http断点续传简单实现（java)

/* %n h
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**SiteFileFetch.java _io+YzS  
*/ d/bEt&  
package NetFox; hRty [  
import java.io.*; Dh5X/y  
import java.net.*; p;W.lcO`0  
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public class SiteFileFetch extends Thread { 'ow.=1N-
 
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SiteInfoBean siteInfoBean = null; //文件信息Bean -5T=:2M  
long[] nStartPos; //开始位置 :_t}QP"  
long[] nEndPos; //结束位置 J2j U4mR  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 i{ \%e  
long nFileLength; //文件长度 \'9PZ6q{  
boolean bFirst = true; //是否第一次取文件 cG?cUw).E  
boolean bStop = false; //停止标志 n84GZ5O>7  
File tmpFile; //文件下载的临时信息 |fSe>uVZ  
DataOutputStream output; //输出到文件的输出流 U7I qST  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） /\H>y  
public SiteFileFetch(SiteInfoBean bean) throws IOException 6S+U&Ce\  
{ j{NNSi3  
siteInfoBean = bean; f-5:wM&  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); VY)9|JJCO  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); z}{afEb  
if(tmpFile.exists ()) #{=;NuP  
{ x-?{E
  
bFirst = false; :PtF+{N>  
read_nPos(); pp
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} tUgEeh6  
else 2Sh  
{ NMww>80  
nStartPos = new long[bean.getNSplitter()]; vP!{",>  
nEndPos = new long[bean.getNSplitter()]; K^B%/T]d  
} J,zO2572u  
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} gS:A'@&  
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public void run() \#rI
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{ E@P %v{)  
//获得文件长度 Qu7T[<  
//分割文件 >P/][MT  
//实例FileSplitterFetch fm^@i;D  
//启动FileSplitterFetch线程 z8[yt282  
//等待子线程返回 2KQoy;  
try{ ;>AL`M+  
if(bFirst) :<Fe  
{ WyZL9K{?  
nFileLength = getFileSize(); x ul]m*Z  
if(nFileLength == -1) [p2H=  
{ 4T?h  
System.err.println("File Length is not known!"); tqy@iEz+  
} on8WQf'A#  
else if(nFileLength == -2) P)uDLFp]  
{ +n7?S~R$  
System.err.println("File is not access!"); (%U@3._  
} E"L2&.  
else 1Jj Y!  
{ CEC nq3  
for(int i=0;i<nStartPos.length;i++) YFTjPBV  
{ ;r6jx"i  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); tw(JZDc  
} [2dn\z28  
for(int i=0;i<nEndPos.length-1;i++) (E,Yo  
{ Raw)9tUt  
nEndPos = nStartPos[i+1]; z.6$W^  
} |Xw/E)jA  
nEndPos[nEndPos.length-1] = nFileLength; VOr1  
} NBF MN%  
} g/&T[FOr  
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//启动子线程 F|&{Rt  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; k2xHH$+{#=  
for(int i=0;i<nStartPos.length;i++) 7y`}PMn  
{ 9<vWcq*4  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 1&/FG(*/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),
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nStartPos,nEndPos,i); gh>>Ibf  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1lsLJ4P  
fileSplitterFetch.start(); C_ \q?>  
} 3&x-}y~sg  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )~V4+*<  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); :0/q5_t  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", )I\=BPo|B  
nEndPos = " + nFileLength); zvvP81$W  
// fileSplitterFetch[nPos.length-1].start(); 0I{
gJSK.,  
unJ R=~E  
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//等待子线程结束 |8bq>01~  
//int count = 0; 8_&CT :u>  
//是否结束while循环 '&99?s`u  
boolean breakWhile = false; |ea~'N1  
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while(!bStop) >3gi yeJ  
{ UA~RK2k?  
write_nPos(); CAT.4GM  
Utility.sleep(500); Jd,)a#<j  
breakWhile = true; ?k[p<U
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for(int i=0;i<nStartPos.length;i++) f(D_FTTO  
{ Kd3?I5t  
if(!fileSplitterFetch.bDownOver) aS}1Q?cU  
{ WhBpv(q}.  
breakWhile = false; PS S?|Vk  
break; <?0~1o\Ur  
} !'=15&5@  
} ?4G|+yby  
if(breakWhile) ?8,%
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break; ZAuWx@}  
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//count++; }%TSGC4{  
//if(count>4) X~Rl 6/,  
// siteStop(); o$.e^XL  
} @^ ik[9^H  
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System.err.println("文件下载结束！"); ?yXAu0  
} Lh$dzHq  
catch(Exception e){e.printStackTrace ();} Wk4.%tpeO7  
} l_/C65%.:  
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//获得文件长度 iF+RnWX\  
public long getFileSize() V+wH?H=  
{ VyG4(Xva  
int nFileLength = -1; MVv1.6c7Y  
try{ O(H1P[  
URL url = new URL(siteInfoBean.getSSiteURL()); t>UkE9=3\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); N?4q  
httpConnection.setRequestProperty("User-Agent","NetFox");  PWgDFL?  
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int responseCode=httpConnection.getResponseCode(); +UWU|:  
if(responseCode>=400) s]B"qFA  
{ `BZ&~vJ_  
processErrorCode(responseCode); E^ h=!RW{  
return -2; //-2 represent access is error K7vw3UwGN  
} H ;@!?I  
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String sHeader; @fn6<3  

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for(int i=1;;i++) @y~P&HUN  
{ vrl[BPI  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Il~01|3+m  
//Utility.log(in.readLine()); 17UK1Jx,  
sHeader=httpConnection.getHeaderFieldKey(i); 3-wD^4)O,  
if(sHeader!=null) Nofu7xiDw[  
{ f_r0})  
if(sHeader.equals("Content-Length")) l`n5~Fs  
{ ddpl Pzm#  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); @6xGJ,s  
break; \MYU<6{u  
} z)L}ECZh9  
} m^Lj+=Z"  
else \gKdDS  
break; I^0t2[M  
} Xza
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} 0-e  
catch(IOException e){e.printStackTrace ();} >2-F2E,  
catch(Exception e){e.printStackTrace ();} T[Q"}&bB  
 Q9y*:  
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Utility.log(nFileLength); 6mG3fMih.  
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return nFileLength; Yw"P)Zp  
} E[S':Q  
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//保存下载信息（文件指针位置） Zq?_dIX %  
private void write_nPos() ^87
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{ ?V+wjw  
try{ P>htQ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); R7aXR\ R  
output.writeInt(nStartPos.length); STT2o=  
for(int i=0;i<nStartPos.length;i++) I6w/0,azC  
{ 1i,4".h?M  
// output.writeLong(nPos); gX/NtO%  
output.writeLong(fileSplitterFetch.nStartPos); {[3YJkrM  
output.writeLong(fileSplitterFetch.nEndPos); Dc:DY:L^  
} 5EhE`k4  
output.close(); BMjfqX  
} *)%dXVf  
catch(IOException e){e.printStackTrace ();} syFI$rf _  
catch(Exception e){e.printStackTrace ();} aJ-}  
} M.k|bh8  
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//读取保存的下载信息（文件指针位置） 8kbBz  
private void read_nPos() A+2oh3  
{ TzY!D*%z  
try{ 6UB6;-  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Tf l;7w.(A  
int nCount = input.readInt(); 7|~:P$M  
nStartPos = new long[nCount]; QN #)F  
nEndPos = new long[nCount]; q!2<=:f  
for(int i=0;i<nStartPos.length;i++) ;Uk!jQh  
{ u%aFb*  
nStartPos = input.readLong(); E4m:1=Nd~]  
nEndPos = input.readLong(); .;Z.F7{q  
} 5&%fkZ0  
input.close(); ((9YG  
} [tN` :}?  
catch(IOException e){e.printStackTrace ();} Ut;'Gk  
catch(Exception e){e.printStackTrace ();} z@`@I  
} pX]21&F  
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private void processErrorCode(int nErrorCode) S-P{/;c@  
{ ~h|m&XK+Q  
System.err.println("Error Code : " + nErrorCode); |$Xf;N37t  
} 65"uD7;  
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{9{J^
@@  
//停止文件下载 $O]^Xm3{@  
public void siteStop() #XL`S  
{ $P_x
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bStop = true; UFk!dK+  
for(int i=0;i<nStartPos.length;i++) w=$'Lt!  
fileSplitterFetch.splitterStop(); k) 3s
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} |P~q/Wff  
} Y`=z.D{  
//负责部分文件的抓取 P09,P
  
**FileSplitterFetch.java omT(3)TP  
*/
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package NetFox; 6.UKB<sV  
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import java.io.*; #\0TxG5'QA  
import java.net.*; .CvFE~  
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public class FileSplitterFetch extends Thread { ofl'G]/$+  
"p`o]$Wv  
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String sURL; //File URL :=Nb=&lst  
long nStartPos; //File Snippet Start Position ifd}]UMQ  
long nEndPos; //File Snippet End Position AO^]>/7ed  
int nThreadID; //Thread's ID 0+p 5/5  
boolean bDownOver = false; //Downing is over %/X2 l  
boolean bStop = false; //Stop identical O68bzi]  
FileAccessI fileAccessI = null; //File Access interface ^YqbjL  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :K:f^o]s  
{ 5W|u5AIw  
this.sURL = sURL; 22PGWSQ  
this.nStartPos = nStart; i5Eeg`NMl  
this.nEndPos = nEnd; >b3@>W  
nThreadID = id; [:Xn6)qz  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 $>EqH?EQ  
} |E? ,xWN  
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public void run() ^z38<L=z"  
{ |^>u<E5  
while(nStartPos < nEndPos && !bStop) bd.j,4^  
{ W3"vTZJF  
c 3}x)aQ  
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try{ F{kG  
URL url = new URL(sURL); <` #,AVH  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); \f6lT3"VN  
httpConnection.setRequestProperty("User-Agent","NetFox"); CgN]dx*`  
String sProperty = "bytes="+nStartPos+"-";
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httpConnection.setRequestProperty("RANGE",sProperty); Z4=_k{*  
Utility.log(sProperty); sYl&Q.\q  
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InputStream input = httpConnection.getInputStream(); @wg&6uQ  
//logResponseHead(httpConnection); [5x+aW%ql  
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byte[] b = new byte[1024]; MacL3f  
int nRead; 3S;>ki4(0  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 2=i+L z^  
{ IiG4ib>)W  
nStartPos += fileAccessI.write(b,0,nRead); Bidqf7v  
//if(nThreadID == 1) Iz 1*4@  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); J,CJPUf&  
} Y+|L3'H  
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Utility.log("Thread " + nThreadID + " is over!"); Pc/.*kOT  
bDownOver = true; `HE>%=]b  
//nPos = fileAccessI.write (b,0,nRead); pE9aT5 L  
} JrY"J]/  
catch(Exception e){e.printStackTrace ();} d,Im&j_Z  
} fx8y`8}_  
} V#n?&-{V  
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//打印回应的头信息 \9&YV;Ct  
public void logResponseHead(HttpURLConnection con) 3C E 39W  
{ &!3VqHQ`  
for(int i=1;;i++) FCS5@l,'<  
{ @vVRF Z  
String header=con.getHeaderFieldKey(i); H24ate?t,  
if(header!=null) RPa?Nv?e  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); %fexuy4  
Utility.log(header+" : "+con.getHeaderField(header)); eSQzjR*  
else #dxJ#  
break; nN(D7wk  
} ,_wm,  
} %zIl_/s  
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public void splitterStop() `\WcF7  
{ UH1S_:6  
bStop = true; oF 1W
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} ,6%hu|Y
*  
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} W>t&N  
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8VAYIxRv  
/* =0!\F~  
**FileAccess.java ZmYSi$B  
*//文件访问(定位，写) /I`bh  
package NetFox; ^J*G%*  
import java.io.*; tehI!->l  
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public class FileAccessI implements Serializable{ |4?}W ,  
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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 J6^Ct  
RandomAccessFile oSavedFile; S$kuhK>W!  
long nPos; ,;+91lR3  
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public FileAccessI() throws IOException fEv<W  
{ bN7UO  
this("",0); ou,=MpXx*  
} bsk=9K2_2t  
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0
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public FileAccessI(String sName,long nPos) throws IOException Kn!0S<ssR  
{ jhEg#Q$  
oSavedFile = new RandomAccessFile(sName,"rw"); E23 Yk?"  
this.nPos = nPos; U<,Kw6K  
oSavedFile.seek(nPos); 4htSwK+  
} pJ*#aH[ySP  
dD.d?rnZq7  
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public synchronized int write(byte[] b,int nStart,int nLen) 1f pS"_}  
{ YaJ{"'}  
int n = -1; Vw;ldEdx  
try{ b[[6X  
oSavedFile.write(b,nStart,nLen); :2UC{_  
n = nLen; Uh|__DUkh  
} 6nWx>R<  
catch(IOException e) 8$
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{ yL3<X
w|  
e.printStackTrace (); 4(0t GF  
} g=YiR/O1QN  
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return n; =u3@ Dhw  
} IL6f~!  
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} &pY G  
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/* E#2k|TpH4  
**SiteInfoBean.java v.2Vg  
*/ nM.?Q}yO~  
package NetFox; L|1zHDxQ  
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public class SiteInfoBean { FeeWZe0i  
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private String sSiteURL; //Site's URL qD%&\ZT  
private String sFilePath; //Saved File's Path |UDD/
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private String sFileName; //Saved File's Name =O'%)Y&  
private int nSplitter; //Count of Splited Downloading File A{Htpm~  
Q%VR@[`\  
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public SiteInfoBean() gL}Y5U+s  
{//nSplitter的缺省值为5 >.w
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//default value of nSplitter is 5 KIBZQ.uG  
this("","","",5); S@G{|.)2  
} 2d;xAX]  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) @$yYljP  
{ 9egaN_K  
sSiteURL= sURL; dlzamoS@AR  
sFilePath = sPath; VrE5^\k<a  
sFileName = sName; +M]8_kE=+l  
this.nSplitter = nSpiltter; {BCj
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A}Dpw[Q2@8  
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} })SdaZ  
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public String getSSiteURL() GXlg%  
{ jh&vq=PH  
return sSiteURL; M*6@1.n  
} ?[B[ F  
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public void setSSiteURL(String value) de47O  
{ GFa/9Bi  
sSiteURL = value; K
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} be%*0lr  

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public String getSFilePath() $cU/Im`  
{ K/+C6Y?  
return sFilePath; `80Hxp@  
} TPFmSDq  
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public void setSFilePath(String value) oz-I/g3go  
{ RAbq_^Q  
sFilePath = value; (+ anTA=  
} |6^
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public String getSFileName() =T}uQ$X  
{ t3g!5  
return sFileName; }3y\cv0ct  
} VVl-cU  
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public void setSFileName(String value) beZ| i 1:  
{ zL8A?G)=M  
sFileName = value; }
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} 7!nAWlQ&-E  
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&~f_1<  
public int getNSplitter() S]/+n>  
{ KZfRiCZ  
return nSplitter; S6tH!Z=(g  
} |R
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Yg?{x@  
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public void setNSplitter(int nCount) 0|;=mYa4M  
{ CHI(\DXNs  
nSplitter = nCount;  +'.Q-  
} #?6RoFgMe  
} 0+pJv0u  
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/* &}1)]6q$  
**Utility.java NL
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*/ G)7sXEe  
package NetFox; 3k^jR1  
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0{F.DDiNT  
public class Utility { {H2i+"cF  
q|J]  
S &u94hlC  
public Utility() [=+/  
{ 6~>k]G  
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} `f]O  
sf0U(XYQ^  
//线程睡眠 W$S.?[
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public static void sleep(int nSecond) |3m%d2V*hF  
{ uLF55:`<  
try{ oVW?d]R  
Thread.sleep(nSecond); mM.&c5U  
} 9G~P)Z!0  
catch(Exception e) [dMxr9M  
{ :^a$ve3(Jq  
e.printStackTrace (); ,-)1)R\.  
} /$(D>KU  
} vNGvEJ`qn  
( Iew%U  
//日志 W:\VFPf2  
public static void log(String sMsg) gzF&7trN  
{ <!^Z|E  
System.err.println(sMsg); ^ZG1  
} NY x4& *le  
t/|^Nt@XT  
Di*>PE
@  
public static void log(int sMsg) 6-"&jbvm  
{ :xCobMs_/  
System.err.println(sMsg); ny=iAZM>q  
} F1>,^qyG6  
} ^ a:F*<D  
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E<dN=#f6  
/* fp0Va!T(V  
**TestMethod.java 1~
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*/ |:z%7J3wP  
package NetFox; Yo:&\a K[  
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public class TestMethod { DxHeZQ"LL  
:Kiu*&{  
&kvVMnok  
public TestMethod() qb&*,zN  
{ ///xx/weblogic60b2_win.exe u2QJDLMJv  
try{ J++D\x#@  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); )Pq.kn{Sp  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); K4BMa]/U  
SiteFileFetch fileFetch = new SiteFileFetch(bean); S[M$>  
fileFetch.start(); \X!!(Z;6A  
} P;Ox|  
catch(Exception e){e.printStackTrace ();} WlUE&=|Oz2  
#Z :r  
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} 6F2}|c  
#LiC@>  
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public static void main(String[] args) ^d,d<Uc  
{ 6]VTn-  
new TestMethod(); v|6fqG+Q\  
} y@I"Hk<T  
} pN[i%\vh  
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