http断点续传简单实现（java)

/* r]cq|Nv8:  
**SiteFileFetch.java ]'Eg2(wy  
*/ $,by!w'e:l  
package NetFox; D%o(HS\E  
import java.io.*; x+4K,r;  
import java.net.*; 7<]&pSt=  
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public class SiteFileFetch extends Thread { K_L7a>Fr  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Cydo~/  
long[] nStartPos; //开始位置 m   uO.  
long[] nEndPos; //结束位置 #1$4<o#M  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 A)9]^@,  
long nFileLength; //文件长度 3Ed  
boolean bFirst = true; //是否第一次取文件 eGQ4aQhi  
boolean bStop = false; //停止标志 (LTu=1  
File tmpFile; //文件下载的临时信息 m-uXQS^@G  
DataOutputStream output; //输出到文件的输出流 Vc9Bg2f5  
":+d7xR?o  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） I= :yfW  
public SiteFileFetch(SiteInfoBean bean) throws IOException wX)'
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{ zNo,PERG  
siteInfoBean = bean; s:6K'*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); j7&#R+f  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); xSN;vrLHR  
if(tmpFile.exists ()) N~/X.D4e#  
{ rR@]`@9  
bFirst = false; ]_B<K5  
read_nPos(); %%X/gvaJ  
} yWRIh*>nE  
else iSf%N>y'K  
{ \m)s"Sh.  
nStartPos = new long[bean.getNSplitter()]; i695P}J2  
nEndPos = new long[bean.getNSplitter()]; Pq+|*Y<|&  
} X~VI}dJ  
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} QmSj6pB>  
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public void run() [7.Num_L  
{ ek5j;%~g1  
//获得文件长度 4`l$0m@>  
//分割文件 ~\-=q^/!  
//实例FileSplitterFetch {91Y;p C  
//启动FileSplitterFetch线程 <#BK(W~$  
//等待子线程返回 [p'2#Et  
try{ 51eZfJB  
if(bFirst) A*0X~6W  
{ k8ILo)  
nFileLength = getFileSize(); 4S4MQ  
if(nFileLength == -1) Nk-xnTZ"  
{ STu(I\9  
System.err.println("File Length is not known!"); JzywSQ  
} }*!L~B!  
else if(nFileLength == -2) <FkaH8,7  
{
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System.err.println("File is not access!"); PYi<iSr  
} 8HLL3H0  
else T$M
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{ phb ;D  
for(int i=0;i<nStartPos.length;i++) )OQm,5F1  
{ J ##a;6@  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Y_]y :H  
} h
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for(int i=0;i<nEndPos.length-1;i++) AUF[hzA  
{ nWCJY:q;5  
nEndPos = nStartPos[i+1]; /z^v%l  
} ).,twf58  
nEndPos[nEndPos.length-1] = nFileLength; <k1muSe  
} Yqh-U%"'  
} v,Kum<oi?  
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!Usmm8!K  
//启动子线程 1^NC=IS9z  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 6%t6u3  
for(int i=0;i<nStartPos.length;i++) [Y
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{ $H@
  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), oAN,_1v)  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), p Cx_[#DrP  
nStartPos,nEndPos,i); EK>x\]O%T  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `>KNa"b%$  
fileSplitterFetch.start(); &'e+`\  
} T)22P<M8  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), FB?V<x  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); uh9b!8  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", V 7~9z\lW  
nEndPos = " + nFileLength); y /8iEs  
// fileSplitterFetch[nPos.length-1].start(); NlhC7  
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//等待子线程结束 +-t&li%F  
//int count = 0; (oiQ5s^f  
//是否结束while循环 '#A_KHD  
boolean breakWhile = false; 9BOn8p;yz  
}@$CS5w  
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while(!bStop) D
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{ ~,F]~|U7l  
write_nPos(); #bGYHN  
Utility.sleep(500); gYho$E  
breakWhile = true; 2PPb  
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for(int i=0;i<nStartPos.length;i++) :1t&>x=T  
{ v^/<2/E"?4  
if(!fileSplitterFetch.bDownOver) #l)o<Z  
{ wk'(g_DP  
breakWhile = false; D)L~vA/8b  
break; 1A;,"8kBd  
} XH0Vs.w  
} #
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if(breakWhile) Qe7 SH{  
break; 7Fa<m]k  
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,,EG"Um6  
//count++; 7]5+%[Dg!  
//if(count>4) ~PpU'[  
// siteStop(); !:vQg+S  
} b+AxTe("  
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 5B1,,8P  
System.err.println("文件下载结束！"); CucW84H`J  
} @!x7jPr  
catch(Exception e){e.printStackTrace ();} [=-,i#4  
} o2YHT \P n  
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<#Fex'4  
//获得文件长度 jtpk5 fJB  
public long getFileSize() ept:<!4  
{ {9@E[bWp#  
int nFileLength = -1; \Ff]}4  
try{ ]=|iO~WN  
URL url = new URL(siteInfoBean.getSSiteURL()); 0^2e^qf  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); X2~KNw  
httpConnection.setRequestProperty("User-Agent","NetFox"); REX/:sB<  
z __#PQ,n  
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int responseCode=httpConnection.getResponseCode(); 3!?QQT,!)  
if(responseCode>=400) x)q$.u+  
{ >9g^-~X;v  
processErrorCode(responseCode); E/% F0\B  
return -2; //-2 represent access is error I2z7}*<u  
} Ra~:O\Z  
;%>X+/.y0  
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String sHeader; M-!#-l  
Z +<Y.*6  
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for(int i=1;;i++) `Sj8IxO  
{ Frhm4H%,_R  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Np~qtR  
//Utility.log(in.readLine()); hL;??h,!_  
sHeader=httpConnection.getHeaderFieldKey(i); m|Z[8Tup  
if(sHeader!=null) i-k(/
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{ zcEpywNP  
if(sHeader.equals("Content-Length")) </fTn_{2s8  
{ <PO-S\N  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ov>`MCS,v  
break; zlh\P`  
} a ?wg~|g  
} BIvz55g  
else Y(R],9h8  
break; zzKU s"u  
} 127@ TN"  
} KA`)dMWL  
catch(IOException e){e.printStackTrace ();} wp/x|AV  
catch(Exception e){e.printStackTrace ();} $i `@0+:  
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Utility.log(nFileLength); xJvalb  
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return nFileLength; ,6
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} %#]/]B/4  
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=\<!kJ\yH  
//保存下载信息（文件指针位置） =gB{(   
private void write_nPos() {\=NZ\  
{ 4MgG]  
try{ }M\G  
output = new DataOutputStream(new FileOutputStream(tmpFile)); wK%x
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output.writeInt(nStartPos.length); /z(s1G.  
for(int i=0;i<nStartPos.length;i++) 9+>%U~U<  
{ KEr?&e  
// output.writeLong(nPos); k.F(*kh  
output.writeLong(fileSplitterFetch.nStartPos); IZ_ B $mo  
output.writeLong(fileSplitterFetch.nEndPos); 9l7 youZ]  
} 1`n ZK$  
output.close(); VqB9^qJ]!  
} &cx]7
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catch(IOException e){e.printStackTrace ();} w?c~be$  
catch(Exception e){e.printStackTrace ();} 4_
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} &-Z#+>=H(  
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//读取保存的下载信息（文件指针位置） OoAZ t  
private void read_nPos() bNz2Uo!0K  
{ e}"k8 ./  
try{ 1]jUiX=T  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); E!>l@ ki  
int nCount = input.readInt(); 6HR*)*>z_  
nStartPos = new long[nCount]; ]h&?^
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nEndPos = new long[nCount]; z:W1(/W~  
for(int i=0;i<nStartPos.length;i++) ~leLQsZ  
{ :&D$Q 4  
nStartPos = input.readLong(); Z@:R'u2Lk  
nEndPos = input.readLong(); }pPt- k  
} }Qvoms<k  
input.close(); wsCT9&p  
} ok9G9|HA  
catch(IOException e){e.printStackTrace ();} %6<2~  
catch(Exception e){e.printStackTrace ();}  *FoPs  
} A}n5dg
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private void processErrorCode(int nErrorCode) QmB,~x{j>  
{ X7"hTD  
System.err.println("Error Code : " + nErrorCode); e%DF9}M  
} 04<T2)QgK  
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//停止文件下载 4?&CK  
public void siteStop() s((_^yf  
{ _N`pwxpsb  
bStop = true; Tn3f5ka'  
for(int i=0;i<nStartPos.length;i++) EC|b7  
fileSplitterFetch.splitterStop(); gbRdng7(}  
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} 5Bc)QKh`l|  
} oE4hGt5x{  
//负责部分文件的抓取 p
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**FileSplitterFetch.java 6ypqnOTr  
*/ %4E7 Tu,1  
package NetFox; IN9o$CZ:  
9^c"HyR  
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import java.io.*; DWH)<\?  
import java.net.*; Q
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public class FileSplitterFetch extends Thread { Q-N.23\1  
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String sURL; //File URL \ o&i63u  
long nStartPos; //File Snippet Start Position 8Lpy`
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long nEndPos; //File Snippet End Position |KC
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int nThreadID; //Thread's ID fJC,ubP[5  
boolean bDownOver = false; //Downing is over @]h#T4z'  
boolean bStop = false; //Stop identical ptuW}"F  
FileAccessI fileAccessI = null; //File Access interface 93(  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Ic/<jFZXM  
{ JhDjY8?86  
this.sURL = sURL; :1>R~2  
this.nStartPos = nStart; |E]YP~h  
this.nEndPos = nEnd; }q ?iJ?P  
nThreadID = id; Z{n7z$s*  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /bylA`IMW  
} /a
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public void run() ()>\D  
{ j{P,(-  
while(nStartPos < nEndPos && !bStop) :7!/FBd  
{ 8LwbOR"  
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try{ 1.H"$D>TC  
URL url = new URL(sURL); ^HL#)fK2I  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); XfsCu>  
httpConnection.setRequestProperty("User-Agent","NetFox"); X>|.BvY|  
String sProperty = "bytes="+nStartPos+"-"; N]yk<55  
httpConnection.setRequestProperty("RANGE",sProperty); knBT(x'+  
Utility.log(sProperty); 6<t\KMd  
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InputStream input = httpConnection.getInputStream(); 4!gyFi6$  
//logResponseHead(httpConnection); W#y)ukRv  
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byte[] b = new byte[1024]; ,_lwT}*w  
int nRead; Qw5M\   
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 65J'uN  
{ >uJrq""+  
nStartPos += fileAccessI.write(b,0,nRead); 0 q3<RX>M%  
//if(nThreadID == 1) sfrh+o57  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Y9w=[[1  
} -GKelz?h>  
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Utility.log("Thread " + nThreadID + " is over!"); dF.T6b  
bDownOver = true; W'0wTZG  
//nPos = fileAccessI.write (b,0,nRead); t583Q/1@  
} @e0Q+
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catch(Exception e){e.printStackTrace ();} Zz3#Kt5t3  
} bo -Gh`  
} 'FUPv61()  
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~IWi@m{  
//打印回应的头信息 &'](T9kg=  
public void logResponseHead(HttpURLConnection con) R\Q%
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{ I] "$h]T  
for(int i=1;;i++) .N+xpxdG,  
{ Uq+ _#{2(  
String header=con.getHeaderFieldKey(i); P`%ppkzV6  
if(header!=null) (7wR*vO^  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); oF6MV&q/  
Utility.log(header+" : "+con.getHeaderField(header)); IIR?@/q  
else 6aK--k  
break; JX/d;N7a  
} Q:MsD.  
} V_1
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public void splitterStop() 0*"j:V  
{ i;xMf5Jz  
bStop = true; /uc/x+(_  
} j`GbI0,bT  
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} D7(t6C=FP  
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/* ^U?(g0<"  
**FileAccess.java 0X-2).nu  
*//文件访问(定位，写) \O?B9_  
package NetFox; stG&(M  
import java.io.*; &sgwY  
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public class FileAccessI implements Serializable{ _Kj.  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 &aQ)x  
RandomAccessFile oSavedFile; =arsoCa  
long nPos; eC{Z  
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*!/#39  
public FileAccessI() throws IOException M(E_5@?3  
{ *Kkw,qp/  
this("",0); )89jP088V  
} Rqz
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public FileAccessI(String sName,long nPos) throws IOException D` X6'PP  
{ 8} k,!R[J  
oSavedFile = new RandomAccessFile(sName,"rw"); Kzu9Qm-+z^  
this.nPos = nPos; pi}H.iF  
oSavedFile.seek(nPos); 5mNXWg7#]  
} b . j^US^  
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@/(7kh+  
public synchronized int write(byte[] b,int nStart,int nLen) -c?wEqa~2  
{ +"
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int n = -1; }_22wjm~  
try{ @b{u/:y  
oSavedFile.write(b,nStart,nLen); &FVlTo1  
n = nLen; 7uxPkZbb  
} E|;5Z*  
catch(IOException e) &RrQ()<as  
{
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e.printStackTrace (); tQaCNS$=  
} Hc%\9{zH  
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return n; X4G55]D$>  
} %Nl(Y@dD*  
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} d)ZSzq  
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/* L)'rM-nkFh  
**SiteInfoBean.java PEt8,,x<"  
*/ WN/#9]` P  
package NetFox; faOWhIG  
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public class SiteInfoBean { l_-n&(N2<[  
<&%1pZ/6.  
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private String sSiteURL; //Site's URL 5a!e

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private String sFilePath; //Saved File's Path PB67?d~  
private String sFileName; //Saved File's Name pNQkKDbL+  
private int nSplitter; //Count of Splited Downloading File LC\:xia{X  
J8BT%  
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public SiteInfoBean() 1 "7#|=1/  
{//nSplitter的缺省值为5 v@uaf=x-  
//default value of nSplitter is 5 {4aY}= -Q*  
this("","","",5); Q]5^Eiq8  
} 67\Ojl~(1  
*>p(]_s,  
{ DQE7kI  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) `$SEkYdt  
{ uEGPgYY(  
sSiteURL= sURL; GR[>mkW!M  
sFilePath = sPath; ^MHn2Cv/~  
sFileName = sName; *Yu\YjLPG  
this.nSplitter = nSpiltter; -yQ\3wli`  
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} {3(.c, q@  

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public String getSSiteURL() y2$;t'  
{ :t{vgi D9  
return sSiteURL; }R&5qpl  
} ]z=Vc#+!  
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public void setSSiteURL(String value) IPR tm!  
{ B4:l*P'  
sSiteURL = value; */^2RZg|W  
} u1{ym_  
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public String getSFilePath() <h_P+ nz  
{ :sVHY2x  
return sFilePath; 'c
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} zL}
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public void setSFilePath(String value) sK%Hx`  
{ _`Q It>R  
sFilePath = value; 0 {JK4]C  
} Kxl,] |e>  
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_/ }6  
public String getSFileName() ]AA%J@  
{ U\Ar*b)/T  
return sFileName; bLM"t0  
}
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public void setSFileName(String value) 1.0!H.>q  
{ }S vw,c  
sFileName = value; .y7)XLC  
} "?SOBA!vy  
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public int getNSplitter() \_*MJ)h)X  
{ -[pCP_`)u  
return nSplitter; HD:%
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} RzzFhU#r  
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public void setNSplitter(int nCount) %]<RRH.w  
{ \5[D7}  
nSplitter = nCount; 3IK(f.  
} %7]XW2u  
} .b#9q6F-/  
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7/|F9fF@M  
/* fNqmTRu  
**Utility.java 7SK3  
*/ \|~?x#aA  
package NetFox; !FB \h<6  
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public class Utility { lkg"'p{  
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public Utility() G;Wkm|  
{ 7V=MRf&xQ  
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} #H;hRl  
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//线程睡眠 }
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public static void sleep(int nSecond) 0F+zG)G"  
{ W`N}  
try{ W]
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Thread.sleep(nSecond); wHtJ_Y  
} Zlk,])9Q  
catch(Exception e) zkh hN"bX  
{
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e.printStackTrace (); oSn! "<x  
} Qsg/V]  
} 5 o#<`_=J  
{Z#e{~m#  
//日志 >I4p9y(u  
public static void log(String sMsg) |.(CIu~b   
{ 4bi NGl~  
System.err.println(sMsg); z
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} h`5YA89  
J%\
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public static void log(int sMsg) eyT>wma0  
{ 6 u-$  
System.err.println(sMsg); SOp=~

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} }!%JYG^!D  
} ~H^'al2PK  
> -y&$1  
:reP} Da7q  
/* 3`A>j"  
**TestMethod.java |(V?,^b^ro  
*/ &~~aAg  
package NetFox; `KpFH.k.K  
c~}={4M]  
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public class TestMethod { 76-jMcGi  
{~bIA!kAFI  
4^DVW*OiI  
public TestMethod() XXW]0{k:y  
{ ///xx/weblogic60b2_win.exe wG1y,u'  
try{ ;} lT  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); KVB0IXZC~  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); w66v\x~  
SiteFileFetch fileFetch = new SiteFileFetch(bean); S&4+ e:K  
fileFetch.start(); /!3ZWXY\  
} D|d4:;7  
catch(Exception e){e.printStackTrace ();} 7
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} _eJXi,  
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&{%MjKJ._  
public static void main(String[] args) Ia629gi5s  
{ `)R?nVb  
new TestMethod(); AF^T~?t  
} 2_;]  
} HH)"]E5  
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