http断点续传简单实现（java)

/* 7AFS)_w  
**SiteFileFetch.java TF iM[  
*/ e7)%=F/)  
package NetFox; ?3E_KGI  
import java.io.*; 1p"EE~v  
import java.net.*; nluyE
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public class SiteFileFetch extends Thread { Pk?%PB?Z  
; K 6Fe)  
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SiteInfoBean siteInfoBean = null; //文件信息Bean meVVRFQ2+  
long[] nStartPos; //开始位置 !O-_
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long[] nEndPos; //结束位置 6+f>XL#w  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 <[B[  
long nFileLength; //文件长度 SAxa7B/U2  
boolean bFirst = true; //是否第一次取文件 8KELN(o$ 7  
boolean bStop = false; //停止标志 Wj{Rp{}3  
File tmpFile; //文件下载的临时信息
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DataOutputStream output; //输出到文件的输出流 !7a^8   
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） o_KcnVQ\  
public SiteFileFetch(SiteInfoBean bean) throws IOException W<hdb!bE  
{ dK(%u9v  
siteInfoBean = bean; n#L2cv~Aj"  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); $^D(%  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); zam0(^=  
if(tmpFile.exists ()) *Wo$$T  
{ !m:PBl5  
bFirst = false; "M#`y!__  
read_nPos(); LsD9hb7  
} #vZ]2Ud=2  
else ~TK^aM   
{ {Ljl4Sp&  
nStartPos = new long[bean.getNSplitter()]; OVo  
nEndPos = new long[bean.getNSplitter()]; P;
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} I%b:Z  
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} >,]e[/p  
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public void run() MdboWE5i  
{ l )V43  
//获得文件长度 /ZN5WK  
//分割文件 F$yFR  
//实例FileSplitterFetch c&?H8G)x  
//启动FileSplitterFetch线程 ao5yW;^y  
//等待子线程返回 :yFCp@&  
try{ ./*,Thc  
if(bFirst) _,1kcDu  
{  (mD:[|.  
nFileLength = getFileSize(); x<7` 109]  
if(nFileLength == -1) 2DqHqq9m  
{ %f(.OR)6{  
System.err.println("File Length is not known!");
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} 9@*>$6  
else if(nFileLength == -2) }`FC
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{ k*6eZ7  
System.err.println("File is not access!"); b/}0 &VXo  
} qa`(,iN  
else <).qe Z  
{ fTtSx_}3H  
for(int i=0;i<nStartPos.length;i++) #UeU:RJ1  
{ lc(iy:
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); +~.Jw#HqS  
} !e"m*S.(6{  
for(int i=0;i<nEndPos.length-1;i++) ]_xGVwem  
{ QD VA*6F  
nEndPos = nStartPos[i+1]; .Tqvy)'  
} &L`p4AZ  
nEndPos[nEndPos.length-1] = nFileLength; gCI'YEx  
} +Z(VWu6  
} M +q7h+HP  
19`0)pzZ*P  
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//启动子线程 \eN/fTPm  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 1c~#]6[  
for(int i=0;i<nStartPos.length;i++) <$6E r  
{ I _G;;GF  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), F>R)~;Ja  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), E?o8'r  
nStartPos,nEndPos,i); 6x8|v7cMH  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); T )]|o+G  
fileSplitterFetch.start(); ,IATJs$E  
} o[6"XJ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,dMi+c`
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); =B%e0M  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ZWEzL$VWi  
nEndPos = " + nFileLength); !Shh$iz  
// fileSplitterFetch[nPos.length-1].start(); t4f\0`jN  
iiB$<b.((I  
;H|M)z#[Z  
//等待子线程结束 M)Q+_c2*  
//int count = 0; #TF  
//是否结束while循环 UbH=W(%  
boolean breakWhile = false; UeQ%(f  
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while(!bStop) #+nv,?@  
{
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write_nPos(); +=$G6uR$  
Utility.sleep(500); DO{4n1-U  
breakWhile = true; P .(X]+  
2 G{KpM&  
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for(int i=0;i<nStartPos.length;i++) syvi/6  
{ ,r4af<  
if(!fileSplitterFetch.bDownOver) xbA2R4|  
{ \C|06Bs$  
breakWhile = false; mJT m/C  
break; 4{E=wg^p  
} mj~CCokF{?  
} (#k#0T kE  
if(breakWhile) }qPo%T  
break; fsu"Lc  
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//count++; S0yT%V  
//if(count>4) (FHh,y~v  
// siteStop(); Q5JeL6t  
} krU2S-  
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System.err.println("文件下载结束！"); ^\%%9jY  
} s#3{c@^3  
catch(Exception e){e.printStackTrace ();} o 8U2vMH  
} K.~U%v}  
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//获得文件长度 Ja1*a,],L  
public long getFileSize() B%/Pn 2  
{ !$HWUxM;p  
int nFileLength = -1; ?hYe4tc-#  
try{ Z(P#]jI]  
URL url = new URL(siteInfoBean.getSSiteURL()); Xqk$[peS  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); G <q@K-  
httpConnection.setRequestProperty("User-Agent","NetFox"); =%p{"<  
K(^x)w r-:  
@@QU"8q  
int responseCode=httpConnection.getResponseCode(); 0a5P@;"a  
if(responseCode>=400) ;z#9>99rH  
{ [A47OR  
processErrorCode(responseCode); x4K
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return -2; //-2 represent access is error &~8}y+z  
} F)G#\r  
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String sHeader; Z:Wix|,ONS  
~A)$="  
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for(int i=1;;i++) {)M4h?.2  
{ %j,Ny}a  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ~Y(M>u.+!  
//Utility.log(in.readLine()); x?kZD~|{)  
sHeader=httpConnection.getHeaderFieldKey(i); }|d:(*  
if(sHeader!=null) ;S7xJ'H  
{ )Jc>l;G(M  
if(sHeader.equals("Content-Length")) E9i WGSE  
{ q%"nk  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); TJ<PT  
break; \r2w@F{C  
}  >Pu*MD;  
} bu.36\78  
else `e bB+gI  
break; {:Q2Itsy  
} =YBJ7.Y  
} 8Xr3q eh+  
catch(IOException e){e.printStackTrace ();} d3\8BKp  
catch(Exception e){e.printStackTrace ();} I4hr5M3  
ch&r.  
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Utility.log(nFileLength); ^V:YNUqp#  
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return nFileLength; >dM
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} Pzqgg43Xf  
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buoz La  
//保存下载信息（文件指针位置） ;9~z_orNQZ  
private void write_nPos() #O~Y[''C5X  
{ e#seqx  
try{ 5*CwQJC<  
output = new DataOutputStream(new FileOutputStream(tmpFile)); l*eA ?Qz  
output.writeInt(nStartPos.length); ;(sb^O  
for(int i=0;i<nStartPos.length;i++) #yqcUbJY0R  
{ WM#!X!Vo  
// output.writeLong(nPos); 2#R"#Q!  
output.writeLong(fileSplitterFetch.nStartPos); bhI8b/  
output.writeLong(fileSplitterFetch.nEndPos); I}:/v$btM  
} ;#+#W+0  
output.close(); g (~&  
} <[q)2 5RL  
catch(IOException e){e.printStackTrace ();} aZ'p:9e  
catch(Exception e){e.printStackTrace ();} oH;Y}h  
} $qvNv[  
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ql8:s>1T  
//读取保存的下载信息（文件指针位置） * n[6H  
private void read_nPos() +X< Z 43  
{ o 2DnkzpJ  
try{ q<1@ut  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 1^,rS  
int nCount = input.readInt(); q"Xls(  
nStartPos = new long[nCount]; /; _"A)0  
nEndPos = new long[nCount]; BP7_o63/G  
for(int i=0;i<nStartPos.length;i++) HG^8&uh]  
{ >3ODqRu  
nStartPos = input.readLong(); N&n{R8=^"  
nEndPos = input.readLong(); ^mGTZxO  
} +,%x&L&I  
input.close(); q\~7z1   
} ?]})Xf.A  
catch(IOException e){e.printStackTrace ();} B
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catch(Exception e){e.printStackTrace ();} Q=dR[t>^  
} ;9^B# aTM  
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private void processErrorCode(int nErrorCode) * T-XslI  
{ UKzmR
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System.err.println("Error Code : " + nErrorCode); iCHZ{<k  
} l"-D@]"  
n;MoMGnPh,  
iU3co|q7  
//停止文件下载 GY!&H"%  
public void siteStop() {S}/LSNB  
{ -uh/W=Q1R  
bStop = true; LvR=uD  
for(int i=0;i<nStartPos.length;i++) -H]svOX  
fileSplitterFetch.splitterStop(); rF5<x3  
(R0  
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} Wbc %G8  
} %=|I;kI?  
//负责部分文件的抓取 !ine|NM  
**FileSplitterFetch.java > {:8c-\2}  
*/ d BJM?/  
package NetFox; A*$vk
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import java.io.*; TKm
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import java.net.*; {!,+C0  
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public class FileSplitterFetch extends Thread { >s{[d$  
 l[ L{m7  
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String sURL; //File URL 20J
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long nStartPos; //File Snippet Start Position gDA hl  
long nEndPos; //File Snippet End Position co;2s-X  
int nThreadID; //Thread's ID ch-GmAj 9  
boolean bDownOver = false; //Downing is over Qdtfi1_Y1  
boolean bStop = false; //Stop identical x|Q6[Y  
FileAccessI fileAccessI = null; //File Access interface ld3,)ZY  
=]D##R  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException f",B;C  
{ rVz#;d!`z  
this.sURL = sURL; M+ H$Jjcs  
this.nStartPos = nStart; NSxDCTw  
this.nEndPos = nEnd; Z,
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nThreadID = id; d+/d)cu  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 I5-/KVWb  
} q k!Q2W  
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public void run() yJr'\(  
{ f'}23\>  
while(nStartPos < nEndPos && !bStop) s(zG.7*3n  
{ )2R:P`U
 
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try{ +pDuRr  
URL url = new URL(sURL); ;KnnAZJ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wD*_S}]  
httpConnection.setRequestProperty("User-Agent","NetFox"); 7=JiL=  
String sProperty = "bytes="+nStartPos+"-"; 1W;+hXx  
httpConnection.setRequestProperty("RANGE",sProperty); vuD tEz  
Utility.log(sProperty); ;8UNM  

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InputStream input = httpConnection.getInputStream(); Vls*fY:W  
//logResponseHead(httpConnection); 5~ jGF  
/Cwt4.5  
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byte[] b = new byte[1024]; =m:0#&t,*  
int nRead; '!Q[
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) =_TCtH  
{ 2p@S-Lp  
nStartPos += fileAccessI.write(b,0,nRead); |JrG?:n  
//if(nThreadID == 1) @!K)(B;A0b  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "4I`.$F%O(  
} {X8F4  
* \f(E#wa  
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Utility.log("Thread " + nThreadID + " is over!"); (3W
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bDownOver = true; y|c]r!A  
//nPos = fileAccessI.write (b,0,nRead); 3vmZB2QG  
} .(3B}}gB>  
catch(Exception e){e.printStackTrace ();} tz2`X V{  
} '|Cs!Zl  
} fU$zG"a_  
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U JY`P4(  
//打印回应的头信息 `y m^0x8  
public void logResponseHead(HttpURLConnection con) :h?Zg(l  
{ Nqy',N  
for(int i=1;;i++) z[V|W  
{ ]#_,?d  
String header=con.getHeaderFieldKey(i); C S+6!F]  
if(header!=null) :MpIx&  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); c7S<ex,  
Utility.log(header+" : "+con.getHeaderField(header)); N#Y4nllJ  
else 7@MV
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break; CShVJ:u+K\  
} `[7&tOvSk  
} %I[(`nb  
qH$G_R#)8B  
TRG
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public void splitterStop() )k=8.j4  
{ 'V .4Nhd  
bStop = true; ,Rz,[KI|  
} /6b(w=pk  
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} r(0I>|u  
U
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/* p
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**FileAccess.java tk2B\}6  
*//文件访问(定位，写) zZGPA j  
package NetFox; ^`Vt<DMT  
import java.io.*; {SJ=|L6  
{PWz:\oaD  
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public class FileAccessI implements Serializable{ !G Z2|~f9  
XLI'f$w&  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 +.mIC:9  
RandomAccessFile oSavedFile; A<QYW,:|  
long nPos; ~`u?|+*BO  
e*:[#LJ]C  
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public FileAccessI() throws IOException >{$;O  
{ m>jX4D7KZ  
this("",0); JPS L-j  
} [P`Q_L,+  
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public FileAccessI(String sName,long nPos) throws IOException lTDF5.aE  
{ Y6W3WPs(  
oSavedFile = new RandomAccessFile(sName,"rw"); cg}46)^<QH  
this.nPos = nPos; `LVXK|m+$  
oSavedFile.seek(nPos); KSc&6UVz^  
} *
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*<OWd'LI  
k;#$Oxa>t=  
public synchronized int write(byte[] b,int nStart,int nLen) 6WzE'0Nyr  
{ 2<qq[2  
int n = -1; gh['T,  
try{ [`yiD
>  
oSavedFile.write(b,nStart,nLen); ,iB)8Km@U  
n = nLen; Qf$0^$ "  
} kS[k*bN0  
catch(IOException e) 67~m9pk  
{ |Gzd|$%Oq  
e.printStackTrace (); )jn|+M  
} iEsI  
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return n; ~2S`y=*:  
} I,l%6oPa  
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} ghx8dX}  
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/* Cc1sZWvz  
**SiteInfoBean.java jcYI"f"~  
*/ N?p9h{DG  
package NetFox; C;OU2,c,T  
o%+KS5v!  
H2zd@l:R  
public class SiteInfoBean { (|I0C 'Ki  
\V7Hi\)  
~lzV=c$t  
private String sSiteURL; //Site's URL lF8B+  
private String sFilePath; //Saved File's Path }V ;PaX  
private String sFileName; //Saved File's Name q@8Rlc&  
private int nSplitter; //Count of Splited Downloading File [t: =%&B  
3r%I *  
\Nb6E&+  
public SiteInfoBean() ygd'Nh!@  
{//nSplitter的缺省值为5 /?9e{,\s  
//default value of nSplitter is 5 Yc"G="XP;  
this("","","",5); RIC'JLWQ  
} ^r(2 r  
/7h}_zs6  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) (=)+as"u9*  
{ ZBJ.dK?Ky|  
sSiteURL= sURL; IgLP=mqcWK  
sFilePath = sPath;
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sFileName = sName; z }R-J/xr2  
this.nSplitter = nSpiltter; VrQw;-rQ  
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} lh(A=hn"n  
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public String getSSiteURL() qV/"30,K  
{ AZI%KM[  
return sSiteURL; '"GdO;}&  
} s,]6Lri`\  
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!r.X.C  
public void setSSiteURL(String value) \7$m[h{l  
{ e@L+z  
sSiteURL = value; @ns2$(wkm@  
} v9x $`  
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public String getSFilePath() L((z;y>q|  
{ f$*M;|c1c/  
return sFilePath; `w[0q?}"`  
} uQ5NN*C=  
8{4I6;e-  
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public void setSFilePath(String value) 3P^eD:) w  
{ t=xO12Z  
sFilePath = value; I@pnZ-5  
} C/<fR:`c  
A;SRm<,  
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public String getSFileName() &EE6<-B-  
{ 0=t_a]+  
return sFileName; xDRK^nmC  
} uLe+1`Y5Ux  
Y
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sFC1PdSk4T  
public void setSFileName(String value) ,y:q]PR  
{ nITr
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sFileName = value; ]9R?2{"K  
} `zZ=#p/  
jM2gu~  
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public int getNSplitter() f>#\'+l'  
{ ]A<\d  
return nSplitter; UrN$nhH  
} j(va#f#  

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public void setNSplitter(int nCount) }9 qsPn  
{ 'G@Npp)&^  
nSplitter = nCount; G5TdAW  
} :d)@|SR1  
} lJ}G"RT
m  
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/3FC@?l w4  
/* NawnC!~ $  
**Utility.java zT!JHG
 
*/ ;,Lq*x2s  
package NetFox; P1TLH2)  
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public class Utility { &NHIX(b6  
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public Utility() bL swq  
{ =qIJXV  
xqbI~jV#  
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} 1G{$ B^ f  
]
=@>;yP)  
//线程睡眠 Xa9G;J$  
public static void sleep(int nSecond) xQWZk`6~L  
{ 2\EMtR>.M'  
try{ Fv#ToT:QXe  
Thread.sleep(nSecond); 9at7$Nq  
} N @]*E  
catch(Exception e) qC`"<R=GX  
{ s{<rc>  
e.printStackTrace (); b$.N8W%  
} 6j_ A{*~Ng  
} YBHmd  
|D`Zi>lv  
//日志 <<4G GO  
public static void log(String sMsg) `|v0@-'$  
{ ed>_=i  
System.err.println(sMsg); PJh\U1Z  
} }JrM!'  
;'2y6"\Y  
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z  
public static void log(int sMsg) f>Bcr9]]  
{ n'%*vdHKm  
System.err.println(sMsg); %Cb8vYz~  
} _%Mu{Ni&  
} w;r-TLf  
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3cQTl5,  
/* N#]f?6*R  
**TestMethod.java VY~WkSi[<  
*/ >N+e c_D^  
package NetFox; 6mMJ$FY+  
!=q {1\#  
\!z=x#!O$  
public class TestMethod { w#XE!8`  
P#rwYPww\  
K& 2p<\2  
public TestMethod() =NyzX&H6  
{ ///xx/weblogic60b2_win.exe q:1 1XPP  
try{ sR?_{rQ  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); IO]Oo3  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); >2>xr"  
SiteFileFetch fileFetch = new SiteFileFetch(bean); /KlA7MH6  
fileFetch.start(); p*NC nD*  
} +S0A`rL  
catch(Exception e){e.printStackTrace ();} -+Quw2465^  
@YW
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} uyjZmT/-  
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public static void main(String[] args) owYfrf3ZLX  
{ 8*6J\FE<p  
new TestMethod(); iWQBo>x  
} '{6`n5:e  
} q2gc.]K\  
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