http断点续传简单实现（java)

/* P;X0L{u0H  
**SiteFileFetch.java ulEtZ#O{_  
*/ J!Rq
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package NetFox;  LR4W  
import java.io.*; f*m^x7  
import java.net.*; I;<__  
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public class SiteFileFetch extends Thread { $fPiR  
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SiteInfoBean siteInfoBean = null; //文件信息Bean !QqVJ a{j  
long[] nStartPos; //开始位置 Pc+,iK>
 
long[] nEndPos; //结束位置 zQGj,EAM}  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 e-xT.RnQ  
long nFileLength; //文件长度 AXo)(\  
boolean bFirst = true; //是否第一次取文件 @P=n{-pIW  
boolean bStop = false; //停止标志 ]r#NjP  
File tmpFile; //文件下载的临时信息 96gaun J  
DataOutputStream output; //输出到文件的输出流 >Fe=PRs  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） mEb`ET|  
public SiteFileFetch(SiteInfoBean bean) throws IOException i!<(R$Lo  
{ 11!4#z6w  
siteInfoBean = bean; M%!j\}2A  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); mkgL/h*  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); K|;L{[[yH  
if(tmpFile.exists ()) xi.QHKBZaH  
{ %u Dd#+{  
bFirst = false; 0'zjPE#  
read_nPos(); ~PN[ #e]  
} idS+&:'  
else I'<sJs*p  
{ 5mZ9rLn  
nStartPos = new long[bean.getNSplitter()]; {-|El}.M  
nEndPos = new long[bean.getNSplitter()]; _JKz5hSl  
}  =wl0  
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} 7i=ER*F~  
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public void run() !_&;#j](  
{ Xi=4S[.4  
//获得文件长度 ?.MlP,/K  
//分割文件 (tg+C\ S.  
//实例FileSplitterFetch @3I?T Q1  
//启动FileSplitterFetch线程 4LJOT_  
//等待子线程返回 a=[|"J<M  
try{ +:J:S"G  
if(bFirst) S! .N3ezn  
{ L_=3`xE _  
nFileLength = getFileSize(); ^<aj~0v  
if(nFileLength == -1) v1
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{ BK.RY
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System.err.println("File Length is not known!"); (<|1/^~=  
} q}&+{dN\1  
else if(nFileLength == -2) You~ 6d6Om  
{ $K1
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System.err.println("File is not access!"); L$ju~0jl)%  
} (g tOYEqx  
else MR* %lZpB  
{ Sh<A936/E  
for(int i=0;i<nStartPos.length;i++) (B].ppBii  
{ H_%ae'W  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); <9Ytv|t@0  
} JNA_*3'  
for(int i=0;i<nEndPos.length-1;i++) ;|CG9|p
 
{ ^687U,+  
nEndPos = nStartPos[i+1]; T zHR  
} oIKuo~  
nEndPos[nEndPos.length-1] = nFileLength;  8KzH -  
} _<)HFg6  
} ^;EwZwH[  
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//启动子线程 ZZ].h2=K  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; d5=yAn-+=  
for(int i=0;i<nStartPos.length;i++) 6 c-9[-Px  
{ 3cFvS[JG  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), :XO7#P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), >LFj@YW_)  
nStartPos,nEndPos,i); MV?sr[V-oP  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); T%2%*oa  
fileSplitterFetch.start(); VmTgD96  
} e/IVZmUn^  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2-wgbC5  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 6c[ L*1  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Nb
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nEndPos = " + nFileLength); bB.Yq3KI  
// fileSplitterFetch[nPos.length-1].start(); DJH,#re>  
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//等待子线程结束 jTok1k  
//int count = 0; \Xg`@JrTM  
//是否结束while循环 ;;zd/n2b  
boolean breakWhile = false; N*Xl0m(Q  
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9/5EyV  
while(!bStop) tkhEjTZ  
{ TfA;4^  
write_nPos(); &_Gu'A({J  
Utility.sleep(500);  #U/L8  
breakWhile = true; |Lz7}g=6  
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for(int i=0;i<nStartPos.length;i++)
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{ $K!6T  
if(!fileSplitterFetch.bDownOver) rK cr1VFy  
{ zm^5WH  
breakWhile = false; z%/<|` 7  
break; z-h7v5i"  
} yc@:*Z  
} bKPjxN?!9  
if(breakWhile) ?*U:=|
  
break; rj;~SC{  
boIFN;Aq"  
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//count++; ch0x*[N@  
//if(count>4) ~ZRtNL9  
// siteStop(); T;B/Wm!x  
} x@<!#d+  
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System.err.println("文件下载结束！"); `qr.@0whP  
} lJBZ0  
catch(Exception e){e.printStackTrace ();} :j% B(@b  
} kX'a*AG  
KU;m.{  
unkA%x{W;  
//获得文件长度 ~RnBs`&!  
public long getFileSize() qnU$Pd  
{ lKy4Nry9  
int nFileLength = -1; m\J"P'=  
try{ 7e@Bkq0)  
URL url = new URL(siteInfoBean.getSSiteURL()); Zq\ p%AU9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); LwEc*79  
httpConnection.setRequestProperty("User-Agent","NetFox"); T04&Tl'CT  
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int responseCode=httpConnection.getResponseCode(); (:J U  
if(responseCode>=400) <p8>"~R  
{ (I(k$g[>  
processErrorCode(responseCode); F#\+.inO  
return -2; //-2 represent access is error  B*Q  
} \!'K#%]9  
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String sHeader; q|R$A8)L.  
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for(int i=1;;i++) #'h(o/hz&&  
{ %v1*D^))  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); [wjH;f>SQ  
//Utility.log(in.readLine()); *", BP]]  
sHeader=httpConnection.getHeaderFieldKey(i); >U')ICD~  
if(sHeader!=null) H6-{(: *<  
{ F5f1j]c  
if(sHeader.equals("Content-Length")) AV["%$:  
{ ^]?Yd)v  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); kZvh<NFh_  
break; J~rjI24  
} \b|Q`)TK  
} |0aGX]Y  
else 9 kS;_(DB  
break; <<9Y=%C+  
} W|[k]A` 2  
} G X>T~i\f8  
catch(IOException e){e.printStackTrace ();} 3`Q>s;DjIU  
catch(Exception e){e.printStackTrace ();} u=p-]?  
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e!*%U=[Q  
Utility.log(nFileLength); D z5(v1I9A  
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return nFileLength; p4{3H+y  
} .FAuM~_99b  
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>d#6qXKAU  
//保存下载信息（文件指针位置） } T<oLvS  
private void write_nPos() pNR69/wGi  
{ de?lO;8  
try{ <\S j5  
output = new DataOutputStream(new FileOutputStream(tmpFile)); DM@&=c  
output.writeInt(nStartPos.length); $ *^E  
for(int i=0;i<nStartPos.length;i++) 'l3K*lck  
{ x<e-%HB*-  
// output.writeLong(nPos); .TWX,#  
output.writeLong(fileSplitterFetch.nStartPos); _79 ?,U]  
output.writeLong(fileSplitterFetch.nEndPos); Y=N; Bj  
} <E&"]  
output.close(); ) _O
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} T@H2[ 7[;  
catch(IOException e){e.printStackTrace ();} LC:bHM,e  
catch(Exception e){e.printStackTrace ();} M4TFWOC1  
} W&(98}oT  
`` mi9E  
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//读取保存的下载信息（文件指针位置） lw"5p)aB  
private void read_nPos() A4uDuB;;ZQ  
{ l<mEGKB#  
try{ k@= LR  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); P(BV J_n  
int nCount = input.readInt(); r=ds'n"  
nStartPos = new long[nCount]; w~(x*R}  
nEndPos = new long[nCount]; L]HYk}oD.  
for(int i=0;i<nStartPos.length;i++) tqo!WuZAj  
{ kaj6C_k|  
nStartPos = input.readLong(); ';bovh@*  
nEndPos = input.readLong(); ZM%z"hO9R  
} ]tVXao  
input.close(); RDu'N  
} m}3POl/*j  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();} R9z^=QKcH  
} \3@AC7  
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private void processErrorCode(int nErrorCode) q#~]Hp=W5  
{ |.Pl[y  
System.err.println("Error Code : " + nErrorCode); 'qg q8  
} +tXOP|X  
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//停止文件下载 #dgWXO  
public void siteStop() D%Y{(l+X  
{ j\SW~}d9  
bStop = true; cAE.I$T(  
for(int i=0;i<nStartPos.length;i++) yxa~Rz/  
fileSplitterFetch.splitterStop(); 3yAzt*dZ  
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} ?=uw0~O[  
} z!I(B^)BkT  
//负责部分文件的抓取 5Y8/ZW~D0  
**FileSplitterFetch.java :K6(`J3Y"^  
*/ o= %Fh
 
package NetFox; 9GZKT{*  
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import java.io.*; NX(.Lw}  
import java.net.*; '?~k`zK  
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public class FileSplitterFetch extends Thread { t*)-p:29h  
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String sURL; //File URL q#RVi8('  
long nStartPos; //File Snippet Start Position WqC6c&NM  
long nEndPos; //File Snippet End Position TvWhy`RQ  
int nThreadID; //Thread's ID E5M*Gs  
boolean bDownOver = false; //Downing is over ),-4\!7  
boolean bStop = false; //Stop identical iM Xl}3
 
FileAccessI fileAccessI = null; //File Access interface nV0"q|0K;  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException uj-q@IKe  
{ -hP@L ++D  
this.sURL = sURL; [D H@>:"dd  
this.nStartPos = nStart; {O,Cc$_  
this.nEndPos = nEnd; ]AGJPuX  
nThreadID = id; d*lnXzQor  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 <oSk!6*  
} .Wq`qF(;  
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public void run() .O'gD.|^N  
{ <)]B$~(a  
while(nStartPos < nEndPos && !bStop) m//(1hWv7  
{ VB 8t"5  
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try{ 5CkM0G`  
URL url = new URL(sURL); J|Lk::Ri  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); x c-=;|s  
httpConnection.setRequestProperty("User-Agent","NetFox"); 56o?=|  
String sProperty = "bytes="+nStartPos+"-"; dxkXt  k  
httpConnection.setRequestProperty("RANGE",sProperty); @Ey(0BxNu  
Utility.log(sProperty); MWCP/~>a2  
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InputStream input = httpConnection.getInputStream(); 0rT-8iJp4P  
//logResponseHead(httpConnection); flLC\  
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byte[] b = new byte[1024]; ~S R:,R  
int nRead; XQk9 U  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0X)'8N  
{ %+G/oF|  
nStartPos += fileAccessI.write(b,0,nRead); hSD)|  
//if(nThreadID == 1)  { Lt\4h  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); f
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} r&\}E+  
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Utility.log("Thread " + nThreadID + " is over!"); =? xA*_^  
bDownOver = true; B{|P}fN5}  
//nPos = fileAccessI.write (b,0,nRead); =?57*=]0M  
} >;QkV6i7  
catch(Exception e){e.printStackTrace ();} -)?~5Z   
} u9>.x zYG  
} "wxs  
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//打印回应的头信息 QHsS|\u  
public void logResponseHead(HttpURLConnection con) jjz<V(Sk  
{ "31GC7  
for(int i=1;;i++) }qW%=;!  
{ `2NL'O:  
String header=con.getHeaderFieldKey(i); 8\y%J!b  
if(header!=null) gzP(LfI5  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); C>@~W(IE  
Utility.log(header+" : "+con.getHeaderField(header)); RN3w{^Ll  
else .d9VV&  
break; U;6~]0^K  
} tGd9Cs9D<  
} 5D]%E?ag  
~/\;7E{8!  

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public void splitterStop() s i
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{ .$4DK*  
bStop = true; k KL^U  
} (J<@e!@NE  
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} S_6`.@B}  
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/* A@_F ;4X  
**FileAccess.java "`,PLC  
*//文件访问(定位，写) S,3e|-&$  
package NetFox; ^$_ifkkLz  
import java.io.*; +]CKu$,8  
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public class FileAccessI implements Serializable{ kzns:-a  
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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 UY{ Uo@k9x  
RandomAccessFile oSavedFile; $1\<>sJH  
long nPos; \p@,+ -gX  
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public FileAccessI() throws IOException >}O1lsjW:z  
{ X'jEI{1w  
this("",0); 0V}vVAa(B  
} m2{z
 
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public FileAccessI(String sName,long nPos) throws IOException \fU{$  
{ x7Ly,  
oSavedFile = new RandomAccessFile(sName,"rw"); ILF
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this.nPos = nPos; MJV&%E6{:{  
oSavedFile.seek(nPos); 7x-k-F3  
} u/y`M]17  
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public synchronized int write(byte[] b,int nStart,int nLen) Ej
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{ 1oj7R7  
int n = -1; WU#bA|Cf  
try{ (rZq0*  
oSavedFile.write(b,nStart,nLen); w6R
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n = nLen; DWk'6;e4j  
} {E6b/G?Q  
catch(IOException e) )J~Qx-jG  
{ I^M3>}p  
e.printStackTrace (); }
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} A[ /0on5r  
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return n; gA2\c5F<  
} XV%L6x  
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} <LZvG IMl  
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/* ,O3"r;  
**SiteInfoBean.java #hR}7K+@  
*/ A>7'W\R  
package NetFox; O%(:8nIgZ  
\RMYaI^+;  
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public class SiteInfoBean { &}:Hp9n  
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private String sSiteURL; //Site's URL X@af[J[cQ  
private String sFilePath; //Saved File's Path 4(u+YW GX  
private String sFileName; //Saved File's Name X[NsdD?w1+  
private int nSplitter; //Count of Splited Downloading File kfm8F8sxl  
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pl q$t/.U;  
public SiteInfoBean() VC>KW{&J0  
{//nSplitter的缺省值为5 dldM hT$  
//default value of nSplitter is 5 nm %ka4  
this("","","",5); z>~`9Qiw'  
} S:rW}rJ  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) zMtK_ccQ  
{ jh\q2E~,`  
sSiteURL= sURL; X?4
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sFilePath = sPath; % OiSuw  
sFileName = sName; C&<f YCwG  
this.nSplitter = nSpiltter; OX|/yw8  
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} uZmfvMr3  
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e *;"$7o9  
public String getSSiteURL() ",&}vfD4M  
{ _a15R/S  
return sSiteURL; j]Rl1~+M  
} KMoRMCT  
tEiN(KA!5  
ZW+{<XTof4  
public void setSSiteURL(String value) t4h05
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{ M9bb,`X>Q  
sSiteURL = value; `'Z ;+h]  
} Qkr'C n  
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public String getSFilePath() lmr{Ib2a  
{ Y&'2/zI6~  
return sFilePath; Am kHVg  
} C/!2q$  
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:l
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public void setSFilePath(String value) *RxbqB-  
{ G_j`6v)  
sFilePath = value; 8.Y6r  
} ^U~YG=!ww  
tJHzhH)  
`jP\*k`~]  
public String getSFileName() .~W7{SY[  
{ !WVF{L,/I  
return sFileName; q3scz  
} gyI5;il~  
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[2)Y0; ["  
public void setSFileName(String value) a&XURyp  
{ !i)?j@D  
sFileName = value; 3.R?=npA  
} NwT3e&u%|  
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public int getNSplitter() *QjFrw3  
{ Q^fli"_:  
return nSplitter; (]mN09uE  
} ,6a'x~y<r  

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~(I\O?k>H  
public void setNSplitter(int nCount) zpg*hlv  
{ 9-bDgzk   
nSplitter = nCount; WNd(X}  
} RMLs(?e  
} g<UjB  
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YdE$G>
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/* d['BtVJ  
**Utility.java s{IycTbz  
*/ )5&w  
package NetFox; ^
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p(U'c}@2
 
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public class Utility { gfih;i.pY  
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#MOEY|6  
public Utility() tOp>OoD  
{ <5C3c&sds  
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}ZvL%4jT  
} Bz7T1B&to  
^(UL$cQ>  
//线程睡眠 'H*S-d6V  
public static void sleep(int nSecond) p1G!-\l  
{ Mg^GN-l  
try{ Q !S"=2  
Thread.sleep(nSecond); V/762&2X  
} \'E%ue_<9  
catch(Exception e) /0"Y. @L  
{ /o8h1L=  
e.printStackTrace (); 7c+TS--  
} ";s?#c  
} %3z-^#B=  
s:;!QIC5jo  
//日志 Ds0^/bYp&  
public static void log(String sMsg)  b.C!4^  
{ ;uDH&3W  
System.err.println(sMsg); #Q$9Eq8"[  
} &#;UKk~)Of  
1_GUi  
MlS<txFPS  
public static void log(int sMsg) ?L{[84GSO  
{ hQ8/-#LO_  
System.err.println(sMsg); Wl::tgU  
} 1(rH5z'F  
} oh#6>|  
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/* 3Yg/-=U(  
**TestMethod.java ^aXyho  
*/ p~+)!Z#  
package NetFox; p0'A\@|  
vpOzF>O  
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public class TestMethod { A*MlK"  
H.w
p{m{  
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public TestMethod() p# O%<S@?  
{ ///xx/weblogic60b2_win.exe H4^-MSw  
try{ X^fMt]  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); x:
@HtTX  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); F/&Z1G.  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ",`fGu )  
fileFetch.start(); y=5s~7]  
} ~i6tcd  
catch(Exception e){e.printStackTrace ();} 3H@TvV/;f  
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}&`#  
} {$O.
@#'  
3EF|1B/5  
/`}C
~  
public static void main(String[] args) p4HX83y{  
{ gWgYZX  
new TestMethod(); Q[`_Y3@j  
} QfT&y &  
} (#LV*&K%IC  
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