http断点续传简单实现（java)

/* rL.<Z@-  
**SiteFileFetch.java uT'-B7N  
*/ Zm`'MsgFr  
package NetFox; :QxL 9&"  
import java.io.*; +p8qsT#7  
import java.net.*; T-hU+(+hg  
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public class SiteFileFetch extends Thread { H-;&xzAI  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Xs{:[vRW  
long[] nStartPos; //开始位置 =W;
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long[] nEndPos; //结束位置 k, $I59  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 4!NfQk>X  
long nFileLength; //文件长度 Y]D7i?3N  
boolean bFirst = true; //是否第一次取文件 3D]2$a_d  
boolean bStop = false; //停止标志 Mp]yKl  
File tmpFile; //文件下载的临时信息 4jDs0Hn"  
DataOutputStream output; //输出到文件的输出流
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N
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） L*kh?PS;  
public SiteFileFetch(SiteInfoBean bean) throws IOException 1}i&HIr!b  
{ ;,Of\Efc|  
siteInfoBean = bean; 5HWwl.
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); fF8a 1XV  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ?7fQ1/emhO  
if(tmpFile.exists ()) <O <'1uO,  
{ 6ctHL<^  
bFirst = false; a7XXhsZ  
read_nPos(); Xtu:  
} _)HD4,`  
else B"pFJ"XR  
{ I}6
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nStartPos = new long[bean.getNSplitter()]; |V5$'/Y  
nEndPos = new long[bean.getNSplitter()];

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} 2P;%P]~H  
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} ak~=[
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public void run()

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{ VEFwqB1l  
//获得文件长度 *"|VNnB  
//分割文件 Q0 uP8I}n  
//实例FileSplitterFetch 5Z4(J?n  
//启动FileSplitterFetch线程 icKg7-$N  
//等待子线程返回 ]7XkijNb  
try{ lpM>}0v   
if(bFirst) 2<46jJYL'  
{ >!HfH(is\  
nFileLength = getFileSize(); 3s+<  
 
if(nFileLength == -1) ~8KF<2c   
{ i6!T`Kau  
System.err.println("File Length is not known!"); Sleu#]-  
} p=mCK@  
else if(nFileLength == -2) v!pj v%  
{ l|R
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System.err.println("File is not access!"); N$=(1`zM=  
} ;~'cITL  
else 7G<KrKal  
{ I]uOMWZs  
for(int i=0;i<nStartPos.length;i++) (<d&B
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{ 'S%} ?#J  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); [*Aqy76Qa  
} Yj^avO=;  
for(int i=0;i<nEndPos.length-1;i++) 1sIy*z  
{ QK``tWLIg7  
nEndPos = nStartPos[i+1]; L5-T6CD  
} LK  
nEndPos[nEndPos.length-1] = nFileLength; ei+
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} Tc'{i#%9j  
} #f|NM7  
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//启动子线程 hX>VVeIZ  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ${E[pT  
for(int i=0;i<nStartPos.length;i++) 6oTbn{=UUq  
{ %h/#^esi  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Q+u#?['  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), k *G!.  
nStartPos,nEndPos,i); ]2aYi9)  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ZuFVtW@  
fileSplitterFetch.start(); g "K#&  
} #Vn>ue+?  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Kc2OLz#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); QKUBh-QFK  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 6h0U  
nEndPos = " + nFileLength); 9rpg10/T  
// fileSplitterFetch[nPos.length-1].start(); He0N  

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7 BnenHD  
//等待子线程结束 <y\
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//int count = 0; Y?&DEKFbD  
//是否结束while循环 &0th1-OP_  
boolean breakWhile = false; sw=JUfAhy  
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while(!bStop) "&~?Hzm  
{ 5Sm5jRr  
write_nPos(); Tjeo*n^  
Utility.sleep(500); B:6sVJ  
breakWhile = true; I
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for(int i=0;i<nStartPos.length;i++) 4B3irHs\Q  
{ >^a"Z[s[  
if(!fileSplitterFetch.bDownOver) bD-/ZZz  
{ TsFdy{/o*  
breakWhile = false; ['}^;Y?*o  
break; qUoMg%Z%l  
} V&4:nIS>z  
} Kl46CZs#8  
if(breakWhile) HM$`z"p5jg  
break; MWn L#!  
mSk :7ozZ  
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//count++; aG8D%i0  
//if(count>4) q563,s  
// siteStop(); &JXHDpd$a^  
} U>p
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System.err.println("文件下载结束！"); m`yn9(1Y[  
} 5|~r{w)9  
catch(Exception e){e.printStackTrace ();} CyK$XDHa  
} @7HOL-i  
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//获得文件长度 \9|]  
public long getFileSize() {Hp}F!X$  
{ $*v20  
int nFileLength = -1; !6tC[W`  
try{ ?CT^Zegmr  
URL url = new URL(siteInfoBean.getSSiteURL()); PkCeV]`w  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Zs5I?R1e8  
httpConnection.setRequestProperty("User-Agent","NetFox"); C
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int responseCode=httpConnection.getResponseCode(); ^;k _  
if(responseCode>=400) l5y#i7q  
{ _#YHc[Wz  
processErrorCode(responseCode); {DXZ}7w:v  
return -2; //-2 represent access is error yu?
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} >NOYa3  
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String sHeader; Q@ )rw0$  
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for(int i=1;;i++) *liPJ29C[  
{ 0h@%q;g  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 0)`lx9&h  
//Utility.log(in.readLine()); #HnyE+tD  
sHeader=httpConnection.getHeaderFieldKey(i); zIQc#F6\5  
if(sHeader!=null) im?XXsH'  
{ Bc|x:#`C\{  
if(sHeader.equals("Content-Length")) :56lzsWUE<  
{ 6pn@`UK  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); N;ecT@Ug  
break; <<2b2?aS`  
} {!g.255+  
} V\M!]Nnxr  
else 'y M:WcN  
break; ^Lfn3.M  
} U_{JM`JY  
} CU>K  
catch(IOException e){e.printStackTrace ();} U)w|GrxX  
catch(Exception e){e.printStackTrace ();} 5G]#yb74  

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Utility.log(nFileLength); K!: ,l  
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return nFileLength; 8rG&CxI  
} ?jn6Op  
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//保存下载信息（文件指针位置） 7}1Kafs  
private void write_nPos() +heS\I_Mp  
{ ])wMUJWg2  
try{ /qq&'}TZP  
output = new DataOutputStream(new FileOutputStream(tmpFile)); j5Wx*~@(  
output.writeInt(nStartPos.length); YlcF-
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for(int i=0;i<nStartPos.length;i++) v3JIUdU=P  
{ ^57fHl
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// output.writeLong(nPos); cKYvRe  
output.writeLong(fileSplitterFetch.nStartPos); L{0OMyUA  
output.writeLong(fileSplitterFetch.nEndPos); S5 nw  
} A-wxf91+:  
output.close(); OI}HvgV^!  
} MW[ 4^  
catch(IOException e){e.printStackTrace ();} yoY)6cn@  
catch(Exception e){e.printStackTrace ();} DF
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} W>|b98NPu  
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//读取保存的下载信息（文件指针位置） >T*g'954xF  
private void read_nPos() x[>_I1TJ  
{ k`~br249  
try{ boOw K?  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Q fyERa\rb  
int nCount = input.readInt(); c3!|h1h/v  
nStartPos = new long[nCount]; ^$,kTU'=  
nEndPos = new long[nCount]; pH:|G  
for(int i=0;i<nStartPos.length;i++) &?`&X=Q  
{ qf=[*ZY  
nStartPos = input.readLong(); pVa|o&,  
nEndPos = input.readLong(); 8Bt-  
} fh)`kZDk  
input.close(); x-#9i  
} Mh.eAM8_  
catch(IOException e){e.printStackTrace ();} #DRtMrfat  
catch(Exception e){e.printStackTrace ();} -*q2Y^A^l  
} K':pU1  
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private void processErrorCode(int nErrorCode) wX
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{ KC-aLq/  
System.err.println("Error Code : " + nErrorCode); _vLT!y  
} WI!z92qq[  
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//停止文件下载 Tc(v\|F,  
public void siteStop() r=||sZs  
{ BBJ]>lQ  
bStop = true; :::f,aCAu  
for(int i=0;i<nStartPos.length;i++) +\oHQ=s>}\  
fileSplitterFetch.splitterStop(); molowPI  
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} ![!b^:f  
} *g41"Cl  
//负责部分文件的抓取 L0V

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**FileSplitterFetch.java ?HyioLO  
*/ 2^ZPO4|  
package NetFox; 'htA! KHF  
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import java.io.*; *K.7Zf0  
import java.net.*;
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public class FileSplitterFetch extends Thread { S|4/C  
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String sURL; //File URL |M>k &p,B-  
long nStartPos; //File Snippet Start Position 4H?Ma|,  
long nEndPos; //File Snippet End Position W}_}<rlF  
int nThreadID; //Thread's ID HU+H0S~g  
boolean bDownOver = false; //Downing is over _rJSkZO  
boolean bStop = false; //Stop identical )tch>.EQ_  
FileAccessI fileAccessI = null; //File Access interface 0i`Zy!  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException
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{ 1O7ss_E  
this.sURL = sURL; 2^M+s\p  
this.nStartPos = nStart; ^ED>{UiNI  
this.nEndPos = nEnd; jtr=8OiL  
nThreadID = id; h1o+7  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 h#ot)m|I  
}  Ph{+uI  
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public void run() V\hct$ 7Vm  
{ 13kb~'+&r  
while(nStartPos < nEndPos && !bStop) z))[Lg  
{ 7uNI  
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try{ @}!$NI8  
URL url = new URL(sURL); w>Sz^_ h  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ( +hI
  
httpConnection.setRequestProperty("User-Agent","NetFox"); :8wF0n-'  
String sProperty = "bytes="+nStartPos+"-"; !`=?<Fl  
httpConnection.setRequestProperty("RANGE",sProperty); 6e|5qKr  
Utility.log(sProperty); Z[bC@y[Wb  
}0>/G?2Yp  
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InputStream input = httpConnection.getInputStream(); X}Z%@tL  
//logResponseHead(httpConnection); .Q)"F /  
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byte[] b = new byte[1024]; @+#p:sE  
int nRead; .WE0T|qDX  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ;_&L^)~P$  
{ bQjHQ"
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nStartPos += fileAccessI.write(b,0,nRead); 3*JybMo"  
//if(nThreadID == 1) >G~;2K[  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1&"1pH  
} 0^Cx`xdX:  
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Utility.log("Thread " + nThreadID + " is over!"); Sxu v}y\  
bDownOver = true; S]g)^f'a65  
//nPos = fileAccessI.write (b,0,nRead); liP{Mu/LO  
} e,UgTxZ  
catch(Exception e){e.printStackTrace ();} q~_jF$9SX  
} i=QhXCM  
} iUBni&B  
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//打印回应的头信息 9ksrr{tW  
public void logResponseHead(HttpURLConnection con) lM,:c.R  
{ x&Rp m<4  
for(int i=1;;i++)  N&.p\T&t  
{ TaT&x_v^~a  
String header=con.getHeaderFieldKey(i); %TgM-F,8  
if(header!=null) 9Bw"VN]W  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); _Z2)e*(  
Utility.log(header+" : "+con.getHeaderField(header)); ?3N86Qj  
else Sn&%epi  
break; Y|nTc.A  
} eqCB2u"Jq  
} R"([Y#>m  
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public void splitterStop() Bx>@HU
 
{ Z U
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bStop = true; So`"z[5  
} R&xd ic!  
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} L 3@wdC~0  
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/* 4*X$Jle|  
**FileAccess.java 92Iv'(1ba  
*//文件访问(定位，写) `,[c??h  
package NetFox; 5GkM7Zu!{j  
import java.io.*; kGP?Jx\PkH  
6suc:rp";  
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public class FileAccessI implements Serializable{ W0kq>s4  
?]N&H90^5  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Q-5wI$=  
RandomAccessFile oSavedFile; b
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long nPos; e: tp7w 4  
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public FileAccessI() throws IOException N0C5FSH  
{ rC16?RovQ@  
this("",0); -X \vB  
} 7F\g3^z9`  
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public FileAccessI(String sName,long nPos) throws IOException zu%pr95U  
{ ta(x
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oSavedFile = new RandomAccessFile(sName,"rw"); p4 PFoFo2  
this.nPos = nPos; dD%m=x  
oSavedFile.seek(nPos); 6}$cDk`dz  
} >2/zL.O  
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public synchronized int write(byte[] b,int nStart,int nLen) *TkABUL  
{ NQ!F`  
int n = -1; u 36;;z  
try{ S\m]ze  
oSavedFile.write(b,nStart,nLen); D=Y HJ>-wB  
n = nLen; =@>&kU%$&  
} w?q"%F;/  
catch(IOException e) PYe>`X?  
{ v*LL7b0A  
e.printStackTrace (); J:a^''  
} QR)eJ5<  
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return n; , +^db)  
} x!+a,+G  
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} jg(A_V  
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/* XQA2uR4h  
**SiteInfoBean.java SEmD's  
*/ y(A"g3^=  
package NetFox; bOdD:=f  
%O${EN  
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public class SiteInfoBean { mfvQ]tz_+  
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private String sSiteURL; //Site's URL eu=2a>  
private String sFilePath; //Saved File's Path 'e@}N)IX  
private String sFileName; //Saved File's Name 'Vd>"ti  
private int nSplitter; //Count of Splited Downloading File ?)&TewP  
vKe
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public SiteInfoBean() 21qhlkdc  
{//nSplitter的缺省值为5 92i#It}-/  
//default value of nSplitter is 5 {`LV{!  
this("","","",5); ]+8,@%="  
} @h]H_  
+j,;g#d  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) nL?B  
{ q3:tZoeXV  
sSiteURL= sURL; !`g
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sFilePath = sPath; ` T!O )5  
sFileName = sName; ^RyrUb  
this.nSplitter = nSpiltter; ,x/j&S9!  
"'Q:%_;  
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} @."R9s  
/%)J+K)  
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public String getSSiteURL() xM:dFS  
{ .1@5*xQ5O  
return sSiteURL; Z&%61jGK  
} 3-05y!vbcE  
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public void setSSiteURL(String value) >nxtQ  
{ 8Y9mB#X  
sSiteURL = value; 7"NUof?i  
} 7j Q`i;L}Y  
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public String getSFilePath() }Y[.h=X  
{ 6=
 
return sFilePath; Q|>y2g!  
} D"MNlm  
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public void setSFilePath(String value) eR/7*G5  
{ ^%L$$V nG  
sFilePath = value; 3eB2=_V`  
} (8I0%n}.Zo  
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public String getSFileName() 0V^?~ex  
{ #E#70vWp\O  
return sFileName; B 5?(gb"  
} ]OVjq?  
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public void setSFileName(String value) $j:0*Z=>  
{ 4l|Am3vzX  
sFileName = value; mp#5Vc  
} . &e,8  
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public int getNSplitter() [L8gG.wy  
{ 3laSPih[.  
return nSplitter; PtHT>  
} 7(jt:V6V  
8S0)_L#S  
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public void setNSplitter(int nCount) K46\Rm_:B;  
{ g$<@!  
nSplitter = nCount; R}0cO^V  
} %spR7J\"/  
} /XXW4_>  
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/* htjJ0>
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**Utility.java |h#mv~cF  
*/ znM"P|A  
package NetFox; S\C   
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public class Utility { B *:6U+I  
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public Utility() Q>.-u6(&  
{ Y4i-Pp?  
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} #i~.wQ$1  
)wKuumet  
//线程睡眠 TPkm~>zD.  
public static void sleep(int nSecond)
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{ 
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try{ ^,?]]=mE  
Thread.sleep(nSecond); [P[syi#]t  
} +%FGti$[  
catch(Exception e) lVqvS/_k$  
{ sl)_HA7G  
e.printStackTrace (); MOj 0"x)  
} Gm*i='f!?  
} sI~{it#  
HMBxj($eR  
//日志 r+) A)a,  
public static void log(String sMsg) 6OVAsmE  
{ $ @^n3ZQ4  
System.err.println(sMsg); %DiZ&}^Ck  
} %N!Y}$y  
iJq}tIk#2'  
#fa~^]EM]  
public static void log(int sMsg) vHao y  
{ 50CU|  
System.err.println(sMsg); N?~K9jGx(  
} ?4xTA  
} NxNz(R $~  
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~_R=2t{u_  
/*  |,.glL  
**TestMethod.java {4#'`Eejj  
*/ cP(/+ /9  
package NetFox; "5vFa7y  
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public class TestMethod { |,qz7dpe  
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public TestMethod() Z,ag5 w`]L  
{ ///xx/weblogic60b2_win.exe C,K
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try{ Zr`:A$  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); +f|u5c  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); +`\C_i-  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 8on2BC2  
fileFetch.start(); Vk[m$  
} 3EAu#c@q"  
catch(Exception e){e.printStackTrace ();} `57ffQR9  
Dtelr=/s  
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} [t,7H  
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public static void main(String[] args) aWW|.#L  
{ rlW
  
new TestMethod(); )V+;7j<"D  
} ]_j{b
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} j5tA!o  
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