http断点续传简单实现（java)

/* ;+S2

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**SiteFileFetch.java -fb1cv~N  
*/ Na~g*)uT$  
package NetFox; ]$*$0  
import java.io.*;
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import java.net.*; 113Z@F  
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public class SiteFileFetch extends Thread { _Ym&UY.u#  
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SiteInfoBean siteInfoBean = null; //文件信息Bean MsN2A6|33  
long[] nStartPos; //开始位置 &.|;yt%v  
long[] nEndPos; //结束位置 /ig^7+#  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 9$B)hrJo  
long nFileLength; //文件长度 44Seq  
boolean bFirst = true; //是否第一次取文件 ;`X`c  
boolean bStop = false; //停止标志 31 KDeFg  
File tmpFile; //文件下载的临时信息 yb@X*PW
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DataOutputStream output; //输出到文件的输出流 ~$ cm9>  
*#X+Gngo  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类）
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public SiteFileFetch(SiteInfoBean bean) throws IOException ;Xnk+  
{ `R4W4h'I  
siteInfoBean = bean; :epitpJ  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); .#:@cP~v  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); b;&Yw-\nZ;  
if(tmpFile.exists ()) mI_ 6f~  
{ \?5[RR  
bFirst = false; qiwQUm{  
read_nPos(); HQ-N!pf9  
} >X@.f1/5X  
else $S"zxEJJ Y  
{ VfJX<e=k  
nStartPos = new long[bean.getNSplitter()]; S[\cT:{OE  
nEndPos = new long[bean.getNSplitter()]; (_s!,QUe  
} Q@3ld6y  
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} l:kE^=6  
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public void run() 2_ZHJ,r   
{ A-@-?AR  
//获得文件长度 MRxo|A{  
//分割文件 ] BP^.N=  
//实例FileSplitterFetch K7d1(.  
//启动FileSplitterFetch线程 lN]X2 4t  
//等待子线程返回 7\Yq]:;O  
try{ ni02
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if(bFirst) <iY 9cV|}3  
{ SquqaX+<  
nFileLength = getFileSize(); QtO[g  
if(nFileLength == -1) nu1w:  
{ /fcwz5~  
System.err.println("File Length is not known!"); vp9E}ga  
} z;@S_0M,Z  
else if(nFileLength == -2) F0o18k_"  
{ hGaYQgGq  
System.err.println("File is not access!"); !UPAEA  
} p_kTLNZd9  
else ::Ve,-0  
{ T J"{nB  
for(int i=0;i<nStartPos.length;i++) a}Iz  
{ ^,\se9=(  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); E`Zh\u)  
} rO2PbF3  
for(int i=0;i<nEndPos.length-1;i++) y5opdIaT  
{ nh_xbo5L[  
nEndPos = nStartPos[i+1]; F\$}8
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} )-6[Bw  
nEndPos[nEndPos.length-1] = nFileLength; N'1[t  
} _d"Y6 0  
} l>Oe ,`9O  
(l,YI"TzT  
l=.InSuLT  
//启动子线程 9R<J$e  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; >5YYij5Aj  
for(int i=0;i<nStartPos.length;i++) N6 Cc%,  
{ =?QQb>  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), aG&kl O>m  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Pp")hFx  
nStartPos,nEndPos,i); W71#N
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _[6+FdS],  
fileSplitterFetch.start(); yyYbB]D  
} L``mF(R^  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 1</t #r  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 6(RqR  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", .M#>@~XR  
nEndPos = " + nFileLength); Ay. q
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// fileSplitterFetch[nPos.length-1].start(); 2LK*Cv[  
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^*T{-U'  
//等待子线程结束 kO O~%|1CP  
//int count = 0; a~+
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//是否结束while循环 {hp
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boolean breakWhile = false; SX94,5 _Q  
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while(!bStop) \y+F!;IxL  
{ ?@7|Q/  
write_nPos(); E~U|v'GCd  
Utility.sleep(500); CMB$RLf  
breakWhile = true; <UHf7:0V  
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for(int i=0;i<nStartPos.length;i++) jfhDi6N  
{ `Y9}5p  
if(!fileSplitterFetch.bDownOver) >@\?\!Go  
{ h.0&)t\q"  
breakWhile = false; GoGgw]h>x  
break; gG|1$  
} v8M#
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} YV+dUvz  
if(breakWhile) rY+1s^F  
break; |U
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//count++; H_^u_%:e  
//if(count>4) N`:bvr  
// siteStop(); hndRgCo  
} ]fmfX  
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System.err.println("文件下载结束！"); , X+(wp  
} 9O_N iu0  
catch(Exception e){e.printStackTrace ();} i2c<q0u  
} X
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ho=]'MS|  
#GJh:#tt^  
//获得文件长度 0X6o  
public long getFileSize() _\6(4a`,  
{ c3BL2>c  
int nFileLength = -1; RlL,eU$CS  
try{ 73<yrBxp  
URL url = new URL(siteInfoBean.getSSiteURL()); =f|a?j,f~  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ${2fr&Tp  
httpConnection.setRequestProperty("User-Agent","NetFox"); |ZzBCL8q  
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int responseCode=httpConnection.getResponseCode(); IH}L1i A)  
if(responseCode>=400) J4X35H=Z  
{ 
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processErrorCode(responseCode); 9D21e(7X  
return -2; //-2 represent access is error vGDo?X~#o  
} w\4m-Z{  
1
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1MSu]) W  
String sHeader; H|O}Dsj  
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for(int i=1;;i++) <rF  
{ #+\G- =-  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); r/f;\w7  
//Utility.log(in.readLine()); xnOlV  
sHeader=httpConnection.getHeaderFieldKey(i); ';F][x5j  
if(sHeader!=null) +.cv,1Vx  
{ :Aw VeX@  
if(sHeader.equals("Content-Length")) (v}:  
{ E]Q)pZ{Jb  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); +Eg# 8/q  
break; mws.)  
} @xEQ<g  
} .EwK>ro4  
else 4N&}hOM'S  
break; GAKJc\o  
} nt6"}vO  
} Y}Uw7\e  
catch(IOException e){e.printStackTrace ();} lla96\R  
catch(Exception e){e.printStackTrace ();} {'(8<n5
7  
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Utility.log(nFileLength); @dNbL}qQ  
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return nFileLength; +l(}5(wc  
} W!*vO>^1W  
)
3  
+L6d$+  
//保存下载信息（文件指针位置） =B1!em|  
private void write_nPos() 9`AQsZ2  
{ S8l+WF4q  
try{ e<K=Q$U.  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 9 pn1d.  
output.writeInt(nStartPos.length); ;f Gi5=-  
for(int i=0;i<nStartPos.length;i++) XJ9>a-{  
{ ~m7+^c@,  
// output.writeLong(nPos); f&'md  
output.writeLong(fileSplitterFetch.nStartPos); wlJ1,)n^2  
output.writeLong(fileSplitterFetch.nEndPos); $ }53f'QjW  
} 4.TG&IQ nN  
output.close(); ff0,K#-  
} F<[8!^l(z  
catch(IOException e){e.printStackTrace ();} uY,FugWbl  
catch(Exception e){e.printStackTrace ();} Eh+lLtZ  
} dq2v[?*R  
_PF><ODX2  
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//读取保存的下载信息（文件指针位置） aO1cd_d6x_  
private void read_nPos() \]K-<&f  
{ /Q-!><riD  
try{ Hg4Ut/0  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Ts\7)6|F  
int nCount = input.readInt(); W3b\LnUa  
nStartPos = new long[nCount]; 0Ko,S(M_  
nEndPos = new long[nCount]; @OpcS>:R  
for(int i=0;i<nStartPos.length;i++) F3q5!1  
{ 8Bhng;jX  
nStartPos = input.readLong(); L<:ya  
nEndPos = input.readLong(); F&0rI8Nr  
} t%)L8%Jr  
input.close(); ="`y<J P  
} -}%zus5  
catch(IOException e){e.printStackTrace ();} -?uwlpm#  
catch(Exception e){e.printStackTrace ();}
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} bWqGypq4  
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private void processErrorCode(int nErrorCode) x\*5A,w{c]  
{ |l9AgwDg  
System.err.println("Error Code : " + nErrorCode); =xgW$c/yB  
} qcK)J/K"  
8]O|$8'"  
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//停止文件下载 +wmfl:\^{H  
public void siteStop() Z"n]y4h  
{  *q^'%'  
bStop = true; '&"7(8E} *  
for(int i=0;i<nStartPos.length;i++) P5N"7/PfW  
fileSplitterFetch.splitterStop(); 9DIGK\  
>@t]M`#&h
 
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} $1axZ~8sS  
} "PX~Yc  
//负责部分文件的抓取 D!:Qy@Zw  
**FileSplitterFetch.java <Sz9: hg-  
*/ 8'zwyd3  
package NetFox; B$\5=[U  
-/h$Yb  
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import java.io.*; zRe0z2  
import java.net.*; }RD,JgmV  
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public class FileSplitterFetch extends Thread { lY6U$*9c  

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)&*&ZL0  
String sURL; //File URL ztu N0}'  
long nStartPos; //File Snippet Start Position *QrTZ$\C  
long nEndPos; //File Snippet End Position 2hquE_1S[w  
int nThreadID; //Thread's ID 9{+B lNZ  
boolean bDownOver = false; //Downing is over f1Rm9
``  
boolean bStop = false; //Stop identical _mcD*V  
FileAccessI fileAccessI = null; //File Access interface " I:j a7  
6CCM7  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException u\6:Txqq  
{ IuRKj8J)o  
this.sURL = sURL; !W8$-iq  
this.nStartPos = nStart; gPDc6{/C<  
this.nEndPos = nEnd; ETYw  
nThreadID = id; 63ht|$G  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Cfa?LgSz  
}  ~UXW  
x H\5T!  
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public void run() YrA#NTB_o  
{ 92XzbbLp  
while(nStartPos < nEndPos && !bStop) Uh*V>HA#  
{ xqIt?v2c  
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!MoGdI-<r[  
try{ X5=Dc+  
URL url = new URL(sURL); )fv0H&g  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); mL ]zkD_  
httpConnection.setRequestProperty("User-Agent","NetFox"); |_Z(}% <o  
String sProperty = "bytes="+nStartPos+"-"; m\[r6t]V  
httpConnection.setRequestProperty("RANGE",sProperty); jeC3}BL}  
Utility.log(sProperty); |R DPx6!V  
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InputStream input = httpConnection.getInputStream(); Kh}#At^C8e  
//logResponseHead(httpConnection); ~gmj/PQ0  
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=rGjOb3+  
byte[] b = new byte[1024]; BH0].-)[y!  
int nRead; hgLwxJu  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) i_Ab0vye  
{ rOEk%kJ  
nStartPos += fileAccessI.write(b,0,nRead); #zyEN+  
//if(nThreadID == 1) q0&g.=;  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); *v_+a:  
} d@JjqE[  
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Utility.log("Thread " + nThreadID + " is over!"); +QGZ2_vW  
bDownOver = true; :'|%~&J  
//nPos = fileAccessI.write (b,0,nRead); 3{O^q/R  
} ~*@UQ9*p#  
catch(Exception e){e.printStackTrace ();} by (xv0v;  
} q ^Un,h64t  
} pqmtN*zV  
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8GgZAu'X  
//打印回应的头信息 \]1qAF
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public void logResponseHead(HttpURLConnection con) 2x<,R/}  
{ _8P0iC8Zg#  
for(int i=1;;i++) p"\
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{ %F_)!M;x  
String header=con.getHeaderFieldKey(i); @(<C{  
if(header!=null) rozp  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Fuq ;4UcbL  
Utility.log(header+" : "+con.getHeaderField(header)); f~ kz=R=  
else fP# !ywgr%  
break; |WwC@3)  
} WdI9))J2S  
} &c>%E%!"  
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public void splitterStop() |C"(K-do  
{ !Lkk1zo  
bStop = true; c_wvuKa  
} -|V
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!1(*D*31  
} Wg{ 9X#|  
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/* 4,EX2  
**FileAccess.java YOOcHo.F  
*//文件访问(定位，写) F-R5Ib-F*A  
package NetFox; L;RHshTy  
import java.io.*; Wdk]>w 'L  
0nr5(4h  
]?S@g'Jd0Q  
public class FileAccessI implements Serializable{ ibP IT!5c  
LUaOp "  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 S$N!Dj@e;  
RandomAccessFile oSavedFile; CZE!@1"<{  
long nPos; j#U,zsv:  
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public FileAccessI() throws IOException z9!OzGtIR  
{ +|x{?%
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this("",0); {V pko  
} mMvAA;  
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public FileAccessI(String sName,long nPos) throws IOException !"o\H(siT  
{ lMH~J8U3  
oSavedFile = new RandomAccessFile(sName,"rw"); w+r).PS}C  
this.nPos = nPos; XjdHH.) S  
oSavedFile.seek(nPos); (S4HU_,88  
} )dFPfu&HL  
<5^m`F5  
, @!X!L  
public synchronized int write(byte[] b,int nStart,int nLen) ;l1.jQh  
{ =j{tFxJ  
int n = -1; ?"^{:~\N  
try{ [?hvx}  
oSavedFile.write(b,nStart,nLen); -Lq2K3JHyn  
n = nLen; ,"KfZf;?  
} ZyDNtX%  
catch(IOException e) o='A1P  
{ alB'l  
e.printStackTrace (); }#-@5["-X  
} xticC>  
}O>4XFj  
W9pY=9]p+  
return n; ya{`gjIlW  
} #0vda'q=j  
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} kz1#"8Zd!  
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?  
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/* NJ+$3n om  
**SiteInfoBean.java 4H(8BNgzV  
*/ G<=I\T'g;  
package NetFox; h]L.6G|hEN  
$,J}w%A  
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public class SiteInfoBean { p^*a>d:d]  
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iLIb-d?!a&  
private String sSiteURL; //Site's URL 2J{vfF  
private String sFilePath; //Saved File's Path CuH4~6  
private String sFileName; //Saved File's Name OdZ/\_Z  
private int nSplitter; //Count of Splited Downloading File d,N6~?B  
qD4s?j-9  
U3z23LgA  
public SiteInfoBean() as]M%|/-I  
{//nSplitter的缺省值为5 Wh..QVv  
//default value of nSplitter is 5 (3mL!1\  
this("","","",5); |'1.ajxw  
} =.;ib6M  
?4U4o<   
Ahl&2f\  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Jw@X5-(Cp  
{ m3Wc};yE*Q  
sSiteURL= sURL; :d9GkC  
sFilePath = sPath; K<:%ofB"S  
sFileName = sName; sZCK?  
this.nSplitter = nSpiltter; |f @A-d X  
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2F
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} \fEG5/s}T  
x%r$/=  

3))CD,|  
public String getSSiteURL() h6?^rS8U  
{ j@(S7=^C6%  
return sSiteURL; 7Z`4Kdh .  
} Ar~/KRK  
:AFW=e@<  
EBW*v '  
public void setSSiteURL(String value) SQ> Yf\  
{ +58^{_k+%  
sSiteURL = value; Q2Ey RFT  
} )s^gT]"N  
]Ss63Vd  
9)]`le  
public String getSFilePath() Y\_mqd  
{ !PGCoI  
return sFilePath; 9C,gJp}P  
} {$[0YRNk u  
Cj3Xp~  
-M6vg4gf  
public void setSFilePath(String value) ";(m,if-  
{ jrN 5l1np  
sFilePath = value; !p+rU
?  
} cJq{;~  
.Qn
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ufR>*)_+  
public String getSFileName() .O0eSp|e  
{ 9-m_ e=jk6  
return sFileName; ,/Gp>Yqx  
} um]*nXIr  
2N &B  
:/=P6b;  
public void setSFileName(String value) l2Py2ZI-b  
{ ~oSA&v4V  
sFileName = value; lmoYQFkYP  
} '!Va9m*w7  
Fczia0@z  
AM!P?${a  
public int getNSplitter() ZT&[:>upR  
{ ZUB]qzmK  
return nSplitter; \ :@!rM  
} aRWj+[[7y  
%`G
}/"  
8sDw:wTC  
public void setNSplitter(int nCount) >/C,1}p[  
{ Ve[Kv07  
nSplitter = nCount; epk C'  
} nrpbQ(zI*  
} &JLKHwi/  
r H9}VA:h  
8_D:#i  
/* '2|mg<Ft  
**Utility.java L-|7 &  
*/ 2V9"{F?  
package NetFox; dXt@x8E  
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G
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public class Utility { Gqar5  
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public Utility() ABtv|0K  
{ 9Kz
}  
]Ah<kq2sk  
,+n{xI2  
} czo*_q%  
:NwFJc  
//线程睡眠 Q;2kbVWY  
public static void sleep(int nSecond) v'y<}U  
{ :,^x?'
HK  
try{ c&L|e$C]  
Thread.sleep(nSecond); &eg@ZnPn  
} hdH-VR4  
catch(Exception e) ",E$}= ,Z  
{ ^j_t{h)W(0  
e.printStackTrace (); t_X=x`f  
} +N:M;uTS  
} -S$Y0FDV  
9@p+g`o  
//日志 kvt"7;(  
public static void log(String sMsg) lS`VJA6l.  
{ Kv\uBMJNW  
System.err.println(sMsg); i'Q 4touy  
} /(ArA=#  
%Zu+=IZ  
\"=@uqar2  
public static void log(int sMsg) 1,G f;mcQ  
{ v|r#  
System.err.println(sMsg); ]M9r<x*  
} `>}e 5  
} K06&.>v_  
7;:Uv=  
jP"='6Vrw  
/* cLnvb!g'#  
**TestMethod.java {W#VUB  
*/ L{i|OK^e  
package NetFox; 3HmJixy  
RV+0C&0ff  
/3v`2=b  
public class TestMethod { |/35c0IM  
};;6706a  
y{\K: 
 
public TestMethod() 0NG<uZ  
{ ///xx/weblogic60b2_win.exe .Cf`D tK  
try{ $5/lU }To  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); z@em1W0?Z  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 4~/3MG  
SiteFileFetch fileFetch = new SiteFileFetch(bean); /F6=iHK(l  
fileFetch.start(); |;_uN q9  
} 8L*P!j9`EY  
catch(Exception e){e.printStackTrace ();} <O?UC/$)7  
:CAbGs:56  
eyGY8fF8$  
} g!`$bF=e  
n$T'gX#5  
xT$9M"  
public static void main(String[] args) PxHHh{y%c  
{ 2aUy1*aM  
new TestMethod(); m0k~8^L@f  
} `by\@xQ)  
} Xy(o0/7F9  
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