http断点续传简单实现（java)

/* jK& Nkp  
**SiteFileFetch.java zG&WWc`K  
*/ [6Uudiw  
package NetFox; rd|@*
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import java.io.*; bv.EM  
import java.net.*; Rh!L'?C  
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public class SiteFileFetch extends Thread { ~+sne7 6 U  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 3N(8|wh  
long[] nStartPos; //开始位置 \W3+VG2cA  
long[] nEndPos; //结束位置 I@8+k&nXS  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 v]LFZI5  
long nFileLength; //文件长度 YR$tPe  
boolean bFirst = true; //是否第一次取文件
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boolean bStop = false; //停止标志 P58\+9d_  
File tmpFile; //文件下载的临时信息 s4\SX,  
DataOutputStream output; //输出到文件的输出流 FCsyKdM  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ek Y?  
public SiteFileFetch(SiteInfoBean bean) throws IOException nEjo,   
{ .F{}~K]  
siteInfoBean = bean; {Hktu|  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); a7QlU=\  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); m]+X}|  
if(tmpFile.exists ()) 9'L1KQ  
{ ucIVVT(u  
bFirst = false; T{5M1r  
read_nPos(); 4<=eK7;XR  
} jUV#HT  
else N[|by}@n  
{ BDv|~NHs  
nStartPos = new long[bean.getNSplitter()]; I v 80,hW  
nEndPos = new long[bean.getNSplitter()]; ;j[q?^ b  
} *so6]+)cU  
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} {,n
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public void run() `Gy>tD.#V-  
{ XnNOj>!  
//获得文件长度 7LyV`6{70  
//分割文件 cOj +}Hz58  
//实例FileSplitterFetch qiwQUm{  
//启动FileSplitterFetch线程 $G^H7|PzdC  
//等待子线程返回 \rw'QAi8r  
try{ cG~_EX$  
if(bFirst) vZ1D3ytfG  
{ s5_1}KKCs  
nFileLength = getFileSize(); H
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if(nFileLength == -1) BMtYM{S6  
{ QrrZF.
 
System.err.println("File Length is not known!"); >o=axZNa  
} (_s!,QUe  
else if(nFileLength == -2) ;n:H6cp  
{ |r<.R>  
System.err.println("File is not access!"); $w2[5|^S  
} +E""8kW- Z  
else Z(Ls#hp  
{ r`mzsO-'  
for(int i=0;i<nStartPos.length;i++) +ik N) D  
{ b_)QBE9  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ]ci|$@V  
} (<5'ceF)X  
for(int i=0;i<nEndPos.length-1;i++) B8BY3~}]  
{ ]%ZjD  
nEndPos = nStartPos[i+1]; dxae2 tV  
} )nbyV a  
nEndPos[nEndPos.length-1] = nFileLength; @eG#%6">  
} ^YB\\a9  
} T^f&58{ 7  
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!Cv<>_N).  
//启动子线程 `gA5P %  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; `qYc#_ELv  
for(int i=0;i<nStartPos.length;i++) xr1I8 5kM  
{ 0lJBtk9wn  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), e-T9HM&%P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), fu7[8R"{  
nStartPos,nEndPos,i); ;#Crh}~  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); QKL]O*  
fileSplitterFetch.start(); QtO[g  
} M\$<g  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), y+~Aw"J}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); .,iw2:  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", O+3D 5*  
nEndPos = " + nFileLength); (t"YoWA#m  
// fileSplitterFetch[nPos.length-1].start(); C9^elcdv  
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u.xA}yVS  
//等待子线程结束 U%SNROj  
//int count = 0; =fu_ Jau}  
//是否结束while循环 (vYf?+Kb  
boolean breakWhile = false; =,}!Ns{k  
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while(!bStop) EzY scX.[  
{ b "AHw?5F  
write_nPos(); v*T@<]f3j  
Utility.sleep(500); ;tIIEc  
breakWhile = true; D-;43>yi<  
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for(int i=0;i<nStartPos.length;i++) )="g?E3  
{ gs2&0rnOy\  
if(!fileSplitterFetch.bDownOver) &`9bGO
  
{ }e;p8)]Wl  
breakWhile = false; nh_xbo5L[  
break; 70 DQ/b  
} G#=b6DB  
} S3[oA&  
if(breakWhile) L:];[xa%  
break; sjg
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~  
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//count++; DW;.R<8  
//if(count>4) l>Oe ,`9O  
// siteStop(); PeR<FSF ,i  
} }Q,C;!'"  
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System.err.println("文件下载结束！"); m$e@<~To  
} 8C4@V[sm`  
catch(Exception e){e.printStackTrace ();} B\~3p4S  
} =?QQb>  
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//获得文件长度 -1Ki7|0,  
public long getFileSize() U*#E aL  
{ A 5\"e^>  
int nFileLength = -1; L?pvz}  
try{ JZ*?1S>  
URL url = new URL(siteInfoBean.getSSiteURL()); ,@j&q  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ), x3tTR  
httpConnection.setRequestProperty("User-Agent","NetFox"); =I*ZOE3n  
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int responseCode=httpConnection.getResponseCode(); E9NGdp&-Ah  
if(responseCode>=400) Nl>
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{ 7B>cmi  
processErrorCode(responseCode); L&F\"q9q71  
return -2; //-2 represent access is error UmHb-uk ;  
} ny;)+v?mN\  
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String sHeader; u K&_IE}  
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for(int i=1;;i++) fxCPGj  
{ KLM^O$=  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); I2!&="7@  
//Utility.log(in.readLine()); pPqbD}p  
sHeader=httpConnection.getHeaderFieldKey(i); tw^.(m5d  
if(sHeader!=null) A-NC,3  
{ )e$-B]>7z  
if(sHeader.equals("Content-Length")) ~<Qxw>S#  
{ EwJn1Mvq  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ; yC`5  
break; }z%/6`7)|  
} TEy.zzt  
} k-p7Y@`+a  
else ]0nC;|]@Lx  
break; H5rNLfw '  
} +R jD\6bJb  
} h3ZL0Fi*  
catch(IOException e){e.printStackTrace ();} G?X,Y\Lp  
catch(Exception e){e.printStackTrace ();} ,}$x'8v  
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Utility.log(nFileLength); UVi/Be#|  
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return nFileLength; <.]&FPJ  
} GoGgw]h>x  
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//保存下载信息（文件指针位置） PbC>v  
private void write_nPos() }Z%{QJ$z  
{ K":tr~V;  
try{ mr\L q~*c  
output = new DataOutputStream(new FileOutputStream(tmpFile)); t,Rn  
output.writeInt(nStartPos.length); z+`)|c4-  
for(int i=0;i<nStartPos.length;i++) Lr]Hvd  
{ B~?Q. <M  
// output.writeLong(nPos); U0=zuRr n  
output.writeLong(fileSplitterFetch.nStartPos); 246!\zf  
output.writeLong(fileSplitterFetch.nEndPos); /-9+(  
} "PP0PL^5F  
output.close(); JH,fg K+[  
} m|
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catch(IOException e){e.printStackTrace ();} x"=q+sA  
catch(Exception e){e.printStackTrace ();} ~ZIRCTQ"  
} MPw7!G(qj  
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}Bg<Fm  
//读取保存的下载信息（文件指针位置） icbYfgQ  
private void read_nPos() YZ+g<HXB  
{ $CV'p/^En  
try{ >dH*FZ:c  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Uv$u\D+@[  
int nCount = input.readInt(); 4B,A+{3yL  
nStartPos = new long[nCount]; / =<ul-K  
nEndPos = new long[nCount]; tUnVdh6L.B  
for(int i=0;i<nStartPos.length;i++) QiL  
{ tXuxTVhoT  
nStartPos = input.readLong(); _Pm}]Y:_  
nEndPos = input.readLong(); `^Sq>R!;  
} Z0@ImhejuB  
input.close(); soCHwiE  
} =5#Jsn?U  
catch(IOException e){e.printStackTrace ();}  ~&jCz4M  
catch(Exception e){e.printStackTrace ();} fXQRsL8 ]  
} "C|l3X'  
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private void processErrorCode(int nErrorCode) PA[Rhoit,  
{ L-TVe  
System.err.println("Error Code : " + nErrorCode); 'Z9F0l"Nr  
} I=-;*3g6  
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//停止文件下载 H(m+rk  
public void siteStop() Um|Tf]q  
{ BGjTa.
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bStop = true; |ZzBCL8q  
for(int i=0;i<nStartPos.length;i++) -JQg{A  
fileSplitterFetch.splitterStop(); +Enff0 =+  

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} d8I:F9  
} ]jrxrUl  
//负责部分文件的抓取 w#b2iE+Bw  
**FileSplitterFetch.java }e@-
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*/ nJ@
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package NetFox; 9D21e(7X  
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import java.io.*; ' qVa/GJ  
import java.net.*; N/=3Bs0y-  
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public class FileSplitterFetch extends Thread { 1i2O]e!  
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String sURL; //File URL %tLq&tyeY  
long nStartPos; //File Snippet Start Position P ie!Su`  
long nEndPos; //File Snippet End Position |0mI3r  
int nThreadID; //Thread's ID h!]A(T\J  
boolean bDownOver = false; //Downing is over K@hUif|([  
boolean bStop = false; //Stop identical &9{BuBO[  
FileAccessI fileAccessI = null; //File Access interface oPBjsQ  
x=)$sD-3  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException gV;GC{pY  
{ '+wTrW m~j  
this.sURL = sURL; /L^dHI]Q  
this.nStartPos = nStart; }5Uf`pM8  
this.nEndPos = nEnd; 8m0sEV>  
nThreadID = id; >S]')O$c  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 V|`|CVFo
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} Zv93cv  
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public void run() @9a=D<'>  
{ s,x]zG"  
while(nStartPos < nEndPos && !bStop) A@r,A?(  
{ $Plk4 o*g  
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try{ 4N&}hOM'S  
URL url = new URL(sURL); q4oZJ-`  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 470Pig>I8  
httpConnection.setRequestProperty("User-Agent","NetFox"); x ,W+:l9~s  
String sProperty = "bytes="+nStartPos+"-"; Po3W+;@  
httpConnection.setRequestProperty("RANGE",sProperty); KMcP!N.I  
Utility.log(sProperty); :Ib\v88WIv  
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InputStream input = httpConnection.getInputStream(); 7&1: ]{_  
//logResponseHead(httpConnection); EK_^#b  
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byte[] b = new byte[1024]; 0M?}S~p]  
int nRead; dGe  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) CS49M  
{ yk/XfwQ5  
nStartPos += fileAccessI.write(b,0,nRead); %+~0+ev7r  
//if(nThreadID == 1) +L6d$+  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?a@l.ZM*  
}
v},sWjv  

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\ :.p8`  
Utility.log("Thread " + nThreadID + " is over!"); h>?OWI  
bDownOver = true; kTV D4Z=  
//nPos = fileAccessI.write (b,0,nRead); zAewE@N#_  
} 7Z_iQ1  
catch(Exception e){e.printStackTrace ();} )SuJK.IF  
} 3]acfCacC  
} VbjW$?  
p WHu[Fu  
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//打印回应的头信息 uHYI :(O  
public void logResponseHead(HttpURLConnection con) q`hg@uwA{`  
{ 75y#^pD?c  
for(int i=1;;i++) b%(0AL  
{ <>TBM^  
String header=con.getHeaderFieldKey(i); yyc&'J  
if(header!=null) KMV!Hqkk  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); O9Aooe4W=  
Utility.log(header+" : "+con.getHeaderField(header)); \=)h6AG  
else (!s[~O6  
break; jk@]d5  
} d<o  
} P;34Rd  
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public void splitterStop() _PF><ODX2  
{ q2y:bqLWl  
bStop = true; V|= 1<v  
} .;'xm_Gw<  
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} <S qbj;  
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/* Ts\7)6|F  
**FileAccess.java 6C:Lq%}  
*//文件访问(定位，写) )'JSu=E
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package NetFox; 6x0>E^~  
import java.io.*; hjE9[{K  
9pXFC9  
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public class FileAccessI implements Serializable{ i!NGX  
:.<&Y=^  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 @cON"(  
RandomAccessFile oSavedFile; \xt!b^d0  
long nPos; 'py k  
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public FileAccessI() throws IOException ?~!h N,h  
{ &m`  
this("",0); 4
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} ep5aBrN]"  
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public FileAccessI(String sName,long nPos) throws IOException N`M5`=.  
{ X*T9`]l6  
oSavedFile = new RandomAccessFile(sName,"rw"); &("?6%GC  
this.nPos = nPos; &7 ,wdG  
oSavedFile.seek(nPos); T*oH tpFj#  
} aD4ln]sFxG  
,#crtX  
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public synchronized int write(byte[] b,int nStart,int nLen) .+y#7-#6  
{ zMa`olTZ  
int n = -1; qcK)J/K"  
try{ ^/c|s!U^  
oSavedFile.write(b,nStart,nLen); U5Y*xm<  
n = nLen; @:Ns`+ W*  
} -$7Jc=:>  
catch(IOException e) Z"n]y4h  
{ 2dC)%]aLme  
e.printStackTrace (); |k8;[+  
} ?mV[TM{p  
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return n; _7Z$"  
} t[<=QK  
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} !54%}x)3  
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/* '!_o`t@  
**SiteInfoBean.java uuq?0t2Z  
*/ D!:Qy@Zw  
package NetFox; bc+'n  
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public class SiteInfoBean { \UXQy{Ex  
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private String sSiteURL; //Site's URL 3LEN~N}  
private String sFilePath; //Saved File's Path DU;]Q:r{  
private String sFileName; //Saved File's Name A)qOJ(OEz  
private int nSplitter; //Count of Splited Downloading File '8dqJ`Gj  

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&P\T{d2"  
public SiteInfoBean() 9Vp$A$7M  
{//nSplitter的缺省值为5 }>grGr%oR  
//default value of nSplitter is 5 U8moVj8w1  
this("","","",5); `aCcTs7~]p  
} Q[}mH: w  

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\\[P^ tsF  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Ar|_UV>Zf  
{ Wjj'yqBO^  
sSiteURL= sURL; }b1P!xb!A  
sFilePath = sPath; $Q?UyEi  
sFileName = sName; Lg'z%pi
 
this.nSplitter = nSpiltter; Cu0/TeEM  
*{XbC\j  
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} EB)0 iQ  
p}C3<
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public String getSSiteURL() `/0FXb 8h  
{ tf>?;  
return sSiteURL; ](%-5G1<  
} r1,RloyZS  
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public void setSSiteURL(String value) grv 3aa@  
{ xNT[((  
sSiteURL = value; (Y-
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} k+_pj k  
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public String getSFilePath() dD#A.C,Rz  
{ 3Y>!e#  
return sFilePath;
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} d kPfdK}G  
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public void setSFilePath(String value) 1,Y-_e)  
{ (d@lG*K  
sFilePath = value; s$mcIMqs  
} ujHqwRh  
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public String getSFileName() ,*Sj7qb#  
{ y+@7k3"  
return sFileName;
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} S?;&vs9j  
9^ )=N=wV  
e
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public void setSFileName(String value) 0&Zm3(}  
{
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sFileName = value; eqYa`h@g^  
} fAYm3+.l3  
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public int getNSplitter() l,L#y4#  
{ *V5R[   
return nSplitter; gaVWfG  
} 7)z^*;x  
m\[r6t]V  
98G>I(Cw%  
public void setNSplitter(int nCount) HjLY\.S  
{ L= hPu#&/  
nSplitter = nCount; YS%HZFY, "  
} gTm[<Y  
} ,{7Z OzA  
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7@5}WNr  
/* 9tWu>keu  
**Utility.java iq
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*/ L3,p8-d9Z  
package NetFox; j$siCsF  
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public class Utility { *e!0ZB3J  
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public Utility() )mS Aog<  
{ gm\P`~+o  
>`SIB; &>j  
"I}3*s9Q-  
} 44b;]htv  
Z-.`JkKd8  
//线程睡眠 m onqaSF  
public static void sleep(int nSecond) 0
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{ 5_9mA4gs@  
try{ V`m'r+ Y  
Thread.sleep(nSecond); EE=!Y NP]  
} LW 8LD|@  
catch(Exception e) h%9#~gJ})  
{ Hcq?7_)  
e.printStackTrace (); l`4hWs\I  
} t32 FNg  
} +QGZ2_vW  
2c LIz@  
//日志 R#DnV[!\  
public static void log(String sMsg) U@Y0z.Y  
{ ' cR||VX  
System.err.println(sMsg); +:+q,0~*]  
} ^9UKsy/q  
}vgeQh-G  
uzr(gFd  
public static void log(int sMsg) Q,S~+bD(z  
{ j|c  
System.err.println(sMsg); ;*Ldnj;B  
} .Cwgl  
} Qo+I98LX[  
h(l4\)  
]
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/* 2x<,R/}  
**TestMethod.java e3oHe1"hP  
*/ SvLI%>B
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package NetFox; >08'+\~:b  
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public class TestMethod { F<39eDNpz  
-|YG**i/  
)!z<q}i5  
public TestMethod() n** W  
{ ///xx/weblogic60b2_win.exe dZK/v  
try{ T)?:
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7u73v+9qn:  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); |WwC@3)  
SiteFileFetch fileFetch = new SiteFileFetch(bean); gqJSz}'  
fileFetch.start(); ROsR;C0!  
} H]As2$[  
catch(Exception e){e.printStackTrace ();} 8w/$!9[  
W;!
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;5Spdi4w  
} H\H4AAP5F$  
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public static void main(String[] args) z-ns@y(f@X  
{ (dmLEt  
new TestMethod(); ?gD^K,A Hd  
} c_wvuKa  
} o{MF'B#  
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