http断点续传简单实现（java)

/* fpoH7Jd V  
**SiteFileFetch.java l:faI&o.@  
*/ #=
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package NetFox;
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import java.io.*; z<@$$Z=0UF  
import java.net.*; xaSkn  
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public class SiteFileFetch extends Thread { FRfMtx
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SiteInfoBean siteInfoBean = null; //文件信息Bean 0.+iVOz+Y  
long[] nStartPos; //开始位置 xD_jfAH'  
long[] nEndPos; //结束位置 MT
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 crvWAsm  
long nFileLength; //文件长度 .+B!mmp  
boolean bFirst = true; //是否第一次取文件 %\-+SeC  
boolean bStop = false; //停止标志 O4-UVxv}  
File tmpFile; //文件下载的临时信息 -"a])- j  
DataOutputStream output; //输出到文件的输出流 wmoOp;C  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） IkkJ4G  
public SiteFileFetch(SiteInfoBean bean) throws IOException 4+ 4?
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{ zpa'G1v  
siteInfoBean = bean; ";>D0h^D  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 7s[ ATu  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); h]'fX  
if(tmpFile.exists ())  sRoZvp5  
{ %X.Q\T  
bFirst = false; @MN>ye'T  
read_nPos(); r2xlcSn%  
} 1pz6e8p:m  
else VK|!aqA{b  
{ zu;Yw=cM)  
nStartPos = new long[bean.getNSplitter()]; iP_rEi*-J  
nEndPos = new long[bean.getNSplitter()]; 3K#e]zoI  
} &1Az`[zKGW  
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} fnXl60C%  
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public void run() C{>?~@z&5  
{ bxyU[`  
//获得文件长度 m+vwp\0  
//分割文件 p=r{ODw#3  
//实例FileSplitterFetch MM5#B!
BB  
//启动FileSplitterFetch线程 {O"dj;RU  
//等待子线程返回 mybDK'EW  
try{ T]i~GkD\  
if(bFirst) X5<L  
{ N;D+]_;0|  
nFileLength = getFileSize(); ^Cak/5^K  
if(nFileLength == -1) q?t>!1c  
{ |]B]0J#_  
System.err.println("File Length is not known!"); zd;xbH//)b  
} F,EHZ,<V  
else if(nFileLength == -2) =
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{ DSnsi@Mi  
System.err.println("File is not access!"); +B&FZ4'  
} Rdv"Aj:  
else @yek6E&9  
{ XM_S"  
for(int i=0;i<nStartPos.length;i++) hpw;w}m  
{ km3-Hp1  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); $[1 M2>[  
} _e-a>y  
for(int i=0;i<nEndPos.length-1;i++) t71 0sWh{  
{ 1-b,X]i  
nEndPos = nStartPos[i+1]; ho:,~ A;k  
} "iKK&%W  
nEndPos[nEndPos.length-1] = nFileLength; 'i@Y #F%D  
} 1`)R#$h  
} 7"S|GEs:  
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//启动子线程 |Rab'9U^  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length];
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for(int i=0;i<nStartPos.length;i++) vR`KRI`{  
{ 0Ifd!  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), +q2l,{|?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), gReaFnm  
nStartPos,nEndPos,i); RZz].Nx  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); =F:d#j>F  
fileSplitterFetch.start(); N .SszZh  
} Cvl"")ZZ`  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #ob">R  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Db3tI#  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Y${ $7+@  
nEndPos = " + nFileLength); 6Es-{u(,  
// fileSplitterFetch[nPos.length-1].start(); M`5^v0,C  
-MU^%t;-  
2R1W[,Ga!  
//等待子线程结束 \C>I6{  
//int count = 0; w.V8-9{  
//是否结束while循环 g;*~
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boolean breakWhile = false; 4f/8APA  
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while(!bStop) 5&VLq  
{ iKdC2m  
write_nPos(); O!|:
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Utility.sleep(500); &K\di*kN  
breakWhile = true; ~+|p.(I  
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for(int i=0;i<nStartPos.length;i++) %]:u^\7  
{ 0{jRXa-(  
if(!fileSplitterFetch.bDownOver) rv\<Q-uQ8  
{ 38f9jF%7j  
breakWhile = false; T}zOM%]]  
break; 2B*9]AHny  
} KBOxr5w  
} jd$lu^>I  
if(breakWhile) jaDZPX-yS  
break; nGg>lRL
  
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//count++; d
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//if(count>4)  9((v.  
// siteStop(); 6@nEcr  
} :vm*miOF  

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System.err.println("文件下载结束！"); UW40Y3W0  
} 2N>:GwN  
catch(Exception e){e.printStackTrace ();} fD V:ueO  
} xeZ,}YP)  
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//获得文件长度 0Y[mh@(  
public long getFileSize() v k<By R  
{ "tm2YUG},s  
int nFileLength = -1; =)'AXtvE  
try{ (L q^C=  
URL url = new URL(siteInfoBean.getSSiteURL()); |r6<DEg
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :Oy9`vv  
httpConnection.setRequestProperty("User-Agent","NetFox"); &i6WVNGy  
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int responseCode=httpConnection.getResponseCode(); }Vk#w%EJ  
if(responseCode>=400) `@-H ;  
{ sJMT _yt;  
processErrorCode(responseCode); c:4i&|n  
return -2; //-2 represent access is error qm]k (/w  
} 5%uLs}{\q  
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String sHeader; c]#F^(-A`  
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for(int i=1;;i++) 3)p#}_u{  
{ D O#4E<]5  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); vm 1vX;  
//Utility.log(in.readLine()); &n91f  
sHeader=httpConnection.getHeaderFieldKey(i); "Lw[ $  
if(sHeader!=null) YyjnyG  
{ M qFuZg  
if(sHeader.equals("Content-Length")) IP9mv`[  
{ Xu2:yf4No*  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); "NMX>a,(  
break; `[X5mEe  
} :$L^l{gT  
} SI^!e1@M[  
else A )tGB&  
break; -Uh3A\#(  
} sWa`-gc  
} {ZrIA+eH  
catch(IOException e){e.printStackTrace ();} zU}Ru&T9  
catch(Exception e){e.printStackTrace ();} 8t25wPlx  
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Utility.log(nFileLength); 33:{IV;k  
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return nFileLength; O3x9S,1i  
} Nb(c;|nV  
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//保存下载信息（文件指针位置） )O;6S$z9Y  
private void write_nPos() vtk0 j  
{ /m"O.17N  
try{ `bY>f_5+  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Utd`T+AF*  
output.writeInt(nStartPos.length); r01Z 0>  
for(int i=0;i<nStartPos.length;i++) !Z]#1"A8  
{ lkl+o&D9  
// output.writeLong(nPos); td@I ;d2  
output.writeLong(fileSplitterFetch.nStartPos); `n)e] dn  
output.writeLong(fileSplitterFetch.nEndPos); d< j+a1&  
} }Vjg>"  
output.close(); @{n"/6t  
} @
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catch(IOException e){e.printStackTrace ();} __LR!F]
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catch(Exception e){e.printStackTrace ();} 0wQ'~8  
} X\sOeb:]  
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//读取保存的下载信息（文件指针位置） $`;1][OD  
private void read_nPos() r}T(?KGx  
{ '1P~"P3  
try{ >h)D~U(H  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); &|MdBJ  
int nCount = input.readInt(); qca,a3k  
nStartPos = new long[nCount]; B6UTooj  
nEndPos = new long[nCount]; `X)y5*##wq  
for(int i=0;i<nStartPos.length;i++) Lp31Y .4  
{ )seeB
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nStartPos = input.readLong(); Wz{,N07Q#{  
nEndPos = input.readLong(); ^1`Mz<  
} ]WFr5  
input.close(); &"lSq2  
} kZ5;Fe\*  
catch(IOException e){e.printStackTrace ();} S,0h &A9  
catch(Exception e){e.printStackTrace ();} uE E;~`G  
} ERTjY%A  
}B1f_T  
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private void processErrorCode(int nErrorCode) o{]2W `0r  
{ Y[sBVz'j5  
System.err.println("Error Code : " + nErrorCode); +-2W{lX  
} '<=77yDg  
)>"|<h.2]  
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//停止文件下载 " l;=jk]  
public void siteStop() 7!sR%h5p  
{ QzLE9   
bStop = true; |-l9Z  
for(int i=0;i<nStartPos.length;i++) #|j8vmfn$e  
fileSplitterFetch.splitterStop(); a=_:`S]}  
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} aoUz_7  
} `_"loPu  
//负责部分文件的抓取 "50c<sZSB  
**FileSplitterFetch.java *(g0{V  
*/ eL" +_lW  
package NetFox; @oKW$\  
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import java.io.*; Yj"{aFK#u@  
import java.net.*; nixIKOnjC  
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public class FileSplitterFetch extends Thread { b9R0"w!ml  
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String sURL; //File URL `a6AES'w$  
long nStartPos; //File Snippet Start Position :P8X?C63W]  
long nEndPos; //File Snippet End Position l6T^e@*  
int nThreadID; //Thread's ID y0]"qB  
boolean bDownOver = false; //Downing is over )ko[_OJj  
boolean bStop = false; //Stop identical ]!>tP,<`'  
FileAccessI fileAccessI = null; //File Access interface yz7Fe  
()^tw5e'^  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException oL U!x
 
{ {%Rntb  
this.sURL = sURL; Cu!S|Xj.  
this.nStartPos = nStart; S'(IG m4  
this.nEndPos = nEnd; {ui{Yc  
nThreadID = id; bn:74,GeyK  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 U<|*
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} sK@]|9ciQ  
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public void run() :sX4hZK=G  
{ 9 lXnNK |]  
while(nStartPos < nEndPos && !bStop) qTz5P  
{ SFjRSMi  
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try{ *+TO%{4  
URL url = new URL(sURL); h$]nfHi_Q  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 14`S9SL{V  
httpConnection.setRequestProperty("User-Agent","NetFox"); eRm*+l|?  
String sProperty = "bytes="+nStartPos+"-"; /H*[~b  
httpConnection.setRequestProperty("RANGE",sProperty); LFAefl\  
Utility.log(sProperty); G%fXHAs.+  
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InputStream input = httpConnection.getInputStream(); P>EG;u@.  
//logResponseHead(httpConnection); cwE?+vB  
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byte[] b = new byte[1024]; q*
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int nRead;
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) jZk dTiI  
{ !{F\\D/  
nStartPos += fileAccessI.write(b,0,nRead); rRXF@  
//if(nThreadID == 1) -amNz.`[PR  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); *JOp)e0b  
} )}J}
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Utility.log("Thread " + nThreadID + " is over!"); pmiC|F83!8  
bDownOver = true; <uImZC  
//nPos = fileAccessI.write (b,0,nRead); %_(^BZd  
} qFp]jbU  
catch(Exception e){e.printStackTrace ();} GPrq(  
} /~{fPS  
} :j[=  
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//打印回应的头信息 \;Sl5*kr  
public void logResponseHead(HttpURLConnection con) w&Z.rB?  
{ 5Nt9'
"  
for(int i=1;;i++) sWq@E6,I  
{ "`V:4uz  
String header=con.getHeaderFieldKey(i); zUA -  
if(header!=null) G%dzJpC(  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Z*Fn2I4  
Utility.log(header+" : "+con.getHeaderField(header)); 0pBG^I`_  
else CN6b982&  
break; ;73{n*a$  
} `^)oVs  
} v<atic  
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public void splitterStop() :Vrj[i-{  
{ ynn>d  
bStop = true; POQ4&ChA  
} +vYVx<uTQ  
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} l Ma||  
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/* }0F
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**FileAccess.java d&X <&)a7  
*//文件访问(定位，写) A<-3u  
package NetFox; A/OGF>  
import java.io.*; yW;]J87*  
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public class FileAccessI implements Serializable{ )5x,-m@  
|iVw7M:  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 +L pMNnl6  
RandomAccessFile oSavedFile; {qFAX<{D  
long nPos; .WS7gTw  
7Pr5`#x#  
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public FileAccessI() throws IOException FD.L{  
{ 4Z/]7Ie  
this("",0); A[Vhy;xz  
} 3Ol`i$  
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6~Y`<#X5J  
public FileAccessI(String sName,long nPos) throws IOException AE4>pzBe  
{ Y~ Nt9L  
oSavedFile = new RandomAccessFile(sName,"rw"); 8'0KHn{#  
this.nPos = nPos; )z7+%nTO  
oSavedFile.seek(nPos); k&o1z'<C  
} B0!W=T\  
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public synchronized int write(byte[] b,int nStart,int nLen) $B@K  
{ A w)
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int n = -1; "0{t~?ol  
try{ T0BM:ofx  
oSavedFile.write(b,nStart,nLen); G=>LW1E|  
n = nLen; h|.*V$3  
} =mh)b]].4\  
catch(IOException e) 6}q# c  
{ Jek)`D  
e.printStackTrace (); @W!cC#u  
} D?P1\<A~  
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return n; "3VMjF\  
} E"b"VB  
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} mEsb?  
} x2z%J,z@4  
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sme!!+Rd  
/* S)*!jI  
**SiteInfoBean.java |I=\+
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*/ )-d&XN7  
package NetFox; lof}isOz  
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public class SiteInfoBean { VK?c='zg  
AME6Zu3Y  
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private String sSiteURL; //Site's URL 30$Q5]T  
private String sFilePath; //Saved File's Path <@:LONe<  
private String sFileName; //Saved File's Name \S"YLRn"  
private int nSplitter; //Count of Splited Downloading File
9h 0^_|"  
/(skIvE|  
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public SiteInfoBean() ]
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{//nSplitter的缺省值为5 Q2ky|  
//default value of nSplitter is 5 oS_<;Fj  
this("","","",5); oj~0zJI  
} OcGHMGdn  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) N;d@)h(N!  
{ *27*&&=)H  
sSiteURL= sURL; 2j7e@p
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sFilePath = sPath; _J`q\N K  
sFileName = sName; pZe:U;bb  
this.nSplitter = nSpiltter; zq&,KZ  
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} Ga}&%  
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public String getSSiteURL() 7ezf.[{R  
{ l/w<R  
return sSiteURL; f.&Y_G3a<  
} {9C+=v?  
~#jD/  
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public void setSSiteURL(String value) 4`#3p@-  
{ /|2#s%|-=  
sSiteURL = value; zg83->[  
} pg'3j3JW$  
\;Ywr3  
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public String getSFilePath() h_Cac@F0  
{ uM<6][^`  
return sFilePath; )R`w{V  
} S<V__Sv  
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p
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public void setSFilePath(String value) jTJ]: EN  
{ }{Ncww!iN  
sFilePath = value; :LwNOuavN  
} h[0,/`qb{  
:5`BhFAd  
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public String getSFileName() $G5;y>  
{ yprf `D>  
return sFileName; O
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} Xbb('MoI63  
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public void setSFileName(String value) {D jz']  
{ d M&BnI  
sFileName = value; '<C I^5^  
} |NcfR"[c  
^"h
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public int getNSplitter() \=yx~c_$L  
{ \HB4ikl  
return nSplitter; ;O2r
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} |?!Ew# w  
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a N|MB
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public void setNSplitter(int nCount) :>.~"uWo{  
{ Et=N`k_gO  
nSplitter = nCount; y+XB  
} n(gw%w+\7  
} 0vs9# <&V  
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/* Gv!* Qk4  
**Utility.java ~$N%UQn?b#  
*/ 1|VnPQqA  
package NetFox; ,?+rM ;  
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%:/_O*~)Yg  
public class Utility { mACj>0Z'  
uhFj|r$$  
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public Utility() vmW4 3K;  
{ h,q%MZ==^s  
L_.
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} VN[h0+n4Th  
/!kKL$j  
//线程睡眠 g(\FG
  
public static void sleep(int nSecond) i!jZZj-{  
{ k=<,A'y-/  
try{ \d0R&vFHQ  
Thread.sleep(nSecond); Z~tOR{q  
} zQ$*!1FmN  
catch(Exception e)
[e )j,Q1  
{ wwS{V  
e.printStackTrace (); ;/W;M> ^  
} (63_  
} FLO#!G  
)k0P' zGb  
//日志 *f:^6h  
public static void log(String sMsg) bmotR8d  
{ w<*tbq  
System.err.println(sMsg); }!\ZJoa  
} o[Yxh%T  
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public static void log(int sMsg) /'IO
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{ &inu mc  
System.err.println(sMsg); Z;bzp3v  
} 0A@'w*=  
} MJJy mi'b  
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^zHBDRsb2F  
/* NaSgK  
**TestMethod.java w4 <FC$  
*/ K*Zf^g m  
package NetFox; ~#dNGWwG  
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public class TestMethod { yc2c{<Ya5  
{[Po
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public TestMethod() [K;J#0V+&L  
{ ///xx/weblogic60b2_win.exe @CU3V+  
try{ ]:JoGGE a0  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ywpk\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 9@ 6y(#s
 
SiteFileFetch fileFetch = new SiteFileFetch(bean); (Bd8@}\u_  
fileFetch.start(); 7wsn8_n9  
} j`A%(()d  
catch(Exception e){e.printStackTrace ();}  k'X v*U  
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}

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7.$0LN/a!Z  
<\GP\G  
public static void main(String[] args) Y 9]  
{ n1`D:XrE  
new TestMethod(); G=!1P]M{  
} q'77BRD3  
} f8kPbpV,  
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