http断点续传简单实现（java)

/* 4@mso+tk  
**SiteFileFetch.java T$IUKR  
*/ D$mf5G &  
package NetFox; DUhT>,~]  
import java.io.*; &\c5!xQ9*  
import java.net.*; 4a?r` '  
#?Wo <]i  
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public class SiteFileFetch extends Thread { hRLKb}  
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SiteInfoBean siteInfoBean = null; //文件信息Bean oAaf)?8  
long[] nStartPos; //开始位置 ^9s"FdB]24  
long[] nEndPos; //结束位置 ~Zu}M>-^c,  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ;&q]X]bJ  
long nFileLength; //文件长度 Ym`1<2mq\  
boolean bFirst = true; //是否第一次取文件 W}?s^  
boolean bStop = false; //停止标志 2$3kKY6$e  
File tmpFile; //文件下载的临时信息 ]Cr]Pvab{  
DataOutputStream output; //输出到文件的输出流 jQkUNPHu  
}I)z7l.  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） pKnIQa[c  
public SiteFileFetch(SiteInfoBean bean) throws IOException l:x_j\  
{ Lj
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siteInfoBean = bean; <0>[c<{V<  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); UFL0K  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); c<>y!^g  
if(tmpFile.exists ()) ~n8F7  
{ VD9J
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bFirst = false; 1P \up  
read_nPos(); l%@dE7<&#Z  
} 5/k
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else @T_O6TcY  
{ -C=]n<ak  
nStartPos = new long[bean.getNSplitter()]; K: 4P;ApI  
nEndPos = new long[bean.getNSplitter()]; uZ-`fcCjD  
} dhs#D:/{9  
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} D?%e"*>  
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public void run() uFWvtL?;_  
{ 5"[yFmP*  
//获得文件长度 VSx%8IM+X  
//分割文件 vmMV n-\#  
//实例FileSplitterFetch A=W5W5l(>  
//启动FileSplitterFetch线程 \ x:_*`fU  
//等待子线程返回 ~yd%~|  
try{ XQ4dohGCP  
if(bFirst) c_t7RWV}  
{ Y5Ft96o))x  
nFileLength = getFileSize(); 7f[8ED[4  
if(nFileLength == -1) z(#=tC|  
{ [rc'/@
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System.err.println("File Length is not known!"); UJ
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} [O [FCn  
else if(nFileLength == -2) '8L(f w{k  
{ :C>
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System.err.println("File is not access!"); o%$<LaQG5  
} =>P_mPP=  
else 5=*@l  
{ p FXd4*  
for(int i=0;i<nStartPos.length;i++) ~T;K-9R  
{ X4XFu  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); e W9)@nVJ  
} ~>4@;  
for(int i=0;i<nEndPos.length-1;i++) E*h0#m|)  
{ bU:V%B?=]  
nEndPos = nStartPos[i+1]; Z"
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} p_A5C?&  
nEndPos[nEndPos.length-1] = nFileLength; 4{g:^?1=  
} N"&$b_u[  
} 8xc8L1;  
Wn2Ny jX  
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//启动子线程 5f/@:~  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; x_]",2 W'  
for(int i=0;i<nStartPos.length;i++) |:dCVd<du  
{ \YjB+[.  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3x,Aczb  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 4
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nStartPos,nEndPos,i); XryQ)x(  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @"jmI&hYn  
fileSplitterFetch.start(); 2LtU;}7s  
} {K<~ vj;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), *;>V2!N=U  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); nomu$|I  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", InAU\! ew  
nEndPos = " + nFileLength); yp( ?1  
// fileSplitterFetch[nPos.length-1].start(); WT;.>F  
X
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//等待子线程结束 V< 2IIH5^  
//int count = 0; 0F-mROC=F  
//是否结束while循环 ]JkpRaP$  
boolean breakWhile = false; -lnTYxo+]^  
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while(!bStop) G~Sy&XJuq  
{ ,?P8m"  
write_nPos(); `;zu1o  
Utility.sleep(500); eTLI/?|+N  
breakWhile = true; 50}.Xm@,BO  
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for(int i=0;i<nStartPos.length;i++) eA3`]XP.`b  
{ B
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if(!fileSplitterFetch.bDownOver) ]C9%]`  
{ ;9 =}_h)]  
breakWhile = false; QwKky ^A  
break; h v;n[  
} aNuZ/9O  
} Ak<IHp^Q  
if(breakWhile) dj8F6\  
break; buMiJzU  
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@n5;|`)\  
//count++; *[XN.sb8E  
//if(count>4) 7I@9v=xV  
// siteStop(); AH"g^ gw~T  
} /1[}G
!  
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System.err.println("文件下载结束！"); bCJ<=X,g`K  
} X}n&`y{/  
catch(Exception e){e.printStackTrace ();} 1]a*Oer}  
} ;'b!7sMO~  
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b/a?\0^  
//获得文件长度 6E)uu; 8  
public long getFileSize() F^/~@^{P  
{ 1t~S3Q||>]  
int nFileLength = -1; o|b[(t$;O  
try{ "@UU[o  
URL url = new URL(siteInfoBean.getSSiteURL()); $1Q3Y'Q9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); F&nMI:h7  
httpConnection.setRequestProperty("User-Agent","NetFox"); ~Q.8 U3"  
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int responseCode=httpConnection.getResponseCode(); u&l>cJ'
 
if(responseCode>=400) *SMoodFBS  
{ |j.KFu845  
processErrorCode(responseCode); e+d6R[`M  
return -2; //-2 represent access is error dQWA"6?i  
} <;TP@-a  
;XKo44%  
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String sHeader; ;T"m[D  
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for(int i=1;;i++) "63zc1  
{ )cv0$  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); v4Fnh`{  
//Utility.log(in.readLine()); 79<9}<T  
sHeader=httpConnection.getHeaderFieldKey(i); $_I%1  
if(sHeader!=null) !h`cXY~w  
{ _{Fdw  
if(sHeader.equals("Content-Length")) K~fDv
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{ s%S_K  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); \( Gf+  
break; ],fwZd[t  
} Uy_}@50"l  
} I;kUG_c(4  
else P?3YHa^up  
break; ZmR[5 mv@  
} h[[/p {z  
} h~=\/vF  
catch(IOException e){e.printStackTrace ();} x]mye  
catch(Exception e){e.printStackTrace ();} /4wm}g9  
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Utility.log(nFileLength); [][:/~q!  
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return nFileLength; 709Uv5  
} JQ{zWJlt  
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#:Sy`G6!?  
//保存下载信息（文件指针位置） U#~nN+SIt  
private void write_nPos() Ilt L@]e  
{ 0.{oA`5N  
try{ FRJ:ym=E  
output = new DataOutputStream(new FileOutputStream(tmpFile)); e{rHO,#A>  
output.writeInt(nStartPos.length); 3ZJagJ\O  
for(int i=0;i<nStartPos.length;i++) zDGg\cPj9  
{ k_|v)\4B  
// output.writeLong(nPos); \4`saM /x  
output.writeLong(fileSplitterFetch.nStartPos); 7}iewtdy,  
output.writeLong(fileSplitterFetch.nEndPos); ixI5Xd<  
} B3g82dm  
output.close(); 9-Nq[i"  
} :vgh KI  
catch(IOException e){e.printStackTrace ();} JK'_P}[]I  
catch(Exception e){e.printStackTrace ();} R1b )  
} tr9_bl&z  
y u
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//读取保存的下载信息（文件指针位置） < 4EB|@E  
private void read_nPos() *F%ol;|Q  
{ &:e}4/G  
try{ D0E"YEo\nv  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 6UzT]"LR;  
int nCount = input.readInt(); j O5:{%  
nStartPos = new long[nCount]; 2'UFHiK  
nEndPos = new long[nCount]; n\8[G[M  
for(int i=0;i<nStartPos.length;i++) @qr3v>3X<  
{ E't G5,/m  
nStartPos = input.readLong(); lo]B5_en  
nEndPos = input.readLong(); ~"<VUJ=Ly:  
} p?`|CE@h7  
input.close(); L_zmU_zD  
} [Yahxw}  
catch(IOException e){e.printStackTrace ();}  j5VRv$P  
catch(Exception e){e.printStackTrace ();} lWyP[>*  
} 2I(@aB+  
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private void processErrorCode(int nErrorCode) S
1^Mw;?P  
{ glKs8^W  
System.err.println("Error Code : " + nErrorCode); YV_I-l0  
} />2$ XwP  
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//停止文件下载 j}?ZsnqV  
public void siteStop() .X=M!  
{ .T$9Q Ar5  
bStop = true; VOF:+o@.  
for(int i=0;i<nStartPos.length;i++) YQ8x6AJ  
fileSplitterFetch.splitterStop(); Gp3t?7S{T  
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} ^N}~U5  
} 1r:fxZO\Vd  
//负责部分文件的抓取 4uAb LSh9  
**FileSplitterFetch.java g]#zWTw(   
*/ 8wx#,Xa  
package NetFox; =iN_Ug+  
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import java.io.*; o? xR[N-J  
import java.net.*; bHH}x"d[x  
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public class FileSplitterFetch extends Thread { JU2' ~chh  
)yH#*~X_  
I:>d@e/;  
String sURL; //File URL <x;[ H%  
long nStartPos; //File Snippet Start Position VA r?teY  
long nEndPos; //File Snippet End Position uKAHJ$%  
int nThreadID; //Thread's ID _G8y9!J  
boolean bDownOver = false; //Downing is over WxP4{T* <  
boolean bStop = false; //Stop identical $6?KH7lA  
FileAccessI fileAccessI = null; //File Access interface jw%FZ  
#FDu4xi  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException z^GGJu%vjr  
{ h|>n3-k|p  
this.sURL = sURL; jnLu|W&  
this.nStartPos = nStart; o!dkS/u-m  
this.nEndPos = nEnd; = Ow&UI  
nThreadID = id; DmpJzHj|  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ]8cX#N,M  
} g$+O<a@n  
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public void run() KNyD}1  
{ S5 oHe4#89  
while(nStartPos < nEndPos && !bStop) |;1:$E"  
{ l:C0:m%  
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try{ ,&l*AB!  
URL url = new URL(sURL); lVBy&f  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); bL#TR;*]  
httpConnection.setRequestProperty("User-Agent","NetFox"); fOfz^W  
String sProperty = "bytes="+nStartPos+"-"; NP(?[W  
httpConnection.setRequestProperty("RANGE",sProperty); }z2-|"H  
Utility.log(sProperty); :[?o7%"  
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2/gj@>dt  
InputStream input = httpConnection.getInputStream(); T`DlOi]Z_  
//logResponseHead(httpConnection); ^?0,G>I
%-  
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byte[] b = new byte[1024]; 2Rp{]s$jo  
int nRead; M@86u^80  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) yBjWPx?  
{ ]OUOL/J  
nStartPos += fileAccessI.write(b,0,nRead); 0#nXxkw  
//if(nThreadID == 1) X)+sHcE~#  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); vPq\reKe  
} PvCE}bY{}  
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Utility.log("Thread " + nThreadID + " is over!"); KT?s\w  
bDownOver = true; qq{N; C  
//nPos = fileAccessI.write (b,0,nRead); qk"=nAJX  
} jJnBwHp  
catch(Exception e){e.printStackTrace ();} i58CA?  
} Yx/~8K_%M?  
} .`=PE&xq  
 } R6h  
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//打印回应的头信息 D[y|y3F  
public void logResponseHead(HttpURLConnection con)
3&2q\]Y,  
{ b,A1(_pzi  
for(int i=1;;i++) 5Rp2O4Z  
{ tzN;;h4C  
String header=con.getHeaderFieldKey(i); 6$.Xj\zl  
if(header!=null) z,P7b]KVe  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); O|m-k0n  
Utility.log(header+" : "+con.getHeaderField(header)); dgD%
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else q &o=4  
break; LJ#P- `!{&  
} e-meUf9  
} ];]EK6dzG  
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public void splitterStop() :Djp\ e6!  
{ SSC!BcC1  
bStop = true; MUl+Oy>  
} b=l}|)a  
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} l.)!jWY  
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/* #| Po&yu4R  
**FileAccess.java +rX,Sl`/  
*//文件访问(定位，写) U#4W"1~iX  
package NetFox; %;J`dM  
import java.io.*; ".Ug A\0  
wQ.zj`?$(  
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public class FileAccessI implements Serializable{ tB7aHZ|  
m%3Kq%?O  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 6w,xb&S  
RandomAccessFile oSavedFile; ITiw) M  
long nPos; t,6=EK*3T  
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public FileAccessI() throws IOException \ed(<e>  
{ NQD b;5:  
this("",0); n-_w0Y  
} ~?r6Ax-R  
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public FileAccessI(String sName,long nPos) throws IOException c6|&?}F  
{ jL1UPN  
oSavedFile = new RandomAccessFile(sName,"rw"); eu;^h3u;b  
this.nPos = nPos; ~3 (>_r  
oSavedFile.seek(nPos); ha5\T'  
} "$Q Gifb  
G7?EaLsfQ  
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public synchronized int write(byte[] b,int nStart,int nLen) V5MbWXgR  
{ &jcr7{cD  
int n = -1; g!uhy}  
try{ C5z4%,`f  
oSavedFile.write(b,nStart,nLen); Af~AE2b3"  
n = nLen; n
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} F\;1:y~1  
catch(IOException e) 3u<2~!sR  
{ jF8ld5|_|  
e.printStackTrace (); ^;d;b<  
} 5KzU&!Zh9  
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return n; XJ+sm^`vOf  
} lki(_@3  
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} /~:ztv\$M"  
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/* QPnc "!  
**SiteInfoBean.java o^D
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*/ UpbzH(?#  
package NetFox; ^.Q),{%Xo  
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public class SiteInfoBean { joq ;N]S  
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private String sSiteURL; //Site's URL 9w1)Mf}  
private String sFilePath; //Saved File's Path RA}PM?D/  
private String sFileName; //Saved File's Name ~n?U{ RmH  
private int nSplitter; //Count of Splited Downloading File 5:wf"3%%  
i2DR}%U  
)? xg=o/?  
public SiteInfoBean() I g`#U~  
{//nSplitter的缺省值为5 -zt\weqA  
//default value of nSplitter is 5 G>j/d7  
this("","","",5); f 36rU  
} dO2cgY}  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 4(NI-|q0  
{ yd k  
sSiteURL= sURL; @gd-lcMYW  
sFilePath = sPath; PNq#o%q  
sFileName = sName;  f!<mI8H  
this.nSplitter = nSpiltter; Kmtr.]Nj  
ts ] +W!:  
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} I`|>'$E[r  
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public String getSSiteURL() 8cHZBM7'  
{ iZUBw  
return sSiteURL; Y:wds=lA  
} a[/p(O  
pw,.*N3P  
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public void setSSiteURL(String value) F#hM S<  
{ _+U`afV  
sSiteURL = value; Pdv&X*
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} &8N\ 6K=  
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5g=" #  
public String getSFilePath() ],LOkAX  
{ 2:]Sy4K{  
return sFilePath; 0o#lB^e;l  
} 5v]x
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6-oQs?  
` H"5nQRV  
public void setSFilePath(String value) [4gv_g  
{ 8/=2N  
sFilePath = value; +1rJ;G  
} '{|87kI  
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public String getSFileName() #(7OvW+y  
{ ]b[3 th*  
return sFileName; }.
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} %V$^CWOy  
hX^XtIC=  
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public void setSFileName(String value) *Q)
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{ )_BteLo-  
sFileName = value; ?
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} )TLDNpH?J  
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public int getNSplitter() Uc/%4Gx  
{ v;OA hFr|  
return nSplitter; I;No++N0  
} 3[c54S+(U  
^Tl|v'   
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public void setNSplitter(int nCount) MT3UJ6~P  
{ rC'97`!K  
nSplitter = nCount; g}f@8;TY  
} ;;2s{{(R  
} 4"GY0) Q  

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=lzjMRX(?  
/* a^CIJ.P2  
**Utility.java J[^-k!9M  
*/ vnKUD
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package NetFox; (h E^<jNR  
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[[Z*n/tr  
public class Utility { $+Xohtt  
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#jnb6v=5v  
public Utility() cc@y  
{ TG!sck4/-Q  
n|8fdiK#}  
/m%;wH|6%  
} +Ix;~  
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//线程睡眠 CrK}mbe  
public static void sleep(int nSecond) s8R.?mhH=  
{ Z/%>/  
try{ Hi )n]OE  
Thread.sleep(nSecond); rK"x92P0  
} wz'D4B  
catch(Exception e) rUlXx5f  
{ ?8`b  
e.printStackTrace (); d5h:py5  
} 5Ba eHzI  
} SlmgFk!r!  
Z5v\[i
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//日志 SoCa_9*X  
public static void log(String sMsg) ;XANIT

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{ Nl0*"}`I_  
System.err.println(sMsg); }e1f kjWk  
} h]I ^%7  
$~_TE\F1  
:X+7}!Wlo  
public static void log(int sMsg) &)1+WrU  
{ KZ&{Ya  
System.err.println(sMsg); SDZ/r
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} j2V^1  
} WxFVbtw  
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/* iOw'NxmY  
**TestMethod.java GP1b/n3F1  
*/
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package NetFox; L\o-zNY  
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public class TestMethod { G8j$&1`:
 
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public TestMethod() V
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{ ///xx/weblogic60b2_win.exe x:GuqE  
try{ qEE V
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); NU O9,  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); }
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SiteFileFetch fileFetch = new SiteFileFetch(bean); 6VW&An[6r  
fileFetch.start(); +hGr2%*0f  
} ;~F&b:CyG  
catch(Exception e){e.printStackTrace ();} kyMWO*>|  
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} mqQN*.8*  
(*F/^4p!$  
("?V
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public static void main(String[] args) ><^ ,  
{ O(#DaFJv  
new TestMethod(); icH\(   
} ^i:%0"[*^i  
} qi!+Ceo}  
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