http断点续传简单实现（java)

/* 7; TS  
**SiteFileFetch.java @a%,0Wn  
*/ e Yyl=YW  
package NetFox; {EW}Wd  
import java.io.*; P/nXY  
import java.net.*; F:hJ^:BP  
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public class SiteFileFetch extends Thread { aFIet55o  
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SiteInfoBean siteInfoBean = null; //文件信息Bean [0/?(i|  
long[] nStartPos; //开始位置 3AWB Y.  
long[] nEndPos; //结束位置 vk{4:^6.TV  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 -6+HA9zz@C  
long nFileLength; //文件长度 OX8jCW  
boolean bFirst = true; //是否第一次取文件 xs.[]>nQN  
boolean bStop = false; //停止标志 y,Dfqt  
File tmpFile; //文件下载的临时信息 'v6Rd)E\z  
DataOutputStream output; //输出到文件的输出流 BOt\"N  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） H{yPi7 P  
public SiteFileFetch(SiteInfoBean bean) throws IOException -BEPpwb<g  
{ o<V-gS  
siteInfoBean = bean; _QXo4z!a8  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ,wRrx&  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); HK2`.'D  
if(tmpFile.exists ()) \+cQiN b@  
{ 8 ehC^Cg  
bFirst = false; r9b`3yr=  
read_nPos(); qIb(uF@l"  
} HnOF_Twq  
else Ty@&s58a  
{ _fMooI)U1  
nStartPos = new long[bean.getNSplitter()]; Ln`c DZSM  
nEndPos = new long[bean.getNSplitter()]; mcr71j  
} ?I7H ):  
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} 78 UT]<Q;K  
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public void run() J+.t\R  
{ L`Qiu@  
//获得文件长度 8nZPY)o  
//分割文件 +A:}5{  
//实例FileSplitterFetch rH-_L&
 
//启动FileSplitterFetch线程 aZBaIl6I  
//等待子线程返回 DOR
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try{ [q(7Jv  
if(bFirst) !).D  
{ Ay56@_d2  
nFileLength = getFileSize(); R0m}I5Frs  
if(nFileLength == -1) xNm<` Y?  
{ 0} {QQB  
System.err.println("File Length is not known!"); kB :")$  
} T1e}WJbFE  
else if(nFileLength == -2) IHB{US1G  
{ ^l iyWl  
System.err.println("File is not access!"); */Y@:Sjf  
} gbSZ- ej  
else Y
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{ xpSMbX{e  
for(int i=0;i<nStartPos.length;i++) 7v=Nh  
{
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); *[ A%tj%  
} fQe-v_K  
for(int i=0;i<nEndPos.length-1;i++) f+F /`P%  
{ A\ LTAp(I  
nEndPos = nStartPos[i+1]; "lUw{3  
} K_}vmB\2l  
nEndPos[nEndPos.length-1] = nFileLength; &&>OhH`  
} 5[;p<GqGN  
} b$M? _<G  
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//启动子线程 M%6{A+(  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; #n0P'@d,r  
for(int i=0;i<nStartPos.length;i++) *t*yozN  
{ kw1PIuz4&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), U?@UIhtM|  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), .|_+>){$w  
nStartPos,nEndPos,i); Z*kg= hs^  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); B"8^5#t4s  
fileSplitterFetch.start(); s>_ne0  
} O </<  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), S .1~#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", yyBfLPXZ  
nEndPos = " + nFileLength); ,qaIdw[  
// fileSplitterFetch[nPos.length-1].start(); dD!} P$
 
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//等待子线程结束 JYKaF6bx8  
//int count = 0; Y[*z6gP(  
//是否结束while循环 k>2 xm  
boolean breakWhile = false; |-2,k#|  
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while(!bStop) S%R:GZEf_  
{ b6'%nR*f  
write_nPos(); %o.{h  
Utility.sleep(500); wk<QYLEk  
breakWhile = true; xoA\^AA  
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for(int i=0;i<nStartPos.length;i++) 1b-4wonQd  
{ e(@YBQ/Z  
if(!fileSplitterFetch.bDownOver) j$4Tot  
{ W+Z] Y  
breakWhile = false; 1X.5cl?V  
break; @D[jUC$E  
} l[fU0;A  
} C6Ap  4  
if(breakWhile) r%}wPN(?D  
break; Klzsr,  
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//count++; !ANvXPp  
//if(count>4) Ia*eb%HG  
// siteStop(); C%85Aq*4  
} ~Yv"
=  
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System.err.println("文件下载结束！"); S^]i  
} Ratg!l|'-  
catch(Exception e){e.printStackTrace ();} 3+;]dqZ  
} m jC6(?V  
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//获得文件长度 $5z O=`  
public long getFileSize() '-p<E"#4Z  
{ 8p }E  
int nFileLength = -1; hs}nI/#  
try{ H,9e<x#own  
URL url = new URL(siteInfoBean.getSSiteURL()); ]xBQ7Xqf
|  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }rz}>((ZHF  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;]3Tuq  
~T7\lJ{%G  
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int responseCode=httpConnection.getResponseCode(); \/I@&$"F  
if(responseCode>=400) 2u4aCfIx  
{ )s4#)E
1  
processErrorCode(responseCode); 'oBT*aL  
return -2; //-2 represent access is error a]|P rjPI  
} !U>711$  
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String sHeader;
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for(int i=1;;i++) Zmw'.hL  
{ g|tnYN  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); hJ 4]GA'  
//Utility.log(in.readLine()); by,"Orpwq;  
sHeader=httpConnection.getHeaderFieldKey(i); .e%PK  
if(sHeader!=null) Z6\OkD  
{ ;  6
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if(sHeader.equals("Content-Length")) xG@zy4  
{ y((I2g1rv  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ,Ua`BWF  
break; H]K(`)y}4  
} v>CAA"LH  
} `j{5$X  
else L6c=uN  
break; gF+Uj( d  
} : &>PN,q>  
} `?{i dg  
catch(IOException e){e.printStackTrace ();} DyIuM{Owj  
catch(Exception e){e.printStackTrace ();} ?a+>%uWt  
}t#uSz^  
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Utility.log(nFileLength); |{udd~oE&  
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return nFileLength; A J<Sa=  
} 60(j[d-$p  
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//保存下载信息（文件指针位置） *o <S{  
private void write_nPos() w}nc^6qH  
{ b:VCr^vp  
try{ &6V[@gmD  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 'r3yFoP}  
output.writeInt(nStartPos.length); |Am +f.  
for(int i=0;i<nStartPos.length;i++) da<B6!  
{ ] }XsP  
// output.writeLong(nPos); 8i"v7}  
output.writeLong(fileSplitterFetch.nStartPos); tGv5pe*r  
output.writeLong(fileSplitterFetch.nEndPos); I(!i"b9  
} I~ Q2jg2  
output.close(); [vCZoG8+>  
} 1P i_V  
catch(IOException e){e.printStackTrace ();} M,nX@8 _h  
catch(Exception e){e.printStackTrace ();} %i[G6+-  
} }EM
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//读取保存的下载信息（文件指针位置） =UY)U-  
private void read_nPos() ypyqf55gK  
{ 5DB4vh  
try{ Itaq4^CE  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); !7)` g i  
int nCount = input.readInt(); %@Mv-A6)  
nStartPos = new long[nCount]; tgk] sQY  
nEndPos = new long[nCount]; oihn`DY{  
for(int i=0;i<nStartPos.length;i++) <!@*2/Q]J]  
{ G':wJ7[]`  
nStartPos = input.readLong(); t@=*k9  
nEndPos = input.readLong(); ,6N|?<26O  
} \M$
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input.close();  rvPY  
} 2;&K*>g&.  
catch(IOException e){e.printStackTrace ();} 3(?V!y{@  
catch(Exception e){e.printStackTrace ();} H{yUKZH*  
} $wnK"k%G  
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private void processErrorCode(int nErrorCode) NA@<v{z  
{ aL?+# j^"  
System.err.println("Error Code : " + nErrorCode);
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} 4th*=ku  
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//停止文件下载 !UPKy$  
public void siteStop() {Sl#z}@s  
{ MZ$x(Vcj  
bStop = true; w?;j5[j  
for(int i=0;i<nStartPos.length;i++) Z+8Q{|Ev  
fileSplitterFetch.splitterStop(); '.{tE*  
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} 5)@UpcjUA  
} FqWW[Bgd  
//负责部分文件的抓取 VWLqJd>tr1  
**FileSplitterFetch.java 6VUkZKc  
*/ ?:$aX@r  
package NetFox; Xh5&J9pw   
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import java.io.*; $c1zMkY)u  
import java.net.*; y"I8^CA  
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public class FileSplitterFetch extends Thread { z JBcz,  
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String sURL; //File URL \Bvy~UeE)>  
long nStartPos; //File Snippet Start Position 7QXp\<7  
long nEndPos; //File Snippet End Position f,(@K%  
int nThreadID; //Thread's ID .wpp)M.w;H  
boolean bDownOver = false; //Downing is over {SRv=g  
boolean bStop = false; //Stop identical -J& b~t@  
FileAccessI fileAccessI = null; //File Access interface S%6V(L|  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :OKU@l|  
{ p=T6Ix'_2e  
this.sURL = sURL; s$3WJ'yr  
this.nStartPos = nStart; G<m6Sf  
this.nEndPos = nEnd; }C'h<%[P  
nThreadID = id; 4qKMnYR  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 By;{Y[@rS  
} $5r1Si)  
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public void run() EmYu]"${1  
{ 4yDWVd;  
while(nStartPos < nEndPos && !bStop) D>6vI  
{ 1,Uf-i  
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try{ i}_d&.DbF  
URL url = new URL(sURL); 6xW17P  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); N 6t`45  
httpConnection.setRequestProperty("User-Agent","NetFox"); z#Cgd-^7.#  
String sProperty = "bytes="+nStartPos+"-"; 52v@zDY  
httpConnection.setRequestProperty("RANGE",sProperty); dz"HO!9  
Utility.log(sProperty); cS;O
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InputStream input = httpConnection.getInputStream(); Lv<)Dur0K  
//logResponseHead(httpConnection); ;yDXo\gm  
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byte[] b = new byte[1024]; tKLAA+Z  
int nRead; ibxtrt=  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 'qlWDt/  
{ IfF&QBi  
nStartPos += fileAccessI.write(b,0,nRead); Mw{skK>b  
//if(nThreadID == 1) D]zpG  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^SJa/I EZ.  
} :qxd s>Xm  
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Utility.log("Thread " + nThreadID + " is over!"); F^}n7h=qk  
bDownOver = true; zE
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//nPos = fileAccessI.write (b,0,nRead); TM$Ek^fQ.  
} !|;w(/  
catch(Exception e){e.printStackTrace ();} ko<VB#pOMr  
} *EzAo  
} J6*B=PX=(  
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//打印回应的头信息 WA79(B  
public void logResponseHead(HttpURLConnection con) xrky5[XoD  
{ Co^a$K  
for(int i=1;;i++) yi9c+w)b  
{ ]Zz<9zix  
String header=con.getHeaderFieldKey(i); p!w}hB598  
if(header!=null) -"Q[n,"Y  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); z0m[25FQG  
Utility.log(header+" : "+con.getHeaderField(header));
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else L~~Dj:%uq  
break; dk9nhS+faJ  
} q;a#?Du o  
} gZ1|b  
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public void splitterStop() `[J(au$z  
{ 4D\+_Ic3  
bStop = true; lt&30nf=  
} AFcA5:ja  
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} "yCe
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/* xR,;^R|C  
**FileAccess.java K{00 V#  
*//文件访问(定位，写) r6-'p0|   
package NetFox; |V|)cPQ  
import java.io.*; 8c'0"G@S  
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public class FileAccessI implements Serializable{ _u:4y4}  
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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 :6z0Ep"  
RandomAccessFile oSavedFile; m~Dq0 T  
long nPos; U.U.\   
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{*;]I?9Al  
public FileAccessI() throws IOException 
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{ ,6O9#1A&i  
this("",0); e6HlOGPVQH  
} i\;&CzC:  
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public FileAccessI(String sName,long nPos) throws IOException 4AOS}@~W  
{ Czr4 -#2  
oSavedFile = new RandomAccessFile(sName,"rw"); LGROEn<*d  
this.nPos = nPos; :ECK $Cu  
oSavedFile.seek(nPos); 0DB<hpC:5  
} s~Wu0%])Q  
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public synchronized int write(byte[] b,int nStart,int nLen) #A/J^Ko  
{ pq?[wp"  
int n = -1; NB5L{Gf6-  
try{ on;sq8;  
oSavedFile.write(b,nStart,nLen); U.Chf9a-  
n = nLen; 1mn$Rh&dO  
} #/t>}lc  
catch(IOException e) }gi1?a59  
{ @@/'b'  
e.printStackTrace (); y'!p>/%v  
} _RaVnMJKX4  
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return n; k]$E8[.t  
} !|<f%UO  
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} :*P___S=  
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/* [wy3Ld  
**SiteInfoBean.java  _WDBG  
*/ i. u15$  
package NetFox; )|Vg

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public class SiteInfoBean { X[~f:E[1J  
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private String sSiteURL; //Site's URL C*{15!d:G  
private String sFilePath; //Saved File's Path t)oES>W1  
private String sFileName; //Saved File's Name g~Nij~/  
private int nSplitter; //Count of Splited Downloading File XU;{28P  
\}u7T[R=`  
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public SiteInfoBean() \2gvp6  
{//nSplitter的缺省值为5 K{=r.W  
//default value of nSplitter is 5 o]|oAN9  
this("","","",5); %|`:5s-T%  
} C NzSBm  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) p-T~x$"c|  
{ de=5=>P7  
sSiteURL= sURL; xS H6n  
sFilePath = sPath; $vgmoJ@X0  
sFileName = sName; vGPf`2/j.  
this.nSplitter = nSpiltter; Ypn%[sSOp  
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} qXP1Q3  
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public String getSSiteURL() VeNNsg>&  
{ jlRl2 #"  
return sSiteURL; %2@ Tj}xa  
} {*M>X}voS  
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public void setSSiteURL(String value) Ad}-I%Ie  
{ ~J:$gu~`  
sSiteURL = value; :c~9>GCE&  
} :Bx+WW&P.i  

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public String getSFilePath() ";-{~  
{ xE G+%Uk{  
return sFilePath; v5&xY2RI7  
} vF.?] u  
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public void setSFilePath(String value) dJdD"xj  
{ dxzv
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sFilePath = value; i63`B+L{  
} 8~&F/C*  
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4)z3X\u|Z2  
public String getSFileName() Qag|nLoT  
{ ^G|w8t+^  
return sFileName; @K,2mhE~h  
} BpQ;w,sefq  
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public void setSFileName(String value) DH
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{ th.M.jas  
sFileName = value; 2k.S[?)  
} rtB|N-  
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public int getNSplitter() 5S&aI{;9<  
{ ~hS .\h  
return nSplitter; Tjd&^m  
} E0sbU<11  
#@nZ4=/z  
7^kH8qJ)  
public void setNSplitter(int nCount) z7'n, [  
{ JiKImz  
nSplitter = nCount; |x1
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} 2"T8^r|U  
} N70zjy4?fL  
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m
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/* 72u db^  
**Utility.java j6HR&vIM  
*/ /-><k,mL?  
package NetFox; ~oo'ky*H!  
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public class Utility { fkG##!  
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public Utility() gY%&IHQ'  
{ w%rg\E  
"Y(^F bs  
Gh=<0WaF=  
} "\}21B~{7'  
^971<B(v  
//线程睡眠 f x%z|K  
public static void sleep(int nSecond) 7~%  
{ I;kUG_c(4  
try{ >M8^Jgh  
Thread.sleep(nSecond); ]8cX#N,M  
} x.RZ!V-  
catch(Exception e) ]CYe=m1<2Q  
{ yfrgYA  
e.printStackTrace (); )M~5F,)  
} @E}4LTB  
} p4/
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//日志 ~ >6(@~6  
public static void log(String sMsg) |{$Vk%cUE  
{ m$U2|5un&  
System.err.println(sMsg); B${Q Y)t  
} y90wLU9f  
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public static void log(int sMsg) n,D&pl9f  
{ WIKSz {"=/  
System.err.println(sMsg); ?mw
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} /L{V3}[j  
} 7w\L<v
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/* cS#
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**TestMethod.java o4U0kiI@  
*/ A3^_'K  
package NetFox; \r1nMw3&  
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public class TestMethod { .fAHP 5-  
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public TestMethod() U3u j`Oq  
{ ///xx/weblogic60b2_win.exe uA4xxY  
try{ S-5O$EnD  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); H S
)$|m_  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ~^bf1W[  
SiteFileFetch fileFetch = new SiteFileFetch(bean); (<2!^v0.M  
fileFetch.start(); I;Pd}A_}=_  
} *b7evU *1  
catch(Exception e){e.printStackTrace ();} ^P|Zze zwU  
)=nB32~J"  
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} BdB9M8fM  
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+#
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public static void main(String[] args) <ivq}(%72  
{ O{x-9p  
new TestMethod(); _MWW  
} 3/y"kl:<-  
} Ax6zx  
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