http断点续传简单实现（java)

/* \Oi5=,  
**SiteFileFetch.java GS$ZvO  
*/ !w @1!Xpn1  
package NetFox; =Jsg{vI  
import java.io.*; <$RS*n  
import java.net.*; _8,vk-,'  
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public class SiteFileFetch extends Thread { fBHkLRFH  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 6V.awg,  
long[] nStartPos; //开始位置
8#X?k/mzU  
long[] nEndPos; //结束位置 Qw3a"k-  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ,[Dh2fPM,  
long nFileLength; //文件长度 S4#A#a2J  
boolean bFirst = true; //是否第一次取文件 3g?MEM~  
boolean bStop = false; //停止标志 [z W_%O kP  
File tmpFile; //文件下载的临时信息 n@G:e-m{A  
DataOutputStream output; //输出到文件的输出流 \e
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 1<XiD3H;  
public SiteFileFetch(SiteInfoBean bean) throws IOException k
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{ c%q}"Y0oh  
siteInfoBean = bean; J0IdFFZ|w  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ;FV~q{  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); !L&=?CX  
if(tmpFile.exists ()) Zp/qs z(]  
{ |#DC.Ga!  
bFirst = false; 7bgnZ]r8t  
read_nPos(); \SYPu,ZT  
} &Iv\jhq  
else n;-x!Gs  
{ btUUZ"q<  
nStartPos = new long[bean.getNSplitter()]; mp&Le YYn  
nEndPos = new long[bean.getNSplitter()]; K$Mx}m7l  
} 3EbnZb  
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} O0K@M  
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public void run() U6/m_`nc  
{ :0J-ek.;  
//获得文件长度 jw`&Np2Q  
//分割文件 p
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//实例FileSplitterFetch ]ro1{wm!WU  
//启动FileSplitterFetch线程 *
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//等待子线程返回 A^T~@AO
 
try{ SX_k
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if(bFirst) <6d{k[7fz)  
{ +XU$GSw3(  
nFileLength = getFileSize(); xWC\954  
if(nFileLength == -1) 1jZDw~  
{ TS\A`{^T  
System.err.println("File Length is not known!"); Z-? Iip{  
} 9,iq"dQ  
else if(nFileLength == -2) sx;V,"Y  
{ vWnHC  
System.err.println("File is not access!"); vOvxQS}dBp  
} tj"v0u?
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else H#1*'e>  
{ Ux%\Y.PPI  
for(int i=0;i<nStartPos.length;i++) ^'C,WZt  
{ o+if%3  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 4e(9@OLP  
} ;qMnO_E  
for(int i=0;i<nEndPos.length-1;i++) eI/\I:G{f  
{ 9sfB+]}h  
nEndPos = nStartPos[i+1]; \dp9@y[^  
} yZj}EBa  
nEndPos[nEndPos.length-1] = nFileLength; ;qT!fuN;  
} (!XYH@Mz<w  
} JR? )SGB  
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//启动子线程 s60:0>  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; C]\^B6l<  
for(int i=0;i<nStartPos.length;i++) U&Sbm~Qi  
{ K=!ZI/+ju  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2-cU -i4  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 8ACYuN\  
nStartPos,nEndPos,i); \V"PmaP\  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 07T;IV3#C5  
fileSplitterFetch.start(); uDy>xJ|  
} "a0u-}/D  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ~kSnXJ
v  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); V(''p{  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ig.6[5a\  
nEndPos = " + nFileLength); lH,]ZA./  
// fileSplitterFetch[nPos.length-1].start(); +AgkPMy  
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//等待子线程结束 Fl#VKU3h  
//int count = 0; n&3iv^  
//是否结束while循环 Gw\G+T?M-  
boolean breakWhile = false; !F7EAQn{(  
9GtVI^]  
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while(!bStop) DiYJlD&  
{ t_zY0{|P  
write_nPos(); ~ ];6hxv  
Utility.sleep(500); z`xz~9a<  
breakWhile = true; jOm&yX  
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for(int i=0;i<nStartPos.length;i++) {'c%#\  
{ aoakTi!}  
if(!fileSplitterFetch.bDownOver) #8Id:56  
{ a'>$88tl  
breakWhile = false; +EiUAs~H  
break; -}N\REXE  
} q~g&hR}K  
} [!dnm1  
if(breakWhile) <R`,zE@t'(  
break; P/gb+V=g!  
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//count++; Z@.ol Y  
//if(count>4) gGiV1jN_  
// siteStop(); #*>7X>,J  
} @k:f}-t  
:AqnWy  
1<qVN'[  
System.err.println("文件下载结束！"); .X<"pd*@e  
} 0LHiOav  
catch(Exception e){e.printStackTrace ();} RESGI}
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} "13 :VTs[5  

#/B~G.+(  
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//获得文件长度 IYM@(c@ld0  
public long getFileSize() `~aLSpB65  
{ u>Axq3F  
int nFileLength = -1; -B3wRAEt  
try{ 9i2vWSga  
URL url = new URL(siteInfoBean.getSSiteURL()); XvzV lKL  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ?/l}(t$H  
httpConnection.setRequestProperty("User-Agent","NetFox"); iz  GaV[  
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int responseCode=httpConnection.getResponseCode(); ZAo)_za&mH  
if(responseCode>=400) Y%?!AmER  
{ vu.S>2Wv  
processErrorCode(responseCode); s!o<Pd yJK  
return -2; //-2 represent access is error X$9D0;L  
} E~Up\f  
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String sHeader; k0e|8g X  
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for(int i=1;;i++) [>Kxm  
{ b1>$sPJ+  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 4qSS<SqY  
//Utility.log(in.readLine()); qYu!:xa8  
sHeader=httpConnection.getHeaderFieldKey(i); (krG0S:0Q  
if(sHeader!=null) RH'F<!p  
{ TNPGw!  
if(sHeader.equals("Content-Length")) FO'. a  
{
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); m1$P3tZPn  
break; VzYP:QRz  
} ,YMdXYu`s  
} S5pP"&I[  
else u,SX`6%  
break; 8DS5<  
} p2NB~t7Z  
} @%@^5  
catch(IOException e){e.printStackTrace ();} _]r)6RT  
catch(Exception e){e.printStackTrace ();} Bzy=@]`  
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Utility.log(nFileLength); E~g}DKs_5  
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return nFileLength; k;:u| s8NS  
} 36Z`.E>~L  
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//保存下载信息（文件指针位置） AO7qs:+  
private void write_nPos() +q=jB-eIx  
{ S~(VcC$K  
try{ <$3nD b-  
output = new DataOutputStream(new FileOutputStream(tmpFile)); . ;@)5"  
output.writeInt(nStartPos.length); B?YfOSF=5  
for(int i=0;i<nStartPos.length;i++) W%XS0k}x  
{ gMK3o8B/  
// output.writeLong(nPos); #/v_h6$  
output.writeLong(fileSplitterFetch.nStartPos); Tx?@*Q  
output.writeLong(fileSplitterFetch.nEndPos); e4W];7_K!  
} 4!s k3Cw{  
output.close(); .W+4sax:  
} i K[8At"Xo  
catch(IOException e){e.printStackTrace ();} Di1G  
catch(Exception e){e.printStackTrace ();} B l/e>@M  
} z` ?xS  
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//读取保存的下载信息（文件指针位置） jeBj   
private void read_nPos() I/-w65J]  
{ C
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try{ z`:^e1vG  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); gGdYh.K&e5  
int nCount = input.readInt(); W
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nStartPos = new long[nCount]; S"A
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nEndPos = new long[nCount]; C`_D{r  
for(int i=0;i<nStartPos.length;i++) 5F+ f'~  
{ ! tP
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nStartPos = input.readLong(); ,v5>sL  
nEndPos = input.readLong(); [^=8k2  
} 0|Ft0y`+  
input.close(); !9cPNIi  
} 9C~GL,uKs  
catch(IOException e){e.printStackTrace ();} n
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catch(Exception e){e.printStackTrace ();} :Du{8rV  
} u]-El}*[  
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private void processErrorCode(int nErrorCode) <0qY8  
{ ]
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System.err.println("Error Code : " + nErrorCode); l YA+k5  
} %|* y/m  
k#+^=F^)I  
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//停止文件下载 R#bV/7Ol  
public void siteStop() B=/=U7T  
{ &>4$ [m>n  
bStop = true; daJ-H  
for(int i=0;i<nStartPos.length;i++) so&3A&4cL  
fileSplitterFetch.splitterStop(); acZ|H  
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} l+X^x%EA  
} Sh6 NgO  
//负责部分文件的抓取 ct/THq  
**FileSplitterFetch.java Z$K%@q,10+  
*/ {cHTg04  
package NetFox; K{h]./%  
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import java.io.*; DYk->)   
import java.net.*; /38Pp%
 
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public class FileSplitterFetch extends Thread { (8F?yBu  
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String sURL; //File URL F+^[8zK^  
long nStartPos; //File Snippet Start Position a2)*tbM9\  
long nEndPos; //File Snippet End Position >'g60R[  
int nThreadID; //Thread's ID ]>!_OCe&  
boolean bDownOver = false; //Downing is over V0B4<TTAo~  
boolean bStop = false; //Stop identical T js{ )r9  
FileAccessI fileAccessI = null; //File Access interface ]V\g$@  
52Ffle8  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException GDe$p;#"9g  
{ Y mSaIf  
this.sURL = sURL; 2uB26SEIl  
this.nStartPos = nStart; U.
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this.nEndPos = nEnd; "d*  
nThreadID = id; dQo$^?  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 `u)V9{  
} goWt!,&f  
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public void run() X,Q(W0-6$u  
{ 0drc^rj !  
while(nStartPos < nEndPos && !bStop) >CA1Ub&ls  
{ 9{&x-ugM  
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try{ v3]M;Y\  
URL url = new URL(sURL); N#qoKY(#  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wOSNlbQ5jl  
httpConnection.setRequestProperty("User-Agent","NetFox"); #jR?C9&!(  
String sProperty = "bytes="+nStartPos+"-"; 9$t@Gmn  
httpConnection.setRequestProperty("RANGE",sProperty); wIPDeC4  
Utility.log(sProperty); ,peFNpi  
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InputStream input = httpConnection.getInputStream(); v2SsfhT  
//logResponseHead(httpConnection); S+ x[1#r  
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8 F 1ga15  
byte[] b = new byte[1024]; KJ |1zCM  
int nRead; *V+fRN4 W  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) \8H"lcj:  
{ oOw"k*,h:S  
nStartPos += fileAccessI.write(b,0,nRead); Cq'r 'cBZ  
//if(nThreadID == 1) lTNkmQ  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 9EQ,|zf'  
} |MGw$  
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Utility.log("Thread " + nThreadID + " is over!"); OTm"Iwzu@  
bDownOver = true; Ds$;{wl#x  
//nPos = fileAccessI.write (b,0,nRead); F U%b"gP^  
} 6 >2! kM7  
catch(Exception e){e.printStackTrace ();} zj}efv<e  
} w}0P
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} =!2  
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//打印回应的头信息 U^S0H(>  
public void logResponseHead(HttpURLConnection con) gnec#
j  
{
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for(int i=1;;i++) T
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{ A#{*A  
String header=con.getHeaderFieldKey(i); \>Q,AyL  
if(header!=null) ul1Vsj  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); +z_0?x  
Utility.log(header+" : "+con.getHeaderField(header)); #YV;Gp(2h  
else P
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break; / ffWmb_4  
} EJsb{$u  
} ""=Vt]  
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public void splitterStop() A1@a:P=  
{ C.Yz<?;S  
bStop = true; `W=JX2I  
} eAEVpC2  
q S
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} 6I<`N  
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/* T/nRc_I+^B  
**FileAccess.java 6{ Eh={:b  
*//文件访问(定位，写) 1U!CD-%(  
package NetFox; 5,3h'\ "!  
import java.io.*; 
'>8N'*  
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public class FileAccessI implements Serializable{ Tbw8#[6AX  
6kk(FVX  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 dc
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RandomAccessFile oSavedFile; 3FfS+q*3S  
long nPos; p_( NLJ%  
 lwlR"Z  
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public FileAccessI() throws IOException n$8A"'.M  
{ ] N8V?.|:  
this("",0); }OZfsYPz}T  
} d p].FS  
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public FileAccessI(String sName,long nPos) throws IOException d4U_Wu&  
{ aE}u5L$#  
oSavedFile = new RandomAccessFile(sName,"rw"); {Ffr l(*  
this.nPos = nPos; bk2vce&  
oSavedFile.seek(nPos); "lm3o(Dk  
} &^"m6  
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k
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public synchronized int write(byte[] b,int nStart,int nLen) `Bx CTwc  
{ 4R.#=]F  
int n = -1; )!Bv8&;e  
try{ kK(,FB  
oSavedFile.write(b,nStart,nLen); e): &pqA  
n = nLen; ! d(,t[cV  
} 3z#16*  
catch(IOException e) KR63W:Z\'  
{ fjf\/%  
e.printStackTrace (); *e=e7KC6kI  
} RN;Tqq):  
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return n; 6b0#z#E  
} #gP\q?5Ov  
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} =619+[fK  
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/* Yd9y8TqJ  
**SiteInfoBean.java I#0$5a},u^  
*/ LY7'wONx  
package NetFox; (_D#gr{S=  
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public class SiteInfoBean { <D?`*#K  
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private String sSiteURL; //Site's URL '<O& :  
private String sFilePath; //Saved File's Path -7u4f y{T  
private String sFileName; //Saved File's Name *ZRQ
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private int nSplitter; //Count of Splited Downloading File ~*RNJ  
h c"n?  
3OTSLF/  
public SiteInfoBean() #'8E%4  
{//nSplitter的缺省值为5 \;~>AL*  
//default value of nSplitter is 5 -LF^u;s8&S  
this("","","",5); Tg[+K+b  
} qzXch["So  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Y|Z*|c.4OK  
{ n/?_]  
sSiteURL= sURL; *
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sFilePath = sPath; @f5X AK?  
sFileName = sName; o(}vR<tD\  
this.nSplitter = nSpiltter; TMbj]Mso  
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} h[Hw9$31  
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>-Jutr<I"~  
public String getSSiteURL() ,>)/y
  
{ m}k rG  
return sSiteURL; Rh%x5RFFc  
} *@dqAr%  
t>^A
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public void setSSiteURL(String value) ;s{rJG{inG  
{ SNcaIzbr  
sSiteURL = value; +<I>]J2  
} 1^vN?#Kt  
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4Vh#Ye:`  
public String getSFilePath() `CO?} rW  
{ f>dWl$/_s  
return sFilePath; 7JjTm^bu  
} mIt=r_
  
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!-[e$?-  
public void setSFilePath(String value) rB-&'#3%  
{ ~
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sFilePath = value; wPOQy~:  
} %Z
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public String getSFileName() Z{|wjZb(  
{ XK>B mq/]  
return sFileName; {qK>A?
9  
} )D Y?Y-n  
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public void setSFileName(String value) kLK}N>
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{ V|Smk;G  
sFileName = value; oJEind>8O  
} JS}iNS'X  
D >$9(  
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public int getNSplitter() aVEg%8  
{ ;BsyN[bF  
return nSplitter; w!7Hl9BW  
} Z
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public void setNSplitter(int nCount) pxjb^GZ0  
{ 7xqTT
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nSplitter = nCount; a%cCR=s=  
} JHBX'1GQa  
} sSU p7V  
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/* n'>`2 s  
**Utility.java [WW3'= e^  
*/ [5yLg  
package NetFox; w,n&K6<  
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public class Utility { [7oU =  
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public Utility() Jsde+G,N  
{ -pvF~P?8U  
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} u[k0z!p_ c  
yL{X}:;}  
//线程睡眠 (hr*.NS#  
public static void sleep(int nSecond) 9l<f?OzAO  
{ ~qekM>z  
try{ P :zZ  
Thread.sleep(nSecond); nB>C3e  
} {B+|",O5)  
catch(Exception e) _HjS!(lMk  
{ ;W 16Hr Z  
e.printStackTrace (); #l2KJ7AMK  
} CEzwI _  
} cgY+xd@  
-*HR0:H  
//日志 F/}(FG<'>I  
public static void log(String sMsg) WTK )SKa,.  
{ W!6&T [j>  
System.err.println(sMsg); &V"9[0  
} P3Ocfpf Bp  
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public static void log(int sMsg) PaIE=Q4gJ  
{ O(pa;&"  
System.err.println(sMsg); U~H]w,^  
} .d/e?H:  
} ,%Sf,h?"^  
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w`ebZa/j  
/* ?y"=jn  
**TestMethod.java ;l4epN  
*/ rs`"Kz`(  
package NetFox; O7,)#{  
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<9Sg,ix't  
public class TestMethod { \?EnTu.  
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public TestMethod() dK.k,7R  
{ ///xx/weblogic60b2_win.exe AXN%b2  
try{ m6+4}=Cn  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); B\*"rSP\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ebv"`0K$  
SiteFileFetch fileFetch = new SiteFileFetch(bean); KF!?;q0J  
fileFetch.start(); A*b>@>2  
} T*pcS'?'  
catch(Exception e){e.printStackTrace ();} ,.6)y1!  
:^bjn3b  
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} Ga,+  
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public static void main(String[] args) 0*y|k1  
{ %0&c0vT  
new TestMethod(); MVDEVq0  
} 0vYHx V  
} MeCHn2zwB  
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