http断点续传简单实现（java)

/* 6lob&+  
**SiteFileFetch.java MREB  
*/ >UnLq:
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package NetFox; ]O&\Pn0q  
import java.io.*; 3Pgld*i7  
import java.net.*; Z9q1z~qSQ  
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public class SiteFileFetch extends Thread { ^TEFKx}PX  
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SiteInfoBean siteInfoBean = null; //文件信息Bean LbUH`0:%t  
long[] nStartPos; //开始位置 p`)Mk<`dYD  
long[] nEndPos; //结束位置 M3!4,_!~  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 9Ecc~'f  
long nFileLength; //文件长度 pmc)$3u  
boolean bFirst = true; //是否第一次取文件 ib%'{?Q.  
boolean bStop = false; //停止标志 K1CgM1v  
File tmpFile; //文件下载的临时信息 w0PAtu  
DataOutputStream output; //输出到文件的输出流 R5N~%Dg)3  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） te;VGpv.  
public SiteFileFetch(SiteInfoBean bean) throws IOException :_[pZ;-@  
{ B|ctauJ  
siteInfoBean = bean; UetI4`  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); )nlFyWXh.  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); hMyN$7Z  
if(tmpFile.exists ()) :"'*1S*  
{ O`Y@U?^N  
bFirst = false; !>\g[C  
read_nPos(); KG
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} *FFD G_YG?  
else 0@wXE\s  
{ /BwG\GhM  
nStartPos = new long[bean.getNSplitter()]; 1h3`y  
nEndPos = new long[bean.getNSplitter()]; 0-:dzf  
} %^l&:\ hy  
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}8[  
} /^$n&gI  
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a y$CUw  
public void run() bFVY&  
{ qRL45[ K  
//获得文件长度
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//分割文件 7U:{=+oLR  
//实例FileSplitterFetch v >cPr(  
//启动FileSplitterFetch线程 L),r\#Y(v  
//等待子线程返回 {__NVv  
try{ \$!D^%~;  
if(bFirst) umN4|X  
{ xoQ(GrBY  
nFileLength = getFileSize(); -`D<OSt7  
if(nFileLength == -1) gI00@p:m  
{ "dHo6CT,y_  
System.err.println("File Length is not known!"); )cU$I)  
} w\a6ga!xt"  
else if(nFileLength == -2) S59^$  
{ tA^CuJR  
System.err.println("File is not access!"); l[^0Ik-G  
} Q_`EKz;N{  
else O~|Y#T  
{ xy]oj  
for(int i=0;i<nStartPos.length;i++) z.;!Pj  
{ r<
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); &q +l5L"  
} C=t9P#g*.  
for(int i=0;i<nEndPos.length-1;i++) O
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{ C(vQR~_  
nEndPos = nStartPos[i+1]; Ro=dgQ0:t  
} ,I
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nEndPos[nEndPos.length-1] = nFileLength; vCUbbQz  
} 7n*"9Ai(  
} G
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"A0y&^4B@  
Bm;: cmB0e  
//启动子线程 9W&nAr
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; tBVtIOm9  
for(int i=0;i<nStartPos.length;i++) K/_"ybR7  
{ /vpwpVHIpG  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), a7aj:.wi  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), P1R[M|Fx  
nStartPos,nEndPos,i); yp
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); h)^|VM   
fileSplitterFetch.start(); zU'7x U-  
} 7CwWf  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), S R s  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); .\:MB7p  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", tAkv'
.  
nEndPos = " + nFileLength); 5> !N)pA  
// fileSplitterFetch[nPos.length-1].start(); na@Go@q  
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UE  
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//等待子线程结束 |Mgzb0_IiQ  
//int count = 0; HX ,\a`  
//是否结束while循环 ZC`VuCg2O  
boolean breakWhile = false; iNilk!d6Q3  
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while(!bStop) 6{I6'+K~  
{ ;U#=H9_  
write_nPos(); ^oR qu  
Utility.sleep(500); 4'td6F  
breakWhile = true; Awr(}){  
@"H7Q1Hg!*  
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for(int i=0;i<nStartPos.length;i++) |
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{ H;0K4|I  
if(!fileSplitterFetch.bDownOver) DVf}='en8  
{ 5n1`$T.WG  
breakWhile = false; m'M5O@?  
break; VQ8Fs/Zt!  
} >">Xd@Wk  
} 8#[2]1X^8  
if(breakWhile) f4VdH#eng`  
break; (}s& 84!  
@$nh6l>i  
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2[;  
//count++; ZQn>+c2%!  
//if(count>4) LW#U+bv]Dq  
// siteStop(); +S'm<}"1  
} v+o6ZNX  
'}:(y$9.`  
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System.err.println("文件下载结束！"); pfw`<*e'  
} >vf-,B  
catch(Exception e){e.printStackTrace ();} f:6F5G  
} ^]Q.V  
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ev4_}!  
//获得文件长度 *9|p}q9n  
public long getFileSize() 2:<H)oB  
{ 85
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int nFileLength = -1;
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try{ Y!+H9R  
URL url = new URL(siteInfoBean.getSSiteURL()); Z!*6;[]SfG  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ouO9%)zv  
httpConnection.setRequestProperty("User-Agent","NetFox"); KT+{-"4-  
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int responseCode=httpConnection.getResponseCode(); RJKi98xwJ  
if(responseCode>=400) rITA-W O  
{ R~eLEjezm  
processErrorCode(responseCode); kU#k#4X4g  
return -2; //-2 represent access is error =yoR>llbBC  
} a8-V`  
/F46Ac}I  
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String sHeader; lnK  
7{7Y[F0  
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for(int i=1;;i++) 3177R>0  
{ mwsd
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); apt$e$g  
//Utility.log(in.readLine()); :X:s'I4J D  
sHeader=httpConnection.getHeaderFieldKey(i); Bsha)<  
if(sHeader!=null) @/:7G.  
{ r^H,H'BohJ  
if(sHeader.equals("Content-Length")) /^v!B`A@  
{ 9JX@ck  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); {:3:GdM6  
break;
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} Z>3m-:-e  
} VMe  
else 5g O9 <  
break; n-{d7haOa  
} x+ER 3wDD@  
} ;$e)r3r`LV  
catch(IOException e){e.printStackTrace ();} mSvSdKKKlI  
catch(Exception e){e.printStackTrace ();} U$3DIJVI  
8@LUL)"  
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Utility.log(nFileLength); >P
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return nFileLength; `&'{R<cL  
} :RxMZwa=  
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//保存下载信息（文件指针位置） H=w):kL|  
private void write_nPos() cd=|P?Bi  
{ g'{?j~g  
try{ Ryh 0r  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ^,FG9  
output.writeInt(nStartPos.length); z]-m<#1  
for(int i=0;i<nStartPos.length;i++) <&2<>*/.y  
{ ww[|| =  
// output.writeLong(nPos); BkPt 1i  
output.writeLong(fileSplitterFetch.nStartPos); TU58  
output.writeLong(fileSplitterFetch.nEndPos); gK@`0/k{  
} Hc[@c)DH  
output.close(); ;yyR_NS  
} yla-X|>  
catch(IOException e){e.printStackTrace ();} t_*x.{x-  
catch(Exception e){e.printStackTrace ();} `&h-+  
} i$`o,m#  
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nRu
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//读取保存的下载信息（文件指针位置） e|5@7~Vi  
private void read_nPos() I/!AjB8W4  
{ G-|c%g!ejf  
try{ *uf)t,%  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); >;R`Q9s7  
int nCount = input.readInt(); .MRN)p  
nStartPos = new long[nCount]; 5f?GSHA}  
nEndPos = new long[nCount]; *W`7JL,  
for(int i=0;i<nStartPos.length;i++) uv8kea .(  
{ u[PG/ploc  
nStartPos = input.readLong(); aXG|IN5 *m  
nEndPos = input.readLong(); i+_=7(
e  
} "Da-e\yA  
input.close(); qY'+@^<U;  
} Pk;yn;  
catch(IOException e){e.printStackTrace ();} 1]5k lJ  
catch(Exception e){e.printStackTrace ();} J/E''*  
} Ea][:3  
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private void processErrorCode(int nErrorCode) J~4mp\4b  
{ rx 74v!  
System.err.println("Error Code : " + nErrorCode); 'DNxc  
} kB=B?V~#  
>)='.aR<  
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//停止文件下载 LwxJ:Kz.  
public void siteStop() n4M Xa()P1  
{ 3e47UquZ  
bStop = true; at{p4Sl  
for(int i=0;i<nStartPos.length;i++) Ha/Qz'^S;  
fileSplitterFetch.splitterStop(); =Ul"{T<  
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} !g6=/9  
} lY(_e#  
//负责部分文件的抓取 Z2`M8xEiH  
**FileSplitterFetch.java *?~"Jw  
*/ n7G`b'  
package NetFox; uDkX{<_Xe  
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import java.io.*; S)wP];]`K  
import java.net.*; _&U#*g  
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public class FileSplitterFetch extends Thread { (V&d:tW  
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String sURL; //File URL vnVT0)Lel  
long nStartPos; //File Snippet Start Position MzgP@tB  
long nEndPos; //File Snippet End Position !G\gqkSL  
int nThreadID; //Thread's ID zLJmHb{(  
boolean bDownOver = false; //Downing is over Zi7cp6~7  
boolean bStop = false; //Stop identical NqD Hrx  
FileAccessI fileAccessI = null; //File Access interface zv0sz])  
,7:-V<'Yv  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Vy[xu$y  
{ !.q99DB  
this.sURL = sURL; }F/w34+;  
this.nStartPos = nStart; jP_s(PQ  
this.nEndPos = nEnd; ~_"V7  
nThreadID = id; 8@(?E[&O>  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 @_$$'XA7  
} lF.kAEC  
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public void run() (!N2,1|  
{
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while(nStartPos < nEndPos && !bStop) iu*&Jz)D>  
{ =[!(s/+>L  
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try{ %+,*$wk#*  
URL url = new URL(sURL); PN8#T:E  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #.*&#w)  
httpConnection.setRequestProperty("User-Agent","NetFox"); sR83e|4I  
String sProperty = "bytes="+nStartPos+"-"; _->+Hjj ^  
httpConnection.setRequestProperty("RANGE",sProperty); Sw"h!\c`  
Utility.log(sProperty); P(2OTfGGx  
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InputStream input = httpConnection.getInputStream(); _>;MQ)Km~  
//logResponseHead(httpConnection); 1 hFh F^  
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byte[] b = new byte[1024]; @R%qP>_  
int nRead; O$e"3^Pa  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ",vK~m2W_  
{ z80FMul
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nStartPos += fileAccessI.write(b,0,nRead); .zt&HI.F  
//if(nThreadID == 1)
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^xNzppz`]C  
} 3h=kn@I  
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Utility.log("Thread " + nThreadID + " is over!"); 5Rs#{9YE  
bDownOver = true; 0asP,)i  
//nPos = fileAccessI.write (b,0,nRead); X0^@E  
} /FC HF#yK  
catch(Exception e){e.printStackTrace ();} S2Ez}*plp  
} ,.V<
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} ]dJ"_  
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//打印回应的头信息 !vJ$$o6#  
public void logResponseHead(HttpURLConnection con) <bo)p6S&  
{ v6=%KXSF  
for(int i=1;;i++) o8<~zeI  
{ KN657 |f  
String header=con.getHeaderFieldKey(i); un~`|  
if(header!=null) Gds(.]_  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); & C)
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Utility.log(header+" : "+con.getHeaderField(header)); ,lvG5B\0  
else :2==7u7v?  
break; Cm%I/4  
} f -F}~S  
} o/VT"cT  
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*w _o8!3-  
public void splitterStop() f sh9-iY8e  
{ lkJxb~S  
bStop = true; C"**>OGe  
} +jwk4BU  
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#|Lsi`]+  
} j[A(@w"  
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/* `JiWS
 
**FileAccess.java =Hd#"9-  
*//文件访问(定位，写) 0KgP'oWvY  
package NetFox; |,oLZCNa  
import java.io.*; T!y 9v5  
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public class FileAccessI implements Serializable{ OOXSJE1  
2P8wvNDG  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 w5PscEc  
RandomAccessFile oSavedFile; oNPvksdC;  
long nPos; P)f8lU^z  
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public FileAccessI() throws IOException d ([~o  
{ yc3/5]E&  
this("",0); )}N:t:rry  
} vw3[(_MV3_  
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public FileAccessI(String sName,long nPos) throws IOException c,;VnZ 9wC  
{ E8#aE\'t  
oSavedFile = new RandomAccessFile(sName,"rw"); ~!5Qb{^  
this.nPos = nPos; H9ES|ZJs  
oSavedFile.seek(nPos); "~ $i#  
} ZpOME@9,  
LkzA_|8:D  
:*]#n  
public synchronized int write(byte[] b,int nStart,int nLen) XK/l1E3N  
{ j;y(to-e>D  
int n = -1; 62'9lriQ  
try{ 4Ps;Cor+  
oSavedFile.write(b,nStart,nLen); zw+wq+2"  
n = nLen; Hqs-q4G$  
} Fs4shrt  
catch(IOException e) N_B^k8j  
{ q|]CA  
e.printStackTrace (); _wb]tE ~g  
} l#^?sbG  
%regt{  
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return n; w{[
^  
} FqbGT(QB0  
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} ^8,prxaok  
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/* ;DnUeE8  
**SiteInfoBean.java 5;/q[oXI  
*/ }2RbX,0l9  
package NetFox; E+XS7':I  
&gS-.{w "  
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public class SiteInfoBean { _)= e`9%  
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,
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private String sSiteURL; //Site's URL aLm~.@Q  
private String sFilePath; //Saved File's Path kBC$dW-  
private String sFileName; //Saved File's Name lv!
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private int nSplitter; //Count of Splited Downloading File T>(X`(  
&)t
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public SiteInfoBean() l%mp49<  
{//nSplitter的缺省值为5 >S}X)4  
//default value of nSplitter is 5 hwe6@T.#  
this("","","",5); 7Rtjm  
} @o?Y[BR  
7
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) PbvA~gm  
{ fOSk> gK  
sSiteURL= sURL; ]C"?xy  
sFilePath = sPath; 4l*cX1!  
sFileName = sName; o@360#njF  
this.nSplitter = nSpiltter; f!YlYk5  
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nxuH22:  
} ALF21e*n  
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public String getSSiteURL() 3D@3jyo:  
{ c9jS !uDMK  
return sSiteURL; n>eDN\5  
} eA]8M^  
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4,:I{P_>6B  
public void setSSiteURL(String value) kGnT4R*E  
{ 1CZO+MB&"$  
sSiteURL = value; d42Y`Wu  
} \/ri|fm6l#  
+\ "NPK@3  
.7Yox1,  
public String getSFilePath() 5({_2meJ:  
{ @IbZci)1  
return sFilePath;  H6nH  
} Y$,~"$su|  
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public void setSFilePath(String value) V+lS\E.  
{ Z5U\>7@&8  
sFilePath = value; G^h:#T
  
} "S'Yn-  
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*rxYal4ad  
public String getSFileName() g.62XZF@  
{ qk^/&j  
return sFileName; |/xA5_-N  
} ~};q/-[r  
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public void setSFileName(String value) sx7zRw >X  
{ T3=h7a %=  
sFileName = value; [x, `)Fk  
} -:r<sv$  
0>-}c>  
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public int getNSplitter() xuqG)HthRS  
{ w1zMY
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return nSplitter; |%XcI3@*  
} }JQy&V%  

b[:m[^  
~-H3]  
public void setNSplitter(int nCount) ?771e:>S-  
{ m0.g}N-w  
nSplitter = nCount; }zkF
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} lZIJ[.  
} jzpDKc%  
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^a /q6{  
/*
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**Utility.java ()Wu_Q  
*/ jFKp~`/#  
package NetFox; (#85<|z  
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public class Utility { cotySio$  
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public Utility() lJfk4 -;M  
{ *a8<cf  
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} b$nev[`{6  
2-UD^;0  
//线程睡眠 $g VbeQ  
public static void sleep(int nSecond) >;j&]]-&  
{ W79.Nj2`  
try{ qG~6YCqii  
Thread.sleep(nSecond); `?l /HUw  
} yXEI%2~)  
catch(Exception e) <f.Eog  
{ .
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e.printStackTrace (); {gu3KV  
} |}YxxeAk  
} ;{R;lF,  
jHHCJOHB8  
//日志 OA}; pQ9QN  
public static void log(String sMsg) Ke:EL;*8k  
{ qvWi;  
System.err.println(sMsg); sL\ {.ad5  
} 5"1wz  
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public static void log(int sMsg) x2HISxg  
{ PMb
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System.err.println(sMsg); T <k;^iqR  
} D-i, C~W  
} 6'uCwAQU  
t3^`:T\  
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/* iY,oaC~?"N  
**TestMethod.java qZV|}M>P)  
*/ j}tGcFwvSN  
package NetFox; ^ )!eiM  
8sI$  
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public class TestMethod { sc# EL~  
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public TestMethod() _):@C:6  
{ ///xx/weblogic60b2_win.exe ;P
8%yf  
try{ `YZl2c<w*  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); tGXH)=K  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); \WdSj  
SiteFileFetch fileFetch = new SiteFileFetch(bean); x\:KfYr4Y;  
fileFetch.start(); br k
*;  
} +`mI\+y,  
catch(Exception e){e.printStackTrace ();} <rui\/4NJ  
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} bF,.6iKI  
't
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public static void main(String[] args) ku}`PS0UGd  
{ o>yXEg  
new TestMethod(); MwQt/Qv=  
} d, ?GW  
} # SJJ@SM  
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