http断点续传简单实现（java)

/* R['k&jyi  
**SiteFileFetch.java Y%1J[W  
*/ e7fA-,DV  
package NetFox; Sw<V/t  
import java.io.*; s*blZdP  
import java.net.*; HkgmZw,  
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public class SiteFileFetch extends Thread { 7hQf T76h  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Woo2hg-ti  
long[] nStartPos; //开始位置 Z33&FUU  
long[] nEndPos; //结束位置 7.G1Q]6/  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 f{]eb1  
long nFileLength; //文件长度 GoVB
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boolean bFirst = true; //是否第一次取文件 G'*_7HD  
boolean bStop = false; //停止标志 zP[_ccW@  
File tmpFile; //文件下载的临时信息 [8T  
DataOutputStream output; //输出到文件的输出流 fa~u<m  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） eh@6trzp=  
public SiteFileFetch(SiteInfoBean bean) throws IOException b7X-mkF  
{ YJioR4+q  
siteInfoBean = bean; Yn0l}=, n  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); q;Y9_5S  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Cpyv@+;D  
if(tmpFile.exists ()) hJ)>BeH0  
{ HLjXH#ry  
bFirst = false; W6kDQ&q  
read_nPos(); #Kr\"o1]  
} :j
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else F4=+xd >0  
{ < C{-ph  
nStartPos = new long[bean.getNSplitter()]; MT`gCvoF4P  
nEndPos = new long[bean.getNSplitter()]; a,B2;4"  
} )+
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} O{0TS^  
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public void run() gH{X?  
{ +3@d]JfMh  
//获得文件长度 yQ^k%hHa  
//分割文件 I=N;F6  
//实例FileSplitterFetch bu;3Ib3\  
//启动FileSplitterFetch线程 ,&wTUS\  
//等待子线程返回 D][e u
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try{ %SWtE5HZQq  
if(bFirst) Mn<G9KR  
{ y;0k |C
 
nFileLength = getFileSize(); 'Gn-8r+  
if(nFileLength == -1) .d\<}\zZ7J  
{ GrwoV~  
System.err.println("File Length is not known!"); buIy+  
} [G(}`u8w"  
else if(nFileLength == -2) s_`PPl_D$K  
{ mLa0BIP  
System.err.println("File is not access!"); &e#>%0aS  
} 8 *Fr=+KN  
else @,b:s+]rp  
{ bzz{ p1e  
for(int i=0;i<nStartPos.length;i++) -EwtO4vLJ  
{ Fx^e%":@ip  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); /F>\-    
} x~7_`=}rO  
for(int i=0;i<nEndPos.length-1;i++) >DHpD?Pm!  
{ aJnZco6  
nEndPos = nStartPos[i+1]; Z*/*P4\  
} f87>ul!*  
nEndPos[nEndPos.length-1] = nFileLength; 'rT@r:6fn  
} c*O{?b  
} c1v,5c6d j  
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//启动子线程 vV2px  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; aFI?^"L  
for(int i=0;i<nStartPos.length;i++) ,bv?c@  
{ nm[ yp3B  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ##%R|P3  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), R]oi&"H@r)  
nStartPos,nEndPos,i); "82<}D^;  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); P#
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fileSplitterFetch.start(); B
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} Tk9/1C{8  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), M4;A4V=W  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ^7l.!s#$b  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", [+=h[DC  
nEndPos = " + nFileLength); V;b^b5yZ>  
// fileSplitterFetch[nPos.length-1].start(); _g%Wx?K9  
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//等待子线程结束 A+JM* eB  
//int count = 0; p[Z'Fl  
//是否结束while循环 QlbhQkn  
boolean breakWhile = false; Y,v8eOo45S  
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while(!bStop) }m?1IU%q  
{ tDuQ+|~M  
write_nPos(); OG#7Va  
Utility.sleep(500); [zO
   
breakWhile = true; "}uPz4  
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for(int i=0;i<nStartPos.length;i++) YF{KSGq  
{ 4<`x*8` ,  
if(!fileSplitterFetch.bDownOver) fo"dX4%}  
{ u9AXiv+K  
breakWhile = false; R5QSf+/T4  
break; "s']@Qv  
} u8Ul +u  
} gnS0$kCJ:  
if(breakWhile) &} b'cO  
break; !_+LmBd G  
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//count++;  (-
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//if(count>4) {u BpM9KT  
// siteStop(); >
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} #;F1+s<|QJ  
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System.err.println("文件下载结束！"); RH,(8.&>r  
} urT!?*g,  
catch(Exception e){e.printStackTrace ();} Q+ ;6\.#r  
} >@b70X!J]  
&[BDqi  
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//获得文件长度 !<"H73?fl  
public long getFileSize() P |c6V  
{ A[lkGQtS4  
int nFileLength = -1; .tB[8Y=J  
try{ dZ UB  
URL url = new URL(siteInfoBean.getSSiteURL()); w.qpV]9>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); aHKv*-z-  
httpConnection.setRequestProperty("User-Agent","NetFox"); B\2<r5|QG  
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+ M2|-C  
int responseCode=httpConnection.getResponseCode(); tzv&E0|d  
if(responseCode>=400) )W&H{2No  
{ f=v+D0K$n  
processErrorCode(responseCode); MVV9[f  
return -2; //-2 represent access is error N|eus3\E  
} .M_[tl  
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String sHeader; 3=!\>0;E-  
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for(int i=1;;i++) zJWh  
{ (o_wv  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); wVCZ=\L}  
//Utility.log(in.readLine()); PTe8,
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sHeader=httpConnection.getHeaderFieldKey(i); &?(
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if(sHeader!=null) YPAMf&jEF  
{ >
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if(sHeader.equals("Content-Length")) %WrUu|xj>_  
{ uX@RdkC  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); h?2qX  
break; _yTGv-  
} ' }rUbJo  
} 8D eRs#  
else e:IUO1#  
break; =
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} 6\(wU?m'/  
} xW*L^97 ;  
catch(IOException e){e.printStackTrace ();} MyZ@I7Fb,  
catch(Exception e){e.printStackTrace ();} ZbJzf]y:6  
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Utility.log(nFileLength); U/E M(y  
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return nFileLength; nG&=$7x^  
} EzK,SN#  
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//保存下载信息（文件指针位置） }6}Gj8Nb  
private void write_nPos() ~;W]0d4,\  
{
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try{ y5>859"h  
output = new DataOutputStream(new FileOutputStream(tmpFile)); U3MfEM!x  
output.writeInt(nStartPos.length); :
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for(int i=0;i<nStartPos.length;i++) ny17(Y =  
{ xd\k;nq  
// output.writeLong(nPos); W[A;VOj0$  
output.writeLong(fileSplitterFetch.nStartPos); fB[I1Z  
output.writeLong(fileSplitterFetch.nEndPos); vINm2%*zJ  
} M(o?I}  
output.close(); l)`bm/k]V  
} y4s]*?Wz  
catch(IOException e){e.printStackTrace ();} ~a&s5E {  
catch(Exception e){e.printStackTrace ();} ]O s!=rt  
} ),5^bl/  
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//读取保存的下载信息（文件指针位置） %..{c#V  
private void read_nPos() LBT
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{ R[5*]$(b  
try{ <jXXj[M2  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); # )-Kf  
int nCount = input.readInt(); tG(?PmQ  
nStartPos = new long[nCount]; m\|I.BUG  
nEndPos = new long[nCount]; JnH>L|G{;%  
for(int i=0;i<nStartPos.length;i++) 1Qui.],c  
{ ~p<o":k+Lv  
nStartPos = input.readLong(); UOH2I+@V  
nEndPos = input.readLong(); tsR\cO~/  
} F>E'/r*  
input.close(); y/rmxQtP  
} 1pogk0h.:  
catch(IOException e){e.printStackTrace ();} N~g@  
catch(Exception e){e.printStackTrace ();} t8 g^W K  
} hv te)  
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private void processErrorCode(int nErrorCode) `s(T(l  
{ ZWaHG_ U)  
System.err.println("Error Code : " + nErrorCode); .)|r!X  
} =Y>_b 2  
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//停止文件下载 oe,L&2Jz@  
public void siteStop() Ej>5PXp'2  
{ l'HrU 1_7Y  
bStop = true; gJ cf~@s  
for(int i=0;i<nStartPos.length;i++) }5-^:}gL
 
fileSplitterFetch.splitterStop(); 74ma   
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} xM}lX(V!w  
} vs;T}'O  
//负责部分文件的抓取 (D F{l?4x-  
**FileSplitterFetch.java Fp..Sjh 6  
*/ q:@$$}FjL  
package NetFox; %k @"*  
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import java.io.*; dQLR%i#P8  
import java.net.*; XzGPBi  
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public class FileSplitterFetch extends Thread { 8?!=/Sc  
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String sURL; //File URL bS_fWD-  
long nStartPos; //File Snippet Start Position p6u"$)wt  
long nEndPos; //File Snippet End Position Tq[=&J  
int nThreadID; //Thread's ID w
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boolean bDownOver = false; //Downing is over %4
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boolean bStop = false; //Stop identical `!Ei H<H}  
FileAccessI fileAccessI = null; //File Access interface pJ-/"Q|:i  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException &(3kwdI  
{ }6b=2Z}  
this.sURL = sURL; ;*ebq'D([  
this.nStartPos = nStart; U,S&"`a  
this.nEndPos = nEnd; :{?8rA5  
nThreadID = id; cN_e0;*Ua  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 \xJTsdd  
} &*iar+vr  
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public void run() R}7>*&S:  
{ 289teU  
while(nStartPos < nEndPos && !bStop) n.P$7%G`2  
{ {t`UV,  
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try{ &niROM,;K  
URL url = new URL(sURL); 7c$;-O  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); v[WbQ5AND  
httpConnection.setRequestProperty("User-Agent","NetFox"); a}eM ny  
String sProperty = "bytes="+nStartPos+"-"; 6U)Lhf\'o  
httpConnection.setRequestProperty("RANGE",sProperty); "MZj}}l  
Utility.log(sProperty); ;Q>(%"z};  
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InputStream input = httpConnection.getInputStream(); 1^rODfY0  
//logResponseHead(httpConnection); .PBma/w W  
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byte[] b = new byte[1024]; u!`oKe;  
int nRead; %cJ]Ds%V  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) @q2If{Tk  
{ ]>-#T  
nStartPos += fileAccessI.write(b,0,nRead); %tiFx:F+  
//if(nThreadID == 1) HI6;=~[  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Q|Uq.UjY  
} Q| > \{M  
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Utility.log("Thread " + nThreadID + " is over!"); {<%zcNKl^L  
bDownOver = true; i)=!U>B_0  
//nPos = fileAccessI.write (b,0,nRead); >J>4g;Y  
} fdP[{.$?(  
catch(Exception e){e.printStackTrace ();} YOo?.[}@  
} !Ziq^o.  
} 'V
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//打印回应的头信息 (5Q,d [B  
public void logResponseHead(HttpURLConnection con) |mvy@
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{ Q)x`'[3"7W  
for(int i=1;;i++) /Y|oDfv  
{ TUzpln  
String header=con.getHeaderFieldKey(i); vy\;#X!  
if(header!=null) ?h4-D:!$L  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); vQCRs!A  
Utility.log(header+" : "+con.getHeaderField(header)); F3[3~r  
else PW)XDo7  
break; vhiP8DQ  
} l9 RjxO.~U  
} Z=`\U?,  
}wzU<(Rx  
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public void splitterStop() ~L j[xP  
{ A7@5lHMF  
bStop = true; c`I`@Bed  
} 3Tv;<hF  

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} ilL] pU
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/* 9Cbf[\J!bq  
**FileAccess.java aLapb5VV  
*//文件访问(定位，写) l%]S7|PKx  
package NetFox; %Z?2.)  
import java.io.*; zM?JLNs]<{  
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public class FileAccessI implements Serializable{ WMfu5x7e4  
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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 FaO1?.  
RandomAccessFile oSavedFile; f6n'g:&.W  
long nPos; IKSe X  
e-vL!&;2  
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public FileAccessI() throws IOException gd3~R+Kd  
{ `ro~l_U;A  
this("",0); ~ldqg2c  
} xv;'27mUt  
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public FileAccessI(String sName,long nPos) throws IOException ]F kLtq  
{ Ym IVtQ  
oSavedFile = new RandomAccessFile(sName,"rw"); XUeBK/aQ{  
this.nPos = nPos; 3D>syf  
oSavedFile.seek(nPos); apQ` l^  
} 7A@GNA  
0X =Yly*m@  
& xOEp  
public synchronized int write(byte[] b,int nStart,int nLen) GQ~wx1jj1  
{ $OU,| D  
int n = -1; td{M%D,R"  
try{  9')  
oSavedFile.write(b,nStart,nLen); :X7"fX  
n = nLen; lN"%~n
?  
}  )z#  
catch(IOException e) qTFktJZw  
{ 3>%oGbo  
e.printStackTrace (); 4kZX$ct}  
} Z^w11}  
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return n; #M$Gj>E%4  
} /
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} ab4(?-'-  
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/* 1j7^2Y|UT`  
**SiteInfoBean.java 7u/_3x1  
*/ QfjgBJo%  
package NetFox; -m*
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public class SiteInfoBean { ?g*#ld()  
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s"5f5Cn/Wh  
private String sSiteURL; //Site's URL y7J2:/@[x  
private String sFilePath; //Saved File's Path Dj!
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private String sFileName; //Saved File's Name ;w,+x 7  
private int nSplitter; //Count of Splited Downloading File 8nn%wps  
.*+?]  
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public SiteInfoBean() p&'oJy.P  
{//nSplitter的缺省值为5 e@[9WnxYe  
//default value of nSplitter is 5 &qfnCM0Y  
this("","","",5); *3 .+19Q  
} (
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) FJ]BB4 K  
{ D=*3Xd  
sSiteURL= sURL; /~`4a
  
sFilePath = sPath; [7d>c  
sFileName = sName; ,m<t/@^]  
this.nSplitter = nSpiltter; yhF{ cK=  
yu8xTh$:  
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} !ER,o_T<  
!Yuu~|  
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public String getSSiteURL() (6##\}L&9  
{ :H/CiN  
return sSiteURL; daamP$h9  
} #gjhs"$
~  
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public void setSSiteURL(String value) Jv*[@ -.k  
{ rGjP|v@3^  
sSiteURL = value; iDp'M`(6h  
} ,S.<qmf  
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#
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public String getSFilePath() WDznhMo  
{ t[>y=89
 
return sFilePath; 1+`Bli]dE  
} fZM)>  
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public void setSFilePath(String value) <Z^P8nu  
{ [,;h1m ~iX  
sFilePath = value; fB.xjp?  
} ~zdHJ8tYp  
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public String getSFileName() %"#%/>U4  
{ 5\hJ&  
return sFileName; JIeKp7;^  
} >,JLYz|</  
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7S"W7O1>  
public void setSFileName(String value)
/W4F(3oM  
{ &OpGcbf1  
sFileName = value; Ur^~fW1o  
} cb ICO  
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public int getNSplitter() GTvp)^h  
{ ]`[r=cG  
return nSplitter; RZwjc<T  
} $:|z{p  
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public void setNSplitter(int nCount) y_aKW4L+  
{ gWlv;oq  
nSplitter = nCount; NI(fJ%U  
} 'FVh/};Y.D  
} ^.']-XjC  
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/* G-5wv  
**Utility.java EvA{@g4>  
*/ \SA"DT  
package NetFox; ,{4G@:Fm  

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public class Utility { :z=C   
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public Utility() R~9\mi5^UH  
{ {z":hmt  
N =k}"2_=  
&hciv\YT2W  
} j2oHwt6"  
3Zy$NsY3  
//线程睡眠 D%PrwfR  
public static void sleep(int nSecond) sY @S  
{ ohI>\  
try{ V1aWVLltj  
Thread.sleep(nSecond); TDvUiJm  
} 41\r7 BS  
catch(Exception e) j/I^\Ms  
{ *hJ&7w ~  
e.printStackTrace (); l`#XB:#U  
} z:Sr@!DZ  
} %cy]dEL7  
b{:
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//日志 z:m`  
public static void log(String sMsg) UkO
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{ f-Yp`lnn.d  
System.err.println(sMsg); OyU[(  
} BU\P5uB!V  
%by8i1
HR  
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public static void log(int sMsg) {Ac5(li_  
{ @fDWp/  
System.err.println(sMsg); ZS\jbii8  
} K YSyz)M}  
} :?!kZD!  
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tS$^k)ZXip  
/* O\=U'6@  
**TestMethod.java <<xUh|zE  
*/ E=Z;T  
package NetFox; J;?#Zt]`L  
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[&6VI?  
public class TestMethod { *}yOL [  
:n1^Xw0q  
SONv]));  
public TestMethod() \ C^fi}/]  
{ ///xx/weblogic60b2_win.exe n|G x29E  
try{ fc}G6P;3{  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); -ahSFBZlg  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); C26vH#C  
SiteFileFetch fileFetch = new SiteFileFetch(bean); NGA8JV/U  
fileFetch.start(); O26'|w@$  
} ]_8bX}_n  
catch(Exception e){e.printStackTrace ();} &&(^;+  
v]"W.<B,  
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} m@|0iDS  
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public static void main(String[] args) )qgcz<p?W  
{ ^qn,b/>L  
new TestMethod(); iL^bf*  
} J>H$4t#HX  
} i{#5=np H  
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