http断点续传简单实现（java)

/* j)'V_@  
**SiteFileFetch.java zRsT6u  
*/ [WY NA-O  
package NetFox; _ nS';48  
import java.io.*; }Jh!B|  
import java.net.*; <*2.B~  
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public class SiteFileFetch extends Thread { zu*0uL  
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SiteInfoBean siteInfoBean = null; //文件信息Bean W\N-~9UA  
long[] nStartPos; //开始位置 b0ri
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long[] nEndPos; //结束位置 Xb)XV$0  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 $M$oNOT}Y  
long nFileLength; //文件长度 T7Lk4cU  
boolean bFirst = true; //是否第一次取文件 K&D -1u  
boolean bStop = false; //停止标志 \P&'4y~PL  
File tmpFile; //文件下载的临时信息 EG7
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DataOutputStream output; //输出到文件的输出流 y 9/27yWB  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） q<,?:g$k  
public SiteFileFetch(SiteInfoBean bean) throws IOException yr[iAi"  
{ IDdhBdQ  
siteInfoBean = bean; EOVHTDkKf  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); .6(Bf$E  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ?n?Ep[D  
if(tmpFile.exists ()) lOI(+74  
{ 8 x|NR?  
bFirst = false; Vnv<]D zC  
read_nPos(); fHlmy[V+M  
} 67/hhO  
else 2EQ:mjxk  
{ 2X]2;W)S;  
nStartPos = new long[bean.getNSplitter()]; g#9KG  
nEndPos = new long[bean.getNSplitter()]; /<zBcpVNV  
} WTY{sq\' o  
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} k{y@&QNj  
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public void run() n
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{ Zhz.8W  
//获得文件长度 7!<cU  
//分割文件 Z-Bw?_e_K  
//实例FileSplitterFetch [AE]0cO@  
//启动FileSplitterFetch线程 L7q%u.nB1  
//等待子线程返回 6
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try{ jW?.>(  
if(bFirst) t#6gjfIi  
{ N''9Bt+:  
nFileLength = getFileSize(); -;Cl0O%  
if(nFileLength == -1) e|"`W`"-  
{ Y]B2-wt-  
System.err.println("File Length is not known!"); l: 1Zq_?v;  
} ,)S|%tDW  
else if(nFileLength == -2) \W??`?Idh  
{ Hd2Sou4-j  
System.err.println("File is not access!"); ~iEH?J%i1r  
} $LFzpg  
else @"'1"$  
{ y?CEV-3+  
for(int i=0;i<nStartPos.length;i++) 19bP0y  
{ ,t*
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); fo4j^,`  
} VAsaJ`vcb  
for(int i=0;i<nEndPos.length-1;i++) Y;xVB" (  
{ $N+a4  
nEndPos = nStartPos[i+1]; Le|Ho^h,Y
 
} vxk1RL*Xu  
nEndPos[nEndPos.length-1] = nFileLength; ^3*/x%A,g  
} |a3)U%rUEQ  
} pWwaN4  
1ncY"S/VO  
%]r@vjeyd  
//启动子线程 6$9n_AS  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; oizD:|  
for(int i=0;i<nStartPos.length;i++) )/Ee#)z*  
{ ?9OiF-:n  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 0Evmq3,9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), {-7];e  
nStartPos,nEndPos,i); &>*fJ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^
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fileSplitterFetch.start(); ~ NKw}6  
} 2\CFt;fk  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Z[ZqQ` 7N  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 8e[kE>tS._  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", `GqS.O}C  
nEndPos = " + nFileLength); 'fy1'^VPAV  
// fileSplitterFetch[nPos.length-1].start(); m9wV#Ldu  
j
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b@/z^k{%  
//等待子线程结束 ?VC
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//int count = 0; ]Tx8ImD#)A  
//是否结束while循环 VbKky1a@  
boolean breakWhile = false; mxGa\{D#y  
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while(!bStop) H}dsd=yO  
{ do+HPnfDzU  
write_nPos(); tceQn ^|<  
Utility.sleep(500); 5m=3{lBi  
breakWhile = true; *&% kkbA  
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for(int i=0;i<nStartPos.length;i++) TStu)6%`  
{ TsfOod   
if(!fileSplitterFetch.bDownOver) P%ev8]2  
{ #J\
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breakWhile = false; n/=&?#m}d  
break; Me`jh8(K\6  
} &t5pJ`$(Cy  
} z"Gk K
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if(breakWhile) Z>wg o@z%  
break; <6Y o
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//count++; PHyS^J`  
//if(count>4) !D7/Ja  
// siteStop(); *
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} L/"u,~[  
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System.err.println("文件下载结束！"); kK16+`\+  
} cr27q6_  
catch(Exception e){e.printStackTrace ();} vMRM/.  
} |F iL1_  
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//获得文件长度 T]Vh]|_s  
public long getFileSize() xD8x1-  
{ n,wLk./`  
int nFileLength = -1; dp&4G6Y<A  
try{ Fm#4;'x5E  
URL url = new URL(siteInfoBean.getSSiteURL()); yCf*ts1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :cnH@:  
httpConnection.setRequestProperty("User-Agent","NetFox"); zEl@jK,{$  
W
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int responseCode=httpConnection.getResponseCode(); Qx>S>f  
if(responseCode>=400) ";J1$a  
{ 7;dV]N  
processErrorCode(responseCode); {[m %1O1  
return -2; //-2 represent access is error 94 H\,}i8  
} JY"<b6C^  
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String sHeader; Y`uL4)hR5  
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for(int i=1;;i++) g|9'Lk  
{ R.Ao%VT  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 8*V3g_z  
//Utility.log(in.readLine()); :5L9tNr{_  
sHeader=httpConnection.getHeaderFieldKey(i); NJ/6_e  
if(sHeader!=null) RQ X  
{ nBgksB*A  
if(sHeader.equals("Content-Length")) ?}D@{%O3T  
{ )Jz L  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); m;>HUTj  
break; N32!*TsWs  
} ?i>.<IPOq  
} )|~pocXt<  
else ~]*P/'-{#  
break; j,K]TJ  
} u%Bk"noCa  
} w`bojM@e1  
catch(IOException e){e.printStackTrace ();} nAZuA]p}S]  
catch(Exception e){e.printStackTrace ();} 21O!CvX  
? DWF7{1  
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Utility.log(nFileLength); k
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return nFileLength; 9KN75<n  
} AMp[f%X  
v/ dSz/<]  
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//保存下载信息（文件指针位置） V*@pmOhz  
private void write_nPos() EJ`JN|,M  
{ YLVIn_\}  
try{ @/@#,+  
output = new DataOutputStream(new FileOutputStream(tmpFile)); E?l_*[G  
output.writeInt(nStartPos.length); xL3-(K6e
 
for(int i=0;i<nStartPos.length;i++) c:.k2u  
{ 3fgVvt-2  
// output.writeLong(nPos); h2#G  
output.writeLong(fileSplitterFetch.nStartPos); \{ r%.G  
output.writeLong(fileSplitterFetch.nEndPos); #eD@sEn  
} `f,SY  
output.close(); Ob$|IH8.  
} ftw\oGrS  
catch(IOException e){e.printStackTrace ();} hF"yxucj$  
catch(Exception e){e.printStackTrace ();} 8_US.52V  
} dE=4tqv-r  

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//读取保存的下载信息（文件指针位置） ijOUv6=-  
private void read_nPos() 494"-F6  
{ 2 1.;lj  
try{ y#!8S{  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); HP}d`C5<R  
int nCount = input.readInt(); Nih8(pbe  
nStartPos = new long[nCount]; 6}
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nEndPos = new long[nCount]; QCIH1\`jW  
for(int i=0;i<nStartPos.length;i++) %e.tAl"!$  
{ "a %5on  
nStartPos = input.readLong(); k\8]fh)J\7  
nEndPos = input.readLong(); ln-+=jk  
} vY&[=2=  
input.close(); 78&jaw*1A  
} {s&6C-  
catch(IOException e){e.printStackTrace ();} ~1jSz-s  
catch(Exception e){e.printStackTrace ();} JE9SPFQx9M  
} 8Ux3,X=  
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private void processErrorCode(int nErrorCode) RoCX*3d  
{ qN%i$mJTo  
System.err.println("Error Code : " + nErrorCode); A0Pg|M  
} tu8n1W  
&i179Qg!  
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//停止文件下载 FvQ>Y')R7Z  
public void siteStop() !

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{ .Az'THD}  
bStop = true; x8YuX*/I  
for(int i=0;i<nStartPos.length;i++) 'o;>6u<u  
fileSplitterFetch.splitterStop(); V+myGsr`  
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} H/n3il_-I  
} &~Qi+b0!  
//负责部分文件的抓取 5]D"y Ay81  
**FileSplitterFetch.java (!`TO{!6P  
*/ p2s*'dab7  
package NetFox; N]f"+  
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import java.io.*; <
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import java.net.*; %2>ya>/M  
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public class FileSplitterFetch extends Thread { uf4C+c
i  
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String sURL; //File URL ?Ho~6q8O@  
long nStartPos; //File Snippet Start Position =g)|g+[H  
long nEndPos; //File Snippet End Position K'z|a{ru.{  
int nThreadID; //Thread's ID #Duz|F+%  
boolean bDownOver = false; //Downing is over hZ6CiEJB  
boolean bStop = false; //Stop identical ig|ol*~  
FileAccessI fileAccessI = null; //File Access interface _ T ;+*  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException P?D;BAP2  
{ }Jfi"L  
this.sURL = sURL; Ch;C\H:X  
this.nStartPos = nStart; 8Ac5K!  
this.nEndPos = nEnd; 9,8}4Y=GVI  
nThreadID = id; 92zo+bc  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 C8 [W  
} Z#w@ /!"}T  
:ZrE/3_S  
8
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public void run() hI249gW9  
{ ^W}(]jL  
while(nStartPos < nEndPos && !bStop) #J&4
5  
{ \H <k  
Y v22,|:  
&)Y26*(`  
try{ HAa$pGb  
URL url = new URL(sURL); ]3UEju8$  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ';<gc5EK  
httpConnection.setRequestProperty("User-Agent","NetFox"); 1Q-O&\-xg  
String sProperty = "bytes="+nStartPos+"-"; =P>c1T1-  
httpConnection.setRequestProperty("RANGE",sProperty); cbsU!8
 
Utility.log(sProperty); |-kU]NJFR  
3!]S8Y*LQP  
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InputStream input = httpConnection.getInputStream(); DdO$&/`)YP  
//logResponseHead(httpConnection); Npu#.)G  
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byte[] b = new byte[1024]; zl~`>  
int nRead; 6R_G{AWLL  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) dk}T&qZ~p  
{ ig:E`Fe@  
nStartPos += fileAccessI.write(b,0,nRead); &,vPZ,7l  
//if(nThreadID == 1) FwD"Pc2  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); doeYc  
} Ci{
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GI:
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Utility.log("Thread " + nThreadID + " is over!"); C9+`sFau@  
bDownOver = true; g~,"C8-H  
//nPos = fileAccessI.write (b,0,nRead); jN.'%5Q?H  
} i n}N[  
catch(Exception e){e.printStackTrace ();} `` !BE"yN  
} aB@D-Y"HO  
} {{'GR"D  
=Yd{PZ*fR  
Hrz#So\#  
//打印回应的头信息 9/[1a_ r  
public void logResponseHead(HttpURLConnection con) A^\A^$|O6  
{ Ns3k(j16  
for(int i=1;;i++) Zp:(U3%  
{ /F/zMZGSA{  
String header=con.getHeaderFieldKey(i); V)HX+D>  
if(header!=null)
P[E:=p  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 4rpx  
Utility.log(header+" : "+con.getHeaderField(header)); kl(id8r  
else btb$C  
break; 8HL$y-F  
} i6)7)^nG  
} 0[ (Z48  
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public void splitterStop() ~96fyk
|  
{ 4.>rd6BAN-  
bStop = true; I.V?O}   
} k5s8s@  
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} j%7N\Vb  
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/* 4$HU=]b6Tf  
**FileAccess.java uPbGQ:%}  
*//文件访问(定位，写) 6h?v/\  
package NetFox; ;?q>F3n  
import java.io.*; .eNeqC  
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public class FileAccessI implements Serializable{ \H^A@f  
X&bz%I>v  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 nq/SGo[c  
RandomAccessFile oSavedFile; =x &"aF1  
long nPos; {E 'go]  
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public FileAccessI() throws IOException cZb5h 9  
{ >.xgo6  
this("",0); VR'R7  
} GR%h3HO2&  
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VZhHO d  
public FileAccessI(String sName,long nPos) throws IOException d~|/LR5  
{ 8:9/RL\"x  
oSavedFile = new RandomAccessFile(sName,"rw"); Qm(KvL5  
this.nPos = nPos; G`D~OI  
oSavedFile.seek(nPos); [ Q@rW5,-  
} _aaQ1A`p  
KUE}^/%z  
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public synchronized int write(byte[] b,int nStart,int nLen) )<
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{ U!TSAg
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int n = -1; crDm2oA~t  
try{ J#/L}h;qH  
oSavedFile.write(b,nStart,nLen); ##\ <mFE  
n = nLen; aAi"  
} U+4W9zhwo  
catch(IOException e) M^6!{c=MIi  
{ C/JFb zVx  
e.printStackTrace (); ^e~m`R2fHh  
} j,Vir"-)  
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return n; W,D$=Bg  
} #}lq2!f6  
!vY5X2?tr,  
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} _!K@(dl  
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/* @p\te7(P%  
**SiteInfoBean.java 5*#3v:l/9  
*/ +
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package NetFox; "J=A(w5   
TIIwq H+h.  
4k]DktY}.  
public class SiteInfoBean { FSNzBN  
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l`b%imX  
private String sSiteURL; //Site's URL d^:(-2l-  
private String sFilePath; //Saved File's Path },& =r= B  
private String sFileName; //Saved File's Name <cUaIb;(4  
private int nSplitter; //Count of Splited Downloading File G?e\w+}Pj@  
qy^sdqHl@  
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public SiteInfoBean() fnJ!~b*qo  
{//nSplitter的缺省值为5 WWtksi,  
//default value of nSplitter is 5 rP<S =eb  
this("","","",5); g+zfa.wQ  
} lD]/Kx  
){M)0,:  
&`}8Jz=S  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) T/YvCbo  
{ IPxK$nI^  
sSiteURL= sURL; \*r]v;NcP  
sFilePath = sPath; "l7))>lL  
sFileName = sName; dp=#|!jc  
this.nSplitter = nSpiltter; +}Q@
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x/]]~@:  
tEC`
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} ]*\m@lWu  
p J#<e  
#$*l#j"#A  
public String getSSiteURL() j%TcW!D-_  
{ QBwgI>zfS"  
return sSiteURL; j{:>"6  
} _N2tf/C&=  
-A3>+G3[  
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public void setSSiteURL(String value) 9+"\7MHw  
{ S1Ql%Yk-(  
sSiteURL = value; Wti?J.Csc  
} Au[H!J  
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Xb/^n.>  
public String getSFilePath() pU)g93  
{ Vv<Tjr  
return sFilePath; h
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} =0gfGwD{  
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Q ,6[  
public void setSFilePath(String value) O9Fg_qfuT_  
{ lWe1Q#  
sFilePath = value; .V'=z|   
} 8Ug`2xS<_  
Ljq!\D  
dLnu\bSF  
public String getSFileName() ,f2tG+P  
{ cJQ&#u  
return sFileName; :Tu%0="ye  
} :4'Fq;%C  
D/7hVwMw:
 
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public void setSFileName(String value) Ei& Z  
{ &8^ch,+pD  
sFileName = value; KfkE'_F  
} m=.}}DcSs  
r|!r!V8j  
$GcVI;a  
public int getNSplitter() R]8^ @i1  
{ xM6v0Ua  
return nSplitter; {6uhUb  
} O"Ua|8  
#vnJJ#uI|>  
|Vq&IfP  
public void setNSplitter(int nCount) 3$hbb6N%6.  
{ k=o>DaEh(  
nSplitter = nCount; SFdSA4D"  
} rDvz2
p"R  
} ; Da[jFP  
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{#Vck\&  
/* 2*<'=*zaQ  
**Utility.java 5/{";k)L+  
*/ 3jG #<4;J  
package NetFox; xU5+"t~  
*[MK{m  
!o k6*m  
public class Utility { Gd08RW  
m=7Z8@sX},  
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gtk  
public Utility() !R/-|Kjy  
{ lxvRF93a.  
$4j$c|S!  
Q'mLwD3>  
} y_Tc$g~  
S5$sB{\R  
//线程睡眠 D#?jddr-  
public static void sleep(int nSecond) :1O1I2L0  
{ QV@NA@;XZ  
try{ AvNU\$B4aG  
Thread.sleep(nSecond); ]XAJ|[]sj*  
} ggR--`D[  
catch(Exception e) 0/F/U=Z!  
{ +u
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e.printStackTrace (); O^AF+c\n  
} cIIt ;q[  
} [3#A)#kWm  
mm5y'=#  
//日志 3nJd0E  
public static void log(String sMsg) U=G^wL  
{ H"g$qSx  
System.err.println(sMsg); <e:2DB&  
} %%w/;o!c  
jW G=k#WN  
/W,K% s]  
public static void log(int sMsg) i(k]}Di:  
{ 
W?B(Jsv  
System.err.println(sMsg); BIr24N  
} K[XFJ9  
} )E2^G)J$W  
i{$h]D_fD  
,z1fiq  
/* DG&[.dR+  
**TestMethod.java X@[)jWs  
*/ { fmY_T[Q8  
package NetFox; 08!pLE  
)38M~/ ^l  
us^2Oplq<  
public class TestMethod { aB(6yBBoxj  
[AZN a  
_IK@K6V1  
public TestMethod() j9=QOq  
{ ///xx/weblogic60b2_win.exe %qM3IVPK)q  
try{ sZ,mRT  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); s]X]jfA.  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 0uf'6<fR  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ( _{\tgSm  
fileFetch.start(); r95l.v  
} "^~>aVuXf  
catch(Exception e){e.printStackTrace ();} 7D;g\{>M  
j3
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} 'kD~tpZ  
#jja#PF]7  
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public static void main(String[] args) B`/cKfg  
{ a09]5>*  
new TestMethod(); )cMW,  
} F_Q?0 Do0'  
} $=?CW(  
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