http断点续传简单实现（java)

/* lLS7K8;4W  
**SiteFileFetch.java wotw nE  
*/ (P-$tHt  
package NetFox; v4,Dt  
import java.io.*; Hm
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import java.net.*; H`rd bE  
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public class SiteFileFetch extends Thread { m"wP]OQH*+  
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SiteInfoBean siteInfoBean = null; //文件信息Bean xcH&B%;f  
long[] nStartPos; //开始位置 I5ZM U  
long[] nEndPos; //结束位置 }d
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 t$rla_rbY  
long nFileLength; //文件长度 DTHWL  
boolean bFirst = true; //是否第一次取文件 ]AX3ov6z9;  
boolean bStop = false; //停止标志 |^"0bu"  
File tmpFile; //文件下载的临时信息 |mcc?*%t8  
DataOutputStream output; //输出到文件的输出流 zpZfsn!  
y2=yh30L0E  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） aP#/%  
public SiteFileFetch(SiteInfoBean bean) throws IOException #\\|:`YV  
{ z, n[}Q#u  
siteInfoBean = bean; gj I>tz}  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); my#\(E+  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); PlCj<b1D:  
if(tmpFile.exists ()) ],Yy)<e.  
{ |q
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bFirst = false; >T-4!ZvS\j  
read_nPos(); _PSOT5{  
} 5]n\E?V'L  
else |#'n VN.;  
{ ~0@fK<C)O  
nStartPos = new long[bean.getNSplitter()]; O&,8X-Ix  
nEndPos = new long[bean.getNSplitter()]; <T&v\DN  
} Fm*npK
 
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} (>NZYPw^3  
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public void run() nv\K!wZI=b  
{ \`E^>6!]q  
//获得文件长度 A0:rn\$l3  
//分割文件 B9Hib1<8  
//实例FileSplitterFetch N1B$z3E*  
//启动FileSplitterFetch线程 9zY6hh**  
//等待子线程返回 X-#&]^d  
try{ w 5?D]u  
if(bFirst) #'0Yzh]qc  
{ 2_y]MXG+%  
nFileLength = getFileSize(); ambr}+}  
if(nFileLength == -1) is~2{
:  
{ ,~DV0#"  
System.err.println("File Length is not known!"); .ws86stFSb  
} &BRa5`  
else if(nFileLength == -2) 6|~^P!&  
{ Id&e'  
System.err.println("File is not access!"); cqSXX++CS,  
} kguZAO6  
else :mW< E  
{
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for(int i=0;i<nStartPos.length;i++) P%gA`j  
{ /R&h#;l  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); WTJ{M$  
} o+7)cI  
for(int i=0;i<nEndPos.length-1;i++) x~vNUyEN)  
{ Fx|`0LI+C  
nEndPos = nStartPos[i+1]; _DH^ K9,9  
} ');vc~C  
nEndPos[nEndPos.length-1] = nFileLength; h<TZJCt  
} &lLfVa-l  
} 8-B7_GoJ+B  
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v"W*@7<`S  
//启动子线程 p6
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; `Z8k#z'bN  
for(int i=0;i<nStartPos.length;i++) %^L{K[}  
{ owQ,op#  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), b5LToy:  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), sQac%.H;`U  
nStartPos,nEndPos,i); YrB-n  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); *LU/3H|}  
fileSplitterFetch.start(); eqsmv[  
} PXkpttIE]M  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), RYjK4xT?Y/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); tP7<WGHd/  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", OtmDZ.t;`  
nEndPos = " + nFileLength); XFvl  
// fileSplitterFetch[nPos.length-1].start();
[I3Nu8  
HFZ'xp|3dn  
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//等待子线程结束 $_E.D>5^%7  
//int count = 0; 4,z|hY_*t  
//是否结束while循环 +tT"  
boolean breakWhile = false; b4i=%]v8  
9<.O=-1~  
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while(!bStop) C2"^YRN,  
{ }7[]d7  
write_nPos(); 8O9^g4?  
Utility.sleep(500); hm! J@  
breakWhile = true; U?le|tK  
iX]OF.:   
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for(int i=0;i<nStartPos.length;i++)  pE)NSZ  
{ L)J1yw  
if(!fileSplitterFetch.bDownOver) 2c 0;P #ol  
{ B[GC@]HE  
breakWhile = false; -je} PwT  
break; z7bJV/f  
} tfGs|x  
} "Zgwe,#  
if(breakWhile) x2"1,1%H7  
break; *v+l,z4n  
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//count++; /=m AVA  
//if(count>4) |VWT4*K  
// siteStop(); [g/D<g5O  
} ='o3<}  
i
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System.err.println("文件下载结束！"); "kyCY9)
%  
} :S0!  
catch(Exception e){e.printStackTrace ();} q>2bkcGY#  
} g%f5hy  
noxJr/A]  
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//获得文件长度 %;k Hnl  
public long getFileSize() lLTqk\8g  
{ 2F:qaz  
int nFileLength = -1; +twoUn{#  
try{ Ds">eNq  
URL url = new URL(siteInfoBean.getSSiteURL()); (4+P7Z,Nc  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); n^4R]9U  
httpConnection.setRequestProperty("User-Agent","NetFox"); lI=<lmM0|/  
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int responseCode=httpConnection.getResponseCode(); ?uq`|1`  
if(responseCode>=400) |:1{B1sqA  
{ xak)YOLRV  
processErrorCode(responseCode); ^<CVQ8R7  
return -2; //-2 represent access is error 'ZuS  
} bqcCA91  
!{lH*  
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String sHeader; @L3XBV2  
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for(int i=1;;i++) e2O6q05 ?Q  
{ l^lb ^"o  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); j,k3]
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//Utility.log(in.readLine()); 32YbBGDN!f  
sHeader=httpConnection.getHeaderFieldKey(i); g_Z tDxz  
if(sHeader!=null) h@Q^&%w  
{ ~#pATPW@
(  
if(sHeader.equals("Content-Length")) }D#:NlMp  
{ $H)^o!  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); {~U3|_"[pX  
break; F` U~(>u'  
} %2}fW\%'  
} u:l-qD9=(  
else yix[zfQt0  
break; QKG3>lU  
} %k!CjW3  
} npdljLN  
catch(IOException e){e.printStackTrace ();} xa~]t<2  
catch(Exception e){e.printStackTrace ();} I^
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Utility.log(nFileLength); |b  
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return nFileLength; :7v'[b  
} QUrPV[JQ  
1MN!  

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//保存下载信息（文件指针位置） -YA,Stc-  
private void write_nPos() aB,-E>+  
{ Rf:.'/<
^  
try{ HlGSt$woX  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 3!CUJs/W  
output.writeInt(nStartPos.length);
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for(int i=0;i<nStartPos.length;i++) <tr]bCu}  
{ 7~7L5PRW  
// output.writeLong(nPos); Su#0F0  
output.writeLong(fileSplitterFetch.nStartPos);
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output.writeLong(fileSplitterFetch.nEndPos); >i/jqT/  
} UL+Txc  
output.close(); |+#Zuq  
} p* >z:=  
catch(IOException e){e.printStackTrace ();} Tgdy;?  
catch(Exception e){e.printStackTrace ();} owAO&"C  
} y4^u&0}0$  
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//读取保存的下载信息（文件指针位置） 5UEZpxnv  
private void read_nPos() At Wv9  
{ t-\+t<;
 
try{ *6Wiq5M>.  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 1h,iWHC  
int nCount = input.readInt(); M(-)\~9T  
nStartPos = new long[nCount]; f"MID6  
nEndPos = new long[nCount]; fLDrit4_Q  
for(int i=0;i<nStartPos.length;i++) }icCp)b>v  
{ -,J<X\  
nStartPos = input.readLong(); KWJVc `  
nEndPos = input.readLong(); SDnl^a  
} +-izC%G  
input.close(); q}{E![ZTu  
} >*-%:ub  
catch(IOException e){e.printStackTrace ();} ? x)^f+:9|  
catch(Exception e){e.printStackTrace ();} )x.%P
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} ;blL\|ch;  
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":
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private void processErrorCode(int nErrorCode) ]Ry9{:  
{ "Y&I#&$b\  
System.err.println("Error Code : " + nErrorCode); s(,S~  
} sy&[Q{,4  
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"zEl2Xn28_  
//停止文件下载 $WAwMS,  
public void siteStop() RY-iFydPc  
{ G~9m,l+  
bStop = true; -cgO]q+Oq  
for(int i=0;i<nStartPos.length;i++) &^=Lr:I  
fileSplitterFetch.splitterStop(); ]
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#6 M]tr  
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} BQu |qrq  
} T.bFB+'E|  
//负责部分文件的抓取 {R1]tGOf  
**FileSplitterFetch.java ~D52b1f  
*/ ]H1mj#EWU  
package NetFox; OSu&vFKz  
-gn0@hS0  

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import java.io.*; {oQs*`=l>  
import java.net.*; Jh"[ug  
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public class FileSplitterFetch extends Thread { Jqoo&T")  
JE.$]){  
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String sURL; //File URL 6 @f>  
long nStartPos; //File Snippet Start Position EP>u%]#  
long nEndPos; //File Snippet End Position fNNl1Vls  
int nThreadID; //Thread's ID j\}.GM'8  
boolean bDownOver = false; //Downing is over VU3RFl  
boolean bStop = false; //Stop identical $|$@?H>K  
FileAccessI fileAccessI = null; //File Access interface Xaz "!  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException $QJ3~mG2  
{ bT:u|/I  
this.sURL = sURL; TmgC {_  
this.nStartPos = nStart; e!u]l  
this.nEndPos = nEnd; ?2@^O=I  
nThreadID = id; \/Y(m4<P
 
fileAccessI = new FileAccessI(sName,nStartPos);//定位 %\'=Y/yP  
} vC]X>P5Px  
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public void run() d) -(C1f  
{ VDxm|7  
while(nStartPos < nEndPos && !bStop) !j!w$  
{ 9<mMU:  
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try{ v
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URL url = new URL(sURL); b(K"CL\p  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); .@H:P  
httpConnection.setRequestProperty("User-Agent","NetFox"); \h ~_<)  
String sProperty = "bytes="+nStartPos+"-"; /-M:6  
httpConnection.setRequestProperty("RANGE",sProperty); OVL
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Utility.log(sProperty); /&gg].&2?  
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InputStream input = httpConnection.getInputStream(); * + T(i  
//logResponseHead(httpConnection); VEps|d3,,  
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byte[] b = new byte[1024]; Ip8ml0oG  
int nRead; p?gm=b#  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) q1ysT.{p,  
{ !5,C"r  
nStartPos += fileAccessI.write(b,0,nRead); J2O,wb)U  
//if(nThreadID == 1) &2ED<%hH`  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Us`=^\  
} 0)&!$@HW  
p]aEC+q  
%lCZ7z2o  
Utility.log("Thread " + nThreadID + " is over!"); s^u Y  
bDownOver = true; ::Zo` vP  
//nPos = fileAccessI.write (b,0,nRead); D07M!U  
} 3Gs\Q{O:  
catch(Exception e){e.printStackTrace ();} R3B+vLGX  
} SVU>q:ab  
} %`]+sg[i  
xs= ~N  
"0eX/rY%  
//打印回应的头信息 '5h`="  
public void logResponseHead(HttpURLConnection con) Q}#Je.;  
{ ZvRa"j  
for(int i=1;;i++) 0F[f%2j  
{ O3sV)  
String header=con.getHeaderFieldKey(i);
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if(header!=null) kjYM&q  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); NQ{(G8x9  
Utility.log(header+" : "+con.getHeaderField(header)); MblRdj6  
else ?V6,>e_+  
break; K P]ar.  
} um,f!ho-U  
} <-I69`  
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public void splitterStop() K<P d.:  
{ HzTmNm)  
bStop = true; ACyK#5E  
} K6DN>0sY  
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} `'1g>Ebk0  
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/* Znb={hh  
**FileAccess.java A.>mk598  
*//文件访问(定位，写) kY)Vr3uGA  
package NetFox; J*;RL`  
import java.io.*; Y-ao yoNS  
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public class FileAccessI implements Serializable{ GRcPzneiz  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 V,-we|"  
RandomAccessFile oSavedFile; |.k'?!  
long nPos; re*}a)iL  
s|\)
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public FileAccessI() throws IOException DhE-g<  
{ 9,?~
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this("",0); ,iV%{*p]  
} nXT`7  
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public FileAccessI(String sName,long nPos) throws IOException ep6+YK:cn  
{ z$Jm1l  
oSavedFile = new RandomAccessFile(sName,"rw"); G'JHimP2j  
this.nPos = nPos; DP{nvsF  
oSavedFile.seek(nPos); |^Io
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} NzT &K7v  
sT?{  
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public synchronized int write(byte[] b,int nStart,int nLen) h4]^~stI  
{ A4"TJZBg}  
int n = -1; q;68tEupR  
try{ AlQhKL}|s  
oSavedFile.write(b,nStart,nLen); &l+Qn'N  
n = nLen; l|.}>SfL^u  
} c,@Vz 7c  
catch(IOException e) CzBYH
 
{ y-hTTd"{  
e.printStackTrace (); h`6 (Oo|  
} &qbEF3p^@  
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return n; ~uhW~bT  
} ~:Rbd9IB  
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} Z:{| ?4  
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/* naR<  
**SiteInfoBean.java #aX#gh}1  
*/ KkUK" Vc  
package NetFox; Z=&|__+d  
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public class SiteInfoBean { oL]uY5eZoe  
MnD}i&k[  
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private String sSiteURL; //Site's URL :aOR@])>o  
private String sFilePath; //Saved File's Path $q\"d?n  
private String sFileName; //Saved File's Name d}O\:\}y  
private int nSplitter; //Count of Splited Downloading File S})f`X9_}  
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public SiteInfoBean() /Qst :q  
{//nSplitter的缺省值为5 k<1i.rh  
//default value of nSplitter is 5 o%'1=d3R1Q  
this("","","",5); K^!#;,0  
} G/JGb2I/7|  
^$'
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) rfonM~3?'  
{ <Z.`X7]Uk  
sSiteURL= sURL; F`4W5~`  
sFilePath = sPath; Pyuul4(  
sFileName = sName; s={>{,E  
this.nSplitter = nSpiltter; =bh: U90y  
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(EcP'F*;;y  
} _=0Ja S>M.  
f2c<-}wR  
x=H{Rv  
public String getSSiteURL() h 8$.mQr  
{ Do(G;D`h+_  
return sSiteURL; ~ox}e(xy  
} &/[MWQ  
WzFXF{(  
Hx6ODj[-  
public void setSSiteURL(String value) W^09tx/I  
{ E"*E[>  
sSiteURL = value; S$SCW<LuN  
} k(G6` dY  
X[
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1M`>;fjYa  
public String getSFilePath() u)h {"pP  
{ }eSy]r[J  
return sFilePath; egsP\ '  
} "yH?df2
4  
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public void setSFilePath(String value) wxBHlgK4z  
{ r3x;lICx-  
sFilePath = value; '?$@hq
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} FrMXf,}  
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Z5'^Hj1,  
public String getSFileName() ?J6Ek*E#  
{ LS*L XC  
return sFileName; RNB-W%  
} %H?B5y  
9.xb-m7  
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public void setSFileName(String value) W2h*t"5W  
{ d>#',C#;  
sFileName = value; 7}qxWz  
} jhz*Y}MX  
*# <%04f  
{QG6ld
I  
public int getNSplitter() mKTF@DED  
{ 7_36xpw  
return nSplitter; vy2<'V*y}  
} >lmqPuf  
fqbWD)L]  
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public void setNSplitter(int nCount) { #B/4  
{ r[):'ys,C  
nSplitter = nCount; A%EhRAy  
} ?v,c)  
} LV9R ]  
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/* Msvs98LvW  
**Utility.java U5ph4G  
*/ xxzUey  
package NetFox; wGMoh.GTh  
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public class Utility { dVq9'{[3  
3,Z;J5VL4!  
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public Utility() ('%Y3z;  
{ ekfa"X_  
9
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 0zr%8Q(Q  
} nT4Ryld  
V@RdvQy  
//线程睡眠 F@z%y'5 Z*  
public static void sleep(int nSecond) %d-WQwJ  
{ w&}<b%l  
try{ w?3ww7yf`  
Thread.sleep(nSecond); Q<szH1-  
} Y]~-S
 
catch(Exception e) IuFr:3(  
{ EBWM8~Nm#  
e.printStackTrace (); ]ZR` 6|"VO  
} |ggtb\W  
} _lT'nFe=Q  
7uUq+dp  
//日志 *E>R1bJ8  
public static void log(String sMsg) *\+oe+3  
{ 2>.b~q@  
System.err.println(sMsg); Uv?^qe0=  
} "7fEL:|j  
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F;/^5T3wI  
public static void log(int sMsg) qb=%W  
{ FP y}Wc*UA  
System.err.println(sMsg); s9Tn|Pm+!\  
} (-;(wCEE  
} ~[aV\r?  
toj5b;+4F  
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/* jpXbFWgN  
**TestMethod.java
-=lL{oB1  
*/ ]4')H;'y  
package NetFox; Bn.R,B0PL  
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public class TestMethod { <)_#6)z:  
wmMn1q0F  
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public TestMethod() Mj2Dat`p9  
{ ///xx/weblogic60b2_win.exe } nIYNeP?D  
try{ xIb{*)BUwc  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ]A\qI>,  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 5yJ~ q  
SiteFileFetch fileFetch = new SiteFileFetch(bean); cN2Pl%7  
fileFetch.start(); QYj 4D  
} ~U]%>Zf  
catch(Exception e){e.printStackTrace ();} c/F!cW{z^  
.'l3NV^{  
8t7r^[T  
} 9N2.:<so  
K0@bh/i/^  
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public static void main(String[] args) o5+7Lt]  
{ c>r~pY~$  
new TestMethod(); 7bVKH[  
} JHg;2xm"<K  
} |<1A<fU8
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