http断点续传简单实现（java)

/* i$6rnS&C  
**SiteFileFetch.java >1Hv c7DP  
*/ ){'<67dK  
package NetFox; /d:hW4}<}.  
import java.io.*; Y_jc*S  
import java.net.*; D|m3.si  
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public class SiteFileFetch extends Thread {
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SiteInfoBean siteInfoBean = null; //文件信息Bean kV T |(Y  
long[] nStartPos; //开始位置 (Sgsy^|N  
long[] nEndPos; //结束位置 tD}-&"REP  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 6B7*|R>  
long nFileLength; //文件长度 `O0Qtq.  
boolean bFirst = true; //是否第一次取文件 c^pQitPv  
boolean bStop = false; //停止标志 6m(? (6+;K  
File tmpFile; //文件下载的临时信息 _,aFQ^]'9  
DataOutputStream output; //输出到文件的输出流
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 4u%AZ<-C}m  
public SiteFileFetch(SiteInfoBean bean) throws IOException +75"Q:I  
{ jXALL8[c  
siteInfoBean = bean; (GpP=lSSeY  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); [M%?[E}>  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ,]:<l  
if(tmpFile.exists ()) a:UkVK]MP  
{ r4K9W90  
bFirst = false; !9KDdU  
read_nPos(); W#NZnxOX"  
} FGyrDRDwC  
else p_&B+ <z  
{ !z4I-a  
nStartPos = new long[bean.getNSplitter()]; sZr \mQ~  
nEndPos = new long[bean.getNSplitter()]; }[UH1+`L  
} K\;4;6g  
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} 4^:dmeMZ`  
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public void run() r*$f^T!|  
{ %k['<BYG<  
//获得文件长度 E#8|h(  
//分割文件 Shy.:XI  
//实例FileSplitterFetch .$W}  
//启动FileSplitterFetch线程 @sZ7Ka  
//等待子线程返回 X@tA+  
try{ F {L#  
if(bFirst) 
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{ hFr+K1  
nFileLength = getFileSize(); u t4:L
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if(nFileLength == -1) tKLeq(  
{ MnF|'t  
System.err.println("File Length is not known!"); ILH[q>  
} 5EI"5&`*  
else if(nFileLength == -2) mk!8>XvM  
{ w42{)S"  
System.err.println("File is not access!"); SC4jKm2  
} sH2xkUp  
else XP%_|Q2X  
{ 7_qsVhh]$E  
for(int i=0;i<nStartPos.length;i++) .|07IH/Di{  
{ VWK/(>TP  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Ank_;jo  
} dz/fSA  
for(int i=0;i<nEndPos.length-1;i++) kv2o.q  
{ uuD2O )v  
nEndPos = nStartPos[i+1]; \I4Uj.'>\  
} 1D8S}=5&  
nEndPos[nEndPos.length-1] = nFileLength; CPcUB4a%#  
} W=293mME  
} ~'0n ]Fw  
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//启动子线程 ;'V[8`Z@  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; DO*6gzW  
for(int i=0;i<nStartPos.length;i++) 1pDU}rPJ.  
{ 7]5~ml3:  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), P{`fav  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), PyHL`PZZ  
nStartPos,nEndPos,i); V/"RCqY4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ;Wk3>\nT-  
fileSplitterFetch.start(); +,ar`:x&a  
} H\<0{#F  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), C\BKdx5;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); y
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", P(8 uL|^  
nEndPos = " + nFileLength); |P|2E~[r  
// fileSplitterFetch[nPos.length-1].start(); O_th/hl  
[qkW/qS  
{6qxg_{  
//等待子线程结束 i(.PkYkaq  
//int count = 0; 9 4lt?|3=  
//是否结束while循环  (yd(ZY  
boolean breakWhile = false; p=x&X~  
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while(!bStop) P~:^bU^F7  
{ T8&sPt,f  
write_nPos(); 7^! zT  
Utility.sleep(500); Xg_l4!T_l  
breakWhile = true; s/11TgJ  
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for(int i=0;i<nStartPos.length;i++) $qZ6i  
{ |HY{Q1%
  
if(!fileSplitterFetch.bDownOver) =1|p$@L`%  
{ 55<!H-zt  
breakWhile = false; )*uotV  
break; +/mCYI  
} <^KW7M}w*c  
} @RuMo"js  
if(breakWhile) G}NqVbZ9]  
break; ><S2o%u~  
5pY|RV6:  
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//count++; saQ ~v@  
//if(count>4) #X$s5H  
// siteStop(); -:45Q{u/  
}
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System.err.println("文件下载结束！"); L5KcI  
} KY%qzq,n  
catch(Exception e){e.printStackTrace ();} 9X33{  
} Tl-%;X<X  
7AGUi+!ICl  
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//获得文件长度 ".#h$  
public long getFileSize() ~Cynw(  
{ ttlMZLX{TJ  
int nFileLength = -1; Y@MxKKuj  
try{ 3?_%|;ga  
URL url = new URL(siteInfoBean.getSSiteURL()); 'BgR01w J  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;KmrBNF  
httpConnection.setRequestProperty("User-Agent","NetFox"); (0_zp`)  
|{ZdAr.;  
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int responseCode=httpConnection.getResponseCode(); ScVbo3{m*T  
if(responseCode>=400) j!k$SDA-  
{ r#w7qEtD  
processErrorCode(responseCode); Z]k@pR !  
return -2; //-2 represent access is error $1zWQJd[-  
} !SGRK01  
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xy&*s\=:  
String sHeader; wzoT!-_X  
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for(int i=1;;i++) L %ifl:K  
{ `}$bJCSF.n  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Jx`7W1%T  
//Utility.log(in.readLine()); +eLL)uk  
sHeader=httpConnection.getHeaderFieldKey(i); L 9cXgd  
if(sHeader!=null) mC0Dj O  
{ i=P}i8,^=  
if(sHeader.equals("Content-Length")) P&tw!B  
{ *a{WJbau]  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); tBl(E  
break; ^x^(Rk}|  
} l)jP!k  
} :1gpbfW  
else #a
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break; [4dX[  
} ?`kZ6$  
} W.D>$R2  
catch(IOException e){e.printStackTrace ();} t pxk8Ys  
catch(Exception e){e.printStackTrace ();} JdWav!PYm  
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Utility.log(nFileLength); 9p^gF2?k  
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return nFileLength; 
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} [[';Hi^  
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//保存下载信息（文件指针位置） }:J-o  
private void write_nPos() H}CmSo8&  
{ q68m*1?y  
try{ [!uVo>Q4  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ^1_[UG  
output.writeInt(nStartPos.length); AqaMi  
for(int i=0;i<nStartPos.length;i++) d(b~s2\i  
{ [io|qLr}\  
// output.writeLong(nPos); -m ;n}ECg  
output.writeLong(fileSplitterFetch.nStartPos); a=9QwEZ  
output.writeLong(fileSplitterFetch.nEndPos); oQo5y_o~  
} ]P>X
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output.close(); BD^1V( I/  
} H(M{hfa|  
catch(IOException e){e.printStackTrace ();} m"'`$/_  
catch(Exception e){e.printStackTrace ();}
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} qss)5a/x.  
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//读取保存的下载信息（文件指针位置） MtoOIkQ  
private void read_nPos() {5d 5Y%&  
{ =2} kiLKO  
try{ fl2XI=[v4  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ga S}>?qk  
int nCount = input.readInt(); )DlK
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nStartPos = new long[nCount]; fYh<S  
nEndPos = new long[nCount]; n:k4t  
for(int i=0;i<nStartPos.length;i++) +#<Z/  
{ M1*bT@6  
nStartPos = input.readLong(); ###>0(n  
nEndPos = input.readLong(); AR$SQ_4  
} )%n$_N n  
input.close(); k{UeY[,jb  
} b&LAk-}[  
catch(IOException e){e.printStackTrace ();} l5KO_"hy  
catch(Exception e){e.printStackTrace ();} 27$,D XD  
} L<Z,@q`  
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:rjfAe=s  
private void processErrorCode(int nErrorCode) apfr>L3  
{ iXvrZofE  
System.err.println("Error Code : " + nErrorCode); HTvUt*U1  
} _)~VKA]""  
n}(A4^=4KQ  
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//停止文件下载 1Ax;|.KQH  
public void siteStop() *0Fz." v  
{ dB0 UZirb  
bStop = true; %k )H7nj  
for(int i=0;i<nStartPos.length;i++) y%kZ##  
fileSplitterFetch.splitterStop(); u3pFH(
 
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} e6jA4X+a  
} |(PS bu  
//负责部分文件的抓取 ,_,*I/o>B  
**FileSplitterFetch.java ae]6F_Qtc*  
*/ d~{$,"!-f  
package NetFox; X|ZAC!J5>  
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import java.io.*; d2-oy5cEB  
import java.net.*; .V3e>8gw3  
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public class FileSplitterFetch extends Thread { P~iZae  
jiLJiYMg  
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String sURL; //File URL ;YW@ 3F-h  
long nStartPos; //File Snippet Start Position VYO1qj  
long nEndPos; //File Snippet End Position 7\R"RH-  
int nThreadID; //Thread's ID .q[}e);)  
boolean bDownOver = false; //Downing is over D>HbJCG4^  
boolean bStop = false; //Stop identical CgYX^h?Y9  
FileAccessI fileAccessI = null; //File Access interface |d*a~T0  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException .uxM&|0H  
{ a
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this.sURL = sURL; R<{Vgy  
this.nStartPos = nStart; ;z N1Qb  
this.nEndPos = nEnd; +{I" e,Nk  
nThreadID = id; %%>nM'4<  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 $AE5n>ZD$  
} x-%RRm<V  
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public void run() e"NP]_vh,  
{ #Nco|v  
while(nStartPos < nEndPos && !bStop) :2,NKdD  
{ \hBzP^*"n  
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try{ CS(2bj^6D  
URL url = new URL(sURL); p:W]  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); gt02Csdt  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;+6><O!G  
String sProperty = "bytes="+nStartPos+"-"; ctjQBWE  
httpConnection.setRequestProperty("RANGE",sProperty); &vn2u bauS  
Utility.log(sProperty); pi/0~ke4"  
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1;V_E2?V  
InputStream input = httpConnection.getInputStream(); ~!8j,Bqs+z  
//logResponseHead(httpConnection); QKlsBq  
f
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byte[] b = new byte[1024]; 0< vJ*z|_  
int nRead; q^Oj/ws  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) dIYf}7P  
{ 9!W$S[ABRB  
nStartPos += fileAccessI.write(b,0,nRead); +jF2{"  
//if(nThreadID == 1) q#8yU\J|,  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Ro"'f7(v.  
} PoPR34]^J  
LbRQjwc]W  
 HG?+b  
Utility.log("Thread " + nThreadID + " is over!"); i$PO#}  
bDownOver = true; #ye`vD  
//nPos = fileAccessI.write (b,0,nRead); ljOY;WV3  
} kROIVO1|`  
catch(Exception e){e.printStackTrace ();} mTxqcQc:7  
} N!3Tg564j  
} z8JW iRn  
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//打印回应的头信息 &0-oi Y  
public void logResponseHead(HttpURLConnection con) liH#=C8l*%  
{ 'Kbrz  
for(int i=1;;i++) wL="p) TO.  
{ /W BmR R  
String header=con.getHeaderFieldKey(i); QDJ "X  
if(header!=null)  QSY>8P  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); $/IFSB9  
Utility.log(header+" : "+con.getHeaderField(header)); +,LWyvc'  
else tO:JB&vO2  
break; vszm9Qf
  
} HdB>CVuh  
} KU9FHN  
}YFM40H  
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public void splitterStop() 5:f!EMb  
{ f'@ L|&w  
bStop = true;
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} C)EP;5k'!\  
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} TPk?MeVy%W  
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/* B\)Te9k'  
**FileAccess.java TaBya0-  
*//文件访问(定位，写) DR}I+<*%aD  
package NetFox; _Tor9Tj  
import java.io.*; 2*z~'i  
uMZ~[Sz  
n>j2$m1[  
public class FileAccessI implements Serializable{ :e;6oC*"q  
DlE,aYB  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 $">j~!'  
RandomAccessFile oSavedFile; nf 8V:y4  
long nPos; FrXP"U}Y  
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public FileAccessI() throws IOException [B)!  
{ 5 k3m"*  
this("",0); /u4RZ|&as  
} C`g "Mk8  
3rH}/`d4  
@GQfBV|3  
public FileAccessI(String sName,long nPos) throws IOException P{6$".kIY  
{ jL"V0M]c  
oSavedFile = new RandomAccessFile(sName,"rw"); '!7>*<  
this.nPos = nPos; Lxv4w  
oSavedFile.seek(nPos); U\?D;ABQ%  
} 49&i];:%7%  
+?o!"SJ  
uo]xC+^  
public synchronized int write(byte[] b,int nStart,int nLen) &
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{ rBTg"^jsw  
int n = -1; X_o#!  
try{ iv *$!\Cd  
oSavedFile.write(b,nStart,nLen); %0C [v7\  
n = nLen; .F 6US<]  
} },l i'r#p  
catch(IOException e) \~E?;q!  
{ D0FX"B
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e.printStackTrace (); 3P2{M}WIl  
} P|$n   
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return n; ;kk[x8
$  
} Intuda7e1  
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} 5+M,X kg  
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/* }h45j84)  
**SiteInfoBean.java :C} I6v=  
*/ lK=Is v+  
package NetFox; u_^mN9h  
IRm}?hHf  
,Zn6T"[$  
public class SiteInfoBean { H%vfRl3rB  
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private String sSiteURL; //Site's URL
;um)JCXz  
private String sFilePath; //Saved File's Path l&+O*=#Hh  
private String sFileName; //Saved File's Name BJux5Nh  
private int nSplitter; //Count of Splited Downloading File r{R<J?Y  
);d07\V  
j9>[^t3U  
public SiteInfoBean() w{*kbGB8s7  
{//nSplitter的缺省值为5 KSchgon0V  
//default value of nSplitter is 5 <!Cjq,Sk7  
this("","","",5); h$'6."I  
} 6U*CR=4  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) O3o^%0  
{ Xs052c|s  
sSiteURL= sURL; metn&  
sFilePath = sPath; mxgT}L0i  
sFileName = sName; t8-Nli*O  
this.nSplitter = nSpiltter; uAA2G\3  
b_~XTWP$l  
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} x*vD^1"'P  
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public String getSSiteURL() Z8$BgP  
{ (uvQ/!  
return sSiteURL; }( F:U#  
} z;1dMQ,#  
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hE {";/}J  
public void setSSiteURL(String value) QGuqV8 y0  
{ S=r0tao,!v  
sSiteURL = value; TxPFl7,r  
} 9-T<gYl  
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e n~m)r3&  
public String getSFilePath() Sxq@W8W  
{ ck{S  
return sFilePath; T5u71C_wmt  
} 1- s(v)cxh  
66pjWS {X  
Pj

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public void setSFilePath(String value) (SRY(q  
{ >;MJm  
sFilePath = value; Q<V(#)*  
} 61H_o7XXk  
Xb%Q%"?~  
AaYH(2m-  
public String getSFileName() !ddyJJ^a  
{ Q[#}Oh6$  
return sFileName; N4ZV+ |  
} ({j8|{)+  
rgVRF44X{  
dHIk3j-!  
public void setSFileName(String value) Q)0KYKD+@  
{ Qz[^J  
sFileName = value; /Ot3[B  
} $,~Ily7w  
;-VZVp}Y  
r"2lcNE  
public int getNSplitter() .m]}Ba}J$  
{ pZ>yBY?R8>  
return nSplitter; [o<hQ`&  
} v>wN O  
%!nI]|  
!vf:mMo  
public void setNSplitter(int nCount) 8+[Vo_]  
{ &qS%~h%2  
nSplitter = nCount; BjfVNF;hk:  
} I/njyV)H  
} u"q
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/* X~jdOaq{F:  
**Utility.java
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*/ ,)[9RgsE  
package NetFox; b$DiDm  
U/enq,-F^  
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public class Utility { ikc1,o  
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? #rXc%F  
public Utility() oY^I|FEOz  
{ G~5pMyOR  
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} q2E{o)9  
3cghg._  
//线程睡眠 "6'",  
public static void sleep(int nSecond) f8lyH'z0 @  
{ $Lj]NtO  
try{ <u\Hy0g  
Thread.sleep(nSecond); b5|*p(7[  
} M3-lL;!n  
catch(Exception e) ,A{Bx`o?  
{ DKt98;  
e.printStackTrace (); 7=Muq]j2  
} our ^J8
  
} yDqwz[v b  
iKaX8c,zI  
//日志 /#Pm'i>B  
public static void log(String sMsg) u"qu!EY2  
{ "j_iq"J  
System.err.println(sMsg); "a[;{s{{.  
} vSnVq>-q&  
3`reXms*{  
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public static void log(int sMsg) v<v;ZR)  
{ }3: mn  
System.err.println(sMsg); W$`v^1M2o  
} *:H,
-@
 
} jz<}9Kze  
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/* o)5zvnu7  
**TestMethod.java twr{jdY9  
*/ v
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package NetFox; n0l|7:Mk  
?sQg{1"Zr  
)r46I$]>  
public class TestMethod { gg#9I(pX  
Ll=G+cw6P  
6HCg<_j]  
public TestMethod() q#3T L<  
{ ///xx/weblogic60b2_win.exe %J1'>nI!q  
try{ # QwX|x{  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 6c]4(%8  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); @;eH~3P  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 6 EqN>.  
fileFetch.start(); 3yRvs;nWS  
} F\N0<o  
catch(Exception e){e.printStackTrace ();} 7#C$}1XJ1  
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} 9!jF$  
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 d\#yWY  
public static void main(String[] args) AVjRhe  
{ f0g/`j@Up  
new TestMethod(); n@+?tYk*e  
} sX6\AYF1M  
} N-2#-poDe  
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