http断点续传简单实现（java)

/* k%81f'H  
**SiteFileFetch.java NXk!qGV2  
*/ p,W_'?,9  
package NetFox; <48<86TP  
import java.io.*; \}"m'(\c  
import java.net.*; >U!*y4  
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public class SiteFileFetch extends Thread { rf K8q'@  
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SiteInfoBean siteInfoBean = null; //文件信息Bean xge7r3i  
long[] nStartPos; //开始位置 [(mlv42"  
long[] nEndPos; //结束位置 3iX?~  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 |U'I/A  
long nFileLength; //文件长度 svhI3"
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boolean bFirst = true; //是否第一次取文件 kxB.,'  
boolean bStop = false; //停止标志 [iS$JG-  
File tmpFile; //文件下载的临时信息 }JgYCsF/f  
DataOutputStream output; //输出到文件的输出流 8|g<X1H{M  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） }IaA7f  
public SiteFileFetch(SiteInfoBean bean) throws IOException ]uh3R{a/  
{ #f,y&\Xmf  
siteInfoBean = bean; \2v"YVWw  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); nv/[I,nw  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Gh( A%x)  
if(tmpFile.exists ()) t?eH
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{ @%ECj)u`O  
bFirst = false; 83Ou9E!W  
read_nPos(); zGo|JF  
} a2@c%i  
else K7)kS  
{ k;^ :  
nStartPos = new long[bean.getNSplitter()]; \Y|*Nee}XP  
nEndPos = new long[bean.getNSplitter()]; P:xT0gtt  
} hpbf&S4  
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} D
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public void run() *f+: <=i  
{ 5"KlRuv%  
//获得文件长度 ?h8{xa5b  
//分割文件 TLa]O1=Bf.  
//实例FileSplitterFetch o*S"KX$  
//启动FileSplitterFetch线程 X[$++p .
  
//等待子线程返回 >bo'Y9C  
try{ _GYMPq\%L#  
if(bFirst) 2-+f1,  
{ Vm1-C<V9  
nFileLength = getFileSize(); A<MtKb  
if(nFileLength == -1) `)$_YZq|SR  
{ 0#p/A^\#7M  
System.err.println("File Length is not known!"); e]8,:Gd(  
} 2tQ`/!m>v$  
else if(nFileLength == -2) $&I'o  
{ -7qIToO.  
System.err.println("File is not access!"); fz_nsVD  
} <yUstz,Xu^  
else v $({C  
{ V*[b}Xew  
for(int i=0;i<nStartPos.length;i++) afG{lWE)  
{ ~.g3ukt  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); fPa9ofU/kr  
} ?}QH=&=^  
for(int i=0;i<nEndPos.length-1;i++) DvXHK  
{ clO,}Ph>  
nEndPos = nStartPos[i+1]; k+ o|0  
} z_|oCT!6  
nEndPos[nEndPos.length-1] = nFileLength; i'/m4 !>h  
} Rd*[%)  
} oA-:zz>wL  
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//启动子线程 o2H1N~e#c  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; },$0&/>ft  
for(int i=0;i<nStartPos.length;i++) g{k1&|  
{ 7;:#;YSha  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,T,:-E  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), p*QKK@C  
nStartPos,nEndPos,i); <[ Xw)/#  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); A#wEuX=[  
fileSplitterFetch.start(); I3
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} 3INI?y}t  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), xl9aV\
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 7L5P%zLtB  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", {}~:&.D  
nEndPos = " + nFileLength); YvL?j  
// fileSplitterFetch[nPos.length-1].start(); Y$>-%KcKeI  
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//等待子线程结束 W~n.Xeu{C  
//int count = 0; p/6zEZ*  
//是否结束while循环 p zw8T  
boolean breakWhile = false; c
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while(!bStop) f>jwN@(  
{ +|cI:|H>  
write_nPos(); c~}l8M%  
Utility.sleep(500); Tb;d.^  
breakWhile = true; upn~5>uCP  
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for(int i=0;i<nStartPos.length;i++) dhPKHrS  
{
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if(!fileSplitterFetch.bDownOver) w&h2y4  
{ &7mW9]  
breakWhile = false; .1 )RW5|c  
break; I5ss0JSl/  
} ={2!c0s  
} yc;3Id5?>  
if(breakWhile) B:TR2G9UT  
break; e0,'+;*=g  
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//count++; H;ZHqcUX  
//if(count>4) 7
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// siteStop(); R{Z-m2La  
} kK>Xrj6  
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System.err.println("文件下载结束！"); qeL pXe0c  
} Ji'(`9F&a  
catch(Exception e){e.printStackTrace ();} F'PQqb{  
}
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//获得文件长度 zR6siAV9  
public long getFileSize() }3
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{ [onqNp  
int nFileLength = -1; BbOu/i|  
try{ or*HC&c7  
URL url = new URL(siteInfoBean.getSSiteURL()); =v~1qWX  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %
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httpConnection.setRequestProperty("User-Agent","NetFox"); _o6G6e,  
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|
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int responseCode=httpConnection.getResponseCode(); BG`s6aC|z<  
if(responseCode>=400) 0>Z ;Ni  
{ 
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processErrorCode(responseCode); \{\MxXW  
return -2; //-2 represent access is error hn)a@  
} D87|q4  
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String sHeader; q0mOG^  
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for(int i=1;;i++) Ds8 EMtS  
{ sRHA."A!8  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); R0Ue0pF7  
//Utility.log(in.readLine()); zJlQ_U-!  
sHeader=httpConnection.getHeaderFieldKey(i); Yj(4&&Q  
if(sHeader!=null) 7^TV~E#  
{ Iry  
if(sHeader.equals("Content-Length")) 4NR@u
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{ G\gMC <3  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); /?-7Fg+,  
break; 6R UrF  
} u`:
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} Gi6T["  
else XkmQBV"  
break; HjNxqaljt  
} Btt]R
 
} Y
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&{  
catch(IOException e){e.printStackTrace ();} er.L7  
catch(Exception e){e.printStackTrace ();} al9.}  
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Utility.log(nFileLength); Z{NC
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return nFileLength; *!e(A ]&  
} <-Bx&Q  
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//保存下载信息（文件指针位置） i7[uL
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private void write_nPos() `BFIC7a  
{ ~:Uwg+]j  
try{ hPhZUL%  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 6&U+6gb  
output.writeInt(nStartPos.length); ZUXr!v/R:1  
for(int i=0;i<nStartPos.length;i++) #%3rTU  
{ W1aa:hEf  
// output.writeLong(nPos); C.MoKa3  
output.writeLong(fileSplitterFetch.nStartPos); C&\5'[*  
output.writeLong(fileSplitterFetch.nEndPos); >XW
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} $K~LM8_CKy  
output.close(); H(^bC5'  
} $3+PbYY  
catch(IOException e){e.printStackTrace ();} m(OvD!  
catch(Exception e){e.printStackTrace ();}  r}_c  
} 'Yy&G\S  
{ >{B`e`$  
) iQ   
//读取保存的下载信息（文件指针位置） _>o-UBb4]T  
private void read_nPos() w2(guL($  
{ *v%rMU7,  
try{ L *[K>iW  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); w
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int nCount = input.readInt(); =dP{Gh  
nStartPos = new long[nCount]; c>bq%}  
nEndPos = new long[nCount]; Eu<1Bse;  
for(int i=0;i<nStartPos.length;i++) v{x{=
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{ -]G(ms;}/Y  
nStartPos = input.readLong(); (LAXM x  
nEndPos = input.readLong(); 2i#Sn'1  
} `:{B(+6  
input.close(); p^m5`{1]x  
} 0Sl]!PZR1  
catch(IOException e){e.printStackTrace ();} 72TI  
catch(Exception e){e.printStackTrace ();} 3+7^uR$/I4  
} w]j+9-._  
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private void processErrorCode(int nErrorCode) ^>4
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{ w[Gh+L30=5  
System.err.println("Error Code : " + nErrorCode); wYsZM/lw  
} =wu*D5  
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//停止文件下载 <pLT'Y=  
public void siteStop() hm$X]H`uMX  
{ ^{@!['  
bStop = true; U$&hZ_A  
for(int i=0;i<nStartPos.length;i++) iGXI6`F"  
fileSplitterFetch.splitterStop(); `xS{0P{uj  
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} 7J$b$P0}  
} {0\,0*^p  
//负责部分文件的抓取 _,h@:Xij  
**FileSplitterFetch.java =(AtfW^H  
*/ j|.} I  
package NetFox; V)o,1  
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import java.io.*; DLE8+NV8   
import java.net.*; vy@rQC %9  
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public class FileSplitterFetch extends Thread { JYqSL)Ta*t  
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String sURL; //File URL ig"uXs  
long nStartPos; //File Snippet Start Position lw%?z/HDf  
long nEndPos; //File Snippet End Position 8am`6;O:!  
int nThreadID; //Thread's ID e>'H IO  
boolean bDownOver = false; //Downing is over `A%^UCd  
boolean bStop = false; //Stop identical 9e!NOl\_;.  
FileAccessI fileAccessI = null; //File Access interface ye6H*K  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException pz^<\  
{ XP[uF ;w  
this.sURL = sURL; K5Wg"^AHY/  
this.nStartPos = nStart; 1tzV
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this.nEndPos = nEnd; u}hF8eD  
nThreadID = id; ,M !tm7  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 G* %t'jX9  
} wl=61Mb  
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public void run() %u{W7  
{ JD>d\z2QC  
while(nStartPos < nEndPos && !bStop) igf)Hb;5  
{ Ha>*?`?yI  
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try{ &tR(n$M@>  
URL url = new URL(sURL); jPvDFT^d/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); td2/9|Q  
httpConnection.setRequestProperty("User-Agent","NetFox"); @=S}=cl  
String sProperty = "bytes="+nStartPos+"-"; R  
httpConnection.setRequestProperty("RANGE",sProperty); u?ek|%Ok  
Utility.log(sProperty); I&c ~8Dw  
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InputStream input = httpConnection.getInputStream(); ~Z/ ^c,[:  
//logResponseHead(httpConnection); U09.Y  
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byte[] b = new byte[1024]; G%p~m%zIK  
int nRead; wJb#
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 2Tav;LKX  
{ SM0M%  
nStartPos += fileAccessI.write(b,0,nRead); 1B>Vt*=  
//if(nThreadID == 1) Yx'res4e  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); u),Qa=Wp  
} wle@vCmr  
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Utility.log("Thread " + nThreadID + " is over!"); ~%u|[$  
bDownOver = true; $S*4r&8ZD  
//nPos = fileAccessI.write (b,0,nRead); Z!xVgM{  
} UAF<m1  
catch(Exception e){e.printStackTrace ();} $$Vt7"F  
} " }gVAAvc7  
} Nb2Qp K  
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//打印回应的头信息 ylf[/='0K  
public void logResponseHead(HttpURLConnection con) Sgb*tE)T  
{ U7mozHS,:9  
for(int i=1;;i++) PHg48Y"Nd  
{ et,GrL)l  
String header=con.getHeaderFieldKey(i); /e\{   
if(header!=null) ^ OJyN,A  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); t-u|U(n
 
Utility.log(header+" : "+con.getHeaderField(header)); =bh*[,-  
else ~H)4)r^  
break; $v.C0 x  
} nm$Dd~mxW1  
} Thy=yz;p  
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public void splitterStop() R`Aj|C z  
{ wCs3:@UH  
bStop = true; ~cAZB9Fa  
} ub0zJTFJ#  
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} >e5 *p
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/* $$i.O}  
**FileAccess.java .o%^'m"=D[  
*//文件访问(定位，写) 7x]4`#u  
package NetFox; Sydh2d  
import java.io.*; ,7Y-k'7Kop  
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public class FileAccessI implements Serializable{ n6WY&1ZE~  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 LL^q1)o  
RandomAccessFile oSavedFile; P=N$qz
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long nPos; $FH18  
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public FileAccessI() throws IOException A% Q!^d  
{ (9\;A*CZ  
this("",0); 6q<YJ.,  
} yAT^VRbv  
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public FileAccessI(String sName,long nPos) throws IOException os3 8u!3-  
{ CDj~;$[B  
oSavedFile = new RandomAccessFile(sName,"rw"); C#rc@r,F  
this.nPos = nPos; JE5  
oSavedFile.seek(nPos); + Y.1)i}  
} _R|Ify#J  
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\e=_ 2^v!_  
public synchronized int write(byte[] b,int nStart,int nLen) pD"vRbYF  
{ f8 /'%$N  
int n = -1; i>L+gLW  
try{ Uk*IpP`  
oSavedFile.write(b,nStart,nLen); pY)5bSA  
n = nLen; M`,~ mU  
} U=Y)V%  
catch(IOException e) 1[F3 Z  
{ sRVIH A,  
e.printStackTrace (); C-eA8pYY/  
} -Ue$T{;RoH  
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return n; =rA~7+}  
} /gcEw!JS  
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} [sV"ws  
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/* ~\p]~qQ\K  
**SiteInfoBean.java MiT}L  
*/ v dbO(  
package NetFox; `J<*9dq%  
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public class SiteInfoBean { 7`vEe'qz  
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private String sSiteURL; //Site's URL UsGa  
private String sFilePath; //Saved File's Path 5wB =>  
private String sFileName; //Saved File's Name [L`ZE*z  
private int nSplitter; //Count of Splited Downloading File 0C<[9Dl.G8  
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7qOa ;^T  
public SiteInfoBean() 6%`&+Lq  
{//nSplitter的缺省值为5 'C$XS>S  
//default value of nSplitter is 5 #1c]PX  
this("","","",5); vr#+0:|  
} @Q&3L~K"  
I +5)Jau^S  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) I&?Qq k  
{ Xdi:1wW@p  
sSiteURL= sURL; ;Mm7n12z C  
sFilePath = sPath; 7A\Cbu2tf  
sFileName = sName; 7g=2Z[o  
this.nSplitter = nSpiltter; k$5 s{q  
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} ZN
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public String getSSiteURL() r
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{ ?1L
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return sSiteURL;  [=O/1T  
} )}Q(Tl\$  
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=U[3PC-N@  
public void setSSiteURL(String value) HS'Vi9  
{ Er/bO  
sSiteURL = value; Ze<K=Q%(i  
} UT~a&u  
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s &Dg8$  
public String getSFilePath() W{z.?$SH  
{ G6V
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return sFilePath; }(a+aHH  
} O/:UJ( e{  
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public void setSFilePath(String value) 4tg<iH
{  
{ XxHx:
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sFilePath = value; w6`9fX6{h  
} 5tQ1fJze  
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public String getSFileName() )
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{ 'c\iK
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return sFileName; I%|>2}-_U  
}  zYXV;  
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public void setSFileName(String value) 1+b{}d  
{ ' |-JWH  
sFileName = value; e\O/H<  
} '=][J_
 
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public int getNSplitter() Pxn,Qw*  
{ 1[_mEtM:]B  
return nSplitter; w
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} oJ#
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$R<Me  
public void setNSplitter(int nCount) nRd)++  
{ I ZQHu h  
nSplitter = nCount; l & D
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} t|t#vcB  
} kd"N29  
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/* ,C3,TkA]  
**Utility.java }kg ye2[  
*/ u!1{Vt87  
package NetFox; 4k./(f2+  
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public class Utility { =4d (b ;  
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public Utility() Y8flrM2CwG  
{ 5zON}"EC  
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} %`Z!4L  
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//线程睡眠 (sWLhUgRX  
public static void sleep(int nSecond) phO;c;
y}  
{ E*i#?u  
try{ _X?^Cy  
Thread.sleep(nSecond); ctcS:<r/3@  
} V|\7')Qq  
catch(Exception e) qZ@s#UiB  
{ e%W$*f  
e.printStackTrace (); yCCrK@{oo  
} r(gXoq_w  
} !?Wp+e6  
}@.|?2b +  
//日志 !A48TgAeE  
public static void log(String sMsg) ]qhPd_$?D'  
{ ~/j\Z  
System.err.println(sMsg); 7gRgOzWfV  
} #Fyuf,hw4  
LR"9D
 
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public static void log(int sMsg) S*yjee<@  
{ BT}&Y6  
System.err.println(sMsg); qWw\_S  
} $AHQmyg<  
} EqI(|bFwy  
=-p$jXVW%  
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/* J4Dry<  
**TestMethod.java Mw9 \EhA  
*/ [` sL?&a  
package NetFox; #:SNHM^><  
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public class TestMethod { 1^gl}^|B  
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public TestMethod() 2;w*oop,O  
{ ///xx/weblogic60b2_win.exe 5h;+Ky!I  
try{ ~Jf{4*>y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); k1Q?'<`  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); j&k6O1_  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 0Fu~
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fileFetch.start(); 4>J   
} y+7PwBo%e  
catch(Exception e){e.printStackTrace ();} '(/7[tJ  
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} <_
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public static void main(String[] args) }l=xiAF  
{ T1H"\+  
new TestMethod(); fDSv?crv  
}
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}
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