http断点续传简单实现（java)

/* R`NYEptJ  
**SiteFileFetch.java LBw1g<&  
*/ I ce~oz)  
package NetFox; Z9v31)q(  
import java.io.*; d[iQ`YW5  
import java.net.*; wON!MhA;  
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public class SiteFileFetch extends Thread { ROH|PKb7  
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SiteInfoBean siteInfoBean = null; //文件信息Bean zYH&i6nj  
long[] nStartPos; //开始位置 /:cd\A}  
long[] nEndPos; //结束位置 OAgniLv  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 u+9hL4  
long nFileLength; //文件长度 0CHH)Bku  
boolean bFirst = true; //是否第一次取文件 O%\*@4zM  
boolean bStop = false; //停止标志 jk;j2YNPw  
File tmpFile; //文件下载的临时信息 /p/]t,-j2  
DataOutputStream output; //输出到文件的输出流 mVj9,q0  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） (Lbbc+1m  
public SiteFileFetch(SiteInfoBean bean) throws IOException j`EXlc~  
{ z}.e]|b^H  
siteInfoBean = bean; l|u>Tb|V  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); FnwJ+GTu  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); -M\<nx  
if(tmpFile.exists ()) {B~QQMEow  
{ 4VHn \  
bFirst = false; kXViWOXU^  
read_nPos(); 0Fq} N  
} G?yLo 'Ulo  
else @="Pn5<]C  
{ |44Ploz2b  
nStartPos = new long[bean.getNSplitter()]; aEB_#1  
nEndPos = new long[bean.getNSplitter()]; ~$c\JKH-  
} \P[Y`LYL  
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} ldf\;Qk  
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public void run() b1cy$I  
{ z'Hw  
//获得文件长度 $z6_@`[  
//分割文件 `>o{P/HN  
//实例FileSplitterFetch t5Sy V:fP  
//启动FileSplitterFetch线程 *VCXihgo  
//等待子线程返回 Z{*\S0^ST  
try{ |]bsCmD  
if(bFirst) Lj({[H7D!  
{ g>%o #P7  
nFileLength = getFileSize(); soxc0OlN  
if(nFileLength == -1) L;z?aZ7n  
{ %UrueMEO  
System.err.println("File Length is not known!");  m!!/Za  
} <sbu;dQ`  
else if(nFileLength == -2) h4gXvPS&r  
{ \doUTr R  
System.err.println("File is not access!"); M/f<A$xx_  
} H*n-_{h"t  
else !)f\%lb  
{ zpn9,,~u  
for(int i=0;i<nStartPos.length;i++) yZY\MB/  
{ gjyYCjF  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); e+7"/icK  
} K-)] 1BG  
for(int i=0;i<nEndPos.length-1;i++) J3V= 46Yc  
{ ;?Tbnn Wn  
nEndPos = nStartPos[i+1]; P8:dU(nlW  
} 5Pc;5 o0C  
nEndPos[nEndPos.length-1] = nFileLength; Z?q]bSIT  
} 51.%;aY~z  
} %SUQ9\SEs  
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//启动子线程 ]K%!@O!  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]JR +ayk7  
for(int i=0;i<nStartPos.length;i++) 'we>q@  
{ >C~6\L`c  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), bQ5\ ]5M  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), B|X!>Q<g  
nStartPos,nEndPos,i); LXCx~;{\  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); {7pli{`  
fileSplitterFetch.start(); {Hk}Kow  
} <\S:'g"(  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), W!(LF7_!  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); >KKMcTOYY  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", tZB<on<.)  
nEndPos = " + nFileLength); (uidNq
 
// fileSplitterFetch[nPos.length-1].start(); hFBe,'3M  
]
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//等待子线程结束 Dum9l
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//int count = 0; k==h|\|  
//是否结束while循环 AwF:Iu^3n  
boolean breakWhile = false; |vzl. ^"-  
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while(!bStop) l9H!au=  
{ 7cMv/g^h@  
write_nPos(); uXl3k:_n  
Utility.sleep(500); An/|+r\  
breakWhile = true; >c}u>]D  
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for(int i=0;i<nStartPos.length;i++) =H]@n|$(  
{ 2I{"XB  
if(!fileSplitterFetch.bDownOver) pI<f) r  
{ l}M!8:UzU  
breakWhile = false; o[D9I hs  
break; Srd4))2/0  
} is@?VklnB  
} 5Jnlz@P9  
if(breakWhile) E&:,oG2M  
break; I1&aM}y{G  
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//count++; #A8sLkY  
//if(count>4) *}W_+qo"  
// siteStop(); 8*a&Jl  
} `~q<N  
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System.err.println("文件下载结束！"); uFga~&#g  
} #gw]'&{8D  
catch(Exception e){e.printStackTrace ();} /; 85i6  
} IV)
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//获得文件长度 +X]vl=0  
public long getFileSize() 7"D.L-H  
{ )@bQu~Y  
int nFileLength = -1; 3"\lu?-E  
try{ Pj%|\kbNs  
URL url = new URL(siteInfoBean.getSSiteURL()); VJll  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 
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httpConnection.setRequestProperty("User-Agent","NetFox"); Pg7Yp2)Oli  
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int responseCode=httpConnection.getResponseCode(); E8&TO~"a]e  
if(responseCode>=400) Ozf@6\/t  
{ >b4eL59  
processErrorCode(responseCode); !jR=pIfq  
return -2; //-2 represent access is error b>JDH1)  
} SByW[JE  
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String sHeader; BIL Lq8)  
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for(int i=1;;i++) 3sZ\0P}   
{ ,s;UfF  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 5l*&>C[(i  
//Utility.log(in.readLine()); G,w(d@  
sHeader=httpConnection.getHeaderFieldKey(i); Thit  
if(sHeader!=null) VY\&8n}e(  
{ SasJic2M  
if(sHeader.equals("Content-Length")) R{T$[$6S  
{ bA->{OPkT  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 3? +H
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break; {Y9q[D'g.  
} '2^Q1{ :\  
} 6)Lk-D  
else tIgN$BHR>  
break; i~J'%a<Qp  
} wj0\$NQ=x  
} 6!FQzFCZq  
catch(IOException e){e.printStackTrace ();} VP]%Hni]  
catch(Exception e){e.printStackTrace ();} B^9j@3Ux  
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Utility.log(nFileLength); y'*K|aTG  
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return nFileLength; U/NoP4~{  
} ~qOa\#x_  
}vM(
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//保存下载信息（文件指针位置） V~5jfcd  
private void write_nPos() OI*Xt`  
{ 4r}8lpF_(  
try{ D,FkB"ZZE  
output = new DataOutputStream(new FileOutputStream(tmpFile)); BThrO d  
output.writeInt(nStartPos.length); ?5 7Sk+  
for(int i=0;i<nStartPos.length;i++) %bfQ$a:  
{ <UQbt N-B\  
// output.writeLong(nPos); '."ed%=MC  
output.writeLong(fileSplitterFetch.nStartPos); 
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output.writeLong(fileSplitterFetch.nEndPos); HA>OkA/  
} n7-6- #  
output.close(); <e</m)j  
} y h9*z3  
catch(IOException e){e.printStackTrace ();} 9qG6Pb  
catch(Exception e){e.printStackTrace ();} BF{Y"8u$  
} b1?'gn~  
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//读取保存的下载信息（文件指针位置） )hfpwdQ  
private void read_nPos() oM
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{ <W$mj04@  
try{ Z?m3~L9L2  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); `+Q%oj#FF  
int nCount = input.readInt(); ]GQG~H^  
nStartPos = new long[nCount]; Q$@I"V&G.  
nEndPos = new long[nCount]; 9zy!Fq  
for(int i=0;i<nStartPos.length;i++) ZExlGC  
{ TbW38\>.R  
nStartPos = input.readLong(); jtc]>]6i  
nEndPos = input.readLong(); NHZz _a=  
} 9mTJ|sN:e  
input.close(); hZ  
} '(|ofJe!  
catch(IOException e){e.printStackTrace ();} _zi|  
catch(Exception e){e.printStackTrace ();} WEi2=3dV  
} @2 fg~2M1  
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private void processErrorCode(int nErrorCode) | h#u^v3  
{ W|63Ir67  
System.err.println("Error Code : " + nErrorCode); 7E~;xn;  
} fS78>*K  
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W v+?
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//停止文件下载 A{D];pE`  
public void siteStop() Fy-t T]Q9  
{ HRfYl,S,  
bStop = true; wEvVL  
for(int i=0;i<nStartPos.length;i++) P me^l%M  
fileSplitterFetch.splitterStop(); |4 0`B% Z  
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} O[JL+g4  
} ZX./P0  
//负责部分文件的抓取 `&ckZiq  
**FileSplitterFetch.java .5ha}=
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*/ .jWC$SVR  
package NetFox; zue~ce73J  
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import java.io.*; VQ9/Gxdeo  
import java.net.*; n[Y~]  
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public class FileSplitterFetch extends Thread { H%Q7D-  
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l?n\i]
'  
String sURL; //File URL JO6)-U$7UG  
long nStartPos; //File Snippet Start Position |imM#wF  
long nEndPos; //File Snippet End Position }*pi<s  
int nThreadID; //Thread's ID ?QdWrE_  
boolean bDownOver = false; //Downing is over PP33i@G  
boolean bStop = false; //Stop identical @YTaSz$L  
FileAccessI fileAccessI = null; //File Access interface 9 X`Sm}i  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException )W _v:?A9  
{ 68C%B9.b'  
this.sURL = sURL; |"CZ
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this.nStartPos = nStart; 5(Q%XQV*P  
this.nEndPos = nEnd; y,,dCca  
nThreadID = id; -ifFbT+x  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 4yA+h2  
} 0rs"o-s<  
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public void run() ^KT Y?  
{ scz&h#0V  
while(nStartPos < nEndPos && !bStop) [MM~H0=s  
{ !Pfr,a  
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try{ uGK.\PB$  
URL url = new URL(sURL); a![{M<Y~  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); IDriGZZ<)6  
httpConnection.setRequestProperty("User-Agent","NetFox"); ytJ/g/,A0i  
String sProperty = "bytes="+nStartPos+"-"; xHLlMn4M  
httpConnection.setRequestProperty("RANGE",sProperty); r1{@Ucw2  
Utility.log(sProperty); ">,|V-H  
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InputStream input = httpConnection.getInputStream(); g(7rTyp4)  
//logResponseHead(httpConnection); ?ri?GmI|  
9Uekvs=r=M  
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byte[] b = new byte[1024]; bUdLs.:  
int nRead; Q1I6$8:7  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) x}I+Iggi  
{ J$w<$5UY  
nStartPos += fileAccessI.write(b,0,nRead); C]`$AqKl  
//if(nThreadID == 1) qvKG-|j  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); z3m85F%dR  
} WUXx;9>  
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Utility.log("Thread " + nThreadID + " is over!"); 6@F9G4<Z  
bDownOver = true; sW'AjI  
//nPos = fileAccessI.write (b,0,nRead); dhf!o0'1M  
} u5b|#&-mX  
catch(Exception e){e.printStackTrace ();} Y>dzR)~3[  
} W ]?G}Q;  
} X Dm[Gc>(~  
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m6\E$;`  
//打印回应的头信息 +RMSA^  
public void logResponseHead(HttpURLConnection con) i
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{ }t=!(GOb}  
for(int i=1;;i++) }9#r0Vja  
{ pis`$_kmwV  
String header=con.getHeaderFieldKey(i); P90yI  
if(header!=null) BWv^zi  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 7p16Hv7y~  
Utility.log(header+" : "+con.getHeaderField(header)); IT7
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else J~zUp(>K  
break; o!Ieb  
} ;yLu R  
} l<LP&  
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public void splitterStop() Y^;ovH~ ve  
{ m_
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bStop = true; D4lG[qb  
} 0oZ= yh  
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} < #}5IQ5`Z  
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/* Ms5ap<q#  
**FileAccess.java HIR~"It$  
*//文件访问(定位，写) bz2ztH9 n  
package NetFox; WwBOM~/`2  
import java.io.*; ;
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public class FileAccessI implements Serializable{ HJLG=mU  
G )trG9 .a  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 m '|bGV  
RandomAccessFile oSavedFile; sV{,S>s  
long nPos; k}kQI~S9  
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public FileAccessI() throws IOException ?GoR^p #p  
{ l|~A#kq  
this("",0); vMi;+6'n>  
} Jr ,;>   
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public FileAccessI(String sName,long nPos) throws IOException Vod\a5c  
{ dGYn4i2k?  
oSavedFile = new RandomAccessFile(sName,"rw"); Ustv{:7v  
this.nPos = nPos; 4$iz4U:P  
oSavedFile.seek(nPos); q77;ZPfs8  
} /ivJsPH  
&Fzb6/  
B:;pvW]  
public synchronized int write(byte[] b,int nStart,int nLen) 8>2.UrC  
{ j9x<Y]  
int n = -1; fcRxp{*zO  
try{ 'RQ+g}|Ba!  
oSavedFile.write(b,nStart,nLen); [LjT*bi  
n = nLen; L%*!`T
N  
} hYT0l$Ng  
catch(IOException e) szZr4y<8|1  
{
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e.printStackTrace (); SIF/-{i(X  
} [fya)}  
@Q ]
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7 S#J>*  
return n; L3u&/Tn2  
} LEbB(x;@  
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} xjuN
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/* uB]7G0g:  
**SiteInfoBean.java $<dH?%!7  
*/ $Uq|w[LA  
package NetFox; :t"^6xt  
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public class SiteInfoBean { F 5bj=mI  
n71r_S*  
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private String sSiteURL; //Site's URL ?K$(817  
private String sFilePath; //Saved File's Path M)J5;^["  
private String sFileName; //Saved File's Name NR5gj-B[  
private int nSplitter; //Count of Splited Downloading File =1FRFZI!j  
o lR?n(v  
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public SiteInfoBean() :}L[sl\R  
{//nSplitter的缺省值为5 U8s2|G;K  
//default value of nSplitter is 5 !=*g@mgF  
this("","","",5); T]f ;km  
} ExY]Sdx  
MnsJEvn/  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) E<{R.r  
{ <.x{|p  
sSiteURL= sURL; Thp[+KP>  
sFilePath = sPath; p,5i)nEFj  
sFileName = sName; Go`vfm"S  
this.nSplitter = nSpiltter; e8>})  
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} -/wtI   
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public String getSSiteURL() YFLZ%(  
{ s[RAHU  
return sSiteURL; :T^a&)aL%  
} 4M=]wR;  
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public void setSSiteURL(String value) <prk8jSWV  
{ OZb-:!m*  
sSiteURL = value; a5dLQxb  
} -P(efYk  
jnkR}wAA  
!hA-_  
public String getSFilePath() 6+#Ydii9E  
{ =m]v8`g  
return sFilePath; 2prU  
} -V*R\,>  
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public void setSFilePath(String value) A]_7}<<N  
{ oM
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sFilePath = value; lF<]8m%F  
} N~nziY*C,*  
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public String getSFileName() aj-Km`5r}  
{ k%]3vRo<  
return sFileName; YU'k#\gi*  
} aG-vtld  
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public void setSFileName(String value) #>a\>iKQ2q  
{ %e8@*~h@  
sFileName = value; ]vB$~3||  
} pE3?"YO  
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^)470K`%)  
public int getNSplitter() /`Ug9,*  
{ WqR&&gz  
return nSplitter; PF0_8,@U  
} 'NbHa!  
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public void setNSplitter(int nCount) :;v~%e{k  
{ [@_Jj3`4  
nSplitter = nCount; cRC6 s8  
} .y'>[  
} 3xy<tqfr  
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DcS+_>a\{l  
/* {Ea b j  
**Utility.java xf'V{9*  
*/ 5p,RI&nlN  
package NetFox; W Tcw4  
;_XFo&@  
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public class Utility { FBG4pb9=~  
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public Utility() 3RUy,s  
{  >^O7  
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} 2/U.|*mH  
qRu~$K  
//线程睡眠 b;L\EB  
public static void sleep(int nSecond) Q@=Q0  
{ zWnX*2>b  
try{ xPdG*OcX!  
Thread.sleep(nSecond); \wmN  
} 0RzEY!9g+  
catch(Exception e) XjBW9a  
{ ,S\CC{!  
e.printStackTrace (); S0$8@"~=  
} 9FF0%*tGo  
} s$IDLs,WM  
B 5L2<  
//日志 "mo?* a$Sk  
public static void log(String sMsg) eB2a
-,  
{ %q"%AauJR  
System.err.println(sMsg); D2#ZpFp"h  
} V(}:=eK  
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k``_EiV4t  
public static void log(int sMsg) yER(6V'\iQ  
{ >k|5Okq g  
System.err.println(sMsg); HH`'*$]7  
} -+-?w|}qV  
} YH$-g  
53_Hl]#qZ  
pR
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/* SV4E0c>  
**TestMethod.java p;a,#IJu  
*/ v{RZJ^1  
package NetFox; #{0HYg?(f  
W@>% {eE  
&{5,:%PXw  
public class TestMethod { VCYwzB  
,};&tR  
#-rH1h3*q  
public TestMethod() 0^ _uV9r  
{ ///xx/weblogic60b2_win.exe XoK:N$\}t  
try{ !6 #X>S14  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); _=>He=v/  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); . P viA  
SiteFileFetch fileFetch = new SiteFileFetch(bean); I]|Pq  
fileFetch.start(); oE@a'*.\  
} 3l]lwV  
catch(Exception e){e.printStackTrace ();} Mzw X>3x  
9v!1V,`j"  
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} VgC2+APg  
+V^;.P</  
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public static void main(String[] args) [bNx^VP*  
{ bB;5s`-  
new TestMethod(); r!a3\ep  
} 9Ly]DZ;L  
} qH6>!=00  
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