http断点续传简单实现（java)

/* 0p"l}Fu@`  
**SiteFileFetch.java \J*~AT~5q  
*/ (twwDI  
package NetFox; p
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import java.io.*; KxyD{W1  
import java.net.*; oy8L{8?  
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public class SiteFileFetch extends Thread { Wpgp YcPS  
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SiteInfoBean siteInfoBean = null; //文件信息Bean KIY/nu   
long[] nStartPos; //开始位置 tPv3nh  
long[] nEndPos; //结束位置 dQX<X}  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 5*M3sN  
long nFileLength; //文件长度 pKeK6K\8  
boolean bFirst = true; //是否第一次取文件  -&N^S?  
boolean bStop = false; //停止标志 $AGW8"  
File tmpFile; //文件下载的临时信息 n}KF)W=  
DataOutputStream output; //输出到文件的输出流 &I8Q'  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） nitKX.t8  
public SiteFileFetch(SiteInfoBean bean) throws IOException EL*O
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{ Z~&$s  
siteInfoBean = bean; m<7Ax>  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); j#}wg`P"A  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); \"L ;Ct 8  
if(tmpFile.exists ()) e70#"~gt[  
{ _ELuQ>zM]+  
bFirst = false; MIV<"A  
read_nPos(); L="ipM:Z  
} !V<c:6"  
else vJybhdvP  
{ I-?PTr  
nStartPos = new long[bean.getNSplitter()]; 0\qLuF[)  
nEndPos = new long[bean.getNSplitter()]; R,]J~TfPK  
} x;Qs_"t];3  
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} y {&"g  
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public void run() .<#oLM^  
{ yf > rG  
//获得文件长度 d-GU164  
//分割文件 ,iUWLcOM  
//实例FileSplitterFetch ;rp("<g:>  
//启动FileSplitterFetch线程 Z2Q'9C},m  
//等待子线程返回 Alo;kt@x  
try{ w'[^RZW:j  
if(bFirst) c@eQSy  
{ j ^Tb=  
nFileLength = getFileSize(); 8IeE7  
if(nFileLength == -1) uPe&i5YR  
{ p(B
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System.err.println("File Length is not known!"); ,, 8hU7P  
} 3shRrCL0mf  
else if(nFileLength == -2) }da}vR"iL  
{ 1/JtL>SKE  
System.err.println("File is not access!"); h>w(Th\H  
} )JNUfauyT  
else bcM65pt_C  
{ Z-md$=+}w  
for(int i=0;i<nStartPos.length;i++) L1Hk[j]X|  
{ xE$>;30b_  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); L=7Y~aL=  
} 8fI]QW  
for(int i=0;i<nEndPos.length-1;i++) nj90`O.K  
{ V(lxkEu/Fj  
nEndPos = nStartPos[i+1]; 3^jkd)xw  
} M%yeI{m  
nEndPos[nEndPos.length-1] = nFileLength; ?*{Vn5aX{  
} )9pRT dT  
} oouhP1py,  
G+_Q7-o&d6  

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//启动子线程 i1c z+}  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Quq X4  
for(int i=0;i<nStartPos.length;i++) Ihn#GzM?u  
{ [Sj _=  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), `@_jDo  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), %qycxEVP  
nStartPos,nEndPos,i); K~chOX  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); a^#\"c  
fileSplitterFetch.start(); MH0xD  
} O:%,.??<%  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), B;vpG?s{9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); MvCB|N"qy  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", xYLTz8g=  
nEndPos = " + nFileLength); zfsGf'U  
// fileSplitterFetch[nPos.length-1].start();  BN_I#8r  
nB|m!fi<  
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//等待子线程结束 {uCXF~v  
//int count = 0; 6"o,)e/z  
//是否结束while循环 De<kkR{4  
boolean breakWhile = false; ,(;TV_@$  
8wf[*6VwV  
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while(!bStop) 6

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{ +A;AX.mr  
write_nPos(); su}n3NsJ  
Utility.sleep(500); @cS(Bb!(M  
breakWhile = true; P&snIJ  
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for(int i=0;i<nStartPos.length;i++) GG=R!+p2  
{ X/8TRi
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if(!fileSplitterFetch.bDownOver) 2Wx~+@1y  
{ =Hd+KvA  
breakWhile = false; K,f"Q<sU%  
break; rOo|.4w  
} up;^,I
  
} _{C =d3  
if(breakWhile) n40&4n  
break; P\rA>ZY  
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.T\jEH8E  
//count++; ,hVDGif  
//if(count>4) g7l?/p[n  
// siteStop(); 6k=
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} #dj,=^1_14  
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System.err.println("文件下载结束！"); EyDH-}Y  
} +a'["Gjq;  
catch(Exception e){e.printStackTrace ();} j /)A<j$  
} oc>N| ww:  
4(D1/8  
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//获得文件长度 lD-HQd  
public long getFileSize() VkD}gJY  
{ Q`zW[Y&]  
int nFileLength = -1; =K;M\_k%y  
try{ (7 O?NS  
URL url = new URL(siteInfoBean.getSSiteURL()); 2[X\*"MQ2  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); G_E \p%L>]  
httpConnection.setRequestProperty("User-Agent","NetFox"); "nA~/t=  
3
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?ZAynZF|#  
int responseCode=httpConnection.getResponseCode(); U3^3nL-M9  
if(responseCode>=400) &Cm$%3  
{ %jh gKq  
processErrorCode(responseCode); [Te"|K':  
return -2; //-2 represent access is error \Gm\sy  
} 2uzy]faM  
>$:_M*5  
 nJ|M  
String sHeader; QB<~+dW  
M\D25=(  
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for(int i=1;;i++) (7A-cC  
{ d",VOhW7)S  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); DEQ7u`6  
//Utility.log(in.readLine()); :KI0j%>2y  
sHeader=httpConnection.getHeaderFieldKey(i); y]}N[l  
if(sHeader!=null) 9)$g
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{ df{6!}/(  
if(sHeader.equals("Content-Length")) ;v5Jps2^]  
{ vlo!D9zsV3  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); \xKhbpO~  
break; QB#_Wn  
} y3ST0=>j}  
} {
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else J~}i}|YC>  
break; ]\F}-I[  
} #c(BBTuX  
} TTJj=KPA  
catch(IOException e){e.printStackTrace ();} 3Qd%`k  
catch(Exception e){e.printStackTrace ();} Yb?(Q%  
bd&Nf2  
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Utility.log(nFileLength); %=)%$n3=-M  
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return nFileLength; QPX3a8w*  
} i2Sh^\Xw  
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//保存下载信息（文件指针位置） >NZJ-:t  
private void write_nPos() il7gk<  
{ LZ8xh  
try{ %[OZ;q& X  
output = new DataOutputStream(new FileOutputStream(tmpFile)); `!C5"i8+i2  
output.writeInt(nStartPos.length); (H-kWT  
for(int i=0;i<nStartPos.length;i++) BOme`0
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{ ?>q5Abp[  
// output.writeLong(nPos); Hm]\.ZEy  
output.writeLong(fileSplitterFetch.nStartPos); z q@"qnr  
output.writeLong(fileSplitterFetch.nEndPos); 9`Xr7gmQf  
} GriFb]ml"  
output.close(); R) J/z  
} Xz"xp8Hc(6  
catch(IOException e){e.printStackTrace ();} ;O {"\H6  
catch(Exception e){e.printStackTrace ();} [s F/sa3  
} Hd{@e6S  
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//读取保存的下载信息（文件指针位置）
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private void read_nPos() ddEV@2F  
{ oG=4&SQ  
try{ T&->xef=  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); yK0iW  
int nCount = input.readInt(); Dyh|F\T  
nStartPos = new long[nCount]; cG5u$B  
nEndPos = new long[nCount]; Mh=j^ [4Q  
for(int i=0;i<nStartPos.length;i++) w\ddC DZ  
{ 0A F}wz>  
nStartPos = input.readLong();  6Ok]E`  
nEndPos = input.readLong(); qP72JxT  
} x<=R?4@rq  
input.close(); g5t`YcL  
} B>%;"OMp  
catch(IOException e){e.printStackTrace ();} sfs2kiH  
catch(Exception e){e.printStackTrace ();} } ^WmCX2a  
} j"n"=rTTQ  
{Z#=ppvs  
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private void processErrorCode(int nErrorCode) c>BDw<  
{ !"dAwG?S  
System.err.println("Error Code : " + nErrorCode); Amv:dh  
} =gHUY&sPu8  
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$t.M`:G  
//停止文件下载 Zo@  
public void siteStop() A }d\ND  
{ /-Nq DRmJ  
bStop = true; <P#:dS%r  
for(int i=0;i<nStartPos.length;i++) 4MP8t@z  
fileSplitterFetch.splitterStop(); TiD|.a8S  
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5?|yYQM0tK  
} [BFPIVD)h]  
} Uwg*kJ3H  
//负责部分文件的抓取 &[kFl\  
**FileSplitterFetch.java %wN*Hu~E
  
*/ QZFH>,d  
package NetFox; 4}Yn!
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import java.io.*; 41I2t(H @z  
import java.net.*; D/puK  
,&s%^I+CC  
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public class FileSplitterFetch extends Thread { :Q"p!,X=-  
!wH'dsriD  
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String sURL; //File URL h/..cVD,K  
long nStartPos; //File Snippet Start Position JwdvY]  
long nEndPos; //File Snippet End Position LQJC]*b1  
int nThreadID; //Thread's ID n= FOB0=  
boolean bDownOver = false; //Downing is over L+_ JKc  
boolean bStop = false; //Stop identical sU"sd7#A  
FileAccessI fileAccessI = null; //File Access interface UL`%Xx  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException YD] :3!MI  
{ f s2}a  
this.sURL = sURL; NV`=T?1[5  
this.nStartPos = nStart; \2M{R  
this.nEndPos = nEnd; N$M:&m3^  
nThreadID = id; /]9(InM9/  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 rtz ]PH  
} rbI 7 3'  
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public void run() wLy:S.r  
{ |J:m{  
while(nStartPos < nEndPos && !bStop) *z)+'D*+  
{  BF /4  
-V=,x3Zew  
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try{ k<y~n*{_  
URL url = new URL(sURL); hQaa"U7[  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); /g$8JL  
httpConnection.setRequestProperty("User-Agent","NetFox"); Qb'Q4@.  
String sProperty = "bytes="+nStartPos+"-"; +.McC$!s  
httpConnection.setRequestProperty("RANGE",sProperty); 0Z jE(3i  
Utility.log(sProperty); na_Wp^;  
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InputStream input = httpConnection.getInputStream(); e)aH7Jj#  
//logResponseHead(httpConnection); YqYobL*q/  
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byte[] b = new byte[1024]; vGchKN~_  
int nRead; lf_q6y  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) p_CCKU  
{ M2LW[z  
nStartPos += fileAccessI.write(b,0,nRead); D;6C2>U~L  
//if(nThreadID == 1) ](>YjE0  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); gQuU_dbXSB  
} (8Te{Kh'  
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Utility.log("Thread " + nThreadID + " is over!"); aMaqlqf  
bDownOver = true; U3t)yr h  
//nPos = fileAccessI.write (b,0,nRead); SbH} cu8  
} fK+[r1^  
catch(Exception e){e.printStackTrace ();} rS_pv=0S  
} CmdPa!4)  
} Xw&vi\*m  
QsyM[;\j:  
m.c2y6<=  
//打印回应的头信息 X)S4vqf}  
public void logResponseHead(HttpURLConnection con) Kc+TcC  
{ :a_MT  
for(int i=1;;i++) nKe|xP  
{ D:PrFa  
String header=con.getHeaderFieldKey(i); M>u84|`  
if(header!=null) 1HUe8m[#3  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); B*n_ VBd  
Utility.log(header+" : "+con.getHeaderField(header)); L\\'n )  
else  ja^  
break; 6<No_x |_  
} 5E}!TL$  
} 6yXN7L==x  
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!}=#h8fv  
public void splitterStop() ;upYam"  
{ )zu m.6pT  
bStop = true; \:E=B1  
} OhTd>~R`<  
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;9hS_%ldX4  
} *ch7z|wo.  
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a  
/* eNr2-R  
**FileAccess.java 0">9n9  
*//文件访问(定位，写) Gg6<4T1  
package NetFox; a6hDw'8!  
import java.io.*; B0,C!??5  
%[BOe4[  
)V9wU1.  
public class FileAccessI implements Serializable{ nS]Ih0(K  
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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 )No>Q :t  
RandomAccessFile oSavedFile; 9HZR%s[J  
long nPos; dI~{0)s
 
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]~\%ANoi  
public FileAccessI() throws IOException ef:YYt{|q  
{ B4w/cIj_  
this("",0); L+.-aB2!d  
} UGQHwz  
7:n OAN}%  
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public FileAccessI(String sName,long nPos) throws IOException D}nIF7r2N  
{ "(vm0@8><  
oSavedFile = new RandomAccessFile(sName,"rw"); VIuzBmR|\  
this.nPos = nPos; j "e]Ui  
oSavedFile.seek(nPos); JF(&+\i<p  
} #=czqZw  
-"d&Ow7o  
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public synchronized int write(byte[] b,int nStart,int nLen) d Z
xrIWx  
{ MR.c?P?0Q  
int n = -1; f# sDG  
try{ Ummoph7_@  
oSavedFile.write(b,nStart,nLen); Ev,b5KelD  
n = nLen; 5KL??ao-  
} 7rIEpN>*  
catch(IOException e) #F ;@Qi3z  
{ j:[#eC  
e.printStackTrace (); AV;x'H7G  
} NH!x6p]n  
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return n; @H8CU!J  
} cR!Mn$m  
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} Sw~L M&A  
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/* y#-~L-J_R  
**SiteInfoBean.java quiX"lV(  
*/ @@#(<[S\B  
package NetFox; U] av{}U  
M6z$*?<  
Imz1"+E~  
public class SiteInfoBean { C ,#D4  
sdXZsQw  
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private String sSiteURL; //Site's URL 1_5]3+r_U-  
private String sFilePath; //Saved File's Path `tJ"wpCf6  
private String sFileName; //Saved File's Name Wrs6t  
private int nSplitter; //Count of Splited Downloading File ;I]$N]8YI  
o*:D/"gb  
b$=c(@]  
public SiteInfoBean() -
02.n
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{//nSplitter的缺省值为5 !">EZX  
//default value of nSplitter is 5 j&Y{ CFuZ  
this("","","",5); )q>q
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} .Tc?PmN  
Q =4~uz|  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 6}?5Oy_XF2  
{ P/T`q:<H   
sSiteURL= sURL; 3/EJ^C  
sFilePath = sPath; SVqKG+{My  
sFileName = sName; eOs4c`  
this.nSplitter = nSpiltter; @T&w nk  
; nYR~~  
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} QR h %S{  
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&6\f;T4  
public String getSSiteURL() ?5rM'O2  
{ TQ25"bWi  
return sSiteURL; 0EBHRY_F  
} eD0|6P;Ei  
8eD/9PD=F  
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public void setSSiteURL(String value) -k,?cEjCs  
{ e+Sq&H!@  
sSiteURL = value; p%-m"u  
} h?-M+Ac  
&?3P5dy_  
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public String getSFilePath() _t@9WA;+\  
{ aHBM9%gV  
return sFilePath; (n4Uc308  
} &f
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>W^)1E,Qh  
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public void setSFilePath(String value) ]vZ}4Xno  
{ M nDaag  
sFilePath = value; "rR$2`v"  
} #
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x)-n[Fu  
public String getSFileName() 8QN/D\uq  
{ dW#?{n-H<  
return sFileName; 6yhRcvJ}  
} `{'h+v`  
*2r(!fJP=^  
tS6r4d%~=  
public void setSFileName(String value) aIklAj)=  
{ XseP[  
sFileName = value; [A#>G4a<  
} 7WEoyd  
t[X,m]SX  
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public int getNSplitter() fP;2qho  
{ ZG1 {"J/z  
return nSplitter; 2GJp`2(%dA  
} AqjEz+TVt  

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public void setNSplitter(int nCount) 2>Sr04Pt  
{ n
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nSplitter = nCount; d?>pcT)G_  
} !sav~dB)  
} ?D=t:=  
rlXMrn  
xqzB=0  
/* MFsW  
**Utility.java }Fb966 $  
*/ E9:p A5H-j  
package NetFox; }!@X(S!do  
tnFhL&  
3Qu Ft~@@  
public class Utility { GE |P)VO  
hSU|rVi  
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public Utility() sH\h{^  
{ <(B: "wI  
f%c
-  
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} *","u;&  
Mx=L lC)  
//线程睡眠 :1e'22[=.  
public static void sleep(int nSecond) 6Y/TqI[   
{ |n\(I$  
try{ psB9~EU&Q  
Thread.sleep(nSecond); =pn(5
6  
} }d16xp  
catch(Exception e) 0A.9<&Lod  
{ o3>D~9  
e.printStackTrace (); CUa`#  
} 6cbIs_g  
} a~O](/+p;  
E]%&)3O[  
//日志 fg~9{1B
 
public static void log(String sMsg) q%c"`u/v/  
{ X1\ao[t<;c  
System.err.println(sMsg); $/;<~Pzi  
} @4%x7%+[c  
I)}T4OOc/  
Wup%.yT~Ds  
public static void log(int sMsg) h/\/dp/tt  
{ >y^zagC*  
System.err.println(sMsg); 2[yfo8H  
} H&=3rkX  
} _dynqF8*  
{ZD'l5jU  
iM{UB=C  
/* ~OOD#/  
**TestMethod.java v#Y
9O6g]T  
*/ r`!S*zK  
package NetFox; cS#m\O  
AX2On}&bf  
9$e6?<`(Y  
public class TestMethod { -'Y
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^%2S,3*0  
public TestMethod() L+d4&x  
{ ///xx/weblogic60b2_win.exe Y<9Lqc.i  
try{ <[<]+r&*  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); pPtw(5bH  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); r
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SiteFileFetch fileFetch = new SiteFileFetch(bean); J-+p]xG  
fileFetch.start(); /d]{ #,k  
} p/.[cH  
catch(Exception e){e.printStackTrace ();} Acx
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ro*$OLc/  
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} 5sK1rDN  
:} 9Lb)Yp  
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public static void main(String[] args) 7T-}oNaJA\  
{ Wf!<Qot|R#  
new TestMethod(); Y)OTvKrOA  
} LwS>jNJx  
} M>"J5yqR  
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