http断点续传简单实现（java)

/* H]]UsY`  
**SiteFileFetch.java Z]L_{=*  
*/ C1V:_-  
package NetFox; (i3V  
import java.io.*; ]IF QD  
import java.net.*; R
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public class SiteFileFetch extends Thread { :eHD{=  
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SiteInfoBean siteInfoBean = null; //文件信息Bean *yx5G-#?  
long[] nStartPos; //开始位置 YJ6y]r K2,  
long[] nEndPos; //结束位置 v3zd>fDnRp  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Z
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long nFileLength; //文件长度 vw.rkAGY  
boolean bFirst = true; //是否第一次取文件 oc|%|pmRd<  
boolean bStop = false; //停止标志 .$o0$`}  
File tmpFile; //文件下载的临时信息 %R?B=W7;Q  
DataOutputStream output; //输出到文件的输出流 K[,d9j`^  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） adCT
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public SiteFileFetch(SiteInfoBean bean) throws IOException "c+j2f'f  
{ jRn5)u  
siteInfoBean = bean; DHI%R<  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); N*^iOm]Y  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ?$chO|QY  
if(tmpFile.exists ()) kU75  
{ rnOg;|u8  
bFirst = false; vk:k~  
read_nPos(); YGdzA]3>  
} ^-wdIu~p?  
else Xa
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{ r%:Q(|v?  
nStartPos = new long[bean.getNSplitter()]; X=1Po|  
nEndPos = new long[bean.getNSplitter()]; s%cfJe_k  
} / 5\gP//9K  
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} `/e EdqT  
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public void run() tf
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{ LMGo8%2I  
//获得文件长度 Q<c{$o  
//分割文件 SlaHhq3  
//实例FileSplitterFetch pYRqV  
//启动FileSplitterFetch线程 `d,v  
//等待子线程返回 *UerLpf  
try{ W{El^')F  
if(bFirst) ^Rpy5/d  
{ 4uX|2nJ2!;  
nFileLength = getFileSize(); 8\lRP,-  
if(nFileLength == -1) mJ #|~I*Z-  
{  /#FU"  
System.err.println("File Length is not known!"); NMy+=GZu^  
} mm1fG4 *%  
else if(nFileLength == -2) H^d2|E[D  
{ $n><p>`  
System.err.println("File is not access!"); }G/#Nb)  
} )%zOq:{\5  
else [^D~T  
{ #F^0uUjq  
for(int i=0;i<nStartPos.length;i++) sC}p_'L  
{ 78MQoG<  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); v1j&oA}$.  
} >N bb0T  
for(int i=0;i<nEndPos.length-1;i++) o5(~nQ  
{ i"_@iN0N  
nEndPos = nStartPos[i+1]; \@8.BCWK  
} K*/X{3J;  
nEndPos[nEndPos.length-1] = nFileLength; c/'Cju W  
} Iq?#kV9)  
} qlU"v)Mx  
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//启动子线程 =i1+t"
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; a5dc#f Kf  
for(int i=0;i<nStartPos.length;i++) o0)k5P~<~  
{ Lu.C+zgQ  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), @ L=dcO{r  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), K2o\+t  
nStartPos,nEndPos,i); US'rhSV  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Chs#}=gzi  
fileSplitterFetch.start(); w9aLTLv-  
} B)`@E4i  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), N?3BzI%?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); AzZb0wW6p  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", q(XO_1W0V  
nEndPos = " + nFileLength); oro^'#ki  
// fileSplitterFetch[nPos.length-1].start(); DkA@KS1Dq  
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n# 4e1n+I  
//等待子线程结束 `Ei:Z%@7C  
//int count = 0; - %'ys  
//是否结束while循环 F8pP(Wl  
boolean breakWhile = false; .l:x!  
=U`9_]~1c@  
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while(!bStop) 84f~.45  
{ 0_f6Qrcj  
write_nPos();  N3m~nEj  
Utility.sleep(500); "Nh}_jO  
breakWhile = true; )KbzgmLr  
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for(int i=0;i<nStartPos.length;i++) >"|"Gy (  
{ ^fqco9^;  
if(!fileSplitterFetch.bDownOver) y{#9&ct&  
{ \\(3gB.Gd  
breakWhile = false; B.Y8O^rx  
break; YcdT/
  
} _0Z8V[  
} [9H986=  
if(breakWhile) d8Sr,t+  
break; y3Q2d7G  
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//count++; qZB}}pM#  
//if(count>4) grZ?F~P8  
// siteStop();
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} gCP f1z  

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System.err.println("文件下载结束！"); zy\R>4i'#Q  
} 7f_tH_(  
catch(Exception e){e.printStackTrace ();} mIYM+2p  
} (&@,ZI;  
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//获得文件长度 @E !`:/k
 
public long getFileSize() Hq!|(  
{ j1i<.,0g  
int nFileLength = -1; &Ndq^!e  
try{ d3&l!DoX  
URL url = new URL(siteInfoBean.getSSiteURL()); kNC]q,ljt5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); aQ#6PO7.Z  
httpConnection.setRequestProperty("User-Agent","NetFox"); {Q/_I@m].  
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int responseCode=httpConnection.getResponseCode(); i"GCm`  
if(responseCode>=400) 9*CJWS;  
{ yr[HuwU  
processErrorCode(responseCode); 3aERfIJyE  
return -2; //-2 represent access is error C|g]Y 7  
} Jj'dg6QY'  
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String sHeader; ?5Q_G1H&  
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for(int i=1;;i++) Xd@_:ds  
{ )o N#%%SB<  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); *$*V#,V-  
//Utility.log(in.readLine()); b3^d!#KVM  
sHeader=httpConnection.getHeaderFieldKey(i); )D8V;g(7F  
if(sHeader!=null) <wj}y0(  
{ QQW]j;'~  
if(sHeader.equals("Content-Length")) oeF0t'%  
{ ~Bls
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ~7O.}RP0  
break; g"|/^G_6S  
} 4)z*Vux  
} %WO4uOi:@  
else #4wia%}u  
break; ]]!&>tOlI  
} !Jk|ha~r  
} Wo,"$Z6B  
catch(IOException e){e.printStackTrace ();} y%@C-:
 
catch(Exception e){e.printStackTrace ();} ;pVnBi  
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Utility.log(nFileLength); Cw,;>>Y_b<  
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return nFileLength; *]+5T-R% $  
} rpMjDjW  
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yl UkVr   
//保存下载信息（文件指针位置） }e8u p*#me  
private void write_nPos() l<dtc[  
{ JzZ@Z8%a;  
try{ =b/:rSd$NA  
output = new DataOutputStream(new FileOutputStream(tmpFile)); y2
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output.writeInt(nStartPos.length); ^7-l<R[T  
for(int i=0;i<nStartPos.length;i++) @*"H{xo.U  
{ QvvH/u  
// output.writeLong(nPos); V)#rP?Y  
output.writeLong(fileSplitterFetch.nStartPos); L3|~ i&k  
output.writeLong(fileSplitterFetch.nEndPos); I*OJPFZ^4  
} m={TBV,L  
output.close(); Fh U*mAX)  
} ty-erdsP  
catch(IOException e){e.printStackTrace ();} zOsk'ZE&  
catch(Exception e){e.printStackTrace ();} DWmViuZmL  
} Tt+E?C%Y  
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//读取保存的下载信息（文件指针位置） 2x<4&^  
private void read_nPos() M#o'hc  
{ F_z1ey`t  
try{ ,!Q^"aOT:  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); l#^weXSlk  
int nCount = input.readInt(); \R
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nStartPos = new long[nCount]; ! w2BD^V-  
nEndPos = new long[nCount]; Z;[f,Oj  
for(int i=0;i<nStartPos.length;i++) Ew>lk9La(  
{ >A ?{cbJ  
nStartPos = input.readLong(); #{x4s?  
nEndPos = input.readLong(); 84jA)  
} M\6u4p!G!  
input.close(); L{uQ:;w1  
} hjx=?  
catch(IOException e){e.printStackTrace ();} 1/<Z6 ?U  
catch(Exception e){e.printStackTrace ();} rUWC=?Q  
} Wj"GS!5  
Vk?US&1q}  
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private void processErrorCode(int nErrorCode) *Vr;rk  
{ hYY-Eq4TC  
System.err.println("Error Code : " + nErrorCode); 7?a!x$-U(  
} q~G@S2=}0}  
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//停止文件下载 RC+`sZE9  
public void siteStop() _&}z+(Ug  
{ ]B=2r^fn  
bStop = true; 8c5%~}kG  
for(int i=0;i<nStartPos.length;i++) |jJ9dTD8/  
fileSplitterFetch.splitterStop(); R/@n+tbe  
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} W}rLHAaDh  
} B(qwTz 51  
//负责部分文件的抓取 yYn7y1B  
**FileSplitterFetch.java =At)
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*/ c'&\[b(m  
package NetFox; #B&%Y6E5  
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#S') i1;  
import java.io.*; U2kl-E:  
import java.net.*; h7cE"m  
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public class FileSplitterFetch extends Thread { Tv /?-`Y  
8Q\ T,C  
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String sURL; //File URL 8Y&_X0T|  
long nStartPos; //File Snippet Start Position "d c- !  
long nEndPos; //File Snippet End Position pu,|_N[xq8  
int nThreadID; //Thread's ID uL9O_a;!  
boolean bDownOver = false; //Downing is over Pe)SugCs  
boolean bStop = false; //Stop identical t)^18 z  
FileAccessI fileAccessI = null; //File Access interface . E?a  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 9MUg/  
{ p n(y4we  
this.sURL = sURL; 3"p'WZ>  
this.nStartPos = nStart; 4
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this.nEndPos = nEnd; $ nHf0.V
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nThreadID = id; t2RL|$>F1  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 hd~0qK  
} bguTWI8bk  
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public void run() W:V.
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{ rhj_cw  
while(nStartPos < nEndPos && !bStop) e(Y5OTus  
{ a}5/?/  
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try{ zp:EssO=Q  
URL url = new URL(sURL); <(W:Q3?s  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); xY<*:&  
httpConnection.setRequestProperty("User-Agent","NetFox"); NEff`mwm5)  
String sProperty = "bytes="+nStartPos+"-"; X^7n/|%*.  
httpConnection.setRequestProperty("RANGE",sProperty); 3eR c>^wh  
Utility.log(sProperty); VX]Ud\(  
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InputStream input = httpConnection.getInputStream(); `=19iAp.  
//logResponseHead(httpConnection); zr^"zcfz&  
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byte[] b = new byte[1024]; ;(Kj-,>  
int nRead; DQ9}('^  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ^C70b)68  
{ mae@L  
nStartPos += fileAccessI.write(b,0,nRead); Ob@HzXH  
//if(nThreadID == 1) n7(/ml+Q_  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?#Y1E~N  
} u -A_l<K
 
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Utility.log("Thread " + nThreadID + " is over!"); P`OZoI$bV  
bDownOver = true; K?eY<L  
//nPos = fileAccessI.write (b,0,nRead); JGQ)/(  
} ,)Z1&J?  
catch(Exception e){e.printStackTrace ();} bEli!N$
  
} #@}wl  
} \vF*n Z5/  
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//打印回应的头信息 [BuAJ930#5  
public void logResponseHead(HttpURLConnection con) Yk=2ld;;  
{ O[15xH,  
for(int i=1;;i++) LjPpnjU  
{ YWhp4`m  
String header=con.getHeaderFieldKey(i); 'Oa(]Br[  
if(header!=null) I;+>@Cn(g<  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); k@^T<Ci  
Utility.log(header+" : "+con.getHeaderField(header)); 
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else DH!_UV  
break; *  \%b1  
} 8Dc
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} _`+2e-  
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*_/n$& I%&  
public void splitterStop() F~wqt7*  
{ Pv3qN{265  
bStop = true; $aDk
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} y4Lh
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2!?=I'uMA  
]+d>;
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} 'pC51}[A{^  
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 wkKSL  
/* 51Q~/  
**FileAccess.java xbD]EC  
*//文件访问(定位，写) g]jCR*]  
package NetFox; g<^-[w4/  
import java.io.*; ->`R[k  
,$bK)|pGV  
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public class FileAccessI implements Serializable{ X.[8L^ldh  
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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 HiSNEp$-4$  
RandomAccessFile oSavedFile; .05x=28n%  
long nPos; <b_?[%(u  
lt& c/xi_  
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public FileAccessI() throws IOException BQL](Y"  
{ 0`Y"xN`'i  
this("",0); @o>3 Bv.  
} V?-SvQIk1  
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public FileAccessI(String sName,long nPos) throws IOException X1o=rT  
{ 5#Et.P'  
oSavedFile = new RandomAccessFile(sName,"rw"); RKb (  
this.nPos = nPos; |vgYi  
oSavedFile.seek(nPos); PH>`//D%n?  
} Qq3UC%Z1  
I
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{QVs[ J1  
public synchronized int write(byte[] b,int nStart,int nLen)  >f*Zf(F  
{ .svlJSx  
int n = -1; EM!9_8 f  
try{ >r.W \  
oSavedFile.write(b,nStart,nLen); VF:95F;@  
n = nLen; 0X4I-xx#  
} w3jcit|  
catch(IOException e) XPT@ LM  
{ m.ejGm?  
e.printStackTrace (); =DwY-Ex  
} }Apn.DYbbf  
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return n; g)nT]+&  
} 3c[]P2Bh  
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} b)7v-1N  
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/* *{dMo,.eI  
**SiteInfoBean.java mT,#"k8  
*/ t(p}0}Pp  
package NetFox; V z-]H]MW,  
[}`-KpV!;  
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public class SiteInfoBean { >\[|c  
2#R8}\  
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private String sSiteURL; //Site's URL 3u[5T|D'  
private String sFilePath; //Saved File's Path
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private String sFileName; //Saved File's Name rY295Q  
private int nSplitter; //Count of Splited Downloading File \nU_UH  
a LJ d1Q
 
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public SiteInfoBean() <jG[ z69)  
{//nSplitter的缺省值为5 ["sm
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//default value of nSplitter is 5 \{;3'<  
this("","","",5); Q-Oj%w
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} [wn! <#~v  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Q:8t1ZDo  
{ W{fNZb'  
sSiteURL= sURL; 5=/j  
sFilePath = sPath; Fil6;R  
sFileName = sName; 6mV^akapv  
this.nSplitter = nSpiltter; #3_ @aq*  
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} pyp0SGCM:  
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public String getSSiteURL() kY{;(
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{ KO[,C[;|j  
return sSiteURL; \`R8s_S  
} Fb6d1I^wR  
#~[{*[B+  
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public void setSSiteURL(String value) xB5QM #w\  
{ u,./,:O%=  
sSiteURL = value; s&1
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} v\D.j4%ij  
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public String getSFilePath() :ZadPn56  
{ C4)m4r%  
return sFilePath; {Mc;B9W  
} :Z+Jt=;  
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m  
p\DSFB  
public void setSFilePath(String value) 4@QR2K|  
{ <[?ZpG  
sFilePath = value; f([d/  
} vF)eo"_s*  
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public String getSFileName() wK0],,RN,h  
{ ~>XqR/v  
return sFileName; |q c<C&O  
} d&naJ)IoF)  
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public void setSFileName(String value) 6pbtE]  
{ kAq#cLprG  
sFileName = value; }8'b}7!  
} ~.CmiG.7  
N
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public int getNSplitter() O bc>f|l]  
{ hGR
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return nSplitter; q4Mv2SPT  
} m .R**g  
0+/ew8~$  
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public void setNSplitter(int nCount) I.it4~]H  
{ %Z*N /nU  
nSplitter = nCount; w<Bw2c  
} z fu)X!t^  
} U:bnX51D4  
)FN$Jlo  
E6zPN?\ <  
/* D#gC-,  
**Utility.java klnk{R.>|  
*/ S|F:[(WaM  
package NetFox; 6zI}?KZf
 
/7x1Z*Hg  
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public class Utility { <`WcI`IAb  
d>V#?1$h  
F
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public Utility() 3Hi8=*  
{ + ]iK^y-.r  
}ld^zyL  
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} LCW}1H:Q  
&Bqu2^^  
//线程睡眠  HlEHk'  
public static void sleep(int nSecond) [Y.=bfV!  
{ J,\e@  
try{ M0$E_*  
Thread.sleep(nSecond); FH%M5RD  
} z\$(@:{A  
catch(Exception e) )y{:Uc\4!  
{ tG~[E,/`  
e.printStackTrace (); #H
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} <h~=d("j  
} 3,n"d-  
kn/xt  
//日志 f~7V<v  
public static void log(String sMsg) !t}yoN n|  
{ Z\cD98B#
 
System.err.println(sMsg); ]r'D  
} M3r;Pdj2r  
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eD7qc1*G  
public static void log(int sMsg) P3nBxw"  
{ rAE5.Q!u  
System.err.println(sMsg); |a%Wd  
} hzT)5'_  
} F|@\IVEB]  
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-hc8IS
 
/* v0?SN>fZ  
**TestMethod.java vmh>|N4a7  
*/ h1l%\3ZH  
package NetFox; &x;n^W;#  
>P]gjYN  
xsiJI1/68  
public class TestMethod { <@Vf:`a!P>  
J4@-?xj=\q  
zQ#*O'-n  
public TestMethod() I?^(j;QpS  
{ ///xx/weblogic60b2_win.exe .h\Py[h<^  
try{ |>Fz:b d  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); V7.g,  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); u:mndTpB6x  
SiteFileFetch fileFetch = new SiteFileFetch(bean); M93*"jA  
fileFetch.start(); G4&?O_\;  
} #2Iag'4T  
catch(Exception e){e.printStackTrace ();} SPXvi0Jg  
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} g> ~+M  
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public static void main(String[] args) Y B,c=Wx  
{ kW1w;}n$  
new TestMethod(); @_7rd  
} Hp>L}5 y[  
} `- (<Q;iO  
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