http断点续传简单实现（java)

/* y*h1W4:^-  
**SiteFileFetch.java M5WtGIV  
*/ zL`uiZl  
package NetFox; `(/saq*  
import java.io.*; (0#F]""\e  
import java.net.*; =4<S8Cp  
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public class SiteFileFetch extends Thread { A]Tcj^#  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 4z%#ZIy3   
long[] nStartPos; //开始位置 rn:zKTyhw  
long[] nEndPos; //结束位置 jS3(>  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 F] ?@X  
long nFileLength; //文件长度 4UD=Y?zK  
boolean bFirst = true; //是否第一次取文件 kEhm'  
boolean bStop = false; //停止标志 ct4 [b|  
File tmpFile; //文件下载的临时信息 i4zV
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DataOutputStream output; //输出到文件的输出流 }?]yxa~  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） <o!&Kk9  
public SiteFileFetch(SiteInfoBean bean) throws IOException _b_?9b-)D  
{ .um&6Q=2<  
siteInfoBean = bean; ^qGA!_  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); X";ZUp  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); E<Dh_K  
if(tmpFile.exists ()) 6QLQ1k`  
{ BCUt`;q ]B  
bFirst = false; BBR"HMa
4  
read_nPos(); &49$hF g6"  
} Mp"'?zf  
else =Y/fF  
{ pq[X)]z|  
nStartPos = new long[bean.getNSplitter()]; W.`Xm(y  
nEndPos = new long[bean.getNSplitter()]; Zfy
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} zf3:<CRX5  

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} /8>0;bX+  
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public void run() S2&9#6  
{ %8bzs?QI  
//获得文件长度 +an^e'  
//分割文件 ^{*f3m/
 
//实例FileSplitterFetch 2Za,4'  
//启动FileSplitterFetch线程 w;c#drY7S  
//等待子线程返回 )nNCB=YF!  
try{ 'ZC}9=_g  
if(bFirst) B3dA%\'  
{ [.j]V-61  
nFileLength = getFileSize(); #PslrA. E  
if(nFileLength == -1) ]A]Ft!`6z  
{ n^AP"1l8?0  
System.err.println("File Length is not known!"); 7"F|6JP"$c  
} @q+cmJKv  
else if(nFileLength == -2) j&dx[4|m:h  
{ vS$oT]-hKE  
System.err.println("File is not access!"); &{zwM |Q@?  
} &IRA=nJ  
else ZUXse1,  
{ s~LZOPN  
for(int i=0;i<nStartPos.length;i++) *5y W  
{ n{64g+  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); V~T`&  
} '<%Nw-  
for(int i=0;i<nEndPos.length-1;i++) @P_C%}(<  
{ Any Zi'  
nEndPos = nStartPos[i+1]; ]l=O%Ev  
} eu}Fd@GO  
nEndPos[nEndPos.length-1] = nFileLength; B;GxfYj  
} L19MP  
}
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//启动子线程 Ht|",1yr+  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; $N;"}Gz  
for(int i=0;i<nStartPos.length;i++) >*`>0Q4y  
{ ?dsf@\  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3>Q@r>c  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Km)X_}|  
nStartPos,nEndPos,i); }X
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); S5~`T7Ra  
fileSplitterFetch.start();
,!6M*|  
} R:w%2Y  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ImWXzg3@{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); EO#gUv  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Fn86E dFM  
nEndPos = " + nFileLength); d7"U WY^  
// fileSplitterFetch[nPos.length-1].start(); bQwdgc),s{  
L$1K7<i.  
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//等待子线程结束 _W0OM[  
//int count = 0; D=r-  
//是否结束while循环 50LHF%  
boolean breakWhile = false;
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while(!bStop) e'1 ^+*bU  
{
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write_nPos(); !8xKf*y  
Utility.sleep(500); zmf"I[)  
breakWhile = true; /Hv*K&}M  
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for(int i=0;i<nStartPos.length;i++) <ROpuY\!l  
{ hZAG (Z  
if(!fileSplitterFetch.bDownOver) f}[H `OF  
{ #
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breakWhile = false; ~J0,)_b%*  
break; >P<z |8  
} jg[5UTkcs  
} P*pbwV#|  
if(breakWhile) r\(v+cd  
break; aS,a_b]  
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//count++; u_N\iCYp  
//if(count>4) b.#^sm
//  
// siteStop(); 8r
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} J?Ck4dQ  
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System.err.println("文件下载结束！"); Kb-W tFx  
} Rcg
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catch(Exception e){e.printStackTrace ();} ^vpIZjN  
} n`%2Mj c  
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//获得文件长度 kg<P t >  
public long getFileSize() bE?'C h  
{ UqN{JG:#.  
int nFileLength = -1; \V= &&(n#  
try{ N~;*bvW{  
URL url = new URL(siteInfoBean.getSSiteURL()); 6sPk:5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |GtY*
|  
httpConnection.setRequestProperty("User-Agent","NetFox"); /D0RC  
8;TAb.r  
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int responseCode=httpConnection.getResponseCode(); [s~JceUyX  
if(responseCode>=400) )ZGYhE  
{ zI:(33)  
processErrorCode(responseCode); 25d\!3#E  
return -2; //-2 represent access is error );nz4/V  
} kI%peb?  
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String sHeader; QU.0Elw  
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for(int i=1;;i++) D?^540,b  
{ wa!zv^;N*  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); P+h6!=nD7  
//Utility.log(in.readLine()); ^|#>zCt^  
sHeader=httpConnection.getHeaderFieldKey(i); S?L#N  
if(sHeader!=null) Go1(@  
{ eJ)1K  
if(sHeader.equals("Content-Length")) RU0i#suiz  
{ SBTPTb  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 6B#('gxO  
break; \eQla8s  
} vQ 4}WtvA  
} |zq4*  5  
else Bz+.Qa+  
break; 2{-!E ^g  
} Vo,[EVL  
} Edw2W8  
catch(IOException e){e.printStackTrace ();} QBoFpxh=  
catch(Exception e){e.printStackTrace ();} Pp+~Cir  
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Utility.log(nFileLength); o~#f1$|Xn  
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return nFileLength; icE|.[  
} 
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//保存下载信息（文件指针位置） w?*z^y@  
private void write_nPos() w$j{Hp6m  
{ DzC Df@TB"  
try{ 
6\4Z\82  
output = new DataOutputStream(new FileOutputStream(tmpFile)); l&L,7BX  
output.writeInt(nStartPos.length); RNTa XR+Zn  
for(int i=0;i<nStartPos.length;i++) rVH6QQF=\  
{ ~-_i  
// output.writeLong(nPos); gWOt]D&#/  
output.writeLong(fileSplitterFetch.nStartPos); #{$1z;i?f  
output.writeLong(fileSplitterFetch.nEndPos); sw$2d  
} H\E7o"m  
output.close(); %X>FVlPm  
} gO='A(Y  
catch(IOException e){e.printStackTrace ();} WULAty  
catch(Exception e){e.printStackTrace ();} =A@>I0(7  
} qZ*f%L(  
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Z
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//读取保存的下载信息（文件指针位置） -#.< 12M  
private void read_nPos() d yh<pX/$  
{ #6=MKpR  
try{ (wuaxo:  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); *0y{ ~@  
int nCount = input.readInt(); 19Ww3PvQ;  
nStartPos = new long[nCount]; 6)}B"Qd  
nEndPos = new long[nCount]; LL(|$}yW  
for(int i=0;i<nStartPos.length;i++) ZyI$M3{J  
{ F2;:vTA>  
nStartPos = input.readLong(); OQp, 3M{_  
nEndPos = input.readLong(); NF+<#*1  
} FI"HJwAs  
input.close(); L0Y0&;y|R  
} =gjDCx$|  
catch(IOException e){e.printStackTrace ();} 53Yxz3v  
catch(Exception e){e.printStackTrace ();} I[0!SIqY  
} M:|8]y@  
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private void processErrorCode(int nErrorCode) 6e
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{ "AC^ rz~U  
System.err.println("Error Code : " + nErrorCode); "(`2eXR
n  
} c2 Aps  
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sw;|'N$:<  
//停止文件下载 0[xpEiDx  
public void siteStop() oC*=JJe,  
{ gL3iw!7  
bStop = true; Pbn!KX~F~  
for(int i=0;i<nStartPos.length;i++) W:`#% :C  
fileSplitterFetch.splitterStop(); @gY\;[#.  
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} [AS}
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} dJ ~Zr)>  
//负责部分文件的抓取 lCIDBBjy^  
**FileSplitterFetch.java Ez+Z[*C  
*/ l_{8+\`!  
package NetFox; epg#HNP7^Y  
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import java.io.*; *?t%0){  
import java.net.*; A"uULfnk  
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public class FileSplitterFetch extends Thread { $s-Y%gc  
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String sURL; //File URL S`!-Cal`n  
long nStartPos; //File Snippet Start Position -!e7L>w  
long nEndPos; //File Snippet End Position s?rBE.g@}  
int nThreadID; //Thread's ID ZnW@YC#9  
boolean bDownOver = false; //Downing is over W*N$'%  
boolean bStop = false; //Stop identical IiJZ5'{  
FileAccessI fileAccessI = null; //File Access interface lg$zGa?  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException "=1;0uy]  
{ ;*2>ES  
this.sURL = sURL; S
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this.nStartPos = nStart; x,n,Qlb  
this.nEndPos = nEnd; ~P.I<  
nThreadID = id; IkPN?N  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 k*mt4~KLT8  
} 7zemr>sIh  
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public void run() Cbm\h/PXl  
{ `aC){&
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while(nStartPos < nEndPos && !bStop) . pzC5Ah  
{ z (?=Iv3  
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try{ he(A3{'  
URL url = new URL(sURL); `=lc<T^  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); "N?+VkZEv  
httpConnection.setRequestProperty("User-Agent","NetFox"); u #w29Pm  
String sProperty = "bytes="+nStartPos+"-"; (kv?33  
httpConnection.setRequestProperty("RANGE",sProperty); _)T5lEFl=  
Utility.log(sProperty); ml`8HXK0  
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InputStream input = httpConnection.getInputStream(); A/7{oB:a  
//logResponseHead(httpConnection); ,Wbwg  
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byte[] b = new byte[1024]; 6( CDNMzj  
int nRead; Jg}K.1Hs  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) T~0k"uTE  
{ K%v1xZ  
nStartPos += fileAccessI.write(b,0,nRead); \%]I{  
//if(nThreadID == 1) hrGM|_BE  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ~\LCvcY"X  
} ).^}AFta  
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Utility.log("Thread " + nThreadID + " is over!"); Eow_&#WW;P  
bDownOver = true; l vMlL5t  
//nPos = fileAccessI.write (b,0,nRead); hCjR&ZA  
} L>yJ  
catch(Exception e){e.printStackTrace ();} W\&8auds  
} x^4xq#Bb7  
} Qx;\USv  
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//打印回应的头信息 SCvVt  
public void logResponseHead(HttpURLConnection con) N,8/Y  
{ =U%Rvm  
for(int i=1;;i++) -K9c@?  
{ p$Ox'A4  
String header=con.getHeaderFieldKey(i); aT>'.*\]  
if(header!=null) mGp.3{j  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); {M-YHX>*;g  
Utility.log(header+" : "+con.getHeaderField(header)); Lzu.)C@Amx  
else y{dTp  
break; .ZvM^GJb  
} ![]``g2  
} i;LXu%3\  
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public void splitterStop() I!e})Y  
{ S;$-''o?9  
bStop = true; wiz$fj  
} ]o cWt3|  
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} [0"'T[ok  
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/* bFe+m1Q_  
**FileAccess.java _?OW0x4  
*//文件访问(定位，写) oD<kMK  
package NetFox; JSW^dw&  
import java.io.*; |B?27PD  
O8B\{T1  
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public class FileAccessI implements Serializable{ s2Mb[#:a"  
{ ^cV lC_  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 su*'d:L  
RandomAccessFile oSavedFile; %Ev4]}2C1  
long nPos; 0NS<?p~_S  
/YZr~|65  

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public FileAccessI() throws IOException ,%uo6%  
{ o4|M0  
this("",0); E[/\7v\  
} SQX:7YF~  
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public FileAccessI(String sName,long nPos) throws IOException 8C*c{(4  
{ 3AU;>D^5  
oSavedFile = new RandomAccessFile(sName,"rw"); Kx>qz.wwI?  
this.nPos = nPos; 9WyAb3d'  
oSavedFile.seek(nPos); ;W,XP#{W  
} pt<!b0G  
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public synchronized int write(byte[] b,int nStart,int nLen) "- @{ )  
{ H(9%SP@[c  
int n = -1; GhpVi<FL  
try{ lgFA}p@  
oSavedFile.write(b,nStart,nLen); q|BR-0yi  
n = nLen; C-'n4AY^  
} 'AU(WHf  
catch(IOException e) Bpt%\LK\~O  
{ :td6Mywl  
e.printStackTrace (); %
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} Q$Qs$  
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return n; 2Sbo7e  
} B'"(qzE-kM  
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} Uu ~BErEC  
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/* Wm\HZ9PN  
**SiteInfoBean.java unu%\f>^4  
*/ $}RBK'cr}  
package NetFox; ,pL%,>R5  
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public class SiteInfoBean { %_C!3kKv~  
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sT:$:=  
private String sSiteURL; //Site's URL ~x;1&\'k  
private String sFilePath; //Saved File's Path }qU(G3  
private String sFileName; //Saved File's Name l2Z!;Wm(  
private int nSplitter; //Count of Splited Downloading File @)=\q`vV  
$?RxmWsP  
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public SiteInfoBean() 'k[d&sR  
{//nSplitter的缺省值为5 +EG?8L,z  
//default value of nSplitter is 5 tmEF7e`(o  
this("","","",5); &U/7D!^X  
} W(U:D?e  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) aoj6/  
{ 1}nrVn[B9  
sSiteURL= sURL; ~k>H4hV3  
sFilePath = sPath; ?IgM=@  
sFileName = sName; %GS^=Qr  
this.nSplitter = nSpiltter; vt)u`/u  
<^>O<P:v  
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} Za,rht  
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public String getSSiteURL() Dn/{  s$\  
{ j)?[S  
return sSiteURL; '4 T}$a"i  
} &Luq}^u  
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m/}(dT;  
public void setSSiteURL(String value)  g=W1y  
{ K[}5bjh>  
sSiteURL = value; k~ Z9og  
} -pEt=  
qQ\&]  
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public String getSFilePath() J*HZ=6L  
{ Si=zxy
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return sFilePath; qy@v,a  
} <X]'":  
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4#D=+70'  
public void setSFilePath(String value) 8K(3{\J[V  
{ [!Uzw2  
sFilePath = value; EVs.'Xg<  
} v&}+ps_W  
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public String getSFileName() Gp*U2LB  
{ up`.#GWm  
return sFileName; DVNx\t  
} 66RqjP '2  
-<e8\Z`  
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public void setSFileName(String value) gZkjh{rQ  
{ w.v yEU^  
sFileName = value;
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} E1'| ;}/  
k)l*L1Y4:  
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public int getNSplitter() {zGM[A  
{
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return nSplitter; #$/SM_X14C  
} P!uwhha/g  
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public void setNSplitter(int nCount) ]<y _ =>  
{ g$=y#<2?  
nSplitter = nCount; *c"tW8uR  
} 2oL~N*^C  
} snU $Na3  
& QO9/!  
"Yh[-[,  
/* ?r< F/$/  
**Utility.java fg[]>:ZT.  
*/ SU.9;I !  
package NetFox; `8 Q3=^)3  
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public class Utility { "v%|&@  
R 2.y=P8N  
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public Utility() {~cG'S Y%  
{ z'iAj  
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} 8|9JJ<G7  
c{X>i>l>  
//线程睡眠 &RSUB;ymL  
public static void sleep(int nSecond) JI&ik_k3  
{ Ky6.6Y<.|  
try{ Ndb_|  
Thread.sleep(nSecond); W PDL$y  
} *^h$%<QI  
catch(Exception e) D I` M  
{ f[S$Gu4-  
e.printStackTrace (); 8[2.HM$Y  
} KDt@Xi6||  
} Z:TW{:lrI  
X?3?R\/  
//日志 oh>X/uj  
public static void log(String sMsg) DM*GvBdR  
{ \a\J0&Z  
System.err.println(sMsg); |dP[_nh?  
} R9dC$Y]\M  
m\h. sg&  
Q#
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public static void log(int sMsg) S`N_},  
{ 2!UNFv#=$  
System.err.println(sMsg); C}})dL;(  
} \1^qfw  
} N.j?:  
 ~\0uy3%  
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/* O-5s}RT  
**TestMethod.java ^N{Lau  
*/ +x?_\?&Ks  
package NetFox; -~wGJM VA  
WKHEU)'!  
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public class TestMethod { N s
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w-[A"M]I  
@(;zU~l/  
public TestMethod() 
yP&SA+  
{ ///xx/weblogic60b2_win.exe rXortK#\%  
try{ bU(H2Fv  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); )JYt zc  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); #gHs!b-g@  
SiteFileFetch fileFetch = new SiteFileFetch(bean);  xr }jw  
fileFetch.start(); +N~?_5lv\s  
} &HS6}  
catch(Exception e){e.printStackTrace ();} 8ec6J*b  
AX {~A:B  
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} 4sj:%%UE  
^CZ)!3qd1  
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public static void main(String[] args) d;Uzl1;  
{ pO2Y'1*  
new TestMethod(); aP%&-W$D|  
} L `7~~  
} ,g2oqq ?  
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