http断点续传简单实现（java)

/* =C^4nP-  
**SiteFileFetch.java zmFKd5  
*/ 3JF" O+@  
package NetFox; UH5A;SrTqR  
import java.io.*; z<cPy)F]"  
import java.net.*; ySlGqR1H  
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public class SiteFileFetch extends Thread { `@<)#9'A  
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SiteInfoBean siteInfoBean = null; //文件信息Bean %=vU Z4  
long[] nStartPos; //开始位置 U[ogtfv`
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long[] nEndPos; //结束位置 qvJQbo[.9P  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 WBD"
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long nFileLength; //文件长度 >IZ$ .-  
boolean bFirst = true; //是否第一次取文件 `n`HwDo;i  
boolean bStop = false; //停止标志 2kFP;7FO  
File tmpFile; //文件下载的临时信息 E@Yq2FBpnn  
DataOutputStream output; //输出到文件的输出流 j4(f1  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） _Vt CC
/  
public SiteFileFetch(SiteInfoBean bean) throws IOException I$fm"N  
{ `TDS4Y  
siteInfoBean = bean; TSRl@QVy  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); RAxp2uif  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 0(A&m ,  
if(tmpFile.exists ()) S\2@~*{-
8  
{ z&.F YGq}  
bFirst = false; XpT~]q}  
read_nPos(); _=I&zUF  
} (Ii+}Mfp  
else e{ZS"e`!  
{ &&sm7F%  
nStartPos = new long[bean.getNSplitter()]; S$GWY^5}{  
nEndPos = new long[bean.getNSplitter()]; lygv#s-T  
} q9$K.=_5  
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} .H86f !=  
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public void run() wJWofFz  
{ Gnie|[3  
//获得文件长度 9Om3<der  
//分割文件 >#5jO9  
//实例FileSplitterFetch mk3,ke8  
//启动FileSplitterFetch线程 9H cxL  
//等待子线程返回 :-T[)Q+-3  
try{ VzuU0  
if(bFirst) nS^,Sq\Ak  
{ QM=Y}   
nFileLength = getFileSize(); @dhnpR:L  
if(nFileLength == -1) 6J3<k(#:  
{ qoC<qn{.a  
System.err.println("File Length is not known!"); ,mE}#cyY  
} 6dqI{T-i?  
else if(nFileLength == -2) *XG.?%x*|  
{ K'U=);W  
System.err.println("File is not access!"); VO,F[E~_  
} R9~c: A4G  
else $1|65j[e  
{ )!=X?fz,O  
for(int i=0;i<nStartPos.length;i++) AhNz[A  
{ p$,ZYF~  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Ce@"+k+w  
} poS=8mN8;  
for(int i=0;i<nEndPos.length-1;i++) bxAHzOB(\  
{ @`rC2-V  
nEndPos = nStartPos[i+1]; {$_Gjv  
} .oe\wJS6  
nEndPos[nEndPos.length-1] = nFileLength; 2<uBC  
} }^*m0`H  
} xyi4U(;  
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+)*oPSQ5  
//启动子线程 f2i9UZ$=e!  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; xbZR/!?  
for(int i=0;i<nStartPos.length;i++) LP//\E_]  
{ =5 $BR<'  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3 E!F8GZ  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), a)M3t  
nStartPos,nEndPos,i); -nGLmMvd  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); P,K^oz}  
fileSplitterFetch.start(); EnYEAjX  
} ?p &Xf>K  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), J L2g!n= K  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 'LLpP#(  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $8NM[R.8^4  
nEndPos = " + nFileLength); `Wp& 'X  
// fileSplitterFetch[nPos.length-1].start(); #} `pj}tQ
 
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//等待子线程结束 :}ZY*ind  
//int count = 0; "V<7X%LIX  
//是否结束while循环 _16r8r$V  
boolean breakWhile = false; D#d \1g  
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while(!bStop) O7zj8  
{ ?q}:ojrs1  
write_nPos(); }_9yemP  
Utility.sleep(500); vH>s2\V"  
breakWhile = true; )*
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for(int i=0;i<nStartPos.length;i++) O+ J0X*&x  
{ /*m6-DC  
if(!fileSplitterFetch.bDownOver) (*V:{_r  
{ H:,Hr_;nC  
breakWhile = false; v=?
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break; 7y=1\K
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} CjmF2[|  
} OBnvY2)Ri  
if(breakWhile) uB+:sX-L  
break; XOPiwrg%p  
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//count++; ~Da-|FKa>  
//if(count>4) QT[4\)  
// siteStop(); L [X"N  
} kC/An@J^#  
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System.err.println("文件下载结束！"); 7J5Yzu)D  
} Xrzpn&Y=#  
catch(Exception e){e.printStackTrace ();} F
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} w)"F=33}5  
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//获得文件长度 Q`z2SYz>  
public long getFileSize() 9PJnKzQ4  
{ NdM \RD_R  
int nFileLength = -1; zl)r3#6hW  
try{ xgZ<.r  
URL url = new URL(siteInfoBean.getSSiteURL()); [lE^0_+  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :Oi}X7\  
httpConnection.setRequestProperty("User-Agent","NetFox"); a*!9RQ  
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int responseCode=httpConnection.getResponseCode(); ?fNUmk^A<  
if(responseCode>=400) G
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{ ,o [FUi(#@  
processErrorCode(responseCode); dG}*M25  
return -2; //-2 represent access is error ]|B_3*A  
} :<,tGYg/!  
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String sHeader; P B{7u  
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for(int i=1;;i++) hj=k[t|g}  
{ Fuo.8  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ,gIeQ!+vy  
//Utility.log(in.readLine()); OwLJS5r@<-  
sHeader=httpConnection.getHeaderFieldKey(i); fTd":F  
if(sHeader!=null) C0H@  
{ WM GiV  
if(sHeader.equals("Content-Length")) )T'~F  
{ mJME1#j$/|  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); =Kt!+^\")  
break; UW-`k1  
} ^'4I%L"  
} -z>m]YDH  
else SHqz&2u  
break; Gc<^b  
} L:Me  
} ^[1Xl7)`  
catch(IOException e){e.printStackTrace ();} \d QRQL{LL  
catch(Exception e){e.printStackTrace ();} qmq#(%Z <W  
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Utility.log(nFileLength); , 4@C%  
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return nFileLength; 2Kw i4R  
} NtQ#su$  
/X?%K't2r  
L}>ts(!q&  
//保存下载信息（文件指针位置） K#dG'/M|Pb  
private void write_nPos() Ss'Dto35Q  
{ |kqRhR(Ei  
try{ &8hW~G>(m  
output = new DataOutputStream(new FileOutputStream(tmpFile)); k j&hn  
output.writeInt(nStartPos.length); L%/atl!  
for(int i=0;i<nStartPos.length;i++) 7h\U}!  
{ QX+&[G!DZH  
// output.writeLong(nPos); dSbz$Fct  
output.writeLong(fileSplitterFetch.nStartPos); sUpSXG-W/@  
output.writeLong(fileSplitterFetch.nEndPos); Dos';9Uq  
} ^fti<Lw5  
output.close(); hIwqSKq9  
} W7.QK/@  
catch(IOException e){e.printStackTrace ();} l:s
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catch(Exception e){e.printStackTrace ();} +e&Q<q!,q  
} f&C]}P  
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//读取保存的下载信息（文件指针位置） >;~ia3  
private void read_nPos() 2jyxP6t  
{ `6o5[2V  
try{ I<hMS6$<LE  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 7:wf!\@I  
int nCount = input.readInt(); 36
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nStartPos = new long[nCount]; FK;2u$
:  
nEndPos = new long[nCount]; M3H^s_  
for(int i=0;i<nStartPos.length;i++) v|2+7N:[;  
{ !GtCOr\'  
nStartPos = input.readLong(); 6jz~q~I  
nEndPos = input.readLong(); =${ImMwj  
} # 0/,teJk  
input.close(); b%e7rY2  
} l,ra
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catch(IOException e){e.printStackTrace ();} d 2z!i^:  
catch(Exception e){e.printStackTrace ();} I3dUI~}u  
} ='fN xabB  

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private void processErrorCode(int nErrorCode) ]?~[!&h  
{ $H1igYc  
System.err.println("Error Code : " + nErrorCode); A"~Oi  
} -7A2@
g  
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&dJ\}O[r  
//停止文件下载 3s Mmg`  
public void siteStop() \n0MqXs#  
{ ShMP_?]P  
bStop = true; 6?= ^8  
for(int i=0;i<nStartPos.length;i++) tflUy\H>  
fileSplitterFetch.splitterStop(); 4_o+gG%HaM  
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} _cQhT  
} B
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//负责部分文件的抓取 kj'  
**FileSplitterFetch.java xd]7?L@h.I  
*/ _ Zzne  
package NetFox; W";Po)YC  
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import java.io.*;
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import java.net.*; tDNo; f  
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public class FileSplitterFetch extends Thread { 9a{9|p
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String sURL; //File URL fx/If  
long nStartPos; //File Snippet Start Position fl<j]{*v  
long nEndPos; //File Snippet End Position #\MkbZc d  
int nThreadID; //Thread's ID G3de<?K.[V  
boolean bDownOver = false; //Downing is over eLk:
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boolean bStop = false; //Stop identical &_$xMM,X  
FileAccessI fileAccessI = null; //File Access interface D?r% Y  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 4j~WrdI*  
{ A|BN>?.t  
this.sURL = sURL; s7:w>,v/  
this.nStartPos = nStart; ]V
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this.nEndPos = nEnd; o^<W3Z  
nThreadID = id;  fG|+!  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 10$:^  
} @wa<nYd  
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public void run() )Tad]Hd"W  
{ :c0 |w  
while(nStartPos < nEndPos && !bStop) &Y$)s<u8.  
{ KPdlg.  
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try{ Owm2/  
URL url = new URL(sURL); +c\uBrlZQ;  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); YPS,[F'B.  
httpConnection.setRequestProperty("User-Agent","NetFox"); jQ5FvuNOy  
String sProperty = "bytes="+nStartPos+"-"; #5_pE1  
httpConnection.setRequestProperty("RANGE",sProperty); 7kQ,D,c'  
Utility.log(sProperty); -|_io,eL;  
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InputStream input = httpConnection.getInputStream(); FSS~E [(DL  
//logResponseHead(httpConnection); J*]JH{  
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byte[] b = new byte[1024]; .;NoKO7)  
int nRead;  h]?[}&  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ((tWgSZ3  
{ "gq_^&  
nStartPos += fileAccessI.write(b,0,nRead); L&qY709  
//if(nThreadID == 1) Oa-~}hN  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); lK #~lC  
} [
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9XW[NY#)#  
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Utility.log("Thread " + nThreadID + " is over!"); a1A3uP  
bDownOver = true; kF7`R4Sz  
//nPos = fileAccessI.write (b,0,nRead); ,4kipJ!,yK  
} (r$QQO)/  
catch(Exception e){e.printStackTrace ();} W^dRA xVX  
} T( sEk  
} _ +A$6l  
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q<?r5H5  
//打印回应的头信息 T!gq Z  
public void logResponseHead(HttpURLConnection con) ^HNccr  
{ 0vdnM8N2  
for(int i=1;;i++) *Y- rEF>  
{ @!s(Zkpev  
String header=con.getHeaderFieldKey(i); BZ@v8y _TA  
if(header!=null) Wx-rW  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ,ikn%l#cm  
Utility.log(header+" : "+con.getHeaderField(header));
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else B,RHFlp{  
break; ~n!7 ?4%U  
} SLI358]$<  
} e+P|PW  
)lB*] n`Z]  
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public void splitterStop() 9/LJtM  
{ g;<_GL  
bStop = true; ut;KphvSH  
} D_Cd^;b  
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} ?c#v'c^=h  
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/* >rzpYc'~w  
**FileAccess.java S]&
7  
*//文件访问(定位，写) &1,qC,:!  
package NetFox; AJ-~F>gn  
import java.io.*; <D{_q.`vA  
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{ w:9w  
public class FileAccessI implements Serializable{ XP_V  
n{r
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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 0P6< 4  
RandomAccessFile oSavedFile;
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long nPos; E| =~rIKN  
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public FileAccessI() throws IOException J0"<}"  
{ ?$FvE4!n  
this("",0); L[9]Ez$2+  
} s7TV@Y)  
h`$2/%?  
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public FileAccessI(String sName,long nPos) throws IOException \m;"KyP+  
{ xT1{O`  
oSavedFile = new RandomAccessFile(sName,"rw"); p&ml$N9fd  
this.nPos = nPos; v_Y'o _  
oSavedFile.seek(nPos); j=,]b6(  
} WgQ6EV`  
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public synchronized int write(byte[] b,int nStart,int nLen) SvR? nN|  
{ ZICcZG_y  
int n = -1; {,rVA(I@  
try{ f; 1C)  
oSavedFile.write(b,nStart,nLen); kKg%[zXS  
n = nLen; g>*t"Rf:  
} y*Wl(w3  
catch(IOException e) E-q*u(IW  
{ z!6:Dt6^  
e.printStackTrace (); l+1GA0'JP  
} |J#mgA}(  
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return n; &D 4Ci_6k  
} _GK3]F0  
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} `Dco!ih  
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h^KLqPBt{  
/* 13nXvYo'  
**SiteInfoBean.java "m:4e`_dz  
*/ D*R49hja{  
package NetFox; tgbr/eCoU  
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public class SiteInfoBean { Dj9).lgc  
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private String sSiteURL; //Site's URL $lMEZt8A  
private String sFilePath; //Saved File's Path r%/*,lLO  
private String sFileName; //Saved File's Name H]7;OM/g  
private int nSplitter; //Count of Splited Downloading File 3yfq*\_uXw  
)} H46  
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public SiteInfoBean() c{u~=24;%#  
{//nSplitter的缺省值为5 4F+n`{~  
//default value of nSplitter is 5 VfiMR%i}  
this("","","",5); NN9`jP2  
} H `V3oS~}  
(fjAsbT  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) /8SQmh$+e  
{ 6*<=(SQI  
sSiteURL= sURL; nVC:5ie  
sFilePath = sPath; 1wa zJj=v  
sFileName = sName; a!>yX ex  
this.nSplitter = nSpiltter; I!ykm\<  
bVc;XZwI  
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} kMHupROj  
^c{,QS{  
'}{J;moB  
public String getSSiteURL() N'nqVYTU  
{ -/.Xf<y58  
return sSiteURL; ji[O?  
} I%NPc4p  
|6pNe T[  
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public void setSSiteURL(String value) 7lvUIc?krW  
{ I9`R LSn  
sSiteURL = value; Oop;Y^gG}  
} KGclo-,  
H3"[zg9L:a  
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public String getSFilePath() o[bG(qHZ  
{ wr=h=vXU[  
return sFilePath; ,f4mFL0~N  
} bg'B^E3  
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public void setSFilePath(String value) oOhm`7iy  
{ e4V4%Q
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sFilePath = value; {P_~_5o_  
} >69+e+|I  
$Wy7z^t  
nz|;6?LCLY  
public String getSFileName() NW`.RGLI<  
{ xP.B,1\X  
return sFileName; ,x?H]a)  
} ^IxT.g  
g< cR/  
,*2%6t`N?  
public void setSFileName(String value) UlHRA[SCv  
{ R<gC,eV<=  
sFileName = value; 0}YR=  
} -~A7o3k35  
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public int getNSplitter() 0KyujU?sF  
{ )""i"/Mn  
return nSplitter; OYJy;u3"  
} 2sjP"
:  
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BYEqTwhT&  
public void setNSplitter(int nCount) w0Fi~
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{ \`#;J?Y|`F  
nSplitter = nCount; ,epKt(vl  
} {4 !%'~  
} O~g_rcG  
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/* K,[g<7X5  
**Utility.java 2*
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*/ aTs5^Kh')  
package NetFox; f- pt8  
:<=!v5 SK  
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public class Utility { <
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public Utility() 36JVnW;  
{ . ({aPtSt!  
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|EaGKC(   
} VuwBnQ.2k  
j?1\E9&4-Q  
//线程睡眠 {nT !|S)$  
public static void sleep(int nSecond) -[s*R%w  
{ g*ES[JJH&  
try{ FyYQ4ov0&o  
Thread.sleep(nSecond); Q;{yIa$ $  
} !o*BRR*  
catch(Exception e) 6)P~3C'  
{ fcb:LPk;  
e.printStackTrace (); U KF/v
 
} qt}vM*0}V  
} }1w[G;$  
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//日志 *Xt#04_  
public static void log(String sMsg) !h7`W*::  
{ Ly\$?3h  
System.err.println(sMsg); RMDs~  
} m?xzx^xs/  
!,Wd$UK  
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public static void log(int sMsg) =2bW"gs I  
{ je.jui"  
System.err.println(sMsg); (`4^|_gw  
} SY["(vP%#  
} kmM_Af&
 
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6}IOUWLB@  
/* 8iD_md_[  
**TestMethod.java kj
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*/
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package NetFox; *(L4
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public class TestMethod { <(?ahO5  
jt tlzCDn  
OnF+  
public TestMethod() @\Sa)  
{ ///xx/weblogic60b2_win.exe oScHmGFv  
try{ Jd&Qi)1  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); P /wc9Yt  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); a<sEdp  
SiteFileFetch fileFetch = new SiteFileFetch(bean); sU4(ed\gI\  
fileFetch.start(); :q;vZ6Xd  
} Vlce^\s;  
catch(Exception e){e.printStackTrace ();} -hL8z
$}  
5|xFY/%  
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} 1QE-[|  
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Q <^'v>~n  
public static void main(String[] args) d#I'9O0&  
{ k$}XZ,Q  
new TestMethod();
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} ,Zzh.z::D  
} %fh ,e5(LT  
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