http断点续传简单实现（java)

/* Q G=-LXv:@  
**SiteFileFetch.java T@d_t  
*/ $v?
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package NetFox; ,J`lr U0  
import java.io.*; @4 Os?_gJ\  
import java.net.*; -N-4l  
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public class SiteFileFetch extends Thread { aOAwezfYR  
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SiteInfoBean siteInfoBean = null; //文件信息Bean HwVgT"  
long[] nStartPos; //开始位置 (DELxE  
long[] nEndPos; //结束位置 }v'PY/d.  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 a@S4IoBg%  
long nFileLength; //文件长度 #(26t _a  
boolean bFirst = true; //是否第一次取文件 ?hry=I(7r  
boolean bStop = false; //停止标志 k^'d@1z;C  
File tmpFile; //文件下载的临时信息 gN!E*@7  
DataOutputStream output; //输出到文件的输出流 +hyWo]nW0  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） .JD4gF2N  
public SiteFileFetch(SiteInfoBean bean) throws IOException 0T{c:m~QXe  
{ {'=Nb 5F  
siteInfoBean = bean; pd
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); CL<KBmW7  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ,XBV}y  
if(tmpFile.exists ()) Dbkuh!R  
{ sBuq  
bFirst = false; SG+i\yu$h0  
read_nPos(); 2=!3[> B  
} 0c\|S>g[  
else 6ljRV)  
{ ELkOrV~a{:  
nStartPos = new long[bean.getNSplitter()]; qqz,~EhC  
nEndPos = new long[bean.getNSplitter()]; `1[Sv"  
} sJHy=z0m  
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} iEJQ#5))0  
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}
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public void run() oZ*=7u  
{ ffoo^1}1  
//获得文件长度 }Nd`;d  
//分割文件 Q 2SSJ  
//实例FileSplitterFetch S'%cf7Z  
//启动FileSplitterFetch线程 [ilv/V<  
//等待子线程返回 Z.Y;[Y  
try{ "ZJ1`R=Mj  
if(bFirst) WT ~dA95  
{ (-Ct!aW|  
nFileLength = getFileSize(); L9unhx  
if(nFileLength == -1) K+\0}qn  
{ K^cWj_a"  
System.err.println("File Length is not known!"); EfrkB"  
} hO<w]jV,  
else if(nFileLength == -2) meM.?kk(  
{ |>/&EElD  
System.err.println("File is not access!"); /Y\E68_Fh  
} s?Qb{  
else c[d'1=Qiy  
{ sWZtbW;)  
for(int i=0;i<nStartPos.length;i++) nGJIjo_I  
{ :86luLFm  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); l"pz )$eE  
} (h@yA8>n  
for(int i=0;i<nEndPos.length-1;i++) >s 8:1l  
{ j2{,1hj  
nEndPos = nStartPos[i+1]; l]klV+9t  
} Bg+]_:<U  
nEndPos[nEndPos.length-1] = nFileLength; s=%+o&B  
} @|UIV  
} k.%W8C<Pa  
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//启动子线程 "/K&qj  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length];
#NQz&4W  
for(int i=0;i<nStartPos.length;i++) 6<Pg>Bg  
{ + x;ML  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), gq:TUvX  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), i>if93mpj  
nStartPos,nEndPos,i); I.\f0I'.  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 2}#wdJ`  
fileSplitterFetch.start(); feq6!k7  
} kx:lk+Tx  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Q"K>ML>0  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); A7,$y!D  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 2p;}wYt  
nEndPos = " + nFileLength); n.qxxzEN  
// fileSplitterFetch[nPos.length-1].start(); Sp$x%p0  
/%q9hI  
Nj@?}`C 4  
//等待子线程结束 \F+o
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//int count = 0; >LaL!PnZ  
//是否结束while循环 1q233QSW)  
boolean breakWhile = false; wyA(}iSq  
~G^}2#5  
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while(!bStop) d_7Xlp@  
{ gjN!_^_  
write_nPos(); .]ZuG  
Utility.sleep(500); acju!,G  
breakWhile = true; =UKR<@QrK  
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for(int i=0;i<nStartPos.length;i++) SnF[mN'  
{ _Il9s#NA%  
if(!fileSplitterFetch.bDownOver) 6r-n6#=  
{ 3w:Z
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breakWhile = false; jUR#  
break; |e[0Qo@  
} xjbyI_D  
} llG#nDe  
if(breakWhile) _}9R}  
break; >=W#z  
*=I
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sriq(A  
//count++; nh&<fnh  
//if(count>4) .rB;zA;4S)  
// siteStop(); n ua8y(W  
} &MQt2aL  
*u4X<oBS*  
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System.err.println("文件下载结束！"); ~$ qJw?r  
} |>}0? '/]  
catch(Exception e){e.printStackTrace ();} WKJL< D ]:  
} }nY^T&?`  
KJJb^6P48W  
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//获得文件长度 WAmoKZw2  
public long getFileSize() ?G>TaTiK#  
{ #bZ
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int nFileLength = -1; w~KBk)!*  
try{ +e4<z%1  
URL url = new URL(siteInfoBean.getSSiteURL()); CU`Oc>;*T  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); u`Qcw|R+  
httpConnection.setRequestProperty("User-Agent","NetFox"); pfQZ|*>lkb  
*|#JFy?c[  
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int responseCode=httpConnection.getResponseCode(); /Vd#q)b%T  
if(responseCode>=400) 1Da [!^u,D  
{ _xL&sy09t  
processErrorCode(responseCode); -+_
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return -2; //-2 represent access is error -Fc#  
} Z#:@M[HH{  
2CgIY89O  
6')SJ*|yS  
String sHeader; @>nk^l  
+U)|&1oa  
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for(int i=1;;i++) cBF%])!  
{ @#Uiy5N  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); I_I;.Ik  
//Utility.log(in.readLine()); WCl;#=  
sHeader=httpConnection.getHeaderFieldKey(i); o
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if(sHeader!=null) aq\TO?  
{ @wg
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if(sHeader.equals("Content-Length")) AG\852`1m  
{ }ZVv  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); C^=gZ 6m  
break; & O\!!1%  
} 0@x$Cp  
} y$9t!cx  
else 4x?u5L 9o  
break; 9.#R?YP$  
} >8;%F<o2  
} d4h(F,K7V  
catch(IOException e){e.printStackTrace ();} )[X!/KR90  
catch(Exception e){e.printStackTrace ();} )bU")  
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Utility.log(nFileLength); /D]r

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return nFileLength; $hp?5KM  
} (IHBib "  
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!;C(p
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//保存下载信息（文件指针位置） cE>/iZc  
private void write_nPos() ;p!hd}C  
{ )mVYqlU"  
try{ X&oy.Roo  
output = new DataOutputStream(new FileOutputStream(tmpFile)); -vfu0XI~  
output.writeInt(nStartPos.length); f_2^PF>?  
for(int i=0;i<nStartPos.length;i++) 5nqdY*  
{ PlRs-%d  
// output.writeLong(nPos); Sz@?%PnU|  
output.writeLong(fileSplitterFetch.nStartPos); 2#M:JgWV  
output.writeLong(fileSplitterFetch.nEndPos); }gRLW2&mR>  
} f8jz49C  
output.close(); L(P:n-
^  
} 3v+}YT{>b  
catch(IOException e){e.printStackTrace ();} G6mM6(Sr  
catch(Exception e){e.printStackTrace ();} 2MzFSmhc"  
} PH!B /D5G  
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*t9qH  
//读取保存的下载信息（文件指针位置） vm}.gQ  
private void read_nPos() 1V$B^/_  
{ -"9)c^KVx  
try{ ']e4!  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Xtnmh)'K~#  
int nCount = input.readInt(); :?6$}GcW  
nStartPos = new long[nCount]; v+o3r]Y6  
nEndPos = new long[nCount]; bJ!f,a'/  
for(int i=0;i<nStartPos.length;i++) {:OVBX  
{ [7w_.(f#  
nStartPos = input.readLong(); &YP>"<  
nEndPos = input.readLong(); k\Tm?^L)  
} `9{C/qB  
input.close(); sc>)X{eb  
} u`,R0=<
4  
catch(IOException e){e.printStackTrace ();} A_U0HVx_  
catch(Exception e){e.printStackTrace ();} K
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} Bin&:%|9?  
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private void processErrorCode(int nErrorCode) R:x04!}  
{ c}s3c >`d  
System.err.println("Error Code : " + nErrorCode); |sM#g1D@  
} [N+ruc?)  

* xXc$T  
2;r^~:  
//停止文件下载 urjp&L&  
public void siteStop() &Sp:?I-  
{ LOkDx2@g  
bStop = true; LgKEg90w(  
for(int i=0;i<nStartPos.length;i++) R!xc$`N  
fileSplitterFetch.splitterStop(); 4>`w9  
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} Q 5TyS8  
} :u93yH6~8  
//负责部分文件的抓取 0LuY"(LR  
**FileSplitterFetch.java &`W,'qD$  
*/ V t
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package NetFox; >m{-&1Tx  
vA~hkkj{  
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import java.io.*; o%Q2.  
import java.net.*; Ll48)P{+}V  
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public class FileSplitterFetch extends Thread { )dDmq  
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String sURL; //File URL ,W;8!n0  
long nStartPos; //File Snippet Start Position WLFzLW=PD  
long nEndPos; //File Snippet End Position XaSl6CH  
int nThreadID; //Thread's ID >pHvBFa3G  
boolean bDownOver = false; //Downing is over 3e1"5~?'<  
boolean bStop = false; //Stop identical o62gLO]z@  
FileAccessI fileAccessI = null; //File Access interface e{S`iO  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException &_gmQ;%t:  
{ G&Sg.<hn  
this.sURL = sURL; =5F49  
this.nStartPos = nStart; `XY[HK  
this.nEndPos = nEnd; ]TN}`]  
nThreadID = id; >.>5%  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 |9M y>8k(  
} K?WqA
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public void run() 0Z(b/fdS  
{ <{j
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while(nStartPos < nEndPos && !bStop) 2Z|kf9  
{ Xu0*sQK  
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try{ '(*D3ysU  
URL url = new URL(sURL); a[De  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ><^@
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httpConnection.setRequestProperty("User-Agent","NetFox"); ](pD<FfS]'  
String sProperty = "bytes="+nStartPos+"-"; d~%Rnic6*  
httpConnection.setRequestProperty("RANGE",sProperty); >dY"B$A>  
Utility.log(sProperty); ~46ed3eGzi  
|R;=P(0it  
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InputStream input = httpConnection.getInputStream(); CPG %*E*  
//logResponseHead(httpConnection); 4mg&H0 !  
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byte[] b = new byte[1024]; hBw~l?G  
int nRead; wAYc)u#  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) F9" K  
{ *']RYu?X  
nStartPos += fileAccessI.write(b,0,nRead); 7[\B{N9&W  
//if(nThreadID == 1) AF}HS8
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); )Ec;krb+  
} <rI~+J]s  
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Utility.log("Thread " + nThreadID + " is over!"); {3>^nMv@e  
bDownOver = true; vPi+8)  
//nPos = fileAccessI.write (b,0,nRead); l=yO]a\QZ  
} a@./e @
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catch(Exception e){e.printStackTrace ();} 7E'C o|  
} O%I'  
} =9M-N?cV  
5P4>xv[  
n8Fi?/  
//打印回应的头信息 )yk LUse+  
public void logResponseHead(HttpURLConnection con) 6Jm4?ex  
{ >=bO@)[  
for(int i=1;;i++) 1<F/boF~  
{ T&%>/7I>  
String header=con.getHeaderFieldKey(i); ]pt @  
if(header!=null) k&2I(2S  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); sXUM,h8$!+  
Utility.log(header+" : "+con.getHeaderField(header)); 'D bHXS7N  
else T-MLW=Vu  
break; 7@`(DU`z  
} VybiuP  
} Msf yIB  
rRMC<.=  
~I'hiV^-  
public void splitterStop() _%x|,vo`(  
{ Y#G '[N>  
bStop = true; C$_H)I  
} @!-= :<h  

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} L6FUC6x"  
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*{ .u\BL5  
/* hZy"@y3Yq  
**FileAccess.java l4; LV7Ji  
*//文件访问(定位，写) %n( s;/_  
package NetFox; jE{z4en  
import java.io.*; q>Y_I<
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public class FileAccessI implements Serializable{ u5lj+
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6>l-jTM  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 |YH1q1l  
RandomAccessFile oSavedFile; tW,<Pe  
long nPos; TGg*(6'z  
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public FileAccessI() throws IOException l|DOsI'r  
{ cu Nwv(P  
this("",0); "k+QDQ3=  
} P)T:6K  
Dv$xP)./  

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public FileAccessI(String sName,long nPos) throws IOException %j=7e@  
{ _onHe"%
{  
oSavedFile = new RandomAccessFile(sName,"rw"); ALFw[1X  
this.nPos = nPos; <#c2Hg%jh  
oSavedFile.seek(nPos); 0^;{b^!(  
} S"lcePN  
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h#  
i
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public synchronized int write(byte[] b,int nStart,int nLen) 1@/+ c  
{ 0-=QQOART\  
int n = -1; 2WKA] l;  
try{ Tux~4W  
oSavedFile.write(b,nStart,nLen); /({5x[  
n = nLen; VRD2e ,K  
} Blu^\:?#z-  
catch(IOException e) JAgec`T%  
{ |u03~L9G  
e.printStackTrace (); _yU e2Gd  
} l9n8v\8,o  
rt"\\sOlMB  
,O2Uj3"  
return n; K\ZKVn
  
} .[~E}O  
^b&aDm~(7  
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} Z";o{@p  
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A M# '(k(  
/* ZM<1;!i  
**SiteInfoBean.java _wm"v19  
*/ ak<?Eu9rV  
package NetFox;  }UX>O  
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public class SiteInfoBean { 4H{L>e  
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private String sSiteURL; //Site's URL 7n%QP  
private String sFilePath; //Saved File's Path anv_I=  
private String sFileName; //Saved File's Name j'~xe3j  
private int nSplitter; //Count of Splited Downloading File N-lXC"{)  
)5bhyzSZI  
([s2F%S`@  
public SiteInfoBean() ?"J5~_U
.  
{//nSplitter的缺省值为5 +i{&"o4}  
//default value of nSplitter is 5 BoFJ8Ukq|  
this("","","",5); ^lbOv}C*  
} *S*;rLH9c  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 5'.j+{"  
{ Zb3E-'
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sSiteURL= sURL; Ktg6*L/  
sFilePath = sPath; 3xbA]u;gp  
sFileName = sName;  gryC#  
this.nSplitter = nSpiltter; 9CW .xX8  
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} Z-Zox-I1}-  
!c'a<{d@  
<{:$]3  
public String getSSiteURL() d8e6}
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{ "m(HQ5e)*  
return sSiteURL; rC$ckug  
} 7hY~  
?tg(X[h{S  
V;Te =
4  
public void setSSiteURL(String value) P
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{ D'c,z[  
sSiteURL = value; n:x6bPal]  
} Em%"]B  
<Hig,(=`.  
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public String getSFilePath() 3I@j=:(%Y  
{ ku&IVr%  
return sFilePath; 1s"6  
} 5W(G~m?jC6  
Xq` '^)  
$x)C_WZj?  
public void setSFilePath(String value) Yx>=(B  
{ ej4xW~_  
sFilePath = value; z%<Z#5_N  
} Kp!sn,:  
ZEiW\ V  
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public String getSFileName() 5~5d%C^3k  
{ ^0Cr-  
return sFileName; CuR.a  
} NnRR"'  
[yF>W$Bn%  
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public void setSFileName(String value) gf$5pp-  
{ }`FC'!(   
sFileName = value; xPl+ rsU  
} sG!SSRL@  
*fQ$s  
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public int getNSplitter() HN9!~G  
{ X"0n*UTF,  
return nSplitter; qv>?xKSm  
} h&|q>M3  
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=87.6Ai  
public void setNSplitter(int nCount) '85@U`e.  
{ xXp$Nm]:  
nSplitter = nCount; 35|F?J
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} PQ9.aJdw@-  
} $iu{u|VSu  
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/* 5v<X-8"  
**Utility.java 'mx_]b^O  
*/ J\VG/)E  
package NetFox; |E/U(VS3l~  
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public class Utility { ig(dGKD\=9  
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public Utility() R-CFF  
{ "N\>v#>C  
}A
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} o_C j
o  
t F^|,9_<  
//线程睡眠 eJD!dGa  
public static void sleep(int nSecond) /|v:$iH,C  
{ z'FD{xdf  
try{ T"ors]eI  
Thread.sleep(nSecond); DWT4D)C,U  
} OJ0Dw*K<  
catch(Exception e) KFd !wZ@e  
{ 7[aSP5e>T  
e.printStackTrace (); k=L(C^VP  
} :y#KR\T1  
} <7Igd6u  
agdiJ-lyQ  
//日志 kH$)0n
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public static void log(String sMsg) ?L.c~w;l  
{ woIcW  
System.err.println(sMsg); 0=]RG  
} U6SgV 8  
pI*/-!I  
c}(fmJB&(  
public static void log(int sMsg) ,2h
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{ mNUc g{+/  
System.err.println(sMsg); (5AgI7I,  
} V0yQ  
} t<'-?B2g  
^@V$'Bk  

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/* _c
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**TestMethod.java e]N?{s   
*/ G;r-f63N  
package NetFox; }ti+tM*  
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j(JUOief  
public class TestMethod { eLC}h %  
w s(9@  
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public TestMethod() OFS`?>  
{ ///xx/weblogic60b2_win.exe |%6zhkoufM  
try{ 6uW
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); -8F~Tffx  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); nFE0y3GD8  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Sw!/IPO  
fileFetch.start(); '&~A  
} sR%,l  
catch(Exception e){e.printStackTrace ();} 8'c_&\kdv  
^ 'jJ~U  
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} SVvR]T&_  
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7
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public static void main(String[] args) \gd.Bl
 
{ t%jB[w&,os  
new TestMethod(); N"d*pi#h  
} 6fxf|R\  
} 9r@T"$V#c  
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