http断点续传简单实现（java)

/* Ze#DFe$  
**SiteFileFetch.java x7`+T1IJ  
*/ ;)P=WS:=  
package NetFox; TqfL Sm|  
import java.io.*; }:;UnE}  
import java.net.*; Km,o+9?1gF  
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public class SiteFileFetch extends Thread { ;fN^MW@&[  
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SiteInfoBean siteInfoBean = null; //文件信息Bean \+l_H4\`K  
long[] nStartPos; //开始位置 iDhC_F|  
long[] nEndPos; //结束位置 DQc\[Gq&  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 kp}[nehF  
long nFileLength; //文件长度 s@y;b0
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boolean bFirst = true; //是否第一次取文件 oGl<i  
boolean bStop = false; //停止标志 .c0u##/0  
File tmpFile; //文件下载的临时信息 v9S=$Aj  
DataOutputStream output; //输出到文件的输出流 #Er"i  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） <o*b6m%  
public SiteFileFetch(SiteInfoBean bean) throws IOException 6-J}ZfGj  
{ y'>JT/Q5  
siteInfoBean = bean; 6%>'n?  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 6?C';1  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); *vEj\  
if(tmpFile.exists ()) tns8B  
{ T:H~Y+qnt  
bFirst = false; 9&`";
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read_nPos(); >7~*j4g  
} 4m"0R\  
else a l6y=;\jZ  
{ [C<
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nStartPos = new long[bean.getNSplitter()]; M*Ej*
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nEndPos = new long[bean.getNSplitter()]; "+wkruC  
} S?C.:  
/
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} H{S+^'5Y.  
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public void run()  .P")S|  
{ mU?~s7  
//获得文件长度 4dLnX3 v  
//分割文件 q5'G]j{,Z  
//实例FileSplitterFetch pPo(nH|<  
//启动FileSplitterFetch线程 ?_A[E]/H  
//等待子线程返回 d!Gy#<H  
try{ ]7yxXg  
if(bFirst) z\" .(fIV  
{ tY!l}:E[  
nFileLength = getFileSize(); udBIEW,`  
if(nFileLength == -1) N}ND()bf  
{ S4{vS?>j  
System.err.println("File Length is not known!"); .s!0S-RkC  
} RjPkH$u'Pj  
else if(nFileLength == -2) =s]2?m  
{ r Dlu&  
System.err.println("File is not access!"); ,Tegrz&G  
} Dc$q0|N=z  
else cg17e  
{ Dykh|"  
for(int i=0;i<nStartPos.length;i++) !X~NL+  
{ ZeU){CB  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ~ho,bwJM[T  
} :l!sKT?:d!  
for(int i=0;i<nEndPos.length-1;i++) !t"/w6X1I  
{ <2&qIvHL  
nEndPos = nStartPos[i+1]; Tj_K5uccU}  
} ^L)3O|6c  
nEndPos[nEndPos.length-1] = nFileLength; izaqEz  
} I *sT*;U  
} "RK"Pn+  
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//启动子线程 hZL!%sL7  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; b|DU  
for(int i=0;i<nStartPos.length;i++) f:&JKB)N  
{ O TlqJ  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), %N~c9B  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), p}1gac_c  
nStartPos,nEndPos,i); hp(MKfhH  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); LTo!DUi
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fileSplitterFetch.start(); jy5[K.  
} 'l~7u({u  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), y] D\i5Xv  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); o4EY2  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", y'odn;  
nEndPos = " + nFileLength); ,e;,+w=~E  
// fileSplitterFetch[nPos.length-1].start(); VV/T)qEe7>  
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wZ\93W-}  
//等待子线程结束 iBbaHU*V  
//int count = 0; V'W*'wo  
//是否结束while循环 \-6y#R-B  
boolean breakWhile = false; ; I-6H5
  
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while(!bStop) >W-xDzJry  
{ \9V_[xD+  
write_nPos(); 6c-'CW  
Utility.sleep(500); ri59LYy=  
breakWhile = true; PDA9.b<q0  
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for(int i=0;i<nStartPos.length;i++) 6IT6EkiT  
{ kjV>\e  
if(!fileSplitterFetch.bDownOver) VgYy7\?p  
{ fDB.r$|d  
breakWhile = false; 4C_1wk('  
break; YB4 ZI  
} :KX*j$5U  
} F#<:ZByjJ@  
if(breakWhile) 2D"my]FnF  
break; `V V>AA5  
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|&MoQxw@  
//count++; +,)k@OI  
//if(count>4) ll$mRC  
// siteStop(); uuFQTx))  
} WeH_1$n5  
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!\%JOf}  
System.err.println("文件下载结束！"); oi7k#^  
} = E_i  
catch(Exception e){e.printStackTrace ();} Y]`=cR`/"  
} ETL7|C"  
(9aOET>GG  
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//获得文件长度 B\rY\  
public long getFileSize() PZV>A!7C8n  
{ <HRPloVKo  
int nFileLength = -1; ,{q#U3  
try{ 0.R3(O  
URL url = new URL(siteInfoBean.getSSiteURL()); O ] !tK  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); PV"\9OIKb.  
httpConnection.setRequestProperty("User-Agent","NetFox"); iN'T^+um=  
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int responseCode=httpConnection.getResponseCode(); ^J7q,tvbJ  
if(responseCode>=400) ['\R4H!x  
{ 6q>iPK Jt  
processErrorCode(responseCode); K*Ba;"Ugeg  
return -2; //-2 represent access is error .{8[o[w =  
} iCiKr aW  
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String sHeader; CXoiA"P  
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for(int i=1;;i++) :EHk]Hkz  
{ DpmAB.  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); oO?+2pTQV  
//Utility.log(in.readLine()); Q!IqvmO  
sHeader=httpConnection.getHeaderFieldKey(i); l
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if(sHeader!=null) Y9#dAI[Gce  
{ 1:T"jsWw  
if(sHeader.equals("Content-Length")) ET9tn1  
{ yc7b%T*Y  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); O_2o/  
break; m2(}$z3e  
} Ucy=I$"  
} Q Rr9|p{  
else Ofoh4BL'1@  
break; 4pXY7+e2'  
} ~e[qh+  
} Z7y%  
catch(IOException e){e.printStackTrace ();} Kg<~Uf=1  
catch(Exception e){e.printStackTrace ();} 1nvT={'R  
5 8;OTDR!  
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Utility.log(nFileLength); Ex_dqko  
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return nFileLength; pl,XS6mB  
} @Q ~;@M  

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//保存下载信息（文件指针位置） A9ld9R  
private void write_nPos() 0VJHE~Bgi  
{ Z)(#D($-  
try{ _M7|:*  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Xu#?Lw  
output.writeInt(nStartPos.length); DU*qhW`X  
for(int i=0;i<nStartPos.length;i++) .@;5"  
{ K9ih(fh)  
// output.writeLong(nPos); wS7Vo{#@\  
output.writeLong(fileSplitterFetch.nStartPos); Kt]vTn7!9  
output.writeLong(fileSplitterFetch.nEndPos); Fpn'0&~-fi  
} +B+cN[d  
output.close(); c@]G;>o  
} A -8]4p::  
catch(IOException e){e.printStackTrace ();} u0?TMy.%  
catch(Exception e){e.printStackTrace ();} c-.F{~  
} $'!n4}$}  
^l ;Bo3^_  
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//读取保存的下载信息（文件指针位置） '_K`1&#U  
private void read_nPos() zh?
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{ -g9CW[  
try{ $OGMw+$C^  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); b/#<::D `  
int nCount = input.readInt(); 1UrkDz?X  
nStartPos = new long[nCount]; 91a);d  
nEndPos = new long[nCount]; / )[\+Nc  
for(int i=0;i<nStartPos.length;i++) @LU[po1I  
{ e2nZwPH  
nStartPos = input.readLong(); ? )IH#kL  
nEndPos = input.readLong(); w+\RSqz/  
} /@&uaw  
input.close(); ,gkWksl9  
} h"2^` )!u  
catch(IOException e){e.printStackTrace ();} oc-o>H  
catch(Exception e){e.printStackTrace ();} @JP6F[d  
} iztF  
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private void processErrorCode(int nErrorCode) OWYY2&.h  
{ +@@( C9  
System.err.println("Error Code : " + nErrorCode); 7 X~JLvN  
} #fyY37-  
* _,yK-et  
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//停止文件下载 D2:ShyYAS  
public void siteStop() p1z^i(  
{ EScy!p\*  
bStop = true; $VxuaOTyVZ  
for(int i=0;i<nStartPos.length;i++) ) I.uqG  
fileSplitterFetch.splitterStop(); WCI'Kh 
 
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} %Si3LQf  
} bXHtw}n  
//负责部分文件的抓取 g87M"kQKA  
**FileSplitterFetch.java Zl2doXC  
*/ 7H[.o~\  
package NetFox; _p+q)#.W  
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import java.io.*; &G+:t)|S  
import java.net.*; \FyHIs  
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public class FileSplitterFetch extends Thread { fhQ N;7  
-]MZP:s  
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String sURL; //File URL 8O^z{Yh7  
long nStartPos; //File Snippet Start Position }GGH:v
 
long nEndPos; //File Snippet End Position r
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int nThreadID; //Thread's ID OgyHX>}bH  
boolean bDownOver = false; //Downing is over D_I_=0qNd  
boolean bStop = false; //Stop identical 8GT{vW9  
FileAccessI fileAccessI = null; //File Access interface m] IN-'  
&)Iue<&2  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException IA
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{ Uw>g^[V;  
this.sURL = sURL; `q1K%id  
this.nStartPos = nStart; SL%lY  
this.nEndPos = nEnd; %|?PG i@5  
nThreadID = id; ,tOc+3Qz$  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ?u M2|Nk  
} >K;C?gHo  
("@ih]zYf  
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public void run() Aj2yAg  
{ e_CgZ  
while(nStartPos < nEndPos && !bStop) s$OnQc2/  
{ ,7|2K&C5  
}o#6g|"\sY  
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try{ &r!*Y&  
URL url = new URL(sURL); 5?4jD]Z  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); XhJbBVS|  
httpConnection.setRequestProperty("User-Agent","NetFox"); td
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String sProperty = "bytes="+nStartPos+"-"; ZZ{:f+=?$  
httpConnection.setRequestProperty("RANGE",sProperty); pWXoJ0N  
Utility.log(sProperty); dJd(m&.|N  
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InputStream input = httpConnection.getInputStream(); M2e_)f:  
//logResponseHead(httpConnection); Ce1^S[
 
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byte[] b = new byte[1024]; 8!{F6DG  
int nRead; $17utJ58  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) J(\f(jh/  
{ elf2!  
nStartPos += fileAccessI.write(b,0,nRead); F&x9.  
//if(nThreadID == 1) %B'*eBj~fw  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -5t
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} DkGC+Dw  
!Wz%Hy:ZK  
!r*Ogv[  
Utility.log("Thread " + nThreadID + " is over!"); \sZ!F&a~  
bDownOver = true; 0(!D1G{ul  
//nPos = fileAccessI.write (b,0,nRead); h*9s^`9)  
} A296f(  
catch(Exception e){e.printStackTrace ();} VdV18-ea  
} UFy"hJchO  
} eE/E#W8  
}<hyW9  
2-*zevPiG=  
//打印回应的头信息 Jx8?x#}  
public void logResponseHead(HttpURLConnection con) ~4fjFo&_\  
{ (\<#fkeH  
for(int i=1;;i++) CPCjY|w7   
{ .A`Q!  
String header=con.getHeaderFieldKey(i); 2'zYrdem  
if(header!=null) +5:oW~ ;  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); yY$:zc"J  
Utility.log(header+" : "+con.getHeaderField(header)); >F~]r$G  
else 0"_FQv  
break; Spossp`|  
} <Prz>qL$  
} nT.2HQ((Xg  
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pIy+3&\e;  
public void splitterStop() !!4` #Z0+#  
{ D> |R.{  
bStop = true; ' s6SKjZS  
} AF}6O(C~  
!Z*2X ^  
~;A36M-[.  
} vf+GC*f  
2}P?N  
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/* B~oc.sg  
**FileAccess.java Lgh. 1foK  
*//文件访问(定位，写) &nk[gb o\  
package NetFox; I8C(z1(N  
import java.io.*; 9fyJw1  
"Y Z B@  
YVMwb@|  
public class FileAccessI implements Serializable{ GDgq 4vfj  
V~> x\  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 WML%yO\.;  
RandomAccessFile oSavedFile; [h>RO55e  
long nPos; <TL!iM  
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public FileAccessI() throws IOException 6 ZutU ~HS  
{ /K{`gc  
this("",0); FCu0)\  
} )!:}R}q  
7n,*3;I  
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public FileAccessI(String sName,long nPos) throws IOException j~d<n_   
{ yaiw|j`A
 
oSavedFile = new RandomAccessFile(sName,"rw"); j`GL#J[wqQ  
this.nPos = nPos; &"(xd@V)]A  
oSavedFile.seek(nPos); Dl2`b">u  
} Bn 5]{Df  
=N5~iMorD-  
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public synchronized int write(byte[] b,int nStart,int nLen) Ps@a@d"83  
{ [/B$cH  
int n = -1; df=G}M(  
try{ &> Myf@  
oSavedFile.write(b,nStart,nLen); tCFXb6Cz  
n = nLen; '$@bTW  
} xWv@PqXD  
catch(IOException e) nwOT%@nw  
{ Lc<v4Bp  
e.printStackTrace (); @pcmVsIp  
} |2#)lGA  
{G:dhi  
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return n; o& g01t  
} L1FTh  
vR X_}`m8#  
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} 5E|y5|8fb  
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/* =i_ s#v[Y  
**SiteInfoBean.java 3dlL?+Y#  
*/ }IM*Vsk  
package NetFox; \t6k(5J  
tnv @`xBn  
8[zux4<m  
public class SiteInfoBean { 8<gYB$* S  
:T62_cFG  
z?NMQ8l|:6  
private String sSiteURL; //Site's URL noali96J  
private String sFilePath; //Saved File's Path zGfF.q}  
private String sFileName; //Saved File's Name ^W&qTSjh  
private int nSplitter; //Count of Splited Downloading File 9~ [Sio~  
>}& :y{z~  
VI{!ZD]  
public SiteInfoBean() @2>A\0U  
{//nSplitter的缺省值为5 k E^%w?C  
//default value of nSplitter is 5 Sn(e@|!G  
this("","","",5); S?ypka"L  
} '&XL|_Iq  
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Y8c#"vm(  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) WInfn f+'  
{ :qfP>Ok  
sSiteURL= sURL; UMcQqV+vT  
sFilePath = sPath; 8F?6Aq1B  
sFileName = sName; F/91Es  
this.nSplitter = nSpiltter; l[Hgh,  
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} gj(|#n5C  
Fx6c*KNX3  
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public String getSSiteURL() - '<K_e
;  
{ I?2S{]!?  
return sSiteURL; cPFs K*w  
} p_^Jr*Mv  
r#svj*dn  
4f)B@A-  
public void setSSiteURL(String value) g4Y1*`}2f  
{ b4Y<  
sSiteURL = value; 4=BIYC"Lu  
} q5@N//<DNN  
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#qx$ p  
public String getSFilePath() 2P`Z>_  
{ :5YL!D/&  
return sFilePath; DZ-2Z@{PX  
} ]Alv5?E60  
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public void setSFilePath(String value) 9L2]PU v  
{ } D'pyTf[  
sFilePath = value; AQx:}PO  
} z(00"ei  
F(!9;O5J]  
.paKV"LJ  
public String getSFileName() V8Lp%*(3  
{ $,@PY5r  
return sFileName; DW@|H  
}

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F gi&CJ8Q  
|n*nByL/  
public void setSFileName(String value) @%aU)YDwi  
{ ZOAHM1ci  
sFileName = value; +D3w2C
 
} -nHt6AbqP  
HX)oN8  
{*BZ;Xh\8  
public int getNSplitter() nzcXL =^r3  
{  z(YzK  
return nSplitter; d~0k}|>  
} (dH "b *  
8zI*<RX.Q  
/
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public void setNSplitter(int nCount) ;2k!K
W@  
{ o)V@|i0Js  
nSplitter = nCount; Z9)-kRQz=r  
} R^hlfKnt  
} m@,u&9K  
;4MC/Q/  
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/* 3i*HwEh  
**Utility.java ~x-"?K  
*/ D&dh>Pe1;  
package NetFox; ^t2b`n60  
6E)emFkQ  
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public class Utility { z^FJ  
f>!H<4 ]  
+u[^
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public Utility() Sc.@u3  
{ 1_=I\zx(  
"hbCP4  
#n_gry!5  
} |7$Q'3V  
B-1Kfc  
//线程睡眠 D;Bij=  
public static void sleep(int nSecond) Qo5yfdR  
{ -$A >b8  
try{ 4#Bzq3,|  
Thread.sleep(nSecond); X$Y\/|!z  
} kgv29j?k;  
catch(Exception e) _?I6[Mz  
{ 2gN78
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e.printStackTrace (); .rcXx
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} KHTRoXt  
} 

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<K:L.c!  
//日志 {Qf/.[  
public static void log(String sMsg) 9<|nJt  
{ B>kVJK`X  
System.err.println(sMsg); !r#36kO  
} f;`7}7C  
2Kmnt(>  
riu_^!"Z_  
public static void log(int sMsg) ~p!=w#/  
{ !^x;4@Ejm  
System.err.println(sMsg); d(_;@%p1X  
} j9d^8)O,  
} 03?7kAI  
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8=-/0y9,  
/* [W8"Mc|ve  
**TestMethod.java kZK1{  
*/ KlGmO;k  
package NetFox;  84g8$~M  
B
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] :.  
public class TestMethod { r}4  
e`eh;@9p  
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public TestMethod() uE ^uP@d  
{ ///xx/weblogic60b2_win.exe Swxur+hfH  
try{ 9
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); #ULzh&yO  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 9$WA<1PK+  
SiteFileFetch fileFetch = new SiteFileFetch(bean); #PGpB5vnaA  
fileFetch.start(); ( d1ho=  
} "+Kp8n6  
catch(Exception e){e.printStackTrace ();} 6 9s%  
zLSha\X  
 5?34<B  
} 5@nvcCp  
.)
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(v0i]1ly[  
public static void main(String[] args) eAK=ylF;  
{ g?gF*^_0  
new TestMethod(); C>*1f|<  
} Blox~=cW  
} tL\L4>^7T  
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