http断点续传简单实现（java)

/*  px<psR5  
**SiteFileFetch.java b^VRpv  
*/ E{<#h9=>  
package NetFox; {^z73Gxt,  
import java.io.*; DjM*U52Yfj  
import java.net.*; AH#mL  
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public class SiteFileFetch extends Thread { Vr EGR$  
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SiteInfoBean siteInfoBean = null; //文件信息Bean QN#"c  
long[] nStartPos; //开始位置 6G2~'zqPc~  
long[] nEndPos; //结束位置 ,c&u\W=p  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 f~NS{gL*  
long nFileLength; //文件长度 &DWSf`:Hx  
boolean bFirst = true; //是否第一次取文件 M0w Uis:`
 
boolean bStop = false; //停止标志 EB}B75)x  
File tmpFile; //文件下载的临时信息 ij$NTY=u  
DataOutputStream output; //输出到文件的输出流 H~Uf2A)C  
1 pVw,}  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 4Y8=  
public SiteFileFetch(SiteInfoBean bean) throws IOException ,`bW(V  
{ F9 r5 Z  
siteInfoBean = bean; "z{/*uM2<  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); <[k3x8H'  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); C}h(WOcr`X  
if(tmpFile.exists ()) )/jDt dI  
{ TRi'l#m4  
bFirst = false; r
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read_nPos(); .V hU:_u  
} 6{I7)@>N  
else C~h#pAh  
{ y~+LzDV  
nStartPos = new long[bean.getNSplitter()]; B~I ]3
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nEndPos = new long[bean.getNSplitter()]; j\>&]0-Iq  
} Xex7Lr&  
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} }rJqMZ]w  
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public void run() >Lcu  
{ m~+.vk  
//获得文件长度 wrkw,H  
//分割文件 "o--MBq4  
//实例FileSplitterFetch &>c=/]Lop  
//启动FileSplitterFetch线程 .V!5Ui<  
//等待子线程返回 Vx!ZF+  
try{ xQZOGq  
if(bFirst) vE[d& b[  
{ MEI&]qI  
nFileLength = getFileSize(); [\ku,yd%0  
if(nFileLength == -1) ()|e xWW  
{ hWt_}'  
System.err.println("File Length is not known!"); tXzuP_0  
} c^_+<C-F  
else if(nFileLength == -2) iK4\N;H  
{ $D`Kz*/.  
System.err.println("File is not access!"); 3mo<O}}  
} gkK(7=r%  
else :tV"uWZFU  
{ bzG vnaTt  
for(int i=0;i<nStartPos.length;i++) 2_Lu0Yrg  
{ Lj /^cx  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); W(qK?"s2  
} n!zB+hW  
for(int i=0;i<nEndPos.length-1;i++) ):Fg {7b]n  
{ Wgf f+7k  
nEndPos = nStartPos[i+1]; 9vi+[3s/=;  
}
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nEndPos[nEndPos.length-1] = nFileLength; vmgd  
} s
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} JXuks`:Q  
p!E*ANwX  
AIP0PJI3  
//启动子线程 M7qg\1L  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; RQ8"vF#  
for(int i=0;i<nStartPos.length;i++) x6aVNH=  
{ :2 \NG}  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), G$)q% b;Lz  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), }Q[U4G  
nStartPos,nEndPos,i); 5#z7Hj&w  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); c CjN8<  
fileSplitterFetch.start(); =8vwaJ  
} O4nA?bA  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), fm#7}Y  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); D8k >f ]  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", uaD+G:{[  
nEndPos = " + nFileLength); aAcQmq TT  
// fileSplitterFetch[nPos.length-1].start();
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//等待子线程结束 >]B_+r0m^  
//int count = 0;  2X`t&zg  
//是否结束while循环 7yG%E  
boolean breakWhile = false; rXSw@pqZ&  
hB'rkjt  
k'v+/6 Y  
while(!bStop) mb'{@  
{ ^!m%:r7Dr  
write_nPos(); l(MjLXw5  
Utility.sleep(500); nF-l4=  
breakWhile = true; 9n5uO[D  
?5G;=#I  
4{,!'NA  
for(int i=0;i<nStartPos.length;i++) 2UR1T~r  
{ UN<$F yb  
if(!fileSplitterFetch.bDownOver) auB+g'l  
{ (wH+0  
breakWhile = false; C\[:{d  
break; #.FhN x  
} (Rs;+S  
} &/Gf@

[  
if(breakWhile) 9r:|u:i7m  
break; \1u^?cBd  
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//count++; HH3Z?g  
//if(count>4) f4`Nws-dP  
// siteStop(); [+@T"2h2b  
} P e} T  
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System.err.println("文件下载结束！"); CTqhXk[  
} &i805,lx  
catch(Exception e){e.printStackTrace ();} ?J|
 
} _Kli~$c& M  
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Y|#<kS  
//获得文件长度 Zirp_[KZ%  
public long getFileSize() cNKGEm ;z  
{ ocS}4.a@  
int nFileLength = -1; RdjoVCf  
try{ ,7d#t4  
URL url = new URL(siteInfoBean.getSSiteURL()); 7OPRf
9+o  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); xyV7MW\?w  
httpConnection.setRequestProperty("User-Agent","NetFox"); xNJ*TA[+  
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int responseCode=httpConnection.getResponseCode(); ~1Ffu x  
if(responseCode>=400) ZlMS=<hgFx  
{ 6m:$RW  
processErrorCode(responseCode); p`"Ic2xPJ  
return -2; //-2 represent access is error on7?V<  
} l>oJ^J  
: t D`e<  
;Rxc(tR!n  
String sHeader; aMK\&yZD  
z2A,*|I  
9+Wf*:
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for(int i=1;;i++) NwKj@Jos  
{ f(EO|d^u  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 1#zD7
b~  
//Utility.log(in.readLine()); i\>?b)a>  
sHeader=httpConnection.getHeaderFieldKey(i); ^= kr`5  
if(sHeader!=null) '~{kR=+  
{ V_4=
0(  
if(sHeader.equals("Content-Length")) MHCwjo"  
{ CQ{pv3)  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); /BS yanro  
break; M3fTUCR  
} ]<;y_  
} d|sf2   
else =+VDb5= TV  
break; msq2/sS~  
} ziQ&M\  
} Wq25,M'  
catch(IOException e){e.printStackTrace ();} wF-H{C'  
catch(Exception e){e.printStackTrace ();} kb\\F:w(W  
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KO))2GET  
Utility.log(nFileLength); e[QEOx/-h2  
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return nFileLength; w,1*dn  
} 94lz?-j  
~'Korxa  
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//保存下载信息（文件指针位置） r+a0.  
private void write_nPos() @><8YN^)%  
{ 7Xh ;dJAF3  
try{ +~xzgaL  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ,y)V5 c1  
output.writeInt(nStartPos.length); T|--ZRYn  
for(int i=0;i<nStartPos.length;i++) i@=(Y~tD`  
{ Xk:_aJ  
// output.writeLong(nPos); a!&<jM  
output.writeLong(fileSplitterFetch.nStartPos); 0|mCk  
output.writeLong(fileSplitterFetch.nEndPos); BtF7P}:MGf  
} `nd$6i^#W  
output.close(); ddlF4L_  
} j9f QV  
catch(IOException e){e.printStackTrace ();} "i%=QON`  
catch(Exception e){e.printStackTrace ();} HC$}KoZkC  
} A4)TJY 3g  
5_rx$avm  
/vLW{%  
//读取保存的下载信息（文件指针位置） DH])Q5  
private void read_nPos() .aC/ g?U  
{ 7Y 4!  
try{ G#.q%Up  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); (Wn^~-`=+  
int nCount = input.readInt(); Xz'o<S  
nStartPos = new long[nCount];  p-6T,')  
nEndPos = new long[nCount]; G[zVGqk  
for(int i=0;i<nStartPos.length;i++) G4EuW *~
 
{ e'3y^Vg  
nStartPos = input.readLong(); [n$6T  
nEndPos = input.readLong(); %\1W0%w  
} O~5*X f  
input.close(); ,UxAHCR~9  
} *3(mNpi{_  
catch(IOException e){e.printStackTrace ();} T?*f}J  
catch(Exception e){e.printStackTrace ();} 5~RR _G  
} xQxq33\  
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private void processErrorCode(int nErrorCode) dSE"G>l8  
{ g7v(g?  
System.err.println("Error Code : " + nErrorCode); (J.U{N v  
} Sj<]~*y"  
b%xG^jUXsX  
}u;`k'J@  
//停止文件下载 &Y2Dft_K  
public void siteStop() "BC;zH:  
{ :d|~k  
bStop = true; 3 5p)e c  
for(int i=0;i<nStartPos.length;i++) R-Gg= l5  
fileSplitterFetch.splitterStop(); YN7JJJ/~T  
}k@SmO8  

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} tPFj[Y~Iy  
} eI/5foA  
//负责部分文件的抓取 [I( Yn  
**FileSplitterFetch.java ;IR.6k$;  
*/ ,b t j6hg  
package NetFox; rb]?"lizi  
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import java.io.*; :CP,DO
 
import java.net.*; ka*#O"}L8  
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WIw*//nw  
public class FileSplitterFetch extends Thread { 5p~hUP]tT  
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String sURL; //File URL D/Py?<n-B  
long nStartPos; //File Snippet Start Position ZQ_AqzT3D  
long nEndPos; //File Snippet End Position *_K*GCy  
int nThreadID; //Thread's ID ULzrJbP'7  
boolean bDownOver = false; //Downing is over o`Q.;1(Y'  
boolean bStop = false; //Stop identical uP^u:'VjbH  
FileAccessI fileAccessI = null; //File Access interface KESM5p"f  
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H  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException M]SeNYDy  
{ f%rZ2h)  
this.sURL = sURL; wotw nE  
this.nStartPos = nStart; sAoxLI  
this.nEndPos = nEnd; YVPLHwh/5  
nThreadID = id; 6K^O.VoV^J  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 wQ81wfr1:  
} No*[@D]g  
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public void run() H4<Q}([w  
{ V+t's*9o3  
while(nStartPos < nEndPos && !bStop) l\ VrD2j8  
{ $t0JfDd6Ky  
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upGLZ#  
try{ _IWLC{%V  
URL url = new URL(sURL); xcH&B%;f  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #tA/)Jvi  
httpConnection.setRequestProperty("User-Agent","NetFox"); W"&,=wvg2  
String sProperty = "bytes="+nStartPos+"-"; }d
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httpConnection.setRequestProperty("RANGE",sProperty); 9^@)R ED  
Utility.log(sProperty); bbT$$b-  
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InputStream input = httpConnection.getInputStream(); R$;TX^r'o&  
//logResponseHead(httpConnection); `i<Z< <c>  
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byte[] b = new byte[1024]; eg24.W9c  
int nRead; N! I$Qtr,  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) R[OXYHu  
{ -_XTy!I  
nStartPos += fileAccessI.write(b,0,nRead); z7TyS.z  
//if(nThreadID == 1) 6w[EJ;=p_  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); wOsg,p;\'  
} I{=Yuc  
 45WJb+$  
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Utility.log("Thread " + nThreadID + " is over!"); U*?`tdXJ$  
bDownOver = true; Zn[ppsz|  
//nPos = fileAccessI.write (b,0,nRead); %< `D'V@  
} =nqHVRA  
catch(Exception e){e.printStackTrace ();} dg_w$#  
} 5]n\E?V'L  
} [v`kqL~  
:aH5=@[!y  
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//打印回应的头信息 Eihn%Esa  
public void logResponseHead(HttpURLConnection con) "F[7b!>R  
{ _<=h#lH  
for(int i=1;;i++) lnRL^ }  
{ -!}3bl*(7  
String header=con.getHeaderFieldKey(i); h}kJ,n  
if(header!=null) -gUp/#l1  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); %Aqf=R_^  
Utility.log(header+" : "+con.getHeaderField(header)); $lq.*UQ;0  
else SmIcqM  
break; aemi;61T\  
} opMnLor  
} /aIGq/;Y+a  
]sJC%/  
'gHg&E9E&  
public void splitterStop() Xj~%kPe  
{ ~S\> F\v6'  
bStop = true; ;#:AM;  
} -&=dl_m  
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} n>w<vM  
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/* n2EPx(~  
**FileAccess.java Hq!|r8@6  
*//文件访问(定位，写) </u=<^ire  
package NetFox; *QV"o{V  
import java.io.*; ambr}+}  

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i  
public class FileAccessI implements Serializable{ 2;0eW&e   
0[e!/*_V  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 6?;z\AP&  
RandomAccessFile oSavedFile; 9g>)7Ne  
long nPos; 8g Z)c\  
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public FileAccessI() throws IOException c+ e~BN  
{ 8;r#HtFM  
this("",0); *0to,$ n  
} i;-M8Q^  
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public FileAccessI(String sName,long nPos) throws IOException aU^6FI  
{ b?c/J{me  
oSavedFile = new RandomAccessFile(sName,"rw"); U7?v4O]D[  
this.nPos = nPos; 0Qq<h;8xEc  
oSavedFile.seek(nPos); =*"8N-FU  
} ]Yw$A  
ts9wSx~[+  
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public synchronized int write(byte[] b,int nStart,int nLen) ^ nI2<P  
{ GEA1y^b6"  
int n = -1; g,rmGu3v  
try{ _DH^ K9,9  
oSavedFile.write(b,nStart,nLen); m\X\Xp~A  
n = nLen; J=k=cFUX  
} }ML2-k  
catch(IOException e) &lLfVa-l  
{ U||GeEd  
e.printStackTrace (); =$fz</S=J  
} ,
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return n; `Z8k#z'bN  
} <|jh3Hlp  
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} IEMa/[n/  
7HBf^N.  
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/* FK593z  
**SiteInfoBean.java ?-vWNv  
*/ dGn0-l'q  
package NetFox; eqsmv[  
j~G(7t  

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public class SiteInfoBean { RYjK4xT?Y/  
}b&lHr'Uw  
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private String sSiteURL; //Site's URL oV0T   
private String sFilePath; //Saved File's Path #Uu,yHMv:;  
private String sFileName; //Saved File's Name W>C?a=r~  
private int nSplitter; //Count of Splited Downloading File f|FS%]fCxk  
]LUcOR  
tVEe)QX  
public SiteInfoBean() {0Y6jk>I  
{//nSplitter的缺省值为5 $_E.D>5^%7  
//default value of nSplitter is 5 k#Sr;"  
this("","","",5); &hI!mo  
} IBo  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) rZJJ\ , |  
{ e,/]]E/o  
sSiteURL= sURL; ZK+F<}  
sFilePath = sPath; jDpA>{O[  
sFileName = sName; 94BH{9b5  
this.nSplitter = nSpiltter; ={sjoMW  
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5@m ,*n&[  
} ]690ey$E:j  
(.cA'f?h  
r|u[36NmA  
public String getSSiteURL() zR?R,k)m  
{ w;`Jj-  
return sSiteURL; $|-Lw!)D  
} m0TVi]v  
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public void setSSiteURL(String value) Y b3ckktY  
{ rs{)4.I  
sSiteURL = value; Sk cK>i.[  
} ;v@
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public String getSFilePath() 0BlEt1e2T  
{ f?Zjd&|Ch  
return sFilePath; <v|"eq}  
} ,bl }@0A  
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6I +0@,I  
public void setSFilePath(String value) ES&u*X:  
{ 7qB
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sFilePath = value; 1"ZtE\{ "  
}
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public String getSFileName() DJ,LQj  
{ i *.Y  
return sFileName; >,{sFc  
} Q^Cm3|ZO  
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public void setSFileName(String value) z}!g2
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{ pD%(Y^h?  
sFileName = value; O D}RnKL  
} ~~OFymQ%?q  
**hQb$  
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public int getNSplitter() g8##Be  
{ 51q|-d  
return nSplitter; u]IbTJ'
 
} kWXLncE  
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wc;n= %  
public void setNSplitter(int nCount) 2F:qaz  
{ }8ubGMr,Y  
nSplitter = nCount; 7EE{*}?0E  
} T?pS2I~  
} \sAaVdZJH(  
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/* U|} ?{x  
**Utility.java VV$t*9w  
*/ ,
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package NetFox; ?uq`|1`  
ApCU|*r)  
]$@a.#}  
public class Utility { kcCCa@~v  
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public Utility() W "'6M=*  
{ $y8-JR~  
1D*=ZkA)  
1|MRXK  
} ]y0Y(  
}<04\t?  
//线程睡眠 'I]XX==_  
public static void sleep(int nSecond) )!"fUz$  
{ +-!E%$
 
try{ S\A/*!%~y  
Thread.sleep(nSecond); X2|~(*  
} R@o&c%K"  
catch(Exception e)  'o-4'  
{ 7)lEZJK&T  
e.printStackTrace (); m-Eh0Zl>Z  
} dz_S6o ]  
} R*[sO*h\k  
=fcg4h5(  
//日志
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public static void log(String sMsg) p~$c
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{ O(T5  
System.err.println(sMsg); $H)^o!  
} 4@PA+(kvS  
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public static void log(int sMsg) :o'x?]  
{ 3Z b]@n  
System.err.println(sMsg); d
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} yix[zfQt0  
} jc5[r;#  
')"+ a^c  
CvoFt=c$jE  
/* npdljLN  
**TestMethod.java %_OjmXOfe  
*/ ^#Ii=K-[^  
package NetFox; <u64)8'  
N''QQBUD  
yKc-:IBb{u  
public class TestMethod { uR
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b[74$W{  
T`&zQQ6F'  
public TestMethod() rW{!8FhI  
{ ///xx/weblogic60b2_win.exe 0pZvW  
try{ ]@{Lx>Oh"  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); my?Ly(#  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); jxog8E  
SiteFileFetch fileFetch = new SiteFileFetch(bean); |toP86  
fileFetch.start(); yb`PMjj15  
} C96/   
catch(Exception e){e.printStackTrace ();} R_!.vGhkN  
$YSXE :  
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} QQ(}71U  
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3Ua?^2l  
public static void main(String[] args) EW `hL~{  
{ b#VtPn]  
new TestMethod(); 3!CUJs/W  
} I1
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} GcBqe=/B!  
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