http断点续传简单实现（java)

/* Rli
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**SiteFileFetch.java BJqb'Hjd  
*/ }}wSns  
package NetFox; [mF=<G"  
import java.io.*; VotI5O $  
import java.net.*; \;+b1  
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public class SiteFileFetch extends Thread { 5^Lb
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SiteInfoBean siteInfoBean = null; //文件信息Bean UYpln[S  
long[] nStartPos; //开始位置 VD{_
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long[] nEndPos; //结束位置 $<f+CtD4  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ePxf.U  
long nFileLength; //文件长度 zj=F4]w  
boolean bFirst = true; //是否第一次取文件 'NnmLM(oh  
boolean bStop = false; //停止标志 T n,Ifo3  
File tmpFile; //文件下载的临时信息 2XeNE[  
DataOutputStream output; //输出到文件的输出流 PG'I7)Bv  
2 xi@5;!  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） W#^p%?8pR  
public SiteFileFetch(SiteInfoBean bean) throws IOException 5=!aq\ 5  
{ `$
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siteInfoBean = bean; x o72JJ  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 3>z+3!I z  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Kn\$\?u  
if(tmpFile.exists ()) ,- _ReL  
{ J^Wqa$<;"  
bFirst = false; OW8TiM mK  
read_nPos(); ; d}  
} ;bq EfV0`2  
else hia
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{ ;kVo? W]  
nStartPos = new long[bean.getNSplitter()]; pf0uwXo  
nEndPos = new long[bean.getNSplitter()]; &<C&(g{Z  
} =gSACDTc  
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} k59.O~0V  
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public void run() QSOJHRl=C  
{ .r@'9W^8  
//获得文件长度 fXkemB^)_  
//分割文件 ]8opI\  
//实例FileSplitterFetch G""=`@  
//启动FileSplitterFetch线程 ,Lw '3  
//等待子线程返回 >Wj8[9zf  
try{ 2K2jko9'a  
if(bFirst) cp+eh  
{ M]e _@:!  
nFileLength = getFileSize(); }$s._)a  
if(nFileLength == -1) 9K{0x7~  
{ uC1
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System.err.println("File Length is not known!"); et}s yPH  
} w"j[c#vM  
else if(nFileLength == -2) ?^: xNRE$j  
{ `ln=D$  
System.err.println("File is not access!"); q5~fU$ ,  
} 1)M%]I4  
else DFqVZ  
{ nZUBblRJ)  
for(int i=0;i<nStartPos.length;i++) {7FD-Q[tS  
{ ;p)fW/<  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); [kZe6gYP&  
} }-M%$~`  
for(int i=0;i<nEndPos.length-1;i++) 1Q9eS&  
{ H3o Um1  
nEndPos = nStartPos[i+1]; 7ZgFCK,8m,  
} z^9df(  
nEndPos[nEndPos.length-1] = nFileLength; $qhVow5~  
} p"J\+R  
} .{k^ tf4  
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//启动子线程 ?I#zcD)w  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; `LVX|l62  
for(int i=0;i<nStartPos.length;i++) FYeUz$/  
{ *:V"C\`^n  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), aAkO>X%[  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 1He'\/#  
nStartPos,nEndPos,i); RIxGwMi%  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @Tf5YZ*  
fileSplitterFetch.start(); XZ&q5]PJI  
} <rFY$ ?x  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), :ugj+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); eVbaxL!Q^  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", [z`m`9Aq  
nEndPos = " + nFileLength); }c*6|B@f  
// fileSplitterFetch[nPos.length-1].start(); vc(6lN9>  
q9c:,k  
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//等待子线程结束 N{6Lvq[8  
//int count = 0; Y>[u(q&09O  
//是否结束while循环 \
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boolean breakWhile = false; ^ $t7p 1  
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while(!bStop) ``mW\=fe  
{ /8w _jjW  
write_nPos(); $ OMGo`z  
Utility.sleep(500); u4[3JI>  
breakWhile = true; i<nUp1r(  
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for(int i=0;i<nStartPos.length;i++) g&"__~dS-F  
{
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if(!fileSplitterFetch.bDownOver) 9*}?0J8  
{ =-dk@s  
breakWhile = false; \[w82%U  
break; !jxz
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} {!hA^[}|  
} Jm8#M z  
if(breakWhile) D0=H&Z[  
break; P:yMj&)  
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&Rx-zp&dJ  
//count++; OQON~&~  
//if(count>4) ?5!>k^q  
// siteStop(); RHGs(d7-  
} @OlV6M;qJ  
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System.err.println("文件下载结束！"); D-BWgK  
} Td5;bg6Qy  
catch(Exception e){e.printStackTrace ();} VL/%D*  
} fK|F`F2V  
*gC6yQ2?  
6A]Ia4PL  
//获得文件长度 :8bz+3p  
public long getFileSize() S5Q$dAL  
{ {uRnZ/m  
int nFileLength = -1; YRYAQj/7  
try{ cM;&$IjCt  
URL url = new URL(siteInfoBean.getSSiteURL()); ^L(}cO  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;$\d^i{N  
httpConnection.setRequestProperty("User-Agent","NetFox"); /CAi%UH,F  
S&@uY#_(*T  
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int responseCode=httpConnection.getResponseCode(); FXPw5  
if(responseCode>=400) hYW<4{Gjr  
{ DM%4V|F"  
processErrorCode(responseCode); PZRm.vC)k  
return -2; //-2 represent access is error %<q l  
} gekW&tRie  
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String sHeader;  ajayj|h  
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for(int i=1;;i++) }F1|& A  
{ J:,>/')n  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); zUqt^_  
//Utility.log(in.readLine()); t/K<fy 6  
sHeader=httpConnection.getHeaderFieldKey(i); I"^ `!8<q  
if(sHeader!=null) 6Uk[_)1  
{ zR_#c3o  
if(sHeader.equals("Content-Length")) !tT$}?Ano  
{ VGY#ph%  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 1Ig@gdmz  
break; j1)HIQE|5f  
} RbJ,J)C>  
} A|V |vT7cb  
else hmOhXE[a&  
break; cZN+D D  
} >`a)gky%~  
} dIG(7~  
catch(IOException e){e.printStackTrace ();} \w!G  
catch(Exception e){e.printStackTrace ();} ki#O ^vl  
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Utility.log(nFileLength); /s>ZT8vaAs  
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return nFileLength; 2yhtJ9/  
} [EDw0e  
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;SF0}51  
//保存下载信息（文件指针位置） iq '3.-xYr  
private void write_nPos()  '._8  
{ Yz0ruhEMk  
try{ mfO:#]
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output = new DataOutputStream(new FileOutputStream(tmpFile)); zm}4=Kz}  
output.writeInt(nStartPos.length); N0h"EV[  
for(int i=0;i<nStartPos.length;i++) q#-szZQ  
{ \.A~>=
:  
// output.writeLong(nPos); MEbx{XC  
output.writeLong(fileSplitterFetch.nStartPos); W xyQA:3s  
output.writeLong(fileSplitterFetch.nEndPos); ti)foam  
} e*e}
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output.close(); 2Av3.u8%u  
} `Y-uNJ'.N  
catch(IOException e){e.printStackTrace ();} /_?E0
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catch(Exception e){e.printStackTrace ();} >A|6kzC  
} h3D8eR.  
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//读取保存的下载信息（文件指针位置） 4`G":nE?We  
private void read_nPos() 4w^B
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{ e@s+]a8D-k  
try{ 6I(y`pJ  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Zr_{Z@IpU  
int nCount = input.readInt(); MI|DOp  
nStartPos = new long[nCount]; C_?L$3 U0  
nEndPos = new long[nCount]; ]`&EB~K&NY  
for(int i=0;i<nStartPos.length;i++) *A`hKx  
{ |QJ!5nb  
nStartPos = input.readLong(); Z.$ncP0s  
nEndPos = input.readLong();  &(\z  
} 3=1aMQ  
input.close(); 6#On .Q  
} 0O?B!Jr]RM  
catch(IOException e){e.printStackTrace ();} ;Br8\2=$  
catch(Exception e){e.printStackTrace ();} EXg\a#4['  
} s,N%sO;  
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private void processErrorCode(int nErrorCode) l/`<iG%  
{ h{S';/=8  
System.err.println("Error Code : " + nErrorCode); E
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} x&tad+T  
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F'W{\4  
//停止文件下载 gpsEN(.w  
public void siteStop() too=+'<N</  
{ RyC]4QyC  
bStop = true; w"bQxS~$y  
for(int i=0;i<nStartPos.length;i++) gVsAz  
fileSplitterFetch.splitterStop(); 49~5U+x;  
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} vL{~?vq6  
} +q"d=  
//负责部分文件的抓取 Ec[=~>;n{l  
**FileSplitterFetch.java \y{Bnp5h  
*/ 9M:wUYHT  
package NetFox; HQK%Y2S  
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import java.io.*; \i}n1Qd  
import java.net.*; P49lE  
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public class FileSplitterFetch extends Thread { aG8}R~wH&  
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String sURL; //File URL @3c
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long nStartPos; //File Snippet Start Position ]nhLv!Co  
long nEndPos; //File Snippet End Position "wmQ,=  
int nThreadID; //Thread's ID -7*,}xV  
boolean bDownOver = false; //Downing is over nZhL  
boolean bStop = false; //Stop identical GptJQ=pV  
FileAccessI fileAccessI = null; //File Access interface [#kfl  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 'N)&;ADx-G  
{ cfMj^*I  
this.sURL = sURL; uI@:\Rss  
this.nStartPos = nStart; FEw51a+V  
this.nEndPos = nEnd; _+N*4  
nThreadID = id; Ku*@4#<L6h  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 !]&a/$U  
} aJ88U69  
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public void run() m.EI("n"J  
{ Gn#5zx#l  
while(nStartPos < nEndPos && !bStop) 5Az=)q4Q  
{ 7gfNe kr~W  
q-eC=!#}  
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try{ .
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URL url = new URL(sURL); X{P_HCd  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #+|{l*>  
httpConnection.setRequestProperty("User-Agent","NetFox"); !>Db  
String sProperty = "bytes="+nStartPos+"-"; SfyZ,0  
httpConnection.setRequestProperty("RANGE",sProperty); )TFaG[tj  
Utility.log(sProperty); VZ'[\3J  
[MdVgJ9'  
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InputStream input = httpConnection.getInputStream(); _-x|g~pV*  
//logResponseHead(httpConnection); }RYr)  
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! pR&&uG  
byte[] b = new byte[1024]; J"y
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int nRead; >B U0B  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) j1*'yvGM  
{ AcyiP   
nStartPos += fileAccessI.write(b,0,nRead); 6A;V[3  
//if(nThreadID == 1) HsGXb\  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); HhhN8t  
} OGh9^,v  
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Utility.log("Thread " + nThreadID + " is over!"); W~aVwO'(  
bDownOver = true; ^](sCE7  
//nPos = fileAccessI.write (b,0,nRead); Zk__CgS#  
} /T]2ZX>  
catch(Exception e){e.printStackTrace ();} H ifKa/}P8  
} qxf!]jm  
} K>l$Y#x}k  
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//打印回应的头信息 x5YW6R.<t  
public void logResponseHead(HttpURLConnection con) $[T^S  
{ ' 7+x,TszI  
for(int i=1;;i++) t*m04* }  
{ CeSr~Ikg|  
String header=con.getHeaderFieldKey(i); ynvU$}w ~'  
if(header!=null) Hgu$)yhlj  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); f <fa+fB  
Utility.log(header+" : "+con.getHeaderField(header));
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else ~ P"@^cq  
break; 6O bB/*h  
} {mrTpw  
} >8D!K0?E  
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public void splitterStop() d&4ve Lu  
{ M(KsLu1   
bStop = true; fz\C$[+u  
} K#_&}C^-jY  
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} -KhNsUQk  
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/* p:Ry F4{b2  
**FileAccess.java ayfR{RYi  
*//文件访问(定位，写) ~7+7{9g  
package NetFox; GPz0qK  
import java.io.*; _v bCC7Bf8  
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public class FileAccessI implements Serializable{ r&oR|-2hRk  
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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 /2l&D~d"  
RandomAccessFile oSavedFile; S[JeW  
long nPos; W
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public FileAccessI() throws IOException  a?S5 =  
{ E-IVv  
this("",0); :+NZW9_  
} S"'0lS   
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public FileAccessI(String sName,long nPos) throws IOException u^|c_5J(  
{ $9+|_[ ]v.  
oSavedFile = new RandomAccessFile(sName,"rw"); FlGU1%]m  
this.nPos = nPos; pqe7a3jr  
oSavedFile.seek(nPos); |eykb?j`  
} k-IL%+U  
vF@hg)A  
IR;l{q&`  
public synchronized int write(byte[] b,int nStart,int nLen) vZ,DJ//U,  
{ Rd'P\  
int n = -1; Gu+9R>  
try{ EQI9J#;+  
oSavedFile.write(b,nStart,nLen); X-LCIT|1  
n = nLen; /By:S/[1pL  
} |y9(qcKn$  
catch(IOException e) &H8wYs  
{ [As9&]Bv5  
e.printStackTrace (); F-AU'o *  
} ~MWI-oK  
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return n; TOapq9B]  
} -p.c8B  
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} ' ` _TFTO  
4> k"$l/:  
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/* L$L/5/  
**SiteInfoBean.java yPY}b_W  
*/ `-t8ag3  
package NetFox; (P!r^87  
DW( /[jo\  
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public class SiteInfoBean { %,T=|
5  
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private String sSiteURL; //Site's URL F>Pr`T?>  
private String sFilePath; //Saved File's Path OfG/7pw5%B  
private String sFileName; //Saved File's Name SR%k|YT  
private int nSplitter; //Count of Splited Downloading File :o~]FVf  
aVB/CoM9  
$UNC0(4  
public SiteInfoBean() mtU{d^B  
{//nSplitter的缺省值为5 {zX]41T  
//default value of nSplitter is 5 Fn>KdoByN  
this("","","",5); )<Fq}Q86  
} 4)"S/u  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) UQZl:DYa  
{ [Ef6
@  
sSiteURL= sURL; QB uX#bDV  
sFilePath = sPath; 5(zdM)Y7  
sFileName = sName; 
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this.nSplitter = nSpiltter; |I[/Fl:  
"; 1@f"kw  
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} d1P|v( `S9  
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public String getSSiteURL() 3rVfBz  
{ (E;+E\E  
return sSiteURL; Ez8k.]q
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} *+OS;R1<  
|`ya+/ff+  
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public void setSSiteURL(String value) OZc4 -5  
{ }y%c.  
sSiteURL = value; J>l?HK  
} |v:oLgUdH  
)J*M{Gm6i  
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public String getSFilePath() ]d67 HOyK  
{ 1rx,qfCq  
return sFilePath; 2&"qNpPtE  
} 7}:+Yx
 
1 |  
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public void setSFilePath(String value) SJB^dI**/d  
{ (C;Q<  
sFilePath = value; Rh}}8 sv  
} H
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public String getSFileName() 6r|=^3{  
{ W#)X@TlE  
return sFileName; F r!FV4  
} P_4E<"eK  
5JHWt<n{P  
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public void setSFileName(String value) 7u{V1_n1  
{ qnCjNN  
sFileName = value; WBD?|
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} He,,bq  
@R-11wP)M  
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public int getNSplitter() OlB
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{ dz?On\66  
return nSplitter; M8Vc
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} h!@7'Q  
ollsB3]]  
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public void setNSplitter(int nCount) @@j:z;^|  
{ "OwK-  
nSplitter = nCount; ]5K+W  
} /GVjesN  
} cZJ5L>ox  
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tLi91)oG  
/* g<@Q)p*ow  
**Utility.java ),CKuq>  
*/ ? cXW\A(  
package NetFox; /IN#1I!K  
5 w(nttYH  
HKr}"`I.  
public class Utility { 43x2BW&&  
Lb)rloca  
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public Utility() tKS[  
{ _RzFh  
dQ:F5|p  
9
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} KF6C=,Yc%  
~o#mX?'7  
//线程睡眠 NT0n[o^  
public static void sleep(int nSecond) ]J[d8S5  
{ S)g:+P  
try{ Fgi`g{N  
Thread.sleep(nSecond); Pz34a@%"  
} =[8K#PZ$w  
catch(Exception e) _P=+\[|y  
{ tAE(`ow/Ur  
e.printStackTrace (); 5JhvYsf3_  
} !ej]'>V,X  
} O2\(:tvw  
~Th,<w*o  
//日志 mogmr  
public static void log(String sMsg) lP*n%Pn)  
{ m";..V  
System.err.println(sMsg); 9Vqy<7i1  
} (BFwE@1"  
~;?<OOt|wG  
tu Y+n2  
public static void log(int sMsg) }% f7O  
{ 0 zK{)HZ  
System.err.println(sMsg); q8&l%-d`  
} %59uR}\  
} Rw%% 9  
h}!9?:E  
x&*f5Y9hCi  
/* =w}JAEE|(i  
**TestMethod.java g0bYO!gCr  
*/ gs;^SRE I  
package NetFox; ymyzbE  
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public class TestMethod { hVmnXT 3Z  
&oMWs]0  
a/\{NHs6"5  
public TestMethod() }^iqhUvT F  
{ ///xx/weblogic60b2_win.exe *2u~5Kc<  
try{ BGBHA"5fz  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); );%H;X+x  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); _crhBp5@T3  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ka!v(j{E  
fileFetch.start(); ,5"(m?[m  
} aUzCKX%>C  
catch(Exception e){e.printStackTrace ();} bq9w@O  
tH)jEY9  
(bQ3:%nD  
} njf\fw_  
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&n )MGg1%  
public static void main(String[] args) &:g:7l]g  
{ (z>t4(%\  
new TestMethod(); i
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} ^l|b>z"0ao  
} B Z|A&;  
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