http断点续传简单实现（java)

/* lOB*M!8   
**SiteFileFetch.java PxE0b0eo  
*/ 8$9Q=M  
package NetFox; M uz+j.0  
import java.io.*; nIc:<w]  
import java.net.*; ~0/tU#&  
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public class SiteFileFetch extends Thread { nwSujD  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 3>vSKh1z  
long[] nStartPos; //开始位置 B6qM0QW  
long[] nEndPos; //结束位置 dAg<BK/  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 V}=%/OY?  
long nFileLength; //文件长度 T .#cd1b  
boolean bFirst = true; //是否第一次取文件 *XN|ZGl/  
boolean bStop = false; //停止标志 [=/Yo1:v  
File tmpFile; //文件下载的临时信息 9NzK1V0X  
DataOutputStream output; //输出到文件的输出流 ;6+e!h'1  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Qg9*mlm`  
public SiteFileFetch(SiteInfoBean bean) throws IOException 3%HF"$Gg  
{ ,zXP,(x  
siteInfoBean = bean; q-? k=RX`  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); PH!^ww6  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); (S<Z@y+d  
if(tmpFile.exists ()) kD"BsL*6!  
{ Qk`ykTS!  
bFirst = false; "^gV.  
read_nPos(); hv.33l  
} $
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else %PF:OB6[|  
{ ayGYVYi  
nStartPos = new long[bean.getNSplitter()]; GTYCNi66  
nEndPos = new long[bean.getNSplitter()]; Lvco9 Ak  
} o
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} (g(.gN]  
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public void run() 
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{ x{'3eJ^8  
//获得文件长度 BeR7LV  
//分割文件 AhozrroV  
//实例FileSplitterFetch ,?k0~fuG6  
//启动FileSplitterFetch线程 m%$GiNs}  
//等待子线程返回 0;J#".(KQ  
try{ 8VWkUsOoI  
if(bFirst) "K Or)QD/  
{ S{uKm1a  
nFileLength = getFileSize(); ` @PHV  
if(nFileLength == -1) 40?xu#"  
{ <q}w,XU  
System.err.println("File Length is not known!"); PJ$C$G  
} !\'NBq,  
else if(nFileLength == -2) #saK8; tp  
{ ='rSB.$Ctk  
System.err.println("File is not access!"); 7A,QA5G]C  
} n8K FP  
else S`w_q=-^8  
{ h=a-~= 8  
for(int i=0;i<nStartPos.length;i++) E:7R>.g  
{ mQ$a^28=qR  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); l^~E+F~  
} \jR('5DcB  
for(int i=0;i<nEndPos.length-1;i++) r0Cc0TMdj  
{ r}>q*yx:  
nEndPos = nStartPos[i+1]; Tr\6AN?o  
} BdMmeM2h  
nEndPos[nEndPos.length-1] = nFileLength; V eD<1<  
} 'c[|\M!u  
} DTx!# [  
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//启动子线程 O>vbAIu  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; tMy<MO)Ei  
for(int i=0;i<nStartPos.length;i++) U07G&?/  
{ tJ qd
  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), AiDV4lHr  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), =cP7"\  
nStartPos,nEndPos,i); BH;7CK=7R  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ~ZxFL$<'3  
fileSplitterFetch.start();
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} Sd9%tO9mf  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), (>)f#t[9J  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 7^hwRZJ{  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Y%GIKtP  
nEndPos = " + nFileLength); %C1*`"Jb&  
// fileSplitterFetch[nPos.length-1].start(); .dE2,9{Z  
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//等待子线程结束 {hRM=f7  
//int count = 0; E0lro+'lS  
//是否结束while循环 rzk-_AFR  
boolean breakWhile = false; {y
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while(!bStop) =QG0:z)K<v  
{ 2D vKW%;  
write_nPos(); 'P`L?/_3  
Utility.sleep(500); wI{ED  
breakWhile = true;
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for(int i=0;i<nStartPos.length;i++) +\D?H.P  
{ "Vw;y+F}  
if(!fileSplitterFetch.bDownOver) BIK^<_?+ZU  
{ ;zpSyyp@  
breakWhile = false; 13f@Ox$  
break; _?m%i]~o
 
} 7[/1uI9U8K  
} '*d);{D8  
if(breakWhile) CHGV1X,  
break; xlHC?d0}  
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//count++; ]ysEj3  
//if(count>4) jWE?$r"  
// siteStop(); sfUKH;xC  
} >P_/a,O8  
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System.err.println("文件下载结束！"); ? 3'O  
} W&'[Xj  
catch(Exception e){e.printStackTrace ();} Up*.z\|'y  
} MmL)CT  
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//获得文件长度 up^D9(y\  
public long getFileSize() S+mM S  
{ P)k!#*  
int nFileLength = -1; *y@Xm~ld  
try{ sSdnH_;&  
URL url = new URL(siteInfoBean.getSSiteURL()); c 0/vB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); A])+Pe  
httpConnection.setRequestProperty("User-Agent","NetFox"); (;(P3h  
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int responseCode=httpConnection.getResponseCode(); gq`S`  
if(responseCode>=400) 'G|M_ e  
{ BJ$\Mb##3@  
processErrorCode(responseCode); %@Ow.7zh  
return -2; //-2 represent access is error +T,Yf/^Fn  
} .kT}E5  
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String sHeader; `(Eiu$h6V-  
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for(int i=1;;i++) ]Lz:oV^%  
{ 6.(
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 4IUdlb  
//Utility.log(in.readLine()); %+F%C=GqI  
sHeader=httpConnection.getHeaderFieldKey(i); Yfa`}
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if(sHeader!=null) +yO^,{8SE  
{ dF#`_!4pbf  
if(sHeader.equals("Content-Length")) BJ,D1E  
{ grWmF3c#  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); w /l\p3n  
break; k&dLg5O  
} !STa}wl  
} %jc"s\  
else ROWrkJI>i  
break; E{B8+T:3  
} _=*ph0nu  
} O_bgrXg6x  
catch(IOException e){e.printStackTrace ();} Dqz9NB  
catch(Exception e){e.printStackTrace ();} *F)+- BB  
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5
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Utility.log(nFileLength); vk>EFm8l  
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return nFileLength; /jB0  
} >r8$vQGj  
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//保存下载信息（文件指针位置） 6vL+qOdx  
private void write_nPos() CG397Y^  
{ ]\ DIJ>JZ  
try{ M>m+VsJV  
output = new DataOutputStream(new FileOutputStream(tmpFile)); NBaXfWh  
output.writeInt(nStartPos.length); Ak=|wY{  
for(int i=0;i<nStartPos.length;i++) X`' @G  
{ wrJ:jTh  
// output.writeLong(nPos); <JkmJ/X  
output.writeLong(fileSplitterFetch.nStartPos); PS
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output.writeLong(fileSplitterFetch.nEndPos); 8Vf]K}d  
} 2n3g!M6~  
output.close(); [e.@Yx_}  
} "eOFp\vPr  
catch(IOException e){e.printStackTrace ();} G~$[(Fhk  
catch(Exception e){e.printStackTrace ();} j7u\.xu9  
} E!SxO~  
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//读取保存的下载信息（文件指针位置） \[MQJX,dn  
private void read_nPos() g$a 5  
{ WJJwhr  
try{ L2P#5
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); *s[bq;$  
int nCount = input.readInt(); Sb,lY<=  
nStartPos = new long[nCount]; bxFDB^  
nEndPos = new long[nCount]; 2J0N]`|)  
for(int i=0;i<nStartPos.length;i++) *$/!.e  
{ CgxGvM4  
nStartPos = input.readLong(); UX!)\5-  
nEndPos = input.readLong(); g*a|QBj%  
} cE SSSH!m  
input.close(); ckCb)r_  
} oe,37xa4  
catch(IOException e){e.printStackTrace ();} 2Ysl|xRo  
catch(Exception e){e.printStackTrace ();} ZBcT@hxm  
} yD\[`!sWk  
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private void processErrorCode(int nErrorCode) 6O9?":3;  
{ q(iM=IeiN  
System.err.println("Error Code : " + nErrorCode); ]%I}hjJ  
} Oqy&V&-C  
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//停止文件下载 ZlEH3-Zv  
public void siteStop() rh+2 7"  
{ L,PD4H"8  
bStop = true; lemE/(`a_  
for(int i=0;i<nStartPos.length;i++) KBSO^<7  
fileSplitterFetch.splitterStop(); 9EIOa/*  
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} R[Y{pT,AY  
} L-V+`![{  
//负责部分文件的抓取 cq-UVk"Gl  
**FileSplitterFetch.java ujH ^ML  
*/ G zw $M  
package NetFox; T#:n7$M|?A  
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uU;]/  
import java.io.*; v5Qp[O_  
import java.net.*; #G`UR  
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public class FileSplitterFetch extends Thread { c(5r  
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String sURL; //File URL @Fs2J_v  
long nStartPos; //File Snippet Start Position n$z+g>~N  
long nEndPos; //File Snippet End Position BL?Bl&p(  
int nThreadID; //Thread's ID s+RSAyU  
boolean bDownOver = false; //Downing is over M+ljg&fy  
boolean bStop = false; //Stop identical p%?m|(4f  
FileAccessI fileAccessI = null; //File Access interface co-dq\P  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException F
9\T<  
{ m.0:
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this.sURL = sURL; fO'"UI  
this.nStartPos = nStart; PW)Gd +y  
this.nEndPos = nEnd; GR ^d/  
nThreadID = id; \cKY
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 wr+r J  
} "S ~(|G  
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public void run() IA&NMf;{  
{ 0S}ogU[k  
while(nStartPos < nEndPos && !bStop) :K]&
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{ <{xU.zp'  
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try{ wx2EMr  
URL url = new URL(sURL); ~[H+,+XLY+  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); {~u#.
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httpConnection.setRequestProperty("User-Agent","NetFox"); 0%f
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String sProperty = "bytes="+nStartPos+"-"; 7>sNjOt@M  
httpConnection.setRequestProperty("RANGE",sProperty); rm"C|T4:V  
Utility.log(sProperty); o{n)w6P{R,  
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InputStream input = httpConnection.getInputStream(); qzbpLV|
  
//logResponseHead(httpConnection); :\sz`p?EC  
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byte[] b = new byte[1024]; aUVJ\;V  
int nRead; ^}>Ie03m50  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) v0|[w2Q2  
{ Dx1
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nStartPos += fileAccessI.write(b,0,nRead); F )|0U~  
//if(nThreadID == 1) (^)" qsB  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); B<}0r4T}  
} ~8#Ku,vEy  
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Utility.log("Thread " + nThreadID + " is over!"); vSf ?o\O  
bDownOver = true; _5%NG 3c  
//nPos = fileAccessI.write (b,0,nRead); F4T}HY>nZ  
} w4UaWT1J  
catch(Exception e){e.printStackTrace ();} Q+ tUxa+  
} U.mVz,k3  
} I0v$3BQ4  
.>A`FqV$~+  
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//打印回应的头信息 +dB/SC-^U  
public void logResponseHead(HttpURLConnection con) =!pfgE  
{ g~#HiBgWq[  
for(int i=1;;i++) ZM$}Xy\9  
{ FR%u1fi  
String header=con.getHeaderFieldKey(i); PRo;NE  
if(header!=null) A"$UU6Z4  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Aqp$JM >  
Utility.log(header+" : "+con.getHeaderField(header)); FdZG%N>Z  
else 9f+S-!  
break; Ta0Ln  
} 4PsJs<u  
} 6.|Qyk*  
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public void splitterStop() h
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{ nm3/-Q},  
bStop = true; xdqiogue  
} n@"h^-  
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} #4Z]/D2G  
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/* K;fRDE){  
**FileAccess.java UCv9G/$  
*//文件访问(定位，写) XX@@tzN  
package NetFox; NjL^FqA[  
import java.io.*; `fA|])3T  
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public class FileAccessI implements Serializable{ GNI
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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 >^!qxb-  
RandomAccessFile oSavedFile; x<-n}VK\  
long nPos; equTKM  
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public FileAccessI() throws IOException _r6aLm2n  
{ S9'8rn!_  
this("",0); $cUTe  
} /N'|Vs,X  
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HU='Hk!  
public FileAccessI(String sName,long nPos) throws IOException ZV?~~_9  
{ ==i:*  
oSavedFile = new RandomAccessFile(sName,"rw"); fNkN  
this.nPos = nPos; V6.w=6:`X  
oSavedFile.seek(nPos); Mr8r(LGY  
} ls<7
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'aFjyY?%  
j![;;  
public synchronized int write(byte[] b,int nStart,int nLen) 1E]|>)$  
{ X9lh@`3  
int n = -1; fT&>L  
try{ RkW)B^#  
oSavedFile.write(b,nStart,nLen); /M.@dW7 w  
n = nLen; p%_m
!   
} Ul41RNy)  
catch(IOException e) $d[xSwang  
{ Ki"o0u  
e.printStackTrace (); BWd{xP y  
} PN$vBFjm  
lM<SoC;[  
 YjV-70'  
return n; e=]>TeqG0  
} ]I|3v]6qR  
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-X)KY_Xn@/  
} XehpW}2\  
@7C?]/8#  
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/* FK8GBkQ!  
**SiteInfoBean.java b)5z
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*/ -@wnQ?  
package NetFox; 5tIM@,.I/  
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public class SiteInfoBean { x9c/;Q&m  
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private String sSiteURL; //Site's URL 
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private String sFilePath; //Saved File's Path <}^W9>u<  
private String sFileName; //Saved File's Name C#y[UM5\k;  
private int nSplitter; //Count of Splited Downloading File RuW62QSq  
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public SiteInfoBean() {APsi7HYBr  
{//nSplitter的缺省值为5 Q|^TR__  
//default value of nSplitter is 5 7d7"^M  
this("","","",5); 1b6ox6  
} ~m]sJpW<"  
E27N1J+1  

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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) yWs_Z6b  
{ ~"Pu6-\VT  
sSiteURL= sURL; e@-"B9~   
sFilePath = sPath; ae)0Yu`*G7  
sFileName = sName; ?Q~6\xA  
this.nSplitter = nSpiltter; Pmj]"7Vd[  
BZXP%{njS  
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} >UP{=`  
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>@2l/x8;  
public String getSSiteURL() Dn6k,nVh  
{ s[V$fvW  
return sSiteURL; <By6%<JTn  
} p8>.Q/4  
?D].Za^km  
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public void setSSiteURL(String value) MZ(TST"  
{ q+MV@8w  
sSiteURL = value; M>mk=-l  
} 'wo[iNy[  
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public String getSFilePath() Jl"),;Od  
{ blwdcdh  
return sFilePath; o8:K6y  
} c !$ 8>  
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public void setSFilePath(String value) v;E7UL .w  
{ )C @W_cfMN  
sFilePath = value; 3~e"CKD>  
} G;n'c7BV  
<&7KcvBn"4  
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public String getSFileName() N0@&eX|$i4  
{
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return sFileName; >H@ zP8  
} %!r>]M <  
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public void setSFileName(String value) FuOP+r!H  
{ KzQ\A!qG  
sFileName = value; _YXk,ME!Q  
} ?|8QL9Q"|  
8{5Y%InL  
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public int getNSplitter() vG(Gs=.U  
{ {iP^51fy  
return nSplitter; RVFQ!0 C  
} })V9d  
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public void setNSplitter(int nCount) la ~T)U7  
{ U!:Q|':=h  
nSplitter = nCount; D6iHkD
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} 7$(>Z^ Em  
} 8K
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/* &qki NS  
**Utility.java Z!TLWX"  
*/ `~Eo;'(+^  
package NetFox; Le9^,B@Pb  
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*P_ 3A:_  
public class Utility { DLYk#d: q?  
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public Utility() QE&rpF7l{  
{
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} tBgB>-h(  
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//线程睡眠 od{b]HvgS  
public static void sleep(int nSecond) y]5O45E0
  
{ ;BV1E|j  
try{ j]EeL=H<P  
Thread.sleep(nSecond); a3i4eGT-  
} 2R&msdF
 
catch(Exception e) } h|1H  
{ 5qkG~YO-  
e.printStackTrace (); _94|^  
} /dpEL9K  
} /,'D4s:Gg  
^)&d7cSc  
//日志 75~>[JM  
public static void log(String sMsg) ffK A  
{ x^kV;^ I  
System.err.println(sMsg); 5V&3m@d0aq  
} *TY?*H  

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public static void log(int sMsg) c&.>SR')  
{ V`Z-m-V~1  
System.err.println(sMsg); *.wX9g9\  
} K &m`1f  
} umrfA  
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/* w,dDA2,  
**TestMethod.java xJ>U_Gd  
*/ V3WHp'1  
package NetFox; +]-~UsM  
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H: Rd4dl,  
public class TestMethod { [mKPOg-t  
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public TestMethod() E(Tvj\9  
{ ///xx/weblogic60b2_win.exe JQQP!]%}  
try{ ~=~|@K  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); sf4NKe2*  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); o5dPE{f  
SiteFileFetch fileFetch = new SiteFileFetch(bean); k3::5&  
fileFetch.start(); mGZ^K,)&OR  
} ZI4[v>  
catch(Exception e){e.printStackTrace ();} :@zz5MB5@  
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Md_S};!QN6  
} v'(p."g  
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public static void main(String[] args) Y.&nxT95=  
{ >[;+QVr;  
new TestMethod(); @l:\0cO  
}  L5/J  
} LYb@0O<w  
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