http断点续传简单实现（java)

/* fQ+\;iAU  
**SiteFileFetch.java .R5y:O  
*/ R^*K6Ad  
package NetFox; ow6*Xr8eQ  
import java.io.*;
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import java.net.*; ~GJN@ka4%  
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public class SiteFileFetch extends Thread { >^$2f&z  
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!:CJPM6j3  
SiteInfoBean siteInfoBean = null; //文件信息Bean la <npX  
long[] nStartPos; //开始位置 06*rWu9P3  
long[] nEndPos; //结束位置 R}:KE&tq  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Vp}
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long nFileLength; //文件长度 a%BeqSZh  
boolean bFirst = true; //是否第一次取文件 pV(lhDNoQ  
boolean bStop = false; //停止标志 }-@4vl x$  
File tmpFile; //文件下载的临时信息 ' GG=Ebt  
DataOutputStream output; //输出到文件的输出流 Ad$n4Ze  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） gRJfX%*F  
public SiteFileFetch(SiteInfoBean bean) throws IOException |o<8}Nja6  
{ tMp=-"  
siteInfoBean = bean; RDM`9&V!jp  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); J*fBZ.NO  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ILw
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if(tmpFile.exists ()) otJ!UfpR8  
{ ($nrqAv4  
bFirst = false; ~8T(>!hE1h  
read_nPos(); !yOeW0/2[  
} SC &~s
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else jJZgK$5+  
{ C'A]i5  
nStartPos = new long[bean.getNSplitter()]; 1"#*)MF  
nEndPos = new long[bean.getNSplitter()]; *e#<n_%R  
} 1w(JEqY3h:  
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} ]aryV?!6  
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public void run() 8>WVodv  
{ V DS23Bo  
//获得文件长度 )yK[Zb[  
//分割文件 TXXy\$  
//实例FileSplitterFetch 4Kwh?8.  
//启动FileSplitterFetch线程 WQNE2Q  
//等待子线程返回 9@ 16w  
try{ 9Z5D\yv?H  
if(bFirst) 3q:n'PC)C  
{ 3]&o*Ib1`_  
nFileLength = getFileSize(); evA/+F,&  
if(nFileLength == -1) qFQ8  
{ NS)}6OI3~"  
System.err.println("File Length is not known!"); L6Wt3U`l  
} e
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else if(nFileLength == -2) `#-P[q<v-  
{ sbj(|1,ac  
System.err.println("File is not access!"); 2F#q I1  
} bI.t<;  
else ^D`v3d  
{ W1B)]IHc  
for(int i=0;i<nStartPos.length;i++) 9[c%J*r
 
{ 6r:?;j~l  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 2`GE  
} :u8
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for(int i=0;i<nEndPos.length-1;i++) 7!y5 SX8C  
{ dC\ZjZZ  
nEndPos = nStartPos[i+1]; u]+~VT1C,3  
} .\0isO  
nEndPos[nEndPos.length-1] = nFileLength; S [h];eM  
} %1 vsN-O}8  
} UO*Ymj 1  
[%Bf< J<  
bwM@/g%DL  
//启动子线程 !o=U19)  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; <s5qy-
 
for(int i=0;i<nStartPos.length;i++) 5]I|DHmu  
{ zk*c)
s  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ##Q/I|  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), [.hyZ}B  
nStartPos,nEndPos,i); -Y Bd, k3  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'bld,Do6  
fileSplitterFetch.start(); *KY=\ %D  
} hQ6a~?f  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .h&k jD  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ;$Y4xM`=m  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ")O`mXg-  
nEndPos = " + nFileLength); VhjM>(  
// fileSplitterFetch[nPos.length-1].start(); joKIrS0y  
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~8"8w(CG*I  
//等待子线程结束 
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//int count = 0; \I"Z2N>^z  
//是否结束while循环 ]?x: Qm'yo  
boolean breakWhile = false; \0lnxLA  
*BuUHjTv  
@/ZF` :  
while(!bStop) g;$Xq)Dd  
{ ;S0Kh"A  
write_nPos(); LK6; ?m  
Utility.sleep(500); A;\7|'4  
breakWhile = true; Q#h 9n]5  
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for(int i=0;i<nStartPos.length;i++) 2C{H$ A,pW  
{ U9D!GKVp  
if(!fileSplitterFetch.bDownOver) ?(*t@ {k  
{ E*L iM5+I  
breakWhile = false; "&+"@<  
break; R4ht6Vm3g)  
} n,$IfC"  
} [=B$5%A  
if(breakWhile) lWBb4 !l  
break; pV4Whq$  
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//count++; w =.Fj  
//if(count>4) [mEql,x3  
// siteStop(); U=hlu  
} %IC73?  
=
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System.err.println("文件下载结束！"); n,B,"\fw  
} "#(T  
catch(Exception e){e.printStackTrace ();} }y9mNT  
} ^Y-]*8;]  
T\w?$ s  
[]a[v%PkG  
//获得文件长度 Ag F,aZU  
public long getFileSize() JQ4{` =,b  
{ gTA%uRBa  
int nFileLength = -1; 3%.#}O,(  
try{ It2" x;  
URL url = new URL(siteInfoBean.getSSiteURL()); )M__ t5L  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); \:'%9 x  
httpConnection.setRequestProperty("User-Agent","NetFox"); dCj,b$  
yHxosxd<*  
M33_ja+L  
int responseCode=httpConnection.getResponseCode(); /-bO!RTwf  
if(responseCode>=400) aW!@f[%~F  
{ 
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processErrorCode(responseCode); dt2$`X18  
return -2; //-2 represent access is error wdUBg*X8  
} WVY\&|)$  
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String sHeader; `,Ph/oM  
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for(int i=1;;i++) x3PD1JUf  
{ YZ%Hu)  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); P-ri=E}>  
//Utility.log(in.readLine()); TDd{.8qf  
sHeader=httpConnection.getHeaderFieldKey(i); 6xD#?  
if(sHeader!=null) hEh}PX:  
{ w`q%#qRk  
if(sHeader.equals("Content-Length")) ew"v{=X  
{ e9Nk3Sj]  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); l x,"EOP  
break; fu90]upz~  
} ^h{)Gf,+\  
} q$aaA`E%  
else 4wrk2x[  
break; bQ~j=\[r  
} sg+uBCGB  
} }1>[  
catch(IOException e){e.printStackTrace ();} 2(/g}  
catch(Exception e){e.printStackTrace ();} i+gQE!  

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Utility.log(nFileLength); ;]_o4e6\p  
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return nFileLength; 5Kkdo!z  
} V*W;OiE_3  
3>Y6)  
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//保存下载信息（文件指针位置） CZ nOui  
private void write_nPos() $z+8<?YD  
{ cK 06]-Y  
try{ =b/L?dR.-  
output = new DataOutputStream(new FileOutputStream(tmpFile)); -&<Whhs.@  
output.writeInt(nStartPos.length); ^a#X9  
for(int i=0;i<nStartPos.length;i++) Offu9`DiZ  
{ Me=CSQqf<  
// output.writeLong(nPos); Br`IW  
output.writeLong(fileSplitterFetch.nStartPos); tO0!5#-VR  
output.writeLong(fileSplitterFetch.nEndPos); [H=)  
} 4q<=K=F  
output.close(); P3oI2\)*i  
} R+Y4|  
catch(IOException e){e.printStackTrace ();} qbv#I;  
catch(Exception e){e.printStackTrace ();} x:nKfY5  
} vsa92c@T  
+Z85HY{  
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//读取保存的下载信息（文件指针位置） 9]e V?yoA8  
private void read_nPos() $ aUo aI  
{ 48Mp
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try{ X,LD   
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ,mj@sC>  
int nCount = input.readInt(); ~q~MoN<R  
nStartPos = new long[nCount]; w+N> h;j  
nEndPos = new long[nCount]; aXL{TD:]  
for(int i=0;i<nStartPos.length;i++) {RF-sqce  
{ &B|D;|7H  
nStartPos = input.readLong(); zD<or&6  
nEndPos = input.readLong(); )HvnoUO0  
} d'Zqaaf k%  
input.close(); '7oA< R  
} ,u/aT5\_  
catch(IOException e){e.printStackTrace ();} xKFn.qFr  
catch(Exception e){e.printStackTrace ();} 7PkJ-JBA  
} Y*!qG  
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private void processErrorCode(int nErrorCode) EI^06q4x  
{ 3mOtW%Hl  
System.err.println("Error Code : " + nErrorCode); 3YZs+d.;ib  
} pZeE61c/  
k68F-e[i^  
.B\5OI,]  
//停止文件下载 FHC\?Cg  
public void siteStop() $H-!j%hV  
{ (`:O~>[N  
bStop = true; J.8IwN1E  
for(int i=0;i<nStartPos.length;i++) W16,Alf:  
fileSplitterFetch.splitterStop(); 4fKC6UR  
q=#} yEG  
RoyPrO [3  
} m'f,_ \'  
} d20gf:@BM  
//负责部分文件的抓取 k70|'*Kh  
**FileSplitterFetch.java B` k\EL'  
*/ HB7;0yt`:  
package NetFox; 1n@8Kv  
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import java.io.*; yfm^?G|sW  
import java.net.*; 8)4P Ll  
o";Z$tAJkC  
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public class FileSplitterFetch extends Thread { rf$X>M=G  
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String sURL; //File URL 4!LCR}K  
long nStartPos; //File Snippet Start Position 7R\oj
8[  
long nEndPos; //File Snippet End Position qcN'e.A  
int nThreadID; //Thread's ID IEzaK  
boolean bDownOver = false; //Downing is over AU$Uxwz4  
boolean bStop = false; //Stop identical _~T!9  
FileAccessI fileAccessI = null; //File Access interface 1u6^z  
_-#'j2  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException vo#UtN:q  
{ +mp@b942*  
this.sURL = sURL; <-u8~N@43W  
this.nStartPos = nStart; X0n~-m"m  
this.nEndPos = nEnd; QI3Nc8t_2  
nThreadID = id; 9J?wO9rI  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 iURk=*Z=  
} Ck!VV2U#  
+*hm-lv?  
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public void run() /=gOa\k|p  
{ 2^l[(N  
while(nStartPos < nEndPos && !bStop) =hMY2D  
{ R<=zCE`:  
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try{ Yx>"bv  
URL url = new URL(sURL); A$a1(8H  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); n2fbp\I  
httpConnection.setRequestProperty("User-Agent","NetFox"); <Ce2r"U1e  
String sProperty = "bytes="+nStartPos+"-"; $]A/ o(  
httpConnection.setRequestProperty("RANGE",sProperty); uECsh2Uin  
Utility.log(sProperty); Gqy,u3lE  
"1HRLci  
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InputStream input = httpConnection.getInputStream(); :.45u}[  
//logResponseHead(httpConnection);  z~>pVs
  
<,>P0tY}  
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byte[] b = new byte[1024]; 6MxKl D7kl  
int nRead; A21N|$[  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Ed ,D8ND  
{ :G<E^<M\)^  
nStartPos += fileAccessI.write(b,0,nRead); mI>,.&eo  
//if(nThreadID == 1) j7)Ao*WN  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 91xB9k1zO  
} U\sHx68  
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[l8jRT=R  
Utility.log("Thread " + nThreadID + " is over!"); xQ'2BA
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bDownOver = true;  &CG*)bE  
//nPos = fileAccessI.write (b,0,nRead); |a#f\  
} !eUDi(  
catch(Exception e){e.printStackTrace ();} w&%~3Cz.  
} FSRj4e1y1  
} '_$uW&{NI  
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//打印回应的头信息
+|
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public void logResponseHead(HttpURLConnection con) E=#0I]v[  
{ Ck/F9(  
for(int i=1;;i++) |#*'H*W  
{ %
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String header=con.getHeaderFieldKey(i); nQ/E5y  
if(header!=null) jH6&q
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); E.U
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Utility.log(header+" : "+con.getHeaderField(header)); eBJUv]o %  
else ;-Jb1"5  
break; c?%(DpE  
} =dx1/4bZl|  
} p3}?fej&|  
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2 6>ZW4Z  
public void splitterStop() UYz0PSV=.  
{ 41_SRh7N  
bStop = true; LB.co4  
} Rd>B0;4  
+nT'I!//  
"jaJr5Wv=y  
} \fjMc }'  
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/* wm+})SOX9  
**FileAccess.java ys#i@  
*//文件访问(定位，写) 8O"U 0  
package NetFox; QL$S4 J"  
import java.io.*; (4%YHS8  
:#lIx%l  
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public class FileAccessI implements Serializable{ B7Tk4q\;Q  
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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 tM#lFmdd\P  
RandomAccessFile oSavedFile;
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long nPos; 3.)b4T  
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public FileAccessI() throws IOException nL?oTze*p  
{ ;2m<CSv!D  
this("",0); U/NBFc:[y:  
} u(!&:A9JFd  
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public FileAccessI(String sName,long nPos) throws IOException v0Ir#B,[H  
{ y4Er@8I`  
oSavedFile = new RandomAccessFile(sName,"rw"); i
7LJ&g/)  
this.nPos = nPos; 9RwawTM  
oSavedFile.seek(nPos); <A.W 8b7D  
} -ti{6:H8  
5%}wV,Y  
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public synchronized int write(byte[] b,int nStart,int nLen) &Z^l=YH,  
{ |/ }\6L]  
int n = -1; Xq4|uuS-O  
try{ ]/cd;u  
oSavedFile.write(b,nStart,nLen); jn.C|9/mj  
n = nLen; _3Cn{{ A0  
} U,Mx@KdV  
catch(IOException e) D?M!ra  
{ xE-7P|2  
e.printStackTrace (); `O6:t\d@  
} k6Cn"2q <  
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return n; KL'zXkS  
} <:|3rfm#  
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} 2ij# H ;  
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/* ~}DQT>7$  
**SiteInfoBean.java >`jU`bR@  
*/ T5O _LCIws  
package NetFox; MEiRj]t  
EC6k{y}bA  
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public class SiteInfoBean { 8p1ziz`4>$  
@uH#qg7  
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private String sSiteURL; //Site's URL ~svO*o Wa  
private String sFilePath; //Saved File's Path
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private String sFileName; //Saved File's Name gX5&d\y  
private int nSplitter; //Count of Splited Downloading File H0"=Vs,n  
"gW7<ilw   
 8%RI7Mg  
public SiteInfoBean() D,ly#Nn  
{//nSplitter的缺省值为5 OVk~N)  
//default value of nSplitter is 5 uENdI2EY8y  
this("","","",5);  StYzGJ  
} VK3it3FI>3  
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c3 &m9zC  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ;pRcVL_4  
{ TQ9D68 ,  
sSiteURL= sURL; eXl=i-'  
sFilePath = sPath; La[K!u\B  
sFileName = sName; UF__O.l__  
this.nSplitter = nSpiltter; qO`qJ/  
+7}iu/B!9  
h?,\(KjP#  
} hF&}lPVtv  
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public String getSSiteURL() _2vd`k  
{ H'J|U|  
return sSiteURL; %1:chvS  
} 99 wc  
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public void setSSiteURL(String value) s* jfMY  
{ ]qw0V   
sSiteURL = value; Ov9Q?8KzM  
} _ :^7a3I  
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public String getSFilePath() 8)0L2KL'  
{ EA{U!b]cU  
return sFilePath; v+1i=s2$  
} %3Bpn=k>  
v
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public void setSFilePath(String value) $;D* n'8Fx  
{ ;8B.;%qkL  
sFilePath = value; CHaE;olo  
} 3 EYiQ`  
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public String getSFileName() >[*4Tjg  
{ %(LvE}[RJ  
return sFileName; Ygkv7>?,  
} o7xgRSz\  
b7h+?!H]R  
)fh0&Y; R  
public void setSFileName(String value) et$uP  
{ qSiWnN8D t  
sFileName = value; H}b\`N[nr  
} -fIc
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public int getNSplitter() fnH3CE  
{ xRX>|S  
return nSplitter; g*-2* \  
} N\R=cwk  
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kR6A3?[  
public void setNSplitter(int nCount) F!8=FTb  
{ Q~ 0Dfow?  
nSplitter = nCount; 68x}w Ae  
} MTmO>V&O  
} qa!RH]B3  
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/* d
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**Utility.java W(&6  
*/ 9qH[o?]
 
package NetFox; 3ps,uozj  
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public class Utility { #@_1f
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public Utility() D<nxr~pQ  
{ !A[S6-18%-  
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} %ejeyc  
3Xdn62[&  
//线程睡眠 $pFk"]=  
public static void sleep(int nSecond) f9'] jJ+  
{ 6q%ed UED  
try{ }aZrou3E  
Thread.sleep(nSecond); sb'p-Mj  
} _pSIJ3O  
catch(Exception e) FDq{M?6i  
{ (2%>jg0M  
e.printStackTrace (); c)3O/`  
} ahp1!=Z-=  
} u33zceE8  
UB&2f>  
//日志 :QKb#4/8;  
public static void log(String sMsg) j)6G7T|  
{ 7!- \L7<  
System.err.println(sMsg); $-w5o`e  
} eU~?p|Np
 
ve%l({  
/c^e&D  
public static void log(int sMsg) T~:_}J  
{ GYqJ!,  
System.err.println(sMsg); cQ,9Rnfl,  
} ;o >WXw  
} @ta?&Qf)  
6z]`7`G  
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/* s]bPV,"p  
**TestMethod.java AP ;
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*/ ~R{8.!: >  
package NetFox; M c@GH  
 h,hL?imD  
N ^f}ui i  
public class TestMethod { cUC17z2D  

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`5<1EGJsD  
public TestMethod() IQoH@l&Xk  
{ ///xx/weblogic60b2_win.exe sU*3\  
try{ UKYupLu5  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ;/aB)JZ5=  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); CK Mv7  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Z^+a*^w~{  
fileFetch.start(); SW=aHM  
} *2#FRA#q  
catch(Exception e){e.printStackTrace ();} P#F_>GB  
q]+)c2M  
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} <O bHf`Q  
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public static void main(String[] args) 9;pzzZ  
{ ^Yr|K  
new TestMethod(); IrUi Eq  
} {DS\!0T-X  
} c&A]p
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