http断点续传简单实现（java)

/* )y*&&q   
**SiteFileFetch.java yO%^[c?  
*/ >=;-:  
package NetFox; g:Qq%'  
import java.io.*; }? / Blr  
import java.net.*; lz#.f,h  
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+ m-88  
public class SiteFileFetch extends Thread { #ay/VlD@  
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SiteInfoBean siteInfoBean = null; //文件信息Bean FJtmRPP[r  
long[] nStartPos; //开始位置 _`?cBu`  
long[] nEndPos; //结束位置 (yP1}?  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 kiM:(=5  
long nFileLength; //文件长度 LP#wE~K"b  
boolean bFirst = true; //是否第一次取文件 YXWDbr:JX  
boolean bStop = false; //停止标志 U|Fqna  
File tmpFile; //文件下载的临时信息 O00;0wu  
DataOutputStream output; //输出到文件的输出流 i&>^"_4rc  
}jCO@v;  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ({t^/b*8  
public SiteFileFetch(SiteInfoBean bean) throws IOException +=E\sEe  
{ \KhcNr?ja=  
siteInfoBean = bean; (_e[CqFu  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); i-v: %  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); n<8WjrK  
if(tmpFile.exists ()) =|E "  
{ &wK:R,~x6  
bFirst = false; ik(YJw'i7E  
read_nPos(); gW~T{+f  
} qK.(wFx  
else 68u?}8}  
{ A|f6H6UUx  
nStartPos = new long[bean.getNSplitter()]; <7U~0@<Y  
nEndPos = new long[bean.getNSplitter()]; b&[".ibN1  
} Bp7p X  
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} )v;O2z  
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public void run() ;9z|rWsF  
{ G%bv<_R  
//获得文件长度 n3~axRPO  
//分割文件 #b;?:.m\=  
//实例FileSplitterFetch w~6UOA8}  
//启动FileSplitterFetch线程 g0zzDv7~  
//等待子线程返回 Mrrpm%Y  
try{ >IaGa!4  
if(bFirst) oI
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{ 4aOz=/x2  
nFileLength = getFileSize(); !2!Zhw2u  
if(nFileLength == -1) 5]dlD #  
{ @lj|  
System.err.println("File Length is not known!"); `qhT  
} <h:xZtz  
else if(nFileLength == -2) nvrh7l9nX  
{ 7!AyLw  
System.err.println("File is not access!"); j<(E%KN3  
} 0V<kpC,4  
else kMVr[q,MEq  
{ 6ncwa<q5  
for(int i=0;i<nStartPos.length;i++) e& `"}^X;I  
{ _:9}RT?  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Py v>  
} v>`Fo[c  
for(int i=0;i<nEndPos.length-1;i++) 4O-LLH  
{ *MmH{!=  
nEndPos = nStartPos[i+1]; 5oG~Fc  
} nUj`#
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nEndPos[nEndPos.length-1] = nFileLength; Uwkxc  
} l3Zi]`@r  
} C%Lr3M;S'  
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//启动子线程 W_M#Gi/AL  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; X\;:aRDS  
for(int i=0;i<nStartPos.length;i++) l-%]f]>  
{ rgIWM"  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 9~W]D!m,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 8B*(P>  
nStartPos,nEndPos,i); _$AM=?P&  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); q{&c?l*2  
fileSplitterFetch.start(); oH=?1~e  
} D-{*3?x  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), gPCf+>X{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); aC}\`.Kb  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", jr)M],  
nEndPos = " + nFileLength); 4E.9CjN1>  
// fileSplitterFetch[nPos.length-1].start(); ^(:~8 h  
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l[i4\ CT  
//等待子线程结束 \#%GVru!  
//int count = 0; EFC+7L(j  
//是否结束while循环 qj_0 td$  
boolean breakWhile = false; 'zm5wqrkAd  
}MOXJb @  
op`9(=DJ]  
while(!bStop) %}TJr]'F  
{ "B:FSWM_-  
write_nPos(); E&cC2(w  
Utility.sleep(500); #@DJf  
breakWhile = true; TQck$&  
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9 3)fC  
for(int i=0;i<nStartPos.length;i++) ^Saf z8-3o  
{ *4 LS``  
if(!fileSplitterFetch.bDownOver) K[iAN;QCe%  
{ ]|!|3lQ  
breakWhile = false; }iKjef#J  
break; ~B{08%|oK  
} 7<WUjK|  
} LujLC&S  
if(breakWhile) < +
*  
break; =,zB|sjn  
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//count++; 0M;g&&mF  
//if(count>4) >s/_B//[  
// siteStop(); [;ZCq!)>  
} s]99'Q",  
.
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System.err.println("文件下载结束！"); `_cv& "K9f  
} -crMO57/  
catch(Exception e){e.printStackTrace ();} 3r+c&^  
} /b>xQ.G  
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//获得文件长度 'sIne>  
public long getFileSize() 8WV5'cX  
{ k9*U
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int nFileLength = -1; 9BZ B1oX  
try{ .pPuBJL]<  
URL url = new URL(siteInfoBean.getSSiteURL()); -}<Ru)  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wzy[sB274  
httpConnection.setRequestProperty("User-Agent","NetFox"); J#C4A]A  
@}6<,;|DQ  
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int responseCode=httpConnection.getResponseCode(); W)ug%@)  
if(responseCode>=400) 2 )o2d^^  
{ Ut2T:%m{  
processErrorCode(responseCode); 424iFc[  
return -2; //-2 represent access is error ykbfK$jz  
} ]CNPy$>*  
?<4pYEP  
b * \ oQ  
String sHeader; Ry}4MEq]  
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for(int i=1;;i++) =b*GV6b  
{ jo&j<3i  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); .t[u_tBL  
//Utility.log(in.readLine()); T+T)~!{%  
sHeader=httpConnection.getHeaderFieldKey(i); F1BvDplQ>G  
if(sHeader!=null) ]R\L~Kr  
{ mRAt5a#is  
if(sHeader.equals("Content-Length")) sT1k]duT  
{ ;R0LJApey  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Sydl[c pH$  
break; W3[>IH"+  
} 3M?O(oO  
} OP+*%$wR  
else
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break; u\ 7Y_`8  
} neu<zSS  
} CRCy)AS,t  
catch(IOException e){e.printStackTrace ();} uq[5 om"  
catch(Exception e){e.printStackTrace ();} iC hIW/H  
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Utility.log(nFileLength); |e!Y C iU  
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return nFileLength; ^|oI^"IQ=  
} afHRy:<+%  
rr
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.s4vJKK0  
//保存下载信息（文件指针位置） .BxQF  
private void write_nPos() 3}V (8  
{ <;#gcF[7>  
try{ +fY@q,`  
output = new DataOutputStream(new FileOutputStream(tmpFile)); MPnMLUB$\  
output.writeInt(nStartPos.length); *PlKl_nP6  
for(int i=0;i<nStartPos.length;i++) Y>3z
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{ ;Egl8Vhr  
// output.writeLong(nPos); ]0<K^OIY  
output.writeLong(fileSplitterFetch.nStartPos); %`pi*/(  
output.writeLong(fileSplitterFetch.nEndPos); ^! h3#4  
} Kn$t_7AF^  
output.close(); ?`Z:vqp>Z  
} *>?N>f"  
catch(IOException e){e.printStackTrace ();} %cDGs^lgA  
catch(Exception e){e.printStackTrace ();} Ndl{f=sjX-  
} 7./-|#  
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//读取保存的下载信息（文件指针位置） 
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private void read_nPos() mI<sf?.  
{ n}Eu^^d  
try{ 2?LPr  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); :mDOqlXW/  
int nCount = input.readInt(); 4/{pz$  
nStartPos = new long[nCount]; ,Vj&  
nEndPos = new long[nCount]; :55a9d1bL  
for(int i=0;i<nStartPos.length;i++) RLex#j  
{ 13 L&f\b  
nStartPos = input.readLong(); Z2*?a|3  
nEndPos = input.readLong(); >q?{'#i /  
} Iu0GOy*[  
input.close(); #l
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} AW\uE[kg  
catch(IOException e){e.printStackTrace ();} 2sgp$r  
catch(Exception e){e.printStackTrace ();} lAG@nh^  
} ;uc3_J]  
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?{ \7th37  
private void processErrorCode(int nErrorCode) id+EBVHAd  
{ Pbbi*&i  
System.err.println("Error Code : " + nErrorCode); Qt\:A!'jw  
} 9G6ZKqum  
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//停止文件下载 \;_tXb}F  
public void siteStop() L;g2ZoqIr0  
{ ^-Arfm%dn  
bStop = true; #a@jt  
for(int i=0;i<nStartPos.length;i++) 8cvSA&l(D  
fileSplitterFetch.splitterStop(); 0iC5,  
1,zc8>M  
-#;ZZ\fdj  
} L$"x*2[A  
} %&H^UxC  
//负责部分文件的抓取 )mAD<y+  
**FileSplitterFetch.java JgHYuLB  
*/ 6)=;cc{Vr  
package NetFox; 6NyUGGRq  
F5H*z\/={  
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import java.io.*; 5cM%PYU4:v  
import java.net.*; dtV*CX.D.7  
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public class FileSplitterFetch extends Thread { F@ pf._c  
#D(=[F  
|;aZi?Ek[  
String sURL; //File URL "ivVIq2  
long nStartPos; //File Snippet Start Position jp}.W  
long nEndPos; //File Snippet End Position BINHCZ  
int nThreadID; //Thread's ID =^
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boolean bDownOver = false; //Downing is over (7,Q4T  
boolean bStop = false; //Stop identical c3rj :QK6I  
FileAccessI fileAccessI = null; //File Access interface -sf[o"T,j  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException i&m6;>?`  
{ !.iFU+?V  
this.sURL = sURL; #68$'Rl"o1  
this.nStartPos = nStart; 0S+$l  
this.nEndPos = nEnd; }9B},  
nThreadID = id; l| \ -d  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Ed;!A(64r  
} zA|lbJz=GY  
=d~pr:.F  
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public void run() 3 %r*~#nz  
{ 45Zh8k  
while(nStartPos < nEndPos && !bStop) :.BjJ2[S  
{ ; %AgKgV  
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try{ UWqX}T[^  
URL url = new URL(sURL); zmuRn4Nv  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2RqV\Ji
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httpConnection.setRequestProperty("User-Agent","NetFox"); XmVst*2=  
String sProperty = "bytes="+nStartPos+"-"; `z/p,. u  
httpConnection.setRequestProperty("RANGE",sProperty); .!2 u#A  
Utility.log(sProperty); RvU'8Y?>w  
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InputStream input = httpConnection.getInputStream();  -y_q
 
//logResponseHead(httpConnection); 2.@IfBF6  
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byte[] b = new byte[1024]; (B@\Dw8^  
int nRead; )VG>6x  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) _~>WAm<  
{ }a UQ#x  
nStartPos += fileAccessI.write(b,0,nRead); 6&LmR75C  
//if(nThreadID == 1) XdlA)0S)  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); +#UawYLJ  
} >#T?]5Z'MF  
(bNoe(<qU  
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Utility.log("Thread " + nThreadID + " is over!"); 9,tk  
bDownOver = true; cuf]-C1_  
//nPos = fileAccessI.write (b,0,nRead); +uNMyVH  
} p? VDBAx  
catch(Exception e){e.printStackTrace ();} wJgH15oB  
} SuV3$-);z  
} x=\W TC  
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//打印回应的头信息 u,=?|M\  
public void logResponseHead(HttpURLConnection con) sQrM"i0Y>  
{ gCL}Ba  
for(int i=1;;i++) oj?y_0}:^  
{ |hDN$By  
String header=con.getHeaderFieldKey(i); h y\iot  
if(header!=null) #c/K.?  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); BOdlz#&s  
Utility.log(header+" : "+con.getHeaderField(header)); WkpHe  
else )#? K2E  
break; / U~yYh  
} p]s)Xys  
} ]}&HvrOld  
^H&`e"|R9  
#?>p
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public void splitterStop() cnY}^_  
{ CqX*.j{  
bStop = true; m("KLp8  
} 9*!*n ~  
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} 'w/S6j  
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/* XVKRT7U  
**FileAccess.java X VH(zJ  
*//文件访问(定位，写) FId,/la  
package NetFox; NJ$Qm
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import java.io.*; f&Sovuuh
 
#z*,-EV|  
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public class FileAccessI implements Serializable{ ']^]z".H  
@aB7dtM  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 "{bc2#F  
RandomAccessFile oSavedFile; !b$~Sm)  
long nPos; Z#kB+.U  
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public FileAccessI() throws IOException F+D e"^As  
{ e!k4Ij-]  
this("",0); YQ1rS X3  
} %r(qQM.Pl  

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public FileAccessI(String sName,long nPos) throws IOException X7?14W  
{ -2C^M> HZ  
oSavedFile = new RandomAccessFile(sName,"rw"); r"VNq&v]9  
this.nPos = nPos; gla'urb[i|  
oSavedFile.seek(nPos); iDsY5l  
} G}dq ft5"  
&pv*TL8  
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public synchronized int write(byte[] b,int nStart,int nLen) 3?+t%_[  
{ ( ~JtKSq%  
int n = -1; XE;'K`%  
try{ kH[thRk}  
oSavedFile.write(b,nStart,nLen); $P #KL//  
n = nLen; :o:/RRp[  
} O/&Qzt  
catch(IOException e) #!(2@N8  
{ I;{Ua*  
e.printStackTrace (); W6u(+P]("  
} ?. L]QU  
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return n; g/i.b&  
} ;hd%wmE  
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#=F{G4d)!=  
} 8SupoS  
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\MAv's4b@  
/* {Q^ -  
**SiteInfoBean.java 83)m#  
*/ $?OQtz@  
package NetFox; #zb67mg~  
M2qor.d  
P;IM -]  
public class SiteInfoBean { l5enlYH  
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1_@vxi~aW_  
private String sSiteURL; //Site's URL lvR>%I0`*  
private String sFilePath; //Saved File's Path rF/<}ye/4M  
private String sFileName; //Saved File's Name &mba{O  
private int nSplitter; //Count of Splited Downloading File |Fx~M,Pzg  
PaDm"+H@  
=<P$mFP2*  
public SiteInfoBean() 8xoC9!xt  
{//nSplitter的缺省值为5 K8v@)  
//default value of nSplitter is 5 7?uIl9Vk>(  
this("","","",5); +a+DiD>./  
} FlbM(ofY  
x*:"G'zT  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 
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{ R{9G$b1Due  
sSiteURL= sURL; +rDKx(Rk  
sFilePath = sPath; Ma ]*Pled  
sFileName = sName; YgQb(umK  
this.nSplitter = nSpiltter; {@tO9pc`8  
t+Qx-sW  
 qt.=  
} J(,{ -d-E  
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public String getSSiteURL() c$;Cpt@-j  
{ byk9"QeY\  
return sSiteURL; Se!B,'C%  
} 0.^67'  
aOmQ<N]a  
^W0eRT  
public void setSSiteURL(String value) XU`vs`/  
{ "OrF81  
sSiteURL = value; ?Elt;wL(  
} yM?jiy  
'pT8S  
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public String getSFilePath() V~QOl=`K:  
{ L,sXJ23.  
return sFilePath; I\=&v^]  
} 9*(uJA  
uA\KbA.c;U  
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public void setSFilePath(String value) 4CxU eq  
{ DV!0zzJ  
sFilePath = value; <t,lq  
} yONX?cS  
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public String getSFileName()
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{ io7Zv*&T0  
return sFileName; T?{F7  
} i >BQRbU  
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@-O%u*%J  
public void setSFileName(String value) r3~YGY  
{ =^w:G=ymS  
sFileName = value; z[]8"C=  
} ;Hu`BFXyD  
I5W#8g!{  
i(S}gH4*o  
public int getNSplitter() |1m2h]];Q  
{ 3Io7!:+  
return nSplitter; xp]_>WGq  
} B~u
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public void setNSplitter(int nCount) zCj#Nfm  
{ uh3<%9#\k  
nSplitter = nCount; H `_{n<  
} 5Qxm\?0J
  
} VW**N}1#C  
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/* .s3y^1C  
**Utility.java D|/ 4
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*/ (5)DQ1LaF  
package NetFox;
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xepp."
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public class Utility { -K0!wrKC  
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}J_#N.y  
public Utility() #$u7:p [t  
{ ^dKtUH/78G  
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} 2Gn26L5
 
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//线程睡眠 1j!{?t?  
public static void sleep(int nSecond) ;sY n=r  
{ 4R9y~~+  
try{ +<sv/gEt  
Thread.sleep(nSecond); Vd A!tL  
} 6FEIQ#`{  
catch(Exception e)
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{ R(GL{Dh}L  
e.printStackTrace (); +3r4GEa Z  
} +w(B9rH  
} 6f;20dn6  
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//日志 KH9D},  
public static void log(String sMsg) =L,7~9  
{ )_1;mc8B  
System.err.println(sMsg); 'A'[N :i  
} ZP"Xn/L  
qyR}|<F8*  
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public static void log(int sMsg) &>vfm9  
{ Z \;{e'#o  
System.err.println(sMsg); 1raq;^e9  
} @gjA8mL  
} e^orqw/I  
oN=>U"<\1  
bA/'IF+  
/* g ?{o2gG  
**TestMethod.java :+meaxbu  
*/ cA B<'44R  
package NetFox; QJU\YH%}  
A%.ZesjAx  
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public class TestMethod { uQz!of%x  
1F{,Zr  
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public TestMethod() c6MMI]+8  
{ ///xx/weblogic60b2_win.exe '_FxxLAO  
try{ r|Q/:UV?w  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 0uJ??4N9  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); :} DTK  
SiteFileFetch fileFetch = new SiteFileFetch(bean); l|K$6>80  
fileFetch.start(); HD>UTX`&mc  
} >yqFO  
catch(Exception e){e.printStackTrace ();} uevhW  
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\?"kT}..  
} N
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af}JS2=$  
public static void main(String[] args) E[c6*I  
{ Dh)(?"^9A  
new TestMethod(); REJHh\:.77  
} h<bCm`qj  
} j-7aJj%  
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