http断点续传简单实现（java)

/* cO\-  
**SiteFileFetch.java 3;7q`  
*/ dL
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package NetFox; < AI;6/  
import java.io.*; )-Ej5'iHr  
import java.net.*; X53mzs  
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public class SiteFileFetch extends Thread { Q \]Xm>  
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SiteInfoBean siteInfoBean = null; //文件信息Bean -ZW3  
long[] nStartPos; //开始位置 .c^ ggy%  
long[] nEndPos; //结束位置 l;"Ab?P\  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 tu>{  
long nFileLength; //文件长度 iB1i/l  
boolean bFirst = true; //是否第一次取文件 RGIoI]_  
boolean bStop = false; //停止标志 BPqGJ7@  
File tmpFile; //文件下载的临时信息 [U8$HQ+x  
DataOutputStream output; //输出到文件的输出流 1z*kc)=JF8  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） "BKeot[""p  
public SiteFileFetch(SiteInfoBean bean) throws IOException ,&7Wa-vf  
{  :Pq.,s  
siteInfoBean = bean; mmEp'E  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Q}*y$se!  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ]DvO:tM  
if(tmpFile.exists ()) |2`"1gt  
{ H]\Zn%.#  
bFirst = false; joa5|t!D9  
read_nPos(); Q
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} 85|fyX  
else V8-h%|$p3W  
{ 0IT@V5Gdj  
nStartPos = new long[bean.getNSplitter()]; #hL*rbpT  
nEndPos = new long[bean.getNSplitter()]; j2M+]Zp.  
} 2X88:  
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} `Zz uo16  
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public void run() h?UVDzI!O  
{ a :HNg  
//获得文件长度 ;`v% sx#  
//分割文件 }:z5t,u6  
//实例FileSplitterFetch K{cbn1\,H  
//启动FileSplitterFetch线程 cPn+<M#  
//等待子线程返回 !&]z*t  
try{ oc{EuW{Ag  
if(bFirst) [U\
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{ p"`
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nFileLength = getFileSize(); /.V0ag'G  
if(nFileLength == -1) Uh|>Skic4  
{ GZ}/leR  
System.err.println("File Length is not known!"); BRbV7&  
} ohc1 ~?3b  
else if(nFileLength == -2) Bmo
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{ {hqAnZ@]vr  
System.err.println("File is not access!"); :Gh
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} ad n|N  
else \&}G]  
{ jN/C'\QL  
for(int i=0;i<nStartPos.length;i++) Nm]% }  
{ uD>z@J-v  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Az,- C
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} MZ#T^Y  
for(int i=0;i<nEndPos.length-1;i++) \ Aq;Q?  
{ zPZF|%|  
nEndPos = nStartPos[i+1]; TSo:7&|  
} (E($3t8  
nEndPos[nEndPos.length-1] = nFileLength; :WXf.+IA  
} :#="%  
} L>Jd7;=  
r
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u/AT-er;  
//启动子线程 |V`S>m
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Sl~x$9`  
for(int i=0;i<nStartPos.length;i++) X QbNH~  
{ L2-^!'  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), b>cafu  
nStartPos,nEndPos,i); /N^~U&7  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'pP-rdx  
fileSplitterFetch.start(); `1p 8C%  
} tfiqr|z  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $V8vrT#:  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); -!*p*3|03|  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Q e1oT)  
nEndPos = " + nFileLength); D\]&8w6&  
// fileSplitterFetch[nPos.length-1].start(); 5n:71$6[  
,EhVSrh)_4  
X<MpN5%|Wo  
//等待子线程结束 6Dm+'y]l  
//int count = 0; :%_q[}e  
//是否结束while循环 HdQj?f3  
boolean breakWhile = false; Li`hdrO'ii  
]TK=>;&  
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while(!bStop) t]m!ee8*X<  
{ 02 f9 wV  
write_nPos(); TGWdyIk  
Utility.sleep(500); (:$9%,x  
breakWhile = true; EI`vVI  
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for(int i=0;i<nStartPos.length;i++) mf4z?G@6  
{ ` %' z  
if(!fileSplitterFetch.bDownOver) Ao`_",E  
{ b>q6:=((  
breakWhile = false; 6S*zzJ.0K  
break; 6$B'Q30}r  
} LZ&uj{ <  
} b!~TAT&8  
if(breakWhile)  *q"G }  
break; -qn[HXq  
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//count++; #)i&DJ^Y  
//if(count>4) aG3k4  
// siteStop(); f4]&pcK  
} U6i~A9;  
+G!v!(Ob+  

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System.err.println("文件下载结束！"); P06.1  
} (Nt[v;BnO  
catch(Exception e){e.printStackTrace ();} D=w9cKa  
} A#:8X1w  
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$,`VUe{  
//获得文件长度 my[,w$YM  
public long getFileSize() ]N\6h(**wy  
{ $
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int nFileLength = -1; >)%#V<{<  
try{ 7&t~R}&|  
URL url = new URL(siteInfoBean.getSSiteURL()); 'oi2Seq  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); M'|)dM|  
httpConnection.setRequestProperty("User-Agent","NetFox"); 5`UJouHi  
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int responseCode=httpConnection.getResponseCode(); R"Y?iZed3  
if(responseCode>=400) jlRS:$|R0  
{ GEi MmH?  
processErrorCode(responseCode); z\h,SX<U  
return -2; //-2 represent access is error W8uVd zQ  
} %QE5<2k  
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String sHeader; tBTJmih"  
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for(int i=1;;i++) (.oaMA"B  
{ T:)% P6/  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ._K$0U!  
//Utility.log(in.readLine()); hwZ6.  
sHeader=httpConnection.getHeaderFieldKey(i); E~69^cd  
if(sHeader!=null) )ys=+Pz  
{ p9w%kM?  
if(sHeader.equals("Content-Length")) l)iv\j  
{ %30T{n:  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); I W8.  
break; :D^Y?  
} MyM+C}  
} 7n<#y;wo  
else }RDb1~6C  
break; 1[[TB .xF  
} hC|KH}aCR)  
} IKtiR8  
catch(IOException e){e.printStackTrace ();} G#g{3}dcK  
catch(Exception e){e.printStackTrace ();} rkP4<E-M  
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Utility.log(nFileLength); Flne=ij6g  
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return nFileLength; 3P3:F2S R  
} 5@CpP-W#  
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//保存下载信息（文件指针位置） Yo@m50s$  
private void write_nPos() ]zy~@,\  
{ U"/yB8!W  
try{ ,?t}NZY&  
output = new DataOutputStream(new FileOutputStream(tmpFile)); nxf{PbHk  
output.writeInt(nStartPos.length); ;4R=eI  
for(int i=0;i<nStartPos.length;i++) HUD7{6
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{ Y]M^n&f
 
// output.writeLong(nPos); ;*"!:GR%h  
output.writeLong(fileSplitterFetch.nStartPos); ''%;EW>  
output.writeLong(fileSplitterFetch.nEndPos); #efqG=q  
} %h
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output.close(); k>$FT`  
} X9z:D>   
catch(IOException e){e.printStackTrace ();} %e(9-M4*  
catch(Exception e){e.printStackTrace ();} P7cge  
} % i%ew4  
%f>X-*}NI-  
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//读取保存的下载信息（文件指针位置） p"g1V7B  
private void read_nPos() CL EpB2_  
{ )#)
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try{ ;K>{_kf  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); -qs(2^  
int nCount = input.readInt(); d?Ia#K93G  
nStartPos = new long[nCount]; s+(l7xH$  
nEndPos = new long[nCount]; %_]=i@Y~  
for(int i=0;i<nStartPos.length;i++) 3$MYS^D  
{ YG-Z.{d5Z  
nStartPos = input.readLong(); 9"[!EKW  
nEndPos = input.readLong(); wxH(&CB-{  
} -B<O_*wOj  
input.close(); DN4fP-m-  
} E~rs11  
catch(IOException e){e.printStackTrace ();} :5$xh  
catch(Exception e){e.printStackTrace ();} )[e%wPu4e  
} ZTN:|IKT  
2]?w~qjWm  
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private void processErrorCode(int nErrorCode) ._8xY$l$  
{ dM$N1DB{U+  
System.err.println("Error Code : " + nErrorCode); bbfDt^  
} N |OMj%Uk  
7KvXTrN!9  
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//停止文件下载 bEVO<x+  
public void siteStop() '*o7_Ez-{  
{ bd@*vu}?}  
bStop = true; %s~NQ;Y  
for(int i=0;i<nStartPos.length;i++) N1D6
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fileSplitterFetch.splitterStop(); ORV}j,Ym  
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} 3bT6W,J4T  
} [0mFy)6  
//负责部分文件的抓取 ;zfQ3$@9  
**FileSplitterFetch.java < fojX\}3  
*/ N
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package NetFox; O;"*_Xq(`  
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import java.io.*; #i`A4D  
import java.net.*; %igFHh?  
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public class FileSplitterFetch extends Thread { .g6PrhzFbk  
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String sURL; //File URL h,!G7V  
long nStartPos; //File Snippet Start Position >N+bU{s  
long nEndPos; //File Snippet End Position e>])m3xvn  
int nThreadID; //Thread's ID rW=k%# p  
boolean bDownOver = false; //Downing is over hQd@bN8  
boolean bStop = false; //Stop identical 1q}u?7nnSG  
FileAccessI fileAccessI = null; //File Access interface 3{2^G@j  
@%I_&!d  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException zIAu3  
{ E
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this.sURL = sURL;
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this.nStartPos = nStart; = )JVT$]w  
this.nEndPos = nEnd; yr/]xc$  
nThreadID = id; Rye~w6  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 O<eWq]  
} ~$?y1Yv  
4~MJ4:  
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public void run() Yj^avO=;  
{ 1sIy*z  
while(nStartPos < nEndPos && !bStop) QK``tWLIg7  
{ &;~2sEo,  
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try{ ei+
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URL url = new URL(sURL); Tc'{i#%9j  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #f|NM7  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'XZI{q2i  
String sProperty = "bytes="+nStartPos+"-"; y(bt56 | z  
httpConnection.setRequestProperty("RANGE",sProperty); hX>VVeIZ  
Utility.log(sProperty); ${E[pT  
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InputStream input = httpConnection.getInputStream(); Q+u#?['  
//logResponseHead(httpConnection); k *G!.  
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byte[] b = new byte[1024]; g "K#&  
int nRead; ~7,2N.vO2  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) azR;*j8Q'  
{ QKUBh-QFK  
nStartPos += fileAccessI.write(b,0,nRead); uK4'n+_>\  
//if(nThreadID == 1) O$<%z[  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @~!-a s7  
} |&0"N[t  
.%J?T5D  
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Utility.log("Thread " + nThreadID + " is over!"); T~wZ  
bDownOver = true; I\Gp9w0
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//nPos = fileAccessI.write (b,0,nRead); },Re5W nl  
} 3j=%De  
catch(Exception e){e.printStackTrace ();} \CJx=[3(  
} bCE7hutl  
} M0Kh>u  
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//打印回应的头信息 *1o+o$hY2  
public void logResponseHead(HttpURLConnection con) :EQme0OW  
{ dm/\uE'l  
for(int i=1;;i++) Hl3XqR  
{
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String header=con.getHeaderFieldKey(i); +GYI2  
if(header!=null) k8x&aH  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); d=4f`q0k  
Utility.log(header+" : "+con.getHeaderField(header)); 8~[C'+r  
else uJ)=+Exii
 
break; f9l<$l  
} o {XwLi  
} VM2@{V/=~  
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public void splitterStop() $cJN9|$6  
{ avxn}*:X.  
bStop = true; $)T
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} ExOB P  
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} Io4:$w  
f5=t*9_-[  
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/* T956L'.+G  
**FileAccess.java (/x@W`  
*//文件访问(定位，写) 4_m /_Z0x  
package NetFox; ]|$$:e^U9  
import java.io.*; Z1V'NJI+  
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public class FileAccessI implements Serializable{ "{ QHWZ  
Nh\8+v*+{  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 DKVt8/vq  
RandomAccessFile oSavedFile; {DXZ}7w:v  
long nPos; yu?
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public FileAccessI() throws IOException &zh+:TRm  
{ M9 2~iM  
this("",0); J! 6z  
} |b-Zy~6  
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#HnyE+tD  
public FileAccessI(String sName,long nPos) throws IOException zIQc#F6\5  
{ im?XXsH'  
oSavedFile = new RandomAccessFile(sName,"rw"); xu?QK6D:  
this.nPos = nPos; [A..<[  
oSavedFile.seek(nPos); |phWK
^  
} (Y.$wMB  
uQ%HLL-W/  
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public synchronized int write(byte[] b,int nStart,int nLen) GY$?^&OO>  
{ <9k}CXv2PK  
int n = -1; kzVI:  
try{ U_{JM`JY  
oSavedFile.write(b,nStart,nLen); ge {4;,0=  
n = nLen; etK,zEd  
} *ckrn>E{h  
catch(IOException e) t`1]U4s&I  
{ K7O?{/  
e.printStackTrace (); -R$FJbId  
} ah Xq{>  
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return n; 4^NHf|UJH  
} "0 PN  
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} sV'.Bomq  
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,/b/O4`;y  
/* N evvA(M  
**SiteInfoBean.java XsN#<"f;i  
*/ ccR
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package NetFox; 4%v+ark8  
T17LYHIT  
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public class SiteInfoBean { 
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:kx#];2i  
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private String sSiteURL; //Site's URL Mjvso0zj  
private String sFilePath; //Saved File's Path zT-"kK  
private String sFileName; //Saved File's Name Okg8Ve2  
private int nSplitter; //Count of Splited Downloading File Y6Qb_X:  
,sJfMY  
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public SiteInfoBean() Rw{v"n  
{//nSplitter的缺省值为5 !BikF4Y1L&  
//default value of nSplitter is 5 ?.A/E?Oc  
this("","","",5); 'MQGR@*  
} GK+\-U)v  
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g  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) P_g0G#`4  
{ T\s#-f[x  
sSiteURL= sURL;
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sFilePath = sPath; ^-;Z8M  
sFileName = sName; XXwhs-:o  
this.nSplitter = nSpiltter; '/*c Yv45  
~0'l,  
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} x15t
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r~2@#gTbl  
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public String getSSiteURL() kZ[yv  
{ Ng39D#_
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return sSiteURL; f
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} +;iesULXn  
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public void setSSiteURL(String value) .F3LA6se  
{ %1 ^jd\  
sSiteURL = value; m.a
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} 5a_!&  
l<:E+lU  
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public String getSFilePath() !X <n:J  
{ kpw4Mq@  
return sFilePath; W!B4<'Fjc  
} wP':B AQ4U  
2^ZPO4|  
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public void setSFilePath(String value) &8i{'k,l  
{ 9qy 9  
sFilePath = value; 7CMgvH)O  
} cH-
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n4&j<zAV{  
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public String getSFileName() p2vUt  
{ sx^? Iw,N'  
return sFileName; ;Hr@0f  
} OjEA;;qq  
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knzED~v@(  
public void setSFileName(String value) 7=*k@9  
{ K$GX
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sFileName = value; J+gsmP-_  
} :{uUc  
s(.-bjR  
@N{Ht)1r  
public int getNSplitter() |+~2sbM  
{ q;PzB4#  
return nSplitter; 3D dG$@  
} (3r,PS@Qq@  
:|Nbk58  
>t}D5ah  
public void setNSplitter(int nCount) 4:PP[2?  
{ 3'e 4{  
nSplitter = nCount; <!(n5y_  
} CHw_?#h  
} O~0 1)%  
#p`7gFl  
, tj7'c$0  
/* 0U*"OSpF  
**Utility.java PQ1NQy8  
*/ bK1`a{  
package NetFox;  /?xn  
=I}V PxhE7  
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public class Utility { cGp 6yf  
"a{f? .X.  
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public Utility() rO%+)M$A  
{ G_mu7w  
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*{s
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} X6'&X  
J vsB^F.4  
//线程睡眠 ]m>MB )9  
public static void sleep(int nSecond) N<(`+?  
{ Y,\mrW}K  
try{ (UXB#I~  
Thread.sleep(nSecond); (Fd4Gw<sq  
} io3'h:+9s  
catch(Exception e) K(<P" g(  
{ #7ZBbq3=  
e.printStackTrace (); p<19 Jw<  
} JCfToFB  
} R\amcQ 9  
kl"Cm`b)  
//日志 )d`$2D&iY  
public static void log(String sMsg) !P3|T\|]+  
{ M0 8Y  
System.err.println(sMsg); oU?X"B9  
} W^Y(FUy~  
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!{lb#  
public static void log(int sMsg) d6&t
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{ 9Wrclai  
System.err.println(sMsg); 9<mj@bI$  
} GqxK|G1  
} *?fBmq[j  
@R{&>Q:.  
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/* cfS]C_6d  
**TestMethod.java X5[sw;rk  
*/ T9?_ `h  
package NetFox; 9
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+JG"eh&J"H  
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public class TestMethod { tH(#nx8  
,-kZ5&r  
/WVMT]T6^,  
public TestMethod() t%@pyK  
{ ///xx/weblogic60b2_win.exe ek!N eu>  
try{ E5Jk+6EcMa  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Y))sk-  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); /p"R}&z  
SiteFileFetch fileFetch = new SiteFileFetch(bean); RA/yvr  
fileFetch.start(); r |/9Dn%  
} r+u\
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catch(Exception e){e.printStackTrace ();} h zE)>f  
(5&"Y?#o,  
+Ti@M1A&  
} j"s(?  
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public static void main(String[] args) +Wc[$,vk  
{ 9k&$bC+Q  
new TestMethod(); do7{  
} iSlVe~ef  
} xW~@V)OH  
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