStartPos+"-"; ,bl }@0A  
httpConnection.setRequestProperty("RANGE",sProperty); ]yf?i350  
Utility.log(sProperty); ^EX"fRwNi  
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InputStream input = httpConnection.getInputStream(); wWb>V&3  
//logResponseHead(httpConnection); /B@{w-N  
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byte[] b = new byte[1024]; TjTG+uQ  
int nRead; $:F+Nf 8  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Y0a[Lb0  
{ QPDh!A3T  
nStartPos += fileAccessI.write(b,0,nRead); W/!P1M n  
//if(nThreadID == 1) #XDgvX >  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); d^aVP  
} 4@  
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Utility.log("Thread " + nThreadID + " is over!"); "=Br&FN{|  
bDownOver = true; smf"F\Ws  
//nPos = fileAccessI.write (b,0,nRead); qgrJi +WZ  
} U|} ?{x  
catch(Exception e){e.printStackTrace ();} VV$t*9w  
} ,
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} {JgY-#R?{(  
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//打印回应的头信息 xak)YOLRV  
public void logResponseHead(HttpURLConnection con) }L_YpG7  
{ Lb/GL\J)  
for(int i=1;;i++) p@Y=6Bw  
{ t@qf/1  
String header=con.getHeaderFieldKey(i); 9=>f
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if(header!=null) eO!9;dJ  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 1#A$&'&\J;  
Utility.log(header+" : "+con.getHeaderField(header)); 53])@Mmus  
else 7=CkZ&(?  
break; pmNy=ZXx  
} 0kkDlWkzo  
} =8\.fp  
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public void splitterStop() ,dIev<  
{ xqG<R5k>>  
bStop = true; bE_8NA"2  
} qiNVaV\wr|  
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:  
} Al-`}g+^  
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/* MET9rT  
**FileAccess.java YMX9Z||  
*//文件访问(定位，写) e}UQN:1  
package NetFox; RuPnWx!  
import java.io.*; .Kb3VNgwvm  
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public class FileAccessI implements Serializable{ [8iY0m_Qe  
#CC5+  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 jc5[r;#  
RandomAccessFile oSavedFile; "?8)}
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long nPos; |?!i},Ki;  
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public FileAccessI() throws IOException IO\4dU)  
{ '$9o(m#  
this("",0); !zA@{gvEc  
} oW3"J6,S  
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#  
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public FileAccessI(String sName,long nPos) throws IOException o`bc/3!  
{ 2d&F<J<sU  
oSavedFile = new RandomAccessFile(sName,"rw"); ;k<dp7^  
this.nPos = nPos; <Riz!(G  
oSavedFile.seek(nPos); 'R7 \  
} -> cL)  
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){;XI2
 
public synchronized int write(byte[] b,int nStart,int nLen) QZzamT)"  
{ _ \D%  
int n = -1; w*qj0:i5as  
try{ ]S6Gz/4aV+  
oSavedFile.write(b,nStart,nLen); GKBoSSnV&  
n = nLen; =Hi@q "  
} ^hIdmTf6  
catch(IOException e) Z8|<%1Kge  
{ /(dP)ysc  
e.printStackTrace (); |mEWN/@C  
} ,Bk5(e  
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return n; #Bd]M#J17a  
} bZnOX*y]  
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} >e;-$$e  
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/* >US*7m }  
**SiteInfoBean.java $Z]&3VxxY  
*/ "=h1gql'  
package NetFox; xcB\Y:   
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public class SiteInfoBean { hG1:E:}  
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private String sSiteURL; //Site's URL GY~$<^AK  
private String sFilePath; //Saved File's Path zx.
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private String sFileName; //Saved File's Name c!6D{(sfh  
private int nSplitter; //Count of Splited Downloading File Itl8#LpLM  
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f"MID6  
public SiteInfoBean() +:MSY p  
{//nSplitter的缺省值为5 @Cj!MZ=T  
//default value of nSplitter is 5 $RD~,<oEm  
this("","","",5); 3lP;=*m.  
} 'a~@q~!  
~ ld.I4  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) f}:C~L!  
{ >xFvfuy
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sSiteURL= sURL; 1NZ"\9=U  
sFilePath = sPath; F y+NJSG  
sFileName = sName; z0 "DbZ;d  
this.nSplitter = nSpiltter; _7Y h[I4  
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} 6h:QSVfx  
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public String getSSiteURL() =2R4Z8
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{ ":
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return sSiteURL; ^m\o(R  
} Kd\0nf6  
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public void setSSiteURL(String value) vrs  
{ v:O{"s  
sSiteURL = value; '/\  
} `+H=3`}
X  
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public String getSFilePath() bvox7V>  
{ FYAEM!dyy  
return sFilePath; &^=Lr:I  
} s QDgNJbU  
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public void setSFilePath(String value) 5y#,z`S  
{ 77RZ<u9/`  
sFilePath = value; wh:;G`6S  
} .LzA'q1+z  
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public String getSFileName() [,=?e  
{ }M07-qIX{  
return sFileName; d4Uw+3ikW  
} *!5CL'  
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public void setSFileName(String value) vhe Y F@  
{ 
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sFileName = value; +=tdgw/  
} Wf~^,]9N  
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public int getNSplitter() 66=[6U9 *  
{ %4~"$kE  
return nSplitter; 4^7 v@3  
} o}N@Q-i gq  
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public void setNSplitter(int nCount) LjZlKB5C  
{ EP>u%]#  
nSplitter = nCount; t{k:H4  
} !I7$e&Uz@  
} ff--y8h  
iI GK"}  
*|rdR2R!  
/* F^dJ{<yX  
**Utility.java 2Bcc
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*/ WK%cbFq(  
package NetFox; XYcZ;Z9:  
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public class Utility { ;lMvxt:  
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public Utility() {gD ED  
{ ieyK$q  
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} L>Y+}]~  
C[FHqo9M?H  
//线程睡眠 PT>b%7Of  
public static void sleep(int nSecond) @A[)\E1  
{ %. 1/#{  
try{ v
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Thread.sleep(nSecond); oW~W(h!  
} Zkp~qx  
catch(Exception e) F^l1WX6  
{ W8W7<ml0A  
e.printStackTrace (); >a"J);p  
} ()lgd7|+  
} EjP;P}_iK  
rS@/@jKZE  
//日志 [6VB&   
public static void log(String sMsg) Z`TfS+O6  
{ 1/$PxQ  
System.err.println(sMsg); MlV(XG>'  
} ! ._q8q\  
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!  
#:6-O  
public static void log(int sMsg) .}__XWK5  
{ CW1l;uwtU  
System.err.println(sMsg); 9p_?t'&>q  
} @a8lF$<  
} Tm"H9  
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y 4i3m(S  
/* R ]Ev=V'U  
**TestMethod.java LL<xyg
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*/ >a8iY|QY  
package NetFox; [8QK @5[  
;Gr {  
1I%u)[;>  
public class TestMethod { J3yK^@&&  
e#[Klh$]EW  
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public TestMethod()
"7cty\  
{ ///xx/weblogic60b2_win.exe O:?3B!wF  
try{ ;yNc7Vl  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); H(y`[B,}*  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); \%7*@&  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 2@S}x@^  
fileFetch.start(); (Yewd/T  
} qO{z{@jo55  
catch(Exception e){e.printStackTrace ();} ` GF w?G  
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} x/,;:S  
,z&S;
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Lc!2'Do;  
public static void main(String[] args) }nrjA0WN  
{ +&.zwniSS  
new TestMethod(); 15ailA&(Qm  
} fRS;6Jc  
} #xtH6\X  
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