http断点续传简单实现（java)

/* w~9=6|_  
**SiteFileFetch.java cm7>%g(oQo  
*/ ?#;zB  
package NetFox; @)wNINvD  
import java.io.*; ~{O@tt)F  
import java.net.*; =gr3a,2  
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public class SiteFileFetch extends Thread { Vt,"5c  
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SiteInfoBean siteInfoBean = null; //文件信息Bean (hX}O>  
long[] nStartPos; //开始位置 & 5YI!; q,  
long[] nEndPos; //结束位置 xSHeP`P^X  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 '||),>~  
long nFileLength; //文件长度 AJH-V 6  
boolean bFirst = true; //是否第一次取文件 jG3i )ALx  
boolean bStop = false; //停止标志 Q|}Pc>ae  
File tmpFile; //文件下载的临时信息 AU +2'  
DataOutputStream output; //输出到文件的输出流 s8N\cOd#i  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） f9 b=Zm'  
public SiteFileFetch(SiteInfoBean bean) throws IOException m)9qO7P  
{ 2L_ts=  
siteInfoBean = bean; bMw)>4  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); lTv_%hUp  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); !M&B=vk4  
if(tmpFile.exists ()) G(~"Zt}?  
{ (yel  
bFirst = false; M e  
read_nPos(); U8KEg)Msk  
} f)+fdc  
else L$+ap~ld  
{ SW%d'1ya  
nStartPos = new long[bean.getNSplitter()]; VXAgp6  
nEndPos = new long[bean.getNSplitter()]; zZ=.riK  
} :xT=uE.I  
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} ^*]0quu=z  
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public void run() 8V(#S:G35  
{ Q04iuhDO:  
//获得文件长度 x+9aTsZ  
//分割文件 GxGZxf*(  
//实例FileSplitterFetch %h%^i   
//启动FileSplitterFetch线程 s^$zOp9  
//等待子线程返回 lLT;V2=osX  
try{ xCV3HnZ  
if(bFirst) =ITMAC\  
{ <zK9J?ZQW>  
nFileLength = getFileSize(); ,9f$an  
if(nFileLength == -1) B/Lx,

 
{ q<b;xx  
System.err.println("File Length is not known!"); (k..ll p~  
} J,E'F!{  
else if(nFileLength == -2) h^5'i}@u  
{ Ui
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System.err.println("File is not access!"); "rr,P0lgX  
} |!)3[<.  
else g9;}?h  
{ }_L@CpG  
for(int i=0;i<nStartPos.length;i++) v:<UbuJw  
{ KPUc+`cN%  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); &k?Mt#J  
} <c{RY.1[  
for(int i=0;i<nEndPos.length-1;i++) -_ [Z5%B  
{ #$Z|)i]w  
nEndPos = nStartPos[i+1]; 94F9f^ L  
} wYS,|=y  
nEndPos[nEndPos.length-1] = nFileLength; QO)Q%K,  
} 16YJQ ue  
} Ov)rsi
 
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vF;%#P  
//启动子线程 ;ePmN|rq;  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; *"Ipu"G5?  
for(int i=0;i<nStartPos.length;i++) dQt*/]{q  
{ LRv-q{jP;  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), XH0R:+s  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ?/~7\ '|Z  
nStartPos,nEndPos,i); xU^Flw,4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); uM0z%z5b  
fileSplitterFetch.start(); F[c;iM(^  
} n}yqpW!%n  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), q"A(l  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ;#!`cgAh  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", lFD$Mc  
nEndPos = " + nFileLength); ~'HwNzDQc  
// fileSplitterFetch[nPos.length-1].start(); Ajhrsa\~a  
!+T+BFw.  
%?C{0(Z{  
//等待子线程结束 gRKmfJ*u  
//int count = 0; +MeEy{;  
//是否结束while循环 pscCXk(|A`  
boolean breakWhile = false; 0%+TU4Xx  
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<vA^%D<\~  
while(!bStop) Y=4,d4uu  
{ }$;T.[ ~  
write_nPos(); l9q ygh  
Utility.sleep(500); e4ajT  
breakWhile = true; "S^;X @#v  
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for(int i=0;i<nStartPos.length;i++) d;(L@9HHD  
{ Ni{(=&*=  
if(!fileSplitterFetch.bDownOver) /H,!7!6>?  
{ j+J)S1  
breakWhile = false; a)[XJLCQ  
break; EZc!QrY  
} p/'C v  
} w=3@IW  
if(breakWhile) zie])_8|h  
break; DCmNxN  
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*
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//count++; !/['wv@  
//if(count>4) M\8FjJ>9  
// siteStop(); 3`k1  
} ho@f}4jhQ3  
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System.err.println("文件下载结束！"); GOa
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} 2anx]QV4  
catch(Exception e){e.printStackTrace ();} V4 Pf?g  
} ((Ec:(:c  
F1)Q#ThF\  
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//获得文件长度 Hv<%_t_/  
public long getFileSize() aM3%Mx?w  
{ f| 3`8JU  
int nFileLength = -1;
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try{ VE6T&fz`  
URL url = new URL(siteInfoBean.getSSiteURL()); yK0Q,   
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #v')iR"  
httpConnection.setRequestProperty("User-Agent","NetFox"); X c,UR.  
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int responseCode=httpConnection.getResponseCode(); [FC7+ Ey^  
if(responseCode>=400) 7|T5N[3?l,  
{ RoLUPy9U  
processErrorCode(responseCode); ]^&DEj{  
return -2; //-2 represent access is error {{[).o/  
} /^#k/z  
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i,S%:0c7)  
String sHeader; v(=fV/  
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for(int i=1;;i++) =q^o6{d0"  
{ W2yNEiH  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); bUAjt>+  
//Utility.log(in.readLine()); LlRvm/  
sHeader=httpConnection.getHeaderFieldKey(i); =1^Ru*G  
if(sHeader!=null) *WfOB2rU  
{ +yS"pOT  
if(sHeader.equals("Content-Length")) g;\zD_":l  
{ ^Cyx"s't  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); x7l)i!/$  
break; 2#*Bw=  
} H<%7aOwO2  
} 0[T!}F^%e  
else NV*aHci  
break; aAwnkQ$  
} :I F&W=?9  
} 1 xiq]~H  
catch(IOException e){e.printStackTrace ();} t\{q,4  
catch(Exception e){e.printStackTrace ();} GfJm&'U&  
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Utility.log(nFileLength); .pi#Z/v  
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return nFileLength; Q2^}NQO=  
} E`XUK,b  
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//保存下载信息（文件指针位置） . ~G>vVb  
private void write_nPos() h}z^NX  
{ T {(6*^g<B  
try{ w^p 'D{{  
output = new DataOutputStream(new FileOutputStream(tmpFile)); zBB4lC{q  
output.writeInt(nStartPos.length); "KW\:uc /  
for(int i=0;i<nStartPos.length;i++) QCa$<~c  
{ /%Rz`}  
// output.writeLong(nPos); g*- K!X6l  
output.writeLong(fileSplitterFetch.nStartPos); i<bFF03*S  
output.writeLong(fileSplitterFetch.nEndPos); mmTc.xh  
} &
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output.close(); TxN#3m?G  
} R7x
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catch(IOException e){e.printStackTrace ();} Si6%6rAhj  
catch(Exception e){e.printStackTrace ();} ;r^8In@6  
} 6g@j,iFy  
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//读取保存的下载信息（文件指针位置） vay_QxB5  
private void read_nPos() (IIOKx_  
{ d|j3E  
try{ 'e7<&wm ia  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 8T
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int nCount = input.readInt(); SG8|xoL  
nStartPos = new long[nCount]; ~e~4S~{  
nEndPos = new long[nCount]; D>?%p"e  
for(int i=0;i<nStartPos.length;i++) I#Iu:,OT  
{ K}`.?6O  
nStartPos = input.readLong(); kIrME:  
nEndPos = input.readLong(); qK.8^{b  
} jf*M}Q1jHE  
input.close();  7I^(vQ  
} GLnj& Ve  
catch(IOException e){e.printStackTrace ();} %Ofa
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catch(Exception e){e.printStackTrace ();} 8$OE<c?#5n  
} 22}J.'Zb  

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private void processErrorCode(int nErrorCode) ~hE"B) e  
{ tE3!;  
System.err.println("Error Code : " + nErrorCode); < I8hy$+6  
} {/XzIOO;b  
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//停止文件下载 B6MMn.  
public void siteStop() k U*
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{ 1W$@ V!  
bStop = true; 8!b#ez  
for(int i=0;i<nStartPos.length;i++) MHI0>QsI  
fileSplitterFetch.splitterStop(); mAk)9`f/  
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} EXS 1.3>  
} y''`73U"  
//负责部分文件的抓取 ;5PXPpJ  
**FileSplitterFetch.java tP"C>#LO  
*/ zK k;&y|{  
package NetFox; Iy8Ehwejd  
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import java.io.*; Jq<&`6hn  
import java.net.*; 8"N<g'Yl,  
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public class FileSplitterFetch extends Thread { qg'RD]a>R  
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String sURL; //File URL n0>#?ek12  
long nStartPos; //File Snippet Start Position &}OaiTzEmc  
long nEndPos; //File Snippet End Position )
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int nThreadID; //Thread's ID $*H_0wQc  
boolean bDownOver = false; //Downing is over pLDseEr<  
boolean bStop = false; //Stop identical ht!o_0{~  
FileAccessI fileAccessI = null; //File Access interface k9.@S  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException C6M|A3^T  
{ crz )F"  
this.sURL = sURL; VI74{='=  
this.nStartPos = nStart; aVNRhnM  
this.nEndPos = nEnd; rs]%`"&=  
nThreadID = id; g&`e2|[7  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 #[qmhU{s  
} k9~NIvnB`  
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public void run() l"f.eo0@7  
{ d2Z5HFtY  
while(nStartPos < nEndPos && !bStop) 4sP0oe[h  
{ PL@hsZty~c  
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try{ 8uP,#D<wZ  
URL url = new URL(sURL); GXr9J rs.e  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); JLT10c3  
httpConnection.setRequestProperty("User-Agent","NetFox"); #@w8wCj  
String sProperty = "bytes="+nStartPos+"-"; lr=? &>MXj  
httpConnection.setRequestProperty("RANGE",sProperty); iyB02\d  
Utility.log(sProperty); 9]c2ub7  
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InputStream input = httpConnection.getInputStream(); 5@%$M$E  
//logResponseHead(httpConnection); MT[V1I{LV  
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byte[] b = new byte[1024]; 6y)TXp  
int nRead; f7Y0L8D  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) @i'R
IL}  
{ Q})x4  
nStartPos += fileAccessI.write(b,0,nRead); b^~ keQ  
//if(nThreadID == 1) A5S9F8Q/]  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1p[C5j3  
} <4ccTl  
` .|JTm[  
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Utility.log("Thread " + nThreadID + " is over!"); ,|D_? D)U  
bDownOver = true; umaF}}-Q{  
//nPos = fileAccessI.write (b,0,nRead); Dq/_^a/1  
} )a AKO`  
catch(Exception e){e.printStackTrace ();} -*~= 4m<  
} Dt%Gv0  
} \T`InBbf  
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k
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//打印回应的头信息 5^<X:1J$  
public void logResponseHead(HttpURLConnection con) EiQX*v  
{ 9utiev~
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for(int i=1;;i++) ![h+R@_(  
{ pM],-7UM  
String header=con.getHeaderFieldKey(i); )e(Rf!P{  
if(header!=null) UbNA|`H  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); jfP2n5X83  
Utility.log(header+" : "+con.getHeaderField(header)); \3JZ=/  
else m\o<a|  
break; 3=5K7F  
} K+ZJSfO6  
} dw#K!,g  
#?\$*@O  
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public void splitterStop() Xb?:dlu3  
{ tS!FnQg4  
bStop = true; Veo*-sl  
} _0N=~`'  
!m"LIa#/Cs  
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} a\;1%2a  
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8mjPa^A  
/* v%v(-, _q  
**FileAccess.java '#RzX8|v<  
*//文件访问(定位，写) K2$ fKju  
package NetFox; kW#,o9f\  
import java.io.*; XtY!fo*  
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public class FileAccessI implements Serializable{ 4<}!+X7m  
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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 8=QOp[w

 
RandomAccessFile oSavedFile; x93h{Kf  
long nPos; z"#iG
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public FileAccessI() throws IOException EQ 'L"  
{ )4:K@  
this("",0); Loz5[L  
} gZA[Sq
 
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public FileAccessI(String sName,long nPos) throws IOException o>WB,i^G  
{ <Qg).n>;z  
oSavedFile = new RandomAccessFile(sName,"rw"); 8(-V pU  
this.nPos = nPos; 4/KGrY!ck  
oSavedFile.seek(nPos); 4<V%7z_.B  
} 3y^PKIIrt  
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public synchronized int write(byte[] b,int nStart,int nLen) dbn9t7'{  
{ O[}{$NXw  
int n = -1; zs/4tNXw  
try{ `+DH@ce  
oSavedFile.write(b,nStart,nLen); h?_Cv*0q  
n = nLen; Kny0 (  
} eTg8I/)%B  
catch(IOException e) "/e_[_j  
{ (LiS9|J!  
e.printStackTrace (); :ohGG ,`Dh  
} d}D%%noIu  
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return n; 42/MBP`
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} !8g419Yg  
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} w8=&rzr8  
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/* f^JiaU4 [  
**SiteInfoBean.java 5(wmy-x\  
*/ @!p bR(8  
package NetFox; EPEWyGw  
8y:/!rRN  
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public class SiteInfoBean { mJxr"cwHl  
(vX) <Z !  
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private String sSiteURL; //Site's URL M)x6m|.=  
private String sFilePath; //Saved File's Path 0Q7teXRM  
private String sFileName; //Saved File's Name ( p(/  
private int nSplitter; //Count of Splited Downloading File yMG(FAyu  
z*V 8l*  

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public SiteInfoBean() 9sP;s^#t7U  
{//nSplitter的缺省值为5 j_I[k8z  
//default value of nSplitter is 5 In[rxT~K}Q  
this("","","",5); BiY-u/bH9a  
} zA%YaekJ  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) R$XHjb)  
{ WCTmf8f  
sSiteURL= sURL; e{Q;,jsh  
sFilePath = sPath; ai7R@~O:_k  
sFileName = sName; n~"qbtp}  
this.nSplitter = nSpiltter; BGd# \2  
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} ol0i^d*9F  
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public String getSSiteURL() 7vo8lnQ{  
{ 4,,DA2^!  
return sSiteURL; %p48=|+  
} _sb~eB~<(  
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a8WWFAC[  
public void setSSiteURL(String value) }/w]+f*  
{ m?<^b_a}  
sSiteURL = value; ~8 B]  
} {+~ JTrp  
-uKTEG[  
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public String getSFilePath() 0OXl`V`w  
{ A"e4
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return sFilePath; +>&i]x(b  
} YdZ9##IU3  
#<LJns\t   
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public void setSFilePath(String value) 85x34nT  
{ o%b6"_~%3  
sFilePath = value; bm*.*A]  
} &6^ --cc  
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216`rQ}z  
public String getSFileName() 2Z-[x9t  
{ 7|HIl=  
return sFileName; 4se6+oJe  
} E<ILZpP
 
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public void setSFileName(String value) w%?Zb[!&  
{ 5tI#UBha  
sFileName = value; zv7)JH7EV&  
} \0W0o5c$  
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public int getNSplitter() =F2`X#x_j  
{ {2%'=v  
return nSplitter; `;=-71Gn~  
} p[O\}MAd#  
86pA+c+U  
 0ijYE  
public void setNSplitter(int nCount) %aI,K0\  
{ i z
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nSplitter = nCount; ken.#>w  
} y|0!sNg  
} <vE
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/* o}&{Y2!x  
**Utility.java ]v/pMg#-  
*/ ,#czx3?4  
package NetFox; C hQ] d  
nQOzKw<j%  
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public class Utility { dVPY07P  
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public Utility() (wFoI}s  
{ 27+~!R~Yw  
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} m^\&v0  
A/"<o5(T(P  
//线程睡眠 Y_}_)n
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public static void sleep(int nSecond) UGlHe7  
{ 76o3Sge:  
try{ 7|o!v);uR  
Thread.sleep(nSecond); k*u6'IKi.4  
} a)4%sX
*I  
catch(Exception e) .EPv4[2%F8  
{ Qqi?DW1)-  
e.printStackTrace (); Z4X, D`s  
} Uqz.Q\A  
} QI'-I\Co  
NiFe#SLA  
//日志 .R@s6}C`}=  
public static void log(String sMsg) aZ|?i }  
{ em95ccs'-  
System.err.println(sMsg); =W;e9 6#  
} sq;!5qK  
S[gACEZ =  
3~Lsa"/  
public static void log(int sMsg) c5|sda{  
{ Vo6+|ztk|  
System.err.println(sMsg); vsyg u  
} n=PfV3B  
} u(fZ^  
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/* P^# 4m  
**TestMethod.java Y]*&\Ex"\  
*/ %Oo f/q  
package NetFox; \4LTViY]  
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public class TestMethod { IBvn q8\  
e/_QS}OA  
pGfGGY>i%  
public TestMethod() s_}6#;  
{ ///xx/weblogic60b2_win.exe ZPY&q&R  
try{ >&Oql9_  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); BzzZ.AH~  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Vhh=GJ  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 2X[oge0@  
fileFetch.start(); eX>*}pI  
} Gov.;hy  
catch(Exception e){e.printStackTrace ();} qo$ls\[X  
yoJ.[M4q  
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} hkyO_ns  
9J~\.:jH-  
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public static void main(String[] args) ^%!SKhRIK  
{ ";7xE#jRk  
new TestMethod(); ;c)( 'k<  
} WF-jy7+  
} $=Ns7Sbup  
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