http断点续传简单实现（java)

/* 8tL~FiHb"  
**SiteFileFetch.java LVGe]lD  
*/ 7#Ft|5$~q  
package NetFox; tw;}jh  
import java.io.*;
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import java.net.*; 'L'R9&o<X  
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public class SiteFileFetch extends Thread { ?9/G[[(  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 4s-!7  
long[] nStartPos; //开始位置 e ,(mR+a8  
long[] nEndPos; //结束位置 vs
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 =cI(d ,  
long nFileLength; //文件长度 P pb\6|*  
boolean bFirst = true; //是否第一次取文件 V gWRW7Se  
boolean bStop = false; //停止标志 ^q5#ihM  
File tmpFile; //文件下载的临时信息 XS#Qu=,-  
DataOutputStream output; //输出到文件的输出流 [,Gg^*umS  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） x5Bk/e'  
public SiteFileFetch(SiteInfoBean bean) throws IOException j#|ZP-=1_  
{ X?O[r3<  
siteInfoBean = bean; y[;>#j$  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); c 9Mz]1@f  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ?uu*
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if(tmpFile.exists ()) oH@78D0A  
{ Q &
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bFirst = false; HMXE$d=[  
read_nPos(); V3Bz Mw\9r  
} _BufO7`.  
else llq<egZpm  
{ rq{$,/6.  
nStartPos = new long[bean.getNSplitter()]; /ZX}Nc g  
nEndPos = new long[bean.getNSplitter()]; \bXa&Lq  
} yi[x}ffdE  
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} $4\j]RE!  
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public void run() +A+)=/i;  
{ mFeP9MfJ  
//获得文件长度 :jf3HG  
//分割文件 Wwo0%<2y  
//实例FileSplitterFetch 6]N.%Y[(  
//启动FileSplitterFetch线程 k6^Z~5 Sy  
//等待子线程返回
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try{ Jm@oDME_E  
if(bFirst) }V>T
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nFileLength = getFileSize();
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if(nFileLength == -1) )7@0[>  
{ P>T"cv  
System.err.println("File Length is not known!"); f$( e\++  
} 4i bc  
else if(nFileLength == -2) 'w/hw'
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{ \
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System.err.println("File is not access!"); d9ihhqq3}  
} ~&O%N  
else a*;b^Ze`v  
{ t^HRgY'NjM  
for(int i=0;i<nStartPos.length;i++) sLFl!jX  
{ hZ3bVi)L\  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); :&Nbw  
} ^Cmyx
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for(int i=0;i<nEndPos.length-1;i++) 0(Ij%Wi,  
{ a.'*G6~Qgw  
nEndPos = nStartPos[i+1]; |qLh5Ty  
} }G=M2V<L  
nEndPos[nEndPos.length-1] = nFileLength; e!`i3KYn"  
} `/g UV  
} VQI3G  
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//启动子线程 v=k$A  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; -di o5a  
for(int i=0;i<nStartPos.length;i++) !wNO8;(  
{ ]9L oZ)  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 4 :=]<sc,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 'yth'[  
nStartPos,nEndPos,i); *I'yH8F
cn  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); U.TA^S]`g  
fileSplitterFetch.start(); +"(jjxJm  
} ~ 1pr~  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Q&&@v4L  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); xPgBV~  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", bcR_E5x$  
nEndPos = " + nFileLength); H"KCK6  
// fileSplitterFetch[nPos.length-1].start(); 07)yG:q*x  
-N@|QK>  
]9XDS[<2`  
//等待子线程结束 -&;TA0~;  
//int count = 0; VX/#1StC  
//是否结束while循环 r/sNrB1U"y  
boolean breakWhile = false; :LTN!jj  
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while(!bStop) j9,P/K$:w  
{ s(^mZ -i  
write_nPos(); AEuG v}#  
Utility.sleep(500); V:27)]q  
breakWhile = true; 2Hdu:"j  
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for(int i=0;i<nStartPos.length;i++) sr}E+qf  
{ <or2  
if(!fileSplitterFetch.bDownOver) W l16`9  
{ -DCbko  
breakWhile = false; yBRC*0+Vy  
break; m3ff;,  
} 4sM.C9W  
} 4~=l}H>&  
if(breakWhile) 
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break; ?}7p"3j'z  
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, dp0;nkr  
//count++; lLD12d  
//if(count>4) ?q&T$8zc4  
// siteStop(); smLQS+UE  
} <1%$Vq  
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System.err.println("文件下载结束！"); Jo}eeJ;k  
} ZB&6<uw  
catch(Exception e){e.printStackTrace ();} }&e5$lB  
}
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//获得文件长度 qFNes)_r  
public long getFileSize() ;6wA"  
{ Z8oK2Dw  
int nFileLength = -1; !a<ng&H^U  
try{ EP+J
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URL url = new URL(siteInfoBean.getSSiteURL()); m6djeOl  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); UDni]P!E  
httpConnection.setRequestProperty("User-Agent","NetFox"); )ANmIwmC#  
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int responseCode=httpConnection.getResponseCode(); Faf&U%]*`  
if(responseCode>=400) '=6\v!  
{ x;')9/3  
processErrorCode(responseCode); PuO&wI]:  
return -2; //-2 represent access is error hL5|69E  
} nLiY%x`S  
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String sHeader; 39|MX21k  
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for(int i=1;;i++) QwJyY{O`  
{ yA>nli=  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); z~Q>V]a>;  
//Utility.log(in.readLine()); 
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sHeader=httpConnection.getHeaderFieldKey(i); 3t6LT  
if(sHeader!=null) T5:G$-q
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{ l\?c}7k  
if(sHeader.equals("Content-Length")) B+0hzkPY  
{ hG:|9Sol,  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); j w9b)  
break; \j)E5b+  
} 6x|jPb  
} $j?1g#  
else ~!3r&(  
break; PzR[KUK  
} 9$m|'$p3sG  
} o+9j?|M  
catch(IOException e){e.printStackTrace ();} xRsWI!d+|  
catch(Exception e){e.printStackTrace ();} TW>WHCAm  
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Utility.log(nFileLength); uOGw9O-d9  
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return nFileLength; X~i<g?]  
} hiw|2Y&`  
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//保存下载信息（文件指针位置） uXq. ]ub  
private void write_nPos() gl_^V&c  
{ TNr :pE<  
try{ BV+ Bk+  
output = new DataOutputStream(new FileOutputStream(tmpFile)); S/I/-Bp~  
output.writeInt(nStartPos.length); (2 a`XwR  
for(int i=0;i<nStartPos.length;i++) .-X8J t  
{ CsifKHI  
// output.writeLong(nPos); aoa)BNs  
output.writeLong(fileSplitterFetch.nStartPos); PAOJ\U  
output.writeLong(fileSplitterFetch.nEndPos); @oad,=R&  
} @Pz
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output.close(); "2T#MO/  
} :<#nTh_@\'  
catch(IOException e){e.printStackTrace ();} :$9tF>  
catch(Exception e){e.printStackTrace ();} M {Q;:  
} CC^'@~)?  

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//读取保存的下载信息（文件指针位置） ~<OSYb  
private void read_nPos() *U\`CXn;  
{ LRMx<X8  
try{ H1(Uw:V8  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 1|6%evPu(  
int nCount = input.readInt(); @[
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nStartPos = new long[nCount]; }k G9!sf  
nEndPos = new long[nCount]; A7hVHxNJ-  
for(int i=0;i<nStartPos.length;i++) y {<9]'  
{ Vr1<^Ib  
nStartPos = input.readLong(); VD]zz ^  
nEndPos = input.readLong(); JO"<{ngsQ  
} DXK}-4"\  
input.close(); JOim3(5?s  
} A:9?ZI/X  
catch(IOException e){e.printStackTrace ();} '1)$'
 
catch(Exception e){e.printStackTrace ();} Eue~Y+K*b  
} }sO&. ME  
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private void processErrorCode(int nErrorCode) eSmLf*\G  
{ yU}
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System.err.println("Error Code : " + nErrorCode); 8d-t|HkN  
} df#$9-  
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//停止文件下载 =-lb)Z"d  
public void siteStop() u21EP[[,  
{ "djw>|,N<  
bStop = true; tlp@?(u  
for(int i=0;i<nStartPos.length;i++) 3az&<Pqb  
fileSplitterFetch.splitterStop(); be^6i:  
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} } c}_<#I  
} w+E,INdi  
//负责部分文件的抓取 *6F[t.Or  
**FileSplitterFetch.java Yv!a88+A8M  
*/ E6gI,f/p0X  
package NetFox; ]Y8<`;8/  
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import java.io.*; B[-v[K2  
import java.net.*; *zL}&RUKM  
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public class FileSplitterFetch extends Thread { oVfLnI;  
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//<nr\oP  
String sURL; //File URL j*jo@N|  
long nStartPos; //File Snippet Start Position }\:NuTf  
long nEndPos; //File Snippet End Position G&V/Gj8  
int nThreadID; //Thread's ID krvp&+uX  
boolean bDownOver = false; //Downing is over I\[_9  
boolean bStop = false; //Stop identical #c?j\Y9nz  
FileAccessI fileAccessI = null; //File Access interface *8_wYYH  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException z]?N+NHOA  
{ l6 H|PR{  
this.sURL = sURL; \(Y\|zC'0$  
this.nStartPos = nStart; :G2k5xD/E  
this.nEndPos = nEnd; a^zibPG  
nThreadID = id; c%G{#}^2  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /M4{Wc  
} T iiWp!mX  
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public void run() wlk4*4dKn  
{ L(-b@Joh  
while(nStartPos < nEndPos && !bStop) >X4u]>X  
{ ZR?yDgL  
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r^paD2&}  
try{ DLMM/WJg@  
URL url = new URL(sURL); D9 |n)f  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (ECnMti+  
httpConnection.setRequestProperty("User-Agent","NetFox"); iQ fJ  
String sProperty = "bytes="+nStartPos+"-"; E!l!OtFL  
httpConnection.setRequestProperty("RANGE",sProperty); 1@R Db)<V  
Utility.log(sProperty); -w_QJ_z_  
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InputStream input = httpConnection.getInputStream();
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//logResponseHead(httpConnection); )~] (&  
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byte[] b = new byte[1024]; <_tT<5'[$u  
int nRead; D (mj7oB  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ;y\IqiA{o  
{ s,=i_gyPQ  
nStartPos += fileAccessI.write(b,0,nRead); G]i/nB  
//if(nThreadID == 1) s<_)$}  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); }O^zl#  
} F
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Utility.log("Thread " + nThreadID + " is over!"); 3.W@ }  
bDownOver = true; 3
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//nPos = fileAccessI.write (b,0,nRead); |>htvDL  
} LBsluT  
catch(Exception e){e.printStackTrace ();} >>o
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} OJ$]V,Z00x  
} -[!P!d=  
*ikc]wQr$  
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//打印回应的头信息 5Z\#0":e  
public void logResponseHead(HttpURLConnection con) ws|;`  
{ L>%o[tS  
for(int i=1;;i++) e5B Qr$j  
{ ~ga`\%J  
String header=con.getHeaderFieldKey(i); TXk
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if(header!=null) 4 G-wd  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); `_{`l4i5  
Utility.log(header+" : "+con.getHeaderField(header)); J}+6UlD  
else "a1n_>#Fb  
break; 6&l+0dq  
} H_ox_ u}  
} Nkl_Ho,  
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public void splitterStop() !l 1fIc  
{ hn=[1<#^(  
bStop = true; q
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} Boz@bl mCB  
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} "zFNg';  
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/* d'$T4yA  
**FileAccess.java Z->p1xkX  
*//文件访问(定位，写) :^x?2% ~K.  
package NetFox; C #6dC0  
import java.io.*; dJ""XaHqf  
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public class FileAccessI implements Serializable{ p)
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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 EC8b=B<DE  
RandomAccessFile oSavedFile; .dQQoyR+O  
long nPos; +H#U~p$  
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public FileAccessI() throws IOException meks RcF  
{ mPP`xL?T  
this("",0); F
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} 5~WGZc  
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public FileAccessI(String sName,long nPos) throws IOException /&{$ pM|?  
{
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oSavedFile = new RandomAccessFile(sName,"rw"); lB
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this.nPos = nPos; q^L<X)  
oSavedFile.seek(nPos); p4i]7o@  
} 16i"Yg!*  
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public synchronized int write(byte[] b,int nStart,int nLen) V6#K2  
{ wz.6du6-  
int n = -1; eT8}  
try{ mJ`A_0  
oSavedFile.write(b,nStart,nLen); {aJJ`t  
n = nLen; >Ll$p0W  
} (B-43!C  
catch(IOException e) JEgx@};O  
{ Ch%m  
e.printStackTrace (); `zt_7MD  
} mzc 4/<th  
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return n; Xy &uZ  
} ]t
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} S&Ee,((E(  
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/* =)` p_W  
**SiteInfoBean.java ~~,rp) )  
*/ &gE 75B  
package NetFox; WJ9cZL  
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public class SiteInfoBean { (%:>T Q(  
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private String sSiteURL; //Site's URL 5pRV3K{H  
private String sFilePath; //Saved File's Path )&<=.q  
private String sFileName; //Saved File's Name %9#gB  
private int nSplitter; //Count of Splited Downloading File U"4?9. k  
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public SiteInfoBean() EmT`YNuc  
{//nSplitter的缺省值为5 [ dE.
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//default value of nSplitter is 5 *79m^  
this("","","",5); rUjdq/I:Z  
} Iu35#j  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) J!*/a'Cv  
{ LR,7,DH$9'  
sSiteURL= sURL; P0-Fc@&Y  
sFilePath = sPath; l@hjP1o  
sFileName = sName; Lh-`OmO0>F  
this.nSplitter = nSpiltter; a3>zoN  
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}  l"zUv  
;!T{%-tP  

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public String getSSiteURL() 6R29$D|HFO  
{ w_iamqe,  
return sSiteURL; 9OfFM9(:  
} N6[i{;K@N{  
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public void setSSiteURL(String value) ib0g3p-Lc  
{ '?yCq$&  
sSiteURL = value; +tN&a  
} te4= S  
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public String getSFilePath() |k{-l!HI  
{ efuK  
return sFilePath; w h$jr{  
} 2PSTGG8JV  
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public void setSFilePath(String value) zG c[Z3N  
{ qsg>5E  
sFilePath = value; '?GQ~Bf<>  
} G7* h{nE  
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public String getSFileName() 5GAy "Xd  
{ C
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return sFileName; 5QWNZJ&}d  
} xUYow  
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public void setSFileName(String value) |&hU=J o  
{ =J|sbY"]  
sFileName = value; I/UQ'xx  
} 04y!\  
4^!4eyQ^  
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public int getNSplitter() IvW@o1Q  
{ U 0ZB^`  
return nSplitter; }BN\/;<A  
} >v0:qN7|  
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public void setNSplitter(int nCount) PX3  
{ TV{)n'aA  
nSplitter = nCount; IM-`<~(I#  
} f:%SW  
} "]]q} O?  
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/* V8'`nuC+  
**Utility.java U4w
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*/ i;lE
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package NetFox; &jJckT  
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w4:
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public class Utility { @ u1Q-:  
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public Utility() z Z%/W)t  
{ )
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} YMAQ+A!  
^"tqdeCb=  
//线程睡眠 I>((o`  
public static void sleep(int nSecond) g[!Cj,  
{ 2xmT#m  
try{ <PD|_nZ
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Thread.sleep(nSecond); HtzMDGV<  
} qWB%),`j>  
catch(Exception e) q 22/_nSC  
{ %}F"*.  
e.printStackTrace (); zPQ$\$7xB  
} om7`w ]  
} D9ywg/Q91  
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//日志 slSR=XOG  
public static void log(String sMsg) zH+<bEo=1=  
{ d[U1.SNL  
System.err.println(sMsg); 5<r)+?!n  
} v>^jy8$  
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public static void log(int sMsg) n^6TP'r  
{ @}G|R\2P  
System.err.println(sMsg); B*Cb6'Q  
} 4sd-zl$Of  
} U$$3'n  
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/* 4[H,3}p9H  
**TestMethod.java -wIM0YJ  
*/ R`7n^,  
package NetFox; c'lIWuL)  
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public class TestMethod { t>@yv#  
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public TestMethod() Wy,"cT  
{ ///xx/weblogic60b2_win.exe w#d}TY  
try{ 0hZxN2r  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 2?H@$-x>  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); [EOMCH2Ki  
SiteFileFetch fileFetch = new SiteFileFetch(bean); w}b<D#0XC  
fileFetch.start(); GFY-IC+fc  
} 'Ix5,^M}B  
catch(Exception e){e.printStackTrace ();} g$gVm:=  
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} Vd[2u  
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public static void main(String[] args) 6DO0zNTY  
{ Z#LUez;&t#  
new TestMethod(); m^c%]5$  
} KY8^BjY@  
} Lo5Jb6nm  
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