http断点续传简单实现（java)

/* vd;wQ  
**SiteFileFetch.java T8\,2UWsj2  
*/ LNg1q1P3  
package NetFox; :{AN@zC0\  
import java.io.*;
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import java.net.*; "s*{0'jo  
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public class SiteFileFetch extends Thread { cshUxabB  
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SiteInfoBean siteInfoBean = null; //文件信息Bean L fi]s  
long[] nStartPos; //开始位置 }
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long[] nEndPos; //结束位置 PY2`RZ/@  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 9w(j2i q  
long nFileLength; //文件长度 K1hw'AaQ  
boolean bFirst = true; //是否第一次取文件 OYzJE@r^  
boolean bStop = false; //停止标志 _+. t7q^  
File tmpFile; //文件下载的临时信息 u,pm\  
DataOutputStream output; //输出到文件的输出流 {NFeX'5bP  
y, Z
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ::R^ w"  
public SiteFileFetch(SiteInfoBean bean) throws IOException a} /Vu"  
{ jn7}jWA  
siteInfoBean = bean; gPfaiVY  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); :Hd<S  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); m<yA] ';s  
if(tmpFile.exists ()) J8%|Gd0#4  
{ V.F 's(o  
bFirst = false; nFP2wvFM  
read_nPos(); P]TT  
} Brl6r8LGi  
else EvYw$
j  
{ <Kh\i'8  
nStartPos = new long[bean.getNSplitter()]; ZJ4"QsF  
nEndPos = new long[bean.getNSplitter()]; Y[H_?f=;%  
} .xx#>Y-\  
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} J!H5{7.efN  
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public void run() `%=Jsi0.Nq  
{ bXW)n<y  
//获得文件长度 J.&q[  
//分割文件 sH]AB=_  
//实例FileSplitterFetch *HC8kD a%$  
//启动FileSplitterFetch线程 Y1~SGg7(@  
//等待子线程返回 {, |"Rpd  
try{ `~}7k)F(  
if(bFirst) bDkE*4SRX  
{ UVLcR  
nFileLength = getFileSize(); 5B
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if(nFileLength == -1) z>{KeX:  
{ d3$<|mG$  
System.err.println("File Length is not known!"); Lr^xp,_n  
} g IKm  
else if(nFileLength == -2) H>]z=w~  
{ Pjy?&;GvT  
System.err.println("File is not access!"); Mz^s^aJEE  
} |:?.-tq  
else KFhn}C3 i  
{ YfalsQ8  
for(int i=0;i<nStartPos.length;i++) q!TbM"  
{ ~Qsj)9
 
nStartPos = (long)(i*(nFileLength/nStartPos.length)); $O>@(K  
} Jv<)/Km`  
for(int i=0;i<nEndPos.length-1;i++) Id*^H:]C#  
{ %(Ys-GeGr  
nEndPos = nStartPos[i+1]; ""+*Gn7^8  
} 8.^U6xA  
nEndPos[nEndPos.length-1] = nFileLength; ;?!
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} E oR(/*'  
} OT[m g4&  
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7`/qL "  
//启动子线程 rrWk&;?  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]aRD6F:L  
for(int i=0;i<nStartPos.length;i++) qWpCe*C  
{ &V3oW1*W  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ) T1oDk  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), *N r|G61  
nStartPos,nEndPos,i); >FHsZKJ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -IS9uaT5  
fileSplitterFetch.start(); /R
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} Yel(}Ny  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2P ?Iu&  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); >>cd3)b  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Bg
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nEndPos = " + nFileLength); 0q>lW &J  
// fileSplitterFetch[nPos.length-1].start(); r8%,xA&  
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//等待子线程结束 [8P2V  
//int count = 0; +E~`H^  
//是否结束while循环 Z ~9N  
boolean breakWhile = false; PoJyWC  
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while(!bStop) zrO|L|F&P  
{ ss{=::#  
write_nPos(); ws?s  
Utility.sleep(500); I0vnd7  
breakWhile = true; D,j5k3< #  
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for(int i=0;i<nStartPos.length;i++) FBAC9}V"  
{ } XU:DE  
if(!fileSplitterFetch.bDownOver) kV3j}C"  
{ E@6r{uZ#  
breakWhile = false; $tHwJ!<$&  
break; &U*J{OP
|  
} !O6Is'%B  
} ls\E%d  
if(breakWhile) 1!wEXH(  
break; &i^NStqu  
yn[ZN-H~
  
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//count++; 9sjW  
//if(count>4) 8@KFln )[  
// siteStop();  KdJx#Lc  
} Qf>Pb$c$U  
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System.err.println("文件下载结束！"); XHM"agrhSQ  
} W+ '}O<  
catch(Exception e){e.printStackTrace ();} 7B\(r~f`t  
} ]3,.g)U*m  
r_,m\'~s!  
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//获得文件长度 YIQ]]q8R!L  
public long getFileSize() z~e~K`S  
{ R(83E B~_  
int nFileLength = -1; nvK7*-  
try{ <`_OpNxqW  
URL url = new URL(siteInfoBean.getSSiteURL()); niEEm`"  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); fKz"z{\,0  
httpConnection.setRequestProperty("User-Agent","NetFox"); j4xr1y3^  
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int responseCode=httpConnection.getResponseCode(); %)Uvf`Xhh4  
if(responseCode>=400) h_chZB
'  
{ d3G{0PX  
processErrorCode(responseCode); {&EZ>r-  
return -2; //-2 represent access is error P"uHtHK  
} $:E}Nj]{&  
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String sHeader; $`5lvy^  
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for(int i=1;;i++) o+_/)c  
{ iQzX-a|4]  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); T[XP\!z]B!  
//Utility.log(in.readLine()); \*%i#]wO@  
sHeader=httpConnection.getHeaderFieldKey(i); 9X$#x90  
if(sHeader!=null) uWB:"&!^  
{ T E&Q6  
if(sHeader.equals("Content-Length")) /1W7<']>xV  
{ n*i'vtQ8  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ow+Dd[i  
break; EdAR<VfleA  
} A]iv
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} k g,ys4  
else hHc^ZA  
break; RQpIBsj  
} 2WPF{y%/  
} QPe9s[Y  
catch(IOException e){e.printStackTrace ();} ]fADaw-R  
catch(Exception e){e.printStackTrace ();} .5!sOOs$P  
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Utility.log(nFileLength); Z&]+A,  
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return nFileLength; N+s?ZE*  
} ,t%\0[{/B  
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//保存下载信息（文件指针位置） ZcTL#OTP  
private void write_nPos() MLt'YW^  
{ U+*oI*  
try{ C~KWH@  
output = new DataOutputStream(new FileOutputStream(tmpFile)); xQ#Akd=  
output.writeInt(nStartPos.length); (9KDtr*(2i  
for(int i=0;i<nStartPos.length;i++) =(.mf  
{ V%BJNJ  
// output.writeLong(nPos); 5fegWCJ  
output.writeLong(fileSplitterFetch.nStartPos); -4vHK!l  
output.writeLong(fileSplitterFetch.nEndPos); (K*/Vp  
} &e ?"5  
output.close(); UbY~xs7_  
} ii_|)udz  
catch(IOException e){e.printStackTrace ();} :m*!?QGdL  
catch(Exception e){e.printStackTrace ();} G9i&#)nWr  
} Db#W/8 a8k  
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//读取保存的下载信息（文件指针位置） \[[TlB>  
private void read_nPos() d=t}T6.|  
{ sb}K%-  
try{ h0F0d^W.  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); P /c Q1  
int nCount = input.readInt(); Zk/' \(5  
nStartPos = new long[nCount]; *(d6Z#  
nEndPos = new long[nCount]; s%N`  
for(int i=0;i<nStartPos.length;i++) Mhv1K|4s  
{ }fJ:wku  
nStartPos = input.readLong(); rnn2u+OG  
nEndPos = input.readLong(); {d1N&  
} ]27>a"p59Y  
input.close(); FJa[ToZ4+  
} U]
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catch(IOException e){e.printStackTrace ();} I|KY+k> /  
catch(Exception e){e.printStackTrace ();} 8h&oSOkQk,  
} hv$uH7Fz  
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private void processErrorCode(int nErrorCode) ka5#<J7<p  
{ {PODisl>\D  
System.err.println("Error Code : " + nErrorCode); W;Ud<7<;Z  
} j-lSFTo  
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//停止文件下载 JrCf,?L^  
public void siteStop() L_THU4^j  
{ mL:m;>JJ n  
bStop = true; DKy>]Hca  
for(int i=0;i<nStartPos.length;i++) c*x J=Gz6d  
fileSplitterFetch.splitterStop(); QKp+;$SE'  
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.
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} MxO W)$f  
} h8f!<:rTS  
//负责部分文件的抓取 I
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**FileSplitterFetch.java ,|T*|2Gm  
*/ M82.khm~jM  
package NetFox; {S5RK-ax  
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= n+q_.A  
import java.io.*; 81GQijq  
import java.net.*; >_;kTy,  
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public class FileSplitterFetch extends Thread { {0is wq'J  

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String sURL; //File URL W(;x\Nc7  
long nStartPos; //File Snippet Start Position zKIGWH=qqm  
long nEndPos; //File Snippet End Position ;_mgiKHg  
int nThreadID; //Thread's ID %04:z77  
boolean bDownOver = false; //Downing is over i{o#3  
boolean bStop = false; //Stop identical [Ja)<!]<  
FileAccessI fileAccessI = null; //File Access interface _1I K$gb[  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException r_b8,I6{]  
{ v6wRME;JA  
this.sURL = sURL; JB&G~7Q85  
this.nStartPos = nStart; 3p:=xL  
this.nEndPos = nEnd; Z5((1J9  
nThreadID = id; ?qju DD  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 d{er|$E?  
} B4`2.yRis  
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public void run() }5Yj  
{ iaY5JEV:CA  
while(nStartPos < nEndPos && !bStop) aXMv(e+  
{ yC0C`oC  
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try{ ^'m\D;
 
URL url = new URL(sURL); *6:v}#b[  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();  b<[jaI0  
httpConnection.setRequestProperty("User-Agent","NetFox"); xC<=~(  
String sProperty = "bytes="+nStartPos+"-"; qs=Gj?GwGQ  
httpConnection.setRequestProperty("RANGE",sProperty); *i@sUM?K  
Utility.log(sProperty); ,Z^Ca15z  
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InputStream input = httpConnection.getInputStream(); he"L*p*H  
//logResponseHead(httpConnection); 3)}(M
 
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byte[] b = new byte[1024]; $30oc Tt{  
int nRead; *'6s63)I2  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) *RBV'b  
{ fV 3r|Bp  
nStartPos += fileAccessI.write(b,0,nRead); bG"HD?A_  
//if(nThreadID == 1) "jT#bIm  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1@xP(XS  
} )B6
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Utility.log("Thread " + nThreadID + " is over!"); ^EF

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bDownOver = true; yf!,4SUkU  
//nPos = fileAccessI.write (b,0,nRead); :Zza)>l  
} UVrQV$g!  
catch(Exception e){e.printStackTrace ();} -LTKpN`[@  
} wzd`l?o,  
} ndw7v  
#<4--$Xo  
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//打印回应的头信息 @dl8(ILk'  
public void logResponseHead(HttpURLConnection con) >)Ioo$B  
{ +]c/&Xo!  
for(int i=1;;i++) WSRy%#  
{ P|N2R5(>T  
String header=con.getHeaderFieldKey(i); G8eD7%{b:)  
if(header!=null) e&0K;yU  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ?OE#q$g  
Utility.log(header+" : "+con.getHeaderField(header)); D|l,08n"?  
else r4u z} jl{  
break; F|Q H
 
} w]nX?S8  
} 9t?L\
  
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public void splitterStop() kx:j
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{ qNxB{0(D  
bStop = true; VevNG*  
} 8u>gbdU  
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} e`iEy=W  
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/* F)SPaC4  
**FileAccess.java ]3ifdGk  
*//文件访问(定位，写) aE)by-'  
package NetFox; T/l1qcf`wT  
import java.io.*; Lg4YED9#  
/ylc*3e'4  
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public class FileAccessI implements Serializable{ )#C mQXgG  
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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 L&kr{7q  
RandomAccessFile oSavedFile; X`:'i?(yj  
long nPos; <^8*<;PaG  
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XN#&NT{t}  
public FileAccessI() throws IOException +BL{@,zr  
{ $ J1f.YE  
this("",0); w2
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} C5*xQlCq}  
| kXm}K  
};b1ahaG  
public FileAccessI(String sName,long nPos) throws IOException \S ."?!U  
{ booRrTS  
oSavedFile = new RandomAccessFile(sName,"rw"); .TpsJXF  
this.nPos = nPos; M:n6BC>t"  
oSavedFile.seek(nPos); ~Y7dH Dn  
} Vn, ><g  
q/PNJ#<  
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public synchronized int write(byte[] b,int nStart,int nLen) p=Y>i 'CG  
{ ;b0NGa(k  
int n = -1; 7 ^$;  
try{ <+v{GF#R  
oSavedFile.write(b,nStart,nLen); o&SSvW  
n = nLen; z-r2!^q27  
} r2\c'9uH  
catch(IOException e) -Q"hZ9  
{ j}f[W [2  
e.printStackTrace (); HC*?DJ,  
} RLVATM5  
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return n; @?kJ).  
} #_JYh?  
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} O )d[8jw"  
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/* wTc)S6%7  
**SiteInfoBean.java j:,9%tg  
*/ 91Z'  
package NetFox; Vzg=@A#  
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public class SiteInfoBean { -_N)E ))G  
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private String sSiteURL; //Site's URL %*}Y6tl'|  
private String sFilePath; //Saved File's Path "ju'UOcS/  
private String sFileName; //Saved File's Name iE].&>w  
private int nSplitter; //Count of Splited Downloading File F@YKFk+a  
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public SiteInfoBean() EGVM)ur  
{//nSplitter的缺省值为5 eWs&J24  
//default value of nSplitter is 5
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this("","","",5); Ib=x~za@n  
} qv*7K@  
@N@F,~[RR2  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) fmX!6Kv  
{ r6Aneg7  
sSiteURL= sURL; Yk!/ow@.  
sFilePath = sPath; 0RFRbi@n(  
sFileName = sName; nh+l78  
this.nSplitter = nSpiltter; Z4b||  
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} h^UKT`9vt  
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public String getSSiteURL() /]
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{ GL$De,V  
return sSiteURL; X{xBYZv4  
} #%0Bx3uM  
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public void setSSiteURL(String value) "R>FqX6FB  
{ CusF/>  
sSiteURL = value; j=RRfFg)  
} o\b-_E5"?  
2_^aw[-  
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public String getSFilePath() :rMM4  
{ MRNNG6TUs  
return sFilePath; ED>prE0  
} tJViA`@x  
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"*1f;+\  
public void setSFilePath(String value)  {^a36i  
{ D,v U  
sFilePath = value; "\C$   
} Yb3mP!3q8Z  
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public String getSFileName() nAIo{ F  
{ s#~GH6/  
return sFileName; YHk
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} E>'a,!QPv  
c/N@zum,{  
"5R~(+~<@  
public void setSFileName(String value) \MC-4Yz  
{ EP'h@zdz  
sFileName = value; q;g>t5]a  
} l/TjQ*
 
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public int getNSplitter() }D41
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{ a7zcIwk '{  
return nSplitter; . o7m!  
} `nM/l@
 
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public void setNSplitter(int nCount) #} ~qqJ G2  
{ -}O1dEn.  
nSplitter = nCount; L37Y+C//  
} {vUN+We  
} &,A64y  
?Nf>]|K:Q  
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/* (~CLn;'  
**Utility.java AjcX  N  
*/ MYJg8 '[j  
package NetFox; _vSn`  
*n"/a{6>  
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public class Utility { \PDd$syDA  
j 8*ZF  
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public Utility() +zXEYc  
{ ]8q3>  
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} ]f+ csB  
5` Te\H  
//线程睡眠 I2nF-JzD2a  
public static void sleep(int nSecond) 3vcO!6Z5  
{ t`*!w|}(1  
try{ ~\{^%~[48  
Thread.sleep(nSecond); ee%fqVQ8P  
} ~gB>) ]  
catch(Exception e) _ZY)M  
{ ?\C"YG69T  
e.printStackTrace (); ,'[<bP'%_  
} B<j'm0a>B  
} %K(<$!  
pw7[y^[Qg  
//日志 @u==x*{|  
public static void log(String sMsg) I%- " |]$  
{ _g1b{$  
System.err.println(sMsg);  r.4LU  
} !r#?C9Sq  
-S3MH1TZ  
$O9^SB  
public static void log(int sMsg) Neg,qOt  
{ !9Aaj<yxm  
System.err.println(sMsg); T&Lb<'f  
} ^i:`ZfA#
 
} (aD_zG=k5  
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/* TMYd47  
**TestMethod.java A&nU]R8S  
*/ gy&[?m6M=  
package NetFox; W5SJ^,d)J  
|V<h=D5W  
035rPT7-2-  
public class TestMethod { <.Nx[!'~&d  
G:zua`u[  
Me 5_4H&Sg  
public TestMethod() |SyMngIY  
{ ///xx/weblogic60b2_win.exe r*Yi1j/  
try{ 3B1cb[2y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); >JiltF7H0  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); sQMFpIrr  
SiteFileFetch fileFetch = new SiteFileFetch(bean); DGzw8|/(  
fileFetch.start(); m!<\WN6g  
} [B+W%g(c-  
catch(Exception e){e.printStackTrace ();} mEG#>Gg$  
4~B> 9<$e>  
NH+(?TN  
} 27;ci:5  
J~#;<e{\"  
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public static void main(String[] args) w8n|B?Sr  
{ )B[0JrcE  
new TestMethod(); P*cNh43U  
} ;[fw]P n  
} s`0QA!G{-  
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