http断点续传简单实现（java)

/* ;_Z[' %  
**SiteFileFetch.java XdxSi"+  
*/ 1'"TO5  
package NetFox; Th>ff)~e  
import java.io.*; sw$$I~21  
import java.net.*; I$w:
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public class SiteFileFetch extends Thread { w=feXA3-S  
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SiteInfoBean siteInfoBean = null; //文件信息Bean N(=Z4Nk5  
long[] nStartPos; //开始位置 ap|$8G  
long[] nEndPos; //结束位置 %UokR"  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 1E]TH/JK  
long nFileLength; //文件长度 * faG0le  
boolean bFirst = true; //是否第一次取文件 <Po$|$_~  
boolean bStop = false; //停止标志 ft><Ql3  
File tmpFile; //文件下载的临时信息 f )Ef
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DataOutputStream output; //输出到文件的输出流 KO3X)D<3  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） vA&MJD{  
public SiteFileFetch(SiteInfoBean bean) throws IOException Jwt_d}ns  
{ w9]HJ3qi  
siteInfoBean = bean; 2U.'5uA"L  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ;G|#i?JJ  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); '
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if(tmpFile.exists ()) x,:DL)$1  
{ 5~GH*!h%;  
bFirst = false; Dlqvz|X/  
read_nPos(); "cDMFu  
} #Q'j^y7=z  
else `b?o%5V2x  
{ S}/5W  
nStartPos = new long[bean.getNSplitter()]; >7,?X_:A-1  
nEndPos = new long[bean.getNSplitter()]; 5-?*Boi>i  
} My<.^~  
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} 1=z6m7@'-  
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public void run() WiiAIv&  
{ *!m(oP  
//获得文件长度 u1;sH{YK>  
//分割文件 JpE7"Z"~MS  
//实例FileSplitterFetch hAU@}"=G  
//启动FileSplitterFetch线程 34<k)0sO  
//等待子线程返回 y/>IF|aX  
try{ \zLKSJ]  
if(bFirst) [PX%p;"D  
{ jT=fq'RK  
nFileLength = getFileSize(); CWY-}M  
if(nFileLength == -1) )0?u_Z]w9  
{ ,xI FF-[0  
System.err.println("File Length is not known!"); 9v@P|  
} Kw=][}d`D  
else if(nFileLength == -2) )}lO%B'K  
{ ^?5HagA  
System.err.println("File is not access!"); PvB{@82  
} +;/ s0  
else 8/T[dn  
{ hg2UZ% Y  
for(int i=0;i<nStartPos.length;i++) 10IX84  
{ = P$Q;d  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); W$xW9u8@+(  
} F4PWL|1  
for(int i=0;i<nEndPos.length-1;i++) QWwdtk  
{ )|wC 1J!L  
nEndPos = nStartPos[i+1]; $O_{cSKg7  
} ftxy]NLF  
nEndPos[nEndPos.length-1] = nFileLength; Qv6-,6<  
} P:%r3F  
} d.yATP  
T^
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# 11<=3Yj  
//启动子线程 t?wVh0gT  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; T~8kKw  
for(int i=0;i<nStartPos.length;i++) s"5wnp6pW  
{ @%BsQm  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 4^T_" W}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), P,@/ap7J  
nStartPos,nEndPos,i); "7J38Ej\  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ZRj/lQ2D  
fileSplitterFetch.start(); ^cCNQS}r  
} ?7uK:'8  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), *i>hFNLdOM  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); NA=m<n#  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 4*'ZabDD  
nEndPos = " + nFileLength); J,:Wv`N:9~  
// fileSplitterFetch[nPos.length-1].start(); 4s6,`-  
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//等待子线程结束 [<WoXS1LX  
//int count = 0;  [ J4n%  
//是否结束while循环 CsEU:v  
boolean breakWhile = false; jo' V.]\  
B#r"|x#[  
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while(!bStop) gg/2R?O]  
{ :.u2^*<  
write_nPos(); G=er0(7<  
Utility.sleep(500); Rj3ad3z'E  
breakWhile = true; KAgxIz!^-1  
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for(int i=0;i<nStartPos.length;i++) ?[;>1+D  
{ liMw(F2  
if(!fileSplitterFetch.bDownOver) N}nE?|N=5  
{ o)n=n!A  
breakWhile = false; 7{\6EC}d[&  
break; ~r_2V$sC2  
} TE:|w Xe  
} kB.CeG]
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if(breakWhile) k$GtzjN
 
break; 2~R%_r+<  
"B>8on8O  
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//count++; 3L36 2  
//if(count>4) aNBwb9X  
// siteStop(); B=~uJUr  
} =b, m31  
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System.err.println("文件下载结束！"); b=5ZfhIg[  
} ~n$\[rQ  
catch(Exception e){e.printStackTrace ();} .03Rp5+v  
} tUt_Q;%yC  
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//获得文件长度 my0
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public long getFileSize() 9N<=,!;5~s  
{ 4'TssRot@h  
int nFileLength = -1; ^B1$|C D,  
try{ >pp#>{}  
URL url = new URL(siteInfoBean.getSSiteURL()); NFF!g]QN  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Z/T(
4  
httpConnection.setRequestProperty("User-Agent","NetFox"); tSe[*V4{'  
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int responseCode=httpConnection.getResponseCode(); vR&b2G7o  
if(responseCode>=400) [=",R&uD$  
{ `Tei
 
processErrorCode(responseCode); p[&b@U#  
return -2; //-2 represent access is error oJQ \?~  
} z;MPp#Y  
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String sHeader; [RY Rt/?Q  
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for(int i=1;;i++) lF t^dl^  
{ ?C- ju8]|  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); m>
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//Utility.log(in.readLine()); `X)A$lLr  
sHeader=httpConnection.getHeaderFieldKey(i); [b_qC'K[  
if(sHeader!=null) 1 e]D=2y  
{ Z;,G:@
,  
if(sHeader.equals("Content-Length")) 0 vYG#S  
{ |>O
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); x4(8 =&Z  
break; ^C92R"*Qu  
} fzA Fn$[  
} x6^Y&,y9kU  
else bDm7$ (  
break; F`GXho[  
} %'X~9Pvi  
} r*dNta<  
catch(IOException e){e.printStackTrace ();} Ud7Z7?Ym  
catch(Exception e){e.printStackTrace ();} 1xu~@v60  
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Utility.log(nFileLength); 8]oolA:^4s  
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return nFileLength; CRD=7\0(D+  
} Ql%B=vgKL  
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//保存下载信息（文件指针位置） z~==7:Os  
private void write_nPos() D/JSIDd  
{ q#SEtyJL  
try{ 3=^)=yOd  
output = new DataOutputStream(new FileOutputStream(tmpFile)); s;..a&C'  
output.writeInt(nStartPos.length); I~^Xw7  
for(int i=0;i<nStartPos.length;i++) ,LlYRj 5  
{ ( mn:!3H%  
// output.writeLong(nPos); 00{a}@n  
output.writeLong(fileSplitterFetch.nStartPos); gwdAf%|f  
output.writeLong(fileSplitterFetch.nEndPos); Pouo# 5  
} 1)jeawVmj  
output.close(); N&eo;Ti  
} _RUL$Ds  
catch(IOException e){e.printStackTrace ();} ^*.+4iHx  
catch(Exception e){e.printStackTrace ();} ^G2M4+W|  
} SM%/pu;  
' Ttsscv  
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//读取保存的下载信息（文件指针位置） S;jD@j\t&  
private void read_nPos() tv
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{ l($8HAJ  
try{ tC(MaI  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); p2k`)=iX  
int nCount = input.readInt(); jvAjnh#  
nStartPos = new long[nCount]; ;]b4O4C\  
nEndPos = new long[nCount]; DA04llX~  
for(int i=0;i<nStartPos.length;i++) 5!cp^[rGL  
{
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nStartPos = input.readLong(); @}:E{J#g  
nEndPos = input.readLong(); x0jaTlU/  
} *W2)!C|  
input.close(); 4
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} ExSM=  
catch(IOException e){e.printStackTrace ();} F\^8k/0  
catch(Exception e){e.printStackTrace ();} SDV#p];u  
} LMx/0  
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3;VH'hh_  
private void processErrorCode(int nErrorCode) %p$XK(6  
{ vd(S&&]o1  
System.err.println("Error Code : " + nErrorCode); _p5#`-%mM  
} dP(.l}O  
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,  
//停止文件下载 C:}1r  
public void siteStop() T/2k2r4PD  
{ ]jC{o,?s  
bStop = true; h#KSKKNW  
for(int i=0;i<nStartPos.length;i++) eY
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fileSplitterFetch.splitterStop(); 1#%H!GKvTU  
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} p JT)X8K"  
} U,Uy0s2r  
//负责部分文件的抓取 od5nRb  
**FileSplitterFetch.java J(@" 7RX  
*/ 8Iu6r}k?~`  
package NetFox; =}kISh  
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import java.io.*; fM7B<eB  
import java.net.*; s
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/3Gq&[R{  
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public class FileSplitterFetch extends Thread { M2p|&Z%  
8<mloM-4  
YY:{/0?  
String sURL; //File URL 9#:fQ!3`  
long nStartPos; //File Snippet Start Position +_$s9`@]6  
long nEndPos; //File Snippet End Position xw_klHL-o  
int nThreadID; //Thread's ID R9 Ab.t  
boolean bDownOver = false; //Downing is over ]Idwy|eG  
boolean bStop = false; //Stop identical T4Vp0i  
FileAccessI fileAccessI = null; //File Access interface {U$XHG  
R]e&JoY  
A[^#8evaK  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException dor1(@no|  
{ |LZ{kD|  
this.sURL = sURL; G+Z ,ic  
this.nStartPos = nStart; ,Y
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this.nEndPos = nEnd; $[?N^   
nThreadID = id; /<n7iIK)  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 [?|yQ x  
} }2LWDQ;po  

%&&)[  
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public void run() !j`<iPI7B  
{ UkpTK8>&  
while(nStartPos < nEndPos && !bStop) " "m-5PGYo  
{ pZopdEFDK|  
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4'dN7E1*f  
try{  %G\nl  
URL url = new URL(sURL); 8y<.yfgG  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); <mlN\BcX;  
httpConnection.setRequestProperty("User-Agent","NetFox"); l
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String sProperty = "bytes="+nStartPos+"-"; !;h&@LXG(  
httpConnection.setRequestProperty("RANGE",sProperty); {l!{b1KJ  
Utility.log(sProperty); h)ZqZ'k$  
B }euIQB  
6xtgnl#T  
InputStream input = httpConnection.getInputStream(); uA[ :  
//logResponseHead(httpConnection); TP {\V>*Yz  
^.iRU'{  
RV_I&HD!  
byte[] b = new byte[1024]; 2(0%{*m  
int nRead; _b&26!gl  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 1uN;JN `_  
{ (}6\_k[}m  
nStartPos += fileAccessI.write(b,0,nRead); X,aRL6>r  
//if(nThreadID == 1) 6`Y:f[VB  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); }Vob)r{R@  
} HVoPJ!K3  
4)D~S4{E5  
"5<!   
Utility.log("Thread " + nThreadID + " is over!"); ><D2of|  
bDownOver = true; 035jU'  
//nPos = fileAccessI.write (b,0,nRead); keRLai7h  
} Y)F(-H)  
catch(Exception e){e.printStackTrace ();} 7F0J*M  
} ,'HjL:r  
} RHn3\N  
*(1<J2j  
-*KKrte  
//打印回应的头信息 LYL_Ah'=  
public void logResponseHead(HttpURLConnection con) XZ]ji9'  
{ !;(Wm6~*ad  
for(int i=1;;i++) h[iO'V
q  
{ kN1R8|pv  
String header=con.getHeaderFieldKey(i); "*D9.LyM  
if(header!=null) {+_p?8X  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 8g!79q\c4  
Utility.log(header+" : "+con.getHeaderField(header)); ~mt{j7  
else 48^C+#Jbc  
break; Vf~-v$YI  
} '}(>s%~  
} ;@ixrj0u  
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public void splitterStop() dR.?Kv(,E  
{ LKcp.i  
bStop = true; =,;$d&#*h  
} frPQi{u$  
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} .6$=]hdAp  
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/* %.f%Q?P  
**FileAccess.java |wv+g0]Pg^  
*//文件访问(定位，写) ,~38IIS>_  
package NetFox; +`gU{e,p  
import java.io.*; 0]*W0#{Zj  
$t^Td
<  
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public class FileAccessI implements Serializable{ 2e1%L,y{W  
YYFS ({  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 j0+D99{R  
RandomAccessFile oSavedFile; e#k rr  
long nPos; 1)h<
)  
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#tHYCSr]  
public FileAccessI() throws IOException &x\)] i2f  
{ 'D`lVUB  
this("",0); qGV(p}$O  
} B,_K mHItd  
E_A5KLP  
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public FileAccessI(String sName,long nPos) throws IOException KG(FA  
{ VT4>6u}  
oSavedFile = new RandomAccessFile(sName,"rw"); E"p _!!1  
this.nPos = nPos; H/M]YUs/3  
oSavedFile.seek(nPos); tlD^"eq4:  
} 5<`83;R9  
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public synchronized int write(byte[] b,int nStart,int nLen) n=JV*h0  
{ ,N,@9p  
int n = -1; 2
4 [cU  
try{ J`0dF<<{[y  
oSavedFile.write(b,nStart,nLen); ZDzG8E0Sq  
n = nLen; ]?T^tJ  
} Hpz1Iy@  
catch(IOException e) ZG1TRF "  
{ !9HWx_,|Z  
e.printStackTrace (); oXht$Q  
} ~Azj 
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9v;[T%%  
cy!P!t,@  
return n; &L?]w=*  
} eP:\\; ;  
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} V >eG\  
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/* <m~8pM  
**SiteInfoBean.java <5j%!6zo  
*/ }jC^&%|  
package NetFox; E A55!  
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public class SiteInfoBean { Bf  y  
=&k[qqxg  
9pj6`5Zn@6  
private String sSiteURL; //Site's URL u@:[ dbJ  
private String sFilePath; //Saved File's Path K@2"n| S;  
private String sFileName; //Saved File's Name Z-4/xi7  
private int nSplitter; //Count of Splited Downloading File Q6URaw#Yt`  
)i.pE]!+  
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public SiteInfoBean() A9]&w  
{//nSplitter的缺省值为5 \}n_Sk  
//default value of nSplitter is 5 4noy!h  
this("","","",5); .Ow8C  
} W+8s>  
r7V
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 2{BS `f  
{ )sK53O$  
sSiteURL= sURL; s{7bu|0  
sFilePath = sPath; ADOA&r[  
sFileName = sName; A2L"&dl  
this.nSplitter = nSpiltter; ?-2s}IJO  
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~&<vAgy,  
} Crj7n/mp]s  
]gnEo.R  
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public String getSSiteURL() +3XaAk  
{ ^yl}/OD  
return sSiteURL; /%jX=S.5h<  
} ;K>'Gl  
H{i|?
a)  
=~W=}  
public void setSSiteURL(String value) ci2Z_JA+  
{ tcl9:2/^]  
sSiteURL = value; SvkCx>6/G  
} nIL67&  
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public String getSFilePath() t~4Cf])  
{ 4bw4!z9G  
return sFilePath; nJYIkf
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} IaOR%Bg  
EBL-+%J8  
,UVu.RjXN  
public void setSFilePath(String value) K8[Um!(  
{ ='+I dn#5  
sFilePath = value; !"RRw&0M  
} [742s]j  
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w?8\9\ ;?  
public String getSFileName() A1Uy|Dl  
{ B1U!*yzG6  
return sFileName; GNrRc3dr$  
} l. cp[  
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H n]( )/  
public void setSFileName(String value) ?tqJkL#  
{ uF}B:53A  
sFileName = value; za 7+xF  
} @'M"c q  
+kE~OdZG  
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public int getNSplitter() -L6CEe  
{ [iO8R-N8d  
return nSplitter; eGpKoq7a  
} #+U1QOsz  
1$C?+H  
zv/dj04>  
public void setNSplitter(int nCount) d8 Jf3Mo  
{ (.Ak*  
nSplitter = nCount;  CDuA2e  
} *pnaj\  
} |`o1B;lc  
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t18j2P>`  
/* 3< 6h~ek)  
**Utility.java 6:; >id${  
*/ LCj3{>{/=  
package NetFox; /5L\:eX%  
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public class Utility { Qmo}esb'(  
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public Utility() j
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{ MXEI/mDYK  
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} 1HAnOy0   
=v<A&4  
//线程睡眠 0QfDgDX  
public static void sleep(int nSecond) C$C>RYE?.  
{ +%K~  
try{ vV9vB3K5?  
Thread.sleep(nSecond); EH M59s|B  
} 8qw{e`c  
catch(Exception e) &?1^/]'"r  
{ <~w3[i=  
e.printStackTrace (); 6P>}7R}  
} P*|=Z>%[0  
} , .;0xyc  
srO>l ;Vf/  
//日志 NR8`nc1~  
public static void log(String sMsg) m||9,z-  
{ %+|sbRBb  
System.err.println(sMsg); QE)zH)(  
} I''n1v?N  

,1Z([R*  
8c9<kGm$E  
public static void log(int sMsg) aL90:,V  
{ M,li\)J!&  
System.err.println(sMsg); &s?uMWR  
} 5}]+|d;  
} [ @"6:tTU  
.
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/* hp9LV2_5  
**TestMethod.java 7(tsmP  
*/ Nz`v+sp  
package NetFox; #<eD  
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qS!N\p~>  
public class TestMethod { Pz:,de~5Qm  
9Sd?,z  
{}Is&^3Z  
public TestMethod() aD'Ax\-  
{ ///xx/weblogic60b2_win.exe #rBfp|b]1  
try{ U2WHs3  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Tt{z_gU6  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); </xf4.C  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 9=T;Dxn  
fileFetch.start(); w4TQ4 Y  
} '2<r{  
catch(Exception e){e.printStackTrace ();} W  
2;:p H3  
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} u|AMqS  
Zxqlhq/)  
v;;3 K*c>  
public static void main(String[] args) p0zC(v0*  
{ LK
}FI*A_  
new TestMethod(); vo*oCfm  
} zSfUM.fM  
} `W~  
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