http断点续传简单实现（java)

/* |=js!R|  
**SiteFileFetch.java c!ieN9^+  
*/ +"1fr  
package NetFox; .
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import java.io.*; \q@Co42n\  
import java.net.*; gA}?X  
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*#9?9SYSk  
public class SiteFileFetch extends Thread { [Ob09#B%:5  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ;pj,U!{%s\  
long[] nStartPos; //开始位置 GTM@9^  
long[] nEndPos; //结束位置 0`V;;w8  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 xzHb+1+p  
long nFileLength; //文件长度 )FN\jo!!.  
boolean bFirst = true; //是否第一次取文件 z HT#bP:o  
boolean bStop = false; //停止标志 #/> a`Ur_  
File tmpFile; //文件下载的临时信息 Z!-V&H.
 
DataOutputStream output; //输出到文件的输出流 lK_T%1Gz  
:%_h'9Qq  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Vi`P &uPF  
public SiteFileFetch(SiteInfoBean bean) throws IOException &F:%y(;{Y  
{ WjguM  
siteInfoBean = bean; :T{VCw:*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 6of9lO:  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); S!rVq,| d  
if(tmpFile.exists ()) ,BFw-A  
{ sJ{r+wY  
bFirst = false; 8<Pi}RH  
read_nPos(); ~b@"ir+g4  
} Z((e-
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else *q"1I9zvT  
{ G.r .Z0  
nStartPos = new long[bean.getNSplitter()];
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nEndPos = new long[bean.getNSplitter()]; Dn)B19b  
} B@v (ZY  
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} =ld!=II  
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public void run() X.sOZb?$  
{ 7 0PGbAD  
//获得文件长度 m>|7&l_  
//分割文件 <0;G4fE7[H  
//实例FileSplitterFetch d3\KUR^  
//启动FileSplitterFetch线程 BiDyr  
//等待子线程返回 |ZC'a!  
try{ T% GR{mp  
if(bFirst) +koW3>  
{ >{l b|Vx  
nFileLength = getFileSize(); KrR`A(=WL  
if(nFileLength == -1) LP !d|X  
{ 3?D{iMRM  
System.err.println("File Length is not known!"); m&yHtnt  
} F"cZ$TL]  
else if(nFileLength == -2) "!_vQ^y  
{ gF`hlYD  
System.err.println("File is not access!"); Xvk+1:D  
} ~^'WHuzPy  
else ?gBFfi  
{ ~k%XW$cV  
for(int i=0;i<nStartPos.length;i++) /;vHAtt;f  
{ -BSO$'{7  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); b6xz\zCL  
} X,c`,B03  
for(int i=0;i<nEndPos.length-1;i++) "_2;+@+  
{ M)U)Sc zHO  
nEndPos = nStartPos[i+1]; *2fJdY  
} (&u'S+  
nEndPos[nEndPos.length-1] = nFileLength; rp^:{6O  
} gW^4@q  
} )?I*zc  
P,b&

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cltx(C>  
//启动子线程 qA[cF$CIl)  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; EG|_YW7  
for(int i=0;i<nStartPos.length;i++) Q+/P>5O/  
{ x0%yz+i{:  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), z`eMb  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), GXk |p8  
nStartPos,nEndPos,i); kkW}:dBl  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^x$1N
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fileSplitterFetch.start(); OI8}v  
} \%9QE  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Q,Y^9g"B`~  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); E^A!k=>  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", .|Yn[?(  
nEndPos = " + nFileLength); +~*e B  
// fileSplitterFetch[nPos.length-1].start(); I0><IaFy  
ef!f4u\  
H: ;XU  
//等待子线程结束 x8x-b>|$&<  
//int count = 0; 1|AY&u%fiP  
//是否结束while循环 fz?woVn  
boolean breakWhile = false; :`lP+y?a1  
\j-:5M#m  
Sx (E'?]  
while(!bStop) o?cNH  
{ vR>GE?s6  
write_nPos(); lauq(aD_C  
Utility.sleep(500); l_8ibLyo  
breakWhile = true; F@#p  
.XVL JJ#  
4#.Q|vyl]"  
for(int i=0;i<nStartPos.length;i++) mg>wv[ 7  
{ P!IXcPKW53  
if(!fileSplitterFetch.bDownOver) I[?bM-  
{ sl(go^  
breakWhile = false; uHRxV"@}[1  
break; "c?31$6  
} xn@oNKD0  
} ];5Auh0o  
if(breakWhile) (9=E5n6o  
break; /1D.Ud^  
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(i?9/8I  
//count++; 9Zmq7a E  
//if(count>4) |7Ab_  
// siteStop(); 9]lyV  
} A_e5Vb,u.  
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System.err.println("文件下载结束！"); &Nw|(z&$  
} _ b</ ::Tp  
catch(Exception e){e.printStackTrace ();} XX "3.zW  
} Sqyju3Yp  
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//获得文件长度 xP
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public long getFileSize() .<xD'54  
{ yq<W+b/  
int nFileLength = -1; P_H_\KsH*(  
try{ lDF7~N9J_  
URL url = new URL(siteInfoBean.getSSiteURL()); g:!R't?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); e\f\CMb  
httpConnection.setRequestProperty("User-Agent","NetFox"); &Vu-*?  
(d*||"  
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int responseCode=httpConnection.getResponseCode(); !4<A|$mQ  
if(responseCode>=400) ?AQA>D#W  
{ ts("(zI1E  
processErrorCode(responseCode); \PFjw9s  
return -2; //-2 represent access is error 2$VSH&  
} feeHXKD|  
1'iQlnMO@  
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String sHeader; W7@Vma`
 
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for(int i=1;;i++) `*`ZgTV  
{ #l.s>B4  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); @v!#_%J  
//Utility.log(in.readLine()); {x[C\vZsi]  
sHeader=httpConnection.getHeaderFieldKey(i); 4x?I,cAN  
if(sHeader!=null) o>T+fBHE  
{ y\[* mgl:  
if(sHeader.equals("Content-Length")) fF=tT C  
{ ]{#Xcqx  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ?YDMl  
break; =W2I0nr.  
} )q\6pO@  
} KoWG:~>|  
else Bn=YGEvz  
break; ?'"BX  
} )vg@Kc26  
} PlT_]p  
catch(IOException e){e.printStackTrace ();} \OWxf[  
catch(Exception e){e.printStackTrace ();} Lxv_{~I*  
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Utility.log(nFileLength); $fT#Wva-\d  
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return nFileLength; <]|!quY<*  
} yX%> %#$  
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_J#oAE5]!  
//保存下载信息（文件指针位置） Ir*{IV
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private void write_nPos() +qqCk  
{ "{3|(Qs  
try{ klY
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output = new DataOutputStream(new FileOutputStream(tmpFile)); twK3
  
output.writeInt(nStartPos.length); RyM29uD  
for(int i=0;i<nStartPos.length;i++) IjQgmS~G  
{ 8]O#L}"  
// output.writeLong(nPos); [a}Idi` K  
output.writeLong(fileSplitterFetch.nStartPos); F[0~{*/|G  
output.writeLong(fileSplitterFetch.nEndPos); x")Bmw$  
} e eyZ$n  
output.close(); TIaiJvo  
} n!lE|if  
catch(IOException e){e.printStackTrace ();} [9Tnp]q  
catch(Exception e){e.printStackTrace ();} 0AoWw-H6V  
} MBU4Awj  
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&_j<!3*  
//读取保存的下载信息（文件指针位置） *YX:e@Fm.a  
private void read_nPos() s$0dLEa9  
{ X &G]ci  
try{ BJLeE}=H  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); nr(C*E
 
int nCount = input.readInt(); -~H "zu`  
nStartPos = new long[nCount]; HzuG- V  
nEndPos = new long[nCount]; m`Z.xIA7;  
for(int i=0;i<nStartPos.length;i++) 9i{(GO  
{ :b_hF  
nStartPos = input.readLong(); pL>Yx>  
nEndPos = input.readLong(); z8)&ekG  
} qF`]}7"^  
input.close(); i~M-V=Zg  
} HW'I$ .  
catch(IOException e){e.printStackTrace ();} 'dv
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catch(Exception e){e.printStackTrace ();} 98uMD  
} w_LkS/  

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private void processErrorCode(int nErrorCode) "+ k}#<P4\  
{ fi&>;0?7  
System.err.println("Error Code : " + nErrorCode); i1]}Q$  
} 1-.i^Hal  
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/#L4ec-'  
//停止文件下载 %rEP.T\i
 
public void siteStop() 9VIAOky-  
{ T8W^qrx.v  
bStop = true; qDfhR`1k  
for(int i=0;i<nStartPos.length;i++) 8vfC  
fileSplitterFetch.splitterStop(); <$#^)]Ts  
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&XXr5ne~C  
} L&]{GNw  
} 
/7Q9(}  
//负责部分文件的抓取 _6YfPk+  
**FileSplitterFetch.java 1Vz3N/AP%?  
*/ {?A/1q4rr  
package NetFox; 8)83j6VF  
E(f|LG[I  
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import java.io.*; E5*pD*#  
import java.net.*; \Il?$Kb/  
c`\qupnY  
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public class FileSplitterFetch extends Thread { e<~bDFH  
OF;"%IW~}  
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String sURL; //File URL X
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long nStartPos; //File Snippet Start Position E%Ko[G  
long nEndPos; //File Snippet End Position r C
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int nThreadID; //Thread's ID }We-sZ/w7r  
boolean bDownOver = false; //Downing is over 3-[+g}kak?  
boolean bStop = false; //Stop identical r $YEq5  
FileAccessI fileAccessI = null; //File Access interface )2u_c=  
R[m+s=+  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException (S6>^:;=~  
{ ]IDhE{  
this.sURL = sURL; 5
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this.nStartPos = nStart; 5CH8;sMK  
this.nEndPos = nEnd;  _BCq9/  
nThreadID = id; y"K[#&,0  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 KR%NgV+}!0  
} 'mF&`BN}b  
*w6F0>u  
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public void run() };gcM@]]E  
{ Mi}k>5VT  
while(nStartPos < nEndPos && !bStop) 6!=q+sw/X  
{ Zl.,pcL  
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try{ Le,;)N
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URL url = new URL(sURL); gXY]NWI  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); C0ORBp  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'S9jMyZrZ  
String sProperty = "bytes="+nStartPos+"-"; 7dR]$~+*e  
httpConnection.setRequestProperty("RANGE",sProperty); ' wp _U/  
Utility.log(sProperty); \"Qa)1|  
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InputStream input = httpConnection.getInputStream(); S&Hgr_/}c  
//logResponseHead(httpConnection); YjPj#57+  
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3,Iu!KB  
byte[] b = new byte[1024]; Odw9]`,T  
int nRead; dkQP.Tj$i  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Pv*]AF;9pQ  
{ z1.vnGP  
nStartPos += fileAccessI.write(b,0,nRead); "DX2Mu=  
//if(nThreadID == 1) Dh<}j3]  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); :*t5?  
} <uo@k'   
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#TB 3|=  
Utility.log("Thread " + nThreadID + " is over!"); e=_Ng j)  
bDownOver = true; pTH5-l_f]  
//nPos = fileAccessI.write (b,0,nRead); jFI`CA6P  
} s;[WN.  
catch(Exception e){e.printStackTrace ();} {.Brh"yC  
} I:;umyRH  
} '<6DLtZl  
[88PCA:  
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//打印回应的头信息 $Xs`'>,"  
public void logResponseHead(HttpURLConnection con) YmHu8H_Q  
{ Bt(nm>Ng  
for(int i=1;;i++) Sb}=j;F  
{ p]7IoO -@  
String header=con.getHeaderFieldKey(i); |!CAxE0d$B  
if(header!=null) m<J:6^H@  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); *0_Q0SeE,o  
Utility.log(header+" : "+con.getHeaderField(header)); +.uQToqy  
else VWk{?*Dp  
break; ~CHVU3  
} *
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} nUCOHVI7  
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public void splitterStop() zT>BC}~.b  
{ k/)h@K8@  
bStop = true; N_l_^yD  
} E=]|v+#~  
ss`Sl$  
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} B'bOK`p  
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=}Yz[-I  
/* O<MO2U+^x  
**FileAccess.java p@oz[017/J  
*//文件访问(定位，写) Ue!yK  
package NetFox; StiWa<"c  
import java.io.*; [n3@*)q's  
D J7U6{KLq  
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public class FileAccessI implements Serializable{ mrig5{  
Mt@Ma ]!  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 WYIv&h<h"  
RandomAccessFile oSavedFile; N686~  
long nPos; 2AEVBkF;M  
{+EnJ"  
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public FileAccessI() throws IOException Zh`[A9I/  
{ b,>>E^wd!  
this("",0); 3u< ntx ><  
} 2q*wYuc  
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bGxHzzU}  
public FileAccessI(String sName,long nPos) throws IOException `v)ZOw9&  
{ lAkg47i  
oSavedFile = new RandomAccessFile(sName,"rw");
2WE01D9O  
this.nPos = nPos; 1*.*\4xo  
oSavedFile.seek(nPos); pnXwE-c_  
} sD|}?7  
p =-~qBw  
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public synchronized int write(byte[] b,int nStart,int nLen) ]<S{3F=  
{ )4>7X)j>  
int n = -1; ARG8\qU  
try{ t/l<X]o  
oSavedFile.write(b,nStart,nLen); P(
a}OlG  
n = nLen; %D~Mij  
} g8@F/$HY  
catch(IOException e) Lyit`j~yH  
{ $)d34JM  
e.printStackTrace (); Mh{>#Gs  
} Eqh*"hE7  
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return n; tq51;L  
} 45OAJ?N  
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} n
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/* EK&0Cn3z  
**SiteInfoBean.java )JJF}m=  
*/ ls~9qkAyLx  
package NetFox; #)3 B  
!OMCsUZ  
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public class SiteInfoBean { Xg;;< /Z  
mA@!t>=oMq  
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private String sSiteURL; //Site's URL cwzgIm+  
private String sFilePath; //Saved File's Path C>SOd]  
private String sFileName; //Saved File's Name ^'fgQyj  
private int nSplitter; //Count of Splited Downloading File y>)c?9X  
Y?L>KiM$
 
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public SiteInfoBean() (H\ `/%Bp  
{//nSplitter的缺省值为5 n
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//default value of nSplitter is 5 $VhY"<  
this("","","",5); &9"Y:),  
} f>|<5zm#
<  
_ {6l}  
KP7 {  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) wuW{2+)B  
{ D4uAwmc  
sSiteURL= sURL; V^rL  
sFilePath = sPath; [B+:)i  
sFileName = sName; c2?VjuB0  
this.nSplitter = nSpiltter; %?Q&a ]  
9ExI,  
6ud<U#\b&  
} >0uj\5h)I]  
`6;$Z)=.  
5:C>:pAV  
public String getSSiteURL() >s1?rC  
{ `5rfO6;  
return sSiteURL; [HL>Lp&A?  
} ZOpKi:\  
$?dQ^]<,  
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public void setSSiteURL(String value)  1'F!C  
{ EVC]B}  
sSiteURL = value; M
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} ! h92dH  
Od:-fw  
^P*-bV4  
public String getSFilePath() o\; hF3   
{ U<E]c 4*  
return sFilePath; d={o|Mf  
} `uZMln @  
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public void setSFilePath(String value) pjs4FZ`Pd;  
{ ?%Ww3cU+J  
sFilePath = value; e8#83|h  
} <q>d@Foi  
)[|_q,  
(E,Ibz2G:e  
public String getSFileName() 7upWM~H^  
{ yz5! >|EB  
return sFileName; 7[UD;&\k  
} q]VB}nO  
gNc;P[  
gS@<sO$d>  
public void setSFileName(String value) y.6/x?Qc  
{ .wyuB;:  
sFileName = value; $G5:/,Q  
} El: @l%  
&Yc'X+'4  
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public int getNSplitter() #TC}paIpj  
{ |\/\FK]?]  
return nSplitter; =8%*Rrj^  
} 1N:~5S}s>  
>EZZEd  
29VX-45  
public void setNSplitter(int nCount) xplV
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{ Wq"-T.i  
nSplitter = nCount; /oLY\>pD  
} MLg{Y?@  
} %u_dxpx  
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/* 72.Msnn  
**Utility.java x5V))~Ou  
*/ 6,MQT,F  
package NetFox; Yyr9Kj:  
-A=3W3:C  
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public class Utility { :Fu7T1  

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public Utility() BG= J8  
{ {@3v$W~7M  
E^br-{|{  
';My"/ Z-  
} L
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EtaKo}!A}  
//线程睡眠 ! K_<hNG&  
public static void sleep(int nSecond) E_DQ.!U!o  
{ ] $r].,&  
try{ yT5OFD|T  
Thread.sleep(nSecond); yU4mS;GX  
} nk7
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catch(Exception e) 9V[}#(f$  
{ sR[!6[AA  
e.printStackTrace (); )0ydSz`B  
} iyd$_CJz  
} N)AlQ'Lwx  

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//日志 1q3"qYH  
public static void log(String sMsg) D~URY_[A  
{ ey,f igjd.  
System.err.println(sMsg); 
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} VB#&`]rdo  
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Lo#G.
s|  
public static void log(int sMsg) x[Hx.G}5+  
{ peT9
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System.err.println(sMsg); i$Kx@,O8t  
} CCol>:8{P  
} /3K)$Er  
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l|E4 7@#  
/* >]ZE<.  
**TestMethod.java P}UxA!  
*/ N3aqNRwlk  
package NetFox; @ =~k[
o  
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UZrEFpi  
public class TestMethod { O(!;7v}  
h6^|f%\w*i  
sgGA0af  
public TestMethod() -,T!/E  
{ ///xx/weblogic60b2_win.exe V,0$mBYa  
try{ Wf"GA i  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); VHMQY*lk  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 0Xw>_#Y/xS  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 1[u{y{9 q  
fileFetch.start(); !<HMMf,-D  
} SQn.`0HT  
catch(Exception e){e.printStackTrace ();} VjNr<~|d  
Z"_8l3  
(a8iCci:   
} 2[uFAgf@  
1'Q6l  
Rvx7}ZL!  
public static void main(String[] args) !ehjLFS?_  
{ fCF.P"{W"  
new TestMethod(); $fT5Vc]B4  
} f\_PNZCc  
} qlYi:uygY  
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