http断点续传简单实现（java)

/* \T!,Z;zK  
**SiteFileFetch.java [mj=m
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*/ ,tDLpnB@;  
package NetFox; pMY7{z  
import java.io.*; [XH,~JZJj  
import java.net.*; CpK:u! Dn  
b~B'FD  
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public class SiteFileFetch extends Thread { /q8B | (U  
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SiteInfoBean siteInfoBean = null; //文件信息Bean J1w3g,  
long[] nStartPos; //开始位置 5s;@;V  
long[] nEndPos; //结束位置 C(UWir3mW?  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 !Pt4\  
long nFileLength; //文件长度 @4KKm@(p85  
boolean bFirst = true; //是否第一次取文件 -x:7K\=$SX  
boolean bStop = false; //停止标志 F/,6Jh  
File tmpFile; //文件下载的临时信息 "kC
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DataOutputStream output; //输出到文件的输出流 &ld<fa(w+2  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） }@/Ox  
public SiteFileFetch(SiteInfoBean bean) throws IOException y
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{ Qmb+%z  
siteInfoBean = bean; ;JgSA&'e  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 1]Cbi7  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); xFJT&=Af W  
if(tmpFile.exists ()) wWSw0 H/  
{ 2^"!p;WQ  
bFirst = false; kw} E0uY  
read_nPos(); :fnJp9c  
} ,izp^,`  
else (/Jy9=~  
{ xwW(WHdC]  
nStartPos = new long[bean.getNSplitter()]; (kyRx+gA  
nEndPos = new long[bean.getNSplitter()]; tOte[~,  
} U#- 5",X|  
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} *_mER`  

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public void run() B.smQt  
{ ("{vbs$;  
//获得文件长度 2yD ?f8P4  
//分割文件 9i lJ  
//实例FileSplitterFetch
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//启动FileSplitterFetch线程 TKbfZw  
//等待子线程返回 #;lEx'lKN  
try{ {X<_Y<  
if(bFirst) ^|vP").aQm  
{ :Ig9n:  
nFileLength = getFileSize(); Oiqc]4TL  
if(nFileLength == -1) k^cnNx  
{ F&^&"(H}  
System.err.println("File Length is not known!"); j|qdf3^f  
} 9eE FX7  
else if(nFileLength == -2) ?B)e8i<[f  
{ {zc*yV\  
System.err.println("File is not access!"); 8Fbt >-N<\  
} (lq%4h  
else DY/%|w*L  
{ X+ybgB4(  
for(int i=0;i<nStartPos.length;i++) :/Z1$xS  
{ M0e&GR8<z>  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); aI}htb{m`  
} cRCji^,KJ  
for(int i=0;i<nEndPos.length-1;i++) >{A)d<  
{ $GQEdVSNo  
nEndPos = nStartPos[i+1]; .b!HEi<F  
} KV'3\`v@LY  
nEndPos[nEndPos.length-1] = nFileLength; 9"L!A,&'  
} %,@e- &>  
} /}%C'  
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//启动子线程 _`laP5
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; *_Ih@f H  
for(int i=0;i<nStartPos.length;i++) R!\._m?\h  
{ _W,?_"[R=  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -- IewW  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), p]toDy-}  
nStartPos,nEndPos,i); JE@3UXg
  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); B[f:T%  
fileSplitterFetch.start(); jH;L7
 
} Fa
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .%\||1F<  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); I8IH\5
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 8Bxb~*  
nEndPos = " + nFileLength); Y9%zo~]-W'  
// fileSplitterFetch[nPos.length-1].start(); goD#2
lg  
/nt%VLms%  
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//等待子线程结束 z~1S/,Ca  
//int count = 0; $z5C+K@  
//是否结束while循环 >{rD3X"d  
boolean breakWhile = false; n2["Ln mO  
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while(!bStop) +<f+kh2L  
{ m8gU8a"(  
write_nPos(); /de~+I5AB~  
Utility.sleep(500); <4;L&3  
breakWhile = true; wqX!7rD/g)  
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for(int i=0;i<nStartPos.length;i++) E-?JHJloU  
{ t-]~^s  
if(!fileSplitterFetch.bDownOver) xR&Le/3+  
{ A{DE7gp!
 
breakWhile = false; WxtB:7J  
break; 1ZWr@,\L  
} P Qi=  
} 9; aOUs:<  
if(breakWhile) 8ROZ]Xh,x  
break; UGA``;f  
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//count++; pJ@->V_  
//if(count>4) B+ZhQW  
// siteStop(); =~k#<q1^  
} A_5M
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System.err.println("文件下载结束！"); w?R#ly  
} nYnv.5  
catch(Exception e){e.printStackTrace ();} X@:@1+U  
} H4ancmy  
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//获得文件长度 YH0utc  
public long getFileSize() Ve[&_(fP  
{ 6>Is-/hsy  
int nFileLength = -1; }FC(Z-g  
try{ 'L veCi_  
URL url = new URL(siteInfoBean.getSSiteURL()); <e-hR$  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2nB{oF-Z  
httpConnection.setRequestProperty("User-Agent","NetFox"); wD $sKd  
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int responseCode=httpConnection.getResponseCode(); }h9f(ZyJn  
if(responseCode>=400) wf,w%n  
{ ()(/9t  
processErrorCode(responseCode); VCvFCyAz  
return -2; //-2 represent access is error ~J|B  
} KU87WpjX  
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String sHeader; .^[{~#Pc*  
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for(int i=1;;i++) 9Cq"Szs  
{ W JG8E7  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 0M;aTM  
//Utility.log(in.readLine()); }r;#|=HR  
sHeader=httpConnection.getHeaderFieldKey(i); WCwM+D  
if(sHeader!=null) ~JDVoS;>jU  
{ sN@=Ri?\  
if(sHeader.equals("Content-Length")) !u=A9i!  
{ OF1Qr bj  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); j>|mpfU  
break; I?Q[ZH:M  
} @-aMj  
} QfI@=Kbg%#  
else 3t:/Guyom8  
break; &h;J_Ps  
} b("M8}o  
} 7\EY&KI"0  
catch(IOException e){e.printStackTrace ();} i
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catch(Exception e){e.printStackTrace ();} m4'x>Z  
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Utility.log(nFileLength); #;s5=aH  
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return nFileLength; n_P2l<F~/x  
} I_iXu;UX  
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//保存下载信息（文件指针位置） e<HHgC#J  
private void write_nPos() }/.GB5Ej  
{ 5<h:kZ"S^g  
try{ ]E}eM@xdD  
output = new DataOutputStream(new FileOutputStream(tmpFile)); }\hz@G<  
output.writeInt(nStartPos.length); p JM&R<i:  
for(int i=0;i<nStartPos.length;i++) _|s'0F/t  
{ fzW!-  
// output.writeLong(nPos); 9wpV} .(  
output.writeLong(fileSplitterFetch.nStartPos); U$wD'v3pw  
output.writeLong(fileSplitterFetch.nEndPos); t}f,j^`e  
} ~cb7]^#u1l  
output.close(); "\l#q$1h  
} asKAHVT(  
catch(IOException e){e.printStackTrace ();} n
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catch(Exception e){e.printStackTrace ();} NrWgaPO)i  
} =4:]V\o):'  
)o_Pnq9_  
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//读取保存的下载信息（文件指针位置） `
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private void read_nPos() ) 0|X];sD  
{ .dTXC'  
try{ H{VJS Jc{  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); )]3_o!o
  
int nCount = input.readInt(); ,p9>/)l  
nStartPos = new long[nCount]; R}HNi(%"  
nEndPos = new long[nCount]; dNT
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for(int i=0;i<nStartPos.length;i++) W&;,7T8@  
{ H.*aVb$  
nStartPos = input.readLong(); +VRM:&  
nEndPos = input.readLong(); 9]PMti  
} T<K/bzB3z  
input.close(); t-VU&.Y  
} whh#J (  
catch(IOException e){e.printStackTrace ();} @Avve8S  
catch(Exception e){e.printStackTrace ();} d3tr9B  
} @$!rgLyL[  
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private void processErrorCode(int nErrorCode) y.Y;<UGu  
{ 3&KRG}5  
System.err.println("Error Code : " + nErrorCode);
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} yp"h$  
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//停止文件下载 c^x5 E`{  
public void siteStop() {&0u:  
{ 7L$\S[E  
bStop = true; agp7zw=N  
for(int i=0;i<nStartPos.length;i++) #(G"ya  
fileSplitterFetch.splitterStop(); pRGag~h|E  
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} GtpBd40"  
} -X_dY>>s  
//负责部分文件的抓取 9|qzFmE#  
**FileSplitterFetch.java rIQ%X`Y  
*/ D/bF  
package NetFox; ,qT+Vqpr{  
f yhBfA:u  
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import java.io.*; qw6i|JM%  
import java.net.*; _DLELcH Y  
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public class FileSplitterFetch extends Thread { FG)(,?q  
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String sURL; //File URL
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long nStartPos; //File Snippet Start Position p&k%d, *  
long nEndPos; //File Snippet End Position kV@?Oj.&I,  
int nThreadID; //Thread's ID rBZ0Fx$/[  
boolean bDownOver = false; //Downing is over W}'l8z]   
boolean bStop = false; //Stop identical Mew,g:m:  
FileAccessI fileAccessI = null; //File Access interface jhH&}d9  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException !Wz4BBU8o  
{ `CY c>n"  
this.sURL = sURL; WYd9p;k  
this.nStartPos = nStart; r2T$ ;m.  
this.nEndPos = nEnd; vq:?a  
nThreadID = id; 0^K2"De  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 a[@Y>  
} rk &ME#<r  
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public void run() i$lp8Y2ih  
{ 4)?s?+  
while(nStartPos < nEndPos && !bStop) RwUosh\W  
{ TW-^C;   
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try{ ;L[N.ZY!  
URL url = new URL(sURL); @K\hgaQ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2hsRYh  
httpConnection.setRequestProperty("User-Agent","NetFox"); VWrb`p@  
String sProperty = "bytes="+nStartPos+"-"; W#kd[Wi  
httpConnection.setRequestProperty("RANGE",sProperty); @]7s`?  
Utility.log(sProperty); $g_|U:,  
.S*VYt%K7  
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InputStream input = httpConnection.getInputStream(); 0( q:K6zI}  
//logResponseHead(httpConnection); )3.=)?XW  
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byte[] b = new byte[1024]; Tly*i"[&  
int nRead; SvQ!n4 $  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) *yYeqm  
{ 8(g}/%1mt3  
nStartPos += fileAccessI.write(b,0,nRead); p# JPLCs  
//if(nThreadID == 1) ';xp+,'}\  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); #=N6[:,  
} @6b4
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)zkr[;j~`  
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Utility.log("Thread " + nThreadID + " is over!"); @cc}[Uw4B  
bDownOver = true; lJdrrR)wg  
//nPos = fileAccessI.write (b,0,nRead); ai"N;1/1O|  
} 8Y [4JXUK  
catch(Exception e){e.printStackTrace ();} v^aI+p6  
} 9XmbH
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} pgBIYeY,  
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//打印回应的头信息 }kSP p  
public void logResponseHead(HttpURLConnection con) ndu$N$7+  
{ b8**M'k  
for(int i=1;;i++) %E[ $np>  
{ 8ib e#jlg  
String header=con.getHeaderFieldKey(i); |

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if(header!=null) g%okYH?  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); |h& q  
Utility.log(header+" : "+con.getHeaderField(header)); mFt\xGa  
else mYbu1542'n  
break; wRg[Mu,Q5  
} e!vWGnY  
} baGV]=j  
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:  
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public void splitterStop() 08/Tk+  
{ z9w]{Zd_,d  
bStop = true; NIHcX6Nw  
} U/ax`_  
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} ']N\y6=fn9  
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/* <5zr|BTF]F  
**FileAccess.java Zt}b}Bz  
*//文件访问(定位，写) m[v%Qe|~  
package NetFox; r`i.h ^2De  
import java.io.*; 8X/SNRk6p  
vAjog])9s  
.  LeS-  
public class FileAccessI implements Serializable{ 2 ,krVb?<  
=3PZGdWD  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 lo-VfKvy  
RandomAccessFile oSavedFile; 5a4i)I63o  
long nPos; %~P3t=r  
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public FileAccessI() throws IOException jOZ>^5}  
{ E85TCS1  
this("",0); AoY!f'Z  
} %qEp{i
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public FileAccessI(String sName,long nPos) throws IOException 8( Q  
{ 5 BeU/  
oSavedFile = new RandomAccessFile(sName,"rw"); Zzmo7kFx3  
this.nPos = nPos; 7!;zkou  
oSavedFile.seek(nPos); V P(JV  
} 7Kpv fyL{  
2InM(p7j~K  
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public synchronized int write(byte[] b,int nStart,int nLen) z\YLO%Mm  
{ Mm!;+bM%  
int n = -1; J!">L+Zcx  
try{
j
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oSavedFile.write(b,nStart,nLen); Kd\d>&b  
n = nLen; X9?0`6Li  
} HY;kV6g{P  
catch(IOException e) ?5F;4oR2g  
{ 3Kq/V_  
e.printStackTrace (); ru|*xNXKgC  
} h-
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return n; GyVuQ51  
} g?*D)WU  
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} ])q,mH  
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u  
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/* ?!
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**SiteInfoBean.java bdEIvf7  
*/ lqa~ZF*  
package NetFox; yqR]9"a  
E33WT{H&_'  
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public class SiteInfoBean { 6$l?D^{  
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private String sSiteURL; //Site's URL ;wTc_i  
private String sFilePath; //Saved File's Path ]f}(iD  
private String sFileName; //Saved File's Name X~/-,oV=A  
private int nSplitter; //Count of Splited Downloading File qyh]v[  
#o,FVYYj  
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public SiteInfoBean() vP\6=71Y  
{//nSplitter的缺省值为5 74&{GCL  
//default value of nSplitter is 5 ;|W:,a{kS  
this("","","",5); h iK}&  
} L(9AcP  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) D(WV
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{ Nq|y\3]  
sSiteURL= sURL;
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sFilePath = sPath; nB]mj_)R^  
sFileName = sName; Wtp=1  
this.nSplitter = nSpiltter; 0k4XVd+Nv  
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} 2|U6dLZ!  
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8 qZbsZi4  
public String getSSiteURL() (cV1Pmn  
{ lR
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return sSiteURL; (f~}5O<  
} Kaaz,C.$^  
:nfy=*M#  
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public void setSSiteURL(String value) 2izBB,# "  
{ F+j"bhe  
sSiteURL = value; 4/v[.5  
} ~QUN O~  
.[1@wW&L  
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public String getSFilePath() 6Q{OM:L/;.  
{ &PFq(4  
return sFilePath; IWI$@dng6  
} ~=<uYv?0s  
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K@:Ab'(P^|  
public void setSFilePath(String value) @gmo;8?k  
{ y{~tMpo<  
sFilePath = value; W7{^/s5r  
} {Z Ld_VGW  
dxH.  
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public String getSFileName() {XD':2E  
{ # @7I  
return sFileName; |CQ0{1R1  
} 09{s'  
2^nws  
}wI+eMr  
public void setSFileName(String value) |$+/IxDP  
{ zZey
 
sFileName = value; 4Y4zBD=<  
} }([}A`@  
'MNCJ;A@V  
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public int getNSplitter() @2hOy@V  
{ WMWUP ZsGS  
return nSplitter; ou`KkY||  
} 2]FRIy d  
)HvBceN  
/}iBrMD{[  
public void setNSplitter(int nCount) ]v?jfy  
{ | h+vdE8  
nSplitter = nCount; ] ;CJ6gM~  
} 8!@}\6qM  
} 7#7|+%W0  
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7r.~L  
/*
/-WmOn*  
**Utility.java "/2kf)l{4  
*/ Pv3G?u=4  
package NetFox; S/RChg_L5  
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public class Utility { 0"ooHP$1  
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public Utility() }7P[%(T5  
{ 6BM$u v4  
(A=Z,ed  
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} E\cX  
]<c\+9  
//线程睡眠 $jv"$0Fc  
public static void sleep(int nSecond) Y>~jho  
{ XD_!5+\H1  
try{ ?[Ma" l>  
Thread.sleep(nSecond); OPogH=vf  
}
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catch(Exception e) } j;es(~D  
{ Dk8@x8  
e.printStackTrace (); jpoNTl'  
} ?I"?J/zm  
} Mm9*$g!R  
XV`8Vb  
//日志 ;d]vAj  
public static void log(String sMsg) gFfKK`)}D'  
{ -%{+\x2  
System.err.println(sMsg); 2$A"{2G  
} J |U
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S-</(,E}|  
}m7$,'C%P  
public static void log(int sMsg) )ZFc5m^+u  
{ DnW/q  
System.err.println(sMsg); &FYv4J  
} `~41>mM%  
} &!M6{O=~  
#uICHt3  
|B64%w>Y  
/* 036QV M$  
**TestMethod.java bqx2lQf,_  
*/ HEhBOER?  
package NetFox; )p:
+!sX(  
&n0Ag]$P  
=Mxu,A  
public class TestMethod { /g!Xe]Ss  
$&Z#2 X.  
tAujm*|&  
public TestMethod() aH8]$e8_,\  
{ ///xx/weblogic60b2_win.exe ;W FiMM\  
try{ ez5>V7Y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); k72NXagh  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); YNKvR  
SiteFileFetch fileFetch = new SiteFileFetch(bean); W
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fileFetch.start(); wqJl[~O$  
} pEX Q  
catch(Exception e){e.printStackTrace ();} 1&9w]\Ae7l  
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} %[azMlp<  
*!3qO^b?  
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public static void main(String[] args) Hc8!cATQk  
{ J6rWe  
new TestMethod(); %,aSD#l`f  
} x{Dw?6TP  
} 'SrDc'?  
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