http断点续传简单实现（java)

/* ovXU +8  
**SiteFileFetch.java ' pN[H\Ia  
*/ .91@T.  
package NetFox;
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import java.io.*; ye^*Z>|  
import java.net.*; (/qOY  
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public class SiteFileFetch extends Thread { ~NV 8avZ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ,wYA_1$$H  
long[] nStartPos; //开始位置 yQz6K6p  
long[] nEndPos; //结束位置 ?h|&kRq  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 G4;5$YGG  
long nFileLength; //文件长度 QW
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boolean bFirst = true; //是否第一次取文件 [:BD9V  
boolean bStop = false; //停止标志 I6e[K(7NY  
File tmpFile; //文件下载的临时信息 Cm"7f!(#  
DataOutputStream output; //输出到文件的输出流 _c$F?9:  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） A)%!9i)  
public SiteFileFetch(SiteInfoBean bean) throws IOException p6c&vEsNj  
{ {9Ug9e{ ~  
siteInfoBean = bean; %o  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); [,0[\NC  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 2 r';)8:  
if(tmpFile.exists ()) Ys@OgdS@:  
{ V'^E'[Dd{  
bFirst = false; I83 _x|$FZ  
read_nPos(); %M5{-pJ|C  
} or qL0i  
else e.VQ!)>  
{  NIh?2w"\  
nStartPos = new long[bean.getNSplitter()]; b!4Z~d0=  
nEndPos = new long[bean.getNSplitter()]; ?#~km0~F)  
} q@&6&cd  
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} SVn $!t  
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public void run() 9<Ks2W.N  
{ A}4 ",  
//获得文件长度 Tf40lv+{  
//分割文件 +5x{|!Pn  
//实例FileSplitterFetch AL{iQxQ6  
//启动FileSplitterFetch线程 e'|IRhr  
//等待子线程返回 -2B3 xIZJ  
try{ pEp$J;   
if(bFirst) HChlkj'7w0  
{ |)*9BN  
nFileLength = getFileSize(); s4`,
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if(nFileLength == -1) 7{lWg x  
{ NjbIt=y  
System.err.println("File Length is not known!"); : G'a
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} v^dQ%+}7>  
else if(nFileLength == -2) l4gZHMh
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{ m.68ctaa  
System.err.println("File is not access!"); Ou`;HN;
[  
} "&C>=  
else c'DNO~H  
{ 3b?8<*  
for(int i=0;i<nStartPos.length;i++) Y|6gg  
{ =Eb$rc)
 
nStartPos = (long)(i*(nFileLength/nStartPos.length)); lhX4MB"  
} 4_
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for(int i=0;i<nEndPos.length-1;i++) K;ocs?rk/  
{ O%f{\Fr  
nEndPos = nStartPos[i+1]; T"3:dkQw  
} 2cjbb kq  
nEndPos[nEndPos.length-1] = nFileLength; &2nICAN[  
} ;+1ooeU  
} /r8sL)D+  
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//启动子线程 z.|[g$F  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 5+2qx)FZ  
for(int i=0;i<nStartPos.length;i++) CfT(a!;Eox  
{ ~ike&k{  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), @&x'.2[nv  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), A ^t _"J  
nStartPos,nEndPos,i); ,Jx.Kj.,  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); EE*|#  
fileSplitterFetch.start(); LLL;SNY  
} A2!pbeG  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), M/,lP  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); b7y#uL1AE  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ",
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nEndPos = " + nFileLength); kQp*+ras  
// fileSplitterFetch[nPos.length-1].start(); 2UIZ<#|D>s  
p +nh]  
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//等待子线程结束 _gEojuaN  
//int count = 0; ;oO_5[,M  
//是否结束while循环 ?Yx2q_KZk  
boolean breakWhile = false; Q!r&vQ/g  
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while(!bStop) P$]
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{ lavy?tFer  
write_nPos(); )%<,JD  
Utility.sleep(500); x=-(p}0o;<  
breakWhile = true; v4K! BW  
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for(int i=0;i<nStartPos.length;i++) =q>lP+  
{ <m

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if(!fileSplitterFetch.bDownOver) I Bko"|e@  
{ A H=%6oT2  
breakWhile = false; S;u.Ds&  
break; qO/3:-  
} \6bvk_
 
} `l6OQdB3W  
if(breakWhile) 138v{Z  
break; +p&zM3:9w  
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@ 'c(q=K;  
//count++; !E|R3eX_  
//if(count>4) 8C[eHC*r  
// siteStop(); I!}V+gu=  
} 2b
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System.err.println("文件下载结束！");  E(wS6  
}  w%::
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catch(Exception e){e.printStackTrace ();} |`pBI0Sjo  
} _yF@k~ h  
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atW^^4:  
//获得文件长度 hsJ^Au=})w  
public long getFileSize() nf[KD,f  
{ i[MBO`FF  
int nFileLength = -1; EQk omjv  
try{  deq5u>  
URL url = new URL(siteInfoBean.getSSiteURL()); +Z-{6C  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); C1(RgY|  
httpConnection.setRequestProperty("User-Agent","NetFox"); %%I:L~c  
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int responseCode=httpConnection.getResponseCode(); x>,wmk5)  
if(responseCode>=400) ~C3J-
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{ i
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processErrorCode(responseCode); XH0o8\.  
return -2; //-2 represent access is error X\w["!B  
} o( mA(h  
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String sHeader; mkPqxzxbrL  
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for(int i=1;;i++) O/$41mK+!  
{ ZsCwNZR  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); XiV K4sD8  
//Utility.log(in.readLine()); NH:Bdl3  
sHeader=httpConnection.getHeaderFieldKey(i); ,aq>9\pi  
if(sHeader!=null) N)a5~<fBG  
{ !KT.p2\  
if(sHeader.equals("Content-Length")) t/%[U,m  
{ 90,UhNz9D  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); h,-i\8gq  
break; fZS'e{V  
} /J Y6S  
} `Fe/=]<$  
else 3RI6+Cgmn  
break; @3 +   
} lPC{R k.\C  
} ^vv1cft  
catch(IOException e){e.printStackTrace ();} T-lP
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catch(Exception e){e.printStackTrace ();} oK<H/76x  
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Utility.log(nFileLength); ar'VoL}  

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return nFileLength; blP8"(U  
} x
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//保存下载信息（文件指针位置） ep`8LQf  
private void write_nPos() EG_P^<z  
{ mq(K_  
try{ >MhZ(&iD  
output = new DataOutputStream(new FileOutputStream(tmpFile)); HCYy9  
output.writeInt(nStartPos.length); ae2I,Qt%  
for(int i=0;i<nStartPos.length;i++) -]YsiE?r  
{ muBl~6_mb2  
// output.writeLong(nPos); P!)F1U]!  
output.writeLong(fileSplitterFetch.nStartPos); t:,lz8Y~  
output.writeLong(fileSplitterFetch.nEndPos); EiDpy#f}  
} '!4\H"t  
output.close(); -- IewW  
} p]toDy-}  
catch(IOException e){e.printStackTrace ();} naeppBo  
catch(Exception e){e.printStackTrace ();} l Dwq[ I]w  
} }XRfHQk  
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//读取保存的下载信息（文件指针位置） D$D;'Kij  
private void read_nPos() @00&J~D  
{ Q'j00/K  
try{ eSW}H_3  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); -:Juxh  
int nCount = input.readInt(); V.yDZ"  
nStartPos = new long[nCount]; dWo$5Bls<A  
nEndPos = new long[nCount]; |h((SreO  
for(int i=0;i<nStartPos.length;i++) hsQ*ozv[)  
{ k>E/)9%ep2  
nStartPos = input.readLong(); 3cNr~`7  
nEndPos = input.readLong(); 'k<~HQr  
} K8QEHc:  
input.close(); ,ob)6P^rw  
} [W dxMU  
catch(IOException e){e.printStackTrace ();} JxRn)D  
catch(Exception e){e.printStackTrace ();} .g=D70  
} 78]( ZYJV  
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private void processErrorCode(int nErrorCode) -9s&OKo`({  
{ F)S?>P&  
System.err.println("Error Code : " + nErrorCode); g\aq#QV  
} xR&Le/3+  
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//停止文件下载 P4s,N|bs`  
public void siteStop() TLz>|gr  
{ _o>?\:A  
bStop = true; #!4 HSBf  
for(int i=0;i<nStartPos.length;i++) 'W~6-c9y  
fileSplitterFetch.splitterStop(); KM-7w66V  
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} [>:9
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} #ePtfRzJ  
//负责部分文件的抓取 dp'k$el  
**FileSplitterFetch.java Z.U8d(  
*/ Cs^'g'  
package NetFox; j$z!kd+%  
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import java.io.*; 1X#gHstD  
import java.net.*; qu/b:P  
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public class FileSplitterFetch extends Thread { XhJYsq]]J  
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String sURL; //File URL wD $sKd  
long nStartPos; //File Snippet Start Position [4\n(/  
long nEndPos; //File Snippet End Position l}9E0^AS  
int nThreadID; //Thread's ID |6Qn/N$+f  
boolean bDownOver = false; //Downing is over \7*"M y*  
boolean bStop = false; //Stop identical Q^oB`)k  
FileAccessI fileAccessI = null; //File Access interface JcW<<7R  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException JS(%:  
{
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this.sURL = sURL; zdN(r<m9"  
this.nStartPos = nStart; e]3b0`E  
this.nEndPos = nEnd; %j;mDR95  
nThreadID = id; 3TNj*jo  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 OF1Qr bj  
} [?VkwFD0  
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public void run() Q=F4ZrNqD  
{ 7\EY&KI"0  
while(nStartPos < nEndPos && !bStop) (aSY.#;  
{ ,<]~/5-f  
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try{ n]v,cfn/=<  
URL url = new URL(sURL);  sf'+;  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Qjd<%!]+\  
httpConnection.setRequestProperty("User-Agent","NetFox"); URDXyAt  
String sProperty = "bytes="+nStartPos+"-"; ]E}eM@xdD  
httpConnection.setRequestProperty("RANGE",sProperty);  [?moS!  
Utility.log(sProperty); YG#.L}X@C  
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InputStream input = httpConnection.getInputStream(); G q2@37
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//logResponseHead(httpConnection); P] qL&_  
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byte[] b = new byte[1024]; 1'BC R  
int nRead; jLF,R7t  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) e>!=)6[*  
{ 9<-7AN}Z  
nStartPos += fileAccessI.write(b,0,nRead); a0 8Wt  
//if(nThreadID == 1) dNT
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); +$\/HO  
} XywsjeI4  
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3\0,>L9ET@  
Utility.log("Thread " + nThreadID + " is over!"); )^LiALh  
bDownOver = true; 4LkW`Sbm  
//nPos = fileAccessI.write (b,0,nRead); bDT@E,cSi  
} %v,a3^Qu  
catch(Exception e){e.printStackTrace ();} #Mrc!pT]xy  
} b+e9Pi*\  
} #B!<gA$/  
1Y(NxC0P=g  
F8d:7`lO@/  
//打印回应的头信息 `xF^9;5mi  
public void logResponseHead(HttpURLConnection con) V[ 'lB.&t  
{ l$g \t]  
for(int i=1;;i++) ND\M  
{ U~q2j#pJ  
String header=con.getHeaderFieldKey(i); H_d^Xk QZ  
if(header!=null) '))K' u  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); D/bF  
Utility.log(header+" : "+con.getHeaderField(header)); 4{CeV7  
else HJt@m &H|  
break; 't3&,:Y  
} OZ6:u^OS]  
} G?<uw RV  
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public void splitterStop() (qDPGd*1  
{ T$*#q('1"}  
bStop = true; eNu]K,rT  
} sny$[!)  
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} {iYrC m[_  
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/* W?<<al*  
**FileAccess.java ,Rdw]O  
*//文件访问(定位，写) @wcrtf~{)&  
package NetFox; l-$5CO  
import java.io.*; W:
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public class FileAccessI implements Serializable{ G.]'pn  
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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 .~X&BY>qP  
RandomAccessFile oSavedFile; u4|)A4n  
long nPos; OM?FpRVU8  
)3.=)?XW  
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public FileAccessI() throws IOException epgAfx-_OH  
{ rqz48~\lJ  
this("",0); W/<Lp+p  
} c!N#nt_<  
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public FileAccessI(String sName,long nPos) throws IOException GD%qrK?  
{ Qt>Bvu Q  
oSavedFile = new RandomAccessFile(sName,"rw"); BvP++,a&Sa  
this.nPos = nPos; CbFO9q  
oSavedFile.seek(nPos); hWi2S!*Y  
} }kSP p  
F},kfCFF  
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public synchronized int write(byte[] b,int nStart,int nLen) |

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{ gts09{"}Y  
int n = -1; b9VI(s>  
try{ N ;Cs? C  
oSavedFile.write(b,nStart,nLen); ?(M$r\\  
n = nLen; d2fiPI7lg  
} eOahr
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catch(IOException e) lib}dk  
{ Q5]rc`} 5  
e.printStackTrace (); *onVG5<  
} mQ3gp&d3W  
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,/Q`gRBh"  
return n; I#;.;%u  
} 2V*;=cv~z  
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} =.l>Uw!  
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/* 5a4i)I63o  
**SiteInfoBean.java zXk^ugFy  
*/
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package NetFox; E
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public class SiteInfoBean { $`P]%I}  
8! /ue.T  
BZIU@^Q_Y[  
private String sSiteURL; //Site's URL &{q<  
private String sFilePath; //Saved File's Path _Td#C1g3  
private String sFileName; //Saved File's Name KN&|&51p}  
private int nSplitter; //Count of Splited Downloading File -s\R2_(  
N*\ri0  
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public SiteInfoBean() )1 QOA  
{//nSplitter的缺省值为5 93
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//default value of nSplitter is 5 ,;Uf>8~  
this("","","",5); x6ayFq=  
} GyVuQ51  
Df$~=A}  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) (M{>9rk8  
{ TaF;PGjVw  
sSiteURL= sURL; Oz
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sFilePath = sPath; yqR]9"a  
sFileName = sName; NC iBn>=:  
this.nSplitter = nSpiltter; 7~;)N$d\  
>CwI(vXn  
2B
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} xNa66A-8  
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public String getSSiteURL() e [6F }."c  
{ (Ffa{Tt!  
return sSiteURL; ;P$ _:-C  
} _xBhMu2f  
[+="I &  
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public void setSSiteURL(String value) BqDsf5}jpA  
{ 0uIBaW3
s  
sSiteURL = value; Fc=6*.hy  
} SR_-wD  
?b93! Q1  
KHGUR(\Rd6  
public String getSFilePath()
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{ -B(p8YH  
return sFilePath; HrMbp  
} \j &&o  
>/NegJh'F}  
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public void setSFilePath(String value) l3/Cj^o
4  
{ P% 8U  
sFilePath = value; }J2f$l>R  
} -Owb@
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[nlq(DGJhp  
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public String getSFileName() 7#X`D  
{ .F[5{XV  
return sFileName; k_?~@G[I  
} h cu\c+
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5+j):_  
3(gOF&Uf9  
public void setSFileName(String value) .[1@wW&L  
{ ZwiXeD+4  
sFileName = value; 1]vDM&9  
} sGpAaGY>  
S,f#g?V  
.q!
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public int getNSplitter() UPPlm\wb*  
{ B}K<L\S  
return nSplitter; %?F$3YN,  
} _lRIS_^;eE  
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t**d{P+  
public void setNSplitter(int nCount) Y"nz l]T  
{ 5KIhk`S  
nSplitter = nCount; dxH.  
} !1A< jL  
} =}Q|#C  
{<#b@=G  
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/* KP$AT}D  
**Utility.java j0w@ \gO<  
*/ :@@m'zF<;  
package NetFox; ic l]H  
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public class Utility { .'h^  
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&5G@YQD1e  
public Utility() 'Z%1Ly^b  
{ $@L2zl1  
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H]f[r~  
} Y^;izM}  
$Zkk14  
//线程睡眠 6Tc!=lk  
public static void sleep(int nSecond) e@/' o/  
{ CC3M7|eO3  
try{ p _3xW{I  
Thread.sleep(nSecond);  5PC:4  
} SUW=-M  
catch(Exception e) x"cB8bZ!$  
{ @Pi]kWW})  
e.printStackTrace (); IS;[oJef  
} oTcf[<  
} <(V~eo e  
6s ~!B{Q  
//日志 4gWlSm)  
public static void log(String sMsg) @ `mke4>_  
{ <
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System.err.println(sMsg); \w(0k^<7  
} /Ei e5p  
BQ70<m2D$  
Q&"oh  
public static void log(int sMsg) (hIo0.  
{ -
})zRL0!'  
System.err.println(sMsg);  C?'s  
} iun_z$I<+Z  
}  !$!%era`  
|Q";a:&$  
A4b+:MQ*OX  
/* w*o2lg9  
**TestMethod.java v\?l+-A?y  
*/ rls{~ZRl  
package NetFox; {y%@1q%"  
vg_PMy\  
NLxR6O4}8  
public class TestMethod { v-Q>I5D;:  
rq}xuSFI  
AEElaq.B  
public TestMethod() U)Tl<l<  
{ ///xx/weblogic60b2_win.exe 0[N1SY\lj  
try{ .C ,dV7  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); !T8sWMY  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ZA@zs,o%  
SiteFileFetch fileFetch = new SiteFileFetch(bean);
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fileFetch.start(); jR@>~t[}o  
} 'm-5  
catch(Exception e){e.printStackTrace ();} Uty0mc(  
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h]&~yuI>  
} t}OzF cyqN  
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public static void main(String[] args) R|U
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{ y-gXGvZ  
new TestMethod(); /WK1(B:  
} RUVrX`u*(  
} Neii$  
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