http断点续传简单实现（java)

/* j&a\ K}U!  
**SiteFileFetch.java >#l:
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*/ c|aX4=Z  
package NetFox; W(4$.uZ)  
import java.io.*; g.%} +5  
import java.net.*; s3Zt)xQ3  
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public class SiteFileFetch extends Thread { 7I&o  
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SiteInfoBean siteInfoBean = null; //文件信息Bean H<<t^,E^.t  
long[] nStartPos; //开始位置 mTUoFXX[  
long[] nEndPos; //结束位置 &=n/h5e0t&  
FileSplitterFetch[] fileSplitterFetch; //子线程对象
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long nFileLength; //文件长度 XK@&$~iA3  
boolean bFirst = true; //是否第一次取文件 3RvDX p  
boolean bStop = false; //停止标志 mv~?1aIKD  
File tmpFile; //文件下载的临时信息 zb"4_L@m2  
DataOutputStream output; //输出到文件的输出流 )rAJ>;  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） q+p}U}L= k  
public SiteFileFetch(SiteInfoBean bean) throws IOException Gr/}&+S  
{ 2QAP$f0Ln  
siteInfoBean = bean; #-+Q]}fB4  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); yZgWFf.X  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); EStui>ho  
if(tmpFile.exists ()) xDH#K0-#L  
{ j3N d4#  
bFirst = false; N|>JLZ>  
read_nPos(); .QZjJ9pvK  
} yE,qLiH  
else ,c?( |tF  
{ >$-YNZA   
nStartPos = new long[bean.getNSplitter()]; 4cPZGZ{U  
nEndPos = new long[bean.getNSplitter()]; q
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} OgC,oj,!/  
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} :b %2qBv  
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public void run() Cc%{e9e*  
{ @H4]Gp ]  
//获得文件长度 G `!A#As  
//分割文件 b6Z3(!] ]  
//实例FileSplitterFetch |#<z\u }  
//启动FileSplitterFetch线程 ` V [4  
//等待子线程返回 C,$o+q*)W9  
try{ w%iwxo  
if(bFirst) `sso Wn4  
{ W}3%BWn  
nFileLength = getFileSize(); } eHxw+.  
if(nFileLength == -1) #Ktk["6  
{ :3 Hz!iZM  
System.err.println("File Length is not known!"); 2PRiiL@  
} d4^x,hzV  
else if(nFileLength == -2) :3D6OBkB  
{ YG:^gi  
System.err.println("File is not access!"); (Sgsy^|N  
} z~~pH9=c2  
else &p_iAMn:9  
{ n^l*oEl  
for(int i=0;i<nStartPos.length;i++) )`'a1y|  
{ 8M,@Mbn  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); )R'%SLw  
} bfZt<-  
for(int i=0;i<nEndPos.length-1;i++) ~]d9 J  
{ JA9NTu(  
nEndPos = nStartPos[i+1]; k+P3z&e  
} (hZNWQ0  
nEndPos[nEndPos.length-1] = nFileLength; s5mJ -  
} 3F!)7  
} *c/V('D/  
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//启动子线程 \<T7EV.  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; H?Q--pG8  
for(int i=0;i<nStartPos.length;i++) hE`d@  
{ !z4I-a  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ]a&riPh"  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), zx2`0%Q  
nStartPos,nEndPos,i); K\;4;6g  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 7.ein:M|CB  
fileSplitterFetch.start(); Wex2Fd?DO  
} ED79a:  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), U!c+i#:t  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); -.MJ3  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", oi,KA  
nEndPos = " + nFileLength);  1hi,&h  
// fileSplitterFetch[nPos.length-1].start(); glU9A39qx?  
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//等待子线程结束 <a -a~  
//int count = 0; (GL'm[V  
//是否结束while循环 6|f8DX%3V  
boolean breakWhile = false; C R?}*  
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while(!bStop) -=8f*K[W  
{ \ctzv``/n  
write_nPos(); lemV&$WN|  
Utility.sleep(500); XXA'B{@Y)  
breakWhile = true; aZ\Z7(  
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for(int i=0;i<nStartPos.length;i++) uE(5q!/  
{  +@f  
if(!fileSplitterFetch.bDownOver) Q$]1juqg  
{ GBRiU&D  
breakWhile = false; /|UbYe,  
break; DBcR1c&<H  
}
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} 047PlS  
if(breakWhile) Vn{;8hZ:a  
break; ^OIo  
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//count++; OGJrwl  
//if(count>4) w_@{v wM$A  
// siteStop(); qk3~]</  
} .-& =\}^2l  
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System.err.println("文件下载结束！"); NopfL  
} {cLWum[SY  
catch(Exception e){e.printStackTrace ();} Viw,YkC  
} Je9Z:s[  
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c1+z(NQ3  
//获得文件长度 iiJT%Zq`#  
public long getFileSize() y $uq`FW  
{ l$c/!V[3  
int nFileLength = -1; iWr #H  
try{ ;Wk3>\nT-  
URL url = new URL(siteInfoBean.getSSiteURL()); 6]<yR> '  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); +`Nu0y!rj  
httpConnection.setRequestProperty("User-Agent","NetFox"); C\BKdx5;  
y
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int responseCode=httpConnection.getResponseCode(); O_th/hl  
if(responseCode>=400) VbJE zl  
{ S[
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processErrorCode(responseCode); ip{b*@K  
return -2; //-2 represent access is error CW8YNJ'  
} AU%Yr6  
5? Y(FhnIC  
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String sHeader; :]Om4Q\-#  
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for(int i=1;;i++) z~p!7q&g  
{ 40].:9VG  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); udr|6EjD.  
//Utility.log(in.readLine()); s/11TgJ  
sHeader=httpConnection.getHeaderFieldKey(i); ,d_rK\J  
if(sHeader!=null) N!dBF t"  
{ $qZ6i  
if(sHeader.equals("Content-Length")) 9yTkZ`M28  
{ =1|p$@L`%  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 55<!H-zt  
break; f8r7SFwUv  
} +/mCYI  
} <^KW7M}w*c  
else @RuMo"js  
break; 3%o}3.P,:@  
} i-4L{T\K  
} y,n.(?!*  
catch(IOException e){e.printStackTrace ();} xpuTh"ED  
catch(Exception e){e.printStackTrace ();} `#`C.:/n  
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Utility.log(nFileLength); 3jJV5J'"  
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return nFileLength; -}oH],C  
} ]q
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//保存下载信息（文件指针位置） R!X+-  
private void write_nPos() gCkR$.-E  
{ ZDI?"dt{  
try{ O6b+eS  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ?LU>2!jN  
output.writeInt(nStartPos.length); FrLv%tK|  
for(int i=0;i<nStartPos.length;i++) UEYJd&n0CB  
{ C;U4`0=8  
// output.writeLong(nPos); 3syA$0TZt  
output.writeLong(fileSplitterFetch.nStartPos); a;~< iB;3"  
output.writeLong(fileSplitterFetch.nEndPos); /#eS3`48  
} "66#F  
output.close(); &P35\q   
} yn(bW\  
catch(IOException e){e.printStackTrace ();} }>621L3 -  
catch(Exception e){e.printStackTrace ();} +N2ILE8[<  
} g@/}SJh/>  
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xy&*s\=:  
//读取保存的下载信息（文件指针位置） wzoT!-_X  
private void read_nPos() Rd]<591  
{ NzM,0q  
try{ L %ifl:K  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ^4\0,>  
int nCount = input.readInt(); e(b$L
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nStartPos = new long[nCount]; .V_5q:tu  
nEndPos = new long[nCount]; Z:x`][vg  
for(int i=0;i<nStartPos.length;i++) b~YIaD[Z  
{ OBF-U]?Y  
nStartPos = input.readLong(); toOdL0hCe  
nEndPos = input.readLong(); hV) `e"r\s  
} y )<+?@sP  
input.close(); SXJjagAoML  
} 7,
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catch(IOException e){e.printStackTrace ();} )g3c-W=  
catch(Exception e){e.printStackTrace ();} fN<Y3^i"  
} N0\<B-8+,>  
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private void processErrorCode(int nErrorCode) Q:y'G9b  
{ "<)Jso|  
System.err.println("Error Code : " + nErrorCode); o^owv(  
} m&(qr5>b  
v|]"uPxH?  
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//停止文件下载 q3K}2g  
public void siteStop() mC(YO y  
{ Up_"qD6  
bStop = true; T;PLUjp}  
for(int i=0;i<nStartPos.length;i++) A>FWvlLw'm  
fileSplitterFetch.splitterStop(); N Mx:Jh-YN  
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} %AWc`D  
} mZM7 4!4X  
//负责部分文件的抓取 ]TcQGW@'  
**FileSplitterFetch.java @*UV|$~(Q  
*/ 4)'U!jSb  
package NetFox; itc\wn  
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import java.io.*; Xi\c>eALO  
import java.net.*; =WZ@{z9J  
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public class FileSplitterFetch extends Thread { inK;n  
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String sURL; //File URL d 792#Dc  
long nStartPos; //File Snippet Start Position C'Y2kb  
long nEndPos; //File Snippet End Position <Kl$ek8  
int nThreadID; //Thread's ID zE/\2F$  
boolean bDownOver = false; //Downing is over NN5Ejr,  
boolean bStop = false; //Stop identical kh#fUAt  
FileAccessI fileAccessI = null; //File Access interface fl2XI=[v4  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException fWi/mK3c  
{ V s=o@  
this.sURL = sURL; M1*bT@6  
this.nStartPos = nStart; %9S0!h\  
this.nEndPos = nEnd; M#m;jJqON  
nThreadID = id; N0NFgW;  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 "J+4  
} %so{'rQl  
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public void run() r}D#(G$  
{ Jo~fri([%Q  
while(nStartPos < nEndPos && !bStop) ]bpgsW:Xu  
{ yq^Ma  
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try{ {0-rnSjC  
URL url = new URL(sURL); x)eoz2E1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); MPw?HpM  
httpConnection.setRequestProperty("User-Agent","NetFox"); _jgtZ  
String sProperty = "bytes="+nStartPos+"-"; $7i[7S4  
httpConnection.setRequestProperty("RANGE",sProperty); 3Z&!zSK^  
Utility.log(sProperty); <dr2 bz  
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InputStream input = httpConnection.getInputStream(); IvI..#EzG  
//logResponseHead(httpConnection); \/V#
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byte[] b = new byte[1024]; }@tgc?CD  
int nRead; jh`[Y7RJO  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) uhp.Yv@c  
{ ?.H]Y&XF  
nStartPos += fileAccessI.write(b,0,nRead); ={N1j<%fh  
//if(nThreadID == 1) .V3e>8gw3  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); W}MN-0  
} ?A*!rW:l;  
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',LC!^:~Nw  
Utility.log("Thread " + nThreadID + " is over!"); ?#z<<FR  
bDownOver = true; ._`rh  
//nPos = fileAccessI.write (b,0,nRead); &oy')\H  
} oVPr`]  
catch(Exception e){e.printStackTrace ();} w1aoEo"S  
} ylQj2B,CB  
} c/v|e&q  
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//打印回应的头信息 g-"GZi  
public void logResponseHead(HttpURLConnection con) c$tX3ug6I  
{ :XG~AR/  
for(int i=1;;i++) 5/7(>ivn  
{ m
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String header=con.getHeaderFieldKey(i); 0(:SEiz6s  
if(header!=null) FOMJRq  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); vZ.<OD4  
Utility.log(header+" : "+con.getHeaderField(header)); x-%RRm<V  
else ftl?x'P%  
break; M6Np!0G  
} e"NP]_vh,  
} #Nco|v  
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public void splitterStop() uZ\+{j=  
{ Vp|?R65S*  
bStop = true; n\JI7A}  
} 2l^_OrE!  
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} HTGLFY(&  
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/* `8RKpZv&  
**FileAccess.java U,;796h  
*//文件访问(定位，写) 4nh=Dq[  
package NetFox; fFr9]  
import java.io.*; vlE]RB  
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public class FileAccessI implements Serializable{ "*F`,I3  
~QxW^DGa7]  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 B%MdJD>  
RandomAccessFile oSavedFile; pq&[cA_w  
long nPos; c1jRj=\  
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public FileAccessI() throws IOException tH.L_< N  
{ QeuM',6R  
this("",0); =|ODa/2p  
} [3nWxFz$R  
{B4qeG5  
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public FileAccessI(String sName,long nPos) throws IOException hd~#I<8;2  
{ vO~Tx  
oSavedFile = new RandomAccessFile(sName,"rw"); CEc(2q+%i  
this.nPos = nPos; ]77f`<q<}!  
oSavedFile.seek(nPos); [WG\wj.  
} *qk7e[IP  
m6n%?8t  
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public synchronized int write(byte[] b,int nStart,int nLen) :-Jryi
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{ /W BmR R  
int n = -1; QDJ "X  
try{  QSY>8P  
oSavedFile.write(b,nStart,nLen); $/IFSB9  
n = nLen; +,LWyvc'  
} 4_U
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catch(IOException e) dgoAaS2M  
{ OoH-E.lp  
e.printStackTrace (); sVw:d_ E  
} !
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return n; H)7v$A,5%  
}  ID,_0b  
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} T>rmm7F  
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/* % _E?3  
**SiteInfoBean.java ~o"=4q`>  
*/ d-+jb<C&  
package NetFox; 3-{BXht)  
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public class SiteInfoBean { b&&l  
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private String sSiteURL; //Site's URL 3,{eH6,O7M  
private String sFilePath; //Saved File's Path  ,S=[#  
private String sFileName; //Saved File's Name rD SYR\cg  
private int nSplitter; //Count of Splited Downloading File 9|Jv>Ur=)2  
&TQ~!ZMOR"  
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public SiteInfoBean() Z6i~Dy3  
{//nSplitter的缺省值为5 PD.$a-t  
//default value of nSplitter is 5 S,AxrQc  
this("","","",5); \j62"

  
} "N6HX*  
/u4RZ|&as  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 3rH}/`d4  
{ @GQfBV|3  
sSiteURL= sURL; I\k<PglRA  
sFilePath = sPath; %N<5ST>(  
sFileName = sName; `M6"=)twu  
this.nSplitter = nSpiltter; >aO.a[AM  
:QGo -,6-  
tS
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} W?
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7UMZs7L$  
9Sxr9FLW~  
public String getSSiteURL() cE 'LE1DK  
{ <Q9l'u]3$c  
return sSiteURL; _90D4kGU  
} kWZY+jyt P  
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public void setSSiteURL(String value) $ItmYj.m  
{ D0FX"B
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sSiteURL = value; 3P2{M}WIl  
} P|$n   
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public String getSFilePath() M8X6!"B$Y  
{ {f#QZS!E  
return sFilePath; I$t8Ko._"  
} AF{uFna  
<.n,:ir  
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public void setSFilePath(String value) r
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{ :kR>wX  
sFilePath = value; c#{lXS^  
} =6Ok4Z  
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public String getSFileName() >^jBE''  
{ $
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return sFileName; l'EO@D/M  
} ]i.N'O<p  
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public void setSFileName(String value) 9m)$^U>oz  
{ Hp=BnN  
sFileName = value; -a)1L'R  
} A r]*?:4y[  
>fXtu:C-!J  
qKfUm:7Q_  
public int getNSplitter() eavn.I8J  
{ Ra|P5  
return nSplitter; 6^LXctW.  
} ):G%o  
O3o^%0  
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public void setNSplitter(int nCount) kJ5z['4?  
{ ^^"zjl*^  
nSplitter = nCount; ~-A"j\gi"  
} UF!qp  
} d*d:-f~q  
3O2G+G2  
rH`\UZ{cc  
/* prj(  
**Utility.java [n[dr@J7v  
*/ i;1pw_K  
package NetFox; @FN|=
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public class Utility { B8Fb$  
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public Utility() w UxFE=ia  
{ q* R}yt5  
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+ kKanm[!v  
} n\((#<&
 
v@%4i
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//线程睡眠 t,fec>.  
public static void sleep(int nSecond) uM`i!7}  
{ jlj ge=#c2  
try{ 66pjWS {X  
Thread.sleep(nSecond); Pj

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} (SRY(q  
catch(Exception e) ~6i'V?>  
{ g9" wX?*  
e.printStackTrace (); F9o7=5WAb  
} / rc[HbNg.  
} }dzdx"  
@.-S(MNR  
//日志 3UUdJh<~  
public static void log(String sMsg) \:J=tAC  
{ c},pu[nL  
System.err.println(sMsg); 5FR#CQ  
} x9Z89Gwi  
XZKlE F?  
B%6cgm,  
public static void log(int sMsg) Kz42AC  
{ z='%NZY  
System.err.println(sMsg); 0beP7}$  
} b~vV++ou_  
} I%J>~=]n_  
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/* ?) y}HF  
**TestMethod.java a|z-EKV  
*/ v](Y n)#  
package NetFox; eI$V2  
<9,h!  
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public class TestMethod { y-3'qq'E  
$~6MR_Yq  
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public TestMethod() )=Z;H"_  
{ ///xx/weblogic60b2_win.exe s0' haU  
try{ 3
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7{}E{/  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 7_2D4CI  
SiteFileFetch fileFetch = new SiteFileFetch(bean); sg7h&<Xx  
fileFetch.start(); CnB[ImMs(A  
} h}@wPP{  
catch(Exception e){e.printStackTrace ();} YjDQ`f/  
gFp3=s0~  
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} a5#G48'X  
!-OZ/^l|O`  
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public static void main(String[] args) jM$bWtq2  
{ qt@/  
new TestMethod(); +4%~.,<_to  
} L-w3A:jk  
} !s-A`} s+  
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