http断点续传简单实现（java)

/* )iC@n8f7o  
**SiteFileFetch.java S1~EJa5H  
*/ Z"Q9^;0%  
package NetFox; 
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import java.io.*; x<w-j[{k_K  
import java.net.*; @Wm:Rz  
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public class SiteFileFetch extends Thread { -#4QY70H t  
3 Sf':N`u  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ?Ec{%N%  
long[] nStartPos; //开始位置 GKUjtPu  
long[] nEndPos; //结束位置 k MV1$  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 OM7AK B=S  
long nFileLength; //文件长度 fV6ddh  
boolean bFirst = true; //是否第一次取文件 'F/uD1;  
boolean bStop = false; //停止标志 c%wztP;L  
File tmpFile; //文件下载的临时信息 jc!V|w^  
DataOutputStream output; //输出到文件的输出流 %ib7)8Ki0  
z wwJyy%/  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） nu|,
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public SiteFileFetch(SiteInfoBean bean) throws IOException C(>g4.-p8  
{ h'vBWtMa  
siteInfoBean = bean; =l] lwA-  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Ed_Fx'  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 5~[][VV^  
if(tmpFile.exists ()) [T[]U  
{ 5V/]7>b1  
bFirst = false; ,|#biT-<T  
read_nPos(); @0tX,Z9  
} i3L2N~:V  
else +4qR5
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{ >lJTS t5{  
nStartPos = new long[bean.getNSplitter()]; eqOT@~H  
nEndPos = new long[bean.getNSplitter()]; TB<$9FCHK  
} {7$jwk  
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} ,5T1QWn^f  
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public void run() *].qm g%  
{ j]-_kjt  
//获得文件长度 P_p\OK*l]o  
//分割文件  
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//实例FileSplitterFetch |v#D}E  
//启动FileSplitterFetch线程 !N][W#:  
//等待子线程返回 UbIUc}ge  
try{ =jxy4`oF  
if(bFirst) "|,KXv')  
{ ~GJ;;v1b2  
nFileLength = getFileSize(); /Q89y[  
if(nFileLength == -1) QTN24 q4  
{ #_IuB) qy  
System.err.println("File Length is not known!"); {+Wknm%  
} oxI?7dy5  
else if(nFileLength == -2) 7GErh,  
{ &U([Wd?E2  
System.err.println("File is not access!"); BbL]0i  
} GZuWAa  
else BT$Oh4y4  
{ 3U!=R-  
for(int i=0;i<nStartPos.length;i++) |S<!'rY  
{ gg#lI|  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ~oK0k_{~  
} g2M1zRm;  
for(int i=0;i<nEndPos.length-1;i++) ^;[_CF_  
{ ]!jfrj  
nEndPos = nStartPos[i+1]; |]Hr"saO0  
} +n%8
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nEndPos[nEndPos.length-1] = nFileLength; )7#3n(_np  
} N K@6U_/W  
} TnKOr~@*  
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//启动子线程 }!|$;3t+c  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; E]a;Ydf~  
for(int i=0;i<nStartPos.length;i++) q]Xu #:X  
{ 6p3cMJ'8y  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), XW^Pz(  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), xh25 *y  
nStartPos,nEndPos,i); i],~tT|P  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); uz20pun4B  
fileSplitterFetch.start(); O@dK^o  
} bTAY5\wB  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,C
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); [ `_sH\  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", w?M"`O(  
nEndPos = " + nFileLength); &5B/>ag1!  
// fileSplitterFetch[nPos.length-1].start(); 2FO<Z %Y  
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B T {cTj0W  
//等待子线程结束 _~P&8  
//int count = 0; hKnV
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//是否结束while循环 <QaUq`,  
boolean breakWhile = false; mjk<FXW  
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while(!bStop) 4/ q BD  
{ +Oo-8f*  
write_nPos(); ;'[?H0Jw'  
Utility.sleep(500); y~M6  
breakWhile = true; +Ll29Buyi  
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for(int i=0;i<nStartPos.length;i++) $DnR[V}rR!  
{ &wu1Zz[qcz  
if(!fileSplitterFetch.bDownOver) Q{miI N  
{ ,KPrUM}  
breakWhile = false; m?8o\|i,  
break; X_Pbbx_j  
} z-sq9Qp&x  
} GyFA1%(o  
if(breakWhile) Z^WI~B0nt  
break; YzEOfHL,  
r5$!41   
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//count++; {FILt3f;  
//if(count>4) *{p:C  
// siteStop(); N6A|  
} x~D8XN{  
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System.err.println("文件下载结束！"); I,]q;lEMt  
} :RBeq,QaO  
catch(Exception e){e.printStackTrace ();} iHQ$L# 7  
} Z;0<k;#T(p  
*#?9@0b@  
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//获得文件长度 -0NkAQrg  
public long getFileSize() )?LZg<<  
{ >dwWqcP  
int nFileLength = -1; Lso%1M  
try{ A4KkX  
URL url = new URL(siteInfoBean.getSSiteURL()); OekE]`~w  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 'b
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httpConnection.setRequestProperty("User-Agent","NetFox"); =k1sF3.V'c  
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int responseCode=httpConnection.getResponseCode(); s8';4z  
if(responseCode>=400) I'2I'x\M  
{ 8"V1h72vcW  
processErrorCode(responseCode); %`/F>`  
return -2; //-2 represent access is error z XUr34jF  
} fy&u[Jd{  
#nZPnc:  
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String sHeader; !g#y$  
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}"kF<gG1  
for(int i=1;;i++) l=$?#^^ /  
{ Wk!<P" nHd  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ?@6Zv$vZ  
//Utility.log(in.readLine()); >
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sHeader=httpConnection.getHeaderFieldKey(i); TDy$Mv=y  
if(sHeader!=null) $}us+hGZ  
{ UDgX A  
if(sHeader.equals("Content-Length")) 'Ddzlip  
{ E9@Sc>e  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 7$IR^  
break; I"KosSs  
} ^E+fmY2a  
} Qj|tD+<  
else <;1M!.)5  
break; {qCFd  
} E!L_"GW  
} q[+KQ,  
catch(IOException e){e.printStackTrace ();} X7tBpyi  
catch(Exception e){e.printStackTrace ();} 4#ikdjB;  
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Utility.log(nFileLength); oP:R1<  
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return nFileLength; KYz@H#M  
} g{kjd2  
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t7,$u-  
//保存下载信息（文件指针位置） p+7#`iICE  
private void write_nPos() 4|4[3Ye7u:  
{ @_ UI;*V  
try{ zp``e;gY  
output = new DataOutputStream(new FileOutputStream(tmpFile)); vM:c70=  
output.writeInt(nStartPos.length); t=jG$
A  
for(int i=0;i<nStartPos.length;i++) r!|h3*YA  
{ Ip *8R]W  
// output.writeLong(nPos); Pw6%,?lQ  
output.writeLong(fileSplitterFetch.nStartPos); 38:5g_  
output.writeLong(fileSplitterFetch.nEndPos); {7_C|z:'p&  
} &7
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output.close(); (iJ /  
} /2tPd  
catch(IOException e){e.printStackTrace ();} QpS7nGev  
catch(Exception e){e.printStackTrace ();} s E;2;2u"  
} 82o|(pw  
<vxTfE@>bp  
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//读取保存的下载信息（文件指针位置） (''w$qq"D  
private void read_nPos() 7=qvu&{  
{ 9j5-/   
try{ 3[ xHY@c  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); /R>YDout}  
int nCount = input.readInt(); BE54L+$p  
nStartPos = new long[nCount]; ~4mRm!DP  
nEndPos = new long[nCount]; Ua~8DdW  
for(int i=0;i<nStartPos.length;i++) 7d+0'3%  
{ /1Ss |.  
nStartPos = input.readLong(); N0 mhgEA  
nEndPos = input.readLong(); <KI>:@|Sc  
} :EH>&vm  
input.close(); 1hc`s+N  
} O.-A)S@  
catch(IOException e){e.printStackTrace ();} kX)*:~*  
catch(Exception e){e.printStackTrace ();} 0+.<BOcW5  
} =p:~sn#  
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private void processErrorCode(int nErrorCode) g(G$*#}o8A  
{ SN[ar&I  
System.err.println("Error Code : " + nErrorCode); P5GV9SA  
} a=6@} l1<  
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//停止文件下载 TpdYU*z_Br  
public void siteStop() 9`KFJx6D  
{ b S'dXP  
bStop = true; Cj/!m  
for(int i=0;i<nStartPos.length;i++) {Eqx'j  
fileSplitterFetch.splitterStop(); `_BmVms  
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{z
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} $)KNpdXh  
} SA%)xGRW  
//负责部分文件的抓取 9 aKU}y  
**FileSplitterFetch.java QB;TQZ  
*/ yf4 i!~  
package NetFox; {CFy %  
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import java.io.*; ,-DU)&dF  
import java.net.*; I$XwM  
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public class FileSplitterFetch extends Thread { 0<^Qj.(9  
Vo|[Z)MO`  
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String sURL; //File URL ]3Jb$Q@  
long nStartPos; //File Snippet Start Position C^:{y  
long nEndPos; //File Snippet End Position ~4xn^.w  
int nThreadID; //Thread's ID ,|j\x  
boolean bDownOver = false; //Downing is over z.OJ1vY7  
boolean bStop = false; //Stop identical ?JW/Stua
 
FileAccessI fileAccessI = null; //File Access interface Jid_&\  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException "{c@}~  
{ CioS}K  
this.sURL = sURL; \6pQ&an  
this.nStartPos = nStart; Gh<#wa['}  
this.nEndPos = nEnd; #F6M<V'  
nThreadID = id; [jGE{<Je  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 @4Q/J$  
} F;Q'R|HQ  
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public void run() K~fWZT3]  
{ xU(b:D Z  
while(nStartPos < nEndPos && !bStop) st>%U9  
{ rqKK89fD'  
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try{ |3hNTH?  
URL url = new URL(sURL); Ix~rBD9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); mcs!A/]<  
httpConnection.setRequestProperty("User-Agent","NetFox"); U8</aQLGF  
String sProperty = "bytes="+nStartPos+"-"; 2tQ?=V(Di  
httpConnection.setRequestProperty("RANGE",sProperty); Wq?vAnLbk  
Utility.log(sProperty); <oSx'_dc  
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InputStream input = httpConnection.getInputStream(); 8~O0P=  
//logResponseHead(httpConnection); B3I0H6O  
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byte[] b = new byte[1024]; \3hFb,/4k  
int nRead; y(Em+YTD  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 6=*n$l#}  
{ c_aj-`BKp  
nStartPos += fileAccessI.write(b,0,nRead); kZR(0, W  
//if(nThreadID == 1) dl6Ju  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos);  "Id1H  
} NS "1zR+  
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Utility.log("Thread " + nThreadID + " is over!"); o@L '|#e  
bDownOver = true; (?i4P5s[!  
//nPos = fileAccessI.write (b,0,nRead); }}oIZP\qM  
} " BU4\QF-  
catch(Exception e){e.printStackTrace ();} *@WBaN+  
} =<AG}by![  
} j!@,r^(  
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//打印回应的头信息 0%yPuY>  
public void logResponseHead(HttpURLConnection con) w BoP&l  
{ Cn_r?1{W  
for(int i=1;;i++) M} +s_h
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{ 2;w> w#}>  
String header=con.getHeaderFieldKey(i);
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if(header!=null) we kb&?  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Fz| r[  
Utility.log(header+" : "+con.getHeaderField(header)); d^0-|sx  
else vOl3utu7  
break; .sb0|3&  
} u_b6u@r7  
} n;>
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public void splitterStop() F3x*dq2  
{ }^*`&Lh  
bStop = true; =>O{hT^F  
} *=Ma5J.  
]}.|b6\  
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} wBEBj7(y  
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/* 7324#HwS  
**FileAccess.java 5JG`FRW!  
*//文件访问(定位，写) {5+ 39=(  
package NetFox; (R9"0WeF  
import java.io.*; 2<d'!cm  
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public class FileAccessI implements Serializable{ _P%PjFQ)  
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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 ?iL-2I3*  
RandomAccessFile oSavedFile; EH'eyC-B<  
long nPos; ^__P;Gr`  
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public FileAccessI() throws IOException 8[a N5M]  
{ Ft_g~]kZo  
this("",0); FR\r/+n:t0  
} _j~y;R)  
!|cM<}TF,  
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public FileAccessI(String sName,long nPos) throws IOException },O7NSG<o  
{ <Rz[G+0S=  
oSavedFile = new RandomAccessFile(sName,"rw"); zv^+8h7k  
this.nPos = nPos; %2beoH'  
oSavedFile.seek(nPos); ;x/.8fA  
} |_a^+!P  
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public synchronized int write(byte[] b,int nStart,int nLen) ]
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{ LwH+X:?i  
int n = -1; t{Ks}9
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try{ f+Fzpd?wS  
oSavedFile.write(b,nStart,nLen); ft!D2M  
n = nLen; x@|10GC#:  
} _J,*0~O$  
catch(IOException e) Jt)J1CAYo  
{ F'ez{B\AX  
e.printStackTrace (); K
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} af/0e}-  
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return n; q~{O^,4S  
} *]DO3Zw'  
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n+s=u$%qn  
} f^Q)lIv  
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/* tnq ZlS  
**SiteInfoBean.java #=Whh 9-d  
*/ =n;LP#(h?  
package NetFox; semTAoqH  
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public class SiteInfoBean { !)`m mr  
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private String sSiteURL; //Site's URL 1TgD;qX  
private String sFilePath; //Saved File's Path +77j2W_0  
private String sFileName; //Saved File's Name :2~2j-m  
private int nSplitter; //Count of Splited Downloading File #6#%y~N
 
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public SiteInfoBean() FWLLbL5t  
{//nSplitter的缺省值为5 oYWHO<b  
//default value of nSplitter is 5 k~JTQh*,w  
this("","","",5); .8wF> 8  
} S=$ \S9  
%)e&"mq!|  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) = jTC+0u  
{ -8SZ}J  
sSiteURL= sURL; cHnd gUW]  
sFilePath = sPath; |"}rC >+  
sFileName = sName; A|m0.'/  
this.nSplitter = nSpiltter; QjTs$#eMW  
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i  
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} $wk(4W8E  
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public String getSSiteURL() :S+Bu*OyH
 
{ 0.B'Bvn=s2  
return sSiteURL; _V3}F1?W  
} /^`do3a}  
d 0:;IUG  
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public void setSSiteURL(String value) %KR2Vlh0  
{
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sSiteURL = value; bq{eu#rQJ  
} mqiCn]8G  
=ibKdPtTh^  
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public String getSFilePath() IkQ,#Bsb[  
{ bFJ>+ {#  
return sFilePath; 9Wdx"g52_D  
} so@ijl4{Z  
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public void setSFilePath(String value) mD,fxm{G  
{ &InF
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sFilePath = value; gbFHH,@  
} L(HAAqRn
J  
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public String getSFileName() ZD<e$PxxCd  
{ O 2+taB  
return sFileName; 3WPZZN<K9  
} /WIH#M  
iVb7>
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/7WdG)'  
public void setSFileName(String value) `_3Gb  
{ ?4_ME3$t  
sFileName = value; $WsyAUl  
} 3k:`7E.  
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%D`j3cEp@  
public int getNSplitter() QF$s([  
{ (?[%u0%_  
return nSplitter; _I0=a@3  
} +rka5ts  
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public void setNSplitter(int nCount) Po\d!  
{ N <M6~  
nSplitter = nCount;  bDq<]h_7  
} xr31<
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} WFvVu3  
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t* =i8`8  
/* L^Fb;sJYI  
**Utility.java Gf-GDy\{  
*/ *d-JAE  
package NetFox; C-^8;xd  
r(g#3i4Q  
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public class Utility { jN/snU2\0  
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public Utility() JcC2Zn6  
{ 7Liy
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} ((6?b5[  
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//线程睡眠 (bD#PQXzm  
public static void sleep(int nSecond) Xc<Hm  
{ MSe>1L2=  
try{ AH^ud*3F  
Thread.sleep(nSecond); IB^vEY!`6_  
} jM>;l6l  
catch(Exception e) qCm8R@  
{ VwT&A9&{8  
e.printStackTrace (); .RWq!Z=)3  
} 5a:YzQ4  
} OUy}1%HY  
96%N  
//日志 "7w=LhzV[$  
public static void log(String sMsg) 'T]Ok\  
{ %<MI]D  
System.err.println(sMsg); HE+
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} % "^CrG  
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/{-J_+u*%  
public static void log(int sMsg) -`PLewvX  
{ 8(* ze+8  
System.err.println(sMsg); :DFtH13qO  
} m>!aI?g  
} zT'(I6S:)  
Q 34-a"6)  
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/* J>fq5  
**TestMethod.java CT(HTu  
*/ S~^]ib0  
package NetFox; /&5:v%L  
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public class TestMethod { CUj$ <ay=  
u|(Iu}sE=  
b\H,+|i
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public TestMethod()
J4?SC+\  
{ ///xx/weblogic60b2_win.exe xj JoWB  
try{ VI)hA ^S  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); J5}?<Dd:  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Z*.rv t  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Q>TNzh  
fileFetch.start(); jV#1d8qm  
} WPPDvB  
catch(Exception e){e.printStackTrace ();} /`7G7pQ+  
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} 8]WcW/1r !  
s 4n<k]d  
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public static void main(String[] args) &0OH:P%  
{ B.#-@  
new TestMethod(); >bg{  
} hfs QAa  
} bUc++M
 
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