http断点续传简单实现（java)

/* 4{U T!WIi  
**SiteFileFetch.java 9@(PWz=`?  
*/ E)5\i-n  
package NetFox; *20jz<  
import java.io.*; EoR}Af  
import java.net.*; IqaT?+O\?r  
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public class SiteFileFetch extends Thread { t
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SiteInfoBean siteInfoBean = null; //文件信息Bean  5h=}j  
long[] nStartPos; //开始位置 %~H-)_d20  
long[] nEndPos; //结束位置 DFB@O|JL  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 a`E#F]Z  
long nFileLength; //文件长度 qs6]-  
boolean bFirst = true; //是否第一次取文件 p Z|V 3  
boolean bStop = false; //停止标志 x_N'TjS^{  
File tmpFile; //文件下载的临时信息 x;P_1J%Q  
DataOutputStream output; //输出到文件的输出流 .\ULbN3Z  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） XFHYQ2ME2  
public SiteFileFetch(SiteInfoBean bean) throws IOException yiXSYD  
{ S]e|"n~@  
siteInfoBean = bean; mP~QWx![N  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Wd
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ;>EM[u  
if(tmpFile.exists ()) >=I|xY,  
{ #4Rx]zW^%  
bFirst = false; TCwFPlF|  
read_nPos(); o4F2%0gJ  
} +s,=lL  
else !&y8@MD15  
{ ~*&H$6NJS  
nStartPos = new long[bean.getNSplitter()]; NqazpB*  
nEndPos = new long[bean.getNSplitter()]; w7.V6S$Ga  
} #Yj1w  
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} /!yU!`bY  
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public void run() Q^9_'t}X  
{ )Pa'UGY  
//获得文件长度 ah4N|zJ>v  
//分割文件 {Qf=G|Ah  
//实例FileSplitterFetch H7&8\FNa  
//启动FileSplitterFetch线程 FF`T\&u  
//等待子线程返回
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try{ m{Wu" ;e  
if(bFirst) Y1W1=Uc uk  
{ urs,34h  
nFileLength = getFileSize(); ~tS Z%q  
if(nFileLength == -1) J9--tJ?[>o  
{ G#q@v(_b  
System.err.println("File Length is not known!"); TTX5EDCrC  
} ok"
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else if(nFileLength == -2) Y|F9}hj(  
{ I#Y22&G1  
System.err.println("File is not access!"); E1aHKjLQ  
} O_muD\  
else njB;&N)I  
{ W dK #ZOR  
for(int i=0;i<nStartPos.length;i++) ?DS@e@lx  
{
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); (?1y4M  
} ouvA~/5  
for(int i=0;i<nEndPos.length-1;i++) %ufN8w!p  
{ Af~$TyX  
nEndPos = nStartPos[i+1]; -e"H ^:  
} 6xx<Y2@  
nEndPos[nEndPos.length-1] = nFileLength; ~~/|dh5  
} 9IdA%RM~mH  
}
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//启动子线程 HT
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; vFzRg
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for(int i=0;i<nStartPos.length;i++) PfAgM1  
{ 7FP*oN?  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $D~0~gn~  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 6m/r+?'  
nStartPos,nEndPos,i); U/66L+1  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [x=s(:qy  
fileSplitterFetch.start(); :(U,x<>  
} I;,77PxD  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), eH'av}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 3)t.p>VgO  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Fj8z  
nEndPos = " + nFileLength); v|_K/|  
// fileSplitterFetch[nPos.length-1].start(); q"CVcLi9  
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//等待子线程结束 r..iko]T  
//int count = 0; *2>&"B09`  
//是否结束while循环 ;>U2|>5V  
boolean breakWhile = false; '2A)}
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while(!bStop) 

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{ 0I-9nuw,^;  
write_nPos(); ^&9zw\x;z  
Utility.sleep(500); Hs;4lSyUO  
breakWhile = true; ^ glri$m  
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for(int i=0;i<nStartPos.length;i++) j1Y~_  
{ L Tm2G4+]  
if(!fileSplitterFetch.bDownOver) R"/GQ`^AqA  
{ 59 T8r  
breakWhile = false; {Y(zd
[  
break; yM6pd U]i  
} nK1Slg#U  
} >mbHy<<  
if(breakWhile) a Yg6H2Un  
break; 1sy[@Q2b  
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//count++; gMi
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//if(count>4) ]\-A;}\e  
// siteStop(); ch*8B(:  
} &@X<zWg  
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System.err.println("文件下载结束！"); h"B+hu  
} \Gef \  
catch(Exception e){e.printStackTrace ();} hk;5w{t}}  
} f=+
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;}I:\P  
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//获得文件长度 c8 )DuJ#U  
public long getFileSize() @W.S6;GA\  
{ F>Ah0U0  
int nFileLength = -1; z#9aP&8Q  
try{  h},IF  
URL url = new URL(siteInfoBean.getSSiteURL()); Po+.&7F  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); X;+sUj8  
httpConnection.setRequestProperty("User-Agent","NetFox"); ~Py`P'+  
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int responseCode=httpConnection.getResponseCode(); P_^ +A  
if(responseCode>=400) L?b~k=  
{ w?PkO p  
processErrorCode(responseCode); Qab>|eSm  
return -2; //-2 represent access is error Ve$o}h-  
} J'6PmPzY|  
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String sHeader; l ~"^7H?4e  
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for(int i=1;;i++) ;$,U~0  
{ 7DogM".}~Q  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 5+4IN5o]=  
//Utility.log(in.readLine()); >a<.mU|#  
sHeader=httpConnection.getHeaderFieldKey(i); Pjf"CW+A  
if(sHeader!=null) wq`s-qZu  
{ }^WdJd]P  
if(sHeader.equals("Content-Length")) RF$eQzW  
{ d UE,U=  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); .<0ye_S'y  
break; 98c(<  
} =`oCLsz=  
} )bL'[h
 
else l+K'beP  
break; wQl ,  
} tPWLg),  
} &GO}|W  
catch(IOException e){e.printStackTrace ();} /|m2WxK)  
catch(Exception e){e.printStackTrace ();} <Xhm`rH  
];$L &5^  
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Utility.log(nFileLength); XAKs0*J>  
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return nFileLength; .&iawz  
} a#(?P.6  
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//保存下载信息（文件指针位置） |)DGkOtd  
private void write_nPos() HXC
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{ ITXa&5D  
try{ fSj5ZsO  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 7vKK%H_P  
output.writeInt(nStartPos.length); F@jZ
ho  
for(int i=0;i<nStartPos.length;i++) VR8-&N  
{ V*;(kEqj  
// output.writeLong(nPos); GT.,  
output.writeLong(fileSplitterFetch.nStartPos); np^N8$i:n  
output.writeLong(fileSplitterFetch.nEndPos); dm0R[[7  
} yx8z4*]kH  
output.close(); wo{gG?B  
} `:fZ)$sY  
catch(IOException e){e.printStackTrace ();}  :A_@,Q  
catch(Exception e){e.printStackTrace ();} ,Ks8*;#r  
} WM$ MPs  
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//读取保存的下载信息（文件指针位置） ;u ({\K
 
private void read_nPos() Zd%k*BC  
{ =%K;X\NB  
try{ zV37$Hb  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); :gibfk]C  
int nCount = input.readInt(); /)>3Nq4Zx  
nStartPos = new long[nCount]; Y;M|D'y+  
nEndPos = new long[nCount]; 1z4OI6$Af  
for(int i=0;i<nStartPos.length;i++) BsDn5\q  
{ [-K&R  
nStartPos = input.readLong(); ^ig' bw+WS  
nEndPos = input.readLong(); h 0Q5-EA  
} 9d659iC  
input.close(); e\l7Iu  
} UYJZYP%r  
catch(IOException e){e.printStackTrace ();} 13=AW  
catch(Exception e){e.printStackTrace ();} kd(8
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} `wEb<H  
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private void processErrorCode(int nErrorCode) g}{aZ$sta  
{ RWZSQ~  
System.err.println("Error Code : " + nErrorCode); ;7V%#-  
} L|7R9+ZG  
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//停止文件下载 g3/W=~r  
public void siteStop() 83\pZ1>)_  
{ } 9Eg=%0v  
bStop = true; B
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for(int i=0;i<nStartPos.length;i++) u'DRN,h+  
fileSplitterFetch.splitterStop(); xGg )Y#  
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} J/aC}}5D  
} CYP q#rd  
//负责部分文件的抓取 .@U@xRu7|  
**FileSplitterFetch.java _7L-<  
*/ ?Ep [M:,q  
package NetFox; K=k"a  
"?xHlYj@+  
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import java.io.*; /nNN,hz  
import java.net.*; J=I:CD%  
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public class FileSplitterFetch extends Thread { ?P`
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String sURL; //File URL \&3+D8H>n  
long nStartPos; //File Snippet Start Position zP8lN(LA  
long nEndPos; //File Snippet End Position 5x4yyb'  
int nThreadID; //Thread's ID Id .nu/  
boolean bDownOver = false; //Downing is over pJ"qu,w  
boolean bStop = false; //Stop identical IueFx u  
FileAccessI fileAccessI = null; //File Access interface )23H1  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 7'V@+5
 
{ />pI8 g<  
this.sURL = sURL; _op}1   
this.nStartPos = nStart; 6iE<T&$3P  
this.nEndPos = nEnd; 9IfmW^0  
nThreadID = id; ~KX/ Ai  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 q ^N7I@Y  
} l4YJ c  
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public void run() mnX2a  
{ :KP@RZm  
while(nStartPos < nEndPos && !bStop) giw &&l=_  
{ hRCJv#]HC  
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try{ _9Te!gJ4_#  
URL url = new URL(sURL); WO>nIo5Y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); D8?Vn"  
httpConnection.setRequestProperty("User-Agent","NetFox"); s$`0yGmQ  
String sProperty = "bytes="+nStartPos+"-"; D'PI1 0t  
httpConnection.setRequestProperty("RANGE",sProperty); c]o'xd,T8\  
Utility.log(sProperty); {]@= ijjf  
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InputStream input = httpConnection.getInputStream(); V5>B])yQ  
//logResponseHead(httpConnection); )'cMYC  
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@:vwb\azVD  
byte[] b = new byte[1024]; `kXs;T6&  
int nRead; y/7\?qfTk  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) xdt- ;w|  
{ Q\7h`d%)  
nStartPos += fileAccessI.write(b,0,nRead); Ie#Bkw'*  
//if(nThreadID == 1) vr6w^&[c^  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos);
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} p]+Pkxz]'  
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Utility.log("Thread " + nThreadID + " is over!"); 6 V=9M:  
bDownOver = true; I-(zaqp@  
//nPos = fileAccessI.write (b,0,nRead); SZ'R59Ee<  
} flbd0NB  
catch(Exception e){e.printStackTrace ();} ;$wVu|&  
} !?h;wR  
} ^k">A:E2  
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d^ 8ZeC#  
//打印回应的头信息 u `6:5k  
public void logResponseHead(HttpURLConnection con) !z3jTv  
{ })Vi  
for(int i=1;;i++) %l[( Iw  
{ >}i E(  
String header=con.getHeaderFieldKey(i); :':s@gqr  
if(header!=null) n;Vs_u/Nx  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); p}~JgEE  
Utility.log(header+" : "+con.getHeaderField(header)); SoK iE  
else VjZ|$k  
break; "@0]G<H  
} 7;wd(8  
} yN(%-u"  

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public void splitterStop() &d^m 1  
{ S;#'M![8  
bStop = true; /@TF5]Ri  
} je=a/Y=%U{  
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} ,w4V?>l  
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/* $B5aje}i  
**FileAccess.java r52gn(,  
*//文件访问(定位，写) 6mxfLlZ  
package NetFox; 00~mOK;1  
import java.io.*; ~V1E0qdAE  
}N6.Uu5zI  
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public class FileAccessI implements Serializable{ e=m42vIB-  
RQ" ,3.R==  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ?J~_R1Z  
RandomAccessFile oSavedFile; ^o&. fQ*  
long nPos; Z o(rTCZX  
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u <v7;dF|s  
public FileAccessI() throws IOException ?J>  
{ 7?w*]  
this("",0); 6q.Uhe_B  
} dSV8q ,D  
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public FileAccessI(String sName,long nPos) throws IOException *#+An<iT ;  
{ z[qDkL  
oSavedFile = new RandomAccessFile(sName,"rw"); 3{sVVq5Y  
this.nPos = nPos; T'Dv.h  
oSavedFile.seek(nPos); [2M'PT3  
} T%*D~=fQ'  
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public synchronized int write(byte[] b,int nStart,int nLen) \d`h/tHk  
{ |[b{)s?x  
int n = -1; t!7-DF|N  
try{ ZyFjFHe+  
oSavedFile.write(b,nStart,nLen); z1X`o  
n = nLen; <*cikXS  
} LG#t<5y~  
catch(IOException e) {9.|2%a  
{ A#YrWW  
e.printStackTrace (); (V2fRv  
} 8XE7]&)];  
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return n; oE]QF.n#  
} -]M5wb2,  
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} NU2;X (z[  
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/* IyG}H}  
**SiteInfoBean.java c(s.5p ^  
*/ /aZ`[m2  
package NetFox; M[,@{u/  
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public class SiteInfoBean { k~1?VQ+?M  
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private String sSiteURL; //Site's URL &6nWzF  
private String sFilePath; //Saved File's Path ~oY^;/ j  
private String sFileName; //Saved File's Name \z(gqkc 6  
private int nSplitter; //Count of Splited Downloading File q^<?]8  
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public SiteInfoBean() Wg]Qlw`\|  
{//nSplitter的缺省值为5 5VU2[ \  
//default value of nSplitter is 5 Y`a3tO=Pd  
this("","","",5); {F.[&/A  
} nZYBE030  
/f;~X"!  
t
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) XU(eEnmom  
{ 4@ai6,<  
sSiteURL= sURL; o0KL5].  
sFilePath = sPath; ##"HF  
sFileName = sName; Oxd]y1  
this.nSplitter = nSpiltter; ]~3V}z,T*  
-6B4sZpzD  
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} +TDw+  
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public String getSSiteURL() &^Q/,H~S  
{ c\AfaK^KF  
return sSiteURL; ;u)I\3`*!  
} $*fMR,~t&  
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public void setSSiteURL(String value) P-"y3 ZE=  
{ 7zG_(83)K  
sSiteURL = value; [.wYdv35  
} xU`p|(SS-  
vy
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public String getSFilePath() Btcy)LRk  
{ /IMFO:c  
return sFilePath; 0n{=%Q  
} h~zT ydnH  
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public void setSFilePath(String value) %1+4_g9  
{ (SAs-  
sFilePath = value; Rnq7LG
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} )+9Uoe~6  
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public String getSFileName() {I't]Qj_e  
{ nAdf=D'P  
return sFileName; |&i<bqLw:  
} {"KMs[M  
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}@d@
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public void setSFileName(String value) \,0oX!<YY  
{ 2<}%kQ`  
sFileName = value; L~
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} h<<v^+m  
?4T-@~~*`=  
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public int getNSplitter() /N.U/
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{ 5`p.#  
return nSplitter; ;;/{xvQ.1  
} 
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p9-K_dw3X@  
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public void setNSplitter(int nCount) uQKT  
{ 63IM]J  
nSplitter = nCount; a9Zq
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} [(7S.5I  
} ]Zh%DQ  
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/* c@L< Z`u  
**Utility.java U|R_OLWAg  
*/ S{T >}'y  
package NetFox; ]3Sp W{=^(  
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public class Utility { /Lr.e
%  
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public Utility() >Cq<@$I2EB  
{ mj7#&r,1l  
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} E|shs=I  
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//线程睡眠 ) ;Y;Q  
public static void sleep(int nSecond) iuul7VR-%  
{ Dk51z@  
try{ 'i|YlMFIg  
Thread.sleep(nSecond); >Y@H4LF;1x  
} M x"\5i  
catch(Exception e) z},# ~L6$q  
{ jq0O22 -R  
e.printStackTrace (); W: z;|FF  
} Q\sK"~@3  
} ]JQULE)  
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//日志 =~LJ3sIX  
public static void log(String sMsg) Z*6IW7#  
{ ":N9(}9  
System.err.println(sMsg); 9QJyZ  
} 4Ftu  
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public static void log(int sMsg) w7&A0M  
{ k$:|-_(w  
System.err.println(sMsg); t4-[Z$n5  
} TIg3`Fon  
} B^}yo65I  
{R{=+2K!|k  
[0("Q;Ec[j  
/* XW92gI<O  
**TestMethod.java 9H1rO8k  
*/ +:/%3}
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package NetFox; <
I``&>  
as=fCuJ  
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public class TestMethod { {?7Uj  
w_VP J  
0JujesUw(  
public TestMethod() Zx>=t
x}  
{ ///xx/weblogic60b2_win.exe Q22 GIr  
try{ +&H4m=D-#a  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); E' uZA  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ;}p  
SiteFileFetch fileFetch = new SiteFileFetch(bean);
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fileFetch.start(); t sRdvFFq  
} A^SgI-y|  
catch(Exception e){e.printStackTrace ();} E92-^YY  
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} uCB=u[]y4  
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public static void main(String[] args) `uTmw^pZX  
{ 1G`Pmh@  
new TestMethod(); X2"/%!65{  
} >/6 _ ^  
} {id4:^u&;  
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