http断点续传简单实现（java)

/* :EJ+#  
**SiteFileFetch.java x=pq-&9>B  
*/ 6Z]* ce<r  
package NetFox; Y,RBTH  
import java.io.*; t4R=$ km  
import java.net.*; +/'3=!oyd  
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+!\$SOaR{  
public class SiteFileFetch extends Thread { R3`!Xj#&M  
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SiteInfoBean siteInfoBean = null; //文件信息Bean _5uzu6:y  
long[] nStartPos; //开始位置 56;lB$)"  
long[] nEndPos; //结束位置 Cb~_{$A  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Q&}`( ]k  
long nFileLength; //文件长度 -&I
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boolean bFirst = true; //是否第一次取文件 R*3x{DNL  
boolean bStop = false; //停止标志 ]mYT!(}  
File tmpFile; //文件下载的临时信息 v)
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DataOutputStream output; //输出到文件的输出流 ZW{pO:-  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） _5 Zhv-7  
public SiteFileFetch(SiteInfoBean bean) throws IOException p}$VBl$'  
{ BUqe~E|I  
siteInfoBean = bean; 8<#X]I_eP+  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); W-ErzX  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 5(R ./  
if(tmpFile.exists ()) u=I\0H  
{ N2[EdOJT_  
bFirst = false; 2fM*6CaS  
read_nPos(); GLrHb3@"N  
} bx`s;r=  
else tn&~~G~#  
{ 8x#SpDI  
nStartPos = new long[bean.getNSplitter()]; 5TqB&GP0  
nEndPos = new long[bean.getNSplitter()]; :QT0[P5O  
} 0l=g$G \%  
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} I]t ",s/j
 
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public void run() #!(OTeL  
{ 6}zargu(;  
//获得文件长度 ,)^4H>~V  
//分割文件 OBp
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//实例FileSplitterFetch BO)K=gl;8  
//启动FileSplitterFetch线程 c@!%.# |y  
//等待子线程返回 ltRvNXx+]  
try{ [(Ss^?AJW  
if(bFirst) FMMQO,BU  
{ .G8+D%%.  
nFileLength = getFileSize(); ANh7`AUuO  
if(nFileLength == -1) {,61V;Bpm  
{ [9dW9[Z+!  
System.err.println("File Length is not known!"); ,$BbJQ5  
} h8OmO5/H  
else if(nFileLength == -2) qP=4D 9 ]  
{ J%]</J  
System.err.println("File is not access!"); L6S!?t.{Yv  
} vDl6TKXcu  
else _P9Th#UAg  
{ ,U':=8  
for(int i=0;i<nStartPos.length;i++) !lf'gW  
{ Sxo9y0K8-  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); oRmz'F  
} =g)|g+[H  
for(int i=0;i<nEndPos.length-1;i++) RS'!>9I  
{ }j9V0`Q  
nEndPos = nStartPos[i+1]; d/oxRzk'L  
} ,ND}T#yTR  
nEndPos[nEndPos.length-1] = nFileLength; +72[*_ <  
} xaiA2  
} gbF^m`A>%+  

}@JPvIE  
4mNg(w=NF  
//启动子线程 v53qpqc  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Ovu!G q  
for(int i=0;i<nStartPos.length;i++) [AgS@^"sf5  
{ 6bj.z  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Fv_rDTo  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), *Xm$w  
nStartPos,nEndPos,i);  {oQ.y  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -:Up$6PR  
fileSplitterFetch.start(); "\0&1C(G  
} ;.*n77Y  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), o ;nw
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); <Sw>5M!j  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", DLMM1 A  
nEndPos = " + nFileLength); rZ}y'A   
// fileSplitterFetch[nPos.length-1].start(); ';<gc5EK  
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=P>c1T1-  
//等待子线程结束 cbsU!8
 
//int count = 0; |-kU]NJFR  
//是否结束while循环 }AdA? :7A  
boolean breakWhile = false; 9[#9cv  
#{97<sU\  
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while(!bStop) Z:51Q  
{ %-u Ra\  
write_nPos();
p) #7K  
Utility.sleep(500); )q#1C]7m*  
breakWhile = true; cO}`PD$i  
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for(int i=0;i<nStartPos.length;i++) X'BFR]cm  
{ ca~nfo  
if(!fileSplitterFetch.bDownOver) t\&u  
{ T
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breakWhile = false; '#JC 6#X   
break; MA9Oi(L)K  
} !8'mIXZ$  
} B[2 qI7D$  
if(breakWhile) qo,uOi
 
break; eRV4XB:  
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//count++; k.UQT^.  
//if(count>4) >SS YYy  
// siteStop(); NFDh!HUm  
} b=Rw=K.  
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System.err.println("文件下载结束！"); CVo2?ZQ  
} zB,Vi-)vH  
catch(Exception e){e.printStackTrace ();} vE4ce  
}
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//获得文件长度 TCb 7-s  
public long getFileSize() Z+# =]Kw)  
{ ^Bkwbj  
int nFileLength = -1; `R\aNgCS}  
try{ S(bYN[U  
URL url = new URL(siteInfoBean.getSSiteURL()); RZKdh}B?\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2h Wtpus  
httpConnection.setRequestProperty("User-Agent","NetFox"); A}./ ;[  
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|ATz<"q>  
int responseCode=httpConnection.getResponseCode(); WX2:c,%:  
if(responseCode>=400) ey icMy`7{  
{ ?ks3K-.4  
processErrorCode(responseCode); #2&DDy)Bf  
return -2; //-2 represent access is error 2@&|/O6_\h  
} RXo!K iQO  
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String sHeader; 1Z. D3@  
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for(int i=1;;i++) ;;A8*\*$  
{ /iz{NulOz*  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); /Mac:;W`  
//Utility.log(in.readLine()); 4<P=wK=a8X  
sHeader=httpConnection.getHeaderFieldKey(i); u1@&o9  
if(sHeader!=null) x:Mh&dq?  
{ -o\o{?t,  
if(sHeader.equals("Content-Length")) '{e9Vh<x  
{ pb>TUKvT&  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 6oh\#v3zV  
break; :K-05$K  
} gd#j{yI/Xf  
} dp&8:jy  
else "'#18&N  
break; H]^hEQ3DT  
} w+,Kpb<x[0  
} ,RP"m#l!\  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();} LIm{Y`XU  
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Utility.log(nFileLength); ](^$5Am  
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return nFileLength; 4Z'/dI`  
} he/WqCZg  
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//保存下载信息（文件指针位置） EISgc {s  
private void write_nPos() 3I}(as{Rp  
{ !]^,!7x,8j  
try{ #pe#(xoI  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ?%QWpKO7X  
output.writeInt(nStartPos.length); ]npsclvJ  
for(int i=0;i<nStartPos.length;i++) .dbZ;`s  
{ O_gr{L}  
// output.writeLong(nPos); 0@O:C
::  
output.writeLong(fileSplitterFetch.nStartPos); >g{w,  
output.writeLong(fileSplitterFetch.nEndPos); b8QQS#q)V  
} }jfOs(Q]  
output.close(); xOKLc!J  
} -[h2fqu1  
catch(IOException e){e.printStackTrace ();} YI877T9>  
catch(Exception e){e.printStackTrace ();}
<l#|
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} }fS`jq;  
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//读取保存的下载信息（文件指针位置） @Rc/^B:  
private void read_nPos() LBcnBo</v  
{ ?j'Nx_RoX  
try{ Ht{Q=w/9  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); <6!;mb ;cX  
int nCount = input.readInt(); ?QJS6i'k  
nStartPos = new long[nCount]; hggP9I:s,  
nEndPos = new long[nCount]; zp4aiMn1F  
for(int i=0;i<nStartPos.length;i++) Rhfx  
{ 6h?v/\  
nStartPos = input.readLong(); )
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nEndPos = input.readLong(); bjR:5@"  
} b6]MJ0do  
input.close(); 3dl#:Si  
} bXiOf#:''  
catch(IOException e){e.printStackTrace ();} k}0Y&cT!rU  
catch(Exception e){e.printStackTrace ();} 3QD+&9{D  
} /s/\5-U7q  
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private void processErrorCode(int nErrorCode) o0Z~9iF&  
{ ep,"@,,  
System.err.println("Error Code : " + nErrorCode); C>MEgGP  
} p%ve1>c  
$;J:kd;<  
'5f6 M^}|2  
//停止文件下载 ;2&ym
)`  
public void siteStop() N=vb*3ECg  
{ _nn\O3TB  
bStop = true; U8>M`e"D  
for(int i=0;i<nStartPos.length;i++) 'joc8o sS  
fileSplitterFetch.splitterStop(); @5=2+ M  
*XCgl*% *  

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} ;ndwVZ~,  
} {:%A  
//负责部分文件的抓取 #Wf9`  
**FileSplitterFetch.java !gyEw1Re7  
*/ ?=},%^  
package NetFox; ~MpcVI_K  
?=FRnpU?  
,UveH` n-  
import java.io.*; aAi"  
import java.net.*; U+4W9zhwo  
b
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public class FileSplitterFetch extends Thread { pm4'2B|)g  
-(;<Q_'s{"  
; *ZiH%q,  
String sURL; //File URL =[ +)T[  
long nStartPos; //File Snippet Start Position -50Nd=1  
long nEndPos; //File Snippet End Position fZ6-ap,u  
int nThreadID; //Thread's ID ,q".d =6  
boolean bDownOver = false; //Downing is over eoGGWW@[
 
boolean bStop = false; //Stop identical yGs:3KI  
FileAccessI fileAccessI = null; //File Access interface jE#&u DfI  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException \'>8 (i~  
{ Rf4}4ixkj  
this.sURL = sURL; #;lB5) oe  
this.nStartPos = nStart; !RPPwvNk4  
this.nEndPos = nEnd; h!!7LPxt  
nThreadID = id; Kqn{q4L  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 -qDM(zR  
} RAs5<US:  
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{[[j.)  
public void run() 0]u=GD%  
{ u,88V@^  
while(nStartPos < nEndPos && !bStop) C4h4W3w  
{ aj|gt  
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try{ {0IC2jE  
URL url = new URL(sURL); M~O$,dof  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 5;:964Et  
httpConnection.setRequestProperty("User-Agent","NetFox"); [$]Kp9YD  
String sProperty = "bytes="+nStartPos+"-"; g-NfZj?  
httpConnection.setRequestProperty("RANGE",sProperty); = a54  
Utility.log(sProperty); `*ml/% \  
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InputStream input = httpConnection.getInputStream(); "3H?_!A9  
//logResponseHead(httpConnection); wc~k4B9"  
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byte[] b = new byte[1024]; :&-j{8p-  
int nRead; |WUm;o4E`U  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ln&9WF\I  
{ 3x6@::s~  
nStartPos += fileAccessI.write(b,0,nRead); AfaoFn+  
//if(nThreadID == 1) Z{p62|+Ck@  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ;
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} {[tx^b  
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Utility.log("Thread " + nThreadID + " is over!"); UPr8Q^wm  
bDownOver = true; g>&b&X&Y_  
//nPos = fileAccessI.write (b,0,nRead); QP={b
+8  
} ,>vI|p,/G*  
catch(Exception e){e.printStackTrace ();} :h!&.FB  
} ;R4qE$u2^  
} JZom#A. dt  
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:WM[[LOaC  
//打印回应的头信息 ns}"[44C}l  
public void logResponseHead(HttpURLConnection con) q*pWx]Y  
{ ><r\ 5`  
for(int i=1;;i++) o8h1  
{ 4)OM58e}  
String header=con.getHeaderFieldKey(i); iO2%$Jw9\  
if(header!=null) /t;Kn m  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); >"%}x{|  
Utility.log(header+" : "+con.getHeaderField(header)); BSc5@;  
else 8^
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break; 863PVce",}  
}
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} TD"w@jBA  
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public void splitterStop() KU5|~1t 4  
{ mvV5Xal  
bStop = true; |.;LI=CT  
} \4FKZ>1+R  
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 1(
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} lRr={ >s  
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]$xN`O4W{  
/* *(*
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**FileAccess.java `a:L%Ex  
*//文件访问(定位，写) dxwH C\"5  
package NetFox; jxdxIkAHZc  
import java.io.*; 7O^'?L<C'  
)gb gsQZ  
7$/%c{o  
public class FileAccessI implements Serializable{ Im0#_ \  
*5Aq\g,n  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ~K-_]*[x  
RandomAccessFile oSavedFile; 4Px  
long nPos; Q?7:XbN  
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public FileAccessI() throws IOException jn/ J-X=  
{ f6O5k8n  
this("",0); VsTa!V^~  
} ,^d!K(xb  
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public FileAccessI(String sName,long nPos) throws IOException %@4/W N  
{ ;~ ,<8  
oSavedFile = new RandomAccessFile(sName,"rw"); >~)IsQ*%  
this.nPos = nPos; mok%TK  
oSavedFile.seek(nPos); U%)m [zAw  
} * U#@M3g.  
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public synchronized int write(byte[] b,int nStart,int nLen) 5Z
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{ 'D1Sm&M2%e  
int n = -1; :!nBTw  
try{ QZ:xG:qyk;  
oSavedFile.write(b,nStart,nLen); 0A.PfqY
i  
n = nLen; u{>_Pb  
} wO&2S-;_K  
catch(IOException e) !v`C-1}70  
{ wEp*j+Mmce  
e.printStackTrace (); mE+  
} Pcox~U/j  
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fNllF,8}  
return n; YLO/J2['  
} g-cC&)0Q  
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} $GcVI;a  
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/* G"._]3CPF  
**SiteInfoBean.java tUR9ti  
*/ {6uhUb  
package NetFox; TA~YCj$  
60`4 _Uy]_  
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public class SiteInfoBean { #FL\9RXy  
Q*h%'oc`  
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private String sSiteURL; //Site's URL SSh=r  
private String sFilePath; //Saved File's Path +&:?*(?Q  
private String sFileName; //Saved File's Name v!b 8_0~u6  
private int nSplitter; //Count of Splited Downloading File K0bh;I  
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public SiteInfoBean() Q[U_ 0O,A9  
{//nSplitter的缺省值为5 |loo^!I  
//default value of nSplitter is 5 Nr(3!-
  
this("","","",5); _/iw=-T  
} >*"6zR2 o  
@uaf&my,P  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 83ajok4E  
{ QoVRZ$!p  
sSiteURL= sURL; FYtf<C+  
sFilePath = sPath; EDkxRfY2/  
sFileName = sName; iNxuQ7~  
this.nSplitter = nSpiltter; 6QC=:_M;  
7KzMa%=  
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} /j0zb&  
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:y!%GJW  
public String getSSiteURL() ]|y]?7  
{ tgX},OU^  
return sSiteURL; J"TM[4^\Y  
} ,@b7N[h  
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public void setSSiteURL(String value) =:;KYuTr  
{ xn)eb#r  
sSiteURL = value; l`}Ag8Q  
} $)fybnY  
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Wveba)"$  
public String getSFilePath() ydyGPZt  
{ L`!M3c@u  
return sFilePath; v-J9N(y"
 
} x`#|8  
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public void setSFilePath(String value) j+>#.22+  
{ sMikTwR/^  
sFilePath = value; O73 /2=1V  
} c T!L+zg  
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public String getSFileName() -q-/0d<l  
{ 27NhYDo  
return sFileName; N{$'-[  
} 5
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X@[)jWs  
{ fmY_T[Q8  
public void setSFileName(String value) 08!pLE  
{ D<m+M@u  
sFileName = value; D=Pv:)*]  
} a V4p0s6ZZ  
u*<G20~A  
K^_Mt!%  
public int getNSplitter() 1YklPMx6  
{ H$/r{gfg^  
return nSplitter; h]#wwJF  
} 7fOk]Yl[  
tv+H4/  
N~%F/`Z<+  
public void setNSplitter(int nCount) ~alC5|wCUQ  
{ gD\ =  
nSplitter = nCount; r9a?Y!(  
} {[&_)AW6m%  
} Z{|U!tn
 
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UBUZ}ZIbN  
/* pzMli^  
**Utility.java y'9 bs  
*/ &m'ttUG?  
package NetFox; ?d -$lI  
dtdz!'q)Y  
|^ao,3h#  
public class Utility { .i7bI2^  
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public Utility() 5 E%dF9q  
{ |Ki\Q3O1  
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} l1RpG"  
8qEK6-  
//线程睡眠 8G>;X;W  
public static void sleep(int nSecond) Ng6(2
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{ \?bp^BrI  
try{ (]Z$mv!  
Thread.sleep(nSecond); [S}o[v\  
} 0ang^v;q  
catch(Exception e) %EZG2JjO)  
{ ?]fd g;?@  
e.printStackTrace (); !~{AF|2f  
} .Jt&6N  
} =Of!1TR(  
WheJ 7~  
//日志 b ;Vy=f  
public static void log(String sMsg) $?l?  
{ sW":~=H  
System.err.println(sMsg); O MEPF2:  
} a;a2x .<  
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ccWz,[  
public static void log(int sMsg) p2|BbC\N  
{ EH'?wh|Yp  
System.err.println(sMsg); "e4hPY#  
} %}U-g"I  
} {=AK|  
iB Ld*B|#K  
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/* J^@0Ff;=5^  
**TestMethod.java V}l>p?  
*/ U20G{%%  
package NetFox; $lj1924?^  
u3 mTsq!  
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public class TestMethod { UGy~Ecv  
vG'JMzAm  
g+ik`q(ge  
public TestMethod() y[*Bw)F\N  
{ ///xx/weblogic60b2_win.exe zS*X9|p  
try{ Wmp,,H  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ^/Id!Y7  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); eD0Rv0BV^  
SiteFileFetch fileFetch = new SiteFileFetch(bean); lO-:[@  
fileFetch.start(); *pMgjr  
} 9w -t9X>X  
catch(Exception e){e.printStackTrace ();} :@TfhQV_=Q  
t@Qs&DZ7k  
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} &)Fp  
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xzFV]  
public static void main(String[] args) a.a5qwG  
{ ~M 6^%  
new TestMethod(); Q"UQv<  
} c~0YIk>]  
} :^DuB_  
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