http断点续传简单实现（java)

/* &}b-aAt  
**SiteFileFetch.java d6g^>}-!t  
*/ 8'VcaU7Nh  
package NetFox; KqWt4{\8v`  
import java.io.*; FrQRHbp3  
import java.net.*; 7HEUmKb"  
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public class SiteFileFetch extends Thread { z5IdYF?  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Mzj|57:gx  
long[] nStartPos; //开始位置 gP>`DPgb^  
long[] nEndPos; //结束位置 Yi#U~ h  
FileSplitterFetch[] fileSplitterFetch; //子线程对象
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long nFileLength; //文件长度 oTxE]a,  
boolean bFirst = true; //是否第一次取文件 -i"?2gK  
boolean bStop = false; //停止标志 ~cW,B}  
File tmpFile; //文件下载的临时信息 nrRP1`!]T  
DataOutputStream output; //输出到文件的输出流 c>yqq'  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） +jGSD@32>  
public SiteFileFetch(SiteInfoBean bean) throws IOException sB%QqFRP  
{ pcO0xrI  
siteInfoBean = bean; T8-,t];i  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); SR
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); x10u?@  
if(tmpFile.exists ()) [BKX$A:Y  
{ {K>}eO:K  
bFirst = false; 3YJa3fflK  
read_nPos(); b&E9xD/;r  
} \"?5CHz*  
else y-^m  
{ hScC<=W  
nStartPos = new long[bean.getNSplitter()]; )~H&YINhn  
nEndPos = new long[bean.getNSplitter()]; %g{<EuK]p  
} xjg(}w  
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} kr>H,%3~  
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public void run() Eao^/MKx-  
{ TjLW<D(i>  
//获得文件长度 U@<]>.$  
//分割文件 < r7s,][&  
//实例FileSplitterFetch ?'+kZ|  
//启动FileSplitterFetch线程 z"j]m_mH  
//等待子线程返回 u#~q86k  
try{ xmBGZ4f%  
if(bFirst) n(?BZ'&!O  
{ s\3OqJo%)  
nFileLength = getFileSize(); !pAb+6~T  
if(nFileLength == -1) &_W~d0  
{ ,AEaW  
System.err.println("File Length is not known!"); ?Oyps7hXx  
} M sQ>eSk
 
else if(nFileLength == -2) \ICc?8oL  
{ o%sx(g=q6  
System.err.println("File is not access!"); Z,}c)  
} %+0V0.  
else Dwuao`~Xm  
{ }`^DO Ar  
for(int i=0;i<nStartPos.length;i++) X&s"}Hf  
{ \zM3{{mV/  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); l7vxTj@(-  
} VL2+"<  
for(int i=0;i<nEndPos.length-1;i++) G
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{ %E*Q0/  
nEndPos = nStartPos[i+1]; Zj5B}[,l\  
} c4Wl^E8  
nEndPos[nEndPos.length-1] = nFileLength; M" R=;n  
} \k>1q/T0V  
} jU0E=;1  
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/
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//启动子线程 C q)Cwc[H  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; (L'|n*Cr  
for(int i=0;i<nStartPos.length;i++) g#b9xTGJ^  
{ 0I['UL^!F  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #b
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), r<c&;*  
nStartPos,nEndPos,i); vtF|:
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); E(g$f.9  
fileSplitterFetch.start(); iOJ5KXrAO  
} NE4 }!I  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); EFn[[<&><t  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Jp"yb`w  
nEndPos = " + nFileLength); XJe}^k  
// fileSplitterFetch[nPos.length-1].start(); }*?,&9/_)  
+=K =B  
nZ %%{#T7  
//等待子线程结束 _"[Ls?tRX  
//int count = 0; $0XR<D  
//是否结束while循环 bCqTubbx!t  
boolean breakWhile = false; d<Dm(  
J#xZ.6)  
l
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while(!bStop) XNJ3.w:R  
{ Y49&EQ  
write_nPos(); ?azcWf z0  
Utility.sleep(500); Y.kgJ #2  
breakWhile = true; qL4s@<|~  
n?*r,)'  
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for(int i=0;i<nStartPos.length;i++) 1pAcaJzf  
{ A DVUx}  
if(!fileSplitterFetch.bDownOver) 9,[Af
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{ h@PE:=  
breakWhile = false; 7n,=`0{r  
break; {mUt|m7!  
} XAZPbvG|$  
} ![9$ru  
if(breakWhile) cx]H8]ch7  
break; 0D Lw  
dhjX[7Bl9  
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//count++; zx5#eMD  
//if(count>4) lffw "  
// siteStop();  &Ufp8[  
} Y#QXvo%  
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System.err.println("文件下载结束！"); ST2:&xH(  
} O?ODfO+>  
catch(Exception e){e.printStackTrace ();} bgxk:$E
 
} 67XUhnE  
/>N#PF  
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//获得文件长度 .yDGwLry  
public long getFileSize() e_"m\e#N  
{ zhJ0to[%?  
int nFileLength = -1; k*v${1&  
try{ AGm=0Om  
URL url = new URL(siteInfoBean.getSSiteURL()); UVXSW*$  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); S*gm[ZLQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); N\];{pe>  
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int responseCode=httpConnection.getResponseCode(); C1+f\A|9FP  
if(responseCode>=400) cUr!U\X[  
{ g)R2V  
processErrorCode(responseCode); &Q#*Nnb3  
return -2; //-2 represent access is error &>B"/z  
} @meT8S9t  
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String sHeader; M>[
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for(int i=1;;i++) reNf?7G+m  
{ c#>(8#'.U  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); .#-F@0a  
//Utility.log(in.readLine()); 46pR!k  
sHeader=httpConnection.getHeaderFieldKey(i); q2s
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if(sHeader!=null) "l9aBBiu  
{ -- FzRO{D  
if(sHeader.equals("Content-Length")) e0h[(3bXs$  
{ )UM^#<-  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); [8^q3o7n  
break; tv.<pP9-C  
} jz![#-G  
} 92t.@!m`  
else b,YNCb]H  
break; ruGeN  
} $xbW*w  
} (wM` LE(Ks  
catch(IOException e){e.printStackTrace ();} pA8As  
catch(Exception e){e.printStackTrace ();} v&'#Gg  
Y*PfU+y~  
/KX+'@  
Utility.log(nFileLength); /1v9U|j  
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return nFileLength; $\Y&2&
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} P3
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Pv/v=s>X  

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//保存下载信息（文件指针位置） 4$[o;t>  
private void write_nPos() n\l?+)S *  
{ @$T$hMl  
try{ CpmT*  
output = new DataOutputStream(new FileOutputStream(tmpFile)); _OTVQo Ap  
output.writeInt(nStartPos.length); #$-E5R;x  
for(int i=0;i<nStartPos.length;i++) %:d7Ts&?Z  
{ #aU!f"SS  
// output.writeLong(nPos); +q'1P}e  
output.writeLong(fileSplitterFetch.nStartPos); 5EcVW|(  
output.writeLong(fileSplitterFetch.nEndPos); [i/!o
vcY  
} gK`w|kh`  
output.close(); ur\6~'l4  
} rBNVI;JZW  
catch(IOException e){e.printStackTrace ();} v/q-{1  
catch(Exception e){e.printStackTrace ();} 5tQz!M  
} <[cpaZT,  
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(Z(S
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//读取保存的下载信息（文件指针位置） {h7 vJ^  
private void read_nPos() 31a,i2Q4  
{ 0_gN]>,9n  
try{ >8"Svt$  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); q[a\a7U z  
int nCount = input.readInt(); oCaYmi=:  
nStartPos = new long[nCount]; w}>%E6UY  
nEndPos = new long[nCount]; j#n ]q{s4  
for(int i=0;i<nStartPos.length;i++) _|#abLh%  
{ k.ou$mIY  
nStartPos = input.readLong(); FOsd{Fw  
nEndPos = input.readLong(); nc k/Dw  
} sv%X8  
input.close(); `Npa/Q  
} _xaum  
catch(IOException e){e.printStackTrace ();} {Ya$Q#l  
catch(Exception e){e.printStackTrace ();} K=[7<b,:3  
} cERIj0~  
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private void processErrorCode(int nErrorCode) z4:!*:.Asu  
{ ltNCti{Q  
System.err.println("Error Code : " + nErrorCode); l/'GbuECm  
} wf\"&xwh?  
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x|~8?i$%  
//停止文件下载 N>H@vt~  
public void siteStop() 4^L;]v,|7  
{ u /F!8#  
bStop = true; k4K. mlIO  
for(int i=0;i<nStartPos.length;i++) F] c\Qt  
fileSplitterFetch.splitterStop(); X
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} q`c!!Lg  
} ; j!dbT~5  
//负责部分文件的抓取 hu}$\  
**FileSplitterFetch.java el9P@r0  
*/ E)_n?>Ar  
package NetFox; g-sNYd%?a  
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import java.io.*; O+}py{ st  
import java.net.*; 8_('[89m  
+ `|A/w  
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public class FileSplitterFetch extends Thread { &>JP.//spi  

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String sURL; //File URL H9*k(lnz`  
long nStartPos; //File Snippet Start Position \?xM%(:<Q  
long nEndPos; //File Snippet End Position r].n=455[  
int nThreadID; //Thread's ID f$C{Z9_SX  
boolean bDownOver = false; //Downing is over xe!bfzU  
boolean bStop = false; //Stop identical :wC\IwG~CE  
FileAccessI fileAccessI = null; //File Access interface 7iP+!e}$.  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException e|]e\Or>  
{ W8d-4')|  
this.sURL = sURL; +S4n416K  
this.nStartPos = nStart; i>Q!5  
this.nEndPos = nEnd; h=#w< @  
nThreadID = id; :ppaq  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 hq=;ZI  
} E-z5mX.2  
:$k*y%Z*N&  
AP&//b,^M  
public void run() *[[Gu^t^!  
{ t(z]4y  
while(nStartPos < nEndPos && !bStop) y:;.r:  
{ AF'<  
:?Ns>#6t  
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try{ f^F;`;z  
URL url = new URL(sURL); 981-[ga`Y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); hXTfmFy{n  
httpConnection.setRequestProperty("User-Agent","NetFox"); F3|^b{'zO  
String sProperty = "bytes="+nStartPos+"-"; jK w 96  
httpConnection.setRequestProperty("RANGE",sProperty); 6w^P{%ul  
Utility.log(sProperty); `
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InputStream input = httpConnection.getInputStream(); _Sr}3  
//logResponseHead(httpConnection); Kip&YB%rk  
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byte[] b = new byte[1024]; p@tg pFt  
int nRead; vIV|y>;g  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) u$T]A8e  
{ )3h\QE!z  
nStartPos += fileAccessI.write(b,0,nRead); &;@L] o  
//if(nThreadID == 1) <],{at` v  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); $k~TVm Yex  
} JK/{IkF  
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:&BPKqKp  
Utility.log("Thread " + nThreadID + " is over!"); &L8RLSfX  
bDownOver = true; s=8H<'l  
//nPos = fileAccessI.write (b,0,nRead); D3o,2E(o  
} x%mRDm~-  
catch(Exception e){e.printStackTrace ();} (?4%Xtul1  
} M$K%e  
} V*?c
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6 >kULp  
//打印回应的头信息 ZM<6yj"f  
public void logResponseHead(HttpURLConnection con) aXe&c^AR  
{ hr vTFJ  
for(int i=1;;i++) &N}"4  
{ MPB[~#:  
String header=con.getHeaderFieldKey(i); }1#m+ (;  
if(header!=null) }_+XN"}C  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); *6}M.`.-  
Utility.log(header+" : "+con.getHeaderField(header)); R$&;  
else ob7'''i  
break; e;.,x
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} Ks.b).fH  
} p(F@lL-  
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public void splitterStop() #T)Gkc"{  
{ o
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bStop = true; OUulG16kK  
} ASXGM0t  
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} XCM!8x?K  
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%1#\LRA(  
/* kz=ho~ @  
**FileAccess.java T~UDD3  
*//文件访问(定位，写) )LP'
4*  
package NetFox; j^jC|  
import java.io.*; d@3
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=3(v4E':5  
public class FileAccessI implements Serializable{
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 _T)y5/[  
RandomAccessFile oSavedFile; S#ryEgc]  
long nPos; ,M.C]6YMr  
2}^=NUM\NX  
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public FileAccessI() throws IOException *R6lK&  
{ P& 1$SWNyW  
this("",0); D`XXR}8V  
} zgjg#|  
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public FileAccessI(String sName,long nPos) throws IOException gJ l^K  
{ INndTF  
oSavedFile = new RandomAccessFile(sName,"rw"); 19fa7E<  
this.nPos = nPos; [Qs`@u<%  
oSavedFile.seek(nPos); =z}PR1X!  
} $:u*)&"t|  
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public synchronized int write(byte[] b,int nStart,int nLen) #IH9S5B [  
{ x(c+~4:_M  
int n = -1; Ug*B[q/  
try{ 21!X[)r  
oSavedFile.write(b,nStart,nLen); NVzo)C8kb  
n = nLen; EC,,l'%a|/  
} _`gF%
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catch(IOException e) QN8+Uj/zx  
{ 4j3q69TZR  
e.printStackTrace (); e"
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} 2*snMA  
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return n; (H:c80/V  
} C2<TR PT  
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} ];5J  
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/* /J^dzvH  
**SiteInfoBean.java EI=~*&t  
*/ 7fqQ  
package NetFox; pnu?=.O  
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public class SiteInfoBean { Sk EI51]  
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private String sSiteURL; //Site's URL 8K2@[TE=5  
private String sFilePath; //Saved File's Path W9l](Ow  
private String sFileName; //Saved File's Name 9{(q[C5m  
private int nSplitter; //Count of Splited Downloading File zgFL/a<  
9ug4p']  
((Av3{05H&  
public SiteInfoBean() ]$#bNt/p  
{//nSplitter的缺省值为5 Dt!KgI3  
//default value of nSplitter is 5 
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this("","","",5); KxErWP%  
} :PV3J0pB~  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) T}J)n5U}\  
{ wYe;xk`>  
sSiteURL= sURL; !{,2uQXe  
sFilePath = sPath; gIO_mJ3 u  
sFileName = sName; !>'A2V~F  
this.nSplitter = nSpiltter; $<nD-4p  
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e 6wevK\  
} 8'E7Uj  
`
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public String getSSiteURL() -5v{p  
{ aAqM)T83  
return sSiteURL; E4=D$hfq`  
} Cn=#oE8
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Tcv/EST  
public void setSSiteURL(String value) ]Ky`AG`2~  
{ #"oLz"{  
sSiteURL = value; ,2
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} 3ut<o-
 
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public String getSFilePath() +P+h$gQ  
{ mS}.?[d"  
return sFilePath; L{1[:a)']B  
} Vo[.^0  
8B+C[Q:+'  
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public void setSFilePath(String value) w_"-rGV  
{ V:t{mu5j  
sFilePath = value; ]):>9q$C  
} d" 0&=/  
*
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public String getSFileName() 'ahz@+lO  
{ T+gH38!e  
return sFileName; 89KFZ[.}]  
} -ert42fN  
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public void setSFileName(String value) *6][[)(  
{ ~Hd*Xl  
sFileName = value; 4Q1R:Ra  
} }Q9+krrow  
yW*,Llb5  
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public int getNSplitter() 1Ke9H!_P  
{ sUQ Q/F6  
return nSplitter; 7/KK}\NE  
} ' Qlj"U  
;jQ^8S  
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public void setNSplitter(int nCount) > Xij+tt{  
{ .=yv m  
nSplitter = nCount; ~
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} BaUuDo/ZO  
} NYKYj`K  
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p<mBC2!%  
/* Gr}NgyT<!D  
**Utility.java Wwr  
*/ zmu+un"\j  
package NetFox; ] M#LB&Pe  
xh#pw2v7V  
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public class Utility { _KT'W!7  
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public Utility() 6f t6;*,  
{ E{^W-  
+~P_o_M  
tv~Y5e&8  
} #Jp|Cb<qx  
+!:=Mm  
//线程睡眠 c/j+aj0.v  
public static void sleep(int nSecond) Q`;eI a6U  
{ @)!N{x?  
try{ D dCcsYm,  
Thread.sleep(nSecond); [~G1Rz\h  
} BG.s
HI{  
catch(Exception e) ^ uwth  
{ LCzeE7x  
e.printStackTrace (); .RAyi>\e  
} 3^$=XrD  
} > sQ&5-i  
,&fZo9J9  
//日志 s%>8y\MaK  
public static void log(String sMsg) 1{a4zGE?[  
{ 4M6[5RAW{  
System.err.println(sMsg); Y" rODk1  
} ;kR=vv  
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public static void log(int sMsg) \}Iq-Je   
{ %""h:1/S  
System.err.println(sMsg); 4gVIuF*pS  
} h^1!8oOYD  
} >p;&AaXkoG  
&RI;!qn6(  
=*zde0T?l  
/* $"MVr5q6  
**TestMethod.java _V0%JE'  
*/ .Y8P6_  
package NetFox; ?Pf#~U_  
Je2&7uR0  
-xN/H,xok  
public class TestMethod { Xh3b=i|K  
d+ZXi'  
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public TestMethod() AGjjhbGB  
{ ///xx/weblogic60b2_win.exe $<
&_9T#&w  
try{ \i}-Y[Dg  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 2+C:Em0yI  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); q"DHMZB  
SiteFileFetch fileFetch = new SiteFileFetch(bean); W2zG"Q  
fileFetch.start(); D`'Cnt/  
} MA}}w&  
catch(Exception e){e.printStackTrace ();} rl$"~/ oz  
"68X+!  
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} h+Yd \k  
~Eb:AC5  
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public static void main(String[] args) lFSvHs5  
{ 1w7XM0SHcn  
new TestMethod(); `g)  
} ".N{v1  
} BSB&zp  
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