http断点续传简单实现（java)

/* 2`>/y  
**SiteFileFetch.java vw=OGjT_>m  
*/ {wMw$Fvf  
package NetFox; y;A<R[|Ve  
import java.io.*; WmU4~.  
import java.net.*; pFi.
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public class SiteFileFetch extends Thread { w"d~R   
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SiteInfoBean siteInfoBean = null; //文件信息Bean , f9V`Pz)  
long[] nStartPos; //开始位置 *O-1zIlp  
long[] nEndPos; //结束位置 2%4dA$H#4w  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 _[;>V*?zp5  
long nFileLength; //文件长度 <>$`vuU  
boolean bFirst = true; //是否第一次取文件 ^2E\{$J
 
boolean bStop = false; //停止标志 fkE4[X7f  
File tmpFile; //文件下载的临时信息 p\I,P2on  
DataOutputStream output; //输出到文件的输出流 %7=B?c|  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） *(6vO{  
public SiteFileFetch(SiteInfoBean bean) throws IOException dr0<K[S_  
{ -=BQVJ_dK{  
siteInfoBean = bean; K +n  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); i? 5jl&30  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); @igGfYy  
if(tmpFile.exists ()) *y[i~{7:  
{ q[p+OpA  
bFirst = false; *izPLM}+  
read_nPos(); ({ 'I;]AQ  
} j`jF{k b  
else 1}+lL)-!  
{ HqNM31)  
nStartPos = new long[bean.getNSplitter()]; g a|RW0  
nEndPos = new long[bean.getNSplitter()]; 3YT>3f!\  
} 'o=`1I  
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} gwE#,OY*  
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public void run() r0kJx$f  
{ :*
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//获得文件长度 2u 8z>/G  
//分割文件 iu!j#VO  
//实例FileSplitterFetch x+Vp&  
//启动FileSplitterFetch线程 @IL_  
//等待子线程返回 <)n8lIK  
try{ #\9sCnb  
if(bFirst) #T<<{ RA  
{ EIZSV>  
nFileLength = getFileSize(); sLiKcR8^  
if(nFileLength == -1) ',GWH:B  
{ :SFcnYv0  
System.err.println("File Length is not known!"); UjLZ!-}  
} uk%C:4T  
else if(nFileLength == -2) *Y!'3|T  
{ ;M{@|z[Nv  
System.err.println("File is not access!"); oc.H}Eb%Z  
}  d(PS  
else !Ra.DSL  
{ BR\3ij  
for(int i=0;i<nStartPos.length;i++) qr>:meJy4  
{ A0{ !m  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Cv7FVl-I  
} 3LXS}~&  
for(int i=0;i<nEndPos.length-1;i++) *s4h tt  
{ zK.%tx}+=k  
nEndPos = nStartPos[i+1]; R T/T+Q!  
} H^y%Bi&^  
nEndPos[nEndPos.length-1] = nFileLength; ;/gH6Z?  
} FPj j1U`C  
} r[; .1,(  
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//启动子线程 9_yO6)`  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; pw
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for(int i=0;i<nStartPos.length;i++) -={Z::}S"  
{ tMM*m  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), L"|4 v  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), xEv]VL:  
nStartPos,nEndPos,i); ?kBi9^
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); U$CAA5HV]  
fileSplitterFetch.start(); 7/*Q?ic  
} v:otR%yt  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 72rnMHq  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); xj6ht/qq  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 'iy &%?  
nEndPos = " + nFileLength); c_$9z>$  
// fileSplitterFetch[nPos.length-1].start(); gG"W~O)yv  
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D)C^'/8q  
//等待子线程结束 &8VB{S>r  
//int count = 0; b[+G+V  
//是否结束while循环 Z"spua5  
boolean breakWhile = false; +#qW 0g  
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while(!bStop) sg@)IEg</v  
{ bb<qnB  
write_nPos(); _86pbr9  
Utility.sleep(500); ,S"a ,}8  
breakWhile = true; 5Fh?YS=  
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for(int i=0;i<nStartPos.length;i++) Nb.AsIR^  
{ 5?-cP?|.9  
if(!fileSplitterFetch.bDownOver) }
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{ W)WL1@!Z  
breakWhile = false; 6=ukR=]v  
break; qs\O(K
8  
} A2Je*Gz  
} 29:1crzx~  
if(breakWhile) _`6fGu& W  
break; [S{KGe:g  
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//count++;  Fa  
//if(count>4) $nR1AOm}.B  
// siteStop(); c
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} jKFypIZ4  
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System.err.println("文件下载结束！"); k-;%/:Om  
} qJq49}2  
catch(Exception e){e.printStackTrace ();} 63
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} 5nq0#0Oc  
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//获得文件长度 s>}ScJZK  
public long getFileSize() oU }eAZj{  
{ Pba 6Ay6B  
int nFileLength = -1; 4F_*,
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try{ CiE  
URL url = new URL(siteInfoBean.getSSiteURL()); g\sW2qXEw  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |&JCf=  
httpConnection.setRequestProperty("User-Agent","NetFox"); 6=V&3|"  
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int responseCode=httpConnection.getResponseCode(); VCOz?Y*  
if(responseCode>=400) y*ae 5=6(  
{ S+c)  
processErrorCode(responseCode); ~udi=J|  
return -2; //-2 represent access is error b"U{@  
} 25xpq^Zw  
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String sHeader; r>fx55dw  
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for(int i=1;;i++) bZ!*s  
{ :f^=~#!  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 9f ,$JjX[  
//Utility.log(in.readLine()); ;XFo:?  
sHeader=httpConnection.getHeaderFieldKey(i); 4k9O6  
if(sHeader!=null) f.?p"~!  
{ o(~QuHOp8>  
if(sHeader.equals("Content-Length")) wwnl_9a  
{ *ea%KE":  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); I@dS/  
break; I!IWmU6FN  
} 3QL I|VpO  
} gXtyl]K:  
else Q+e|;Mj  
break; fIOI  
} -phwzR\(t  
} J!?hajw7N  
catch(IOException e){e.printStackTrace ();} =rBNEd  
catch(Exception e){e.printStackTrace ();} ByR%2_6&  

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Utility.log(nFileLength); 8v&4eU'S  
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return nFileLength; _c*0Rr  
} r)$(>/[$  
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//保存下载信息（文件指针位置） ^l\U6$3  
private void write_nPos() &WW|! 6  
{ I;dc[m  
try{ cx?XJ)  
output = new DataOutputStream(new FileOutputStream(tmpFile)); /A3tY"Vn  
output.writeInt(nStartPos.length); 3Qt-%=b&  
for(int i=0;i<nStartPos.length;i++) v=4,kG  
{ aa!o::;  
// output.writeLong(nPos); 0pP;[7k\  
output.writeLong(fileSplitterFetch.nStartPos); _8$arjx=  
output.writeLong(fileSplitterFetch.nEndPos); }e
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} ~9.0:Fm<  
output.close(); 2BA'Zu`  
} 
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catch(IOException e){e.printStackTrace ();} f
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catch(Exception e){e.printStackTrace ();} NFT&\6
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}  M1><K:  
9!hiCqA&  
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//读取保存的下载信息（文件指针位置） #K1VPezN  
private void read_nPos() Obd@#uab  
{ s{v!jZ  
try{ <ptZY.8N  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 7TCY$RcF,I  
int nCount = input.readInt(); T_}
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nStartPos = new long[nCount]; >5Vv6_CI0?  
nEndPos = new long[nCount]; H+&c=~D\_  
for(int i=0;i<nStartPos.length;i++) 7hPiPv  
{ > %5<fK2  
nStartPos = input.readLong(); +o]DT7W  
nEndPos = input.readLong(); -3 .Sr|t  
} b(8#*S!U  
input.close(); Yj+p^@{S2P  
} eR,ePyA;  
catch(IOException e){e.printStackTrace ();} 5[Sa7Mk  
catch(Exception e){e.printStackTrace ();} }?zy*yL  
} Ba$&4?8  
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{ETuaFDM  
private void processErrorCode(int nErrorCode) *n$=2v^A  
{ 2"`R_q  
System.err.println("Error Code : " + nErrorCode); \XaKq8uE  
} qKX3Npw  
&)?ECj0`  
-ea":}/  
//停止文件下载 EHByo[  
public void siteStop() (=n{LMa  
{ 2l5>>yY  
bStop = true; 0fhz7\a^_<  
for(int i=0;i<nStartPos.length;i++) x9UF  
fileSplitterFetch.splitterStop(); +Tnn'^4  
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} s+{)K  
} APydZ  
//负责部分文件的抓取 +C4UM9  
**FileSplitterFetch.java 2H7b2%  
*/ #l kv&.)x  
package NetFox; IbFS8 *a\  
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import java.io.*; -%8*>%  
import java.net.*; L4bx [  
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public class FileSplitterFetch extends Thread { +AGI)uQQ  
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String sURL; //File URL |KF_h^  
long nStartPos; //File Snippet Start Position )erI3?k  
long nEndPos; //File Snippet End Position QMUmPx&  
int nThreadID; //Thread's ID (* WO<V  
boolean bDownOver = false; //Downing is over ~ ;CnwG
  
boolean bStop = false; //Stop identical B(+J?0Dj  
FileAccessI fileAccessI = null; //File Access interface N"A863>  
#~(J J  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 6M({T2e  
{ zo!e<>o  
this.sURL = sURL; A.0eeX{  
this.nStartPos = nStart; |Tn+Aq7  
this.nEndPos = nEnd; VKI`@rY4  
nThreadID = id; {G _ :#cep  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 m0*bz5  
} XxXMtiZ6  
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?];?
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public void run() (^x ,  
{ /l o;:)AiP  
while(nStartPos < nEndPos && !bStop) KxZup\\:v  
{ hzG+s#  
>NL4&MV:  
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try{ $\:;N]Cs~0  
URL url = new URL(sURL); BhJag L ^o  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); tWD5Yh>.?$  
httpConnection.setRequestProperty("User-Agent","NetFox"); 6|h~pH  
String sProperty = "bytes="+nStartPos+"-"; 46p%y  
httpConnection.setRequestProperty("RANGE",sProperty); 2`2S94'  
Utility.log(sProperty); ;3~+M:{2  
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InputStream input = httpConnection.getInputStream(); ,OGXH2!h  
//logResponseHead(httpConnection); uvbXsO"z]]  
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byte[] b = new byte[1024]; puE!7:X7  
int nRead; {,kA'Px)  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ZboY]1L[j  
{ VZ69s{/.B  
nStartPos += fileAccessI.write(b,0,nRead);  D`Tx,^E  
//if(nThreadID == 1) ~yrEB:w`_  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); yL ?dC"c  
} xA?(n!{P  
/j}"4_.8  
>m66j2(H*Z  
Utility.log("Thread " + nThreadID + " is over!"); _ML`Vh]  
bDownOver = true; @Kl'0>U  
//nPos = fileAccessI.write (b,0,nRead); jv<C#0E^  
} "9>.,nzt  
catch(Exception e){e.printStackTrace ();} )21yD1"6  
} m]XG7:}V0  
} 5 5$J%;&  
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m :M=De  
//打印回应的头信息 -Ov
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public void logResponseHead(HttpURLConnection con) w-2?|XvDmf  
{ .(2Zoa  
for(int i=1;;i++) VMa\?`fT  
{ iLvzoQ  
String header=con.getHeaderFieldKey(i); (fSpY\JPI  
if(header!=null) -UTTJnu^  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 86_`Z$ s  
Utility.log(header+" : "+con.getHeaderField(header)); C71\9K*X  
else yu^n;gWH  
break; "2J$~2{N  
} Hi V
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} qj$6/V|D  
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*=b#>//  
public void splitterStop() Py}] {?  
{
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bStop = true; e\Igc.  
} .|Ee,Un  
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Z+3j>_Ss  
} v
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/* OVy ZyZ#  
**FileAccess.java {y>o6OTITR  
*//文件访问(定位，写) E:!qncL:  
package NetFox; [*{G,=tF`Y  
import java.io.*; dc]D 8KX  
,p3moD 3  
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public class FileAccessI implements Serializable{ R=/^5DZ}  
=&9x}4`;%  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 !%8|
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RandomAccessFile oSavedFile; =~|:93]k  
long nPos; 8M5a&35J"  
,.Sd)JB'  
:\Pk>a  
public FileAccessI() throws IOException 8D)I~0\  
{ 62YT)/i3  
this("",0); =W*Js%4  
} }\-"L/D?+  
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public FileAccessI(String sName,long nPos) throws IOException JsDugn ,B  
{ e [}m@
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oSavedFile = new RandomAccessFile(sName,"rw"); BZdryk:S  
this.nPos = nPos; |^&j'k+A  
oSavedFile.seek(nPos); "3\C;B6I  
} $VgazUH% =  
4I
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ytsPk2@WR  
public synchronized int write(byte[] b,int nStart,int nLen) SniKCqmC]  
{ !+F6Bf  
int n = -1; Bkq3-rX\  
try{ ea\b7a*  
oSavedFile.write(b,nStart,nLen); JiXkW%  
n = nLen; * 11|P  
} O]/BNacS  
catch(IOException e) DqQ+8 w  
{ <}vult^  
e.printStackTrace (); #("/ 1N6  
} @An "ClDa  
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return n; Y, ?- []  
} 0=,vdT  
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} ~?BN4ptc  
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/* bq}hj Cy  
**SiteInfoBean.java @71n{9  
*/ Wu\szI"  
package NetFox; #xlT,:_:)  
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public class SiteInfoBean { 3r]m8
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private String sSiteURL; //Site's URL 1638U1  
private String sFilePath; //Saved File's Path >bo_  
private String sFileName; //Saved File's Name {dk%j~w8  
private int nSplitter; //Count of Splited Downloading File tu%!j}3s  
.]IidsgM  
"j<l=l!  
public SiteInfoBean() yH:gFEJ:x  
{//nSplitter的缺省值为5 :I)WSXP9h  
//default value of nSplitter is 5 |oL}c!0vs  
this("","","",5); iFi6,V*PRt  
} 2/coa+Qkv]  
i!U,qV1  
4,yS7l  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) }CoR$
K  
{ .dM|J'`g  
sSiteURL= sURL; ._$tNGI4  
sFilePath = sPath; W ^MF3  
sFileName = sName; ='p&T
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this.nSplitter = nSpiltter; 5VXI/Lw#  
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} ~Ip-@c}'j  
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public String getSSiteURL() /Mg$t6vM  
{ h\@\*Xz<v  
return sSiteURL; S{sJX5R;  
} D^Cpgha  
{okx*]PIc  
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public void setSSiteURL(String value) , '_y@9?I  
{ Xc!0'P0T  
sSiteURL = value; Z fQzA}QD  
} uq~Z  
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!i`HjV0wS  
public String getSFilePath() x)h|!T=B~  
{ :zWI"  
return sFilePath; >&mNC\PA  
} =jWcD{;1I}  
63EwV p/|  
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public void setSFilePath(String value) 9 K.
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{ !T<4em8  
sFilePath = value; U<
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} a*oqhOTQ  
B]""%&! O  
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public String getSFileName() 2D"n#O`y  
{ \@3B%RW0  
return sFileName; ,y'E#_cTgQ  
} 4~bbng  
|lnMT)^D  
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public void setSFileName(String value) orGkS<P  
{ GO|1O|?  
sFileName = value; )Td;2  
} -{^IT`  
S>! YBzm&X  
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public int getNSplitter() YoT<]'  
{ d[p-zn.  
return nSplitter; rKtr&w7X  
} dE`a1H%  
)C@O7m*.4  
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public void setNSplitter(int nCount) D>Ub)i  
{ $P{|^ou3a#  
nSplitter = nCount; K]  
} mw[  
} +kMVl_`V  
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e?V7<7$  
/* yq
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**Utility.java t,f)!D$
 
*/ 4=Wtv/ 3  
package NetFox; u
aX#nn?ws  
" 0:&x n8L  
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public class Utility { YM:;mX5B  
,"@Tm01os  
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public Utility() Xq"_^  
{ N 9.$--X}D  
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!bPsJbIo>  
} Ji#"PE/Pt  
t=K;/1  
//线程睡眠 vLc7RL  
public static void sleep(int nSecond) (F<VcB  
{ 4GiHp7Y&A  
try{ 5q.d$K |  
Thread.sleep(nSecond); o)(N*tC  
} |9Gng`)  
catch(Exception e) z)Yk&;XC  
{ o~_wx  
e.printStackTrace (); B;3lF;3`  
} |SO?UIWp  
} 'R{X
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sW53g$`v  
//日志 H(JgqbFB*  
public static void log(String sMsg) &gNb+z+  
{ nO^m  
System.err.println(sMsg); T;4& ^5n  
} i>]1E^yF  
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7M|!
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public static void log(int sMsg) $RFy9(>  
{ DR d|m
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System.err.println(sMsg); 5`!Bj0Uf  
} ^tw\F7  
} 3!&PI  
o!\Q,  
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/* 'V*ixK8R0  
**TestMethod.java ="k9 y  
*/ =J2cX`  
package NetFox; O!,WH?
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public class TestMethod { x344}\  
MR) *Xh  
3N5un`K7  
public TestMethod() {.D^2mj|  
{ ///xx/weblogic60b2_win.exe n]15 ~GO.  
try{ n!Ic.T3PA  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5);
4(h19-V  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ?yfw3s  
SiteFileFetch fileFetch = new SiteFileFetch(bean); \),DW)  
fileFetch.start(); CQ4MQ<BJ.  
} #:~MtV  
catch(Exception e){e.printStackTrace ();} xrXfLujn%  
I3ZlKI  
%![%wI?  
} N=JZtf/i  
-L.U4x  
![>j`i  
public static void main(String[] args) $$,/F  
{ CTNeh%K;  
new TestMethod(); dGNg[  
} 'e/= !"T  
} "vH>xBR[%  
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