http断点续传简单实现（java)

/* XCm\z9F  
**SiteFileFetch.java 6b<+8w  
*/ C3)|<E  
package NetFox; /VO^5Dnb  
import java.io.*; wLUF v(&C  
import java.net.*; U{}!y3[wK  
tOM(U-7Z&  
>t0%?wj)Y  
public class SiteFileFetch extends Thread { @zrNN>  
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a.DX%C/5  
SiteInfoBean siteInfoBean = null; //文件信息Bean [sj VRW-  
long[] nStartPos; //开始位置 (
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long[] nEndPos; //结束位置 /l6\^Xf{  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 H_Os4}  
long nFileLength; //文件长度 Yx),6C3  
boolean bFirst = true; //是否第一次取文件 $/paEn"  
boolean bStop = false; //停止标志 _88QgThb  
File tmpFile; //文件下载的临时信息 Y\p$SN  
DataOutputStream output; //输出到文件的输出流 8R}K?+]  
@!<d0_dnC  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） bDWeU}  
public SiteFileFetch(SiteInfoBean bean) throws IOException f05=Mc&)  
{ x'qWM/  
siteInfoBean = bean; z]$>+MH_  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ?'wsIH]m  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); [4XC#OgA  
if(tmpFile.exists ()) @KA1"Wb_  
{ l E^*t`+  
bFirst = false; N_G4_12(  
read_nPos(); e:OyjG5_  
} 6/6Rah!  
else *b"CPg/\  
{ A,BEKjR~J  
nStartPos = new long[bean.getNSplitter()]; -72j:nk  
nEndPos = new long[bean.getNSplitter()]; h!e2 +4{4{  
} J &{xP8uq_  
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} *QH[,F`I  
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public void run() NR4Jn?l{  
{ 6^E`Sa!s  
//获得文件长度 o@/xPo|  
//分割文件 w<t,j~ Pr#  
//实例FileSplitterFetch >'`Sf ?+|  
//启动FileSplitterFetch线程 j[XYj6*d  
//等待子线程返回 n+;vjVS%  
try{ P+Z\3re  
if(bFirst) "- eZZEl(  
{ n3ZAF'  
nFileLength = getFileSize(); =Ndli>x}1  
if(nFileLength == -1) +O+<Go@a  
{ ooE{V*Ie  
System.err.println("File Length is not known!"); #s2B%X  
} y94kX:q  
else if(nFileLength == -2) %>y;zqZIU  
{ [se^.[0,  
System.err.println("File is not access!"); p<5!02yQ\  
} } 0M{A+  
else 8Kk\*8 <  
{ OCnFEX"  
for(int i=0;i<nStartPos.length;i++) [U.v:tR   
{ Rri`dmH   
nStartPos = (long)(i*(nFileLength/nStartPos.length)); GaBTj_3  
} VT=K"`EpQ  
for(int i=0;i<nEndPos.length-1;i++) JE!("]&  
{ =_PvrB2'  
nEndPos = nStartPos[i+1]; qC@Ar)T  
} -$YJfQE6G  
nEndPos[nEndPos.length-1] = nFileLength; XmWlv{T+  
} hz\WZ^  
} l67KJ  
t1ze-Ht;  
T?npQA07=  
//启动子线程 jGD%r~lN  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; (}gcY  
for(int i=0;i<nStartPos.length;i++) o| D^`Z  
{ <I2z&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), <>=mCZ2  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), d?hz LX  
nStartPos,nEndPos,i); 4D"4zp7  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 6)[<)?A.[  
fileSplitterFetch.start(); (oaYF+T  
} 6sB$<#  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), aB"xqh)a}T  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Rj6|Y"gq9  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", uGCp#>+  
nEndPos = " + nFileLength); saW!
9HQj  
// fileSplitterFetch[nPos.length-1].start(); @-"R$HOT  
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//等待子线程结束 z%:&#1)  
//int count = 0; uLVBM]Qj  
//是否结束while循环 AyVrk
8G  
boolean breakWhile = false; !wh&>3~  
'fY9a(Xt.  
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while(!bStop)
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{ Gv
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write_nPos(); T PYDs+U  
Utility.sleep(500); M"wue*&  
breakWhile = true; Q~Ea8UT.#  
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8;n_TMb  
for(int i=0;i<nStartPos.length;i++) 6E^~n  
{ &88oB6$D^q  
if(!fileSplitterFetch.bDownOver) ?+`xe{k  
{ 3M<!?%v\A  
breakWhile = false; /fwgqFVk  
break; -t3i^&fj8  
} 97LpY_sU  
} P}r)wAt  
if(breakWhile) h6M;0_'  
break; \Tm}mAvK/o  
36$[  
o""~jc~  
//count++; "2hh-L7ql  
//if(count>4) u\g,.C0  
// siteStop(); LE;g 0s  
} 6 hiC?2b{x  
+>YfRqz:KB  
vVVPw?Ww-  
System.err.println("文件下载结束！"); urZ8j?}c  
} )2.)3w1_4  
catch(Exception e){e.printStackTrace ();} '^}+Fv<O  
} ~UPZ<  
g.C5r]=+&  
+m/,,+4  
//获得文件长度 Jqfm@Y  
public long getFileSize() <Ar$v'W=F{  
{ +)/Uu3"=  
int nFileLength = -1; {#hVD4$b  
try{ 1"]P`SY$r  
URL url = new URL(siteInfoBean.getSSiteURL()); wahZK~,EaY  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); YQVcECj  
httpConnection.setRequestProperty("User-Agent","NetFox"); K=\&+at1  
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8^ #mvHah  
int responseCode=httpConnection.getResponseCode(); j_Nm87i]  
if(responseCode>=400) n1J]p#nCa.  
{ `X8@/wf#  
processErrorCode(responseCode); fRHKQ(a#  
return -2; //-2 represent access is error tXq)nfGe{  
} !OE*z $\  
FPv"N'/  
l(:kfR~AC  
String sHeader; )=_ycf^MC  
Y&f\VNlT  
#`ejU&!6  
for(int i=1;;i++) :zp`6l  
{ JN[0L:  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); .v])S}K  
//Utility.log(in.readLine()); @Icq1zb] y  
sHeader=httpConnection.getHeaderFieldKey(i); {fz$Z!8-  
if(sHeader!=null) k-jahm4  
{ oXgdLtsu  
if(sHeader.equals("Content-Length")) r"]'`qP,  
{ 0k[2jh  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); @d&H]5  
break; yrr) y  
} ?R'Y?b  
} JYmAn?o-  
else qX6D1X1_  
break; ,8VU&?`<}  
} VmvQvQ/9R  
} bToq$%sCg  
catch(IOException e){e.printStackTrace ();} wCb(>
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catch(Exception e){e.printStackTrace ();} f[jNwb  
658^"]Rk'/  
{eHAg<+  
Utility.log(nFileLength); H3O@9YU  
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return nFileLength; %SA!p;  
} 9- )qZ  
@*O?6>  
6"QEJ  
//保存下载信息（文件指针位置） j1U 5~%^  
private void write_nPos() PCE4W^ns  
{ OAe#Wf!c  
try{ LU2waq}VA  
output = new DataOutputStream(new FileOutputStream(tmpFile)); p3]Q^KFS  
output.writeInt(nStartPos.length); ;Icixu'O  
for(int i=0;i<nStartPos.length;i++) T|){<  
{ 6X_\Ve  
// output.writeLong(nPos); PHra+NY#A  
output.writeLong(fileSplitterFetch.nStartPos); j]5WK_~M  
output.writeLong(fileSplitterFetch.nEndPos); ZFxLBb:  
} EX "|H.(  
output.close(); Vfs$VY2.  
} PkUd~c  
catch(IOException e){e.printStackTrace ();} IVjU`ij  
catch(Exception e){e.printStackTrace ();} 7@;">`zvm  
} K4%/!`  
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Mr3-q  
//读取保存的下载信息（文件指针位置） Q*ju sm  
private void read_nPos() Sc$UZ/qPT  
{ ";NRzY  
try{ ]r/^9XaqtA  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); d7Ro}>lp  
int nCount = input.readInt(); wij,N(,H  
nStartPos = new long[nCount]; GjT#%GBF  
nEndPos = new long[nCount]; FN87^.^2S  
for(int i=0;i<nStartPos.length;i++) *@S@x{{s  
{ ^vni&sJ  
nStartPos = input.readLong(); }DjYGMrTB  
nEndPos = input.readLong(); 0^l%j8/  
} L^0v\  
input.close(); pGGmA;TC1  
} ?S[Y:<R{:  
catch(IOException e){e.printStackTrace ();} *3+-W  
catch(Exception e){e.printStackTrace ();} ,/2LY4` 5  
} 3S
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private void processErrorCode(int nErrorCode) z@U}~TvP  
{ IOl+t,0x&  
System.err.println("Error Code : " + nErrorCode); l
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} EbK0j?  
&t}?2>:  
c$H+g,7xQ-  
//停止文件下载 p]gT&[iJ  
public void siteStop() `!4,jd  
{ F4C!CUI  
bStop = true; +l0g`:  
for(int i=0;i<nStartPos.length;i++) 93Yn`Av;  
fileSplitterFetch.splitterStop(); M"Y0jQ(  
"lVqU  
]\c,BWC@e  
} \vbk#G hH  
} F:g=i}7  
//负责部分文件的抓取 ff2d@P,!  
**FileSplitterFetch.java _eQ-`?  
*/ HZjf
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package NetFox; 5J.0&Dda  
)e%}b-I'r  
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import java.io.*; MQTdk*L_]  
import java.net.*; oh-|'5+,;h  
cDkV;$  
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public class FileSplitterFetch extends Thread { -"TR\/  
:1wrVU-?h  
HEF?mD3h  
String sURL; //File URL -j2 (R?a  
long nStartPos; //File Snippet Start Position -K%5(Eg  
long nEndPos; //File Snippet End Position S-Fo  
int nThreadID; //Thread's ID 4YROB912
 
boolean bDownOver = false; //Downing is over <PD?f/4 /  
boolean bStop = false; //Stop identical {E_{JB~`  
FileAccessI fileAccessI = null; //File Access interface 2KJ1V+g@a6  
p~jlx~1-]  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 5f7zk  
{ ERMa# L  
this.sURL = sURL; 1Y/$,Oa5  
this.nStartPos = nStart; \Sy7"a  
this.nEndPos = nEnd; ot%.M*h-  
nThreadID = id; _^S]gmE  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 E1V^}dn  
} 7}o/:  
XEH}4;C'{  
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public void run() k5BXirB  
{ 3'I^lc  
while(nStartPos < nEndPos && !bStop) PGn);Baq  
{ lU4}B`#"v  
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try{ >t+ qe/  
URL url = new URL(sURL); ^>c8t_RG  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); @tT-JwU  
httpConnection.setRequestProperty("User-Agent","NetFox"); hsNWqk qys  
String sProperty = "bytes="+nStartPos+"-"; D{7w!z  
httpConnection.setRequestProperty("RANGE",sProperty); Qst$S}n  
Utility.log(sProperty); ^4Uw8-/9  
|`O5Xs1{B  
b~Y%gC)FR  
InputStream input = httpConnection.getInputStream(); tD=@SX'Y  
//logResponseHead(httpConnection); DocbxB={I  
z%d#@w0X1  
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byte[] b = new byte[1024];
J
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int nRead; B;#J"6w  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) @4+#Xd7"  
{ ~Qj}ijWD  
nStartPos += fileAccessI.write(b,0,nRead); Y}G_Z#-!  
//if(nThreadID == 1) ~f>2U]F>5  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); y0bq;(~X~  
} UXr5aZ7y  
S6i@"h5  
8F5|EpB9M  
Utility.log("Thread " + nThreadID + " is over!"); 'xK.UI  
bDownOver = true; Q(7ob}+jQ  
//nPos = fileAccessI.write (b,0,nRead); @E9" Zv-$  
} PO-"M)M  
catch(Exception e){e.printStackTrace ();} Tbbz'b;{  
} B|=|.qp$)  
} 0"WDH)7hJ  
7 h=QW5  
#(;<-7M2  
//打印回应的头信息 A$/\1282  
public void logResponseHead(HttpURLConnection con) :%rS =f  
{ rfcN/:k  
for(int i=1;;i++) }M>rE  
{ S7iDTG_@t  
String header=con.getHeaderFieldKey(i); /%rq hHs  
if(header!=null) eTay>G  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ,T{<vRj7_  
Utility.log(header+" : "+con.getHeaderField(header)); x34f9! 't  
else VRng=,  
break; O
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} W#w.h33)#6  
} Do7=#|bAM  
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public void splitterStop() T/r#H__`  
{ p]G3)s@>  
bStop = true; JgRYljQi2  
} k;yw#Af8  
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u eb-2[=  
} W m&  
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/* +JyUe    
**FileAccess.java k\r(=cex6  
*//文件访问(定位，写) <
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package NetFox; ;T+pu>)  
import java.io.*; j+4H}XyE  
*Ust[u  
_RkuBOv@e  
public class FileAccessI implements Serializable{ f2I6!_C!+  
{r85l\u)Q\  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 TX8<J>x  
RandomAccessFile oSavedFile; cQj-+Tmu  
long nPos; +/{L#e>  
hcCp,b  
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public FileAccessI() throws IOException Vy<HA*  
{ xG2F!WeF  
this("",0); o:q1beU  
} t~7V{ xk  

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public FileAccessI(String sName,long nPos) throws IOException w(d>HHg  
{ L5YnG_M&  
oSavedFile = new RandomAccessFile(sName,"rw"); Ucw yxXI  
this.nPos = nPos; _Xcn N:Rt  
oSavedFile.seek(nPos); `YBkF  
} Y4.Eq+$gh  
GwU?wIIj^  
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public synchronized int write(byte[] b,int nStart,int nLen) H].y w9  
{ $(pF;_W  
int n = -1; ; 0v>Rfa  
try{ | tQ
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oSavedFile.write(b,nStart,nLen); fnKY1y]2+  
n = nLen; =3~/:8o  
} u+t$l^S  
catch(IOException e) u"xJjS  
{ K0pac6]  
e.printStackTrace (); sM[I4.A3  
} {XurC}#\  
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^ZD
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return n; n.oUVr=nX  
} @F*wg  
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} B?rSjdY4  
=DbY?Q<Q  
;TiUpg</_3  
/* pv!oz2w1  
**SiteInfoBean.java [%A4]QzWh  
*/ `Pn[tuIO  
package NetFox; U:6W+p8  

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d&8APe  
public class SiteInfoBean { tMx}*l|]  
Q;Wj?8}  
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private String sSiteURL; //Site's URL pE.PX 8  
private String sFilePath; //Saved File's Path -5l6&Y   
private String sFileName; //Saved File's Name lfsqC};#\  
private int nSplitter; //Count of Splited Downloading File HL3XyP7  
/e}#' H   
.9[45][FK  
public SiteInfoBean() [k$*4u>  
{//nSplitter的缺省值为5 CI:^\-z  
//default value of nSplitter is 5 Z=5qX2fy1*  
this("","","",5); m(iR
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} Q:C$&-$  
:K82sCy%5  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) M]v=-  
{ U).*q?.z  
sSiteURL= sURL; $*a'84-5G-  
sFilePath = sPath; <N,)G |&  
sFileName = sName; DHC+C4  
this.nSplitter = nSpiltter; f
;SC{2f  
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} _M[,!
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public String getSSiteURL() Y<"7x#AB!  
{ cV{%^0?D  
return sSiteURL; 5v)(8|.M  
} }ov&.,vQ  
:1q4"tv|  
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public void setSSiteURL(String value) W,@ If}  
{ |tzg:T;  
sSiteURL = value; -tsDMji~V  
} ;!< Znw  
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6pOx'u>h+  
public String getSFilePath() nnb8Gcr  
{ >gKh  
return sFilePath; Syp"L;H8Em  
} 7r+g8+4  
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hd V1nS$  
public void setSFilePath(String value) P|2E2=G  
{ %Pqk63QF  
sFilePath = value; j;_c+w!P  
} Q zZ;Ob]'  
:4S%'d7  
pCpb;<JG  
public String getSFileName() 4F>Urh+  
{ IPSF]"}~  
return sFileName; mV73 \P6K  
} Cp`j/rF  
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public void setSFileName(String value) X2mREt9  
{ -7uwOr  
sFileName = value; }0`nvA
f  
} wfvU0]wk}  
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R`";Z$~{  
public int getNSplitter() H`8``#-|@S  
{ qa(>wR"m
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return nSplitter; ,6!rR,0  
} %S` v!*2  
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public void setNSplitter(int nCount) q{2I_[p  
{ }ZSQ>8a  
nSplitter = nCount; ffXyc2o  
} }u+a<:pkK  
} 6<,dRn  
m]_FQWfet  
qQi.?<d2"s  
/* thO ~=
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**Utility.java Ko&hj XHx  
*/ Ed0IWPx  
package NetFox; N!Qg;(  
cWGDee(  
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public class Utility { Dlo xrdOY&  
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B{oU,3U>  
public Utility() +(O~]Q-Ez  
{ nhSb~QqEh  
)5JU:jNy  
=K&\E2kA4  
} 6qe*@o  
6+V\t+aug  
//线程睡眠 N$Y" c*  
public static void sleep(int nSecond) P+t#4J  
{ Zn,>]X  
try{ <XT
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Thread.sleep(nSecond);
%;
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} k *R<,  
catch(Exception e) $qF0ltUQ  
{ t:JI!DR  
e.printStackTrace (); {ng"=3+n  
} 4`Nt{  
} -IlJ
^Al4  
;T
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//日志 /sR%]q |L  
public static void log(String sMsg) j` E +qk  
{ =.|J!
x  
System.err.println(sMsg); OI} &m^IOo  
} d0hhMx6$  
Y $g$x<7  
p\C%%  
public static void log(int sMsg) Obw?_@X  
{ Z3;!l  
System.err.println(sMsg); ~9F,%  
} 4E8JT#&  
} Xd:7"/:r  
5#3W5z  
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/* Vh3Ijn  
**TestMethod.java &Gm$:T'~  
*/ +,:^5{9{  
package NetFox; y5= `ap  
Ae^X35  
p <eC<dtu  
public class TestMethod { @ZN^1?][  
3$vRW.c\q  
Md)zEj`\  
public TestMethod() !KKT[28v  
{ ///xx/weblogic60b2_win.exe k^$+n_  
try{ J
68j=`Y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); M >:]lpRK  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); d;Hn#2C  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 3QI?[R.  
fileFetch.start(); %xwIt~Y  
} )Fd HV;K  
catch(Exception e){e.printStackTrace ();} rQ4*k'lA:  
4fh^[\  
0s#vwK13  
} }MR1^  
7;.xc{  
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public static void main(String[] args) ?EMK8;  
{ bG&"9b_c  
new TestMethod(); }14{2=!Q  
} %I!:ITa  
} < `qRA]  
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