http断点续传简单实现（java)

/* ]qc2jut"  
**SiteFileFetch.java S-+^L|  
*/ meV RdQ  
package NetFox; S b3@7^  
import java.io.*; ktKT=(F&  
import java.net.*; hC=="4 -  
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public class SiteFileFetch extends Thread { mWM!6"  
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SiteInfoBean siteInfoBean = null; //文件信息Bean [(N<E/m%B  
long[] nStartPos; //开始位置 %fz!'C_4  
long[] nEndPos; //结束位置 SSF4P&  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Wz7jB6AWA  
long nFileLength; //文件长度 "L" 6jT  
boolean bFirst = true; //是否第一次取文件 p(Q5!3C0q  
boolean bStop = false; //停止标志 _\LAWQ|M4[  
File tmpFile; //文件下载的临时信息 &6L{1  
DataOutputStream output; //输出到文件的输出流 Sf\mg4,  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） b fsTeW+  
public SiteFileFetch(SiteInfoBean bean) throws IOException ,9p 4(jjX  
{ Kq;
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siteInfoBean = bean; |ldRs'c{  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 6(}8[i:  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ,#r>#fi0  
if(tmpFile.exists ()) ""ICdZ_A  
{ r#pC0Yj!3  
bFirst = false; 8+1tys  
read_nPos(); 7>J8\=  
} ;[@< ,  
else Ui7S8c#tH  
{ j>Htaa  
nStartPos = new long[bean.getNSplitter()]; .Eg>)  
nEndPos = new long[bean.getNSplitter()]; @vaK-&|#$  
} Ro?aDrQ  
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} DO$jX 4  
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public void run() ;Z"6ve4  
{ ]J C}il_b  
//获得文件长度 MI@id  
//分割文件 ?j8F5(HF?  
//实例FileSplitterFetch B@l/'$G  
//启动FileSplitterFetch线程 ;%AK< RT  
//等待子线程返回 [L,Tf_t^Y  
try{ ,r
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if(bFirst) /AP@Bhm  
{ yla&/K;|*  
nFileLength = getFileSize(); F%x8y  
if(nFileLength == -1) </|I
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{ *O|Z[>  
System.err.println("File Length is not known!"); Llk4=p  
} T'l >$6  
else if(nFileLength == -2) {ls$#a+d  
{ ^~2GhveBV  
System.err.println("File is not access!"); 0t1WvW  
} { CkxUec  
else <w.W[ak  
{ V3-5:z  
for(int i=0;i<nStartPos.length;i++) b$+.}&M  
{ J]~LmSh  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); R$=UJ}>  
} w Maib3Q  
for(int i=0;i<nEndPos.length-1;i++) EOjo>w>  
{ k9.2*+vvg  
nEndPos = nStartPos[i+1]; |jniI(  
} [|\~-6"7N|  
nEndPos[nEndPos.length-1] = nFileLength; 8|`4D 'Ln  
} jnX9] PkJ  
} )G0a72  
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DGTSk9iK(  
//启动子线程 1_!*R]aq  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 70l"[Y  
for(int i=0;i<nStartPos.length;i++) &CFHH"OsT  
{ /v E>*x  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), B]q &?~  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ~&=-*  
nStartPos,nEndPos,i); }N1Z7G  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); T2 0dZ8{y  
fileSplitterFetch.start(); ]C-hl}iq  
} ]%3o"|  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), hp!UW  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); `
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 2;NIUMAMM  
nEndPos = " + nFileLength); v"Fa_+TVx  
// fileSplitterFetch[nPos.length-1].start(); Kgi%Nd  
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qIa|sV\w0  
//等待子线程结束 AxUj CerNf  
//int count = 0; =u(. Y  
//是否结束while循环 ^S'}RZ*>  
boolean breakWhile = false; ;GO>#yg4Eh  
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while(!bStop) Q_xE:#!;  
{ yw2^kk93|  
write_nPos(); c-!rJHL`  
Utility.sleep(500); iK1<4
)  
breakWhile = true; 1K&z64Q5J  
[J0L7p*6  
RX%*:lXi_  
for(int i=0;i<nStartPos.length;i++) !MNUp(:  
{ w%)=`'s_  
if(!fileSplitterFetch.bDownOver) nM1U=Du  
{ BDyOX6  
breakWhile = false; E% Ce/n  
break; hVI $r  
} Y(ly0U}  
} r>sk@[4h  
if(breakWhile) f7}/ {}g  
break; Z}TuVE  
c$Js<[1  
?&ThMWl  
//count++; {e A4y~k  
//if(count>4) SJ;u,XyWn  
// siteStop(); a1]k(AuQrC  
} d {a^  
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System.err.println("文件下载结束！"); qdrk.~_  
} 1Dg\\aUk  
catch(Exception e){e.printStackTrace ();} mF[w-<:.d  
} ScYw3i  
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//获得文件长度 &F*s.gL  
public long getFileSize() B@` 87  
{ R4u=
.  
int nFileLength = -1; z@^[.  
try{ meT~b  
URL url = new URL(siteInfoBean.getSSiteURL()); mdR:XuRD"t  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |S|0'C*  
httpConnection.setRequestProperty("User-Agent","NetFox"); ~T9%%W[  
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int responseCode=httpConnection.getResponseCode(); E8u:Fgs  
if(responseCode>=400) I4ZL+a  
{ N\1!)b  
processErrorCode(responseCode); &/}]9 #  
return -2; //-2 represent access is error | Uf6k`  
} sptDzVM  
;(fDR8  
>XjSVRO  
String sHeader; h.ojj$f,  
*fso6j#%  
(p'yya{(  
for(int i=1;;i++) |\%[e@u  
{ kMAQHpDD  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); nVko]y  
//Utility.log(in.readLine()); KlDW'R$  
sHeader=httpConnection.getHeaderFieldKey(i); uuHR!  
if(sHeader!=null) X90
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{ )uiYu3 I  
if(sHeader.equals("Content-Length")) o {Sc  
{ \:]Clvc  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); {$)zC*l  
break; r5> FU>7'  
} oE[wOq+  
} p<*3mbgGO  
else -gefdx6ES  
break; F]\(p=U.  
} xGCW-YR9  
} !*ct3{m  
catch(IOException e){e.printStackTrace ();} 
pw" !iG}  
catch(Exception e){e.printStackTrace ();} M.))UKSF  
>{p&_u.r-  
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Utility.log(nFileLength); }&Un8Rg"h  
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return nFileLength; ^EWkJW,Yc  
} \:9dt8(-U  
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wv>*g:El'  
//保存下载信息（文件指针位置） zD:"O4ZM^^  
private void write_nPos() O-y/K2MC*  
{ k'E3{8<!  
try{ Mh"DPt9@J  
output = new DataOutputStream(new FileOutputStream(tmpFile)); %yX?4T;b  
output.writeInt(nStartPos.length); 2jV.\
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for(int i=0;i<nStartPos.length;i++) losm<  
{ [Hw  
// output.writeLong(nPos); 6z=h0,Y}  
output.writeLong(fileSplitterFetch.nStartPos); QE*O~Yj  
output.writeLong(fileSplitterFetch.nEndPos); 16ahU$@-  
} ~A2{$C  
output.close(); =B<>H$  
} r:lv[/D  
catch(IOException e){e.printStackTrace ();} a|rN %hA4  
catch(Exception e){e.printStackTrace ();} ~=91Kxf  
} A&X(\c M  
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sS(t }$  
//读取保存的下载信息（文件指针位置） ".A+'pJ
  
private void read_nPos() yoiKt; S  
{ 0YK`wuZGS  
try{ nXPl\|pXt  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); IV*@}~BJ  
int nCount = input.readInt(); nf=*KS\v  
nStartPos = new long[nCount]; 9o5W\.A7[D  
nEndPos = new long[nCount]; %Z9&zmO  
for(int i=0;i<nStartPos.length;i++) .'N:]G@!  
{ {\z&`yD@  
nStartPos = input.readLong(); |C}n]{*|  
nEndPos = input.readLong(); 07 [%RG  
} i3#To}g5V  
input.close(); idW
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} F5la:0fb  
catch(IOException e){e.printStackTrace ();} !=%0  
catch(Exception e){e.printStackTrace ();} q)vdDdRe_  
} zmd,uhNc:  
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private void processErrorCode(int nErrorCode) %;ZWYj`]n  
{ yN}upYxp  
System.err.println("Error Code : " + nErrorCode); FN jT?*  
} l3kYfq{";"  
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hbl%<ItI49  
//停止文件下载 P7ktr?V0a  
public void siteStop() 9D@ $Y54  
{ ML@-@BaN  
bStop = true; i4;`dCT|A  
for(int i=0;i<nStartPos.length;i++) rP$vZ
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fileSplitterFetch.splitterStop(); RO.GD$ 3n  
@!k\Ivd  
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} 5@l[!Jl0k  
} XRoMD6qf;  
//负责部分文件的抓取 GVS-_KP\  
**FileSplitterFetch.java l{q$[/J~)  
*/ Z9Prw/8P  
package NetFox; K5l#dl_T  
[O~'\Q  
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import java.io.*; :lf;CT6$  
import java.net.*; OSP#FjH  
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public class FileSplitterFetch extends Thread { @;>i3?  
:eIPPh|\  
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String sURL; //File URL >!
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long nStartPos; //File Snippet Start Position 1K(a=o[Ce  
long nEndPos; //File Snippet End Position S}fU2Wi  
int nThreadID; //Thread's ID &G63ReW7 @  
boolean bDownOver = false; //Downing is over "s-e)svB  
boolean bStop = false; //Stop identical <3?T^/8  
FileAccessI fileAccessI = null; //File Access interface 9gjI;*(z1  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException WH:[Y7D  
{ fpMnA  
this.sURL = sURL; KKMzhvf]#  
this.nStartPos = nStart; epz'GN]V  
this.nEndPos = nEnd; 85;hs  
nThreadID = id; J6m`XC  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 -anLp8G*  
} 'p0|wM_  
%Xm3m0nsv{  
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public void run() \=n0@1Q=>  
{ O<}^`4d  
while(nStartPos < nEndPos && !bStop) /WIO@c  
{ gkxEy5c[  
s=)0y$  
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try{ #$\cRLPg  
URL url = new URL(sURL); Y# <38+Gd  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); HbQvu@  
httpConnection.setRequestProperty("User-Agent","NetFox"); "v.]s;g  
String sProperty = "bytes="+nStartPos+"-"; P<+y%g(({  
httpConnection.setRequestProperty("RANGE",sProperty); m3|KIUP  
Utility.log(sProperty); 'Na \9b(  
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InputStream input = httpConnection.getInputStream(); Y>OL2g  
//logResponseHead(httpConnection); k:?+75?$  
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byte[] b = new byte[1024]; T9 @^@l$  
int nRead; i?7%z`  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) {HgW9N(  
{ re.%$D@  
nStartPos += fileAccessI.write(b,0,nRead); ]U :1NC"  
//if(nThreadID == 1) p(2j7W-/  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ,H{ /@|RW  
} 6k#H>zY,  
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Utility.log("Thread " + nThreadID + " is over!"); $Cu/!GA4.>  
bDownOver = true; *q5'~)W<  
//nPos = fileAccessI.write (b,0,nRead); ]mU,y$IQ  
} vBUl6EmWu  
catch(Exception e){e.printStackTrace ();} Oto
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} ?nm:e.S+?  
} !U02>X   
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//打印回应的头信息 )G(6=l*  
public void logResponseHead(HttpURLConnection con) ^V^In-[!y:  
{ =hV-E D  
for(int i=1;;i++) V/j]UK0$  
{ gto@o\&=  
String header=con.getHeaderFieldKey(i); dEXHd@"H  
if(header!=null) Pn{yk`6E  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); -KRHcr \  
Utility.log(header+" : "+con.getHeaderField(header)); @5gZK[?|I  
else r#{r]q_E*  
break; tVx.J'"Y  
} T7;)HFGeW  
}  m8rz i:
 
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public void splitterStop() Z2chv,SqCJ  
{ uCK!lq-  
bStop = true; =goZI67  
} 2|k*rv}l  

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} ,5\:\e0H  
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/* =q|fe%#  
**FileAccess.java uTJi }4cw  
*//文件访问(定位，写) p71%-nV  
package NetFox; ?o0#h  
import java.io.*; dRZor gar  
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w
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public class FileAccessI implements Serializable{ !2x"'o  
Q6S[sTKR  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 oB[3?
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RandomAccessFile oSavedFile; <$.KCLP  
long nPos; 4Uz:zB  
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public FileAccessI() throws IOException )!dELS\ix  
{ <.3@-z>w2,  
this("",0); tC+9W1o  
} b*Ipg8n+  

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public FileAccessI(String sName,long nPos) throws IOException Xi5kE'_  
{ [
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oSavedFile = new RandomAccessFile(sName,"rw"); /2u;w!oi.  
this.nPos = nPos; v\Y;)/!  
oSavedFile.seek(nPos); '$)
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} |xzqYu?o  
v>3ctP{  
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public synchronized int write(byte[] b,int nStart,int nLen) <YL\E v/[  
{ kyJv,!};  
int n = -1; wrG*1+r
 
try{ #)R;6"  
oSavedFile.write(b,nStart,nLen); s)=L6t^a6  
n = nLen; lGB7(  
} X_ >B7(k   
catch(IOException e) >/n5=RWh  
{ V`69%35*@  
e.printStackTrace (); >1ZMQgCG  
} cXJgdBwo  
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return n; VhSKtD1  
} xSb/98;  
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} -lL*
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QBto$!})  
/* 3|:uIoR{  
**SiteInfoBean.java ](_(1  
*/ |ry;'[*  
package NetFox; U7crbj;c)d  
any\}   
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public class SiteInfoBean { W&06~dI1!  

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private String sSiteURL; //Site's URL lRt8{GFy  
private String sFilePath; //Saved File's Path 4)j<(5  
private String sFileName; //Saved File's Name ]^ O<WD  
private int nSplitter; //Count of Splited Downloading File 6}NvVolr  
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hQGZrZK#  
public SiteInfoBean() P>N\q
  
{//nSplitter的缺省值为5 ;JL@V}L,  
//default value of nSplitter is 5 aDZLabRu  
this("","","",5); mA^>Y_:  
} y6*i/3  
=r0!-[XCa  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) YSrFHVq  
{ ObM5vrEk|  
sSiteURL= sURL; }Pb!u9_  
sFilePath = sPath; cjN4U [  
sFileName = sName; 3C,e>zE}  
this.nSplitter = nSpiltter; b}"/K$`Fd  
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i0AC.]4e"  
} BC
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&\p:VF.  
public String getSSiteURL() %oor7 -l  
{ g"Ii'JZ?  
return sSiteURL; wFqz.HoB  
} mOXI"q]p  
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public void setSSiteURL(String value) jilO%  "  
{ Y6N+,FAk+J  
sSiteURL = value; |9\Lv$
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} D[tGbk  
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public String getSFilePath() p`d:g BZ  
{ ]hf4= gm  
return sFilePath; k6Tpaf^  
} !m(6/*PAl  
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public void setSFilePath(String value) SiBbz4  
{ 3:;%@4f  
sFilePath = value; b6/:reH{  
} I(7gmCV  
shn-Es*  
+?@qux!  
public String getSFileName() L0_=R;.<  
{ dJ&s/Z/>E  
return sFileName; >y8Z{ALQ5  
} 3o^V$N.  
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public void setSFileName(String value) &YMVoyVD  
{ Y-{spTI  
sFileName = value; WI~%n  
} VmT5?i   
L+kS8D<  

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public int getNSplitter() cXCczqabv  
{ v*^2[pf  
return nSplitter; ,pG63&?j  
} '#Fh J%x  
U92hv~\  
#62ww-E~  
public void setNSplitter(int nCount) T a[74;VO  
{ @"EX%v.  
nSplitter = nCount; ;yXnPAtJ  
} =N0cz%  
} =~S   
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/* vVf!XZF  
**Utility.java )/pPY  
*/ 5(|ud)v  
package NetFox; HWU{521  
bbM !<&F  
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public class Utility { 0zxeA+U  
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public Utility() S\rfR N  
{ ;lEiOF+d  
lpM{@JC  
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} fh3 6  
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//线程睡眠 m{y
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public static void sleep(int nSecond) syfR5wc  
{ Bx)&MYY}[[  
try{ 4%7*tVG  
Thread.sleep(nSecond); -XyuA:pxx  
} \* #4  
catch(Exception e) .KSGma6]  
{ 6};oLnO  
e.printStackTrace (); o
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} Qw-qcG  
} Dw[Q,SE  
 zVa+5\Q  
//日志 ZSSgc0u^?  
public static void log(String sMsg) ?yb{DZ46  
{ D-!%L<<  
System.err.println(sMsg); zK92:+^C  
} BkeP?X  
m>!#}EJ|  
el%Qxak`"  
public static void log(int sMsg) ;CZcY] ol  
{ BYf"l8^,  
System.err.println(sMsg); h:NXO'  
} !;a<E:  
} 7q=0]Hrg(D  
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3Cl9,Z"&6$  
/* Uf<vw3  
**TestMethod.java gk#rA/x  
*/ f+Go8Lg=M  
package NetFox; a40BisrD~6  
>KFJ1}b|3  
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public class TestMethod { 8IH gsW";  
c53`E U  
"U.=A7r  
public TestMethod() :JIPF=]fc  
{ ///xx/weblogic60b2_win.exe *ZGN!0/  
try{ 0}V'\=F454  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); y<b0z\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Y5CE#&  
SiteFileFetch fileFetch = new SiteFileFetch(bean); DPx,qM#h5O  
fileFetch.start(); J
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} A{%;Hd`0/  
catch(Exception e){e.printStackTrace ();} 6zWvd  
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6f!mk:\T.  
} "tARJW  
^'4uTbxP_!  
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public static void main(String[] args) bl<7[J.  
{ z;
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new TestMethod(); . 6dT5x8u  
} ^ym{DSx  
} ^aCYh[
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