http断点续传简单实现（java)

/* *0a7H$iQ(]  
**SiteFileFetch.java :^QV,d<C  
*/
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package NetFox; .b*-GWx  
import java.io.*; hA~5,K0b  
import java.net.*; @M }`nKXM  
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public class SiteFileFetch extends Thread { T5-'|+  
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#zd}xla0]  
SiteInfoBean siteInfoBean = null; //文件信息Bean q=BAYZ\`  
long[] nStartPos; //开始位置 Zq}Cl'f  
long[] nEndPos; //结束位置 t&bE/i_T  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 | qf8y  
long nFileLength; //文件长度 !.{{QwZ  
boolean bFirst = true; //是否第一次取文件 ybm&g( -\  
boolean bStop = false; //停止标志 ~]K<Vh`  
File tmpFile; //文件下载的临时信息 A
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DataOutputStream output; //输出到文件的输出流 v".u#G'u  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） l>>,~  
public SiteFileFetch(SiteInfoBean bean) throws IOException z1~U#  
{ ;%i.@@:IQ  
siteInfoBean = bean; $0E_4#kwB  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 1Yv#4t  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 7\;gd4Ua1  
if(tmpFile.exists ()) laFF/g;sRC  
{ F a'2i<  
bFirst = false; ;6zp,t0  
read_nPos(); .l&<-l;UQ  
} $3n@2 N`  
else &5wM`  
{ QVrMrm+vRv  
nStartPos = new long[bean.getNSplitter()]; nR~L$Wu5_a  
nEndPos = new long[bean.getNSplitter()];
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} s*pgR=dZZ  
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} KEj-y+  
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public void run() .@ElfPP(L  
{
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//获得文件长度 !M&B=vk4  
//分割文件 Q:B
:  
//实例FileSplitterFetch pb5'5X+  
//启动FileSplitterFetch线程 f)+fdc  
//等待子线程返回 fOyLBixR  
try{ aTy&"  
if(bFirst) .sDVBT'%  
{ 9m fYB  
nFileLength = getFileSize(); u{ .UZTn  
if(nFileLength == -1) Qy@r&  
{ Q4MTedj1H  
System.err.println("File Length is not known!"); S|%f<zAtJ  
} [sY>ac  
else if(nFileLength == -2) A%s"WSx,  
{ $fY4amX6Z  
System.err.println("File is not access!"); 8Mq] V v  
} G =+sW  
else z<jWy$Ta;  
{ l~M86 h  
for(int i=0;i<nStartPos.length;i++) {^bs }($J  
{ aT1T.3 a  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 7pMQ1-(  
} ^-?5=\`5  
for(int i=0;i<nEndPos.length-1;i++) 7^7Rk  
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nEndPos = nStartPos[i+1]; /fC@T  
} @RGVcfCG)  
nEndPos[nEndPos.length-1] = nFileLength; eIBHAdU+g/  
} VU3xP2c:  
} ):OGhW
q  
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}`#OA]NZ  
//启动子线程 ivg:`$a[  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; N=FU>qbz  
for(int i=0;i<nStartPos.length;i++) $Y.Z>I;  
{ 2g5Ft  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), M\O6~UFq!  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), SFCKD/8  
nStartPos,nEndPos,i); ],CJSA!5F  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1T:M?N8J  
fileSplitterFetch.start(); RzCC>-  
} fq(r,h=|  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), H }w"4s  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); $MD|YW5  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 1-[~}  
nEndPos = " + nFileLength); ?&$??r^i  
// fileSplitterFetch[nPos.length-1].start(); H%
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L".Qf|b*  
,FRFH8p  
//等待子线程结束 PhBdm'  
//int count = 0; *#+e_)d  
//是否结束while循环 (qd$wv^h  
boolean breakWhile = false; ?w'a^+H  
BzBij^h  

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while(!bStop) 1,@-y#V_  
{ *V+6409m  
write_nPos(); HDqPqrWm  
Utility.sleep(500); Q79& Q04XN  
breakWhile = true; Zwy8SD'L  
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for(int i=0;i<nStartPos.length;i++) _~!*|<A_  
{ 3`sM/BoA  
if(!fileSplitterFetch.bDownOver) BDoL)}bRE  
{ Z#7T!/28  
breakWhile = false; &atT7m  
break; =f'MiU!p6  
} me]O  
} 7^$PauAv  
if(breakWhile) U 7mA~t2E  
break; MgJiJ0y  
|jB]5ciT  
0CXh|AU  
//count++; 9_Tk8L#  
//if(count>4) VsS.\1  
// siteStop(); Cb}hE ro  
} g7*cwu  
v_Om3i9$E  
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System.err.println("文件下载结束！"); _nw=^zS  
} i8R.Wl$l  
catch(Exception e){e.printStackTrace ();} x`N_tWZ  
} =hE5 ?}EP+  
=Ny&`X#F  
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//获得文件长度 yQ\K;  
public long getFileSize() ?^iX%   
{ zt/p'khP3  
int nFileLength = -1; z_fR?~$N2  
try{ :`BZ,j_  
URL url = new URL(siteInfoBean.getSSiteURL()); i<<NKv8;  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); &.k'Dj2hf  
httpConnection.setRequestProperty("User-Agent","NetFox"); d;(&_;  
*O') {(  
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int responseCode=httpConnection.getResponseCode(); hDc,#~!  
if(responseCode>=400) v5"5UPi-  
{ 3md yY\+&  
processErrorCode(responseCode); [\N,ow,n  
return -2; //-2 represent access is error @}@`lv65}  
} #;. tVo I  
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String sHeader; [uO
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for(int i=1;;i++) S!gV\gEbDj  
{ e*gCc7zz  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); `X?l`H;#  
//Utility.log(in.readLine()); S3nA}1R  
sHeader=httpConnection.getHeaderFieldKey(i); ,6rg00wGE  
if(sHeader!=null) xM85^B'  
{ @DK,ka(  
if(sHeader.equals("Content-Length")) Nt42v  
{ kE QT[Lo  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ,lm.~%}P*  
break; ;zI;oY#.y  
} <rc3&qmd  
} DmAMr=p  
else ,ZjbbBZ  
break; V
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} TL@_m^SM  
} xy`aR< L  
catch(IOException e){e.printStackTrace ();} (1\!6  
catch(Exception e){e.printStackTrace ();} qA:CV(Z  
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Utility.log(nFileLength); *=}$@OS  
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return nFileLength; cT^,[3i:c  
} 8YFfnk  
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//保存下载信息（文件指针位置） reLYtv  
private void write_nPos() #:L|-_=a  
{ M$A"<5  
try{ ^.j
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output = new DataOutputStream(new FileOutputStream(tmpFile)); y|V/xm+Fp  
output.writeInt(nStartPos.length); Bn*D<<{T  
for(int i=0;i<nStartPos.length;i++) 5{qFKo"g@,  
{ ch,<4E/c[R  
// output.writeLong(nPos); O?NAbxkp  
output.writeLong(fileSplitterFetch.nStartPos); Q)yhpwrX  
output.writeLong(fileSplitterFetch.nEndPos); Q(gu";&  
} OtJYr1:y_  
output.close(); 2-nL2f!a{p  
} tDFN *#(  
catch(IOException e){e.printStackTrace ();} N8:?Z#z  
catch(Exception e){e.printStackTrace ();} C/%umazP9  
} \p1H" A  
@P+k7"f  
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//读取保存的下载信息（文件指针位置） a?E]-Zf  
private void read_nPos() qQ%zSJ?  
{ punc'~  
try{ #B:J7&@fn  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ')I/
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int nCount = input.readInt(); RvV4SlZz
 
nStartPos = new long[nCount]; w(n&(5FzB<  
nEndPos = new long[nCount]; -QCo]:cp  
for(int i=0;i<nStartPos.length;i++) "t~I;%$[  
{ ?I)-ez  
nStartPos = input.readLong(); t`+x5*gW  
nEndPos = input.readLong(); |ap{+ xh  
} UZMo(rG.]{  
input.close(); EaFd1  
} ^"K
 
catch(IOException e){e.printStackTrace ();} zMt"ST.  
catch(Exception e){e.printStackTrace ();} T^S|u8f  
} eV^@kI4  
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private void processErrorCode(int nErrorCode) d /&aC#'B  
{ =|S8.|r+  
System.err.println("Error Code : " + nErrorCode); z,}1K!  
} O\pqZ`E=s  
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6 +^V  
//停止文件下载 4?g~GI3  
public void siteStop() o1MI&}r  
{ uNl<=1  
bStop = true; PHi'&)|  
for(int i=0;i<nStartPos.length;i++) Mkko1T=6  
fileSplitterFetch.splitterStop(); ?(>7v[=iT  
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} !V$nU8p|  
} fo&q/;l\  
//负责部分文件的抓取 ,W5pe#n  
**FileSplitterFetch.java Crh5^?  
*/ AUcq\Ys  
package NetFox; KMhoG.$Ra  
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import java.io.*; u!oHP  
import java.net.*; 7'7bIaJk  
'IFbD["r  
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public class FileSplitterFetch extends Thread { (' /S~  
{}N*e"<O  
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String sURL; //File URL HB{w:  
long nStartPos; //File Snippet Start Position zN#$eyt  
long nEndPos; //File Snippet End Position xO9,,w47  
int nThreadID; //Thread's ID FT/H~|Z>  
boolean bDownOver = false; //Downing is over g10$pf+L  
boolean bStop = false; //Stop identical c~ l$_A  
FileAccessI fileAccessI = null; //File Access interface bPC {4l  
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- 4'yp  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException *y5d&4G2  
{ 91E!4t
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this.sURL = sURL; l6Ze6X I  
this.nStartPos = nStart; KArf:d  
this.nEndPos = nEnd; qnyFRPC  
nThreadID = id; '`T.K<  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 LT!.M m  
} u]@``Zb|  
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public void run() D@^ r  
{ 6|X  
while(nStartPos < nEndPos && !bStop) {G&K_~Vj  
{ j^llO1i/  
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try{ yrR<F5xge  
URL url = new URL(sURL); v[e$
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); g v&xC 6>  
httpConnection.setRequestProperty("User-Agent","NetFox"); L7G':oA_`p  
String sProperty = "bytes="+nStartPos+"-"; x@m"[u  
httpConnection.setRequestProperty("RANGE",sProperty); ]]d9\fw  
Utility.log(sProperty); #AyM!  
}%| (G[  
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InputStream input = httpConnection.getInputStream(); V7N8m<Tf  
//logResponseHead(httpConnection); qXt2m  
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$
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byte[] b = new byte[1024]; *hF5cM[  
int nRead; 6NZ3(   
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) qdCa]n!d  
{ r|fJ~0z  
nStartPos += fileAccessI.write(b,0,nRead); 1'"o; a]k/  
//if(nThreadID == 1) 1FjA  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); R/~j <.s3P  
} UB|Nx(V s  
2Q|Vg*x\U  
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Utility.log("Thread " + nThreadID + " is over!"); 4Yt:PN2  
bDownOver = true; (toGU  
//nPos = fileAccessI.write (b,0,nRead); Dgc[WsCEW  
}  M)Yu^  
catch(Exception e){e.printStackTrace ();} W
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} bo$xonV@y  
} `;(/Wh  
TA`*]*O(  
#`:60#l  
//打印回应的头信息 /]>&OSV  
public void logResponseHead(HttpURLConnection con) *;m5^i<,;S  
{ Pgr>qcbql  
for(int i=1;;i++) _Eq:Qbw#  
{ k^C;"awh  
String header=con.getHeaderFieldKey(i); d{9rEB?  
if(header!=null) [bJ"*^M)  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); NqkRR$O  
Utility.log(header+" : "+con.getHeaderField(header)); !!o69  
else UQPd@IVu6  
break; VaZS_qGe:  
} 9C-F%te7  
} :?@d\c'  
'|J-8"  
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public void splitterStop() hAfRHd  
{ yHCQY4/  
bStop = true; lh7{2WQ  
} ^-4mZXAy1|  
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} !g=
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/* WT'P[RU2  
**FileAccess.java Rk"VFe
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*//文件访问(定位，写) '}P)iS2  
package NetFox; }UXj|SY  
import java.io.*; z\_q`43U7  
x2Y1B  
Tx/  
public class FileAccessI implements Serializable{ miZ
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WE|L{  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 v^[tK2&v  
RandomAccessFile oSavedFile; &^ =t%A%#  
long nPos; NvJu)gI%  
>
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public FileAccessI() throws IOException X2dTV}~i  
{ T"kaOy  
this("",0); ?Sn$AS I  
} fa\<![8LAU  
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public FileAccessI(String sName,long nPos) throws IOException ^=OjsN

 
{ x"8(j8e  
oSavedFile = new RandomAccessFile(sName,"rw"); ;NLL?6~  
this.nPos = nPos; >5/dmHPc  
oSavedFile.seek(nPos); ukS@8/eJ  
} *r:8=^C7S  
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public synchronized int write(byte[] b,int nStart,int nLen) zclt2?  
{ "h$A.S  
int n = -1; =<`9T_S 16  
try{ o6xl,T%  
oSavedFile.write(b,nStart,nLen); 1kb?y4xeJ  
n = nLen; =zqOkC h$  
} e`k 2g^  
catch(IOException e) ZS>}NN  
{ 2~R"3c+^  
e.printStackTrace (); )P:TVe9`  
} ^q FFF3<8  
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return n; O:xRUjpL  
} qZKU=HM  
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} l:j9lBS  
1
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$w+g%y)  
/* [g&Q_+,j  
**SiteInfoBean.java Wj.)wr!  
*/ `5[VO  
package NetFox; <^n9?[m*  
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public class SiteInfoBean { ?ohLcz  
s67$tlV  
3_^w/-7`B  
private String sSiteURL; //Site's URL @_1$ <8  
private String sFilePath; //Saved File's Path ;&Eu<%y  
private String sFileName; //Saved File's Name &>L\unS  
private int nSplitter; //Count of Splited Downloading File [A*vl9=  
N5%~~JRO  
t8]u#bx"?  
public SiteInfoBean() pOIFO=k  
{//nSplitter的缺省值为5 t(p  
//default value of nSplitter is 5 W 86S)+h  
this("","","",5); 9XobTi3+'  
} Ujq)h:`  
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[OH>NpL  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) /YUf('b  
{ GlQ=M)E  
sSiteURL= sURL; /\ ~{  
sFilePath = sPath; ;PG
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sFileName = sName; PJO;[: .I  
this.nSplitter = nSpiltter; cX*  
1;.}u=8  
PeTA:MW  
} >tib21*  
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public String getSSiteURL() <XCH{Te1  
{ X903;&Cim  
return sSiteURL; Oo rH  
} 9Ki86  
%4n=qK9T5  
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public void setSSiteURL(String value) I0Wn?Qq=@  
{ LT'#0dCC  
sSiteURL = value; oY+RG|j@  
} RoJ&dK  
Sq(=Bn6E  
-#rFCfPy^  
public String getSFilePath() {a%T <WW  
{ r~t&;yRv  
return sFilePath; L d#  
} G@,qO#5&  
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public void setSFilePath(String value) .JQR5R |Q  
{ }c&Zv#iO6  
sFilePath = value; I&1Mh4yu  
} H(?z?2b p  
s2w.V O  
dQ;rO$co  
public String getSFileName() Dk]Y\:  
{ 7J$ ^R6rh  
return sFileName; G V0q?  
} OP:;?Fs9`  
"#[Y[t\Ia  
li/O&@g`  
public void setSFileName(String value) 9dKrE_zK:  
{ 7
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sFileName = value; V4VTP]'n  
} %o^'(L@z  
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9D8el}uHf  
public int getNSplitter() 0B3*\ H}5  
{ 9RR1$( f  
return nSplitter; U R@'J@V#:  
} yVh]hL#4+w  
8iX?4qj{P  
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public void setNSplitter(int nCount) o
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{ tYmWze.
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nSplitter = nCount; !^`ZHJ-3>;  
} zFQxW4G  
} o @&#*3<_e  
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TS=p8@w}  
/* -Frx{3  
**Utility.java $:mCyP<y  
*/ UXIq>[2Z1  
package NetFox; S'TF7u  
+-8uIqZ  
pN%L3?2  
public class Utility { v?d~H`L  
] J:^$]  
dc%+f  
public Utility() v*3ezf\  
{ fE_QB=9 cz  
% YU(,83(+  
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} S ._9  
=I7#Vtd^K<  
//线程睡眠 atW;S99#  
public static void sleep(int nSecond) +s_@964  
{ C=9|K`g5 R  
try{ W13$-hf9  
Thread.sleep(nSecond); H#wn3O  
} 6!b96bV  
catch(Exception e) n%Nf\z  
{ (x?A#o>%  
e.printStackTrace (); gD&%$&q
  
} y;#p=,r  
} l+YpRx/T\  
Mgf80r=  
//日志 0)9GkHVu(  
public static void log(String sMsg) "&L<u0KHG  
{ !;fkc0&!  
System.err.println(sMsg); DB%=/ \U  
} Ak>RLD25_  
,'82;oP4  
u5T\_0  
public static void log(int sMsg) i,* DWD+  
{ #4d0/28b  
System.err.println(sMsg); p&XbXg-  
} WY<ip<  
} HykJ}ezX4  
y . AN0  
l2n>Wce9  
/* ;k!Ej-(  
**TestMethod.java L`];i8=I  
*/ p[g!LD  
package NetFox; !m]76=@  
!~>u\h  
` LU&]NS3  
public class TestMethod { c3K(mM:  
bpKb<c  
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public TestMethod() nFxogCn
 
{ ///xx/weblogic60b2_win.exe sQTW?KA-Te  
try{ sA}=o.\j:  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Yckl,g_  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Pm" ,7  
SiteFileFetch fileFetch = new SiteFileFetch(bean); +F+jC9j(<  
fileFetch.start(); _(oJ8h(  
} #l{q
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catch(Exception e){e.printStackTrace ();} ~~wz05oRG  
>f}rM20Vm  
Xj|j\2$ 0  
} ' 71D:%p  
ihs@ 'jh  
)UN@|IX  
public static void main(String[] args) /Xn
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{ S@T>u,t'  
new TestMethod(); Sh{odrMj*  
} @I_A(cr  
} >W 8!YOc  
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