http断点续传简单实现（java)

/* T!^v^m@>y  
**SiteFileFetch.java l701$>>  
*/ *,=8x\Shp  
package NetFox; 9j5-/   
import java.io.*; 3[ xHY@c  
import java.net.*; /R>YDout}  
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public class SiteFileFetch extends Thread { 8~|v:qk  
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SiteInfoBean siteInfoBean = null; //文件信息Bean <KI>:@|Sc  
long[] nStartPos; //开始位置 :EH>&vm  
long[] nEndPos; //结束位置 us.IdG  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 :X}Ie P  
long nFileLength; //文件长度 bwJluJ,E  
boolean bFirst = true; //是否第一次取文件 0+.<BOcW5  
boolean bStop = false; //停止标志 Xc~BHEp  
File tmpFile; //文件下载的临时信息 n_wF_K\h  
DataOutputStream output; //输出到文件的输出流 7c6- o"A  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ]c]^(C  
public SiteFileFetch(SiteInfoBean bean) throws IOException 3/]~#y%2  
{ _p^Wc.[~M  
siteInfoBean = bean; _!w69>Nj  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 9Q7342  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Zvr
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if(tmpFile.exists ()) u EERNo&  
{ bHXoZix  
bFirst = false; w U1[/  
read_nPos(); XK;Vu#E*^  
} r-Y7wM`TZ  
else +k/=L9#e  
{ wbg?IvY[  
nStartPos = new long[bean.getNSplitter()]; K1&t>2=%  
nEndPos = new long[bean.getNSplitter()]; _3#_6>=M  
} $)KNpdXh  
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} yf4 i!~  
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public void run() aEun *V^,  
{ ]Z52L`k  
//获得文件长度 }VHvC"  
//分割文件 ~&"'>C#  
//实例FileSplitterFetch H wz$zF+R  
//启动FileSplitterFetch线程 bkrl>Im<n  
//等待子线程返回 . +,{|){c  
try{ ZoCk]hk  
if(bFirst) +6^hp-G7  
{ 6 B7F  
nFileLength = getFileSize(); mXyg\5  
if(nFileLength == -1) q%,y66pFr  
{ ~ftR:F|9  
System.err.println("File Length is not known!"); ]3Jb$Q@  
} C^:{y  
else if(nFileLength == -2) ~4xn^.w  
{ ,|j\x  
System.err.println("File is not access!"); z.OJ1vY7  
} k`s_31<  
else 0n={Mb  
{ 90ov[|MkM  
for(int i=0;i<nStartPos.length;i++) kv2 H3O  
{ 2Zg%4/u,Zp  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); `(6cRT`Wp  
} h8;H<Y;yQ  
for(int i=0;i<nEndPos.length-1;i++) 7|o}m}yVx
 
{ %zhSSB=BJ  
nEndPos = nStartPos[i+1]; 3T[zieX  
} czB),vooz  
nEndPos[nEndPos.length-1] = nFileLength; b'vIX< g  
} _ D"S  
} :8N{;aui  
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//启动子线程 ZmJ<FF4  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; OM`Ws5W}f  
for(int i=0;i<nStartPos.length;i++) ~D`  
{ Dr"PS >.  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), =Wz)(N  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), A7T(p7pP  
nStartPos,nEndPos,i); uC[F'\Y  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 0C6T>E7  
fileSplitterFetch.start(); 7y$U$6  
} 3FMYs&0r4  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ^Cj3\G4,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 9V;A+d,  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", E 0@u|  
nEndPos = " + nFileLength); E5
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// fileSplitterFetch[nPos.length-1].start(); L[U?{  
AtqsrYj  
:4LWm<P  
//等待子线程结束 l7Wdbx5x0  
//int count = 0; M<SVH_  
//是否结束while循环 e+?;Dc-SJ\  
boolean breakWhile = false; ):n'B` f}z  
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while(!bStop) Lzx/9PPYn  
{ N9u {)u  
write_nPos(); 4E$d"D5]>p  
Utility.sleep(500); \{qtdTd  
breakWhile = true; +F>erdV  
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for(int i=0;i<nStartPos.length;i++) <L2z|%`  
{ =dp`4
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if(!fileSplitterFetch.bDownOver) R'oGsaPB2  
{ hdqr~9  
breakWhile = false; $8Z4jo  
break; S7@/dHN  
} R_vK^Da  
} oq,*@5xV2  
if(breakWhile) &gI*[5v  
break; vtc%MG1  
Ga pM~~  
/!60oV4p0  
//count++; Q@*9|6-  
//if(count>4) (^]3l%Ed  
// siteStop(); /PG%Y]l0b  
} ^KV:.up6  
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System.err.println("文件下载结束！"); $F]*B `  
} g'EPdE  
catch(Exception e){e.printStackTrace ();} di<g"8  
} +;bZ(_ohG  
:*cd$s  
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//获得文件长度 []?*}o5&>T  
public long getFileSize() /74)c~.W  
{ G\(*z4@Gz  
int nFileLength = -1; dki3(  
try{ V|<'o<h8  
URL url = new URL(siteInfoBean.getSSiteURL()); lQ4$d{m`  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Q,};O$h  
httpConnection.setRequestProperty("User-Agent","NetFox"); 4Vd[cRh2  
gyU=v{].  
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int responseCode=httpConnection.getResponseCode(); V8Z@y&ny  
if(responseCode>=400) ZbH_h]1$D  
{ j_b/66JyN  
processErrorCode(responseCode); Zj0h0Vt  
return -2; //-2 represent access is error 7>EMr}f C  
} rAD4}A_w  
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String sHeader; Ft_g~]kZo  
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for(int i=1;;i++) !|cM<}TF,  
{ :\%hv>}|  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); B|=S-5pv*  
//Utility.log(in.readLine()); Qh]k)]+*|  
sHeader=httpConnection.getHeaderFieldKey(i); ]|[mwC4  
if(sHeader!=null) 7(H?3)%0  
{ SE$l,Z"[*b  
if(sHeader.equals("Content-Length")) 6}*4co  
{ &0{&4,  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); BT f  
break; Hdjp^O!  
} V-"#Kf9  
} !.O;S
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else %PPkT]~\  
break; <irr.O  
} s,M]f,T  
} 8/~@3-9EK  
catch(IOException e){e.printStackTrace ();} eUD 5V  
catch(Exception e){e.printStackTrace ();} m`4N1egCt  
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Utility.log(nFileLength); J@rBrKC  
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return nFileLength; 2N.!#~_2D  
} "M,H
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//保存下载信息（文件指针位置） ~b[5}_L=>  
private void write_nPos() V]Uc@7S/  
{ >&T J  
try{ semTAoqH  
output = new DataOutputStream(new FileOutputStream(tmpFile)); q{!ft9|K\d  
output.writeInt(nStartPos.length); 6f+@@=Xc  
for(int i=0;i<nStartPos.length;i++) !)`m mr  
{ hl,x|.f}4Y  
// output.writeLong(nPos); )?(_vrc<  
output.writeLong(fileSplitterFetch.nStartPos); |w>d]eA5  
output.writeLong(fileSplitterFetch.nEndPos); '1Ex{

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} $`L |
 
output.close(); _gpf9ad  
} v}@Uc-(  
catch(IOException e){e.printStackTrace ();} "a<:fEsSE  
catch(Exception e){e.printStackTrace ();} C~M,N|m+^  
} qI[AsM+  
^vI`#}?  
w=~X6[+3  
//读取保存的下载信息（文件指针位置） t*-_MG  
private void read_nPos() 5K=>x<  
{ #zc$cr  
try{ r\q|DZ7  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); i1Y<[s  
int nCount = input.readInt();  o%$R`;  
nStartPos = new long[nCount]; }RQHsS  
nEndPos = new long[nCount]; SOS|3q_`  
for(int i=0;i<nStartPos.length;i++)  3X9  
{ G(1_P1  
nStartPos = input.readLong(); `b_n\pf]  
nEndPos = input.readLong(); /K<>OyR?  
} iS`ok  
input.close(); 6s$h _$[X  
} Y*S(uqM  
catch(IOException e){e.printStackTrace ();} :S+Bu*OyH
 
catch(Exception e){e.printStackTrace ();} ^[q/w<_j~  
} 1W7ClT_cQ  
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private void processErrorCode(int nErrorCode) \WZSY||C|_  
{ Zy>y7O(,  
System.err.println("Error Code : " + nErrorCode); M2A_T.F=H  
} 98CS|NEe  
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//停止文件下载 NHhKEx0Gtu  
public void siteStop() YIHGXi<"n  
{ F*y7 4j,  
bStop = true; :]8!G- Z  
for(int i=0;i<nStartPos.length;i++) 2HDWlUTNVO  
fileSplitterFetch.splitterStop(); yz%o?%@  
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} t;t;+M|W  
} n9k-OGJ  
//负责部分文件的抓取 W}WDj:  
**FileSplitterFetch.java ^,Ft7JAn  
*/ UvL=^*tm  
package NetFox; rW*[sLl3  
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import java.io.*; sTxbh2  
import java.net.*; ,fhK  
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public class FileSplitterFetch extends Thread { tjcsT>  
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+_
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String sURL; //File URL H9[0-Ur5  
long nStartPos; //File Snippet Start Position w|-m*v .  
long nEndPos; //File Snippet End Position 4@Bl 1b[<  
int nThreadID; //Thread's ID 12}!oS~_  
boolean bDownOver = false; //Downing is over j!IkU}*c  
boolean bStop = false; //Stop identical &HqBlRo  
FileAccessI fileAccessI = null; //File Access interface f
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException (:RYd6i  
{ L!Gpk)}[i  
this.sURL = sURL; nlc$"(eA[H  
this.nStartPos = nStart; ^a7a_M  
this.nEndPos = nEnd; kXOc)  
nThreadID = id; lXutZ<S[  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 
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} 4!-/m7%eF  
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public void run() *d-JAE  
{ C-^8;xd  
while(nStartPos < nEndPos && !bStop) K!v\r
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{ jN/snU2\0  
@={ qy}  
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try{ Y"TrF(C  
URL url = new URL(sURL); P6`LUyz3  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); bj@f<f`  
httpConnection.setRequestProperty("User-Agent","NetFox"); CxrsP.  
String sProperty = "bytes="+nStartPos+"-"; )eH?3""  
httpConnection.setRequestProperty("RANGE",sProperty); #`%V/#YK  
Utility.log(sProperty); JHJ]BMm  
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InputStream input = httpConnection.getInputStream(); ?BU?c:"f  
//logResponseHead(httpConnection); 
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byte[] b = new byte[1024]; r<DPh5ReY  
int nRead; `6v24?z  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) =0>[-:Z  
{ |W5lhx0U  
nStartPos += fileAccessI.write(b,0,nRead); i({MID)/_  
//if(nThreadID == 1) aX*7tRn_%  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); $]4o!Z  
} n m.5!.  
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Utility.log("Thread " + nThreadID + " is over!"); HE+
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bDownOver = true; PVrNS7 Rk/  
//nPos = fileAccessI.write (b,0,nRead); O{EbL5p  
} /{-J_+u*%  
catch(Exception e){e.printStackTrace ();}
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} !y3X
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} 3o#K8EL  
Ba76~-gK$  
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//打印回应的头信息 =h/61Bl3  
public void logResponseHead(HttpURLConnection con) 0hq\{pw_y*  
{ n]3Z~HoZ  
for(int i=1;;i++) <m%ZDOMa  
{ m" ]VQnQ  
String header=con.getHeaderFieldKey(i); zRB LkrC  
if(header!=null) a@!O}f*  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); |wyua@2  
Utility.log(header+" : "+con.getHeaderField(header)); $v=(`
=  
else }s.\B 
 
break; p@wtT"Y  
} A%~t[
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} "P$')uwE  
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public void splitterStop() gj82qy\:  
{ -'Z-8  
bStop = true; fBKN?]BdN  
} Z*.rv t  
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} WPPDvB  
/`7G7pQ+  
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/* M[L@ej  
**FileAccess.java 8]WcW/1r !  
*//文件访问(定位，写) s 4n<k]d  
package NetFox; i1!Y{  
import java.io.*; 6df`]sc  
q'%!qa+  
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public class FileAccessI implements Serializable{ G'Uq595'-  

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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 o)H| #9h5  
RandomAccessFile oSavedFile; w} r mYQ  
long nPos; J,k.*t:  
#,OiZQJC  
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public FileAccessI() throws IOException ~$YasFEz
 
{ 5Z13s  
this("",0); r(g2&}o\  
} GQ*or>R1  
bs)Ro/7}  
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public FileAccessI(String sName,long nPos) throws IOException 6.vwK3\>~  
{ 4r9AUmJqw  
oSavedFile = new RandomAccessFile(sName,"rw"); 8cj}9}k  
this.nPos = nPos; ngzQVaB9  
oSavedFile.seek(nPos); GZ.KL!,R!  
} cp
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U \jFB*U  
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public synchronized int write(byte[] b,int nStart,int nLen) DOq"=R+  
{ DK#Tr: 7  
int n = -1; QV _aM2  
try{ LqS_%6^  
oSavedFile.write(b,nStart,nLen); z/i&Lpr:  
n = nLen; }L>0}H  
} EH]qYF.  
catch(IOException e)
&& WEBQ  
{ r`PD}6\  
e.printStackTrace (); +SkfT4*U  
} ePTxuCf>  
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return n; !)FKF7'  
} J$,bsMIX  
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} /Y| <0tq  
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/* YH&0Vy#c$  
**SiteInfoBean.java VRUA<x  
*/ 3u9}z+q  
package NetFox; 'w_Qs~6~{  
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public class SiteInfoBean { *Q;?p
hr  
Y\E7nll:.  
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private String sSiteURL; //Site's URL `Yyi;!+0  
private String sFilePath; //Saved File's Path  `dIwBfg_  
private String sFileName; //Saved File's Name aO*v"^oF  
private int nSplitter; //Count of Splited Downloading File KuMH,rXF  
n{"a0O  
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public SiteInfoBean() Oki{)Ssy  
{//nSplitter的缺省值为5 "fu@2y4^  
//default value of nSplitter is 5 *4c5b'u  
this("","","",5); =lx~tSiS  
} _B
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~zQxfl/  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) {6>$w/+~  
{ )-\qo#0l  
sSiteURL= sURL; -K6y#O@@  
sFilePath = sPath; -6# _t  
sFileName = sName; ~g*5."-i  
this.nSplitter = nSpiltter; ;G*)7fi  
k!d<2Qp W  
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} igF<].'V  
0*6Q8`I  
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public String getSSiteURL() Tj!rAMQk  
{ ~F>'+9?Sn  
return sSiteURL; fPG3$<Zr  
} h79~d%-  
h/*@ML+bB8  
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public void setSSiteURL(String value) i>(TPj|  
{ /b410NP5  
sSiteURL = value; 1+qP7 3a^  
} }+K=>.  
6u{%jSA>D\  
]6,D9^{;  
public String getSFilePath() *C.Kdf3w  
{ }|l7SFst  
return sFilePath; %Hu.FS5'  
} #j"GS/y"  
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.d+zF,02Z  
public void setSFilePath(String value) 6+:;Mb_S  
{ 593!;2/@  
sFilePath = value; ,Uy;jk  
} rnBp2'EM  
8( bK\-b  
T[2<_nn=  
public String getSFileName() sk@aOv'*(  
{ d"thM  
return sFileName; 4K,S5^`Gx  
} m,ur{B8 :  
o 80x@ &A:  
{HjJ9ZGQ  
public void setSFileName(String value) c!mMH~#  
{ 6#HnA"I2n  
sFileName = value; N3wy][bo  
} '30JJ0  
`)Y 5L}c=  
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public int getNSplitter() N[N4!k )!$  
{ ."`||@|  
return nSplitter; 7t+H94KG7  
} LVdtI  
nIqF:6/  
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public void setNSplitter(int nCount) X,D ]S@  
{ w{GEWD{&  
nSplitter = nCount; kB=5=#s  
} D[{"]=-  
} VREDVLQT  
olK*uD'`  
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/* <}F(G-kV6  
**Utility.java )M8@|~~  
*/ ,Bj]j -\Y  
package NetFox; vgi`.hk  
.I%B$eH  
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public class Utility {
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public Utility() Sp]ov:]%f  
{ Y@+9Ukd/  
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} ScRK1  
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//线程睡眠 hPUZ{#;n  
public static void sleep(int nSecond) 1[\I9dv2  
{ 61*b|.sl'#  
try{ rY)m
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Thread.sleep(nSecond); *Zn,v-d  
} "@rHGxK  
catch(Exception e) IG~Zxn1o  
{ ]PbwG  
e.printStackTrace (); v+CW([zAx#  
} PmT<S,}L  
} o%K1!'  
pE$*[IvQ'  
//日志 _:JV-lM  
public static void log(String sMsg) <80M$a g  
{  1 K]  
System.err.println(sMsg); ML%JTx0+Z  
} 0UQ DB5u  
m`jGBSlw_  
#q8/=,3EG  
public static void log(int sMsg) _,w*Rv5=  
{ FPEab69  
System.err.println(sMsg); Ad4-aWH  
} ^$<:~qq!  
} }{v0}-~@  
4 &0MB>m  

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/* M->#WGl\B  
**TestMethod.java ZL9|/ PY  
*/ ,.&D{$1W  
package NetFox; 3w! NTvp  
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mOFp!(  
public class TestMethod { 2t7=GA+j  
[ *
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f?"909&  
public TestMethod() fLV@~T|  
{ ///xx/weblogic60b2_win.exe ][~rk?YY  
try{ |^#Z!Hp_Y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5);  5e2yJ R  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); )7Oj  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Z*'_/Grv?  
fileFetch.start(); z0T6a15f!P  
} qnO/4\qq  
catch(Exception e){e.printStackTrace ();} %t$)sg]  
#:
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{3 >`k.w  
} ,f
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public static void main(String[] args) ca%XA|_J  
{ EDg; s-T=  
new TestMethod(); >,f5 5  
} Ex{;&UWm  
} d/E0opv  
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