http断点续传简单实现（java)

/* Gn;@{
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**SiteFileFetch.java xG;-bJu  
*/ OM{WI27  
package NetFox; inlk++Og  
import java.io.*; )Fb>8<%  
import java.net.*; 4[r/}/iGo  
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public class SiteFileFetch extends Thread { (MHAJ]Rx  
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SiteInfoBean siteInfoBean = null; //文件信息Bean GUQ{r!S  
long[] nStartPos; //开始位置 T)\"Xj  
long[] nEndPos; //结束位置 r\;ut4wy  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 W-/}q0h  
long nFileLength; //文件长度 j5I`a 1j`  
boolean bFirst = true; //是否第一次取文件 vf4{$Oag  
boolean bStop = false; //停止标志 Q]o C47(  
File tmpFile; //文件下载的临时信息 ItVugI(^ C  
DataOutputStream output; //输出到文件的输出流 $H$j-)\D  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） hVUP4 A  
public SiteFileFetch(SiteInfoBean bean) throws IOException `-3o+ID\  
{ _4cvX  
siteInfoBean = bean; <_(/X,kBK  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); c)0amM  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); \ u_ui  
if(tmpFile.exists ()) z#F.xVg'  
{ DS|KkTy3  
bFirst = false; sKyPosnP  
read_nPos(); fg#x7v4O  
} @* il3h,  
else ^}f -!nf[  
{  )J?{+3  
nStartPos = new long[bean.getNSplitter()]; 0kDK~iT  
nEndPos = new long[bean.getNSplitter()]; -7!&@wuQ  
} Lr`
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} /.M+fr S  
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public void run() -)vEWn$3<  
{ 2
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//获得文件长度 !gnj]k&/c  
//分割文件 o->\vlbD  
//实例FileSplitterFetch $Ci0I+5w  
//启动FileSplitterFetch线程 Zf7&._y.  
//等待子线程返回 hp"L8w  
try{ e|4&b@  
if(bFirst) *._|
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{ Dup;e&9g  
nFileLength = getFileSize(); [31p&FxM  
if(nFileLength == -1) 4d
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{ PR|R`.QSs  
System.err.println("File Length is not known!"); ,#W  
} s(
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else if(nFileLength == -2) D#S\!>m  
{ 6!^[];%xN  
System.err.println("File is not access!"); 8P: Rg%0)  
} jPnM>=  
else }3R13  
{ )bx_;9Y{  
for(int i=0;i<nStartPos.length;i++) RllY-JBO  
{ m`6Yc:@E  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); W(RF n`g\  
}  Xtq{%  
for(int i=0;i<nEndPos.length-1;i++) @Mvd'.r<;  
{ i ZL2p>  
nEndPos = nStartPos[i+1]; c"!lwm3b  
} |#l=  
nEndPos[nEndPos.length-1] = nFileLength; Z>)][pL  
} 1y^K/.5-  
} #y|V|nd
 
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//启动子线程 0ult7s}  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; '&;yT[  
for(int i=0;i<nStartPos.length;i++) aQ j*KMc  
{ `MP|Ovns:H  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), fA48(0p  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 2FD=lR?6  
nStartPos,nEndPos,i); v}^5Rp&m  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 22(*J<  
fileSplitterFetch.start(); vILy>QS)  
} x_
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ":3 VJ(eY  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); r3rxC&  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", drwg
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nEndPos = " + nFileLength); 3\;27&~gV  
// fileSplitterFetch[nPos.length-1].start(); x{}z ;yG  
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//等待子线程结束

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//int count = 0; I|$ RJkD  
//是否结束while循环 A$g+K,.l  
boolean breakWhile = false; G1 o70  
:`)~-`_  
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while(!bStop) PN+G:Qv  
{ hl&-\dc+  
write_nPos(); \RQ='/H*  
Utility.sleep(500); <ktzT&A  
breakWhile = true; 1p`+  
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for(int i=0;i<nStartPos.length;i++) 6B$q,"%S@  
{ JFL>nH0mk.  
if(!fileSplitterFetch.bDownOver) Wl^R8w#Z$  
{ m"c :"I6  
breakWhile = false; TaJB4zB  
break; 4(?G6y)  
} <b+[<@wS  
}
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if(breakWhile) b=a!j=-D  
break; ea=83 Zj  
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//count++; &$`hQgi  
//if(count>4) {+zJI-XN/  
// siteStop(); *5$&`&,  
} AgF5-tz6x  
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System.err.println("文件下载结束！"); bt+,0\Vg5  
} _nT{g  
catch(Exception e){e.printStackTrace ();} 3-40'$lE  
} +w|9x.&W  
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7  
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//获得文件长度 D}Ilyk_uUw  
public long getFileSize() F="z]C;u  
{ V%
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int nFileLength = -1; 'k&?DZ!  
try{ .DJDpP)M  
URL url = new URL(siteInfoBean.getSSiteURL()); f<y&\'3  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 'UM!*fk7C  
httpConnection.setRequestProperty("User-Agent","NetFox"); bAxTLIf  
+?RGta'%k  
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int responseCode=httpConnection.getResponseCode(); !rxp?V n -  
if(responseCode>=400) MQ][mMM;w  
{ j&6
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processErrorCode(responseCode); \o3"~\|6C  
return -2; //-2 represent access is error j_?cpm{~ml  
} FgA//)1  
&
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String sHeader; jj\[
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for(int i=1;;i++) ;~HNpu$  
{ 1H:ea7YVU  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); oL/o*^  
//Utility.log(in.readLine()); (U.**9b;  
sHeader=httpConnection.getHeaderFieldKey(i); Tc ZnmN  
if(sHeader!=null) w'Z!;4E0  
{ 7x.%hRk  
if(sHeader.equals("Content-Length")) pt:;9hA  
{ {j(4m  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); >3;^l/2c  
break; ](r ^.
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} 2xmk,&s  
} HOYq?40.R  
else 5!fSW2N  
break; ^6/j_G  
} "2n;3ByR  
} i8V0Ty4~N  
catch(IOException e){e.printStackTrace ();} ]S8LY.Az5  
catch(Exception e){e.printStackTrace ();} n~z\?Y=*  
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Utility.log(nFileLength); YaFcz$GE_  
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return nFileLength; [J\DB)V/  
} +h[e0J|v{  
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//保存下载信息（文件指针位置） R$b,h  
private void write_nPos() $"fo^?d/s  
{ @vH2Vydu  
try{ \v`#|lT$  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ^/KfH&E  
output.writeInt(nStartPos.length); `
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for(int i=0;i<nStartPos.length;i++)
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{ +802`eax  
// output.writeLong(nPos); LZWS^77  
output.writeLong(fileSplitterFetch.nStartPos); hN4VlNKu  
output.writeLong(fileSplitterFetch.nEndPos); |1V2tx  
} j8HOc(  
output.close(); [%.18FWI  
} nlfPg-78B+  
catch(IOException e){e.printStackTrace ();} 4UCwT1  
catch(Exception e){e.printStackTrace ();} nTZ> |R)  
} S!j^|!  
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//读取保存的下载信息（文件指针位置） N^$9;CKP=  
private void read_nPos() me./o(!?  
{ 2,AaP*,  
try{ D3?N
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); $v&C@l \  
int nCount = input.readInt(); |QYZRz  
nStartPos = new long[nCount]; jKt-~:  
nEndPos = new long[nCount]; J/S{FxNe]  
for(int i=0;i<nStartPos.length;i++) ^@_).:oX7  
{ _^;;i4VZ  
nStartPos = input.readLong(); Ex,JB +  
nEndPos = input.readLong(); O_CT+Ou  
} x}"Q8kD  
input.close(); ##~!M(c  
} LP>UU ,Z  
catch(IOException e){e.printStackTrace ();} EhXiv#CZ  
catch(Exception e){e.printStackTrace ();} w`#fH  
} nYov>x]  
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private void processErrorCode(int nErrorCode) zUQe0Gc.b^  
{ qz:]-A  
System.err.println("Error Code : " + nErrorCode); A[9NP-~  
} a;&}zcc*  
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//停止文件下载 + zDc  
public void siteStop() 6$z'wy/*  
{ X8b#[40:  
bStop = true; {bTeAfbf]  
for(int i=0;i<nStartPos.length;i++) n#>5?W  
fileSplitterFetch.splitterStop(); ;C_ >  
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} p"KV*D9b  
} /| f[us-w  
//负责部分文件的抓取 uo 4xnzc  
**FileSplitterFetch.java "UpOY  
*/ ]^!}*  
package NetFox; U?EG6t  
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import java.io.*; ?360SQ<  
import java.net.*; N?^_=KE@  
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public class FileSplitterFetch extends Thread { ++k J\N{  
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String sURL; //File URL paYz[Xq  
long nStartPos; //File Snippet Start Position ^?sSx!:bZ  
long nEndPos; //File Snippet End Position V g6S/-  
int nThreadID; //Thread's ID ]Da4.s*mW  
boolean bDownOver = false; //Downing is over +U=KXv  
boolean bStop = false; //Stop identical dgY5ccP  
FileAccessI fileAccessI = null; //File Access interface ecT]p  
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}#|2z}!  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException [k~C+FI  
{ P,`=]Y*  
this.sURL = sURL; .)0gz!Z  
this.nStartPos = nStart; e#m1X6$.e  
this.nEndPos = nEnd; `OLB';D  
nThreadID = id; ?Hk.|5A}  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 D9G0k[D,  
} wNR=?Z~  
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public void run() 5E.vje{U
;  
{ U5clQiow  
while(nStartPos < nEndPos && !bStop) No~6s.H  
{ =ty2_6&>  
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try{ _]_LF[  
URL url = new URL(sURL); 'Dq"e$JM<  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); O E]~@eU  
httpConnection.setRequestProperty("User-Agent","NetFox"); ME,duY/>Q  
String sProperty = "bytes="+nStartPos+"-"; 8ur_/h7  
httpConnection.setRequestProperty("RANGE",sProperty); r.Lx%LZ\^  
Utility.log(sProperty); 3m~U(yho  

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InputStream input = httpConnection.getInputStream(); lkyJ;}_**  
//logResponseHead(httpConnection); "|\94  
3} l;  
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byte[] b = new byte[1024]; [@zkv)D6  
int nRead; )Jmw|B  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 8vu2k>  
{ |:}L<9Sq  
nStartPos += fileAccessI.write(b,0,nRead); eNivlJ,K|@  
//if(nThreadID == 1) }:"R-s  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ELD +:b  
} /T{mS7EpYc  
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Utility.log("Thread " + nThreadID + " is over!"); w zdxw$E  
bDownOver = true; z^"?sd  
//nPos = fileAccessI.write (b,0,nRead); $/os{tzjd  
} &9k"9  
catch(Exception e){e.printStackTrace ();} i /C'0  
}
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} B piEAwh  
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//打印回应的头信息 rC~_:uXtE  
public void logResponseHead(HttpURLConnection con) "_Zh5 g  
{ mJ/^BT]  
for(int i=1;;i++) QK,=5~IJ  
{ C?bXrG\  
String header=con.getHeaderFieldKey(i); -<_+-t  
if(header!=null) Cnk#Ioz  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); '\4c "Ho  
Utility.log(header+" : "+con.getHeaderField(header)); n2H&t>N  
else t% <pbZO  
break; 5BZ+b_A>VV  
} _8Pmv$   
} yFIl^Ck%  
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public void splitterStop() 9{T 8M  
{ e3G7K8  
bStop = true; u87=q^$  
} rGGS]^  
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} T<!\B]  
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/* Q=dw 6  
**FileAccess.java oA5<[&~<  
*//文件访问(定位，写) -wJ  
package NetFox; ccIDMJ=2
 
import java.io.*; 8|fLe\"  
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public class FileAccessI implements Serializable{ ,M| QN*  
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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 GP0[Y  
RandomAccessFile oSavedFile; <.y;&a o  
long nPos; # w i&n  
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public FileAccessI() throws IOException )*"T  
{ Vf@S8H  
this("",0); mYzsTUq  
} oUnq"]  
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public FileAccessI(String sName,long nPos) throws IOException uZo]8mV  
{ U&tfl/  
oSavedFile = new RandomAccessFile(sName,"rw"); _Ac/ir[,:  
this.nPos = nPos; WK/b=p|#o  
oSavedFile.seek(nPos); 7*R{u*/e  
} //ne']L  
^Tb}]aHg  
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public synchronized int write(byte[] b,int nStart,int nLen) =ip~J<sw&  
{ yBUZVqqDa  
int n = -1; r@N39O*Wq  
try{ LG"BfYy6  
oSavedFile.write(b,nStart,nLen); ,AGM?&A  
n = nLen; WsG"x>1n  
} 7-g]A2N  
catch(IOException e) $%N;d>[U,  
{ 3sd{AkD^  
e.printStackTrace (); P2A]qX  
} ;$E~ZT4p  
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return n; ^K1~eb*K  
} 3:l:~Vn  
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} w!=_  
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/* bn^mL~  
**SiteInfoBean.java -N /8Ho  
*/ 60
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package NetFox; [qO5~E`;  
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public class SiteInfoBean { (1saof*p%  
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private String sSiteURL; //Site's URL KNO*)\
  
private String sFilePath; //Saved File's Path L@d]RMNv  
private String sFileName; //Saved File's Name \UkNE5  
private int nSplitter; //Count of Splited Downloading File bv:0EdVr  
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46
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public SiteInfoBean() >uP{9kDm  
{//nSplitter的缺省值为5 H`+]dXLB  
//default value of nSplitter is 5 y4)ZUv,}  
this("","","",5); ArEH%e  
} IxK 3,@d  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) }5fI*v  
{ "W,"qFx  
sSiteURL= sURL; flm,r<*}  
sFilePath = sPath; "R\\\I7u  
sFileName = sName; kcma/d  
this.nSplitter = nSpiltter; RpaA)R,  
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} y$r?t0
 
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public String getSSiteURL() zn?a|kt  
{ +i q+  
return sSiteURL; h!t2H6eyF  
} /%}YuN  
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public void setSSiteURL(String value) ;|2;kvf"w  
{ i+T0}M<  
sSiteURL = value; kHo;9j-U  
} 4%c7#AX[T  
B9;,A;E};  
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public String getSFilePath() =Y=^]ayO/  
{ 46.q anh  
return sFilePath; Jb)eC?6O  
} @]VvqCk  
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public void setSFilePath(String value) 40l#'< y;  
{ S9ak '  
sFilePath = value; 9{]r+z:  
} ay7+H7^|hZ  
d= T9mj.@  
]= QCCC  
public String getSFileName() MCWG*~f  
{ {]/Jk07  
return sFileName; J?,!1V=  
} *v7& T  
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public void setSFileName(String value) c_8mQ  
{ 2zrWR%B  
sFileName = value; Xm:gD6;9  
} Ll E_{||h  
?\p
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|@bNd7=2d  
public int getNSplitter() ~PS2[5yo  
{ Uub%s`O  
return nSplitter; |EEz>ci  
} t%YX-@  
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R;-FZ@u/  
public void setNSplitter(int nCount) BO\`m%8md  
{ s?\9i6  
nSplitter = nCount;
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} ,DUQto  
} G|Yp<W%o  
ws(}K+y_  
[F-u'h< *l  
/* ujp,D#xHP  
**Utility.java ,["|wqM  
*/ 
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package NetFox; hw.demD  
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public class Utility { k49n9EX  
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public Utility() zSv
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{ \]:NOmI^'  
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j tkPi)QR  
} Ty`=U>K|  
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//线程睡眠 i@?<]n  
public static void sleep(int nSecond) D@1
^:'$V  
{ H.G^!0j;  
try{ ia.B@u1/  
Thread.sleep(nSecond); [&}<!:9'  
} ;%.k}R%O@  
catch(Exception e) 6!PX! UkF  
{ bIl0rx[`  
e.printStackTrace (); ]]QCJf@p  
} {_N(S]Z  
} 4)Wzj4qW  
-OGy-"  
//日志 #UnO~IE.m$  
public static void log(String sMsg) zSufU2  
{ +A3\Hj&W  
System.err.println(sMsg); .8xacVyK2  
} Ox1QP2t6Y  
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lSv;wwEg  
public static void log(int sMsg) cx%9UK*c  
{ -r0\  
System.err.println(sMsg); :hdh$}y  
} y(BLin!O.  
} e$|)wOwU  
fe`G^hV  
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/* ba:^zO^  
**TestMethod.java (j Q6~1  
*/ o:\j/+]  
package NetFox; `D4'`Or-U  
XQ y|t"Vq>  
*G"#.YvE  
public class TestMethod { Y-k~ 7{7  
MM$"6Jor  
f3B8,>  
public TestMethod() 4T\/wyq0  
{ ///xx/weblogic60b2_win.exe ^u&Khc~ y  
try{ W
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7n]%`Yb  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); }ZGpd
9D  
SiteFileFetch fileFetch = new SiteFileFetch(bean); &8L\FAY0%9  
fileFetch.start(); D??/=`|8  
} Gf.o{  
catch(Exception e){e.printStackTrace ();} T1[ZrY'0  
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md LJ,w?{  
} OvG|=  
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public static void main(String[] args) LZ:\V)5+  
{ .Q@'Ob`  
new TestMethod(); ,1+_k ="Z  
} }f*S 9V  
} 1<e%)? G  
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