http断点续传简单实现（java)

/* v1/Y0  
**SiteFileFetch.java J+wnrGoK  
*/ i-.AD4  
package NetFox; >h.HW  
import java.io.*; ~du U& \  
import java.net.*; )~`UDaj_  
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public class SiteFileFetch extends Thread { &qM8)2Y  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 7Hj7b:3K&!  
long[] nStartPos; //开始位置 q s:T
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long[] nEndPos; //结束位置 'T7Y5X80$j  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 nWhf  
long nFileLength; //文件长度 d. ZfK  
boolean bFirst = true; //是否第一次取文件 ca5;Z@t$S  
boolean bStop = false; //停止标志 }}bMq.Q'  
File tmpFile; //文件下载的临时信息 qyh]v[  
DataOutputStream output; //输出到文件的输出流 i 1Kq(7  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） :B\$7+$v  
public SiteFileFetch(SiteInfoBean bean) throws IOException N^AlhR^  
{ TX7dwmt)N  
siteInfoBean = bean; _xBhMu2f  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); K /%5\h  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); B>sQcZ:  
if(tmpFile.exists ()) 4N= gl(  
{ SLp nVD:'1  
bFirst = false; DyA1zwp}  
read_nPos(); Nq|y\3]  
} t;u)_C,bmP  
else m"6K_4r]  
{ /c6]DQ<?  
nStartPos = new long[bean.getNSplitter()]; IkxoW:L  
nEndPos = new long[bean.getNSplitter()]; -BWWaL  
} P+C5 
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} vsQvJDna~  
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public void run() B\l0kiNT  
{ /!y;h-  
//获得文件长度 ] mK{E~Zll  
//分割文件  kKY,&Fn-  
//实例FileSplitterFetch l.Z+.<@  
//启动FileSplitterFetch线程 <I0om(P  
//等待子线程返回 <q Q@OUI   
try{ Qz_4Ms<o  
if(bFirst) XQmg^x[,A  
{ 06v'!M  
nFileLength = getFileSize(); 2=%]Ax"R  
if(nFileLength == -1) c?aOX/C'  
{ Vup|*d2r0E  
System.err.println("File Length is not known!"); G>jC+0nkry  
} :bL^S1et  
else if(nFileLength == -2) r=p^~tuyxr  
{ |KO[[4b ?+  
System.err.println("File is not access!"); <7zz"R  
} Y{Lxo])e  
else hzpl;Mj  
{ NL2D,  
for(int i=0;i<nStartPos.length;i++) '-$cvH7_  
{ Rm6i[y&  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); CkNh3'<wg  
} DJqJ6z:'  
for(int i=0;i<nEndPos.length-1;i++) I :b
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{ {~G~=sC$  
nEndPos = nStartPos[i+1]; rV?@K
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} Vs Z7n~e  
nEndPos[nEndPos.length-1] = nFileLength; (m=1yj9  
} +At0V(  
} ][YuJUK8  
"|R75m,Id  
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//启动子线程 zZey
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; &l4kwds R  
for(int i=0;i<nStartPos.length;i++) NgF"1E  
{ $1Wb`$  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), BxZ7Bk  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), s?4nR:ZC}  
nStartPos,nEndPos,i); SwaPRAF  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'q RQO(9&m  
fileSplitterFetch.start(); `tXd?E/e  
} ( )f)  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Lr=
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); oMOh4NH,x  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 6Tc!=lk  
nEndPos = " + nFileLength); 3Wx\Liw,  
// fileSplitterFetch[nPos.length-1].start(); T21?~jS  

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//等待子线程结束 v!$?;"d+  
//int count = 0; o02G:!gB  
//是否结束while循环 ={;+0Wj
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boolean breakWhile = false; DF g
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while(!bStop) <
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{ ;18u02z^  
write_nPos(); (v? rZv  
Utility.sleep(500); /<%L&
 
breakWhile = true; _>?.MUPB  
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for(int i=0;i<nStartPos.length;i++) <U\
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{ {Ve`VV5E  
if(!fileSplitterFetch.bDownOver) _={mKKoHs  
{ Gi2Fjq/Y  
breakWhile = false; HS\'{4P  
break; y=[{:
 
} 4mp
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} r}:U'zlC{  
if(breakWhile) !(Q@1c&z  
break; 02T'B&&~  
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//count++; &!M6{O=~  
//if(count>4) P_75-0G  
// siteStop(); 9|OOT[  
} }1lZW"{e[  
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System.err.println("文件下载结束！"); t}OzF cyqN  
} L 7LUy$M-<  
catch(Exception e){e.printStackTrace ();} Cn5;h(r  
} -C!m#"P
DW  
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//获得文件长度 40dwp*/!  
public long getFileSize() K*4ib/'E a  
{ U%;E:|  
int nFileLength = -1; }9;mtMR$  
try{ 0W+RVp=TL1  
URL url = new URL(siteInfoBean.getSSiteURL()); 'SrDc'?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); S?OCy4dk:  
httpConnection.setRequestProperty("User-Agent","NetFox"); dNov= w  
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int responseCode=httpConnection.getResponseCode(); LZE9]Gd  
if(responseCode>=400) Ol|
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{ 3 +`,'Q9  
processErrorCode(responseCode); vmo!  
return -2; //-2 represent access is error ej=}OH4  
} G{Uqp
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String sHeader; CUBL/U\=  
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for(int i=1;;i++) 6KPjZC<  
{ N$.ls48a4-  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 4E1j0ARQQ  
//Utility.log(in.readLine()); ejbtdU8N<  
sHeader=httpConnection.getHeaderFieldKey(i); 'AmA3x)9u  
if(sHeader!=null) lEb H4 g  
{ Fx)><+-  
if(sHeader.equals("Content-Length")) uigzf^6,  
{ yD8Qy+6L  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); w6^TwjjZ$  
break; t^%)d7$  
} *e<'|Kq  
} jW[
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else s!Iinc^p  
break; LJt5?zQKrW  
}   &._Mh  
} zn|O)"C  
catch(IOException e){e.printStackTrace ();} rm|,+{  
catch(Exception e){e.printStackTrace ();}
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Utility.log(nFileLength); F:.8O ,%u  
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return nFileLength; 2&AX_#P  
} \rS-}DG  

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//保存下载信息（文件指针位置） <N=ow"rD  
private void write_nPos() ``kesz  
{ KQ(S\  
try{ Kf$6D 79#  
output = new DataOutputStream(new FileOutputStream(tmpFile)); [:A">eYI  
output.writeInt(nStartPos.length); OXX D}-t  
for(int i=0;i<nStartPos.length;i++) 9R&.$5[W(s  
{ +hH7|:JQ  
// output.writeLong(nPos); ;B:\e8  
output.writeLong(fileSplitterFetch.nStartPos); "#Q"gC.K  
output.writeLong(fileSplitterFetch.nEndPos); f uH3C~u7<  
} Dd$8{~h"G  
output.close(); CKU)wJ5t  
} bF
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catch(IOException e){e.printStackTrace ();} ;b_<5S  
catch(Exception e){e.printStackTrace ();} u(`7F(R  
}  BfW@f  
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//读取保存的下载信息（文件指针位置） KXu1%`x=%Z  
private void read_nPos() grJ(z)c  
{ LM!@LQAMY  
try{ dmMr
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); C"h7'+Kw  
int nCount = input.readInt(); 5ai$W`6  
nStartPos = new long[nCount]; U8zs=tA  
nEndPos = new long[nCount]; Vz y )jf  
for(int i=0;i<nStartPos.length;i++) p
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{ t & 5s.  
nStartPos = input.readLong(); !Jaj2mS.N  
nEndPos = input.readLong(); 9;A9Q9Yr  
} 6N.MCB^  
input.close(); 2(Nf$?U@0  
} m!Aw,*m+*  
catch(IOException e){e.printStackTrace ();} Q+E)_5_sA  
catch(Exception e){e.printStackTrace ();} hOm0ND?;1  
} p4Xhs@.k  
(i]0IYMXy*  
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private void processErrorCode(int nErrorCode) 1_)Y{3L  
{ vVbS 4_  
System.err.println("Error Code : " + nErrorCode); .gw6W0\F  
} MAgoxq~;V  
F'njtrO3  
^ }|$_  
//停止文件下载 ZV~9{E8  
public void siteStop() K`kWfPwp  
{ ezr'"1Ba}  
bStop = true; 0C0ld!>r  
for(int i=0;i<nStartPos.length;i++) l'"Ici#7Ls  
fileSplitterFetch.splitterStop(); PE2O$:b\  
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o 0H.DeP  
} uBo~PiJ2"  
} 1K{hj%  
//负责部分文件的抓取 e|.a%,Dcy  
**FileSplitterFetch.java ~P+;_  
*/ WI\h@qSB  
package NetFox; gnZc`)z  
]{pH,vk-  
OBZ:C!  
import java.io.*; u!I=|1s  
import java.net.*; 5`1p ?  
|=sjGf  
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public class FileSplitterFetch extends Thread { WD?COUEox  
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E3h-?ugO'  
String sURL; //File URL 4>te>[  
long nStartPos; //File Snippet Start Position C 4hvk'=  
long nEndPos; //File Snippet End Position o\:vxj+%*  
int nThreadID; //Thread's ID 
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boolean bDownOver = false; //Downing is over 2p8}6y:}7  
boolean bStop = false; //Stop identical ]YwvwmZ  
FileAccessI fileAccessI = null; //File Access interface ?F@X>zR2  
y_f^ dIK*=  
@d6N[?3;  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException >&uR=Yd  
{ 4F?O5&329i  
this.sURL = sURL; jMQ7^(9-  
this.nStartPos = nStart; x.aqy'/`  
this.nEndPos = nEnd; g9:V00^<  
nThreadID = id;
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 rd4mAX6@  
} =fy'w3m  
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4W36VtQ@E  
public void run() BMovl4*5  
{ ?4MZT5 .  
while(nStartPos < nEndPos && !bStop) 8Hh=Sp^  
{ zc%HBZ3p  
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try{ #kPsg9Y  
URL url = new URL(sURL); [,|;rt\o>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); rZ^VKO`~I1  
httpConnection.setRequestProperty("User-Agent","NetFox"); 5WU?Km  
String sProperty = "bytes="+nStartPos+"-"; 95hdQ<W  
httpConnection.setRequestProperty("RANGE",sProperty); ,S\AUUt%  
Utility.log(sProperty); C9"yu&l  
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InputStream input = httpConnection.getInputStream(); F
@Cxjz  
//logResponseHead(httpConnection); [Cf{2WB:7  
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b<"LUM*;  
byte[] b = new byte[1024]; +U*:WKdI?  
int nRead; OysO55
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) |aMeh;X t  
{ %8~g#Z  
nStartPos += fileAccessI.write(b,0,nRead); L(w?.)E  
//if(nThreadID == 1) mUjM5ceAXO  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); S7WT`2  
} u[?M{E/HU  
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 Jyo(Etp  
Utility.log("Thread " + nThreadID + " is over!"); 1QJB4|5R#  
bDownOver = true; { K*  
//nPos = fileAccessI.write (b,0,nRead); +EE(d/f  
} ?_+8K`B  
catch(Exception e){e.printStackTrace ();} ;iTZzmB  
} U.p"JSH L  
} Z}s56{!.  
dPCn6  
~e#QAaXD#5  
//打印回应的头信息 `g!NFp9q  
public void logResponseHead(HttpURLConnection con) z]bcg$m  
{ VAet!
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for(int i=1;;i++) +je{%,*  
{ 1_0\_|  
String header=con.getHeaderFieldKey(i); pIP^/
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if(header!=null) wwVg'V;  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ^U[yk'!Y  
Utility.log(header+" : "+con.getHeaderField(header)); 6h3TU,$r  
else >{@:p`*  
break; n06Jg+  
} N,~"8YSo  
} fNaboNj[  
+!Lz]@9K  
n+%tu"e  
public void splitterStop() A&/VO$Y9wp  
{ yOr5kWqX  
bStop = true; 'e5,%"5(c  
} <9yB& ^  
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)*T<s  
} vQhi2J'  
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FErKr)  
/* fw+ VR.#2H  
**FileAccess.java Zg~6  
*//文件访问(定位，写) JTI 'W  
package NetFox; ruTj#tWSo  
import java.io.*; y&{ Z"+B5  
a-Ef$(i_  
\r7gubD  
public class FileAccessI implements Serializable{ Cv;\cI"&  
|{JJ2c\W  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 \B1<fF2  
RandomAccessFile oSavedFile; ;gmfWHB<  
long nPos; Y~+`F5xX<  
&nX,)"  
*, RxOz2=  
public FileAccessI() throws IOException gg}^@h&?  
{ yNkE>  
this("",0); O| zLD  
} >HlQ+bl$xw  
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<;.
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public FileAccessI(String sName,long nPos) throws IOException @!zT+W&
 
{ \QKr2|  
oSavedFile = new RandomAccessFile(sName,"rw"); h<ULp&g  
this.nPos = nPos; sg!*%*XQ  
oSavedFile.seek(nPos); jYi{[**  
} KQ\d$fX  
1[Ffl^\ARp  
#ZS8}X*S  
public synchronized int write(byte[] b,int nStart,int nLen) {pof=G  
{ O)i]K`jk  
int n = -1; Y%iimbBY|  
try{ ,H+LE$=  
oSavedFile.write(b,nStart,nLen); 8NS1*\z  
n = nLen; RIQw+RG>  
} EFKOElG(k  
catch(IOException e) {f }4l  
{ L_4ZxsIv  
e.printStackTrace (); CWk65tcF  
} ~0~f  
6bW:&IPQ;  
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return n; :*wjC.Z  
} Oor&1  
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} m+m,0Ey5H  
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/* p#Vh[UTl^  
**SiteInfoBean.java pwvcH3l/r  
*/ """gV)Y  
package NetFox; uKcwVEu  
-^sbf.  
d* 6 lJT  
public class SiteInfoBean { iJrF$Xw  
8C{mV^cn~  
R]7-6  
private String sSiteURL; //Site's URL j5EZJ`  
private String sFilePath; //Saved File's Path &l=%*`On  
private String sFileName; //Saved File's Name 1.Ximom  
private int nSplitter; //Count of Splited Downloading File lo*)%fy  
O,kzU,zOs  
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public SiteInfoBean() YYz,sR'%|}  
{//nSplitter的缺省值为5 G Uf[Dz  
//default value of nSplitter is 5 |@x^5Ab$T  
this("","","",5); na&?Cw  
} {/C \GxH+  
4X@ <PX5  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter)  GIt~"X  
{ c7[<X<yk  
sSiteURL= sURL; )5}=^aqd  
sFilePath = sPath; mZ^z%+Ca|  
sFileName = sName; H+`s#'(i_P  
this.nSplitter = nSpiltter; Z.b}  
Lbka*@  
Dk!;s8}*c  
} }dl[~iKW  
9 wun$!>&  
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public String getSSiteURL() .a%D:4GYR  
{ )Jx+R;Z  
return sSiteURL; 2F0@M|'  
} S <C'#vj  
.Vm!Ng )j  
4!pMZ<$3  
public void setSSiteURL(String value) wo($7'.@  
{ g]IRv(gDh  
sSiteURL = value; 42a.@JbLQ  
} )~
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>+iJ(jqq  
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public String getSFilePath() b'9\j.By  
{ =.=4P~T&  
return sFilePath; *f%uc  
} 'c[[H3s!;  
{sn RS)
-  
u^DfRd&P0  
public void setSFilePath(String value) {9kH<,PJ;!  
{ ke'aSD  
sFilePath = value; d"K~+<V}  
} qPEtMvL #  
~=$0=)c  
ftS^|%p  
public String getSFileName() < Y5pAStg  
{ (twwDI  
return sFileName; v6Vieo=  
} ~HWH2g  
!S0$W?*  
[$PW {d8|  
public void setSFileName(String value) KIY/nu   
{ Rra3)i`
*  
sFileName = value; ]mDsd*1  
} [BPK0  
`w&Y[8+E  
{y5v"GR{YM  
public int getNSplitter() d']CBoK  
{ &J>XKO nl  
return nSplitter; 0;Lt  
} F8u;C:^d  
 rG#o*oA  
iLQFce7d|&  
public void setNSplitter(int nCount) h(M_ K  
{ <c`+ fPW  
nSplitter = nCount; Ll" Kxg  
} Y[_{tS#u  
} T;7=05k<_  
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9%{V?r]k  
/* +JyD W%a:L  
**Utility.java (8JL/S;Z$  
*/ K1
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package NetFox; ;kW+  
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public class Utility { @u@N&{b5"  
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,, 8hU7P  
public Utility() ; 9n}P@  
{ V-1H(wRu  
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,.<[iHC}9  
} /nPNHO>U  
ILN Yh3  
//线程睡眠 [8kufMY|  
public static void sleep(int nSecond) 0mt lM(  
{ 5L?_AUL  
try{ jD
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Thread.sleep(nSecond); g-C)y 06  
} [Sj _=  
catch(Exception e) buj*L&  
{ \GF9;N}V  
e.printStackTrace (); l:@`.'-=  
} =<BPoGs5  
} e(z'uA{!  
=qJlSb  
//日志 M~?2g.o'D  
public static void log(String sMsg) r_"=DLx6  
{ ZwFVtR  
System.err.println(sMsg); s)A=hB-V  
} >D\jyd$wh&  
6_=t~9sY  
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public static void log(int sMsg) hifC.guK  
{ +|w%}/N  
System.err.println(sMsg); &6@#W]_  
} K,f"Q<sU%  
} %ij,xN  
Pb]EpyAW  
} %bP9  
/* ;irAq
|  
**TestMethod.java /5wIbmz@I
 
*/ rw }wQP_'  
package NetFox; N51e.;  
p Lwtm@  
,]LsX"u  
public class TestMethod { E4cPCQyeH  
/cX%XZg  

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public TestMethod() yEPkF0?  
{ ///xx/weblogic60b2_win.exe WNK)IC~c  
try{ <hBd #J  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); "nA~/t=  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); /=@V5)  
SiteFileFetch fileFetch = new SiteFileFetch(bean); \sEH)$R'  
fileFetch.start(); (`js/7[`H[  
} 9>-]*7  
catch(Exception e){e.printStackTrace ();} #JYH5:*  
d "%6S*dL  
Yl`)%6'5|  
} w{"ro~9o  
M`49ydh&  
=`OnFdI  
public static void main(String[] args) L#`Vr$  
{ D16w!Mnz{K  
new TestMethod(); Zq"  
} -+z8bZ  
} pnp)- a*7  
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