http断点续传简单实现（java)

/* P*>V6SK>b  
**SiteFileFetch.java W=
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*/ 9[`6f8S_$  
package NetFox; :9}*p@  
import java.io.*; |wDCIHzQ  
import java.net.*; n[@Ur2&)  

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public class SiteFileFetch extends Thread { PO&`rr  
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SiteInfoBean siteInfoBean = null; //文件信息Bean iX=*qiVX  
long[] nStartPos; //开始位置 
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long[] nEndPos; //结束位置 L6m'u6:1{  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Nu'rn*Y_  
long nFileLength; //文件长度 Q*he%@w  
boolean bFirst = true; //是否第一次取文件 y_6HQ:  
boolean bStop = false; //停止标志 wrbDbp1L  
File tmpFile; //文件下载的临时信息 rfjQx]3pB  
DataOutputStream output; //输出到文件的输出流 O%r<I*T^r  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） LdOB[W  
public SiteFileFetch(SiteInfoBean bean) throws IOException Dng^4VRd  
{ >qE$:V"_5  
siteInfoBean = bean; GOt@x9%  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); /?sV\shy  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); [#:k3aFz  
if(tmpFile.exists ()) Ev%\YI!MaY  
{ <$ 5\^y,V  
bFirst = false; tVOx  
read_nPos(); X\;y;pmRH  
} xIn
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else mWh:,[o  
{ `JRdOe  
nStartPos = new long[bean.getNSplitter()]; CVm*Q[5s"  
nEndPos = new long[bean.getNSplitter()]; R:Lu)d>=  
} 9c
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} 2,+H;Ypi!  
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<t8})
 
public void run() 2h=RNU|  
{ wNlp4Z'[  
//获得文件长度 fRiHs\+  
//分割文件 8L:0Wp  
//实例FileSplitterFetch (f)QEho7  
//启动FileSplitterFetch线程 FEkx&9]  
//等待子线程返回 s[hD9$VB>  
try{ W/ERqVZR]  
if(bFirst) R$q:Ct  
{ W+QI D/  
nFileLength = getFileSize(); DD1S]m  
if(nFileLength == -1) {0?

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{ %:NI@59  
System.err.println("File Length is not known!"); !59q@Mya[  
} ZR1EtvVG  
else if(nFileLength == -2) 6Pz\6DU,I  
{ d$!ibL#o
 
System.err.println("File is not access!"); di|l?l^l  
} K$4Ky&89  
else k20tn ew  
{ dQ<EDtap  
for(int i=0;i<nStartPos.length;i++) e.[h  
{ HxjhP(  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); +U[A.^t  
} `W5f'RU  
for(int i=0;i<nEndPos.length-1;i++) =vR>KE  
{ kp[Jl0K5  
nEndPos = nStartPos[i+1]; jN'zNOV~  
} ~!I \{(  
nEndPos[nEndPos.length-1] = nFileLength; Z',pQ{rD  
} 7>#74oy  
} d4lEd>Ni  
N)QW$iw9  
@sP?@<C  
//启动子线程 r'&VH]m  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ;X8eZQ  
for(int i=0;i<nStartPos.length;i++) #jQITS7  
{ lyP<&<Y5  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), RJ`F2b sYN  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), -0Ps.B  
nStartPos,nEndPos,i); -{HA+YL H  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 4oJ0,u  
fileSplitterFetch.start(); tlj^0  
} ,a}+Jj{  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), uKK+V6}!kj  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); *t63c.S  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", LVX.stN#p  
nEndPos = " + nFileLength); .RdnJ&K*  
// fileSplitterFetch[nPos.length-1].start(); z&w@67 >j  
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_  
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//等待子线程结束 "
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//int count = 0; m}rUc29cS,  
//是否结束while循环 U2;_{n*g%  
boolean breakWhile = false; &4L
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while(!bStop) 3{CXIS  
{ p~qdkA<  
write_nPos(); MFRM M%`  
Utility.sleep(500); }}<^fM  
breakWhile = true; s$A|>TOY  
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for(int i=0;i<nStartPos.length;i++) QN":Qk(,q  
{ dW6sA65<Y  
if(!fileSplitterFetch.bDownOver) A2..gs/  
{ I=0`xF|4K-  
breakWhile = false; T< D&%)  
break; ta%yQd
7  
} u{J$]%C   
} F8nR.|  
if(breakWhile) *y0TtEd;  
break; 05Ak[OOU>  
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B
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//count++; eot%Th?[  
//if(count>4) vkp_v1F%+  
// siteStop();  _->d41  
} EJrP{GH  
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System.err.println("文件下载结束！"); =A{F&:+a]  
} @kd`9Yw  
catch(Exception e){e.printStackTrace ();} ^?}-x  
} -V7dSi  
/V0[Urc@  
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//获得文件长度 6o
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public long getFileSize() n86LU Sj5  
{ !cW6dc^  
int nFileLength = -1; .kcyw>T`I  
try{ LtW}R4}3  
URL url = new URL(siteInfoBean.getSSiteURL()); ~wvu7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); k..AP<hH  
httpConnection.setRequestProperty("User-Agent","NetFox"); f3^Anaa]l  
*PM#ngLX}r  
}]<0!q &xB  
int responseCode=httpConnection.getResponseCode(); DHQS7%)f`  
if(responseCode>=400) xa8;"Y~"bg  
{ VYbH:4K@%  
processErrorCode(responseCode); ^,}1^?*  
return -2; //-2 represent access is error zcGmru|k  
} TophV}@B`  
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String sHeader; 8 kvF~d ;  
cDS\=Bf  
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for(int i=1;;i++) /*P) C'_M  
{ 2ci[L:U  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); z.lIlp2:  
//Utility.log(in.readLine()); =U'!<w<-  
sHeader=httpConnection.getHeaderFieldKey(i); > 9.%hSy  
if(sHeader!=null) AO, o|,#4F  
{ S#kYPe  
if(sHeader.equals("Content-Length")) s@zO`uBc  
{ (1 (~r"4I  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 7>"dc+Fg  
break; L+N\B@ 0-  
} # ~Doz7~  
} ?zex]!R  
else >$,P )cB'  
break; .dI".L  
} #lR-?Uh  
} $Q"D>Qf{G  
catch(IOException e){e.printStackTrace ();} 'Fy"|M;2  
catch(Exception e){e.printStackTrace ();} (\ge7sE-oo  
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Utility.log(nFileLength); /%g+|C  
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return nFileLength; rGQ2 ve  
} Bv<aB(c  
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.' }jd#  
//保存下载信息（文件指针位置） O uNPDq%  
private void write_nPos() ?r0rY?  
{ `WIZY33V  
try{ , #=TputM  
output = new DataOutputStream(new FileOutputStream(tmpFile)); s_ t/  
output.writeInt(nStartPos.length); C~egF=w  
for(int i=0;i<nStartPos.length;i++) ? X6M8`  
{ r0!')?#Z  
// output.writeLong(nPos); f0vO(@I  
output.writeLong(fileSplitterFetch.nStartPos); #9gx4U  
output.writeLong(fileSplitterFetch.nEndPos); KLvAe
>#,  
} p[w! SR%=  
output.close(); LN~mKoW  
} ]DKRug5  
catch(IOException e){e.printStackTrace ();} Q 9fK)j1$  
catch(Exception e){e.printStackTrace ();} EB| iW2'  
} dP?prT  
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//读取保存的下载信息（文件指针位置） 3_<l`6^Ns/  
private void read_nPos() ").gPmC  
{ $33E-^  
try{ $TfB72  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); (?m{G Q  
int nCount = input.readInt(); 2TUV9Z  
nStartPos = new long[nCount]; & XmaGtt  
nEndPos = new long[nCount];
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for(int i=0;i<nStartPos.length;i++) [I=|"Ic~  
{ rCwE$5 b  
nStartPos = input.readLong(); [3"F$?e5  
nEndPos = input.readLong(); vn+XY=Qnr  
} gUNhN1=  
input.close(); G&xtL  
} Pr1qX5>=  
catch(IOException e){e.printStackTrace ();} y{/7z}d  
catch(Exception e){e.printStackTrace ();} 0KnL{Cj   
} M^[;{p2uZ  
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private void processErrorCode(int nErrorCode) hH 5}%/vF  
{ TKM^  
System.err.println("Error Code : " + nErrorCode); 4^uSW&`;/  
} E{EO9EI  
KJRAW]?{  
& ?xR  
//停止文件下载 Gsv<Rjj:  
public void siteStop() lhHH|~t0  
{ M#; ks9  
bStop = true; @Wc5r#  
for(int i=0;i<nStartPos.length;i++) .6P.r}  
fileSplitterFetch.splitterStop(); YZ5,K6u  
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} g35!a<JW  
} Vf;&z$D{r  
//负责部分文件的抓取 ka~_iUU4  
**FileSplitterFetch.java 0K[]UU=P=  
*/ BbI%tmA7  
package NetFox; b%0p<*:a/  
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import java.io.*; h{gFqkDoTI  
import java.net.*; \rF
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public class FileSplitterFetch extends Thread { uR ?W|a  
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String sURL; //File URL W}f)VC;D  
long nStartPos; //File Snippet Start Position nd]SI;<  
long nEndPos; //File Snippet End Position (da`aRVDp  
int nThreadID; //Thread's ID =SXdO)%2  
boolean bDownOver = false; //Downing is over F%h3?"s  
boolean bStop = false; //Stop identical 8@;]@c)m  
FileAccessI fileAccessI = null; //File Access interface zMR)w77  
q2*A'C  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException !HvA5'|:}  
{ iX$G($[l(  
this.sURL = sURL; hI'WfF!X  
this.nStartPos = nStart; g}NO$?ndg  
this.nEndPos = nEnd;
pcy;]U?  
nThreadID = id; <{isWEW9]3  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 jc&k-d>=G  
} !&{rnK  
{4D`VfX_  
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public void run() =#2c r:1  
{ ;cXw;$&D  
while(nStartPos < nEndPos && !bStop) Bn7uKa{P  
{ J?9jD:x  
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try{ LqbI/AQ)  
URL url = new URL(sURL); vkIIuNdDlx  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); &"^F;z/  
httpConnection.setRequestProperty("User-Agent","NetFox"); Ca|egQv  
String sProperty = "bytes="+nStartPos+"-"; E+aePoU  
httpConnection.setRequestProperty("RANGE",sProperty); S"cTi[9  
Utility.log(sProperty); m\56BP-AM  
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InputStream input = httpConnection.getInputStream(); e$J>z {  
//logResponseHead(httpConnection); C^L+R7  
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byte[] b = new byte[1024]; wtw=RA  
int nRead; w"v!+~/9  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) r{;NGQYs  
{ g&s. 0+  
nStartPos += fileAccessI.write(b,0,nRead); N1$u@P{  
//if(nThreadID == 1) ,^:{!?v  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); n93q8U6m/U  
} ?{ N,&d  
IrMHAM5K  
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Utility.log("Thread " + nThreadID + " is over!"); )0VL$A  
bDownOver = true; 'z ?Hv  
//nPos = fileAccessI.write (b,0,nRead); x4WCAqi/2  
} cUY-  
catch(Exception e){e.printStackTrace ();} iFd !ED  
} {
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} 'z$$ZEz!C  
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//打印回应的头信息 Zw]"p63eMa  
public void logResponseHead(HttpURLConnection con) l7|z]v-  
{ O] @E8<?^  
for(int i=1;;i++) lq-KM
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{ &t=:xVn-M  
String header=con.getHeaderFieldKey(i); \ %Mcvb.?  
if(header!=null) 8!E.3'jb  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); IRN,=  
Utility.log(header+" : "+con.getHeaderField(header)); W/qXQORv  
else L7$f01*  
break; g-eJan&]N  
} 5W&L6.J}+  
} 2][9Wp  
?2]fE[SqY  
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public void splitterStop() f/)Y {kS6  
{ ui%#f1Iq
 
bStop = true; 0V:H/qu8>  
} =\<NTu  
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} e$[O J<t  
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/* +F)EGB%LXs  
**FileAccess.java
GW AT0  
*//文件访问(定位，写) Ui'v' $  
package NetFox; t]h_w7!U  
import java.io.*; 2R\K!e  
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public class FileAccessI implements Serializable{ |{#St-!-7  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 L]=]/>jQ6  
RandomAccessFile oSavedFile; YK/? mj1x  
long nPos; Qc7*p]E&  
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public FileAccessI() throws IOException $MR1 *_\V  
{ pr<u 5  
this("",0); Cj=R\@  
} <f>77vh0  
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public FileAccessI(String sName,long nPos) throws IOException j,OA>{-$  
{ %r^tZ;;l  
oSavedFile = new RandomAccessFile(sName,"rw"); .#&)%}GC  
this.nPos = nPos; tj;47UtH  
oSavedFile.seek(nPos); y4kn2Mw;  
} 7J);{ &x9h  
OeQ[-e  
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public synchronized int write(byte[] b,int nStart,int nLen) k6#$Nb606  
{ e|tx`yA  
int n = -1; 7m#EqF$P  
try{ E-WpsNJ)X  
oSavedFile.write(b,nStart,nLen); lf=G  
n = nLen; EB3/o7)L  
} P
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catch(IOException e) jRsl/dmy  
{ Tb]7# v  
e.printStackTrace (); p*<Jg l  
} /we]i1-9  
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return n; }1 O"?6  
} ]WMzWt:L  
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} N:B<5l '  
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/* x_3B) &9  
**SiteInfoBean.java ?b7ttlX{  
*/ >,,`7%Rv  
package NetFox; y{M7kYWtHV  
MsIR~  
>~ *wPoW  
public class SiteInfoBean { ^P,Pj z  
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private String sSiteURL; //Site's URL iY>P7Uvvz  
private String sFilePath; //Saved File's Path 3[Q7'\  
private String sFileName; //Saved File's Name (g@X.*c8  
private int nSplitter; //Count of Splited Downloading File <zpxodM@T  
+tk`$g  
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public SiteInfoBean() 8pEA3py  
{//nSplitter的缺省值为5 C[fefV9g2  
//default value of nSplitter is 5 Z'A 3\f   
this("","","",5); ^zTe9:hz/\  
} bj`GGxzOb  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ZklO9Ox(  
{ >&\.{ aj  
sSiteURL= sURL; .<vXj QE  
sFilePath = sPath; g}R#0gkdk}  
sFileName = sName; P$z%:Q  
this.nSplitter = nSpiltter; @_t=0Rc  
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y  
} +wz1kPRs  
R<fF ^^  
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public String getSSiteURL() eaO'|@;{~  
{ ]O}e{Q>  
return sSiteURL; Ae=JG8Ht~  
} <V)z{uK  
=p5]r:9W  
3{.]!  
public void setSSiteURL(String value) 02J(*_o  
{ u[KxI9Q  
sSiteURL = value; "c} en[  
} =}tomN(F~[  
=c 9nC;C  
>o13?-S%e  
public String getSFilePath() > dVhIbG  
{ T}z? i  
return sFilePath; g?|Z/eVJ  
} cQxUEY('+  
$,O8SW.O$  
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public void setSFilePath(String value)  z9&j  
{ 2.</n}g  
sFilePath = value; _t"[p_llo  
} D1+1j:m  

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public String getSFileName() wbOYtN Y@  
{ oCE'@}s.i  
return sFileName; CAviP61T  
} doTbol?+  
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A@_>9;   
public void setSFileName(String value) R}w}G6"\  
{ Gjq7@F'  
sFileName = value; ` ;mQ"lO  
} K_ymA,&()  
)TVd4s(e  
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public int getNSplitter() #"c'eG0  
{ j7:r8? G  
return nSplitter; ks phO-  
} N;YF
r  
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public void setNSplitter(int nCount) xv2c8g~vD  
{ @,=pG  
nSplitter = nCount; ,J+L_S+B~  
} 9XQE5^  
} &qPezyt  
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/* 
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**Utility.java mzM95yQ^Z  
*/ ZZ
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package NetFox; T#!% Uzz  
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public class Utility { {E(2.'d  
#r"|%nOfY  
( sl{Rgxe*  
public Utility() zOMxg00  
{ -,;woOG  
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} f4AN"rW  
~vpF|4Zn5  
//线程睡眠 5tkKd4VfL
 
public static void sleep(int nSecond) PN9vg
9'  
{ l,Y5VGiH#  
try{ s&o9LdL  
Thread.sleep(nSecond); I:oEt  
} h*JN0O<b  
catch(Exception e) W3Ee3  
{ S9$,.aq  
e.printStackTrace (); am3JzH  
} #E=8kbD7  
} V D7^wd9  
4?@#w>(  
//日志 |[5;dt_U/  
public static void log(String sMsg) 2 KH
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{ oI`Mn3N  
System.err.println(sMsg); xjnAK!sD  
} s}Go")p<:  
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public static void log(int sMsg) 3}phg  
{ MIkp4A  
System.err.println(sMsg); .eVX/6,  
} gn/]1NN
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} O^./)#!#  
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/* DC> R  
**TestMethod.java G8w@C
 
*/ &I)tI^P}  
package NetFox; Nlm}'Xt  
[];wP'*  
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public class TestMethod { 6A5.n?B{  
la)+"uW  
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public TestMethod() 0Qeda@J  
{ ///xx/weblogic60b2_win.exe $
1d{R;b[  
try{ tAep_GR  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7z,  $  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); OA9P"*  
SiteFileFetch fileFetch = new SiteFileFetch(bean); gU&+^e >  
fileFetch.start(); 2<n18-|OQ  
} OPq|4xu  
catch(Exception e){e.printStackTrace ();} ,-EN{ed  
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} AIQ {^:  
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public static void main(String[] args) ":/Vp
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{ `g(#~0R  
new TestMethod(); ?RG;q  
} nSSJl  
} jZidT9[g  
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