http断点续传简单实现（java)

/* Ps{vN ~}  
**SiteFileFetch.java e`OQ6|.k8  
*/ [m%]C  
package NetFox; y*6/VSRkt4  
import java.io.*; "?<h,Hvi  
import java.net.*; 9%1J..c  
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public class SiteFileFetch extends Thread { "Mhn?PTq  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 51y#AQ@  
long[] nStartPos; //开始位置 h72CGA|  
long[] nEndPos; //结束位置 v+8Ybq  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 K1Uq`TJ  
long nFileLength; //文件长度 L(sT/  
boolean bFirst = true; //是否第一次取文件 ;{q*  
boolean bStop = false; //停止标志 PB?2{Cj
 
File tmpFile; //文件下载的临时信息 c&FOt  
DataOutputStream output; //输出到文件的输出流 !a-B=pn!]  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ! Dj2/][  
public SiteFileFetch(SiteInfoBean bean) throws IOException V; CPn  
{ S!+>{JyQ  
siteInfoBean = bean; y@It#!u0  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); o]<9wc:FZ  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); a^pbBDi W  
if(tmpFile.exists ()) Jazgn5  
{ A.dbb'^  
bFirst = false; 'W yWO^Bdk  
read_nPos();
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} 4^M"V5tDx  
else :O$bsw:3w<  
{ OZnKJ<  
nStartPos = new long[bean.getNSplitter()]; W5=)B`v  
nEndPos = new long[bean.getNSplitter()];  o?m/  
} h /^bRs`;  
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} LO>42o?/i  
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public void run() R&J?XQ  
{ 7.6L1srV  
//获得文件长度 ?s3S$Ih  
//分割文件 `fTM/"  
//实例FileSplitterFetch ,"XiI$Le  
//启动FileSplitterFetch线程 +
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//等待子线程返回 c38XM]Jeq  
try{ -THMTRFz  
if(bFirst) 'A3skznX{  
{ fe,6YXUf  
nFileLength = getFileSize(); =I)43ahd  
if(nFileLength == -1) kFV, Fg  
{ . R/y`:1:W  
System.err.println("File Length is not known!"); ;}"Eqq:  
} zdd-n[%@V  
else if(nFileLength == -2) ,^97Ks ;  
{ IT&,?u%  
System.err.println("File is not access!"); %S}uCqcAK  
} 6/Xs}[iJ  
else dK4rrO  
{ ]L7A$sTUQ  
for(int i=0;i<nStartPos.length;i++) 2R.LLE  
{ _Uq' N0U  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); KP>9hEh  
} ^}B,0yUu'  
for(int i=0;i<nEndPos.length-1;i++) }$4z$&  
{ +8T^
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nEndPos = nStartPos[i+1]; v|o{AL:ei  
} ,0q1Id  
nEndPos[nEndPos.length-1] = nFileLength; ]MosiMJF  
} X["xC3 i  
} %.<_+V#h  
W%-XN  
mV$ebFco0  
//启动子线程 4n@lrcq(  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; f,KB BBbG  
for(int i=0;i<nStartPos.length;i++) cN8Fn4g
q  
{ dQ.#8o=  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), \`2'W1O  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), t'l4$}(  
nStartPos,nEndPos,i); Mm
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); r(46jV.sD:  
fileSplitterFetch.start(); P*OG`%y  
} _!@:@e)yB{  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), YAOfuas]j  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); d*0RBgn  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", !S#3mT-  
nEndPos = " + nFileLength); 4JAz{aw'b  
// fileSplitterFetch[nPos.length-1].start(); .qO4ceW2-~  
{_-kwg{"(  
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//等待子线程结束 !i^"3!.l,]  
//int count = 0; 2Lf,~EV  
//是否结束while循环 Cp6S2v I  
boolean breakWhile = false; T8x)i\<  
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$`E?=L`$  
while(!bStop) q[,p#uJ]  
{ yu6{6[  
write_nPos(); 6*q1%rs:w  
Utility.sleep(500); ^{4BcM7eH  
breakWhile = true; =cS&>MT  
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for(int i=0;i<nStartPos.length;i++) 25$_tZPAI  
{ G?1GkR  
if(!fileSplitterFetch.bDownOver) t]$n~!  
{ usB*Wn8  
breakWhile = false; w={q@. g%  
break; o@e/P;E  
} %N*[{j= ^  
} i[!|0U`p  
if(breakWhile) J rx^  
break; g<W]NYm  
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//count++; &q-&%~E@  
//if(count>4)  AG@gOm  
// siteStop(); c>_ti+  
} Hd|[>4Z  
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System.err.println("文件下载结束！");  ES~b f  
} u
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catch(Exception e){e.printStackTrace ();} q!y.cyL  
} aDF@AS  
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//获得文件长度 pAE (i7  
public long getFileSize() yV(#z2|  
{ 79v+ze  
int nFileLength = -1; ,|:.0g[n  
try{ qzUiBwUi@  
URL url = new URL(siteInfoBean.getSSiteURL()); y2jv84 M  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ShI1f  
httpConnection.setRequestProperty("User-Agent","NetFox"); .~f )4'T 9  
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int responseCode=httpConnection.getResponseCode(); Kjd3!%4mB  
if(responseCode>=400) 0)ohab  
{ :y-;
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processErrorCode(responseCode); .<%tu 0  
return -2; //-2 represent access is error z1J)./BO  
} >1j#XA8  
q]?qeF[  
9zwD%3Ufn  
String sHeader; 4X+xh|R:U  
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for(int i=1;;i++) I%YwG3uR  
{ 3K &637  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); W{F)YyR{.  
//Utility.log(in.readLine()); ys9:";X;}  
sHeader=httpConnection.getHeaderFieldKey(i); >dl5^  
if(sHeader!=null) 4YfM.~ 6  
{ ,*|Q=  
if(sHeader.equals("Content-Length")) 4$xVm,n|  
{ Nk7y2[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); I%5vI}  
break; t*IePz]/  
} Q,KNZxT,q  
} 6!\V|  
else .-Lrrk)R+  
break; U@Od
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} Msqqjhoy  
} 9\Jc7[b  
catch(IOException e){e.printStackTrace ();} ]-\68bN  
catch(Exception e){e.printStackTrace ();} 4z<c8 E8  
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Utility.log(nFileLength); RE>Q5#
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return nFileLength; IuXgxR%  
} cp`Jep<T  
$${I[2R)  
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//保存下载信息（文件指针位置） v"k ?e  
private void write_nPos() ^*Za
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{ :uCwWv  
try{ "\o#YC  
output = new DataOutputStream(new FileOutputStream(tmpFile)); w6vbYPCN  
output.writeInt(nStartPos.length); fd'kv  
for(int i=0;i<nStartPos.length;i++)  S_P&Fv  
{ <
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// output.writeLong(nPos); l U/Xi  
output.writeLong(fileSplitterFetch.nStartPos); I
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output.writeLong(fileSplitterFetch.nEndPos); cGV%=N^BE<  
} KQfWpHwfj  
output.close(); )>ZT{eF  
} n41#  
catch(IOException e){e.printStackTrace ();} d5'Q1"{  
catch(Exception e){e.printStackTrace ();} ]o] VS  
} Lz 1.+:Ag  
&|Gg46P7  
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//读取保存的下载信息（文件指针位置） '[$KG  
private void read_nPos() ,JwX*L<:  
{ ED` 1)1<  
try{ &#PPXwmR  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 2.^{4 1:  
int nCount = input.readInt(); rH7Cv/Y  
nStartPos = new long[nCount]; ~5P9^`KNH  
nEndPos = new long[nCount]; }097[-g7  
for(int i=0;i<nStartPos.length;i++)
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{ 'zUV(K?2]  
nStartPos = input.readLong(); |m's)  
nEndPos = input.readLong(); OJe!K:  
} ]9YA~n\  
input.close(); u> {aF{  
} 'yiv.<4  
catch(IOException e){e.printStackTrace ();} D6VdgU|  
catch(Exception e){e.printStackTrace ();} SJiQg-+<Uf  
} rj=as>6B  
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private void processErrorCode(int nErrorCode) 0nt@}\j  
{ DtANb^  
System.err.println("Error Code : " + nErrorCode); !<];N0nt#  
} %+'Ex]B  
{"]!zL  
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//停止文件下载 irlFB#..  
public void siteStop() D\Ez~.H  
{ tX^6R  
bStop = true; ]aPf-O*  
for(int i=0;i<nStartPos.length;i++) (G|!
{  
fileSplitterFetch.splitterStop(); ](JrEg$K  
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} [5&k{*}}  
} `CWh
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//负责部分文件的抓取 (2b${Q@V  
**FileSplitterFetch.java cW*v))@2  
*/ 5UQ{qm*Q  
package NetFox; fqI67E$59  
)c11_1;  
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import java.io.*; gKb,Vrt  
import java.net.*; X.<3/  
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public class FileSplitterFetch extends Thread { PMsb"=Ds  
!=YEhQ-  
?|ZbQz(bL  
String sURL; //File URL Ck/44Wfej  
long nStartPos; //File Snippet Start Position fTj@/"a  
long nEndPos; //File Snippet End Position gXI-{R7Me  
int nThreadID; //Thread's ID d[6 'w ?  
boolean bDownOver = false; //Downing is over D9+qT<ojN  
boolean bStop = false; //Stop identical WaB0?jI  
FileAccessI fileAccessI = null; //File Access interface 6xDk3  
icb)JZ1K  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 1{N+B#*<[X  
{ CU|E-XPW  
this.sURL = sURL; i8?oe%9l  
this.nStartPos = nStart; [!)
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this.nEndPos = nEnd; 1J[$f>%n]  
nThreadID = id; $I9&cNPv  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 LAC&W;pJ"  
} !yv>e7g^  
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public void run() ,P9F*;Dj  
{ 4bk`i*-O  
while(nStartPos < nEndPos && !bStop) [RXLR#  
{ Fv]6an.  
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try{ O84:ejro  
URL url = new URL(sURL); (GF}c\=T7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ''auu4vF  
httpConnection.setRequestProperty("User-Agent","NetFox"); K/zb6=->  
String sProperty = "bytes="+nStartPos+"-"; zr!7*, p  
httpConnection.setRequestProperty("RANGE",sProperty); OB.rETg  
Utility.log(sProperty); G_1r&[N3  
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InputStream input = httpConnection.getInputStream(); bD{tsxm[9  
//logResponseHead(httpConnection); q0}u%Yz  
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byte[] b = new byte[1024]; w
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int nRead; FO/cEu  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) z%E(o%l8  
{ Tw';;euw  
nStartPos += fileAccessI.write(b,0,nRead); ZbC$Fk,,I&  
//if(nThreadID == 1) lG-B)
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); <}lah%4F  
} [2,D]e  
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}K?b2 6`  
Utility.log("Thread " + nThreadID + " is over!"); ;t*SG*Vi  
bDownOver = true; 
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//nPos = fileAccessI.write (b,0,nRead); (l%?YME  
} 68j1svz9  
catch(Exception e){e.printStackTrace ();} ,< g%
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} 2Vti|@JYp  
} Jk%5Fw0  
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//打印回应的头信息 %.d.h;^T  
public void logResponseHead(HttpURLConnection con) m]V#fRC  
{ \d;)U4__!  
for(int i=1;;i++) +IS6l*_y>6  
{ )P7ep  
String header=con.getHeaderFieldKey(i); .I>rX#aNt  
if(header!=null) >/74u/&  
//responseHeaders.put(header,httpConnection.getHeaderField(header));
rA ={;`  
Utility.log(header+" : "+con.getHeaderField(header)); se.HA  
else 2V]a+Cgk  
break; \i+AMduAo  
} EPJ>@A>;D  
} `V9bd}M%~;  
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public void splitterStop() bVz<8b6h'-  
{ +c/!R|h=S  
bStop = true; :|9vMM^$  
} ;"cQ)=s9Y  
@Y`Z3LiR$  
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} ]A}ZaXd  
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/* NxF:s,a6  
**FileAccess.java W!$U{=  
*//文件访问(定位，写) |Ogh-<|<  
package NetFox; x%s1)\^A  
import java.io.*; .tKBmq0xo"  
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public class FileAccessI implements Serializable{ gHc1_G]  
;:Z5Ft m  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 FS5iUH+5  
RandomAccessFile oSavedFile; =~JVU  
long nPos; iDcTO}  
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public FileAccessI() throws IOException j_d}?jh  
{ p>eYi \'  
this("",0); ^~N:lW#=  
} tm/>H  
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[R1|=kG
U  
public FileAccessI(String sName,long nPos) throws IOException qqo#H O  
{ l$1?@l$j  
oSavedFile = new RandomAccessFile(sName,"rw"); ZxSnqbyA*  
this.nPos = nPos; QDW,e]A  
oSavedFile.seek(nPos); TgjjwcO Y  
} Q3%]  
k={1zl ;  
sCw>J#@2>  
public synchronized int write(byte[] b,int nStart,int nLen) U
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{ x%`YV):*  
int n = -1; Wu* 4r0  
try{ va_u4  
oSavedFile.write(b,nStart,nLen); /ojx$Um  
n = nLen; qCI7)L`  
} \]4EAKJE  
catch(IOException e) qpFxl  
{ {St-
 
e.printStackTrace (); YvN]7tcb  
} 'k]~Q{K$  
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return n; m8PS84."]M  
} ,,G"EF0A  
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} T16gq-h'  
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/* p?#T^{Quz~  
**SiteInfoBean.java ECA<%
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*/ cH*")oD  
package NetFox; @.$- ^-  
@gbW:  
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public class SiteInfoBean { a9;KS>~bq  
OQfFS+6  
hFm^Fy[R  
private String sSiteURL; //Site's URL ~C^:SND7  
private String sFilePath; //Saved File's Path #<==7X#  
private String sFileName; //Saved File's Name \,Ws=9f  
private int nSplitter; //Count of Splited Downloading File @@^iN~uf  
y akRKiz\  
9tv,,I;iU  
public SiteInfoBean() bwhH2^ !  
{//nSplitter的缺省值为5 "[P3b"=gW  
//default value of nSplitter is 5 MG=8`J-`  
this("","","",5); O'IU1sU  
} Q<u?BA/  
:8eI_X  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) #S9J9k  
{ {|>Wwa2e  
sSiteURL= sURL; [m{sl(Q  
sFilePath = sPath; %m dtVQ@  
sFileName = sName; J;Z2<x/H  
this.nSplitter = nSpiltter; O<Q8%Az  
&kzys
v-_  
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} z]rr Q=dAA  
m-azd~r[  
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public String getSSiteURL() ]i(/T$?~  
{ =q]!"yU[d  
return sSiteURL; I ?Dp*u*  
} o$</At  
jr0j0$BF  
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public void setSSiteURL(String value) 8cOft ;|qB  
{ oDu6W9+  
sSiteURL = value; JqMF9|{H  
} 6Jq[]l"v  
,k~' S~w.  
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public String getSFilePath() V6P-?Nd  
{ p&RC#wYu  
return sFilePath; 04dz?`HuB  
} +={
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public void setSFilePath(String value) 131(0nl)=I  
{
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sFilePath = value; DNq(\@x[!  
} s*la`(x  
l[:Aq&[o3  
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public String getSFileName() M{5AQzvs  
{ R]X 0D.  
return sFileName; vb]kh_  
} uEJ8Lmi
 
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public void setSFileName(String value) y8s!sO  
{ -JgNujt#9  
sFileName = value; M]r?m@)  
} =w+8q1!o  
:K^J bQ  
V2}\]x'1  
public int getNSplitter() PhC3F4  
{ :CE4< {V  
return nSplitter; KL=<s#
 
} U&WEe`XM  
-%"PqA/1zj  
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public void setNSplitter(int nCount) cw!,.o%cD  
{ =J]WVA,GqA  
nSplitter = nCount; |~BnE  
} &$/ #"lW,V  
} d)vP9vXy  
oV:oc,  
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/* XJe=+_K9  
**Utility.java ffmtTJFC5  
*/ eo9/  
package NetFox; ~I5hV}ZT  
>E<ib[vK[  
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public class Utility { &kIeW;X  
VGQ~~U7}@  
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public Utility() uTR
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{ QnVr)4"  
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} DD$>3`  
W\kli';jyC  
//线程睡眠 y,nmPX?]n  
public static void sleep(int nSecond) VQla.Y  
{ aL;!BlU8v  
try{ mcez3gH  
Thread.sleep(nSecond);  JaY"Wfc  
} 12n:)yQy  
catch(Exception e) &Pr\n&9A  
{ Zigv;}#  
e.printStackTrace (); [HQ)4xG  
} *z0d~j*W;  
} Lg7A[\c ~  
EhHxB fAQ  
//日志 en< $.aY  
public static void log(String sMsg) {Uw 0zC  
{ e NIzI]~  
System.err.println(sMsg); O6;"cUv  
} l\s!A&L  
pIlEoG=[_  

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public static void log(int sMsg) <:&vAX L  
{ 2cYBm^o|x  
System.err.println(sMsg); i 6G40!G=)  
} _!',%+  
} YqX$a~  
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f,HUr% @  
/* sApix=Lr  
**TestMethod.java ,Z"<-%3  
*/ EG>?>K_D  
package NetFox; !?>V^#c  
}S/i3$F0~  
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public class TestMethod { QadguV6|  
-G,}f\Cg  
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public TestMethod() [%.v;+L  
{ ///xx/weblogic60b2_win.exe /d3Jd.l!  
try{ MoIh=rw  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); :skR6J  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); x z_sejKB  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 6TW7E}a.  
fileFetch.start(); A8J
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} 7<yc:}9nx  
catch(Exception e){e.printStackTrace ();} lgOAc,  
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} V"4Z9Qg}  
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public static void main(String[] args) j!u)V1,  
{ 9-ozrw8t  
new TestMethod(); bU! v  
} cl~Yx4  
} n"(!v7YNp  
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