http断点续传简单实现（java)

/* 2~!+EH  
**SiteFileFetch.java lm(k[]@  
*/ 1y6{3AZm<  
package NetFox; Qr]`flQ8  
import java.io.*; u\}"l2 r  
import java.net.*; Y2P%0
 
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public class SiteFileFetch extends Thread { !^(?C@TQ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean L%0G >2x  
long[] nStartPos; //开始位置 Hge0$6l  
long[] nEndPos; //结束位置 hH=}<@z   
FileSplitterFetch[] fileSplitterFetch; //子线程对象 *ta?7uSiT  
long nFileLength; //文件长度 @SH$QUM(  
boolean bFirst = true; //是否第一次取文件 Wt9'-"c  
boolean bStop = false; //停止标志 7G &I]>  
File tmpFile; //文件下载的临时信息 Huho|6ohH  
DataOutputStream output; //输出到文件的输出流 Et+WLQ6)  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） C?7I(b:  
public SiteFileFetch(SiteInfoBean bean) throws IOException Cc>+OUL  
{ Tj,1]_`=V$  
siteInfoBean = bean; &265 B_'D  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));  ^#&:-4/  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); P^& =L&U  
if(tmpFile.exists ()) (@;=[5+  
{ #@K %Mx  
bFirst = false; @hj5j;NHK  
read_nPos(); Ggp.%kS6F  
} q;=!=aRg  
else ?bH!|aW(H  
{ /nVGr]t_pj  
nStartPos = new long[bean.getNSplitter()]; |lVoL.Z,0  
nEndPos = new long[bean.getNSplitter()]; \"?5CHz*  
} }(Dt,F`  
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} FR? \H"'x  
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public void run() >}6V=r3[+  
{ 5 p! rZ  
//获得文件长度 \ 3HB  
//分割文件 zpBkP-%}E  
//实例FileSplitterFetch 2(K@V6j$M  
//启动FileSplitterFetch线程 8)51p+a
 
//等待子线程返回 <5:`tC2  
try{ ><3!J+<?  
if(bFirst) D:vX/mf;7  
{ ~mK|~x01@  
nFileLength = getFileSize(); aXRf6:\%  
if(nFileLength == -1) e)A-.SRiO$  
{ J0O wzO  
System.err.println("File Length is not known!"); acdF5ch@  
} ="__*J#nze  
else if(nFileLength == -2) Rr6}$]1  
{ g]E>e v{`  
System.err.println("File is not access!"); xdkC>o4>  
}  mPS27z(  
else \O(~:KN  
{ .<kbYo:MV  
for(int i=0;i<nStartPos.length;i++) QeNN*@ ='i  
{ _2E*  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); #/LU@+  
} fsz:A"0H  
for(int i=0;i<nEndPos.length-1;i++) jltW@co2sV  
{ 0mi$_Ld+  
nEndPos = nStartPos[i+1]; o2e gNTG  
} +jN%w{^=  
nEndPos[nEndPos.length-1] = nFileLength; Z[?zaQ$  
} .}ePm(  
} ~"}o^#@DwJ  
Z,}c)  
@z1pE@7jK  
//启动子线程 kYnp$8  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; y,cz;2  
for(int i=0;i<nStartPos.length;i++) u;3wg`e  
{ )0N^rw kW  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), >dYN@cB$}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), #[ ?E,  
nStartPos,nEndPos,i); y';"tDFb  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); $s"{C"4q  
fileSplitterFetch.start(); } za"rU  
} Z|6,*XEc   
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), =Cg1I\  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); bTbF  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", UNJAfr P  
nEndPos = " + nFileLength); 1Zt>andBF  
// fileSplitterFetch[nPos.length-1].start(); -cP7`.a  

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//等待子线程结束 $i]G'fj  
//int count = 0; AtYqD<hl:  
//是否结束while循环 Vh'
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boolean breakWhile = false; SBh"^q  
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while(!bStop) GiS:Nq`$(  
{ C q)Cwc[H  
write_nPos(); G;Py%8  
Utility.sleep(500); 4c9a"v  
breakWhile = true; r}i}4
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for(int i=0;i<nStartPos.length;i++) pX?/=T@ Bw  
{ ,jq:%Y[KZ  
if(!fileSplitterFetch.bDownOver) :b`ywSp`  
{ I#PhzGC@  
breakWhile = false; vtF|:
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break; EaKbG>  
} i)th] 1K%  
} *~0U4kw+  
if(breakWhile) l?)!^}Qc  
break; @RXkj-,eC#  
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//count++; uZe"M(3r$  
//if(count>4) 6<mlx'  
// siteStop(); yZQcxg%  
} PWk\#dJN&  
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System.err.println("文件下载结束！"); hMnm>  
} ;b_l/T(  
catch(Exception e){e.printStackTrace ();} i!;9A6D  
} zEk/15  
,{X}C  
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//获得文件长度 YF)k0bu&;  
public long getFileSize() apZPHau6h  
{ }inV)QQ  
int nFileLength = -1; =z[$o9  
try{ eI,H  
URL url = new URL(siteInfoBean.getSSiteURL()); 2{<o1x,Ym  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |8?e4yVd  
httpConnection.setRequestProperty("User-Agent","NetFox"); Zygu/M6  
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int responseCode=httpConnection.getResponseCode(); E
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if(responseCode>=400) {"c`k4R  
{
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processErrorCode(responseCode); -G(#,rXk  
return -2; //-2 represent access is error n?*r,)'  
} spT$}F2n  
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String sHeader; H3LuRGe&2  
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for(int i=1;;i++) Cy dV$!&mP  
{ '0w</g  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ());  0*E_D  
//Utility.log(in.readLine()); Q^bYx (r5w  
sHeader=httpConnection.getHeaderFieldKey(i); {mUt|m7!  
if(sHeader!=null) gI!d*]{BP  
{ 055C1RV%  
if(sHeader.equals("Content-Length")) n8tw8o%&[  
{ %n6NVi_[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); /@B2-.w  
break; }N&?8s=  
} (hEg
&@  
} _y&XFdp  
else u+^KP>rM(  
break; 8u%,5GV>Xr  
} yLPP6_59$  
} 09qfnQG  
catch(IOException e){e.printStackTrace ();} [&g"Z"  
catch(Exception e){e.printStackTrace ();} ,0c]/Sd*p  
WLA&K]  
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Utility.log(nFileLength); U(Tl$#Bt  
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return nFileLength; /_qHF-  
} #Vu;R5GZ}  
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//保存下载信息（文件指针位置） W-*HAS  
private void write_nPos() T%Bz>K  
{ l(W?]{C[%  
try{ 8L+A&^qx  
output = new DataOutputStream(new FileOutputStream(tmpFile)); y^z c@f  
output.writeInt(nStartPos.length); QQHQ3\  
for(int i=0;i<nStartPos.length;i++) N0%q66]1  
{ ZZL@UO>:  
// output.writeLong(nPos); a@J/[$5  
output.writeLong(fileSplitterFetch.nStartPos); n =WH=:&  
output.writeLong(fileSplitterFetch.nEndPos); TOhWfl;  
} mfG m>U  
output.close(); Gu@C*.jj!  
} zdw* ?C  
catch(IOException e){e.printStackTrace ();} wX$|(Y}  
catch(Exception e){e.printStackTrace ();} Zl>dB
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} Ot)S\s>  
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//读取保存的下载信息（文件指针位置） .9N7`  
private void read_nPos() >bd@2au9!  
{ ~sZ$`t
 
try{ U>OAtiq JX  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); I,<?Kv  
int nCount = input.readInt(); =Z{jc  
nStartPos = new long[nCount]; ?J,,RK.  
nEndPos = new long[nCount]; @meT8S9t  
for(int i=0;i<nStartPos.length;i++) 2W2T  
{ ?T.=ym  
nStartPos = input.readLong(); &_u.q/~  
nEndPos = input.readLong(); a#k7 aOT0  
} ,i1BoG  
input.close(); &=MVX>[  
} ^/6P~iK'  
catch(IOException e){e.printStackTrace ();} I)yF!E &  
catch(Exception e){e.printStackTrace ();} k~gOL#$  
} XK\3"`kd  
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private void processErrorCode(int nErrorCode) 1=7ASS9  
{ UhrRB  
System.err.println("Error Code : " + nErrorCode); eWNg?*/  
} CmV &+C$V%  
R7U%v"F>`  
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//停止文件下载 uT'l.*W6i  
public void siteStop() ];lZ:gT  
{ e#,(a  
bStop = true; [sjkm+ ?  
for(int i=0;i<nStartPos.length;i++) % P Ex  
fileSplitterFetch.splitterStop(); zj(V\y&H  
#]6{>n1*+w  
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} ma+AFCi  
} &x[7?Y L  
//负责部分文件的抓取 0#DE
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**FileSplitterFetch.java :o .+<_&  
*/ =JW-EQ6[T  
package NetFox; !><asaB]1  
;-XfbqZ\  
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import java.io.*; \1LfDlQk)  
import java.net.*; o<%0|n_O&  
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public class FileSplitterFetch extends Thread { #4b]j".P!n  
w#[cGaIB  
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String sURL; //File URL R^$|D)(  
long nStartPos; //File Snippet Start Position ;Xy=;Z.]
i  
long nEndPos; //File Snippet End Position huS*1xl  
int nThreadID; //Thread's ID kaXq.  
boolean bDownOver = false; //Downing is over pmvd%X\f  
boolean bStop = false; //Stop identical ];4!0\M
 
FileAccessI fileAccessI = null; //File Access interface U: Wet,  
rv(?%h`  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :>2wVN&\c  
{ !&>`  
this.sURL = sURL; (/N&_r4x  
this.nStartPos = nStart; q:TNf\/o  
this.nEndPos = nEnd; .1jiANY  
nThreadID = id; "GQ Q8rQ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 %^HE^
&  
} 9i}$245lB  
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public void run() uBa<5YDF  
{ |Ia9bg'1U  
while(nStartPos < nEndPos && !bStop) p/?o^_s  
{ 3_Xu3hNH!  
>>,G3/Zd*  
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try{ w\YS5!P,V  
URL url = new URL(sURL); UJSIbb5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 8Z
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httpConnection.setRequestProperty("User-Agent","NetFox"); Bskp&NV':  
String sProperty = "bytes="+nStartPos+"-"; ,`Y$}"M4  
httpConnection.setRequestProperty("RANGE",sProperty); >*8V]{f9  
Utility.log(sProperty); SXZ9+<\  
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>e>3:~&2  
InputStream input = httpConnection.getInputStream(); NeG`D'  
//logResponseHead(httpConnection); (pd$?vRy  
&<]f-  
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byte[] b = new byte[1024]; H{vKk  
int nRead; lQHF=Jex  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) X<}}DZSu a  
{ Ly+UY.v"  
nStartPos += fileAccessI.write(b,0,nRead); _E`+0;O
 
//if(nThreadID == 1) <3x%-m+p4  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Ze eV-  
}
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@%R4V[Lo.  
Utility.log("Thread " + nThreadID + " is over!"); `a4&_`E,p  
bDownOver = true; 5b7(^T^K  
//nPos = fileAccessI.write (b,0,nRead); hOUH1m.  
} 'UIFP#GtFO  
catch(Exception e){e.printStackTrace ();} o5tCbsHj-  
} Mh
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} fw jo?  
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//打印回应的头信息 |(z{)yWbC[  
public void logResponseHead(HttpURLConnection con) b4
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{ %-540V{q  
for(int i=1;;i++) *y?HaU  
{ p8~lGuH  
String header=con.getHeaderFieldKey(i); !%,7*F(  
if(header!=null) jU j\<aW  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); P3&s<mh  
Utility.log(header+" : "+con.getHeaderField(header)); ORs:S$Nt$  
else A_zCSRF,  
break; BB/wL_=:  
} i D IY|  
} tF`L]1r>  
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public void splitterStop() h#
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{ _xaum  
bStop = true; {r&mNbz  
} 6:#o0OeBP  
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} t<p#u=jOa  
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/* [Y .8C$0  
**FileAccess.java K$,Zg  
*//文件访问(定位，写) 5wx_ol}2  
package NetFox; JY#vq'dl|  
import java.io.*; yS W$zA,  
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public class FileAccessI implements Serializable{ [<RhaZz  
x|~8?i$%  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 &)1.z7T  
RandomAccessFile oSavedFile;  !Ld5Y$  
long nPos; u?Ffqt9'  
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public FileAccessI() throws IOException ,<
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{ h+Co:pr  
this("",0); Z@0tZ^V{  
} ?.46X^  
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public FileAccessI(String sName,long nPos) throws IOException 7 m{lOR  
{ !cyrt<  
oSavedFile = new RandomAccessFile(sName,"rw"); '? 5
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this.nPos = nPos; ^5sA*%T4  
oSavedFile.seek(nPos); PXMd=,}  
} w.?4}'DK  
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]].~/kC^3k  
public synchronized int write(byte[] b,int nStart,int nLen) t`Z'TqP R  
{ %GhI0F #  
int n = -1; 1Toiqb/  
try{ P8z%*/ 3NF  
oSavedFile.write(b,nStart,nLen); ,eyh%k*hz  
n = nLen; 8_('[89m  
} u9hd%}9Qd?  
catch(IOException e) Ou_H&R  
{ q5(t2nNb  
e.printStackTrace (); M&V'*.xz  
} c;VqEpsbl  
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return n; GmHDG-  
} =0Z
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} \?xM%(:<Q  
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/* )^ah, ;
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**SiteInfoBean.java [CJ<$R !  
*/ !O_G%+>5W  
package NetFox; U]cXE1c>F  
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public class SiteInfoBean { o}rG:rhIh  
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private String sSiteURL; //Site's URL
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private String sFilePath; //Saved File's Path tMxde+$y  
private String sFileName; //Saved File's Name ZxF`i>/h  
private int nSplitter; //Count of Splited Downloading File (P|[<Sd  
G4cgY|71  
 i0=U6S:#  
public SiteInfoBean() pe?)AiTZ:  
{//nSplitter的缺省值为5 DDeU:  
//default value of nSplitter is 5 T*x2+(r  
this("","","",5); #Z%" ?RJ  
} hq=;ZI  
|7|S>h^  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) TjUwe@&Rw  
{ .?:*0
 
sSiteURL= sURL; ?M4o>T%p"  
sFilePath = sPath; #t ;`  
sFileName = sName; ]fM|cN8(zM  
this.nSplitter = nSpiltter; Z1HH0{q-A  
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} k =!
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public String getSSiteURL() yvd)pH<a2  
{ 5BVvT `<  
return sSiteURL; [^qT?se{  
} sINQ?4_8T  
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public void setSSiteURL(String value) ? :H+j6+f  
{ h4;kjr}h}  
sSiteURL = value; jK w 96  
} G2`z?);1b  
~5KcbGD~  
b80#75Bj>  
public String getSFilePath() Y(PCc}/\  
{ k\f _\pj6  
return sFilePath; meX2Y;  
} )WqolB  
/qLO/Mim  
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public void setSFilePath(String value) 'PF>#
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{ bZ`v1d (r  
sFilePath = value; (0 T!-hsP  
} Hyb(.hlZh  
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public String getSFileName() ;(i6 X)  
{ cH5i420;aO  
return sFileName; *ID=X!v  
} N~)-\T:ap  
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public void setSFileName(String value) t13V>9to  
{ \g}]u(zg%  
sFileName = value; `5Y*) q  
} ] ?DU8  
h^3gYL7O6  
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public int getNSplitter() _b&|0j:Ud  
{ ~,)jZ-fw  
return nSplitter; 6W i n!4  
} d/d)MoaJ*t  
iH(7.?.r  
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public void setNSplitter(int nCount) SXL3>-Z E  
{ {$frR "K  
nSplitter = nCount; 4"P9z}y=i  
} o 4F'z  
} SzW;Yb"#^k  
:>&q?xvA  
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/* C$w%! jE  
**Utility.java D[$"nc/  
*/ CNNqS^ct  
package NetFox; [> HKRVy  
[mtp-4*  
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public class Utility { %-n)L  
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public Utility() ](r}`u%}y  
{ Hx#YN*\.M  
?}HK!feU  
j yHa}OT  
}  S!?T0c?>  
w.m8SvS&b  
//线程睡眠 BE?]P?r?  
public static void sleep(int nSecond) pCKP{c=6Q  
{
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try{ _pdKcE\X  
Thread.sleep(nSecond); J9T2 p\5  
} 7@c!4hmr
U  
catch(Exception e) Myc-lCE  
{ P+CV4;Xz  
e.printStackTrace (); i%i~qTN  
} opa/
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} yy3rh(ea  
I!/32* s1t  
//日志 
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public static void log(String sMsg) mb*Yw6q  
{ s#$t!F??9  
System.err.println(sMsg); {it.F4.  
} +g1>h,K 3  
H!;N0",]N  
oG,>Pk
  
public static void log(int sMsg) O,%UNjx9K  
{ mE~WE+lw9  
System.err.println(sMsg); y [Vd*8  
} +<E#_)}`D6  
} P'~`2W0sz  

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/* -zK>{)Z=q  
**TestMethod.java D.
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*/ ~n 'A1  
package NetFox; I0 t#{i  
@GQe-04W`  
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public class TestMethod { +^7cS6"L  
p3P8@M  
P& 1$SWNyW  
public TestMethod() \;7U:Y$v  
{ ///xx/weblogic60b2_win.exe Cmx<>7fN  
try{ nlv,j&  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); S}C[  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 6mcb'hy  
SiteFileFetch fileFetch = new SiteFileFetch(bean); QSaDa@OV  
fileFetch.start(); JC'3x9_<z  
} SQ)BS/8A  
catch(Exception e){e.printStackTrace ();} Z `F[0-  
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} O?vh]o  
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public static void main(String[] args) S257+ K9  
{ Z=% j|xE_  
new TestMethod(); ~~yng-3)1  
} uzp\V 39  
} L@Rgiq|v-|  
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