http断点续传简单实现（java)

/* *mM+(]8US  
**SiteFileFetch.java qO<'_7TN[  
*/ xy%lp{  
package NetFox; ua['rOnU  
import java.io.*; dQ8}mH!  
import java.net.*; {.N" 6P  
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public class SiteFileFetch extends Thread { N[j7^q7Xt  
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SiteInfoBean siteInfoBean = null; //文件信息Bean yD`{9'L -  
long[] nStartPos; //开始位置 >?,arER  
long[] nEndPos; //结束位置 v UAYYe  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 4[]R?lL  
long nFileLength; //文件长度 U4_<  
boolean bFirst = true; //是否第一次取文件 YZCPS6PuE  
boolean bStop = false; //停止标志 O,_2djd  
File tmpFile; //文件下载的临时信息 NA`3  
DataOutputStream output; //输出到文件的输出流 %8kbX  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） x7J|  
public SiteFileFetch(SiteInfoBean bean) throws IOException rbnu:+!  
{ rG"}CX`]:  
siteInfoBean = bean; aW3yl}`{  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Osb"$8im  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); R0fZ9_d7}  
if(tmpFile.exists ()) fV3!x,H  
{ AAsl)  
bFirst = false; H{x}gBQ  
read_nPos(); unmuY^+<  
} l%"eQ  
else `}F=Z
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{ twx8TQ9  
nStartPos = new long[bean.getNSplitter()]; J-fU,*Bk  
nEndPos = new long[bean.getNSplitter()]; c7IgndVAV  
} sHe:h XG'  
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} Jug1Va<^c  
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public void run() cW),Y|8  
{  !+IxPn  
//获得文件长度 c?d+>5"VX  
//分割文件 4i[3|hv'  
//实例FileSplitterFetch {R[lsdH(X  
//启动FileSplitterFetch线程 0-g,C=L  
//等待子线程返回 K+H?,I  
try{ Z>a_vC  
if(bFirst) b]mRn{r?  
{ DB_ x  
nFileLength = getFileSize(); kT UQ8U  
if(nFileLength == -1) 9U58#  
{ C^r3r6  
System.err.println("File Length is not known!"); +U^dllL7  
} ap\2={u^|  
else if(nFileLength == -2) 2?ZHWS>U  
{ lw?
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System.err.println("File is not access!"); gsc*![N  
} /w!b2KwV  
else @?K(+BGi  
{ >}<:5gZtA  
for(int i=0;i<nStartPos.length;i++) v>g1\yIw  
{ XFmnZpqXH  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); AY0o0\6cw  
} "[H9)aAj7  
for(int i=0;i<nEndPos.length-1;i++) sb(,w  
{ [_qBp:_j?s  
nEndPos = nStartPos[i+1];
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} {C*mn!u  
nEndPos[nEndPos.length-1] = nFileLength; (7}v}3/  
} ms ;RJT2O'  
} 3Du&KZ  
"S[VtuxPCU  
"SyyOD )WA  
//启动子线程 lyZof_/*  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; g@nk0lQewj  
for(int i=0;i<nStartPos.length;i++) + 7E6U*  
{ WLNkO^zb  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), +zs;>'Sf  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), SNff  
nStartPos,nEndPos,i); Y!o@"Ct  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 2Pi}<pG~
 
fileSplitterFetch.start(); 5jy>)WqK  
} MH"c=mL:  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), I|9e4EX{y  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); l},px  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", sj. eJX"z  
nEndPos = " + nFileLength); Um15@p;  
// fileSplitterFetch[nPos.length-1].start(); vn0XXuquzC  
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m98k/w_  
//等待子线程结束 X/i8$yqv  
//int count = 0; :n'QNGj  
//是否结束while循环 ,)GCg@7B  
boolean breakWhile = false; gNLjk4H,S[  
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while(!bStop) uVu`TgbZ  
{ ]pb;q(?^  
write_nPos(); [rPW@|^5  
Utility.sleep(500); <`|}bt  
breakWhile = true; K~,,xsy,G&  
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for(int i=0;i<nStartPos.length;i++) W .Hv2r3  
{ l*'jqR')h^  
if(!fileSplitterFetch.bDownOver) aQFYSl  
{ MQ\:/]a  
breakWhile = false; 2E2J=Do  
break; "!Mu5Ga  
} uaJ5'*  
} 8CA4gnh  
if(breakWhile) #wM0p:<  
break; NZeIqhj  
}(M<sEK~  
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//count++; %7 J  
//if(count>4) '`[nt25N  
// siteStop(); Fl*@@jQ8cV  
} fU)hn  
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System.err.println("文件下载结束！"); [.<vISRir  
} zy$hDy0  
catch(Exception e){e.printStackTrace ();} )\VUAD%~e7  
} wM!QU{Lz  
A|Y\Y}  
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//获得文件长度 3\mFK$#sr  
public long getFileSize() gs'bv#4yd  
{ @4$F%[g h  
int nFileLength = -1; OIewG5O  
try{ z+-k4  
URL url = new URL(siteInfoBean.getSSiteURL()); rKJ%/7m  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Uut,cQ". d  
httpConnection.setRequestProperty("User-Agent","NetFox"); TF=S \ Q  
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int responseCode=httpConnection.getResponseCode(); X% _~9'#%  
if(responseCode>=400) 8<.KWr  
{ 5>A3;P  
processErrorCode(responseCode); iNQk{n  
return -2; //-2 represent access is error ix!u#7  
} 1Kc*MS  
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String sHeader; h Qu9ux  
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for(int i=1;;i++) aL=VNZ!Pqc  
{ a-QHm;_S  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); o@pM??&x  
//Utility.log(in.readLine()); }#E4t3  
sHeader=httpConnection.getHeaderFieldKey(i); u5R^++  
if(sHeader!=null) JHO9d:{-  
{ 2d3wQ)2  
if(sHeader.equals("Content-Length")) " *Ni/p$I  
{ 8d$~wh  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); *$l8H[  
break; b<5:7C9z  
} Vn8Qsf1f  
} #4cuNX5m%  
else 8u+ (+25  
break; `H+Eo<U  
} PL8akA#  
} 0IA '8_K  
catch(IOException e){e.printStackTrace ();} v<2+y
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catch(Exception e){e.printStackTrace ();} o9eK7*D  
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Utility.log(nFileLength); R9#Z=f,  
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return nFileLength; Rwy:.)7B$q  
} HE(U0<9c  
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//保存下载信息（文件指针位置） >eRbasshEI  
private void write_nPos() %pg*oX1VK6  
{ sPZa|AKHb  
try{ E RMh% C  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ;G\rhk  
output.writeInt(nStartPos.length); \h0e09& I  
for(int i=0;i<nStartPos.length;i++) A6UtpyS*'  
{ )
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// output.writeLong(nPos); |x kixf4zz  
output.writeLong(fileSplitterFetch.nStartPos); vMC;5r6*d  
output.writeLong(fileSplitterFetch.nEndPos); &
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} K1+,y1c  
output.close(); m=}kGzIY4  
} T%]: tDa  
catch(IOException e){e.printStackTrace ();} z$YOV"N  
catch(Exception e){e.printStackTrace ();} RyM2CQg[  
} igo7F@_,  
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//读取保存的下载信息（文件指针位置） 8;Pdd1GyUL  
private void read_nPos() (ZI&'"H  
{ cdGl[dQ/  
try{ 0 /H1INve  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); mV4} -  
int nCount = input.readInt(); W%$p,^@S5  
nStartPos = new long[nCount]; QR8F'7S  
nEndPos = new long[nCount]; d5],O48A  
for(int i=0;i<nStartPos.length;i++) Fvv6<
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{ XSD7~X/:  
nStartPos = input.readLong(); Xg%zE  
nEndPos = input.readLong(); [%h^qJ  
} }5S2v+zE  
input.close(); jgO{DNe(=  
} 67sb D<r  
catch(IOException e){e.printStackTrace ();} )1]C%)zn  
catch(Exception e){e.printStackTrace ();} Q,DumOq  
} t)v#y!Ci"  
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private void processErrorCode(int nErrorCode) Jq; }q63:  
{ /y-P)3_  
System.err.println("Error Code : " + nErrorCode); /JfXK$`  
} k1cBMDSokO  
>:Oo[{)  
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//停止文件下载 M1g|m|H7  
public void siteStop() --/ .  
{ P]x@h  
bStop = true; cCj3,s/p  
for(int i=0;i<nStartPos.length;i++) 4u&l@BUr  
fileSplitterFetch.splitterStop(); d6n6= [*  
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} LS_QoS  
} |zUDu\MZ{  
//负责部分文件的抓取 xFvSQ`sp  
**FileSplitterFetch.java |Y99s)2&N  
*/  v EX <9  
package NetFox; ]pGr'T~Gj  
n/8fv~zU  
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import java.io.*; @Ab<I
  
import java.net.*; v>e4a/
  
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public class FileSplitterFetch extends Thread { E7D^6G&i  
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String sURL; //File URL ew
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long nStartPos; //File Snippet Start Position U?rfE(!  
long nEndPos; //File Snippet End Position @z,'IW74V  
int nThreadID; //Thread's ID 8~I>t9Q+  
boolean bDownOver = false; //Downing is over v0y7N_U5n  
boolean bStop = false; //Stop identical {B}0LJIpL  
FileAccessI fileAccessI = null; //File Access interface m|y]j4  
*X>rvAd3  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException +Rvj]vd}&  
{ -yAIrvO1q  
this.sURL = sURL; W"0#  
this.nStartPos = nStart;  OkQSqL  
this.nEndPos = nEnd; un\^Wmbw  
nThreadID = id; :I7MP  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 *V\kS  
} JxWHrsh[  
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public void run() }s|v-gRM{  
{ &]M<G)9  
while(nStartPos < nEndPos && !bStop) 5N6%N1  
{ W%wS+3Q/  
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.  
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try{ J'7Oxjlg  
URL url = new URL(sURL); 2<O hO ^  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ?+!KucTF  
httpConnection.setRequestProperty("User-Agent","NetFox"); W)"q9(T?%  
String sProperty = "bytes="+nStartPos+"-"; &sllM  
httpConnection.setRequestProperty("RANGE",sProperty); _]4cY%s  
Utility.log(sProperty); }I;W  
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InputStream input = httpConnection.getInputStream(); wx1uduT)  
//logResponseHead(httpConnection); emaNmpg  
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byte[] b = new byte[1024]; BAPi<U'D  
int nRead; "-Ns1A8  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) J>'o,"D  
{ vKW%l  
nStartPos += fileAccessI.write(b,0,nRead); ;L`'xFo>>  
//if(nThreadID == 1) #8RQ7|7b|  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); C

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} 'D-imLV<<  
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Utility.log("Thread " + nThreadID + " is over!"); uaGg8  
bDownOver = true; ^\CQWgY(  
//nPos = fileAccessI.write (b,0,nRead); (&B
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} |fA[s7)  
catch(Exception e){e.printStackTrace ();} MHbRG_zW  
} Rl)/[T  
} E*ic9Za8`h  
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//打印回应的头信息 (u*]&yk  
public void logResponseHead(HttpURLConnection con) rd"]$_P8O  
{ '5Y8 rv<  
for(int i=1;;i++) -py.YZ  
{ z#\Z
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String header=con.getHeaderFieldKey(i); toCN{[   
if(header!=null) G ;z2}Ei  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); %mq]M  
Utility.log(header+" : "+con.getHeaderField(header)); vSX 6~m  
else D"o>\Q  
break; ]EK"AuEz`  
} n% *u;iG  
} gC3{:MC-G  
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public void splitterStop() w&H ?;1  
{ ;?y?s'>t&  
bStop = true; $a-~ozr`C  
} `KL`^UqR  
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} =DtM.oQ>  
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/* E`X+fJx  
**FileAccess.java EfyF]cYL  
*//文件访问(定位，写) '*T7tl  
package NetFox; z><
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import java.io.*; E u@TCw8@  
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public class FileAccessI implements Serializable{ 5~sJ$5<,  
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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 eg}|%GG  
RandomAccessFile oSavedFile; 1xx-}AIH#  
long nPos; T.{I~_  
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public FileAccessI() throws IOException "16==
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{ sz)3 z  
this("",0); rdC(+2+Ay  
} Q!"Li  
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public FileAccessI(String sName,long nPos) throws IOException kL&^/([9  
{ v/^2K,[0>  
oSavedFile = new RandomAccessFile(sName,"rw"); y/PEm)=Tt  
this.nPos = nPos; n3)g{K^  
oSavedFile.seek(nPos); Z^h4%o-l{  
}
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public synchronized int write(byte[] b,int nStart,int nLen) fkx 9I m4  
{ 2L,e\]2Z  
int n = -1;
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try{ "+rX*~  
oSavedFile.write(b,nStart,nLen); H,uOshR  
n = nLen; O@ "6)/  
} jeJGxfii  
catch(IOException e) O<+C$J|  
{ _h.[I8xgYG  
e.printStackTrace (); eLt6Hg)s`9  
} 1LE8,Gm&  
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return n; SKYS6b  
} GWhb@K  
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} U%KoG-#  
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/* ucMl>G'!gX  
**SiteInfoBean.java uxR_(~8  
*/ e0hT  
package NetFox; q
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public class SiteInfoBean { lID5mg31  
[szwPNQ_  
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private String sSiteURL; //Site's URL 5[@4($q8  
private String sFilePath; //Saved File's Path .
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private String sFileName; //Saved File's Name hZ%Ie%~n  
private int nSplitter; //Count of Splited Downloading File ;/YSQt)rc>  
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public SiteInfoBean() 21;n0E  
{//nSplitter的缺省值为5 $D45X<  
//default value of nSplitter is 5 
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this("","","",5); `yxk Sb  
} &QE* V  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) @c&)K^v8  
{ $i3/||T,9  
sSiteURL= sURL; htkyywv  
sFilePath = sPath; 7u!p.kN  
sFileName = sName; t%=ylEPW  
this.nSplitter = nSpiltter; *rqih_j0  
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2 {31"  
} QGsUG_/_P  
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public String getSSiteURL() t=U[ ;?  
{ AU >d1S.  
return sSiteURL; gsAc
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} q!FJP9x  
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public void setSSiteURL(String value) ,;{m
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{ zZA I"\;W  
sSiteURL = value; I]} MK?  
} 45_zO#  
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public String getSFilePath() sSvQatwS  
{ TeG
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return sFilePath; v_Jp9  
} MenI>gd?  
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public void setSFilePath(String value) 2Ejs{KUj  
{ fXL$CgXG\x  
sFilePath = value; @jjp\~  
} wCkkfTO  
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9}":}!  
public String getSFileName() ^&.F!  
{ _:TD{EO$  
return sFileName; BI}>"',  
} ;}:"[B3$  
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public void setSFileName(String value) |>p\*Dl}H  
{ ogPxj KSI  
sFileName = value; }z[O_S,X  
} `< VoZ/v  
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public int getNSplitter() D3MuP p-v  
{ ww[STg  
return nSplitter; S6Kaw  
} N>@AsI  
%(
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public void setNSplitter(int nCount) koaH31Q  
{ ZfMJU  
nSplitter = nCount; +DVU"d  
} U^Hymgb%  
} d<#Xqc  
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/* U4Qc$&
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**Utility.java {KODwP'~  
*/ .-nA#/2-  
package NetFox; d~YDg{H  
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public class Utility { B
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public Utility() '9i:b]Hru  
{ C[&Lh_F\  
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} R0{
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//线程睡眠 [NJ!  
public static void sleep(int nSecond) #B>Hq~ vrC  
{ 8qt|2%  
try{ ]%G[<zD,1  
Thread.sleep(nSecond); (}bP`[@rX!  
} MYjDO
>(_  
catch(Exception e) |L0s  
{ $JcU0tPq0  
e.printStackTrace (); {Uu7@1@n  
} tpA7"JD  
} ,]Hn*\@p[c  
~/ "aD  
//日志 q}(UC1|  
public static void log(String sMsg) 5P+
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{ V .
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System.err.println(sMsg); >WG$!o+R  
} !*EHr09N7  
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public static void log(int sMsg) q!}&<w~|  
{ 5Ss=z  
System.err.println(sMsg); 2}+V3/  
} %z1WdiC  
} IOt!A  
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[b
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/* >|H=25N>;  
**TestMethod.java dH?;!sJ  
*/ F5&4x"c  
package NetFox; Ma wio5  
R '"J{oR  
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public class TestMethod { Vk8:;Hj  
9%iqequ  
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public TestMethod() v;{s@CM m  
{ ///xx/weblogic60b2_win.exe oZP:}= F  
try{ HL
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); CEZ*a 0}=  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); NCX!ss  
SiteFileFetch fileFetch = new SiteFileFetch(bean); aY8>#t?  
fileFetch.start(); Y~bp:FkS  
} ;nSaZ$`5  
catch(Exception e){e.printStackTrace ();} T3!l{vG \O  
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} @ttcFX1:W  
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public static void main(String[] args) "7i
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{ 6BNOF66kH  
new TestMethod(); RG#  
} 7$;mkHu4H%  
} /?HRq ?n  
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