http断点续传简单实现（java)

/* OZB(4{vnyC  
**SiteFileFetch.java -5\hZ!!J2  
*/ CcG{+-=H)  
package NetFox; pmv;M`_|R  
import java.io.*; -1DQO|q
#  
import java.net.*; tF+m/}PM^  
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public class SiteFileFetch extends Thread { 4w<U%57  
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SiteInfoBean siteInfoBean = null; //文件信息Bean B>AmH%f/  
long[] nStartPos; //开始位置 /2Y t\=S=  
long[] nEndPos; //结束位置 " ;8H;U`  
FileSplitterFetch[] fileSplitterFetch; //子线程对象  <]2X~+v  
long nFileLength; //文件长度 F\^9=}b_i  
boolean bFirst = true; //是否第一次取文件 A9`& Wnw?  
boolean bStop = false; //停止标志 ^7G@CBi
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File tmpFile; //文件下载的临时信息 PJ5~,4H-4  
DataOutputStream output; //输出到文件的输出流 ]DHB'NOh,  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） R7+3$F5B  
public SiteFileFetch(SiteInfoBean bean) throws IOException VJ8cls<  
{ :D|"hJ  
siteInfoBean = bean; Oi+9kk e  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); VEj-%"\  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ecfw[4B`  
if(tmpFile.exists ()) yU<T_&
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{ 4! ]28[2B6  
bFirst = false; !VBl/ aU@  
read_nPos(); E4idEQ}H  
} #;4<dDVy  
else >NwS0j$j@  
{ >c %*:
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nStartPos = new long[bean.getNSplitter()]; <H03i"Z/S  
nEndPos = new long[bean.getNSplitter()]; xn|M]E1)  
} jrJ!A(<)  
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} *i3\`;^=  
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public void run() "V|&s/9  
{ jRdmQmTJ  
//获得文件长度 Esx"nex  
//分割文件 Ns ezUk8'  
//实例FileSplitterFetch CCx_
|>  
//启动FileSplitterFetch线程 jMFLd  
//等待子线程返回 lqdil l\  
try{ p6P .I8g  
if(bFirst) ]c/k%]o~  
{ Q1hHK'3w  
nFileLength = getFileSize(); AIN Fv;  
if(nFileLength == -1) FL
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{ TQhu$z<  
System.err.println("File Length is not known!"); dZMf5=tb  
} 5 1&||.  
else if(nFileLength == -2) ^/c v
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{ Hst]}g' .  
System.err.println("File is not access!");
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} :[P)t %  
else e97Ll=>  
{ g+v
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for(int i=0;i<nStartPos.length;i++) ) oypl+y  
{ J]mG!#9  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); YL[n85l>1  
} P6G&3yPt  
for(int i=0;i<nEndPos.length-1;i++) >G#SfE$0  
{ cJ^{iOQ+  
nEndPos = nStartPos[i+1]; ."X}A t  
} *h([ai"1-  
nEndPos[nEndPos.length-1] = nFileLength; p<[gzmU9\b  
} "/ 9EUbca  
} IJ[r!&PY  
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//启动子线程 v~.nP} E^  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ),!1B%  
for(int i=0;i<nStartPos.length;i++) .dwy+BzS  
{ m.6O%jD  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), f$y`tT %o  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), k.5(d.*(  
nStartPos,nEndPos,i); fex<9'e  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 5 *R{N ~>  
fileSplitterFetch.start(); dilom#2l  
}  WPu-P  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7$zeRYD+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); aTWC
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", .D8|_B  
nEndPos = " + nFileLength); -Z(='A
 
// fileSplitterFetch[nPos.length-1].start(); =tS#t+2S  
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//等待子线程结束 1-=ZIHW  
//int count = 0; gJFx#s0?6.  
//是否结束while循环 '$q=r x  
boolean breakWhile = false; >}7Ml  
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while(!bStop) `qs[a}%'>"  
{ eJ ;a}{ 4%  
write_nPos(); '_~qAx@F#c  
Utility.sleep(500); ou\M}C`E  
breakWhile = true; g15~+;33N  
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for(int i=0;i<nStartPos.length;i++) b2r]>*Vc  
{ ;R[w}#Sm  
if(!fileSplitterFetch.bDownOver) ,j!%,!n o  
{ VV+gPC  
breakWhile = false; +5i~}Q!  
break; ZJf:a}=h  
} %o  
} 5Y4#aq   
if(breakWhile) }.k*4Vw#Wt  
break; oAprM Z7Y  
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//count++; !)4'[5t"U  
//if(count>4) M* 0zvNg  
// siteStop(); Y/<`C  
} p#aB0H3  
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System.err.println("文件下载结束！"); OB4nE}NO  
} 7!g"q\s  
catch(Exception e){e.printStackTrace ();} PpLuN12H  
} ^61;0   
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 SH6+'7  
//获得文件长度 =&t]R? F  
public long getFileSize() 6PyW(i(bs  
{ Am@:<J  
int nFileLength = -1; 2DNB?,uP,'  
try{ 83!{?EPE  
URL url = new URL(siteInfoBean.getSSiteURL()); lj /IN[U/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); =Cc]ugl7-  
httpConnection.setRequestProperty("User-Agent","NetFox"); Y !%2vOt  
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int responseCode=httpConnection.getResponseCode(); %Y-5L;MI  
if(responseCode>=400) ER,!`C]  
{ ;_S DW  
processErrorCode(responseCode); 9]%2Yb8SC  
return -2; //-2 represent access is error 7{lWg x  
} NjbIt=y  
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String sHeader; zJ30ZY:  
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for(int i=1;;i++) _BoYyJQH  
{ muMd
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); dUL*~%2I  
//Utility.log(in.readLine()); _>J`e7j+  
sHeader=httpConnection.getHeaderFieldKey(i); w<u@L  
if(sHeader!=null) 39~te%;C7  
{ op($+Q  
if(sHeader.equals("Content-Length")) 22/"
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{ MZ?+I~@  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 3el/,v|qj  
break; A,EuUp  
} @

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} 2^%O%Pc  
else A=sz8?K+`  
break; Y;"jsK{$  
} \dbaY:(  
}  7LB%7~{<  
catch(IOException e){e.printStackTrace ();} :F_>`{  
catch(Exception e){e.printStackTrace ();} 0oe2X1.%  
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Utility.log(nFileLength); ;xL8W  
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return nFileLength; -jzoGzC3  
} X%5 `B2Wu  
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//保存下载信息（文件指针位置） TK0WfWch  
private void write_nPos() C`-CfZZ  
{ 2UIZ<#|D>s  
try{ X|yVRQ?F`  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Y$#6%`*#>n  
output.writeInt(nStartPos.length); SkmKf~v  
for(int i=0;i<nStartPos.length;i++) 1\)C;c
,  
{ >S8 n8U  
// output.writeLong(nPos); =b8u8*ua  
output.writeLong(fileSplitterFetch.nStartPos); 4aKppj  
output.writeLong(fileSplitterFetch.nEndPos); wD/jN:  
} s@E)=;!  
output.close(); sm{/S*3  
} E:-~SH}  
catch(IOException e){e.printStackTrace ();} OdOn wY  
catch(Exception e){e.printStackTrace ();} 96S$Y~G#&  
} q8uq%wf  
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//读取保存的下载信息（文件指针位置） ,M:[GuXD<  
private void read_nPos() E@6gTx*  
{ mmG]|Cl@  
try{ ArScJ\/Nwv  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 49
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int nCount = input.readInt(); omznSL  
nStartPos = new long[nCount]; o2;Eti  
nEndPos = new long[nCount]; `l6OQdB3W  
for(int i=0;i<nStartPos.length;i++) 138v{Z  
{ .V\~#Ro$G  
nStartPos = input.readLong(); s8 u`v1  
nEndPos = input.readLong(); lANi$ :aE  
} A-d<[@d0  
input.close(); -d thY(8  
} gvPHB+#A  
catch(IOException e){e.printStackTrace ();} }{kn/m/  
catch(Exception e){e.printStackTrace ();} p&#ju*i6z  
} Anqt:(  
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private void processErrorCode(int nErrorCode) ~*J <lln  
{ &gW<v\6,  
System.err.println("Error Code : " + nErrorCode); mY[*Cj3WJ  
} !&cfX/y8  
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//停止文件下载 )T?BO  
public void siteStop() -0BxZ AW=  
{ 9P,[MZ  
bStop = true; &/:c?F?l  
for(int i=0;i<nStartPos.length;i++) LpI4R  
fileSplitterFetch.splitterStop(); ,izp^,`  
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} 6 8fnh'I!  
} ic3Szd^4  
//负责部分文件的抓取 _/
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**FileSplitterFetch.java 
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*/ .:
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package NetFox; Mn3j6a  
}eI9me@Aa  
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import java.io.*; MiKq|  
import java.net.*; O_GHvLO=  
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public class FileSplitterFetch extends Thread { Nf2lw]-G4  
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String sURL; //File URL YXmy-o>  
long nStartPos; //File Snippet Start Position osmCwM4O  
long nEndPos; //File Snippet End Position T00sYoK  
int nThreadID; //Thread's ID n5efHJU  
boolean bDownOver = false; //Downing is over qsN_EMgbdn  
boolean bStop = false; //Stop identical ydRS\l  
FileAccessI fileAccessI = null; //File Access interface pIug$Ke_%  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException "vkM*HP  
{ ;%i-:<ac  
this.sURL = sURL; aqI
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this.nStartPos = nStart; ^^24a_+2  
this.nEndPos = nEnd; LaZ @4/z!  
nThreadID = id; p%X.$0  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 =h?%<2t9<  
} bE=[P}E  
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public void run() D8xE"6T>  
{ {j<?+o5A  
while(nStartPos < nEndPos && !bStop) YguW2R=6]  
{ a@9W'/?igk  
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try{ Yt_t>  
URL url = new URL(sURL); @Jlsx0i}}  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); KV'3\`v@LY  
httpConnection.setRequestProperty("User-Agent","NetFox"); E0aFHC[  
String sProperty = "bytes="+nStartPos+"-"; c=a;<,Rzb  
httpConnection.setRequestProperty("RANGE",sProperty); /}%C'  
Utility.log(sProperty); -]YsiE?r  
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InputStream input = httpConnection.getInputStream(); n$>_2v  
//logResponseHead(httpConnection); vfVF^ WOd  
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byte[] b = new byte[1024]; F4~O-g.<  
int nRead; LW/> %  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) mZ3Z8q}%P  
{ f{\[+>  
nStartPos += fileAccessI.write(b,0,nRead); ^L\w"`,~  
//if(nThreadID == 1) .#K\u![@N  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); An,TunX  
} %RzkP}1>E  
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Utility.log("Thread " + nThreadID + " is over!"); goD#2
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bDownOver = true; /nt%VLms%  
//nPos = fileAccessI.write (b,0,nRead); &4M,)Q (  
} UD5
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catch(Exception e){e.printStackTrace ();} NjdDImz.;s  
} $z5C+K@  
} O\@0o|NM  
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//打印回应的头信息 YPw=iF]  
public void logResponseHead(HttpURLConnection con)  xG'F  
{ u2U+uD@yA  
for(int i=1;;i++) S6_dmTV*  
{ :0o]#7  
String header=con.getHeaderFieldKey(i); 5fp&!HnG  
if(header!=null) -.Z;n1'^  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); "9y0]~  
Utility.log(header+" : "+con.getHeaderField(header)); !P
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else @ "CP@^  
break; g\aq#QV  
} xR&Le/3+  
} 'm/`= QX  
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public void splitterStop() d#I; e  
{ 9; aOUs:<  
bStop = true; 8ROZ]Xh,x  
} UGA``;f  
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} irGgo-x  
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/* "?"+1S  
**FileAccess.java |W|RX3D  
*//文件访问(定位，写) Z. xOO|  
package NetFox; 3rx8"  
import java.io.*; Cs^'g'  
j$z!kd+%  
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public class FileAccessI implements Serializable{ xJ\>;$CY  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 C4eQ.ep  
RandomAccessFile oSavedFile; [-3x*?Ju  
long nPos; Tpp?(lT7r  
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public FileAccessI() throws IOException oJ0ZZu?{D  
{ @t3&#I}mc  
this("",0); zj#8@gbh+  
} wf,w%n  
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public FileAccessI(String sName,long nPos) throws IOException PW"uPn  
{ j\uPOn8k  
oSavedFile = new RandomAccessFile(sName,"rw"); oP`Qyk  
this.nPos = nPos; u 9kh@0  
oSavedFile.seek(nPos); vC-5_pl  
} l9F]Lw  
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public synchronized int write(byte[] b,int nStart,int nLen) |SwW*C  
{ kaNK@a=e|/  
int n = -1; mP-Y9*k  
try{ ^ZDpG2(zk  
oSavedFile.write(b,nStart,nLen); M}N[> ,2'  
n = nLen;  *#sY-Gd  
} G`FY[^:  
catch(IOException e) Q>l5:2lq  
{ 2NZC,znQ  
e.printStackTrace (); ITBa ^P  
} 80Z'1'u0  
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return n; ECLQqjB  
} xtX`3=s  
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} rHD_sC*  
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/* a>BPK"K2  
**SiteInfoBean.java 75*q^ui  
*/ U$=#yg2 :  
package NetFox; 
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public class SiteInfoBean { L IRdWGQ4  
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private String sSiteURL; //Site's URL >\ x!a:}  
private String sFilePath; //Saved File's Path R}HNi(%"  
private String sFileName; //Saved File's Name roHJ$~q?  
private int nSplitter; //Count of Splited Downloading File G^qt@,n$;  
+`l)W`zX  
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public SiteInfoBean() whh#J (  
{//nSplitter的缺省值为5 d3tr9B  
//default value of nSplitter is 5 zL/rV<  
this("","","",5); y.Y;<UGu  
} G)3Q|Vc  
9UE)4*5  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 2su/I  
{ ?[c{pb,|  
sSiteURL= sURL; !]t5(g_  
sFilePath = sPath; Q ?R3aJ  
sFileName = sName; 9y{R_  
this.nSplitter = nSpiltter; '0 J*9  
NM0s*s42  
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} H_d^Xk QZ  
<7Ry"z6g;  
)h`8</#m{  
public String getSSiteURL() PHxNo)  
{ b&2N7%  
return sSiteURL; %ZM"c  
} [K""6D  
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public void setSSiteURL(String value) LW!>_~g-  
{ a9g~(#?a  
sSiteURL = value; k\KI#.>  
} XS=f>e1<W  
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public String getSFilePath() =+w!fy  
{ $nr=4'yZ  
return sFilePath; aI_[h v  
} _t?#
 
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public void setSFilePath(String value) <HH\VG\H6  
{ 7\[)5j  
sFilePath = value; l-$5CO  
} *>E_lWW.  
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*=X61`0  
public String getSFileName() c'SjH".[  
{ 1 RVs!;  
return sFileName; 6o&ZS @  
} Q$b4\n?44  
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public void setSFileName(String value) $g_|U:,  
{ m2[]`Ir^@  
sFileName = value; 0( q:K6zI}  
} Egmp8:nZl@  
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public int getNSplitter() :QIf0*.O  
{ &Gs/#2XQ  
return nSplitter; Cs2kbG_  
} 7n]ukqZ  
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public void setNSplitter(int nCount) Hi nJ}MF  
{ Zi{vEI]  
nSplitter = nCount; jHk.]4&0  
} >dXB)yl  
} ~d-Q3n?
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/* MavidkS  
**Utility.java AjJ/t4<  
*/ b9VI(s>  
package NetFox; j\iNag(  
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public class Utility { .|0$?w  
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public Utility() U/ax`_  
{ ]e$n;tuW  
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} 4U3 `g  
3gYtu-1  
//线程睡眠 MAQ-'s@  
public static void sleep(int nSecond) J^!wk
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{ 'p)DJUwt  
try{ .  LeS-  
Thread.sleep(nSecond); W9]0X  
} qp{~OW3  
catch(Exception e) O"1HO[  
{ oJ|m/i)  
e.printStackTrace (); w$j6!z  
} t ?05  
} r{f
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&~'i,v|E  
//日志 `Om W#\  
public static void log(String sMsg) #mD_<@@  
{ 0^)~p{Zh  
System.err.println(sMsg); OS1f}<  
} u+c2 m  
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public static void log(int sMsg) I8|"h8\  
{ JW"`i   
System.err.println(sMsg); )1 QOA  
} 3Kq/V_  
} /N,\st  
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/* (B%[NC6  
**TestMethod.java qpzyl~g:C  
*/ J&B5Ll  
package NetFox; 3QF[@8EH{  
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2*] [M,L0c  
public class TestMethod { yCkX+{ki  
7~;)N$d\  
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public TestMethod() x:h)\%Dg<  
{ ///xx/weblogic60b2_win.exe CWJ
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try{ cucT|y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); =5:S"WNj  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 1 |/ |Lq%w  
SiteFileFetch fileFetch = new SiteFileFetch(bean); mHa~c(x  
fileFetch.start(); ab#z&jg!  
} EVE"F'Ww,_  
catch(Exception e){e.printStackTrace ();} I!Mkss xc  
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} p*Yx1er1  
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public static void main(String[] args) lkC|g
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{ \HQ.Pwr 6  
new TestMethod(); -BWWaL  
} =NSunW!  
} _;:_ !`
 
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