http断点续传简单实现（java)

/* X=b]Whuv  
**SiteFileFetch.java @$d_JwI  
*/ g`zC0~D2  
package NetFox; qgLj^{  
import java.io.*; ]a=Bc~g91  
import java.net.*; p[gq^5WuC  
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public class SiteFileFetch extends Thread { u'EzYJ7  
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SiteInfoBean siteInfoBean = null; //文件信息Bean #_OrS/H  
long[] nStartPos; //开始位置 lw 9rf4RF  
long[] nEndPos; //结束位置 cY\"{o"C  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 i/WiSwh:  
long nFileLength; //文件长度 79
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boolean bFirst = true; //是否第一次取文件 +q4AK<y-  
boolean bStop = false; //停止标志 ~C2[5r{So  
File tmpFile; //文件下载的临时信息 -7l)m
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DataOutputStream output; //输出到文件的输出流 &8wluOs/5  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） J#& C&S 2  
public SiteFileFetch(SiteInfoBean bean) throws IOException '@+a]kCMev  
{ d#G H4+C  
siteInfoBean = bean; |yow(2(F@  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); e!~x-P5M`  
if(tmpFile.exists ()) }fKpih  
{ wN
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bFirst = false; T8rf+B/.L  
read_nPos(); r6eApKZ>f6  
} 0?nm`9v6  
else ,=kQJ|  
{ |F#L{=B  
nStartPos = new long[bean.getNSplitter()]; t{)J#8:g  
nEndPos = new long[bean.getNSplitter()]; CK+_T}+-  
} m`lsUN,  
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} KUqD<Jj?  
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public void run() ,d3
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{ (
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//获得文件长度 w_!]_6%{b  
//分割文件 Hh1OD?N)  
//实例FileSplitterFetch [m3k_;[  
//启动FileSplitterFetch线程 0Bpix|mq  
//等待子线程返回 6+[7UH~pm^  
try{ e7.!=R{6  
if(bFirst) ;MR(Ea
ep  
{ RGim):1e  
nFileLength = getFileSize();  "Aq-H g  
if(nFileLength == -1) P7GF"/  
{ o!+jPwEU  
System.err.println("File Length is not known!"); R\wG3Oxol  
} "xV9$m>
 
else if(nFileLength == -2) &N!;d E  
{ "ujt:4p@  
System.err.println("File is not access!"); |F 18j9  
} +wwK#ocw  
else -]h3s >
t  
{ ;tF7GjEp  
for(int i=0;i<nStartPos.length;i++) )0:@
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{ T;%ceLD  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); _%HyXd  
} 'j+J?Y^  
for(int i=0;i<nEndPos.length-1;i++) A"@C }f  
{ ,4wZ/r> d  
nEndPos = nStartPos[i+1]; Dab1^H!KT  
} OW12m{  
nEndPos[nEndPos.length-1] = nFileLength; b}[W[J}`  
} vK?{Z^J][  
} .{1MM8 Q  
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//启动子线程 v5 yOh5  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; u&>o1!c*P  
for(int i=0;i<nStartPos.length;i++) huau(s0um  
{ {AY`\G  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), e>kw>%3bl9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), E30VKh |  
nStartPos,nEndPos,i); J!:ss  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Iz#h:O  
fileSplitterFetch.start(); J8x>vC  
} r$*p  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Pxj?W'|  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); VlVd"jW  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", WJ+<&6W8  
nEndPos = " + nFileLength);  R9->.eE  
// fileSplitterFetch[nPos.length-1].start(); j/R  
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;TK:D=p4  
//等待子线程结束 av1*i3  
//int count = 0; /EOtK|E  
//是否结束while循环 {qm(Z+wcmb  
boolean breakWhile = false; Cp_YIcnEJ  
 @GYM4T  
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while(!bStop) TWC^M{e  
{ 7ST[XLwt%}  
write_nPos(); TCSm#?[B  
Utility.sleep(500); u=I>DEe@c  
breakWhile = true; ]~z2s;J{/  
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for(int i=0;i<nStartPos.length;i++) ~mtL\!vaM  
{ 1_7}B4  
if(!fileSplitterFetch.bDownOver) 1@H3!V4  
{ _AQ :<0/#  
breakWhile = false; :CN,I!:  
break; AG#5_0]P~  
} =S-'
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} 6M"]p  
if(breakWhile) 6|05-x|  
break; i%M2(8&^Q  
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>sP-)ZeuU[  
//count++; 33\{S$p  
//if(count>4) @fp(uu  
// siteStop(); )jp#|#h  
} B_[^<2_  
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System.err.println("文件下载结束！"); S)GWr"m-  
} f4zd(J  
catch(Exception e){e.printStackTrace ();} JQ%`]=n(/  
} iuq-M?1  
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//获得文件长度 9[|Ql  
public long getFileSize() Pe/cwKCI  
{ un[Z$moN"  
int nFileLength = -1; #5T+P8  
try{ +"a .,-f!  
URL url = new URL(siteInfoBean.getSSiteURL()); ~)}npS;  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); D:llGdU#2  
httpConnection.setRequestProperty("User-Agent","NetFox"); j]6j!.1  
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int responseCode=httpConnection.getResponseCode(); "}|n;:r  
if(responseCode>=400) <UG}P \N  
{ `I<*R0Qe  
processErrorCode(responseCode); !E> *Mn  
return -2; //-2 represent access is error @3{'!#/  
} \{n]&IjA  

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String sHeader; oa+Rr&t'  
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j ij:}.d6  
for(int i=1;;i++) jR\T\r4  
{ ekfD+X  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); u9e A"\s  
//Utility.log(in.readLine());
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sHeader=httpConnection.getHeaderFieldKey(i); b IcLMG s  
if(sHeader!=null) zHr1FxD  
{ lx~!FLn  
if(sHeader.equals("Content-Length")) bxO8q57  
{ 2<yE3:VX  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); y&A*/J4P  
break; .8l\;/o|  
} ]xA;*b;|h  
} uU6+cDp  
else 7[:9vY  
break; c0u!V+V%  
} f>5{SoM  
} qr(SAIX"  
catch(IOException e){e.printStackTrace ();} <O>r e3s  
catch(Exception e){e.printStackTrace ();} Se*GR"Z+  
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Utility.log(nFileLength); }V?SedsY  
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return nFileLength; X<_(gg  
} I* \o  
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Q,Hw@w<1  
//保存下载信息（文件指针位置） +BM(0M+  
private void write_nPos() h{yqNl  
{ f5Zx:g  
try{ z![RC59S  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Ip( IGR"  
output.writeInt(nStartPos.length); S?*v p=  
for(int i=0;i<nStartPos.length;i++) -d6|D?}S  
{ H |Z9]+h)7  
// output.writeLong(nPos); L\5j"] }`  
output.writeLong(fileSplitterFetch.nStartPos); >.SU=HG;  
output.writeLong(fileSplitterFetch.nEndPos); 1/3Go97/qV  
} WtFv"$V  
output.close(); $Dd IY}  
} h2!We#  
catch(IOException e){e.printStackTrace ();} \Zqgr/.w/  
catch(Exception e){e.printStackTrace ();} kp[+Iun?  
} rcPP-+XW  
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//读取保存的下载信息（文件指针位置） ~9
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private void read_nPos() Y
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{ %:N6#;l M  
try{ vN-#Ej. u  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); iQZgs@  
int nCount = input.readInt(); Lcf =)GL  
nStartPos = new long[nCount]; 1[a;2xA~  
nEndPos = new long[nCount]; ,Zb]3  
for(int i=0;i<nStartPos.length;i++) *;(
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{ +%=Ao6/#  
nStartPos = input.readLong(); hJ>{`Tw  
nEndPos = input.readLong(); @/ wJW``;  
} T c4N\Cy  
input.close(); +y>D3I  
} eRD?O  
catch(IOException e){e.printStackTrace ();} A/,7%bB1  
catch(Exception e){e.printStackTrace ();} wZ,9~P7  
} c</d1xT  
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private void processErrorCode(int nErrorCode) amK?LDf]  
{ /<9VKMR_k  
System.err.println("Error Code : " + nErrorCode); :z56!qU  
} lq}=&)%C  
<K%qaf  
!,+p
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//停止文件下载 5v=%pQbY  
public void siteStop() @O5-w  
{ G7DEavtr  
bStop = true; .ZFs+8qU>  
for(int i=0;i<nStartPos.length;i++) l!<Nw8+U  
fileSplitterFetch.splitterStop(); E#`=xg  
{^1GHU  
=4"D8UaHr  
} wLPL9  
} F"#bCnS  
//负责部分文件的抓取 [bIdhG  
**FileSplitterFetch.java M])Y|}wv8  
*/ `$j
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package NetFox; VJS|H!CH  
:seo0w]  
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import java.io.*; 13I 7ah  
import java.net.*; {j+w|;dZF  
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# nwEF QA  
public class FileSplitterFetch extends Thread { **d3uc4y  
lV:R8^d  
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String sURL; //File URL }xn\.M:ic  
long nStartPos; //File Snippet Start Position "D'A7DA  
long nEndPos; //File Snippet End Position K3$83%E  
int nThreadID; //Thread's ID p3`'i  
boolean bDownOver = false; //Downing is over P}KN*Hn.  
boolean bStop = false; //Stop identical 8 qt,sU  
FileAccessI fileAccessI = null; //File Access interface iv2did4  
"GEJ9_a[  
h!?7I=p~#  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 9Ruj_U  
{ ;"hED:z6%  
this.sURL = sURL; ZMy0iQ@  
this.nStartPos = nStart; d_BECx<\  
this.nEndPos = nEnd; Kgbgp mW  
nThreadID = id; +N:K V}K  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 3*"
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} ^\Nsx)Y;  
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public void run() Zj99]4?9  
{ 8 sZ~3  
while(nStartPos < nEndPos && !bStop) hn#i,XnY  
{ ya0L8`q  
s"#JBw\7  
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try{ w,cfSF;=tC  
URL url = new URL(sURL); .8S6;xnkC  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); E%t_17,=j  
httpConnection.setRequestProperty("User-Agent","NetFox"); im_WTZz2P  
String sProperty = "bytes="+nStartPos+"-"; MU4/arXy  
httpConnection.setRequestProperty("RANGE",sProperty); (|I:
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Utility.log(sProperty); t8DySFT  
 iUJqAi1o  
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InputStream input = httpConnection.getInputStream(); Q3vC^}Dmr  
//logResponseHead(httpConnection); 4d#w}  
L}*:,&Y/  
{O9CYP:  
byte[] b = new byte[1024]; 9E4H`[EQ  
int nRead; i[/g&fx  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 3zo]*6p0  
{ >!MOgLO3  
nStartPos += fileAccessI.write(b,0,nRead); ?2zVWZ  
//if(nThreadID == 1) /_5I}{  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _]a8lr+_-  
} 3JVENn9  
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Utility.log("Thread " + nThreadID + " is over!"); =T;>$&qs  
bDownOver = true; D0Yl?LU3  
//nPos = fileAccessI.write (b,0,nRead); 5@ecZ2`)+h  
} mD{<Lp=  
catch(Exception e){e.printStackTrace ();} DvCs 5  
} #5-5N5-1  
} u@tJu'X  
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! /;@kXN
 
//打印回应的头信息 Fk@A;22N  
public void logResponseHead(HttpURLConnection con) bmgK6OyVR  
{ /. GHR  
for(int i=1;;i++) FtXd6)_S  
{ }CnqJ@>C5  
String header=con.getHeaderFieldKey(i); 23 j{bK  
if(header!=null) SQhk)S  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); wDswK "T  
Utility.log(header+" : "+con.getHeaderField(header)); T+ey>[  
else
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break; WPi^;c8  
} YUU|!A8x  
} NWWa
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public void splitterStop() @RGVcfCG)  
{ Y?W"@awE"\  
bStop = true; PPSf8-MLW  
} 9v>BP`Mg  
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@ c,KK~{  
} Bf33%I~  
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/* Rp$t;=SMD  
**FileAccess.java M
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*//文件访问(定位，写) VN`T:!&  
package NetFox; X_GR{z%  
import java.io.*; "9,z"k  
/cHd&i,>  
t)P5bQ+$u9  
public class FileAccessI implements Serializable{  SbQ Ri  
M:x?I_JG8  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 'zCJ
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RandomAccessFile oSavedFile; r2A%.bL#  
long nPos; ,CqJ((  
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public FileAccessI() throws IOException .J:04t1  
{ kXimJL_<g  
this("",0); e+jp03m\W  
} ~wG.'d]  
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public FileAccessI(String sName,long nPos) throws IOException i(R&Q;{E^  
{ l9"4"+?j<  
oSavedFile = new RandomAccessFile(sName,"rw"); ,4W|e!  
this.nPos = nPos; w#.Tp-AZ;\  
oSavedFile.seek(nPos); \pI)tnu6'U  
} .BN~9w  
N!Dc\d=8q]  
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public synchronized int write(byte[] b,int nStart,int nLen) W:D'k^u  
{ ^9*FYV  
int n = -1; ~XAtt\WS  
try{ *V+6409m  
oSavedFile.write(b,nStart,nLen); _/;k;$gDp  
n = nLen; :Awnj!KNCc  
} Vj?{T(K1[  
catch(IOException e) M`IiK+IoU  
{ Trd/\tX#v&  
e.printStackTrace (); ngF5ywIG  
} sute%6yM  
O%?TxzX;  
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return n; !u~h.DrvZ  
} G8xM]'y  
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} &atT7m  
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/* {Ic~}>w  
**SiteInfoBean.java KV1zx(WI  
*/ ly`p)6#R=  
package NetFox; C =fs[  
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public class SiteInfoBean { 'Okitq+O  
_4qP0LCa  
A*l(0`aWq  
private String sSiteURL; //Site's URL v_Om3i9$E  
private String sFilePath; //Saved File's Path +zodkB~)  
private String sFileName; //Saved File's Name K"'W4bO#7  
private int nSplitter; //Count of Splited Downloading File &8!*u3  
c%1<O!c  
*&p`8:  
public SiteInfoBean() g
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{//nSplitter的缺省值为5 `P1jg$(eA  
//default value of nSplitter is 5 2yqm$i9C  
this("","","",5); AWlR" p2  
} >XzCHtEP  
v4]7"7GuW  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) V0hC[Ilr  
{ "0Xa?z8"  
sSiteURL= sURL; Bi?.w5  
sFilePath = sPath; cU}j Whu  
sFileName = sName; ?DP]#9/4  
this.nSplitter = nSpiltter; ;{b 1'  
$ijWwrh  
C6Qnn@waYb  
} \ZdV|23  
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*O') {(  
public String getSSiteURL() Xh==F:  
{ M$O}roOa  
return sSiteURL; c
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} Hbogi1!al|  
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public void setSSiteURL(String value) [\N,ow,n  
{ b 62 o  
sSiteURL = value; .<JD'%?"  
} j^A0[:2  
(1e;7sNG@  
+ >o/Ob  
public String getSFilePath() e-<fkU9^W  
{ q4_&C&7  
return sFilePath; b~\gV_Z  
} zo66=vE!  
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public void setSFilePath(String value) B.2F\ub g  
{ wc-H`S|@  
sFilePath = value; iN%\wkx*N  
} x#yL&+'?Mj  
]9z{ 95  
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public String getSFileName() $^R[t;  
{ x9r5 ;5TI  
return sFileName; ,6rg00wGE  
} *au&ODa  
=8OPjcX.V  
7NG^X"N{Ul  
public void setSFileName(String value) H?8uy_Sc  
{ "Yw-1h`fR  
sFileName = value; kE QT[Lo  
} )W9$_<Z  
@ -pi  
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public int getNSplitter() p1t9s N,  
{ L+Q"z*W  
return nSplitter; +=I_3Wtth  
} ~X;r}l=k<  
+) 2c\1  
yBO88rfh
>  
public void setNSplitter(int nCount) A S;ra,x  
{ q[]EVs0$ew  
nSplitter = nCount; Q1V4bmM  
} kK!An!9C  
} :,<e  
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/* G`E%uyjG$j  
**Utility.java *g&[?y`UC  
*/ }8 A]  
package NetFox; 88Yp0T<1  
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public class Utility { z<_{m4I;  
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public Utility() H@2JL.(k  
{ /Kb7#uq  
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} M=n!tVlCV  
s5FyP"V  
//线程睡眠 )ARfI)<1b  
public static void sleep(int nSecond) l i}4d+  
{ 7QL>f5Q
 
try{ kV"';a  
Thread.sleep(nSecond); ch,<4E/c[R  
} c:"*MM RC  
catch(Exception e) k!O#6
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{ e#IED!U  
e.printStackTrace (); t6_6Bl:  
} ?m#X";^V  
} LKY4rY!|@d  
MdT'xYomzQ  
//日志 tDFN *#(  
public static void log(String sMsg) 2Xk(3J!!'a  
{ F>&Q5Kl R  
System.err.println(sMsg); [>&Nhn0iY  
} '#[U7(lIQ  
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public static void log(int sMsg) 2H fP$.  
{ wG2lCv`
d  
System.err.println(sMsg); ON _uu]=  
} G\tTwX4  
} 
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^Qz8`1`;Z  
/* vjaIFyj  
**TestMethod.java GEfX,9LF&  
*/ bmna*!l^M  
package NetFox; 3(%hHM7DM  
=K{$?%"  
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public class TestMethod { -QCo]:cp  
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public TestMethod() j#y_#  
{ ///xx/weblogic60b2_win.exe z^I"{eT8  
try{ Qpiv,n  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); kvv-f9/-  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); z~+_sTu  
SiteFileFetch fileFetch = new SiteFileFetch(bean); r]Da4G^  
fileFetch.start(); G+AD &EHV  
} j2deb`GD  
catch(Exception e){e.printStackTrace ();} 6'395x_.\  
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0}hN/2}&  
} fm87?RgXD  
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public static void main(String[] args) bmhvC9  
{ D|9C|
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new TestMethod(); ,%mTKOs  
} RfDIwkpp  
} =|S8.|r+  
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