http断点续传简单实现（java)

/* u~b;m  
**SiteFileFetch.java -u+@5K;^Y  
*/ 2tPW1"M.n  
package NetFox; %-9?rOr  
import java.io.*; n!Hj4~T0  
import java.net.*; Z*uv~0a>9Q  

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public class SiteFileFetch extends Thread { AzFd#P  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Aw?i6d  
long[] nStartPos; //开始位置 $~)BO_;o  
long[] nEndPos; //结束位置 fv@mA--  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 7Yv1et |  
long nFileLength; //文件长度 v=m!$~  
boolean bFirst = true; //是否第一次取文件 .+ezcG4q  
boolean bStop = false; //停止标志 9mA6nmp  
File tmpFile; //文件下载的临时信息 HrOq>CSR  
DataOutputStream output; //输出到文件的输出流 HKB?G~  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） zEM c)  
public SiteFileFetch(SiteInfoBean bean) throws IOException (U_`
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{ {*yFTP"93  
siteInfoBean = bean; ws/e~ T<c  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); {"v~1W)  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); FZFYwU\~.L  
if(tmpFile.exists ()) QK~44;LVIJ  
{ FS'|e?WU  
bFirst = false; )NF5,eD  
read_nPos(); b@v_db]|t.  
} q8Jhs7fv  
else "rl(%~Op  
{ "aL.`^.  
nStartPos = new long[bean.getNSplitter()]; x."R_>  
nEndPos = new long[bean.getNSplitter()]; {beu  
} D;1?IeS  
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} I8x,8}o>V  
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public void run() ?T1vc  
{ qg2fTe  
//获得文件长度 og[cwa_  
//分割文件 % _.kd"  
//实例FileSplitterFetch *;ehSg9  
//启动FileSplitterFetch线程 xF8U )j!  
//等待子线程返回 *VX"_C0Jy=  
try{ \=1$$EDS9  
if(bFirst) s!IX3rz  
{ APgjT';P^  
nFileLength = getFileSize(); B3^F $6=  
if(nFileLength == -1) T0;8koj^_  
{ %~e+H|  
System.err.println("File Length is not known!"); )k^y<lC2a  
} '^|u\$&U  
else if(nFileLength == -2) M&[bb $00j  
{ <(Rbu2_  
System.err.println("File is not access!"); :~^_*:  
} vZiuElxKi  
else K0aT(Rc e  
{ mAM:Q*a'  
for(int i=0;i<nStartPos.length;i++) 9}|x N8  
{ 5FJ(x:k?z  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); eG_@WLxwD  
} jd.{J{o  
for(int i=0;i<nEndPos.length-1;i++) PQd*)6K:A  
{ wPE\?en  
nEndPos = nStartPos[i+1]; 88&M8T'AP  
} ]qd$rX  
nEndPos[nEndPos.length-1] = nFileLength; &wa2MNCG8  
} ,*kh{lJ  
} tE8aL{<R  
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//启动子线程 @=ro/.  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; +$YHdgZ.  
for(int i=0;i<nStartPos.length;i++) 7gc?7TM  
{ ZX8AB  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), "Cz0r"N  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Jn&^5,J]F8  
nStartPos,nEndPos,i); bu8AOtY9E-  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Z35(f0b  
fileSplitterFetch.start(); yE#.Q<4  
} EJW}&e/  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 4{QD: D(D  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); >Jk]=_%  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ^O3i)GO  
nEndPos = " + nFileLength); p:NIRs  
// fileSplitterFetch[nPos.length-1].start(); GYt|[GC  
)61X,z  
/ q| o  
//等待子线程结束 cC*H.N  
//int count = 0; )Drif\FF)  
//是否结束while循环 0z$::p$%u  
boolean breakWhile = false; i
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while(!bStop) 9vckQCLM  
{ g)1`A24  
write_nPos(); sj3[ny;b  
Utility.sleep(500); *{("T  
breakWhile = true; Js<DVe,  
/,,IM/(6^  
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for(int i=0;i<nStartPos.length;i++) O)!S[5YI  
{ 5c\dm  
if(!fileSplitterFetch.bDownOver) `]=0oDG:1!  
{ 'Rb tcFb  
breakWhile = false; QuIZpP=  
break; hb<cynY  
} OWc~=Cr  
} I}+9@d  
if(breakWhile) x }@P  
break; 3wMnTT"At  
LP'wL6#  
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//count++; ]1 jhy2j  
//if(count>4) \4KV9wm  
// siteStop(); aH_0EBR
c  
} CB0p2WS_  

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System.err.println("文件下载结束！"); {kghZur  
} Vb)NWXmyu  
catch(Exception e){e.printStackTrace ();} aL&nD1f=!-  
}  20]p<  
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//获得文件长度 w$Z%RF'p  
public long getFileSize() e^}@X[*'#  
{ qP$)V3
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int nFileLength = -1; vSy[lB|)24  
try{ :Y|[
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URL url = new URL(siteInfoBean.getSSiteURL()); r&+w)U~  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); <1#hX(Q  
httpConnection.setRequestProperty("User-Agent","NetFox"); 81H9d6hqcD  
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int responseCode=httpConnection.getResponseCode(); N9s+Tm  
if(responseCode>=400) L_tjclk0J  
{ \YSprXe  
processErrorCode(responseCode); 1H?I?IT30  
return -2; //-2 represent access is error },@ex  
} fDRG+/q(+  
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String sHeader; Yd(<;JKF[  
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for(int i=1;;i++) \&l@rMD3s  
{ B3<sSe8L0  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 8F&Y;  
//Utility.log(in.readLine()); 4peRbm  
sHeader=httpConnection.getHeaderFieldKey(i); /P
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if(sHeader!=null) `2/V.REX$h  
{ yJ="dEn>i"  
if(sHeader.equals("Content-Length")) dZox;_b  
{ [FZq'E"87  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); TPs ]n7]:  
break; ,M~> t7+  
} dvM%" k  
} phQ{<wzwp  
else s\< @v7A  
break; kE:{#>[Uz  
} OIIA^QyV  
} 6Jq3l_  
catch(IOException e){e.printStackTrace ();} I
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catch(Exception e){e.printStackTrace ();} 3~{0X-  
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4  
Utility.log(nFileLength); PuhvJHT  
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return nFileLength;
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} Y^nm{;G+  
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//保存下载信息（文件指针位置）  d0i|^  
private void write_nPos() lwz\"8  
{ a;v4R[lQ  
try{ F+ 7*SImv6  
output = new DataOutputStream(new FileOutputStream(tmpFile)); +&dkJ 4g[  
output.writeInt(nStartPos.length); h?H|)a<^9  
for(int i=0;i<nStartPos.length;i++) O~v~s 'c&  
{ :[CEHRc7x  
// output.writeLong(nPos); mlPvF%Ba  
output.writeLong(fileSplitterFetch.nStartPos); )TEm1\  
output.writeLong(fileSplitterFetch.nEndPos); 80`$F{xcX  
} f7|Tp
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output.close(); "LSzF_mK  
} -w>ss&  
catch(IOException e){e.printStackTrace ();} d"n"A?nXh  
catch(Exception e){e.printStackTrace ();} (tX)r4VU  
} 0yv
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//读取保存的下载信息（文件指针位置） 1J72*`4OK  
private void read_nPos() *Hi}FI  
{  Bnk'  
try{ >t<\zC|~w  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 6`vW4]zu  
int nCount = input.readInt(); m;A[2 6X  
nStartPos = new long[nCount]; 3Fxr=  
nEndPos = new long[nCount]; E NCWOj  
for(int i=0;i<nStartPos.length;i++) T--%UZD]W  
{ awI{%u_(nA  
nStartPos = input.readLong(); CUHT5J*sY  
nEndPos = input.readLong(); bdY:-8!3  
} nt+OaXe5D  
input.close(); ~A1!!rJX  
} aj,o<J
  
catch(IOException e){e.printStackTrace ();} 1;DRcVyS+  
catch(Exception e){e.printStackTrace ();} >x3lA0m  
} B^]PKjLNZ  
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private void processErrorCode(int nErrorCode) gWoUE7.3`  
{ ~ rQ,%dH  
System.err.println("Error Code : " + nErrorCode); ?Pa(e)8\  
} Y9>92#aME  
'n ^,lXWB  
!nvg:$.&  
//停止文件下载 x}nBUq:  
public void siteStop() 3kk^hvB+f  
{ 15q^&l[Q  
bStop = true; )TKn5[<4  
for(int i=0;i<nStartPos.length;i++) (Li0*wRb  
fileSplitterFetch.splitterStop(); D
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} qv}ECQ  
} 77y+ik
 
//负责部分文件的抓取 N_S~&(I|  
**FileSplitterFetch.java RGs7Hc  
*/ .c~z^6x  
package NetFox; D/~1?p  
K!.t}s.t  
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import java.io.*; l)dE7$H  
import java.net.*; $B_%MfI  
>;'0ymG.`  
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public class FileSplitterFetch extends Thread { Je6w
io-4  
qT!lq  
1kw*Q:  
String sURL; //File URL )dqNN tS  
long nStartPos; //File Snippet Start Position mJ=V<_  
long nEndPos; //File Snippet End Position pjX=:K|  
int nThreadID; //Thread's ID KYtCN+vsG  
boolean bDownOver = false; //Downing is over C}pm>(F~  
boolean bStop = false; //Stop identical <R;wa@a>  
FileAccessI fileAccessI = null; //File Access interface LiV&47e*>  
]X77?Zz9  
-{k8^o7$  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException N0Y4m_dm*  
{ y.J>}[\&x  
this.sURL = sURL; Ul9^"o  
this.nStartPos = nStart; K%+4M#jj5  
this.nEndPos = nEnd; Q}OloA(+  
nThreadID = id; op5`#{  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 >e R^G5rn;  
} q(:L8nKT]  
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public void run() LUId<We  
{ [}ja\!P  
while(nStartPos < nEndPos && !bStop)  +:-xV  
{ WV.hQX9P  
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try{ ^@O7d1&y  
URL url = new URL(sURL); )!\6 "{  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Xi) ;dcNJ  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'JJKnE zQ  
String sProperty = "bytes="+nStartPos+"-"; E V)H>kM  
httpConnection.setRequestProperty("RANGE",sProperty); #jrlNg4(  
Utility.log(sProperty); (C#0 ML  
>MN"87U6  
?%UiW7}j';  
InputStream input = httpConnection.getInputStream(); JJ ?'<)EF  
//logResponseHead(httpConnection); e4SS'0|  
7=^}{  
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byte[] b = new byte[1024]; o]Ne|PEpO  
int nRead; ]!"w?-h Si  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) rFpYlMct  
{ @4T
  
nStartPos += fileAccessI.write(b,0,nRead); GI/NouaNfm  
//if(nThreadID == 1) ,++HiYOG}e  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8R!-,I"$  
} g^(gT  
c{I]!y^!  
]"uG04"Vk  
Utility.log("Thread " + nThreadID + " is over!"); *>:phs~r{  
bDownOver = true; 8Iw)]}T'  
//nPos = fileAccessI.write (b,0,nRead); GZu12\0nZ  
} |<h}'  
catch(Exception e){e.printStackTrace ();} $V!.z%Vgf  
} XV]xym~  
} 8+}rm6Y+  
<3BGW?=WP  
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//打印回应的头信息 x0JW  
public void logResponseHead(HttpURLConnection con) bRy(`  
{ q%])dZ!lE  
for(int i=1;;i++) #<b\BqYG  
{ 5)T[ha77u  
String header=con.getHeaderFieldKey(i); [;Lgbgt3f  
if(header!=null) V<S6a
  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); G&^8)S@1  
Utility.log(header+" : "+con.getHeaderField(header)); <i</pA  
else !>> A@3  
break; %K|f,w=m  
} $.4A?,d  
} L<@*6QH  
 5)'Y\~2  
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public void splitterStop() C0N}B1-MU  
{ O[t?*m1/  
bStop = true; GkI'.  
} XdCP!iq*8  
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b.RU%Y#>\  
} /Tm+&Jd  
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\]f+{d-&  
/* 
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**FileAccess.java {:!>Y1w>  
*//文件访问(定位，写) gR# k'  
package NetFox; M9R'ONYAa  
import java.io.*; Eqz|eS*6  
j}//e%$a  
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public class FileAccessI implements Serializable{ A)"L+Yu5  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 U52V1b  
RandomAccessFile oSavedFile; L}rZ1wV6  
long nPos; 27ZqdHd  
 FNH)wk  
nL=+`aq_  
public FileAccessI() throws IOException ]dNNw`1\V  
{ d=^QK{8  
this("",0); Pb?vi<ug+  
} :FI D,  
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public FileAccessI(String sName,long nPos) throws IOException ]#f%Dku.m  
{
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oSavedFile = new RandomAccessFile(sName,"rw"); lb't
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this.nPos = nPos; C_Q3
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oSavedFile.seek(nPos);
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} JH]S'5X8K  
07:V[@'  
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public synchronized int write(byte[] b,int nStart,int nLen) r_$*euh@  
{ @,.D]43  
int n = -1; ?K7uy5Y  
try{ r6uN6XCM  
oSavedFile.write(b,nStart,nLen); u
:|^L]{  
n = nLen; qH4|k2Lm  
} g&y (-  
catch(IOException e) <A Hzs  
{ zO"De~[9  
e.printStackTrace (); k*N!U[]  
} q`r| DcN~  
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. KLEx]f.  
return n; PF/K&&9}
 
} #)~u YQ  
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}
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/*
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**SiteInfoBean.java D#1R$4M=  
*/ Og%Y._  
package NetFox; SgxrU&:
:  
i%.NP;Qq]M  
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public class SiteInfoBean { 7BU7sQjs  
?HPAX  
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private String sSiteURL; //Site's URL :5&D6  
private String sFilePath; //Saved File's Path 37kFbR@x  
private String sFileName; //Saved File's Name li3,6{S
#  
private int nSplitter; //Count of Splited Downloading File 46NuT]6/4  
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o 7kg.w|  
public SiteInfoBean() #&kj>  
{//nSplitter的缺省值为5 /J-'[Mc'D[  
//default value of nSplitter is 5 *h0D,O"0  
this("","","",5);
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} 1i$VX|r  
7\%JJw6h  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) HBe*wkPd  
{ Sk+XBX(}  
sSiteURL= sURL; g=nb-A{#  
sFilePath = sPath; _:Xmq&<W  
sFileName = sName; Nf!N;Cy?  
this.nSplitter = nSpiltter; i!}k5k*Z  
[(x<2MTj  
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} %k4Qx5`?d  
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public String getSSiteURL() b]z_2h~`  
{ >D!R)W`  
return sSiteURL; .+(
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} F\+AA  
50Gr\  
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public void setSSiteURL(String value) ~wuCa!!A  
{ EQlb:;j  
sSiteURL = value; \54B  
} %dPk,Ylz  
&J2UAmB  
s9sl*1n1m`  
public String getSFilePath() FtyT:=Kpc  
{ 2LUsqL\m}.  
return sFilePath; N2s"$Ttq  
} }UsH#!9.  
%pq.fZI  
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public void setSFilePath(String value) x
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{ Ty
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sFilePath = value; hT-^1:N  
} _Sd^/jGpU  
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|OCiq|#  
public String getSFileName() <e BmCrJ  
{ {7m2vv?Z  
return sFileName; h#4n  
} {rMf/RAE  
36OQHv;&  
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public void setSFileName(String value) xK_UkB-$i  
{ z9IW&f~~P  
sFileName = value; u]
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} c>D~MCNxg  
UZs '[pm)  
Jkj
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public int getNSplitter() kl:/PM^  
{ | CFG<]  
return nSplitter; y%%VJ}'X!  
} >gzM-d  
[?7QmZK  
:1qLRr  
public void setNSplitter(int nCount) K!CVS7  
{ 5B:"$vC{=  
nSplitter = nCount; #Q7:Mu+  
} w~Q\:<x&~Z  
} m-uXQS^@G  
Vc9Bg2f5  
":+d7xR?o  
/* </_QldL_  
**Utility.java ,H6P%  
*/ W'@G5e  
package NetFox; H.l0kBeG  
Q +l{> sL  
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public class Utility { E va&/o?P|  
%TN$   
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public Utility() 9U<WR*H  
{ [VXQ&  
Ao?b1VYy/  
@xo8"kl  
} 'L O3[G{  
BTr oe=R  
//线程睡眠 bTeuOpp  
public static void sleep(int nSecond) I(VqtC:K.  
{ axC{azo|  
try{ 'vVt^h2  
Thread.sleep(nSecond); }\<=B%{  
} *3Lo[GE>  
catch(Exception e) ;q-c[TZC  
{ -5og)ZGVUA  
e.printStackTrace (); ^jL)<y4`  
} ?qs
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} hd'
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_Ml?cT/J.O  
//日志 Ynf "g#(  
public static void log(String sMsg)
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{ aOg9Dqtg)f  
System.err.println(sMsg); YvG$2F|_)  
}
&J/!D#  
Cw:|(`
9  
~_;.ZZ-H]  
public static void log(int sMsg) qmpT G:+  
{ AoGpM,W]5  
System.err.println(sMsg); _hV34:1F  
} _)vX_gCi  
} ]vcT2lr]  
NaoOgZ?  
_`=qc/-0  
/* V#,|#2otZ  
**TestMethod.java Ma?uB8o+~  
*/ Z*3RI5)dx  
package NetFox; W!ug^2"  
r:o9:w:  
E^n!h06~G  
public class TestMethod { @dK_w'W  
]v:,<=S  
TVvE0y(9  
public TestMethod() 'g<{l&u  
{ ///xx/weblogic60b2_win.exe [r7Hcb  
try{ .6[8$8c  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); .sit5
BX  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); )M7yj O!  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Jityb}Z"  
fileFetch.start(); DHn\ =M  
} w;$elXP|  
catch(Exception e){e.printStackTrace ();} dAG@'A\f  
a{7*um  
+ rB3\R"d  
} p Cx_[#DrP  
EK>x\]O%T  
`>KNa"b%$  
public static void main(String[] args) E5S(1Z}]p{  
{ T)22P<M8  
new TestMethod(); FB?V<x  
} uh9b!8  
} V 7~9z\lW  
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