http断点续传简单实现（java)

/* qM:)daS1w  
**SiteFileFetch.java j5Wx*~@(  
*/ 'lRHdD}s  
package NetFox; _TN$c  
import java.io.*; &|{,4V0%A  
import java.net.*; c+)|o!d  
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public class SiteFileFetch extends Thread { MW[ 4^  
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SiteInfoBean siteInfoBean = null; //文件信息Bean "!/_h >  
long[] nStartPos; //开始位置 re7\nZ<\|  
long[] nEndPos; //结束位置 iM/0Yp-v'>  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Nt^&YE7d:  
long nFileLength; //文件长度 >(6\ C  
boolean bFirst = true; //是否第一次取文件 rnhf(K.{3  
boolean bStop = false; //停止标志 75}u D  
File tmpFile; //文件下载的临时信息 ?{z${ bD  
DataOutputStream output; //输出到文件的输出流 0(g MR  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） z%dlajYm:  
public SiteFileFetch(SiteInfoBean bean) throws IOException U?^|>cMr  
{ P_g0G#`4  
siteInfoBean = bean; T\s#-f[x  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ^-;Z8M  
if(tmpFile.exists ()) }7
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{ $)7f%II  
bFirst = false; z+D,:!yF  
read_nPos(); 5'-9?-S"  
} bfI -!,  
else u R%R]X  
{ }0nB'0|y  
nStartPos = new long[bean.getNSplitter()]; _r5Ild@n  
nEndPos = new long[bean.getNSplitter()]; (@o />T  
} }qdJ8K  
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} # +]! u%n  
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public void run() nkj'AH"2  
{ 842+KLS  
//获得文件长度 2b,TkG8K  
//分割文件 :RO:k|g  
//实例FileSplitterFetch ?E_p,#9j)  
//启动FileSplitterFetch线程 RTY4%6]O  
//等待子线程返回 7%!KAtc  
try{ hPpXB:(-0  
if(bFirst) ;k%sKVP  
{ HPdwx V  
nFileLength = getFileSize(); y8S6ZtA}2  
if(nFileLength == -1) q<uLBaL_]r  
{ <
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System.err.println("File Length is not known!"); +<WT$ddK=5  
} KR(ftG'  
else if(nFileLength == -2) d>98 E9  
{ BF[?* b  
System.err.println("File is not access!"); S|4/C  
} ~%K(ou=2  
else % P)}(e6y  
{ #=#$b_6*  
for(int i=0;i<nStartPos.length;i++) gpvj'Ri7V  
{ xa0%;nFKe  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); I3$vw7}5Y  
} WA\f`SRF  
for(int i=0;i<nEndPos.length-1;i++) +i!M[  
{ B[|/wHMsT}  
nEndPos = nStartPos[i+1]; $K fk
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} !jq6cND  
nEndPos[nEndPos.length-1] = nFileLength; 3i}B\ {  
} F_Cz  
} _-\{k
J  

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TC#B^m`'p  
//启动子线程 2U+p@}cQUA  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; B"zg85 e  
for(int i=0;i<nStartPos.length;i++) 3 v$
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{ #}yFHM?i  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7 ~8Fs@  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), %9Fg1LH42r  
nStartPos,nEndPos,i); =e/4Gs0*  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 0U*"OSpF  
fileSplitterFetch.start(); PQ1NQy8  
} bK1`a{  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), \bSHBTK  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); kDa#yN\  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", +rP<m  
nEndPos = " + nFileLength); :8wF0n-'  
// fileSplitterFetch[nPos.length-1].start(); !`=?<Fl  
6e|5qKr  
$*-L8An?  
//等待子线程结束 :P"Gym  
//int count = 0; rO%+)M$A  
//是否结束while循环 *~^^A9C8  
boolean breakWhile = false; tp2 _OQAQ  
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while(!bStop) <F & hfy  
{ ;_&L^)~P$  
write_nPos(); &L~rq)r/&  
Utility.sleep(500); 3*JybMo"  
breakWhile = true; >G~;2K[  
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for(int i=0;i<nStartPos.length;i++) E_rC"_Zte  
{ C8q-gP[  
if(!fileSplitterFetch.bDownOver) :+!b8[?Z  
{ 6D(m8  
breakWhile = false; ,sl.:C4  
break; 6 74X)hB  
} Qf]!K6eR
 
} FQ)Ekss~C  
if(breakWhile) ".<p R} qp  
break; e'&{KD,-T  
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//count++; lM,:c.R  
//if(count>4) 5xUPqW%3  
// siteStop(); y<(.,Nb8  
} ;f~'7RKy!G  
%TgM-F,8  
9Bw"VN]W  
System.err.println("文件下载结束！"); _Z2)e*(  
} ?3N86Qj  
catch(Exception e){e.printStackTrace ();} P@?CQvMx  
} ':$a6f &T  
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\RO S
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//获得文件长度 >WX'oP(<  
public long getFileSize() mIodD)?{  
{ ~vFo 0k(  
int nFileLength = -1; a$8?0`(  
try{ b] V=wZ o  
URL url = new URL(siteInfoBean.getSSiteURL()); _*I6O$/>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 'WCTjTob/  
httpConnection.setRequestProperty("User-Agent","NetFox"); B=`!  
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:tG5~sK  
int responseCode=httpConnection.getResponseCode(); Q.\ovk~,a  
if(responseCode>=400) xRN$cZC  
{ I5?LD=tt  
processErrorCode(responseCode); `,[c??h  
return -2; //-2 represent access is error 0in6z  
} JN)t'm[kyE  
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String sHeader; xpwzzO*U  
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for(int i=1;;i++) $*R9LPpk+  
{ .Oh$sma1  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); kq-RM#Dj:  
//Utility.log(in.readLine()); E@KK\m \e  
sHeader=httpConnection.getHeaderFieldKey(i); lUd
,-  
if(sHeader!=null) hd-ds~ve  
{ "(qO}&b>  
if(sHeader.equals("Content-Length")) my6T@0R  
{ ]du~V?N   
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); t:7jlD!d  
break; WgB,,L,  
} -bF+uCfba  
} dM$S|,H  
else dD%m=x  
break; 6}$cDk`dz  
} r_m&Jl@4  
} d+'+z %s%  
catch(IOException e){e.printStackTrace ();} *TkABUL  
catch(Exception e){e.printStackTrace ();} Q23y.^W%c  
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Utility.log(nFileLength); NYeg,{q  
,<7f5qg"'  
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return nFileLength; oL;/Qan  
} Tw5BvB1  
}s[/b"%y  
76/%Py|  
//保存下载信息（文件指针位置） , +^db)  
private void write_nPos() x!+a,+G  
{ -j,o:ng0  
try{ }1wuH  
output = new DataOutputStream(new FileOutputStream(tmpFile)); I_rVeMw=  
output.writeInt(nStartPos.length); Fz% n!d  
for(int i=0;i<nStartPos.length;i++) _?"J.
i  
{ yrX]w3kr%  
// output.writeLong(nPos); Lsdu:+-  
output.writeLong(fileSplitterFetch.nStartPos); j>iM(8`t1  
output.writeLong(fileSplitterFetch.nEndPos); T5h[{J^  
} =Sq7U^(>  
output.close(); y8@!2O4  
} sBwgl9  
catch(IOException e){e.printStackTrace ();} Ih0GzyU*4  
catch(Exception e){e.printStackTrace ();}  ^8iy(  
} ITV}f#  
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vY6
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//读取保存的下载信息（文件指针位置） xjpW<-)MLf  
private void read_nPos() By9/tB  
{ :`K;0`C+  
try{ DH%X+r  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); J98K:SAR  
int nCount = input.readInt(); ?0x;L/d])  
nStartPos = new long[nCount]; OZ6%AUot  
nEndPos = new long[nCount]; z$NLFJvy_-  
for(int i=0;i<nStartPos.length;i++) tj3p71%  
{ wHmEt ORo  
nStartPos = input.readLong(); R)=<q]Ms  
nEndPos = input.readLong(); 79v&6Io  
} K5$ y  
input.close(); !FO)||'[  
} P_gQ-pF.  
catch(IOException e){e.printStackTrace ();} !ktr|9Bl  
catch(Exception e){e.printStackTrace ();} ~>n<b1}W  
} =6$(m}(74  
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private void processErrorCode(int nErrorCode) `6/7},"9t  
{ fCKcv |  
System.err.println("Error Code : " + nErrorCode); *uIHa"  
} rZEu@6
3  
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d  
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//停止文件下载 <+a\'Xc  
public void siteStop() e/6oC~#]  
{ 3-05y!vbcE  
bStop = true; +vP1DXtj(  
for(int i=0;i<nStartPos.length;i++) w%ForDB>P  
fileSplitterFetch.splitterStop(); D+V^nCcx%  
8Y9mB#X  
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} L2$%h1  
} E=y
#

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//负责部分文件的抓取 M@8(h=  
**FileSplitterFetch.java }Y[.h=X  
*/ "elh~K  
package NetFox; vv u((b  
{9)f~EbM!  
=k'dbcfO$9  
import java.io.*; D|xSO~M5  
import java.net.*; pnD#RvmW2e  
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public class FileSplitterFetch extends Thread { Y9WH%  
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?}y7S]B FI  
String sURL; //File URL ()rDM@  
long nStartPos; //File Snippet Start Position | 8AH_Fk  
long nEndPos; //File Snippet End Position AA66^/t  
int nThreadID; //Thread's ID p7*\]HyE)  
boolean bDownOver = false; //Downing is over &"BKue~q@p  
boolean bStop = false; //Stop identical ,FTF@h-Cs  
FileAccessI fileAccessI = null; //File Access interface */1z=  
&~j"3G;e  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException * .e^s3q$  
{ dG| iA]  
this.sURL = sURL; a
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this.nStartPos = nStart; M1^pW63  
this.nEndPos = nEnd; qAm%h\  
nThreadID = id; 0zd1:*KR,  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 i@2?5U>h  
} |y]#-T?)t  
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public void run() b;yhgdFx  
{ "0 v]O~s  
while(nStartPos < nEndPos && !bStop) u@o3p*bQ  
{ ,Zdc  
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try{ {DpZg",H-  
URL url = new URL(sURL); i_MDLS>-  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); p\(%bO
 
httpConnection.setRequestProperty("User-Agent","NetFox"); QKVZ![Y!s  
String sProperty = "bytes="+nStartPos+"-"; M4QMD;Ez  
httpConnection.setRequestProperty("RANGE",sProperty); C}Khh`8@5.  
Utility.log(sProperty); &t4j px  
mJT7e  
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InputStream input = httpConnection.getInputStream(); Sh"} c2  
//logResponseHead(httpConnection); w,\Ua&>4  
"^u|vCqw  
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byte[] b = new byte[1024]; k -SUp8}g  
int nRead; Dr;@)  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) w}'E]y2.  
{
xQN](OKG  
nStartPos += fileAccessI.write(b,0,nRead); |h.he_B+7  
//if(nThreadID == 1) XpM#0hm  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `+<5QtD  
} pdE=9l'  
7_JK2  
)q#b^( v  
Utility.log("Thread " + nThreadID + " is over!"); %1#5 7-  
bDownOver = true; hX;xbl  
//nPos = fileAccessI.write (b,0,nRead); KB-7]H  
} VQX#P<  
catch(Exception e){e.printStackTrace ();} 6OVAsmE  
} $ @^n3ZQ4  
} %DiZ&}^Ck  
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39u!j|VH  
//打印回应的头信息 utQ_!3u  
public void logResponseHead(HttpURLConnection con) s,0,w--=  
{ e'u9 SpJ  
for(int i=1;;i++) _$1W:!f4  
{ ><$hFrR!  
String header=con.getHeaderFieldKey(i); f~E'0f_  
if(header!=null) M'*
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); gllXJM^ -  
Utility.log(header+" : "+con.getHeaderField(header)); = uOFaZ4  
else 0`_Gj{:L  
break; 75{QBlf<  
} W$,c]/u|  
} B&tl6?7h  
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public void splitterStop() sR#( \  
{ 1(C%/g#"  
bStop = true; 8TuOf(qE  
} Z,ag5 w`]L  
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} N2C^'dFj  
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@v|_APy#  
/* O"Ar3>  
**FileAccess.java 0e3aWn  
*//文件访问(定位，写) C#(4>'  
package NetFox; !k&<  
import java.io.*; xAsbP$J:  
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#Jg)HU9  
public class FileAccessI implements Serializable{ AWGeK-^  
pi+m`O   
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 (0^u  
RandomAccessFile oSavedFile; :)bm+xWFF  
long nPos; is`le}$^y  
5y@JMQSO  

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public FileAccessI() throws IOException 3<?#*z4]_  
{ *y7^4I-J  
this("",0); h@l5MH=|%  
} ]Y:|%rvVH  
/)6<`S(  
3%'$AM}+s  
public FileAccessI(String sName,long nPos) throws IOException )j!22tlL  
{ iYBs )  
oSavedFile = new RandomAccessFile(sName,"rw"); |odl~juU  
this.nPos = nPos; O']-<E`1k  
oSavedFile.seek(nPos); p ^T0(\1  
} $--W,ov5j  
"w=.2A:q  

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public synchronized int write(byte[] b,int nStart,int nLen) I%;xMtY1o  
{ P)ZGNtO9fG  
int n = -1; K5'@$Km  
try{ W~FcU+a  
oSavedFile.write(b,nStart,nLen); .\qZkk}2l  
n = nLen; uQ. m[y  
} 7zT]\AnO  
catch(IOException e) %6HDLG6@^}  
{ r6QNs1f~.  
e.printStackTrace (); vY:A7yGW  
}  h9RG?r1  

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return n; U!TFFkX[  
} ]xbR:CYJ  
}5FdX3YR  
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} C4]vq+  
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^
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/* p'ukV(B  
**SiteInfoBean.java gVl%:Ra%  
*/ D?;$:D"  
package NetFox; Jah~h44&  
*h$Z:p-g  
aB+Ux< -  
public class SiteInfoBean { Mq8jPjL  
NAlYfbp  
+t})tDPXw  
private String sSiteURL; //Site's URL a3sXl+$D@  
private String sFilePath; //Saved File's Path a>G|t5w  
private String sFileName; //Saved File's Name s-~Tf|  
private int nSplitter; //Count of Splited Downloading File -!k"*P  
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public SiteInfoBean() wZ5+ H%x  
{//nSplitter的缺省值为5 |#Z:v1]"  
//default value of nSplitter is 5 '/J}T -,Z  
this("","","",5); a$l  
} +K])&}Dw  
inBBU[Sl  
D}r,t_]Eb  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) bT2b)nf  
{ 2r^|  
sSiteURL= sURL; hqmKUlo  
sFilePath = sPath; ]2+7?QL,  
sFileName = sName; |Qo;=~7  
this.nSplitter = nSpiltter; mvyqCOp0  

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4jfkCU  
} 6V KsX+sd  
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MD%_Z/NL  
public String getSSiteURL() t-)C0<  
{ l}
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return sSiteURL; .;8T*  
} ]'3e#Cqeh  
E9!u|&$S  
J]^)vxm3  
public void setSSiteURL(String value) Ph'*s{  
{ ~q 0)+'  
sSiteURL = value; =X'i^Q  
} y2bL!Y<s9  
!ZPa
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A
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public String getSFilePath() *tC]Z&5  
{ &.,ZU\`zT  
return sFilePath; >jD,%
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} |W];8  
n[H3b}  
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public void setSFilePath(String value) eQbDs_  
{ q90eB6G0g  
sFilePath = value; Mhc!v, D$  
} ~pWbD~aeg  
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public String getSFileName() AL74q[>  
{ .H {  
return sFileName; FIG3P))  
} s-!Bpr16o0  
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F:"<4hiA"  
public void setSFileName(String value) D<B/oSy  
{ NHG+l)y:  
sFileName = value; vtM!?#  
} @-|{qP=Dy  
+YVnA?r?  
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public int getNSplitter() :biM}L  
{ }u8o*P|,  
return nSplitter; ^tc2?T  
} 5}@6euT5$  
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;3wj(o0  
public void setNSplitter(int nCount) P#m/b<  
{ # Y/.%ch.  
nSplitter = nCount; FT
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} xs_l+/cZ  
} zA4m !l*eM  
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/* ;gfY_MXnF  
**Utility.java JDrh-6Zgj  
*/ RLBjl%Q>  
package NetFox; PYX]ld.E  
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a"uO0LOb  
public class Utility { JfS:K'  
SV*h9LL  
~?TG
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public Utility() 7714}%Z  
{ Ta^l1]9.*  
chv0\k"'  
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} *vqlY[2Ax  
F[uy'~;@  
//线程睡眠 |y=;#A  
public static void sleep(int nSecond) U9GmkXRix  
{ eV$pza  
try{ Ej\EuX  
Thread.sleep(nSecond); # ~SuL3  
} ,b!!h]t  
catch(Exception e) D.elE:  
{ wmbjL=f Ia  
e.printStackTrace (); yDh(4w-~gk  
} PI@/jh  
} Bwv@D4bii  
7 \)OWp  
//日志 NfqJ>[}I+  
public static void log(String sMsg)
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{ P[{qp8(g  
System.err.println(sMsg); ns`|G;1vv  
} oo sbf#V  
_):V7Zv  
Pl(+&k`}  
public static void log(int sMsg) n4
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{ [C 1o9c!  
System.err.println(sMsg); ^M36=~j  
} 0ant0<  
} Fr/3Qp@S  
? ->:,I=<~  
dm;H0v+Y'  
/* J!r,ktO^U?  
**TestMethod.java ivL}\~L  
*/ P{2V@ <}  
package NetFox; o|#Mq"od  
PR rf$& u  
8`Wj 1 ,q  
public class TestMethod { V?"X0>]0  
v"'Co6fw  
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public TestMethod() :.5l9Ci4  
{ ///xx/weblogic60b2_win.exe >'IFr9&3  
try{ hm#S4/=#  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); #Hm*<s.  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); @pq#?  
SiteFileFetch fileFetch = new SiteFileFetch(bean); *xm(K+j  
fileFetch.start(); *=UxX ]0y  
} Pp-\#WJ  
catch(Exception e){e.printStackTrace ();} U^jxKBq^  
Cw`8[)=}o  
)X*?M?~\  
} p0Cp\.  
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aRFLh  
public static void main(String[] args)  !]]QbB  
{ 4u}"ng   
new TestMethod(); |GPR3%9  
} 27mGX\T  
} {z)&=v@  
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