http断点续传简单实现（java)

/* U\y];\~H  
**SiteFileFetch.java 5A/G?  
*/ H;}V`}c
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package NetFox; K%>uSS?  
import java.io.*; 9xC,i )  
import java.net.*; ZYrXav<  
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public class SiteFileFetch extends Thread { 0,nDyTS^  
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SiteInfoBean siteInfoBean = null; //文件信息Bean iU{F\>  
long[] nStartPos; //开始位置 c0u!V+V%  
long[] nEndPos; //结束位置 f>5{SoM  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 $
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long nFileLength; //文件长度 <O>r e3s  
boolean bFirst = true; //是否第一次取文件 9>qR6k?  
boolean bStop = false; //停止标志 waW2$9O  
File tmpFile; //文件下载的临时信息 A5+vzu^  
DataOutputStream output; //输出到文件的输出流 z:|4S@9  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） zO2Z\E'%.  
public SiteFileFetch(SiteInfoBean bean) throws IOException Zo22se0)  
{ nvxftbfE^D  
siteInfoBean = bean; 8MM#q+8  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Tul_/`An  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); |~CN]N  
if(tmpFile.exists ()) ;58l_ue  
{ 7f'9Dm`  
bFirst = false; RT8xU;   
read_nPos(); X&t)S?eCos  
} 2Q)"~3  
else rFSLTbTf  
{ *8fnxWR  
nStartPos = new long[bean.getNSplitter()]; @P4fR7  
nEndPos = new long[bean.getNSplitter()]; Tl%#N"  
} :p(3Ap2TY  
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} Ej ip%m  
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public void run() %.BbPR7?h  
{ a{QHv0goG  
//获得文件长度 %s%v|HDs  
//分割文件 8k]'P*9ulz  
//实例FileSplitterFetch r@H<@Vuc  
//启动FileSplitterFetch线程 Zk)]=<H  
//等待子线程返回 fnG&29x  
try{ I7nt<l!  
if(bFirst) \D<rT)Tl  
{ ~a4htj  
nFileLength = getFileSize(); ioIUIp+B~u  
if(nFileLength == -1) Z'>Xn^  
{ WsTbqR)W%  
System.err.println("File Length is not known!"); qXkc~{W_  
} HjbC>*  
else if(nFileLength == -2) 0~H(GG$VH  
{ k;R*mg*K  
System.err.println("File is not access!"); Ti!j  
} QSW62]=vV  
else /);cl;"  
{ f:GZb?Wyd  
for(int i=0;i<nStartPos.length;i++) dOqn0Z  
{ DHW;*A-  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); DT8|2"H  
} KO<Yc`Fs  
for(int i=0;i<nEndPos.length-1;i++) H ZIJKk(  
{ 3lqR(Hh3  
nEndPos = nStartPos[i+1]; V{O,O,*  
} 9Y- Sqk+  
nEndPos[nEndPos.length-1] = nFileLength; mrX3/e  
} Di<KRg1W]}  
} G?{BVWtl}  
l&(,$RmYp  
5u MP31  
//启动子线程 4$+1jjC]>~  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 8=FP92X  
for(int i=0;i<nStartPos.length;i++) p-GlGEt_X  
{ -]~&Pi|  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #{1w#Iz;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), "@RLS~Ej  
nStartPos,nEndPos,i); aIpDf|~  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); D:e9609  
fileSplitterFetch.start(); t;TMD\BU  
} zy~vw6vu  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ^1BQejD  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); u{,e8. Z  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Aj#CB.y  
nEndPos = " + nFileLength); 3gaijVN  
// fileSplitterFetch[nPos.length-1].start(); xN:ih*+,v  
Vz!W(+  
!krbGpTVH  
//等待子线程结束 ce\]o^4  
//int count = 0; p3`'i  
//是否结束while循环 b{=2#J-  
boolean breakWhile = false; 8 qt,sU  
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while(!bStop) h!?7I=p~#  
{ 9Ruj_U  
write_nPos(); ;"hED:z6%  
Utility.sleep(500); +u#;k!B/>  
breakWhile = true; d_BECx<\  
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^]3Y11sI  
for(int i=0;i<nStartPos.length;i++) rP>iPDf  
{ 5m!FtHvm1  
if(!fileSplitterFetch.bDownOver) //nR
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{ G4vXPx%a8  
breakWhile = false; A,{X<mLFb  
break; `$\g8Mo  
} 4pq@o  
} X(U CN0#  
if(breakWhile) 1@6dHFA`o  
break;  /L'r L  
v=EV5#A  
0
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//count++; qvy
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//if(count>4) cu5Yvp  
// siteStop(); "jH=O(37  
} "G-} wt+P  
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L!Iu\_{q  
System.err.println("文件下载结束！"); .p NWd  
} Fd*)1FQKT  
catch(Exception e){e.printStackTrace ();} <[ />M  
} :^tw!U%y1  
j-8v$0'  
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//获得文件长度 SCs@Q  
public long getFileSize() T3,"g=  
{ 2`tdH|Z`  
int nFileLength = -1; 1O>wXq7q  
try{ Xp@8vu  
URL url = new URL(siteInfoBean.getSSiteURL()); A9' [x7N  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _]a8lr+_-  
httpConnection.setRequestProperty("User-Agent","NetFox"); T&c0j(  
=T;>$&qs  
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int responseCode=httpConnection.getResponseCode(); ^AkVmsv;;  
if(responseCode>=400) mD{<Lp=  
{ DvCs 5  
processErrorCode(responseCode); #5-5N5-1  
return -2; //-2 represent access is error -B-?z?+(O  
} YjN2 ,Xi  
]fvU}4!  
4nQk*:p(X  
String sHeader; i_Dv+^&zV  
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v!n\A}^:  
for(int i=1;;i++) 9otA5I^v  
{ wegu1Ny  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ~G|u
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//Utility.log(in.readLine()); SN+B8*!  
sHeader=httpConnection.getHeaderFieldKey(i); bCr) 3,  
if(sHeader!=null) _xT=AF9~o  
{ S*-n%D0q5  
if(sHeader.equals("Content-Length")) ,e{(r0  
{ 83~ Gu[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); DG,CL8bv  
break; V#["Z}  
} \]ouQR.t@\  
} z/6/   
else eIBHAdU+g/  
break; 9v>BP`Mg  
} EN/>f=%  
} @ c,KK~{  
catch(IOException e){e.printStackTrace ();} Bf33%I~  
catch(Exception e){e.printStackTrace ();} [,[;'::=o4  
}6ObQa43  
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Utility.log(nFileLength); F4'g}yOLd  
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return nFileLength; $Y.Z>I;  
} 7OY<*ny  
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%  
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//保存下载信息（文件指针位置） wv0d"PKTS  
private void write_nPos() SFCKD/8  
{ jiQJ{yY  
try{ 0f~7n*XH  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 1T:M?N8J  
output.writeInt(nStartPos.length); \?uaHX`1  
for(int i=0;i<nStartPos.length;i++) I;H6E  
{ dzJ\+ @4  
// output.writeLong(nPos); {* S8n09v  
output.writeLong(fileSplitterFetch.nStartPos); 8Q&.S)hrN  
output.writeLong(fileSplitterFetch.nEndPos); !T;*F%G9  
} PkA_uDhw  
output.close(); y+xw`gR:  
} 0!X;C!v;  
catch(IOException e){e.printStackTrace ();} H%
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catch(Exception e){e.printStackTrace ();} i bAZ*I  
} Ncr38~;w  
^% y<7>%  
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//读取保存的下载信息（文件指针位置） ^DVj_&~  
private void read_nPos() d'ddxT$GG  
{ ;AyE(|U+  
try{ [=M0%"  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); F[PIo7?K  
int nCount = input.readInt(); \l!^6G|c  
nStartPos = new long[nCount]; \`?#V xz  
nEndPos = new long[nCount]; .3WDtVE  
for(int i=0;i<nStartPos.length;i++) EWuuNf  
{
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nStartPos = input.readLong(); _/;k;$gDp  
nEndPos = input.readLong(); &'`q&U1x  
} :N03$Tvl  
input.close(); M`IiK+IoU  
} Trd/\tX#v&  
catch(IOException e){e.printStackTrace ();} ngF5ywIG  
catch(Exception e){e.printStackTrace ();} sute%6yM  
} O%?TxzX;  
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private void processErrorCode(int nErrorCode) G8xM]'y  
{ v~^c-
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System.err.println("Error Code : " + nErrorCode); ?^]29p_  
} &atT7m  
PZ5BtDm  

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//停止文件下载 8BZTHlUB  
public void siteStop() 9F+i+(\,b  
{ B.wihJVDg  
bStop = true; V_Z~$  
for(int i=0;i<nStartPos.length;i++) ;\(Wz5Ok&J  
fileSplitterFetch.splitterStop(); bg.f';C  
?DPNa  
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} :NB|r  
} v%RcwVt|  
//负责部分文件的抓取 vt{s"\f  
**FileSplitterFetch.java ;0*T7l  
*/ 9y=$|"<(  
package NetFox; *o]Q<
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{SH+lX0]{  
import java.io.*; Z9-HQ5>  
import java.net.*; mq~rD)T  
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5  
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public class FileSplitterFetch extends Thread { qc^u%  
{2kw*^,l  

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String sURL; //File URL 0{|ib !  
long nStartPos; //File Snippet Start Position ?^iX%   
long nEndPos; //File Snippet End Position z9mmZqhK\  
int nThreadID; //Thread's ID gs;3NW  
boolean bDownOver = false; //Downing is over z_fR?~$N2  
boolean bStop = false; //Stop identical RFF&-M]  
FileAccessI fileAccessI = null; //File Access interface `P;fD/I  
n]&/?6}  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {XYv&K  
{ d;(&_;  
this.sURL = sURL; s_Y1rD*B  
this.nStartPos = nStart; `jY*0{  
this.nEndPos = nEnd; :UjHP}s  
nThreadID = id; 9G(.=aOj,  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Hb&-pR@e\?  
} 3md yY\+&  
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public void run() p"^^9'`=  
{ "B`yk/GM]  
while(nStartPos < nEndPos && !bStop) e6s-;
 
{ >o{(f  
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try{ dt
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URL url = new URL(sURL); +gb2>fei&  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); l'YpSO~l7  
httpConnection.setRequestProperty("User-Agent","NetFox"); @W3fKF9*R  
String sProperty = "bytes="+nStartPos+"-"; r1:S8RT;H5  
httpConnection.setRequestProperty("RANGE",sProperty); V^Wo%e7#u[  
Utility.log(sProperty); Alh"G6  
b6=.6?H@4f  
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InputStream input = httpConnection.getInputStream(); IQ$l!)  
//logResponseHead(httpConnection); Nx4_Oc^hY  
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byte[] b = new byte[1024]; Zab5"JR  
int nRead; Nt42v  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) w91gM*A  
{ s+?r4t3H!  
nStartPos += fileAccessI.write(b,0,nRead); pE>~F  
//if(nThreadID == 1) -05zcIVo  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); GRz`fO  
} `T $lTP  
qe!`LeT#  
rC~hjViG.  
Utility.log("Thread " + nThreadID + " is over!"); ~X;r}l=k<  
bDownOver = true; +) 2c\1  
//nPos = fileAccessI.write (b,0,nRead); yBO88rfh
>  
} Tysh~C|1  
catch(Exception e){e.printStackTrace ();} 4&/u1u0  
} SZJ~ktXC-V  
} Y<Y5HI"  
#tG/{R  
Q%4>okj,  
//打印回应的头信息 ) ^PY-~o[  
public void logResponseHead(HttpURLConnection con) N3E Qq~lX  
{ MO)N0{.b  
for(int i=1;;i++) o?uTL>Zin  
{ :pQZ)bF  
String header=con.getHeaderFieldKey(i); F;yq/e#Q  
if(header!=null) #9z\Wblr  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ry}CND(nB  
Utility.log(header+" : "+con.getHeaderField(header)); qNER 6  
else oPRvd_~  
break; 0}$",M!p  
} #:L|-_=a  
} Mvoi   
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public void splitterStop() l<)(iU  
{ ]od]S8$5  
bStop = true; R^P~iAO  
} [0N==Ym1  
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} 1R9hA7y&,/  
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7)G- EAF  
/*  ~d_Z?Z  
**FileAccess.java s&Y~48{  
*//文件访问(定位，写) ;hNnF&l  
package NetFox; 4\<[y]pv  
import java.io.*; `Q6@,-(3  
HB`u@9le  
mzTF2K  
public class FileAccessI implements Serializable{ [>&Nhn0iY  
'#[U7(lIQ  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 A:[La#h|p  
RandomAccessFile oSavedFile; DIodQkF  
long nPos; iOm1U_S  
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d  
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public FileAccessI() throws IOException G\tTwX4  
{ 
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this("",0); ^Qz8`1`;Z  
} vjaIFyj  
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public FileAccessI(String sName,long nPos) throws IOException & PrV+Lv  
{ =K{$?%"  
oSavedFile = new RandomAccessFile(sName,"rw"); YFOK%7K  
this.nPos = nPos; -QCo]:cp  
oSavedFile.seek(nPos); 1t=Y+|vA9  
}
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bG67TWY)  
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public synchronized int write(byte[] b,int nStart,int nLen) V^nYG$si  
{ ~;#J&V@D  
int n = -1; \ntmD?kA  
try{ )ruC_)  
oSavedFile.write(b,nStart,nLen); r|cl6s!P  
n = nLen; U#1T HO`  
} `zRgP#  
catch(IOException e) VkhZt7]K}B  
{ d|]F^DDuI  
e.printStackTrace (); ukv _bw  
} ,XCC#F(d1  
=PAvPj&}e  
8dq{.B?  
return n; 016l$K4  
} /L'm@8  
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} 1K^blOLXe  

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DSYtj}>  
/* 1F-o3\  
**SiteInfoBean.java k=H{gt  
*/ |~hSK  
package NetFox; *RUB`tEL  
?2OT:/I,  
##BMh!  
public class SiteInfoBean { 1gts=g.  
qqQnL[`)C  
FyJI@PZdI-  
private String sSiteURL; //Site's URL Mkko1T=6  
private String sFilePath; //Saved File's Path @)m[:n  
private String sFileName; //Saved File's Name UP 1Y3  
private int nSplitter; //Count of Splited Downloading File W"AWhi{h  
2:MB u5**  
3X*;.'#Z  
public SiteInfoBean() f( hK>H  
{//nSplitter的缺省值为5 fo&q/;l\  
//default value of nSplitter is 5 !0c7nzjm  
this("","","",5); .\X/o!xC  
} zA9N<0[]o  
6(B0gBCId  
9c9-1iS  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) vLDMa>  
{ 2V/A%  
sSiteURL= sURL; ;gy_Qf2U  
sFilePath = sPath; HI#}M|4n  
sFileName = sName; 6g29!F`y  
this.nSplitter = nSpiltter;  Usk@{  
je9[S_Z:Y  
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} EK_NN<So#  
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public String getSSiteURL() KCq qwGM  
{ Lg|j0-"N  
return sSiteURL; `x~k}  
} p*_g0_^  
HGfYL')Z  
MG[?C2KA/  
public void setSSiteURL(String value) z 4Qz9#*"^  
{ B{H;
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sSiteURL = value; JVwYV5-O<0  
} E0\ '  
qc|;qPj   
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public String getSFilePath() - 4'yp  
{ !w]!\H  
return sFilePath; y1cAw   
} &E.0!BuqV  
*W y0hnr;]  
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public void setSFilePath(String value) _D1bR7  
{ ,[,+ _A  
sFilePath = value; yx3M0Qo  
} g~h`wv'  
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aW
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public String getSFileName() YNn,{Xi  
{ ymY,*Rb  
return sFileName; hZY+dHa]  
} kWjCSC>jA  
Au#(guvm  
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public void setSFileName(String value) Ooc,R(  
{ Zla5$GM  
sFileName = value; Ag }hyIl  
} lEQ63)Z  
zu(/c  
Ec8Y}C,{7<  
public int getNSplitter() cInzwdh7  
{ BqvOi~l  
return nSplitter; )_NQ*m  
} FfI$3:9  
m=z-}T5y!T  
-kq=W_  
public void setNSplitter(int nCount) DC]FY|ff  
{ Kqce
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nSplitter = nCount; !\JG]2 \  
} OQ 5{#  
} 1{_tV^3@  
fxI>FhU_  
.ZxSJ"Rk  
/* ;.V5:,&  
**Utility.java KNC!T@O|{#  
*/ ;x@9@6_  
package NetFox; 9x?" %b  
-x_b^)x~b7  
)6PZ.s/F6p  
public class Utility { bnWIB+%_  
^>.?kh9z  
t#&^ -;  
public Utility() o(]kI?
`  
{ }=^YLu=  
$
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F&lWO!4  
} q!7z4Cn  
ORs<<H.d  
//线程睡眠 LV0g *ng  
public static void sleep(int nSecond) ZWG$MFEjl  
{ ]d9;YVAU  
try{ lD6hL8[  
Thread.sleep(nSecond); oPk2ac  
} 6f?5/hq  
catch(Exception e) !a[ voUS  
{ 'dQ2"x?4  
e.printStackTrace ();
:o*{.  
} NVS U)#  
} )$P!7$C-  
(jPN+yQ  
//日志 `dMOBYV  
public static void log(String sMsg) g`y >)N/  
{ }LM^>M%  
System.err.println(sMsg); KAjKv_6=g  
} Fq&@dxN3  
j{7_p$JM  
bo 
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public static void log(int sMsg) l4O}>#  
{ I=x  
System.err.println(sMsg); pHsp]a  
} %~4R)bsJ'  
} 7xVI,\qV  
$A
7[?Ai ?  
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/* M86
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**TestMethod.java @_FL,AC&m  
*/ ykRKZYfsw(  
package NetFox; 4^w>An6  
RB\>$D  
/]>&OSV  
public class TestMethod { hnvn&{|  
mz+>rc  
xaoaZ3Ko  
public TestMethod()
x|U]x  
{ ///xx/weblogic60b2_win.exe ti`
z:8n7  
try{ m589C+7  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); )cUc}Avg}  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); bNFX+GA/  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ?)",}XL6  
fileFetch.start(); Vd)iv\a  
} e&8pTD3  
catch(Exception e){e.printStackTrace ();} S@Yb)">ZQ  
JXftQOn  
ah"2^x  
} UQPd@IVu6  
aPcO9  
Dd!MG'%hlb  
public static void main(String[] args) H6/@loO!Xy  
{ hNyYk(t^  
new TestMethod(); @xtcjB9  
} L G,XhN  
} =Q.2:*d.  
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