http断点续传简单实现（java)

/* +)zDA:2Wa"  
**SiteFileFetch.java f?Z|>3.2  
*/ D@#0dDT  
package NetFox; XjxPIdX_H  
import java.io.*; #
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import java.net.*; n"iNKR>nW  
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public class SiteFileFetch extends Thread { N ,+(>?yE  
* flWL  
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SiteInfoBean siteInfoBean = null; //文件信息Bean B=r0?%DX"1  
long[] nStartPos; //开始位置 \9'!"-i  
long[] nEndPos; //结束位置 p'gb)nI  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 I'dj.  
long nFileLength; //文件长度 cs t&0  
boolean bFirst = true; //是否第一次取文件 W+.{4K  
boolean bStop = false; //停止标志 inZi3@h)T  
File tmpFile; //文件下载的临时信息 jM]d'E?ZLA  
DataOutputStream output; //输出到文件的输出流 \2j|=S6  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ka#K [qI  
public SiteFileFetch(SiteInfoBean bean) throws IOException *o!l/>4g  
{ @7fm1b  
siteInfoBean = bean; <FQFv IKg  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); jP+ pA e  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 2)=la%Nx  
if(tmpFile.exists ()) U,'EF[t  
{ vnTq6:f#M  
bFirst = false; kQIfYtT  
read_nPos(); .A(i=!{q  
} |:N>8%@6c  
else * MEe,4  
{ 9s(i`RTM  
nStartPos = new long[bean.getNSplitter()]; x~EKGoz3  
nEndPos = new long[bean.getNSplitter()]; Rjq a_hxrS  
} %kq ^]S2O  
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} 9#Bx]wy  
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public void run() Pxqiv9D<R  
{ +}U2@03I  
//获得文件长度 ~,gLplpG0  
//分割文件 ~r&D6Y  
//实例FileSplitterFetch TY~Vi OC  
//启动FileSplitterFetch线程 x,\!DLq:p  
//等待子线程返回 iDw.i"b  
try{ (ND
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if(bFirst) m2O&2[g  
{ jgq{p
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nFileLength = getFileSize(); 5ITq?%{M  
if(nFileLength == -1) @VK6JjIq  
{ 6G}c1nWU  
System.err.println("File Length is not known!"); OJpj}R  
} 'E-FO_N  
else if(nFileLength == -2) ^C7C$TZS  
{ G6Nb{m  
System.err.println("File is not access!"); \ha-"Aqze3  
} )7Ixz1I9g  
else A=X-;N#  
{ )xt4Wk/  
for(int i=0;i<nStartPos.length;i++)
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{ =X@
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); f-D>3qSS  
} =cn~BnowY  
for(int i=0;i<nEndPos.length-1;i++) ?Ht=[l=  
{ )Gb,^NGr  
nEndPos = nStartPos[i+1]; e:E# b~{  
} ah+j!e  
nEndPos[nEndPos.length-1] = nFileLength; PsbG|~  
} 6D/tK|  
}
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h e&V# #  
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//启动子线程 mU@xcN
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; <lj\#'G3  
for(int i=0;i<nStartPos.length;i++) R ]P;sk5  
{ >1ZJ{se  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6P*O&1hv  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),
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nStartPos,nEndPos,i); 8r^ ~0nm  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); WYszk ,E  
fileSplitterFetch.start(); Q7GY3X*kA  
} %4,?kh``D  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), m|F:b}0Hb  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); wz=z?AZW  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", HnU Et/  
nEndPos = " + nFileLength); ,@.EpbB  
// fileSplitterFetch[nPos.length-1].start(); VLdB_r3lQ  
1'O0`Me>#  
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//等待子线程结束 Uc&iZFid2K  
//int count = 0; Uu'dv#4Iw  
//是否结束while循环 $Q/Ya@o  
boolean breakWhile = false; :=fvZAWD  
iM5vrz`n  
hs(W;tR@W  
while(!bStop) ;LMWNy4  
{ c1%rV`)]  
write_nPos(); FjFwvO_.  
Utility.sleep(500); Fo}7hab  
breakWhile = true; _Y!sVJ){,c  
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for(int i=0;i<nStartPos.length;i++) Lh ap4:  
{ /!T> b:0  
if(!fileSplitterFetch.bDownOver) S
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{ CDdkoajBa  
breakWhile = false; A'-_TFwW  
break; c\.P/~  
} ,.v7FM^gO  
} v}[dnG  
if(breakWhile) \#6Fm_b]u  
break; ,}
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//count++; qSD9Pue  
//if(count>4) \ZH&LPAY  
// siteStop(); qZ X/@Yxz  
} GwLFL.Ke  
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System.err.println("文件下载结束！"); yI)~]K r  
} Xy7Z38G  
catch(Exception e){e.printStackTrace ();} jd:B \%#![  
} "A[ b rG  
;t(f1rPyE  
q
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//获得文件长度 S$[k Q|Am  
public long getFileSize() {{!Y]\2S  
{ 
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int nFileLength = -1; kWW w<cA  
try{ F
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URL url = new URL(siteInfoBean.getSSiteURL()); =6T 4>rP  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Cifd21v4  
httpConnection.setRequestProperty("User-Agent","NetFox"); ll<NIdf\r  
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int responseCode=httpConnection.getResponseCode(); -iN.Iuc{b_  
if(responseCode>=400) jH*)%n5,\  
{ Q8qz*v]{  
processErrorCode(responseCode); =Ho"N`Qy  
return -2; //-2 represent access is error lMifpK  
} h(' )"  
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String sHeader; y
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for(int i=1;;i++) %2l7Hmp4H  
{ @pza>^wk  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); JPx7EEkZR4  
//Utility.log(in.readLine()); ;#k-)m%  
sHeader=httpConnection.getHeaderFieldKey(i); )qU7`0'8  
if(sHeader!=null) (@sp/:`6  
{ R,_d1^|*w  
if(sHeader.equals("Content-Length")) Vpp&|n9^  
{ Y+-xvx :  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 6Bt=^~d  
break; m{%t?w$Au  
} ;4#D,zlO^  
} !<n"6KA.  
else |m G7XL,  
break; z/]q)`G  
} 0$P/jt  
} buMqF-j  
catch(IOException e){e.printStackTrace ();} -J0WUN$2*  
catch(Exception e){e.printStackTrace ();} #exss=as/  
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Utility.log(nFileLength); `a]44es9q  

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return nFileLength; 0GXO&rCG  
} V'gw\mcb  
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//保存下载信息（文件指针位置）

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private void write_nPos() ,^'R_efY  
{ &h~aChJ  
try{ MXvXVhCU  
output = new DataOutputStream(new FileOutputStream(tmpFile)); B]iP't\~  
output.writeInt(nStartPos.length); 0E/:|k  
for(int i=0;i<nStartPos.length;i++) _|{aC1Y!V  
{ k9si|'  
// output.writeLong(nPos); e [0w5)X   
output.writeLong(fileSplitterFetch.nStartPos); Ff4*IOZ}(  
output.writeLong(fileSplitterFetch.nEndPos); j tA*pL'/V  
} Q(@IK&v  
output.close(); D!LX?_cD1i  
} 9
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catch(IOException e){e.printStackTrace ();} wz /
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catch(Exception e){e.printStackTrace ();} P=8>c'Q  
} F?4(5 K  
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//读取保存的下载信息（文件指针位置） xF
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private void read_nPos() mZvG|P$}  
{ TH1B#Y#<J  
try{ {rH9grb  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); GG6%bF  
int nCount = input.readInt(); *OTS'W~t  
nStartPos = new long[nCount]; S"2qJ!.u  
nEndPos = new long[nCount]; 6`H.%zM  
for(int i=0;i<nStartPos.length;i++) xi
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{ ^4$'KIq  
nStartPos = input.readLong(); cPF<D$B  
nEndPos = input.readLong(); ;[0&G6g  
} C2F
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input.close(); ~oD8Rnf  
} oduDA:  
catch(IOException e){e.printStackTrace ();} rAq
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catch(Exception e){e.printStackTrace ();} &eZfQ2
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} 1cJsj  
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private void processErrorCode(int nErrorCode) V64L,u#`
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{ Zm TDQ`Ix  
System.err.println("Error Code : " + nErrorCode); ^y_fRP~  
} `sHuM*  
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//停止文件下载 ]Y
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public void siteStop() t-e5ld~a  
{ |;vi*u  
bStop = true; Sfjje4R  
for(int i=0;i<nStartPos.length;i++) '\DSTr:N  
fileSplitterFetch.splitterStop(); HeN~c<NuB  
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} \ZXLX'-  
} ,TC;{ $O5  
//负责部分文件的抓取 x8#ODuH  
**FileSplitterFetch.java rP=sG;d  
*/ 773/#c  
package NetFox; +Ezgn/bS&  
5F $V`kYT  
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import java.io.*; QBJ3iQs1  
import java.net.*; _%@=Uc6V  
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public class FileSplitterFetch extends Thread { y}2F9=  
g[z.*y/  
 -7]Xjb5  
String sURL; //File URL :VA.QrKW  
long nStartPos; //File Snippet Start Position H:{7X1bV  
long nEndPos; //File Snippet End Position Xh+ia#K  
int nThreadID; //Thread's ID hZ\+FOx;  
boolean bDownOver = false; //Downing is over 8nNsrat  
boolean bStop = false; //Stop identical QL7
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FileAccessI fileAccessI = null; //File Access interface Hgc=M  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException F phDF  
{ }E^S]hdvz  
this.sURL = sURL; X=X\F@V:u  
this.nStartPos = nStart; B0UJq./`  
this.nEndPos = nEnd; ZXb0Y2AVx  
nThreadID = id; 76fIC  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 L#h:*U{@40  
} vR7HF*8  
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w
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public void run() ~4,I7c7  
{ ><?BqRm+  
while(nStartPos < nEndPos && !bStop) `m~syKz4A  
{ V`hu,Y;%  
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try{ x2VBm$>  
URL url = new URL(sURL); WgR4Ix^L#  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); *<V^2z$y_  
httpConnection.setRequestProperty("User-Agent","NetFox");  3yS  
String sProperty = "bytes="+nStartPos+"-"; TW&DFKK`  
httpConnection.setRequestProperty("RANGE",sProperty); JN3cg  
Utility.log(sProperty); ``Q2P%  
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InputStream input = httpConnection.getInputStream(); *e"a0  
//logResponseHead(httpConnection); cd@.zg'sYn  
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byte[] b = new byte[1024]; !mfJpJ  
int nRead; dx_6X!=.J  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) eARk QV  
{ ZDLMMXx>  
nStartPos += fileAccessI.write(b,0,nRead); Bd0eC#UGkQ  
//if(nThreadID == 1) ;^k7zNf-  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); o,Z{ w"  
} *iXe^<6v  
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7hNb/O004  
Utility.log("Thread " + nThreadID + " is over!"); /L=(^k=a.;  
bDownOver = true; 3HV%4nZLf  
//nPos = fileAccessI.write (b,0,nRead); yYJY;".H  
} Al"3 kRJJ  
catch(Exception e){e.printStackTrace ();} 9|r* pK[  
} MLVB^<qkeH  
} ,8Iv9M}2  
m 40m<@  
6)RbPPeE  
//打印回应的头信息 >O9sk  
public void logResponseHead(HttpURLConnection con) &rq{v!=7  
{ i\}:hU-U  
for(int i=1;;i++) iAO5"(>}?  
{ `|e!Kq?#Q  
String header=con.getHeaderFieldKey(i); IfdI|ya  
if(header!=null) d 4{FDqto  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); BuQ|
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Utility.log(header+" : "+con.getHeaderField(header)); h#YD~!aJ  
else ^y.
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break; KpZ:Nh$  
} JyBp-ii  
} FVWfDQ$&v  
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public void splitterStop() 'JmBh@A  
{ qojXrSb"y  
bStop = true; ^J=hrYGA  
} 6o&ZIYJ9k  
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} {[G`Z9]z&-  
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(
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/* @M;(K<%h  
**FileAccess.java [uuj?Rbd
 
*//文件访问(定位，写) s'I)A^i+  
package NetFox; :Hy]  
import java.io.*; n~0z_;5  
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/="HqBI#i  
public class FileAccessI implements Serializable{ D9ufoa&ua  
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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 a=]Wzlz
 
RandomAccessFile oSavedFile; LgqGVh3\s  
long nPos; 3!9Z=-tD  
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public FileAccessI() throws IOException F3E[wdT  
{ Gm8E<iTP  
this("",0); Q s(Bnb;  
} 9(1rh9`=  
#*$p-I=  
 !rL<5L  
public FileAccessI(String sName,long nPos) throws IOException kE
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{ %CH6lY=lI  
oSavedFile = new RandomAccessFile(sName,"rw"); ]?l{j  
this.nPos = nPos; O12Q8Oj!0  
oSavedFile.seek(nPos); C0C0GqN,  
} H'g?llh1J  
4cgIEw[6  
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public synchronized int write(byte[] b,int nStart,int nLen) ROAI9sW0  
{ 4*H"Z(HP  
int n = -1; >%%=0!,yX  
try{ X T>('qy  
oSavedFile.write(b,nStart,nLen); }uO5q42  
n = nLen; Iin#Wd-/  
} b{[*N  
catch(IOException e) 4SVW/Zl.?  
{ yyl#{Nl@t  
e.printStackTrace (); Q
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} Cnh|D^{s  
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return n; HCnf2td  
} F9o6V|v  
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} e-6w8*!i  
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/* W4(?HTWZ  
**SiteInfoBean.java C8b''9t.  
*/ ?[1SiJT  
package NetFox; +oy*Kxs7  
;Rnhe_A.  
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public class SiteInfoBean { BSUPS+@+  
.XH8YT42  
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private String sSiteURL; //Site's URL vgG}d8MW37  
private String sFilePath; //Saved File's Path wyQb5n2`;~  
private String sFileName; //Saved File's Name EA0iYzV  
private int nSplitter; //Count of Splited Downloading File K
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x7ATI[b[  
public SiteInfoBean() ?Myh7  
{//nSplitter的缺省值为5 @)0 Y~A )  
//default value of nSplitter is 5 %v=!'?VT  
this("","","",5); F@SG((`  
} 9YKDguG  
kK[duW=6  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) mnQ'X-q3iO  
{ 4F#%f#"  
sSiteURL= sURL; R}%8s*  
sFilePath = sPath; :t$A8+A+0  
sFileName = sName; {8CWWfHCD  
this.nSplitter = nSpiltter; &=w|vB)(p  
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} PdE>@0X?M  
7'j9rmTXs  
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public String getSSiteURL() esq<xuZM4  
{ 6Z
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return sSiteURL; lo:~aJ8  
} Q"}s>]k3_  
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19I:%$U3  
public void setSSiteURL(String value) ^Q2ZqAf^a  
{ -u6#-}S
  
sSiteURL = value; /bcY6b=:  
} ixI:@#5wY  
@YZ 4AC  

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public String getSFilePath() +TX/g~  
{
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return sFilePath; >>V&yJ_  
} > V%Q O>C  
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<94WZ?{p  
public void setSFilePath(String value) |5ONFde"0  
{ FdxsUDL  
sFilePath = value; [x_s/"Md;  
} otq,R6 ^  
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$9H[3OZPVv  
public String getSFileName() jT^!J+?6K+  
{ Bl4 dhBZoO  
return sFileName; fN[n>%)VO<  
} {j@+h%sF>+  
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public void setSFileName(String value) 
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{ #s^s_8#&e  
sFileName = value; cjT[P"5$  
} sp{j!NSL  
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Lz6*H1~  
public int getNSplitter() .mt^m   
{ }su6izx  
return nSplitter; s=/^lOOO  
} Q\WXi  
ZKQo#!}  
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public void setNSplitter(int nCount) ZR mPP  
{ ?!m ma\W  
nSplitter = nCount; t|=n1\=?  
} 2IzfP;V?  
} $jcz?vH  
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;tr)=)q&  
/* Oga1u  
**Utility.java ,\>g  
*/ ua:9`+Dff  
package NetFox; 88YC0!Ni  
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public class Utility { ^0eO\wc?O  
-
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public Utility() /&6Q)  
{ y4r2}8fi  
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+{^'i P  
} $w`veP  
B3.X}ys#  
//线程睡眠 `&,
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public static void sleep(int nSecond) /J.0s0@  
{ H<z30r/-w  
try{ Di])<V  
Thread.sleep(nSecond); pLo;#e8'f  
} m9I(TOw  
catch(Exception e) f~iML5lG  
{ 1O4D+0@  
e.printStackTrace (); Vy r] x  
} w'XSb.\)_m  
} x{j+}'9  
T7s+9CE  
//日志 2_I+mQ  
public static void log(String sMsg) -G!6
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{ o[imNy~~  
System.err.println(sMsg); 4V>vg2 d  
} K"I{\/x@  
lXw;|dGF  
vhX-Qkt}  
public static void log(int sMsg) 1"d\
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{
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System.err.println(sMsg); w4aiI2KFq  
} Uv'uqt  
} 9QZ}Hn`p  
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/* sB8p( L  
**TestMethod.java %'kX"}N/  
*/ epYj+T  
package NetFox; sI4QI\*4  
wNbTM.@  
i(z+a6^@|  
public class TestMethod { iPz1eUj  
R'r|E_  
R rxRa[{Z  
public TestMethod() ^|r`"gOJ3  
{ ///xx/weblogic60b2_win.exe zQ=aey%  
try{ t3K>\ :  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); <w;D$l}u  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); L#[HnsLp_  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 65uZLsQ  
fileFetch.start(); P mC82"  
} VBhE{4J  
catch(Exception e){e.printStackTrace ();} ?3n=m%W,J*  
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2,+@#q  
} rdFs?hO  
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public static void main(String[] args) (tTLK0V-|3  
{ e1oFnu2R  
new TestMethod(); )!BB/'DRQ  
} KqFmFcf|  
} _AVy:~/  
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