http断点续传简单实现（java)

/* TTj] _R{n  
**SiteFileFetch.java 1iR\M4?Frf  
*/ >^9j>< Z  
package NetFox; !lEV^SQJs  
import java.io.*; }.|a0N 5  
import java.net.*; ZUB]qzmK  
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public class SiteFileFetch extends Thread { w].DLoz  
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SiteInfoBean siteInfoBean = null; //文件信息Bean UVi9}zr  
long[] nStartPos; //开始位置 :+_H
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long[] nEndPos; //结束位置 Z] cFbl\ma  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ]OKKR/:  
long nFileLength; //文件长度 J^` pE^S  
boolean bFirst = true; //是否第一次取文件 )06. dZq\  
boolean bStop = false; //停止标志 C;ha2UV0H  
File tmpFile; //文件下载的临时信息 O>rz+8T  
DataOutputStream output; //输出到文件的输出流 &JLKHwi/  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ct*~\C6Ze  
public SiteFileFetch(SiteInfoBean bean) throws IOException ?=iy 6q  
{ 7[kDc-  
siteInfoBean = bean; C\C*@9=&x  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 0""%@X]m  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 
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if(tmpFile.exists ()) !&KE">3Qu  
{ 65&+Fv  
bFirst = false; }VH`\g}  
read_nPos(); = "Lb5!  
} Jn?ZJZ  
else P6^\*xkMr  
{ ='eQh\T)  
nStartPos = new long[bean.getNSplitter()]; wjID*s[  
nEndPos = new long[bean.getNSplitter()]; 9WoTo ,q  
} J{uqbrJICr  
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} jw2hB[WR  
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public void run() Fok`
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{ SV2\vby}C  
//获得文件长度 ~ebm,3?  
//分割文件 1RQM-0W,  
//实例FileSplitterFetch ,8p-EH  
//启动FileSplitterFetch线程 S^e e<%-  
//等待子线程返回 #{bT=:3a  
try{ +>mU4Fwp  
if(bFirst) Z79Y$d>G<E  
{ %.IW H9P7  
nFileLength = getFileSize(); Vc|Q
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if(nFileLength == -1) Mm"0Ip2"  
{ F*B^#AZg  
System.err.println("File Length is not known!"); G"<} s mB  
} ~|wh/]{b9  
else if(nFileLength == -2) Xdf
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{ %8%0l*n'  
System.err.println("File is not access!"); _32 o7}!x  
} !| GD8i  
else =WFG[~8  
{ #)%dG3)e  
for(int i=0;i<nStartPos.length;i++) 9qJ:h-?M  
{ Qo["K}Ty  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); a,*|*Cv  
} 3 _DJ  
for(int i=0;i<nEndPos.length-1;i++) y=y#*yn&  
{ kvt"7;(  
nEndPos = nStartPos[i+1]; (TGG?V  
} [*=UH*:'N  
nEndPos[nEndPos.length-1] = nFileLength; h4M>k{  
} 0s%{m<  
} 2mvp|<"  
}cy<$=c#E_  
_3Q8R}  
//启动子线程 A}
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; `~W?a  
for(int i=0;i<nStartPos.length;i++) &>auW}r  
{ O`0A#h&No  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), DVyxe
}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), :"oUnBY%  
nStartPos,nEndPos,i); tj!~7lo  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _ <pO<S  
fileSplitterFetch.start(); M*jn8OE  
} 1QuR7p  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Ba|76OBRJ  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); $k3l[@;hE  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 71yf+xL  
nEndPos = " + nFileLength); `>}e 5  
// fileSplitterFetch[nPos.length-1].start(); Zo5.Yse  
v/7iu*u  
F, p~O{ Q  
//等待子线程结束 dr7ry"5Zq  
//int count = 0; :j#Fq d[DF  
//是否结束while循环 .[:*bo3  
boolean breakWhile = false; FHu+dZ  
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while(!bStop) (V+iJ_1g{  
{ +D+Rf,D  
write_nPos(); w=75?3c7F  
Utility.sleep(500); k<NEauQ  
breakWhile = true; z2A1h!Me  
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for(int i=0;i<nStartPos.length;i++) XFN4m
#  
{ V\o&{7!  
if(!fileSplitterFetch.bDownOver) 0j|JyS:}G  
{ @460r  
breakWhile = false; Gl>_C@n0h  
break; !tofO|E5  
} ::rKW*?  
} -}*YfwK  
if(breakWhile) MXU8QVSY"  
break; 41`&/9:"_M  
4m$Xjj`vE  
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//count++; dD8f`*"*=  
//if(count>4) HBnnIbEtF'  
// siteStop(); )[hQK_e]  
} 5S?+03h~  
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System.err.println("文件下载结束！"); pO_L,~<  
} ({AqL#x`u  
catch(Exception e){e.printStackTrace ();} | sio:QP  
} =XT}&D6  
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//获得文件长度 5}t}Wc8  
public long getFileSize() (>\w8]  
{ ww"HV;i  
int nFileLength = -1; 7Z<ba^
r}  
try{ kMLWF  
URL url = new URL(siteInfoBean.getSSiteURL()); hzjEO2  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2aUy1*aM  
httpConnection.setRequestProperty("User-Agent","NetFox"); YAf`Fnmw  
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int responseCode=httpConnection.getResponseCode(); ! uyC$8V*l  
if(responseCode>=400) AGxG*KuZ  
{ #2023Zo]  
processErrorCode(responseCode); wfxg@<WR  
return -2; //-2 represent access is error Z>H y+Q4  
} dLMKfh/4Q  
2,X~a;+  
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String sHeader; $NtbI:e{  
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for(int i=1;;i++) n^AQ!wC  
{ 2& l~8,  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); hs"=>(P)  
//Utility.log(in.readLine()); o4"7i 9+g  
sHeader=httpConnection.getHeaderFieldKey(i); M1/Rba Q  
if(sHeader!=null) q-fxs8+m|  
{ ( o_lH2  
if(sHeader.equals("Content-Length")) !5P\5WF~Y  
{ _JjR= m  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); O:Fnxp5@  
break; 1c} %_Z/  
} A%pBvULH  
} #X(KW&;m  
else
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break; IE-c^'W=}m  
} jCMr[ G=  
} AVys`{*c  
catch(IOException e){e.printStackTrace ();} $i+ 1a0%n  
catch(Exception e){e.printStackTrace ();} ni@N/Z?!pA  
}0P5~]S<5A  
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Utility.log(nFileLength); n%>c4*t  
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return nFileLength; C[ ehw  
} I'h6!N"  
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//保存下载信息（文件指针位置） \lnpsf  
private void write_nPos() Ls#=R  
{ ]iyJ>fC  
try{ ESl-k2  
output = new DataOutputStream(new FileOutputStream(tmpFile)); u2SnL$A7  
output.writeInt(nStartPos.length); #l6L7u0~wC  
for(int i=0;i<nStartPos.length;i++) s^]F4'  
{ WvN!8*XFM  
// output.writeLong(nPos); y^#jM  
output.writeLong(fileSplitterFetch.nStartPos); 8#9d
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output.writeLong(fileSplitterFetch.nEndPos); L)5YX-?  
} Jbud_.h9  
output.close(); J3oj}M*  
} DL5`A?/  
catch(IOException e){e.printStackTrace ();} <wt#m`Za  
catch(Exception e){e.printStackTrace ();} #4ZDY,>Xi#  
} t UJ m}+=>  
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//读取保存的下载信息（文件指针位置） Ub%al
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private void read_nPos() o!`.LL%  
{ !}D!_z,)u  
try{ G
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); uM\(#jZ  
int nCount = input.readInt(); m/)Wn  
nStartPos = new long[nCount]; }vRs n-E@  
nEndPos = new long[nCount]; =gCv`SFW  
for(int i=0;i<nStartPos.length;i++) bY4~\cP.  
{ 3d^zLL  
nStartPos = input.readLong(); sD,[,6(  
nEndPos = input.readLong(); HG2i^y  
} *<yKT$(+_  
input.close(); W_NQi  
} )S
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catch(IOException e){e.printStackTrace ();} %t&5o>1C  
catch(Exception e){e.printStackTrace ();} X&1R6O  
} -'FzH?q:  
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private void processErrorCode(int nErrorCode) 0f
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{ $= '_$wG 8  
System.err.println("Error Code : " + nErrorCode); KJ]:0'T  
} \Gh]$sp  
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 o*2TH2  
//停止文件下载 sjpcz4|K  
public void siteStop() bE-{ U/;  
{ `B+P$K<X  
bStop = true; jg]_'^pVzr  
for(int i=0;i<nStartPos.length;i++) [:x^ffs  
fileSplitterFetch.splitterStop(); gdupG  
/ vI sX3v  
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} PiMW29B^  
} PpPg ~ix*  
//负责部分文件的抓取 opQ%!["N  
**FileSplitterFetch.java =,q,W$-  
*/ :yN;_bC!b%  
package NetFox; qEC-'sl<  
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import java.io.*; B w1ir  
import java.net.*; TFbMrIF  
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public class FileSplitterFetch extends Thread { _RT3Fk  
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String sURL; //File URL ^EGe%Fq*x]  
long nStartPos; //File Snippet Start Position P9~7GFas|  
long nEndPos; //File Snippet End Position =W(mZ#*vdY  
int nThreadID; //Thread's ID ^2L\Y2  
boolean bDownOver = false; //Downing is over 9Xb,Swo~  
boolean bStop = false; //Stop identical <]6])f,y\  
FileAccessI fileAccessI = null; //File Access interface ,E{z+:Es  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException @^8tk3$Y  
{ 
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this.sURL = sURL; X}.y-X#v5J  
this.nStartPos = nStart; ~y.{WuUD  
this.nEndPos = nEnd; (9r\YNK  
nThreadID = id; "oZ-W?IKE  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 h}&WBN  
} T8& kxp  
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1 "'t5?XW  
public void run() t|Cp<k]B  
{ uGIA4CUm  
while(nStartPos < nEndPos && !bStop) 1!,xB]v1Ri  
{ 3.M<ATe^  
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try{ B#Rw
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URL url = new URL(sURL);
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); " N)dle,  
httpConnection.setRequestProperty("User-Agent","NetFox"); *oAv:8"iY  
String sProperty = "bytes="+nStartPos+"-"; P;o6rQf  
httpConnection.setRequestProperty("RANGE",sProperty); %~`8F\Hiu  
Utility.log(sProperty); D_oGhQYY4  
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InputStream input = httpConnection.getInputStream(); C8qA+dri  
//logResponseHead(httpConnection); 5)fEs.r0U  
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byte[] b = new byte[1024]; s`W
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int nRead; T#'+w@Q9{9  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) \IJ\  
{ u_[^gS7
 
nStartPos += fileAccessI.write(b,0,nRead); /QDlm>FM4  
//if(nThreadID == 1) 5$o]
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); G8%Q$  
} f/t1@d!  
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&WN#HI."]  
Utility.log("Thread " + nThreadID + " is over!"); lhsd39NM  
bDownOver = true; iM;7V*u  
//nPos = fileAccessI.write (b,0,nRead); WZq0$:I;R  
} IXYSZ)z  
catch(Exception e){e.printStackTrace ();} Fm(~Vt;%u  
} @vWf-\  
} nQ4s  
@!z9.o;  
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//打印回应的头信息 J(+I`  
public void logResponseHead(HttpURLConnection con) LB}y,-vX>  
{ '<"eG!O  
for(int i=1;;i++) #g,JNJ}  
{ 'EFSr!+  
String header=con.getHeaderFieldKey(i); 23XSQHVx  
if(header!=null) 8s6~l.
v  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); r8\"'4B1  
Utility.log(header+" : "+con.getHeaderField(header)); `9QvokD  
else C2RR(n=N^  
break; :7&#ej6  
} \ FW{&X9a  
} 0{bGVLp  
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public void splitterStop() ,L ;ueAo  
{ 'V";"Ei  
bStop = true; j)IXe 0dMC  
} :#8#tLv  
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} /Po't(-x  
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/* w'[lIEP 2$  
**FileAccess.java ]$[J_f*x  
*//文件访问(定位，写) _^cDB1I?  
package NetFox; 49b#$Xq  
import java.io.*; &|('z\k  
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public class FileAccessI implements Serializable{ kL;sA'I:S  
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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 GtcY){7  
RandomAccessFile oSavedFile; VfAC&3%M
 
long nPos; bqEQP3t^  
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public FileAccessI() throws IOException :
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{ zbsdK  
this("",0);  y/t{*a  
} PLDg'4DMg  
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public FileAccessI(String sName,long nPos) throws IOException (jYHaTL6Y'  
{ S;#S3?G  
oSavedFile = new RandomAccessFile(sName,"rw"); ab?   
this.nPos = nPos; +92/0
 
oSavedFile.seek(nPos); v%O KOrJ  
} y\Kr@;q0w  
H,`F%G#!`q  
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public synchronized int write(byte[] b,int nStart,int nLen) >p#`%S  
{ 6yk=4l\  
int n = -1; >)*'w!  
try{ \MBbZB9@  
oSavedFile.write(b,nStart,nLen); -
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n = nLen; eJA$J=^R;  
} OE
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catch(IOException e) }U3+xl6g  
{ sC >_ulkoa  
e.printStackTrace (); [ZC]O2'  
} Q^X  
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l?pF
?({  
return n; lM1~K  
} cb!mV5M-g  
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} MCOiB<L6  
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/* `)V1GR2 ES  
**SiteInfoBean.java -n&g**\w  
*/ e$]`  
package NetFox; K"u-nroHW  
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public class SiteInfoBean { yUV0{A-q{0  
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 8:=&=9%  
private String sSiteURL; //Site's URL pF kA,  
private String sFilePath; //Saved File's Path +UbSqp1BS  
private String sFileName; //Saved File's Name eewhT^  
private int nSplitter; //Count of Splited Downloading File Xi$( U8J_  
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public SiteInfoBean() n@5Sp2p  
{//nSplitter的缺省值为5 8K+(CS>xvO  
//default value of nSplitter is 5 ldp x,  
this("","","",5); ql"&E{u?  
} gc(Gc vdB\  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) yg({g "  
{ m$<LO%<~p  
sSiteURL= sURL; \f| Hk*@  
sFilePath = sPath; DV+M;rs  
sFileName = sName; ?bFP'.  
this.nSplitter = nSpiltter; k1tJ$}  
5=/&[=  
/`(Kbwh  
} 0XouHU  
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public String getSSiteURL() WP7RX|7  
{ dRwOt  
return sSiteURL; @z $,KUH  
} GX2aV6}  
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public void setSSiteURL(String value) n>Cl;cN=  
{ cr GFU?8  
sSiteURL = value;  1B}q?8n  
} [/dGOl+  
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public String getSFilePath() Bmx+QO  
{ w2*.3I,~)B  
return sFilePath; [zXKS|  
} VnlgX\$}  
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public void setSFilePath(String value) /V'^$enK!}  
{ 'Br:f_}  
sFilePath = value; y98v  
} s|er+-'  
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public String getSFileName() (!b_o A8V  
{ w+A:]SU  
return sFileName; (EW<Ggi  
} [3$L}m  
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public void setSFileName(String value) "ijpqI  
{ EY~b,MIL4  
sFileName = value; \9;SOAv  
} vjo@aY.x  
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public int getNSplitter() )1CYs4lp  
{ )"(
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return nSplitter; 8aDSRfv*  
} hz:^3F`>/&  
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public void setNSplitter(int nCount) kg,t[Jl  
{ >L5fc".  
nSplitter = nCount; z+@CzHCN  
} yH`4sd  
} !-G'8a|7  
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/* u_kcuN\Sq  
**Utility.java ceiUpWMu,  
*/ kXjrc  
package NetFox; ,E7+Z' ;  
(tZ#EL0  
01N]|F:  
public class Utility { a#i85su  
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public Utility() CMQlxX?  
{ !WTZ=|  
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} oAnNdo  
A/bxxB7w  
//线程睡眠 VV_Zrje  
public static void sleep(int nSecond) [G.4S5FX.]  
{ 0<g;g%   
try{ =D&xw2  
Thread.sleep(nSecond); 8`\^wG$W  
} i|`b2msvd  
catch(Exception e) Sf_q;Ws  
{ _'eG  
e.printStackTrace (); |)%]MK$;  
} /6?A#%hc  
} ,s=jtK  
gzHMZ/31  
//日志 JPo.&5k  
public static void log(String sMsg) 33R1<dRk  
{ D)kh"cK*1  
System.err.println(sMsg); B/:
+(|  
} %_kXC~hH_  
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public static void log(int sMsg) X jJV  
{ tYe+7s  
System.err.println(sMsg); Z`FEB0$  
} uq
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} m7dpr$J  
`5HFRgL`.
 
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/* V
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**TestMethod.java \vH /bL  
*/ G<F+/Oi&DX  
package NetFox; >M}\_c=  
| c:E)S\  
R04%;p:k#  
public class TestMethod { k!&G;6O-  
|igr3p5Fw  
Z$UPLg3=;_  
public TestMethod() bCV3h3<  
{ ///xx/weblogic60b2_win.exe >DFpL$oP  
try{ MC 8t"SB  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); *qX!  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); p"xti+2,  
SiteFileFetch fileFetch = new SiteFileFetch(bean); o{W4@:Ib  
fileFetch.start(); R*"31&3le4  
} Qkk3>{I  
catch(Exception e){e.printStackTrace ();} +*W9*gl  
3 s@6pI  
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} @ij8AGE:  
2H,^i,  
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public static void main(String[] args) z~O#0Q!  
{ &-S;.}  
new TestMethod(); BLepCF38  
} 3SI~?&HU!/  
} +hUS sR&  
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