http断点续传简单实现（java)

/* ^g^R[8  
**SiteFileFetch.java {, +,:w7  
*/ J/OG\}  
package NetFox; <]{$XcNm  
import java.io.*; K=S-p3\g  
import java.net.*; J3 Y-d7=|  
k :KN32%  
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public class SiteFileFetch extends Thread { /=o~7y  
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SiteInfoBean siteInfoBean = null; //文件信息Bean H>
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long[] nStartPos; //开始位置 W8bh49  
long[] nEndPos; //结束位置 Vr%>'XN>"  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 hDPZj#(c  
long nFileLength; //文件长度 F6g)2&
e{/  
boolean bFirst = true; //是否第一次取文件 8\
V  
boolean bStop = false; //停止标志 by*?PhfF  
File tmpFile; //文件下载的临时信息 V?_:-!NJ(  
DataOutputStream output; //输出到文件的输出流 QkY]z~P4  
:9nqQJ+~  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） i-kj6N5  
public SiteFileFetch(SiteInfoBean bean) throws IOException q oA?  
{ _f^JXd,7v  
siteInfoBean = bean; No
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); |DB7o+4  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ">-J+ST%  
if(tmpFile.exists ()) */8b)I}yY  
{ YB;q5[  
bFirst = false; ?o0ro?9j  
read_nPos(); 3u&>r-V6Fn  
} *?l-:bc]  
else 397IbZ\  
{ l*l?aI  
nStartPos = new long[bean.getNSplitter()]; >VnBWa<j3  
nEndPos = new long[bean.getNSplitter()]; ]x;*Z&  
} =I(F(AE  
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} \my5E\  
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public void run() 
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{ VXfp=JE  
//获得文件长度 sN"JVJXi  
//分割文件 Ah_,5Z@&R  
//实例FileSplitterFetch seNJ6p=`  
//启动FileSplitterFetch线程 +1uAzm4SL  
//等待子线程返回 }KEL{VUX  
try{ 2cnyq$4k  
if(bFirst) `<cnb!]  
{ [wLK*9@&  
nFileLength = getFileSize(); KR49Y>s<  
if(nFileLength == -1) d9qA\ [  
{ cPx]:sC  
System.err.println("File Length is not known!"); s|cL mL[  
} 84X/=l-c=  
else if(nFileLength == -2) By&ibN),  
{ v@qU<\Y>  
System.err.println("File is not access!"); J>o%6D  
} :"ta#g'  
else %I`%N2ss  
{ ?QbxC,& i  
for(int i=0;i<nStartPos.length;i++) AlVBhR`  
{ GC#s;X  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); #8{U0 7]"  
} OrG1Mfx&2%  
for(int i=0;i<nEndPos.length-1;i++) w$`[C+L  
{ ],?$&  
nEndPos = nStartPos[i+1]; @7}
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} [?QU'[  
nEndPos[nEndPos.length-1] = nFileLength; b235Zm  
} REK(^1 h  
} hxT{!g  
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//启动子线程 {S$]I)tV  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; mdNIC  
for(int i=0;i<nStartPos.length;i++) CogN1,GJ  
{ +N3f{-{"Yo  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Dr_ (u<[  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), zJMm=Mw^  
nStartPos,nEndPos,i); >QA;02  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); =sIkA)"!=  
fileSplitterFetch.start(); -wdd'G  
} X5Fi , /H  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Y|3n^%I  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); uOv0ut\\G  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", >Q-"-X1  
nEndPos = " + nFileLength);  l,lfkm  
// fileSplitterFetch[nPos.length-1].start(); rBLcj;,
 
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CAJ]@P#Xj+  
//等待子线程结束 Y3n6y+Uzk  
//int count = 0; A,u}p rwH  
//是否结束while循环 H,Y+n)5  
boolean breakWhile = false; 'v~%rhq3  
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while(!bStop) pWm==Ds|  
{ Wcf;ZX
  
write_nPos(); NB.
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Utility.sleep(500); |Nf90.dL  
breakWhile = true; ?TLzOYJp  
lx H3a :gm  
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for(int i=0;i<nStartPos.length;i++) ->u}b?aF  
{ cH7Gb|,M  
if(!fileSplitterFetch.bDownOver) YqEB%Y~N+  
{ R2Y.s^  
breakWhile = false; -~rZ| W~v  
break; vMHJgpd&j  
} sI OT6L^7  
} X$0&tmum  
if(breakWhile) D=^|6}  
break; i^Ip+J+[  
P2t9RCH  
)J>-;EYb8  
//count++; "BvAiT
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//if(count>4) 3[UB3F4K  
// siteStop(); i2yE-sgF  
} 7lH.>
n  
`JZ`j7f  
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System.err.println("文件下载结束！"); g~v>{F+u  
} ,?KN;~t#vz  
catch(Exception e){e.printStackTrace ();} +>BD^[^^  
} 6qF9+r&e?  
'<!T'l:R:/  
<?E~Qc t  
//获得文件长度 Oe_*(q&  
public long getFileSize() R\MFh!6sn  
{ ~6!TMVr  
int nFileLength = -1; _Z0O]>KH  
try{ #[ TOe  
URL url = new URL(siteInfoBean.getSSiteURL()); )r`F}_CEL  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 8w\ZY>d  
httpConnection.setRequestProperty("User-Agent","NetFox"); *f*o ,~8V1  
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int responseCode=httpConnection.getResponseCode(); $
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if(responseCode>=400) D"vl$BX  
{ =K8z8K?  
processErrorCode(responseCode); t \;,$i  
return -2; //-2 represent access is error {~0r3N4Zl  
} }M|,Z'@*  
.?NraydwV  
[6}>
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String sHeader; F&6Xo]?  
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for(int i=1;;i++) CGCI3Z'  
{ L^%jR=  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); NU/:jr.W#  
//Utility.log(in.readLine()); ZGgM-O1  
sHeader=httpConnection.getHeaderFieldKey(i); L; (J6p]h  
if(sHeader!=null) uk<JV*R=  
{ _I<LB0kgf.  
if(sHeader.equals("Content-Length")) `F,*NESv  
{ Jr.4Y>;}e3  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); (;T g1$  
break; o"Mhwh  
} }\oy%]_mY  
} UtzM+7r@  
else 2(s-8E:  
break; ;Svs|]d  
} }Q#3\z
5  
} n/vKxtW  
catch(IOException e){e.printStackTrace ();} FJH'!P\  
catch(Exception e){e.printStackTrace ();} !W48sZr1&  
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Utility.log(nFileLength); i8+[-mh  
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return nFileLength; 7 yp}  
} Q3P*&6wA  
>u/ T`$  
;RW024  
//保存下载信息（文件指针位置） >og- jz  
private void write_nPos() `44 }kkBT  
{ -j"]1JLQ  
try{ |x$2-RUP  
output = new DataOutputStream(new FileOutputStream(tmpFile)); j" ~gEGfK  
output.writeInt(nStartPos.length); I
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for(int i=0;i<nStartPos.length;i++) wzNGL{3  
{ IWs)n1D*]  
// output.writeLong(nPos); ;Q8LA",5d  
output.writeLong(fileSplitterFetch.nStartPos); e>~7RN  
output.writeLong(fileSplitterFetch.nEndPos); Puodsd  
} @p$$BUb  
output.close(); uYy&<_r  
} nAY'1!Oi  
catch(IOException e){e.printStackTrace ();} O$,bNu/g  
catch(Exception e){e.printStackTrace ();} rJws#^]  
} (sN;B)  
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//读取保存的下载信息（文件指针位置） 0.kQqy~5  
private void read_nPos() i
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{ FAbl
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try{ :W*']8 M-  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); R0DWjN$j  
int nCount = input.readInt(); Di>
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nStartPos = new long[nCount]; CTh!|mG  
nEndPos = new long[nCount]; EN/e`S$)  
for(int i=0;i<nStartPos.length;i++) J0V\_ja-  
{ XPd@>2  
nStartPos = input.readLong(); WB(Gx_o3  
nEndPos = input.readLong(); \
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} w$j!89@)  
input.close(); pj/w9j G6  
} ML-?#jNa<  
catch(IOException e){e.printStackTrace ();} oJ`cefcWo  
catch(Exception e){e.printStackTrace ();} ]^c]*O[8  
} 'pQ\BH  
\ N;%
 
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private void processErrorCode(int nErrorCode) #!RO,{FT  
{ N}5'Hk4
+  
System.err.println("Error Code : " + nErrorCode); VyWPg7}e  
} ^Z`?mNq9  
lVR a{._m  
Kh,zp{  
//停止文件下载 l.@&B@5F  
public void siteStop() -er8(snDQ  
{ w</qUOx  
bStop = true; ,p7W4;?4  
for(int i=0;i<nStartPos.length;i++) 4y|%Oj  
fileSplitterFetch.splitterStop(); w$%1j+%&
 
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} M,(UCyT  
} V<W$h`  
//负责部分文件的抓取 _DAj$$ Ru4  
**FileSplitterFetch.java -FrNk>  
*/ 3,[#%}1(S  
package NetFox; KV {J>J1  
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import java.io.*; =&YhA}l\O  
import java.net.*; ]UFbG40Zo  
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public class FileSplitterFetch extends Thread { 6-!U\R2Z>  

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String sURL; //File URL w4%yCp[,  
long nStartPos; //File Snippet Start Position y)]L>o~  
long nEndPos; //File Snippet End Position 7v{s?h->$  
int nThreadID; //Thread's ID JK_(!  
boolean bDownOver = false; //Downing is over uE%$<o*#  
boolean bStop = false; //Stop identical @kmOz(  
FileAccessI fileAccessI = null; //File Access interface KCc7u8   

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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Yp(F}<f?  
{ d@aPhzLu  
this.sURL = sURL; .|Y&,?k|Y  
this.nStartPos = nStart; @?E|]H!S]  
this.nEndPos = nEnd; lS!uL9t.  
nThreadID = id; T**v!Ls  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 4Ow0g-{  
} K|^'`FpPO  
/@qnEP%  
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public void run() U,e'vS{  
{ _dk/SWb)  
while(nStartPos < nEndPos && !bStop) $7 FT0?kG  
{ G>>TB{}  
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try{ ZA{T0:  
URL url = new URL(sURL); h =E)5&Z  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); B;=-h(E}vJ  
httpConnection.setRequestProperty("User-Agent","NetFox"); zC<k4[.  
String sProperty = "bytes="+nStartPos+"-"; Lw_s'QNWR  
httpConnection.setRequestProperty("RANGE",sProperty); !gbPxfH:6  
Utility.log(sProperty); & Y Y^Bd#  
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InputStream input = httpConnection.getInputStream(); >.4mAO  
//logResponseHead(httpConnection); |'ML )`c[  
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byte[] b = new byte[1024]; @eOD+h'  
int nRead; HJ^SqSm  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) yNU.<d 5  
{ 1 |T{RY5  
nStartPos += fileAccessI.write(b,0,nRead); jPc"qER!  
//if(nThreadID == 1) {Z!x]}{M  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); IVdM}"+  
} 9hn+eU  
, tb\^  
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Utility.log("Thread " + nThreadID + " is over!"); "`q:
  
bDownOver = true; g+1&liV  
//nPos = fileAccessI.write (b,0,nRead); ~>-MVp  
} *JT,]7>  
catch(Exception e){e.printStackTrace ();} Y5,[udF:O  
} ":!7R<t  
} NcMohpkq  
vj,OX~|  
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//打印回应的头信息 /|MHZ$Y9w?  
public void logResponseHead(HttpURLConnection con) LfsqtQ=J`  
{ mtd ,m  
for(int i=1;;i++) pEp`Z,p  
{ IMcuoQ5  
String header=con.getHeaderFieldKey(i); R&MdwTa  
if(header!=null) VxA?LS`  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); rK@XC +`S  
Utility.log(header+" : "+con.getHeaderField(header)); Vz @2_k   
else vmsrypm  
break; %pG^8Q()   
} [~&yLccN  
} ~OSgpM#O!T  
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public void splitterStop() hI>vz"J  
{ DElrY)3O.  
bStop = true; Q/zlU@  
} ;eY.4/*R  
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} 0*^>/*  
d
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/* -g\;B  
**FileAccess.java s{9G//  
*//文件访问(定位，写) ` G-V %  
package NetFox; >h3m/aeNC  
import java.io.*; ZULnS*V;5  
iO@UzD#v  
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public class FileAccessI implements Serializable{ Cno+rmsfT  
1Wr,E#+C  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Nbvs_>N  
RandomAccessFile oSavedFile; |w].*c}Z  
long nPos; HE|XDcYO  
KBOp}MEz  
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public FileAccessI() throws IOException N(Sc!rX  
{ +oevNM  
this("",0); \`U=pZJ  
} XT%\Ce!  
r\T'_wo  
/nWBol,  
public FileAccessI(String sName,long nPos) throws IOException riv8qg  
{ E*AI}:or;  
oSavedFile = new RandomAccessFile(sName,"rw"); @s.civ!Yk  
this.nPos = nPos; sXaudT  
oSavedFile.seek(nPos); N3(.7mxo  
} ORx6r=zg  
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nghpWODq  
public synchronized int write(byte[] b,int nStart,int nLen) v2l*n  
{ cw3j&k  
int n = -1; W7#dc89}  
try{ 8vqx}2  
oSavedFile.write(b,nStart,nLen); zQ~ax!}R  
n = nLen; 8AQ__&nT  
} H@!]5 <:9  
catch(IOException e) b[KZJLZ)  
{ ,n3e8qd  
e.printStackTrace (); _J"fgxW  
} aY
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P
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return n; y|/[;  
} 1I?`3N  
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} i_e%HG  
yu>)[|-  
oJ?,X^~_  
/* < Dt/JA(p  
**SiteInfoBean.java BUS4 T#D  
*/ VVJIJ9L&C  
package NetFox; 9? y&/D5O  
*3\*GatJ  
4;*
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public class SiteInfoBean { H
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N 9W,p2  
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private String sSiteURL; //Site's URL _9C,N2a{C  
private String sFilePath; //Saved File's Path B~B,L*kC2  
private String sFileName; //Saved File's Name (YM2Cv{4  
private int nSplitter; //Count of Splited Downloading File 6Ts[NXa  
}jg1..)"<  
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public SiteInfoBean() OcLahz6  
{//nSplitter的缺省值为5 )G),iy  
//default value of nSplitter is 5 F0kdwN4;  
this("","","",5); k+BY3a  
} ]P/i}R:  
:s*t\09V7  
K7R!E,oPg  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 2m^qXE$  
{ I0*N "07n  
sSiteURL= sURL; X-*LA*xbN  
sFilePath = sPath; fjCFJ_  
sFileName = sName; d$^@$E2f  
this.nSplitter = nSpiltter; *ze,
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3rBID  
} qP0UcG  
22'Ra[  
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public String getSSiteURL() {53|X=D64  
{ `S+n,,l  
return sSiteURL; iJH?Z,Tjf  
} g/frg(KF  
;nrkC\SYh:  
EW`3$J;  
public void setSSiteURL(String value) } m"':f  
{ .k$Yleg  
sSiteURL = value; xR8y"CpE  
} ~ mzX1[  
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uFA}w:Fm  
public String getSFilePath() >0_{80bdO  
{ Oyb0t|do+  
return sFilePath; +|Izjx]
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} `A9fanh  
*{,}pK2*  
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public void setSFilePath(String value) 7 0PGbAD  
{ m>|7&l_  
sFilePath = value; k[)/,1  
} d3\KUR^  
BiDyr  
|ZC'a!  
public String getSFileName() O`$\Plt|v  
{ +koW3>  
return sFileName; Lr9E02  
} k<x7\T  
1BgHkDW  
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public void setSFileName(String value) B2Rpd &[  
{ fw VI%0C@  
sFileName = value; "!_vQ^y  
} gF`hlYD  
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~^'WHuzPy  
public int getNSplitter() ?gBFfi  
{ ^q`RaX)  
return nSplitter; /;vHAtt;f  
} !Na@T]J  
6v74mIRn'?  
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public void setNSplitter(int nCount) v}id/brl  
{ u1gD*4+  
nSplitter = nCount; Nf)SR#;  
} =dwy 4  
} "&{.g1i9  
6J_
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ZuZCIqN  
/* D^a(|L3;  
**Utility.java :wEy""*N0  
*/ q&}+O  
package NetFox; i9V,  
c$lZ\r"  
mN>(n+ly  
public class Utility { Yg}b%u,Q  
o^'QGs"  
;.<HpDfG_  
public Utility() ZmycK:f  
{ Jz*A!Li  
cj^hwtx   
u{w,y.l1h  
} 0x<
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Q5l+-  
//线程睡眠 Lxv6\3I+  
public static void sleep(int nSecond) {;m|\652B  
{ of GoaH*h  
try{ 52
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Thread.sleep(nSecond); =GW[UnO  
} m=Gb<)Y  
catch(Exception e) ;Wa&Dg/5`  
{ Jl6lZd(Np  
e.printStackTrace (); dt>9mF q  
} ^w&!}f+  
} X4!Jj*  
` @
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//日志 fW[RCd
 
public static void log(String sMsg) o\PHs4Ws'7  
{ o q6^  
System.err.println(sMsg); 4)>S3Yr  
} KV-h~C  
;.rY`<|  
JS
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public static void log(int sMsg) ^.  
{ CJDNS21m  
System.err.println(sMsg); mB6%. "  
} GctV  
} Kr<UPr  
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+WKN
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/*
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**TestMethod.java y&eU\>M  
*/ UR S=1+  
package NetFox; w~jm0jK]  
|/$954Hr#<  
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public class TestMethod { A0,e3gb  
_ b</ ::Tp  
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public TestMethod() 8J
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{ ///xx/weblogic60b2_win.exe Z6Z/Y()4Tl  
try{ xP
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); CN}0( 2n  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); P_H_\KsH*(  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Y*O Bky  
fileFetch.start(); g:!R't?  
} e\f\CMb  
catch(Exception e){e.printStackTrace ();} &Vu-*?  
(d*||"  
QC&,C}t,  
} !4<A|$mQ  
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*UXa.kT@  
public static void main(String[] args) \PFjw9s  
{ ,H<nNBv3M  
new TestMethod(); 9 g- 8u+&  
} 1'iQlnMO@  
} g6S-vSX,  
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