http断点续传简单实现（java)

/* SVJt= M  
**SiteFileFetch.java mo  
*/ 8\B]!  
package NetFox; Gx/kel[Y}  
import java.io.*; @z1pE@7jK  
import java.net.*; kYnp$8  
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public class SiteFileFetch extends Thread { &^1{x`Qo=  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 1X
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long[] nStartPos; //开始位置 }\3
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long[] nEndPos; //结束位置 cPbAR'  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ?3Y~q;I]O  
long nFileLength; //文件长度 c
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boolean bFirst = true; //是否第一次取文件 %E*Q0/  
boolean bStop = false; //停止标志 o#9Q   
File tmpFile; //文件下载的临时信息 /;clxtus  
DataOutputStream output; //输出到文件的输出流 c4Wl^E8  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） r%412#  
public SiteFileFetch(SiteInfoBean bean) throws IOException ]mT2a8`c.r  
{ \_l4li  
siteInfoBean = bean; Q7@oAeNd  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); fF]w[lLDv  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); /
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if(tmpFile.exists ()) Z)'gj  
{ ne9- c>>  
bFirst = false; Z,1b$:+  
read_nPos(); ~>B`T%=H  
} pi;'!d[l%  
else =:;K nS  
{ Wf:LYL  
nStartPos = new long[bean.getNSplitter()]; pX?/=T@ Bw  
nEndPos = new long[bean.getNSplitter()]; ,jq:%Y[KZ  
} gi #dSd1\&  
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} *~0U4kw+  
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public void run() 14z ?X%  
{ 9|NH5A"H.  
//获得文件长度 ?4cj
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//分割文件 \qz! v  
//实例FileSplitterFetch vo>i36  
//启动FileSplitterFetch线程 {@ Z=b5/P  
//等待子线程返回 oe<DP7e  
try{ a4\j.(w)$D  
if(bFirst) E{BX $R_8  
{ YDYN#Ob(;  
nFileLength = getFileSize(); ,#U[
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if(nFileLength == -1) W^YaC (I  
{ 8F9x2CM-[C  
System.err.println("File Length is not known!"); $0XR<D  
} wDDNB1_E  
else if(nFileLength == -2) NOFuX9/'w  
{ apZPHau6h  
System.err.println("File is not access!"); }inV)QQ  
} =z[$o9  
else %U6A"?To  
{ DIw9ov>k  
for(int i=0;i<nStartPos.length;i++) y}1Pc
*  
{ *-(8Z>9  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 7#(0GZN9h%  
} se=;vp]3a  
for(int i=0;i<nEndPos.length-1;i++) Xm3r)Bm'3  
{ (7Ln~J*  
nEndPos = nStartPos[i+1]; pGd@%/]AO  
} Zm*qV!  
nEndPos[nEndPos.length-1] = nFileLength; ,ygUy]  
} "h-ZwL  
} _p^$.\k"  
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L%jIU<?Z7  
//启动子线程 3JEg3|M(  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Ey=ymf.}  
for(int i=0;i<nStartPos.length;i++) qe'RvBz  
{ 7n,=`0{r  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Y_)xytJ$  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), +U)4V}S)  
nStartPos,nEndPos,i); q_cP<2`@V  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1my1m  
fileSplitterFetch.start(); 8SA" bH:  
} ?Wc+ J4  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), [kf6bf@  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ^.9DfA0  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ?j&ZzK'#^  
nEndPos = " + nFileLength);  |A\o  
// fileSplitterFetch[nPos.length-1].start(); Eq|5PE^7  
}N&?8s=  
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//等待子线程结束 _y&XFdp  
//int count = 0; td7Of(k'  
//是否结束while循环 sI.p( -KQ  
boolean breakWhile = false; 0O[le*3b  

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while(!bStop) ;Yt+{pI  
{ %JgdLn
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write_nPos(); ~ #7@;C<nt  
Utility.sleep(500); v*OV\h.  
breakWhile = true; !_FTy^@c2  
cy
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for(int i=0;i<nStartPos.length;i++) *d`KD64  
{ bp<,Xfl  
if(!fileSplitterFetch.bDownOver) zhJ0to[%?  
{ 5|cRHM#  
breakWhile = false; "j&'R#$&d  
break; Zrp-Hv27,,  
} xS>vmnW  
} \d*ts(/a*  
if(breakWhile) \~g,;>%7Y  
break; S*gm[ZLQ  
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//count++; \E[6wB>uN%  
//if(count>4)
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// siteStop(); r@/@b
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} =?Ui(?tI  
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System.err.println("文件下载结束！"); zk"8mTg  
} 9)t[YE:U3!  
catch(Exception e){e.printStackTrace ();} @]]&^ 7  
} Z~<=I }@  
~>N63I6  
*AP"[W  
//获得文件长度 jZC[_p;  
public long getFileSize() JEaTDV_  
{ d14n
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int nFileLength = -1; o2'Wu:Y"  
try{ _-3n'i8  
URL url = new URL(siteInfoBean.getSSiteURL()); 0n'vF&E8  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ?O3d Sxi  
httpConnection.setRequestProperty("User-Agent","NetFox"); <nb%$2r1  
\Z,{De%  
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int responseCode=httpConnection.getResponseCode(); `a!9_%|8  
if(responseCode>=400) Rj4C-X4=  
{ M
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processErrorCode(responseCode); M9""(`U  
return -2; //-2 represent access is error T9XUNR{&  
} 5\= y9Z- x  
N.H<'Q8&  
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String sHeader; O@4J=P=w  
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for(int i=1;;i++) M9afg$;.xe  
{ V[uSo$k+>  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); nmts% u  
//Utility.log(in.readLine()); Q4hY\\Hi  
sHeader=httpConnection.getHeaderFieldKey(i); R :(-"GW'  
if(sHeader!=null) L
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{ q2s
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if(sHeader.equals("Content-Length")) E3l*_b0  
{ pB
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); +wJ!zab`  
break; /Q3\6DCl  
} 0Sz[u\w  
} +'-.c"  
else vg5_@7  
break; \PU
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} O$}.b=N9  
} 3z(4axH'  
catch(IOException e){e.printStackTrace ();} S1I.l">P  
catch(Exception e){e.printStackTrace ();} k=[s%O6H  
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Utility.log(nFileLength); n=bdV(?4  
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return nFileLength; 8*@{}O##  
} huS*1xl  
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//保存下载信息（文件指针位置） IhBc/.&RL  
private void write_nPos() p7@R+F\.};  
{ [!yA#{xl,  
try{ ]/H6%"CTa  
output = new DataOutputStream(new FileOutputStream(tmpFile)); /KX+'@  
output.writeInt(nStartPos.length); ($kw*H{Ah^  
for(int i=0;i<nStartPos.length;i++) \0d'y#Gp*  
{ tV
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// output.writeLong(nPos); W.?/p~  
output.writeLong(fileSplitterFetch.nStartPos); "I)zi]vk  
output.writeLong(fileSplitterFetch.nEndPos); ,!b<SQ5M  
} |5tZ*$nGa  
output.close(); &=BzsBh  
} ?KOw~-u  
catch(IOException e){e.printStackTrace ();} eu9*3'@A  
catch(Exception e){e.printStackTrace ();} GPK\nz
}  
} vM6W64S  
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//读取保存的下载信息（文件指针位置） } P ,"  
private void read_nPos() N UX |  
{ QJRnpN/
 
try{ #$-E5R;x  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); - ~|Gwr"  
int nCount = input.readInt(); >#x[qX  
nStartPos = new long[nCount]; =uH2+9.  
nEndPos = new long[nCount]; {V2"Pym?  
for(int i=0;i<nStartPos.length;i++) ]FZPgO'G  
{ y'`/^>.  
nStartPos = input.readLong(); ft6)n T/"&  
nEndPos = input.readLong(); 8zD>t~N2C  
} xF8n=Lc  
input.close(); cQyN@W  
} 0^gY4qx[u  
catch(IOException e){e.printStackTrace ();} 1wKXOy=v0  
catch(Exception e){e.printStackTrace ();} ^]nLE]M  
} rBNVI;JZW  
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private void processErrorCode(int nErrorCode) ]*\MIz{56'  
{ hj9TiH/+  
System.err.println("Error Code : " + nErrorCode); &Y=0 0  
} @m9pb+=v  
q\?s<l63  
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//停止文件下载 $TXxhd 6  
public void siteStop() 8YQuq.(>a  
{ {:K_=IRZ  
bStop = true; 0_gN]>,9n  
for(int i=0;i<nStartPos.length;i++) p35=CX`T.  
fileSplitterFetch.splitterStop(); 5'I+%66?h$  
/;#kV]nF  
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} oCaYmi=:  
} J8alqs7  
//负责部分文件的抓取 + U5Q/g  
**FileSplitterFetch.java ,G

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*/ QDg5B6>$  
package NetFox; _|#abLh%  
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import java.io.*; lx%c&~.DiB  
import java.net.*; d#
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public class FileSplitterFetch extends Thread { \Y)HSJR;e  
%Hbq3U30  
112WryS  
String sURL; //File URL qjP~F  
long nStartPos; //File Snippet Start Position
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long nEndPos; //File Snippet End Position 6:#o0OeBP  
int nThreadID; //Thread's ID WMf / S"=  
boolean bDownOver = false; //Downing is over (@+pz/  
boolean bStop = false; //Stop identical CUI3^;&S  
FileAccessI fileAccessI = null; //File Access interface {5E8eQ  
bE !SW2:M  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Yub}AuU`v  
{ S{+t>en  
this.sURL = sURL; x|0C0a\"A  
this.nStartPos = nStart; 2`$*HPj+G  
this.nEndPos = nEnd; f=F:Af!  
nThreadID = id; A*y4<'}<  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 89FAh6uE  
} Xxg|01  
V/ G1C^'/  
.KA-=$~J1  
public void run() bkV<ZUW|;  
{ >zW2w2O3  
while(nStartPos < nEndPos && !bStop) j~-N2b6z  
{ Dt: Q$  
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try{ [gmov)\c  
URL url = new URL(sURL); #KJ# 1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 'v6@5t19j  
httpConnection.setRequestProperty("User-Agent","NetFox"); UA6id|G  
String sProperty = "bytes="+nStartPos+"-"; ttsR`R1.k  
httpConnection.setRequestProperty("RANGE",sProperty); lvke!~#  
Utility.log(sProperty); V!He2<  
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InputStream input = httpConnection.getInputStream(); '? 5
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//logResponseHead(httpConnection); el9P@r0  
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'  
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byte[] b = new byte[1024]; = j1Jl^[  
int nRead; Fc5.?X-  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) X,k^p[Rcu  
{ O+}py{ st  
nStartPos += fileAccessI.write(b,0,nRead); N#T'}>ty  
//if(nThreadID == 1) V+E8{|dYL  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8Sr'  
} {v|!];i  
^1S{::  
+F8{4^w1  
Utility.log("Thread " + nThreadID + " is over!"); z{rV|vQ  
bDownOver = true;
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//nPos = fileAccessI.write (b,0,nRead); <1
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} Tx;a2:6\[  
catch(Exception e){e.printStackTrace ();} 7?Wte&C];p  
} ..)J6L5l  
} $l]:2!R  
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k H.dtg_  
//打印回应的头信息 r:g\  
public void logResponseHead(HttpURLConnection con) f$C{Z9_SX  
{ EqW~

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for(int i=1;;i++) 1+FVM\<&  
{ q?}C`5%D  
String header=con.getHeaderFieldKey(i);  k[r^@|  
if(header!=null) vE:*{G;Y  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); k
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Utility.log(header+" : "+con.getHeaderField(header)); EQm{qc;  
else &: Q'X  
break; 6.D|\;9{c  
} cpdESc9W  
} W8d-4')|  
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public void splitterStop() \Bo%2O%4  
{ k1wIb']m]z  
bStop = true; ,s[%
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} >rd#,r  
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} wMW<lT=;  
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/* .?:*0
 
**FileAccess.java ?M4o>T%p"  
*//文件访问(定位，写) #t ;`  
package NetFox; ]fM|cN8(zM  
import java.io.*; ;{ifLI0#  
s)1-xA{'.  
@2>UR9j  
public class FileAccessI implements Serializable{ F/oqYk9`  
{MgRi7  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 b84
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RandomAccessFile oSavedFile; yvd)pH<a2  
long nPos; 5BVvT `<  
[^qT?se{  
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public FileAccessI() throws IOException o2!738  
{ T9nb ~P[  
this("",0); ? :H+j6+f  
} S{=5nR9j  
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public FileAccessI(String sName,long nPos) throws IOException ~5KcbGD~  
{ b80#75Bj>  
oSavedFile = new RandomAccessFile(sName,"rw"); Y(PCc}/\  
this.nPos = nPos; *#=Ijr~  
oSavedFile.seek(nPos); nR_Zrm  
} :G _  
q'mh*  
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public synchronized int write(byte[] b,int nStart,int nLen) F1Z'tj
j+  
{ LF7-??'  
int n = -1; oZBD.s  
try{ &6sF wK  
oSavedFile.write(b,nStart,nLen); *9'3 `^l  
n = nLen; @:>"VP<(  
} hYJzF.DW<$  
catch(IOException e) u$T]A8e  
{ U=n7RPw  
e.printStackTrace (); <,} h8;Fr  
} xC`!uPk/pL  
Q %o@s3~O  
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return n; :iE b^F}  
} `ASDUgx Mq  
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} JS/'0.  
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j9 nw,x
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/* [^hW>O=@TN  
**SiteInfoBean.java xM jn=\}  
*/ @| z _&E  
package NetFox; ~c)&9'  
26j<>>2  
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public class SiteInfoBean { (`.# n3{  
h:4(Gm;  
}*:3]  
private String sSiteURL; //Site's URL j`_S%E%X  
private String sFilePath; //Saved File's Path @A,8>0+  
private String sFileName; //Saved File's Name +CSpL2@  
private int nSplitter; //Count of Splited Downloading File o~LJ+m6-)  
]_s3<&R  
]1 f^ SxSI  
public SiteInfoBean() f+Y4~k  
{//nSplitter的缺省值为5 8C3k: D[  
//default value of nSplitter is 5 2-4N)q  
this("","","",5); rq%]CsRY5  
} zhn?;Fi  
|*bUcS<S  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) "to!&@I| 4  
{ {nmG/dn{  
sSiteURL= sURL; ^'X I%fEf  
sFilePath = sPath; MLDzWZ~}ef  
sFileName = sName; =KPmZ,/w  
this.nSplitter = nSpiltter; w"R<8e=  
,.)wCZ,wca  
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} Ks.b).fH  
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public String getSSiteURL() qTuR[(  
{ tT]@yo|?e/  
return sSiteURL; 6"-$WUlg  
} j<^!"_G]*?  
5%,3)H{;t  
r^ r+
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public void setSSiteURL(String value) _}R$h=YD  
{ ^6W}ZLp  
sSiteURL = value; k~[jk5te  
} #49l\>1z  
H{}&|;0  
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public String getSFilePath()  Zmu  
{ B}"R@;N  
return sFilePath; 3fOOT7!FL  
} MzvhE0ab  
#cY[c1cNv  
/zIG5RK>  
public void setSFilePath(String value) kz=ho~ @  
{ *V&M5  
sFilePath = value; :2/L1A)O  
} NM. e4  
o0r&w;!  
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public String getSFileName() IyO0~Vx>  
{ 4%0s p  
return sFileName; hW*o;o7u  
} <'\Nv._2a  
u&~Xgq5[  
5_9`v@-4_  
public void setSFileName(String value) w{tA{{  
{ A{_CU-,  
sFileName = value; v47' dC  
} J jAxNviG  
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V!:!c]8F  
public int getNSplitter() e:G~P u`  
{ ai 4k?  
return nSplitter; eT%x(P
 
} D,IT>^[^7  
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public void setNSplitter(int nCount) >DRxF5b{  
{ @5Tl84@Q  
nSplitter = nCount; \;7U:Y$v  
} !8@yi"n  
} P>_O :xD  
2Bt/co-~4  
yi8vD~aA[  
/* tw4,gW  
**Utility.java _9BL7W $;  
*/ czRBuo+k+  
package NetFox; 9R=avfI  
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public class Utility { "kApGNB  
=z}PR1X!  
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public Utility() ~~yng-3)1  
{ ~<k>07  
"dpjxH=xO  
A f`Kg-c_(  
} CaYb}.:AX  
e=LrgRy+  
//线程睡眠 )?{<Tt@  
public static void sleep(int nSecond)
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{ 9d1km~  
try{ c =m#MMc)  
Thread.sleep(nSecond); NVzo)C8kb  
} :'DX M{  
catch(Exception e) r
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{ (^yaAy#4  
e.printStackTrace (); :>!-[hfQ  
} RxP~%oADw  
} 4QQt 0u0  
vU%o5y:  
//日志 d- ZUuw  
public static void log(String sMsg) +
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{ 45biy(qa  
System.err.println(sMsg); X1w11Z7o  
} $z!G%PO1%  
H:~bWd'iz  
8cO?VH,nk  
public static void log(int sMsg) 1e\cJ{B  
{ [>NMuwtG  
System.err.println(sMsg); %Za}q]?  
} IYn`&jS{  
} )B]"""J  
5=;cN9M@  
|ts0j/A]Pi  
/* ]{=y8]7  
**TestMethod.java -gGw_w?)(  
*/ 2>jk@~Z1:u  
package NetFox; +xuv+mo  
X&[Zk5DU*  
/J^dzvH  
public class TestMethod { 23CvfP  
!WXV1S  
Nd(3q]{  
public TestMethod() +VVn@=&?  
{ ///xx/weblogic60b2_win.exe ">T\
]V$R  
try{ -+F,L8  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); &/m^}x/_W  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); !=S?*E +j)  
SiteFileFetch fileFetch = new SiteFileFetch(bean); o"Xv)#g&  
fileFetch.start(); ^m7y=CJM  
} 4lPO*:/  
catch(Exception e){e.printStackTrace ();} 0$Tb5+H5  
QP~["%}T  
bEF2-FO  
} Fepsa;\sU  
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;tQc{8O6L  
public static void main(String[] args) pYcs4f!?p  
{
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new TestMethod(); Zf>:h   
} r!b>!  
} QE/kR!r  
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