http断点续传简单实现（java)

/* M^r1S  
**SiteFileFetch.java YaKeq5%y  
*/ TgmnG/Z  
package NetFox; ;CmS ~K:  
import java.io.*; Y2ZT.l  
import java.net.*; G~2jUyv  
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public class SiteFileFetch extends Thread { aWWU4xe  
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SiteInfoBean siteInfoBean = null; //文件信息Bean rV R1wsaL  
long[] nStartPos; //开始位置 Mc09ES  
long[] nEndPos; //结束位置 5Iy;oZ  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 K]s[5  
long nFileLength; //文件长度 C":32_q  
boolean bFirst = true; //是否第一次取文件 JEahGzO  
boolean bStop = false; //停止标志 &,c``z  
File tmpFile; //文件下载的临时信息 ZUVA EH%  
DataOutputStream output; //输出到文件的输出流 PE}:ybsX  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） T
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public SiteFileFetch(SiteInfoBean bean) throws IOException G-xDN59K  
{ P"y`A}Bx  
siteInfoBean = bean; H:t$'kb`  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); E9Np0M<  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); b\vKJ2  
if(tmpFile.exists ()) )vjh~ybZ  
{ ;V*R*R  
bFirst = false; ]h* c,.  
read_nPos(); ]>LhkA@V  
} 4)h]MOZ  
else )Dw,q~xgg0  
{ 8\^}~s$$A
 
nStartPos = new long[bean.getNSplitter()]; p^%YBY#,H  
nEndPos = new long[bean.getNSplitter()];  FT#8L  
} tyXuG<  
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} kP#B5K_U|  
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public void run() L+Xc-uv["p  
{ *1p|5!4c  
//获得文件长度 5R
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//分割文件 \6E|pbJ}x  
//实例FileSplitterFetch 0B@SN)<kH  
//启动FileSplitterFetch线程 y.#")IAF  
//等待子线程返回 Vr6@>@SC  
try{ U3T#6Rptl  
if(bFirst) cC=[Saatsf  
{ Xu<k3oD7  
nFileLength = getFileSize(); f&eK|7J_Yf  
if(nFileLength == -1) WG6FQAo^8  
{ f,V<;s  
System.err.println("File Length is not known!"); @ezH'y-v  
} \m7-rV6r  
else if(nFileLength == -2) R< ,`[*Z  
{ -8eoNzut  
System.err.println("File is not access!"); :3XA!o&.T3  
} @&%'4j&+  
else 2z6yn?'&L  
{ <3xyjX'NE  
for(int i=0;i<nStartPos.length;i++) x_|UPF  
{ 4}_j`d/8|  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ~$iIVJ`  
} P3cRl']  
for(int i=0;i<nEndPos.length-1;i++) _LMM,!f  
{ !>{G,\^=pT  
nEndPos = nStartPos[i+1]; TH; R  
} & -{DfNKc  
nEndPos[nEndPos.length-1] = nFileLength; {5%5}[/x  
} %\D)u8}  
} C~nzH,5  
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//启动子线程 <,Ue 0  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ?ooe'V@  
for(int i=0;i<nStartPos.length;i++) wfU7G[  
{ l>Z5 uSG  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .z)%)PVV  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), w[9|cgCY  
nStartPos,nEndPos,i); PZE
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 0Fk5kGD,&K  
fileSplitterFetch.start(); :*i
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} 56+s~hG  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Y?  x,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); NLUT#!Gr  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", P|.]DJ  
nEndPos = " + nFileLength); ]w;rfn9D  
// fileSplitterFetch[nPos.length-1].start();  :rHJ4Tl  
J8S'/y(LE<  

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//等待子线程结束 wF <n=  
//int count = 0;
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//是否结束while循环 3Mxp)uG/  
boolean breakWhile = false; )-0kb~;|  
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while(!bStop) (8Bk;bd  
{ x^kp^ /f  
write_nPos(); $^OvhnL/  
Utility.sleep(500); =+U `-J}g  
breakWhile = true; d]:I(9K  
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for(int i=0;i<nStartPos.length;i++) Fs{x(_LOr  
{ q;<h[b?  
if(!fileSplitterFetch.bDownOver) ~aMlr6;  
{ A*2 bA  
breakWhile = false; ^cczJOxB  
break; ^aH\7J@Y  
} 5jd,{<  
} 4a'N>eDR  
if(breakWhile) b~'"^ Bts*  
break; V,q](bg  
`S6x<J&T\/  
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//count++; JHz [7  
//if(count>4) r30 <(nF  
// siteStop(); <\NY<QIwFw  
} R]OpQ[k  
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System.err.println("文件下载结束！"); #9X70|f  
} /LO-HnJ  
catch(Exception e){e.printStackTrace ();} ppZDGpp  
} H *[_cqnv  
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//获得文件长度 R
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public long getFileSize() m=}B,']O  
{ &;D8]7d
 
int nFileLength = -1; I_<I&{N>  
try{ lTd #bN  
URL url = new URL(siteInfoBean.getSSiteURL()); x7~r,x(xM  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); p1&b!*o-&  
httpConnection.setRequestProperty("User-Agent","NetFox"); 7g%E`3)"  
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int responseCode=httpConnection.getResponseCode(); (vb SM}P  
if(responseCode>=400) MC<PM6w  
{ W}5xmz  
processErrorCode(responseCode); T(t+ iv  
return -2; //-2 represent access is error A<1hOSCz\  
} n}'=yItVL1  
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String sHeader; S<4c r  
s
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for(int i=1;;i++) poToeagZ~Q  
{ u/M+u;  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); w,h`s.AN  
//Utility.log(in.readLine()); |962G1.  
sHeader=httpConnection.getHeaderFieldKey(i); ]`kmjn  
if(sHeader!=null) !Cr(Pe]  
{ DV _2P$tT|  
if(sHeader.equals("Content-Length")) .u4 W /  
{ 7T1=q{#M  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); -?mfE+kt  
break; 8Le||)y,\  
} (>r[-Bft  
} <-[wd.M_  
else pov)Z):}G<  
break; gLy&esJl1  
} #wV8X`g  
} a'2$
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catch(IOException e){e.printStackTrace ();} O+]Ifm[  
catch(Exception e){e.printStackTrace ();} |h;0H`  
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Utility.log(nFileLength); ^R# E:3e  
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return nFileLength; /(iFcMT  
} N7O-2Z *  
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//保存下载信息（文件指针位置） xO&eRy?%  
private void write_nPos() 8$0rR55  
{ fp+gyTnd3  
try{ H[S%J3JI  
output = new DataOutputStream(new FileOutputStream(tmpFile)); qYlhlHD  
output.writeInt(nStartPos.length); paKSr|O  
for(int i=0;i<nStartPos.length;i++) k} |   
{ %O!v"Xh  
// output.writeLong(nPos); %`&2+\`  
output.writeLong(fileSplitterFetch.nStartPos); [uI|DUlI6o  
output.writeLong(fileSplitterFetch.nEndPos); Bh;7C@dq  
} @JyK|.b
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output.close(); 9Hf9VC3  
} v"#mzd.tW  
catch(IOException e){e.printStackTrace ();} X22[tqg;&  
catch(Exception e){e.printStackTrace ();} c.>oe*+  
} :TJv=T'p'  
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//读取保存的下载信息（文件指针位置） @te
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private void read_nPos() >_|O1H./4  
{ EUN81F?  
try{ Ry%Mej:  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); .6`9H 1  
int nCount = input.readInt();
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nStartPos = new long[nCount]; d` jjGEj  
nEndPos = new long[nCount]; e>(<eu~P  
for(int i=0;i<nStartPos.length;i++) !V i@1E  
{ SjwyLc  
nStartPos = input.readLong(); X@K-^8  
nEndPos = input.readLong(); P!+'1KR  
} cm&I* 0\  
input.close(); `C$:Yf]%nG  
} bO'Sgc[]  
catch(IOException e){e.printStackTrace ();} @I_8T$N=  
catch(Exception e){e.printStackTrace ();} =8; {\  
} E|6VX4`+  
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private void processErrorCode(int nErrorCode) \E%'Y  
{ E ,|xJjh  
System.err.println("Error Code : " + nErrorCode); qoj$]   
} S
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//停止文件下载 DGAX3N;r6{  
public void siteStop() c6X}2a'  
{ lzYnw)Pv  
bStop = true; = c>Qx"Sw  
for(int i=0;i<nStartPos.length;i++) *:L?#Bw  
fileSplitterFetch.splitterStop(); E}40oID  
/4` 0?/V  
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} Qzlo'e1  
} Axe8n1*y  
//负责部分文件的抓取 rzh#CnL3  
**FileSplitterFetch.java pO ml8SQf  
*/ %2XHNW  
package NetFox; `eIenA  
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@>E2?CV  
import java.io.*; 2ioQb`=  
import java.net.*; \Dd-
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{ T-'t/0e(  
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public class FileSplitterFetch extends Thread { Y0_),OaY  
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String sURL; //File URL N(y\dL=v  
long nStartPos; //File Snippet Start Position q^r#F#*1l  
long nEndPos; //File Snippet End Position %=/)  
int nThreadID; //Thread's ID ~Uxsn@nLr  
boolean bDownOver = false; //Downing is over
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boolean bStop = false; //Stop identical Fl1;;F  
FileAccessI fileAccessI = null; //File Access interface = Wu *+paQ  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ,:Lb7bFv>  
{ ?zQA
  
this.sURL = sURL; K9OY
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this.nStartPos = nStart; M $Es%  
this.nEndPos = nEnd; .8P.)%  
nThreadID = id; p TeOW9  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 "87ghj_}  
} K00 87}H  
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public void run() -
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{ sK7+Q  
while(nStartPos < nEndPos && !bStop) `kU/NKq  
{ A` AaTP  
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try{ nSkPM5\TI  
URL url = new URL(sURL); jSwf*u  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();  \o/n  
httpConnection.setRequestProperty("User-Agent","NetFox"); uU:CR>=AKW  
String sProperty = "bytes="+nStartPos+"-"; 
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httpConnection.setRequestProperty("RANGE",sProperty); '*?WU_L(g  
Utility.log(sProperty); -*m+(7G\  
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InputStream input = httpConnection.getInputStream(); 9\]^|?zQ`  
//logResponseHead(httpConnection); yq NzdzX  
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byte[] b = new byte[1024]; `/~8}Y{  
int nRead; -tyK~aasQ  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 4=Krq6{  
{ H8`(O"V  
nStartPos += fileAccessI.write(b,0,nRead); 1$81E.  
//if(nThreadID == 1) V2i@.@$j  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _<NMyRJo  
} W~p/,HcM  
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Utility.log("Thread " + nThreadID + " is over!"); m/qbRk68s  
bDownOver = true; /Ne<V2AX  
//nPos = fileAccessI.write (b,0,nRead); W@Lu;g.Yc  
} ?HV`| Cw  
catch(Exception e){e.printStackTrace ();} X_g 3rv1J  
} I=.z+#Y  
} ZG du|  
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//打印回应的头信息 [w&$|h:;  
public void logResponseHead(HttpURLConnection con) +C(/Lyo}  
{ EB_NK  
for(int i=1;;i++) d R]Q$CJ  
{ o`q_wdy?  
String header=con.getHeaderFieldKey(i); YcN!T"wJ@  
if(header!=null) C,pJ`:P  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); '^FGc  
Utility.log(header+" : "+con.getHeaderField(header)); lME)?LOI  
else /M*a,o  
break; zdEPDdB  
} }LijnHH.  
} LI6hEcM=  
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public void splitterStop() yT#{UA^  
{ 't9hXzAfW  
bStop = true; W!"}E%zx  
} )"m!YuSY  
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} .^m>AKC0cX  
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/* &09U@uc$  
**FileAccess.java lZrVY+D  
*//文件访问(定位，写) YTjkPj:  
package NetFox; ]wWPXx[>/  
import java.io.*; WwUv5GZTW  
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public class FileAccessI implements Serializable{ @j4U^"_QB  
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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 jh.@-  
RandomAccessFile oSavedFile; kee|42E  
long nPos; f7'q-  
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public FileAccessI() throws IOException F|HJH"2*&q  
{ 6O22P?v  
this("",0); \J6hI\/4^  
} &V<W>Y>|l*  
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public FileAccessI(String sName,long nPos) throws IOException ,.o<no  
{ U7DCx=B  
oSavedFile = new RandomAccessFile(sName,"rw"); DtEwW
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this.nPos = nPos; $L2%u8}8:  
oSavedFile.seek(nPos); nxJee=qH  
} o8Z[+;  
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public synchronized int write(byte[] b,int nStart,int nLen) ;kJu$U  
{ 2Gs$?}"a  
int n = -1; .?>5-od2  
try{ snt(IJQ  
oSavedFile.write(b,nStart,nLen); 7 uarh!  
n = nLen; n 8pt\i0  
} _6Eu2|vM&  
catch(IOException e) D>!6,m2  
{ eJo3 MK  
e.printStackTrace (); /LM4-S  
} rO:
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z 8*8OWM  
return n; KnNh9^4"\2  
} }rdIUlVO\  
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}I!hOD>]O  
} P N*JR  
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/* EOoZoVdzx  
**SiteInfoBean.java i0s6aAhgJ  
*/ zj|/ CxV  
package NetFox; 3<?XTv-  
G8IY#  
R <"6ojn  
public class SiteInfoBean { oQ7]=|  
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private String sSiteURL; //Site's URL b`_w])Y@  
private String sFilePath; //Saved File's Path &VBd~4|p  
private String sFileName; //Saved File's Name 5`<eKwls  
private int nSplitter; //Count of Splited Downloading File s:AkkkF  
V >,Z-&.%  
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public SiteInfoBean() Cj*-[EL<  
{//nSplitter的缺省值为5 9%IlW  
//default value of nSplitter is 5 1KYN>s:  
this("","","",5); a?
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} Q8MS,7y/  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) hGf-q?7  
{ {FI\~q  
sSiteURL= sURL; vSW L$Y2  
sFilePath = sPath; Y?#i{ixX6n  
sFileName = sName; [ "xn5lE  
this.nSplitter = nSpiltter; <fdPLw;@e4  
{$M;H+Foh  
k?VQi5M  
} V5D`eX9  
@:x"]!1  
ap}5ElMR  
public String getSSiteURL() MbXq`%  
{ fRm}S>Nibb  
return sSiteURL; 5v^L9!`@%v  
} qXXGF_Q  
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public void setSSiteURL(String value) {5%/T,  
{ +^6}   
sSiteURL = value; oY`qInM_  
} C
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public String getSFilePath() $gMCR b,  
{ %So]3;'  
return sFilePath; XV'fW~j\  
} yW.COWL=)  
!~
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public void setSFilePath(String value) JLb6C52  
{ x:t<ZG&Xwg  
sFilePath = value; mo1 puU  
}
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public String getSFileName() 4(vyp.f  
{ 0p fnV%  
return sFileName; 2:$ k  
} uG

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public void setSFileName(String value) ,M3z!=oIGn  
{ z#<P}}  
sFileName = value; ~DLIzg7p!  
} 'Zk<l#"}  
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public int getNSplitter() F?Or;p5`Y  
{ (OQ?<'Qa  
return nSplitter; sXl ??UGe  
} jiIST^Zq#t  
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v9}[$HWx  
public void setNSplitter(int nCount) H]&!'\aUz  
{  d^39
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nSplitter = nCount; ]Qi,j#X  
} =:h3w#_c  
} S=gW(c2'  
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/* ] mj v;C  
**Utility.java SZVV40w  
*/ "E*8h/4u  
package NetFox;  }sMW3'V  
{U <tc4^  
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public class Utility { !Y;<:zx5  
)-&nxOP  
>,h1N$A+  
public Utility() s?O&ZB2GM[  
{ b?kPN:U#N/  
2/tb6' =  
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} 1&|Dsrj  
2 X<nn  
//线程睡眠 \Tq"mw9P  
public static void sleep(int nSecond) kqB\xlS7k  
{ "@/ba!L+  
try{ ]Sta]}VQ  
Thread.sleep(nSecond); p[YWSjf  
} wL<j:>Ke[3  
catch(Exception e) =aow d4t  
{ '\*A"8;h  
e.printStackTrace (); s!h5hwBY  
} 1<uwU(  
} tE!'dpG5)  
0&`}EXe<f  
//日志 #t5juX9Ho9  
public static void log(String sMsg) 9YSVK\2$  
{  3t  
System.err.println(sMsg); ;]h.m)~|  
} ,L-C(j  
3.)_uo0;o  
*5wv%-  
public static void log(int sMsg) 3c 28!3p  
{  b~!om  
System.err.println(sMsg); ug6r]0]  
} ||a`fH  
} T|f_~#?eV  
Tcs3>lJ}  
Q=.g1$LP  
/* aBCOGtf  
**TestMethod.java q<}PM  
*/ =mJ
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package NetFox; DS 1JF  
#v qz{R~nM  
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public class TestMethod { k E_ky)  
oWcACs3fB  
-q(:%;  
public TestMethod() luF#OPC  
{ ///xx/weblogic60b2_win.exe OQ|,-  
try{ G4yUC<TqBP  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); --/-D5  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); >H?uuzi  
SiteFileFetch fileFetch = new SiteFileFetch(bean); w$% BlqN  
fileFetch.start(); }9Qf#&o  
} ^%zNa6BL  
catch(Exception e){e.printStackTrace ();} )
b (X  
x=3I)}J(kn  
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} a&:>Ped"  
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public static void main(String[] args) Et0&E  
{ y(a}IM3~  
new TestMethod(); tnRJ#[Io  
} 'WnpwY  
} O<iI  
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