http断点续传简单实现（java)

/* )$MS 0[?  
**SiteFileFetch.java g+:$X- r  
*/ #N; 
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package NetFox; [fd~nD#.  
import java.io.*; }'u3U"9)  
import java.net.*; .8-PB*vb  
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public class SiteFileFetch extends Thread { [0K=I64 z  
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SiteInfoBean siteInfoBean = null; //文件信息Bean OdO{xG G@  
long[] nStartPos; //开始位置 {PL,VY)Z  
long[] nEndPos; //结束位置 BeAk21xb  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 7^HpVcSM  
long nFileLength; //文件长度 rZ pbu>S  
boolean bFirst = true; //是否第一次取文件 C=8H)Ef,l  
boolean bStop = false; //停止标志 8a7YHUL<3i  
File tmpFile; //文件下载的临时信息 QT_Srw@  
DataOutputStream output; //输出到文件的输出流 L+_8QK<  

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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） C2NzP& FD  
public SiteFileFetch(SiteInfoBean bean) throws IOException
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{ SzRL}}I  
siteInfoBean = bean;  1U  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); S<*';{5~  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); I`lDWL  
if(tmpFile.exists ()) ~H
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{ cnbo+U  
bFirst = false; HTw#U2A;+  
read_nPos(); =+`D  
} *<w3" iq  
else o.v2z~V  
{ #sL
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nStartPos = new long[bean.getNSplitter()]; 0xv\D0  
nEndPos = new long[bean.getNSplitter()]; \Ph]*%  
} @sN^BX`z  
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} "X`Qe!zk4  
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public void run() CK=ARh#|  
{ Xp#~N_S$  
//获得文件长度 /GyEVCc  
//分割文件 ZH% we  
//实例FileSplitterFetch Ohc^d"[7  
//启动FileSplitterFetch线程 hRk,vB]
 
//等待子线程返回 W.IH#`-9E  
try{ cFw3Iw"JJ  
if(bFirst) B+|IZoR  
{ %,XI]+d  
nFileLength = getFileSize(); ^+EMZFjg(  
if(nFileLength == -1) QJQJR/g  
{ D_Guc8*  
System.err.println("File Length is not known!"); n7@j}Q(&?  
} @$Yb#$/  
else if(nFileLength == -2) rj}(muM,R  
{ Mg+4huT  
System.err.println("File is not access!"); -gB{:UYi3  
} !1("(Eb  
else !W(`<d]68:  
{ lelMt=  
for(int i=0;i<nStartPos.length;i++) SGQDro=l  
{ =ydpU<aS  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); <W?WUF  
} 7O"hiDQ  
for(int i=0;i<nEndPos.length-1;i++) &h\7^=s.  
{ _OLI%o  
nEndPos = nStartPos[i+1]; yk`)
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} s_TD4~ $  
nEndPos[nEndPos.length-1] = nFileLength; XYMxG:  
} FQ1arUOFW,  
} C]M7GHe1q  
&"xQ~05  
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//启动子线程 $ND90my  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Q]^Yi1PbS  
for(int i=0;i<nStartPos.length;i++) <;aJ#qT  
{ !KAsvF,j  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), A4}#U=3tI  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), .izf#r:<  
nStartPos,nEndPos,i); %TDXF_.[  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ]b> pI;  
fileSplitterFetch.start(); (ZS/@He  
} *l:&f_ngV  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), fw
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); L*9H#%3  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", bK?MT]%}r  
nEndPos = " + nFileLength); *{Yh6{  
// fileSplitterFetch[nPos.length-1].start(); K\~v&  
^:+Rg}]W^  
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//等待子线程结束  J+lGh9G  
//int count = 0; sSz%V[XWL  
//是否结束while循环 %/Bvy*X&  
boolean breakWhile = false; 0lBat_<8  
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while(!bStop)
}DbE4"^K7  
{ 'd+
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write_nPos(); i0iez9B  
Utility.sleep(500); .N!{ U  
breakWhile = true; 6W$rY] h!  
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for(int i=0;i<nStartPos.length;i++) ?3Pazc]+|  
{ JA< :K0  
if(!fileSplitterFetch.bDownOver) qv$!\T  
{ H}B2A"  
breakWhile = false; SYeE) mI  
break; `2,a(Sk#  
} M}u1qXa  
} oE6|Zw  
if(breakWhile) Fav^^vf*1  
break; -w\M-wc/$  
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//count++; $HxS:3D%D  
//if(count>4) b9DR%hO:  
// siteStop(); GY9y9HNZ  
} o(zTNk5d  
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System.err.println("文件下载结束！"); &>g~-s  
} N2[jO+6  
catch(Exception e){e.printStackTrace ();} *Wso3 6an  
} p&\K9hfi  
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McP~}"!^  
//获得文件长度 :PUK6,"5]O  
public long getFileSize() >(OYK}ZN  
{ HS7_MGU  
int nFileLength = -1; ^&-a/'D$,  
try{
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URL url = new URL(siteInfoBean.getSSiteURL()); -,|ha>r  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
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httpConnection.setRequestProperty("User-Agent","NetFox"); _[F@1NJ  
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int responseCode=httpConnection.getResponseCode(); S~> 5INud  
if(responseCode>=400) yhwy>12,K  
{ #)`\!)?  
processErrorCode(responseCode); IkU|W3Vo  
return -2; //-2 represent access is error Dp`HeSKU^  
} &wb9_?ir-  
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String sHeader; d
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for(int i=1;;i++) f1J%]g!  
{ r6MB"4xd  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); V_f`0\[x  
//Utility.log(in.readLine()); 
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sHeader=httpConnection.getHeaderFieldKey(i); GG+5/hU  
if(sHeader!=null) xDUaHE1co  
{ P5Dk63z]  
if(sHeader.equals("Content-Length")) AEqq1A
 
{ 7`dY1.rq  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); _ eiF@G  
break; 8%-%AWF]  
} Hd374U<8]T  
} BGzO!s*@j  
else lJ&y&N<O  
break; O|7yP30?M  
} R6<4"?*r  
} Cg
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catch(IOException e){e.printStackTrace ();} H-2_j  
catch(Exception e){e.printStackTrace ();} 9n 6fXOC  
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Utility.log(nFileLength); SOj`Y|6^:  
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return nFileLength; 1`QsW&9=b  
} lQL:3U0DjU  
:Y^I]`lR"  
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//保存下载信息（文件指针位置） PQ3h\CL1n  
private void write_nPos() dyO E6Ex  
{ fI]bzv;  
try{ qtY m!g  
output = new DataOutputStream(new FileOutputStream(tmpFile)); \8>oJR 6  
output.writeInt(nStartPos.length); F@EJtwLd5y  
for(int i=0;i<nStartPos.length;i++) >A=\8`T^  
{ 8lb-}=  
// output.writeLong(nPos); <xqba4O  
output.writeLong(fileSplitterFetch.nStartPos); I7zn>^0}  
output.writeLong(fileSplitterFetch.nEndPos); JiA'BEJN  
} v)+@XU2wZ  
output.close(); uy9!qk  
} ]Uh1l.O  
catch(IOException e){e.printStackTrace ();} 11{y}J  
catch(Exception e){e.printStackTrace ();} !^L-T?y.2  
} )*D'csGc  
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//读取保存的下载信息（文件指针位置） pX_b6%yX(  
private void read_nPos() F~R7~ZE  
{ +$,d
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try{ >|nt2  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); HTR1)b  
int nCount = input.readInt(); 7xT[<?,  
nStartPos = new long[nCount]; Ow)R|/e/  
nEndPos = new long[nCount]; R&Ci/  
for(int i=0;i<nStartPos.length;i++) no|Gq>Xp  
{ TY6 rwU  
nStartPos = input.readLong(); |[LE9Lq/  
nEndPos = input.readLong(); jyQVSQs  
} ,C:o`fQ\  
input.close(); $3#%aA!(#  
} C{&)(#*L  
catch(IOException e){e.printStackTrace ();} K'Spbn!nC  
catch(Exception e){e.printStackTrace ();} 0H+c4IW  
} #8U
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private void processErrorCode(int nErrorCode) -l[jEJS}  
{ km4g}~N</  
System.err.println("Error Code : " + nErrorCode); 9I kUZW  
} 9|3o<  
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zo44^=~%  
//停止文件下载 hVf^  
public void siteStop() ERC<Dd0  
{ =fWdk\Wv  
bStop = true; vi|Zit  
for(int i=0;i<nStartPos.length;i++) >UWStzH<  
fileSplitterFetch.splitterStop(); ZAeQ~
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} ! Rvn'|!  
} e1uMR-Q  
//负责部分文件的抓取 Pb4q`
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**FileSplitterFetch.java ]3+``vL  
*/ 5Eal1Qu  
package NetFox; }p*?1N  
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import java.io.*; GX5W^//}  
import java.net.*; liD47}+  
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public class FileSplitterFetch extends Thread { S&01SX6  
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String sURL; //File URL rS,j;8D-  
long nStartPos; //File Snippet Start Position
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long nEndPos; //File Snippet End Position p8>R#9  
int nThreadID; //Thread's ID (:OHyeNt  
boolean bDownOver = false; //Downing is over ohsH2]C  
boolean bStop = false; //Stop identical qiU5{}  
FileAccessI fileAccessI = null; //File Access interface :kN5?t=  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException QnU0"_-  
{ r--;yEjWE  
this.sURL = sURL; Fr;lG  
this.nStartPos = nStart; $T/#1w P  
this.nEndPos = nEnd; Yrsp%<qj  
nThreadID = id; =GTD"*vwr  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 _[JkJwPTx  
} 4=s9A  
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public void run() S.hC$0vrj  
{ <I1y  
while(nStartPos < nEndPos && !bStop) 045\i[l=  
{ L=m:/qQL  
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try{ 5[<F_"x  
URL url = new URL(sURL); OpqNEo\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); GA ik;R  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8f-:d]  
String sProperty = "bytes="+nStartPos+"-"; ;dOs0/UM&  
httpConnection.setRequestProperty("RANGE",sProperty); @G(xaU'u  
Utility.log(sProperty); JCcQd01z  
{,Fcd(MU  
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InputStream input = httpConnection.getInputStream(); Q"'V9m7 i  
//logResponseHead(httpConnection); z
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byte[] b = new byte[1024]; eJ:Yj ~X`<  
int nRead; NQR^%<hU  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) pns+y  
{ 1MV
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nStartPos += fileAccessI.write(b,0,nRead); !;+U_j'Pg  
//if(nThreadID == 1) ob]dZ  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ] R<FKJ[  
} 2Y;!$0_rv  
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Utility.log("Thread " + nThreadID + " is over!"); H!. ZH(asY  
bDownOver = true; '=@r7g.2  
//nPos = fileAccessI.write (b,0,nRead); H+R7X71{  
} yZ~b+=UM  
catch(Exception e){e.printStackTrace ();} x ^[F]YU  
} 4oN${7k0  
} ~v\hIm3=m  
s ^3[W0hL  
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//打印回应的头信息 3G.r-  
public void logResponseHead(HttpURLConnection con) 1 KB7yG-#6  
{ #B}Qt5w  
for(int i=1;;i++) Jh^8xI,`C  
{ [-]A^?yBM  
String header=con.getHeaderFieldKey(i); _25d%Ne0  
if(header!=null) e{JVXc[D  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 6WO7+M;z  
Utility.log(header+" : "+con.getHeaderField(header)); :])Ja
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else 6e/7'TYwT  
break; 8sWr\&!  
} yl]UUBcQ  
} #]X2^ND47  
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public void splitterStop() (Xj.iP  
{ >|(%2Zl  
bStop = true; pX^=be_  
} f)U6p  
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} Ph Ttx(!  
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/* IhwN],-V  
**FileAccess.java 2!idy]vy_  
*//文件访问(定位，写) Mlwdha0  
package NetFox; !3?yG  
import java.io.*; +0dT^Jkqg  
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public class FileAccessI implements Serializable{ c(E,&{+E  
/:KQAM0  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节
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RandomAccessFile oSavedFile; tJz^DXqAc  
long nPos; {!y<<u1  
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public FileAccessI() throws IOException MISE C[/  
{ @sdS0pC  
this("",0); 19) !$Hl  
} R|-j]Ne  
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public FileAccessI(String sName,long nPos) throws IOException L W?&a3e  
{ V $>"f(  
oSavedFile = new RandomAccessFile(sName,"rw"); ~ttKI4  
this.nPos = nPos; ]xYayN!n  
oSavedFile.seek(nPos); 3AvcJ1  
} Oi
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public synchronized int write(byte[] b,int nStart,int nLen) G\):2Qz!|  
{ ;&q]X]bJ  
int n = -1; ?l>e75V%w  
try{ 2$3kKY6$e  
oSavedFile.write(b,nStart,nLen); aTX]+tBoe  
n = nLen; /xJY7yF  
} *.xZfi_|  
catch(IOException e) VT Vm7l  
{ BPqwDjW  
e.printStackTrace (); g/6nwa  
} a 1NCVZ  
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return n; T*8_FR<  
} ;NBT 4  
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} N:d D*[QZ  
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/* `P#8(GU  
**SiteInfoBean.java dbg|VoNf  
*/ tgc@7  
package NetFox; ea>[BB3#  
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public class SiteInfoBean { <jg8y'm@0  
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@|Z*f\  
private String sSiteURL; //Site's URL
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private String sFilePath; //Saved File's Path -GK'V  
private String sFileName; //Saved File's Name 5vYsA1Z
 
private int nSplitter; //Count of Splited Downloading File 3/:LYvM<  
>d'EInSF  
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public SiteInfoBean() jzQ9zy_  
{//nSplitter的缺省值为5 xTGP  
//default value of nSplitter is 5 cK/PQs
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this("","","",5); G;Us-IRZ  
} 1O|RIv7F[/  
O.dux5lfBd  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Dxz5NW4  
{ C CLfvex  
sSiteURL= sURL; eK\|SQb  
sFilePath = sPath; py}.00it  
sFileName = sName; 0@:Y>qVa  
this.nSplitter = nSpiltter; O~nBz):2  
3
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} G[y&`Qc)G  
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public String getSSiteURL() *1R##9\jU7  
{ ~>.awu+o|  
return sSiteURL; neK*jdaP  
} ,o4r,.3[s  
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public void setSSiteURL(String value) _,11EeW@  
{ iZsau2K  
sSiteURL = value; #/\pUK~km  
} u!m,ilAnd  
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public String getSFilePath() {K<~ vj;  
{ Hf!9`R[  
return sFilePath; b,=,px  
} ;jp6 }zfI  
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public void setSFilePath(String value) X
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{ .LWOM8)  
sFilePath = value; |^ 2rtI  
} QJ[(Y@ O6a  
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ru#T^AI*^  
public String getSFileName() Z $ p^v*y  
{ )6PJ*;p-  
return sFileName; ,?P8m"  
} Lw!?T(SK  
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public void setSFileName(String value) 2<p5_4"-U*  
{ @1/Q  
sFileName = value; $71i+h]_  
} fhVbJU  
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public int getNSplitter() olUqBQ&ol  
{ #fJ/KY
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return nSplitter; uzat."`d'  
} _|Y.!ZRYP  
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public void setNSplitter(int nCount) IMl9\U  
{ b(+w.R(+Ti  
nSplitter = nCount; ,%"
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} g
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} BH.:_Qrbh[  
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9n06n$F  
/* l}U~I 3}).  
**Utility.java [)C)p*!Y)  
*/ c,b`N0dOKL  
package NetFox; c,g]0S?gu  
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public class Utility { ?qq!%4mTB  
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public Utility() "@UU[o  
{ $1Q3Y'Q9  
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} /j=DC9_  
,}xpYq_/  
//线程睡眠 Vq)|gF[6i  
public static void sleep(int nSecond) #`YxoY`  
{ z=- 8iks|  
try{ 4iL.4Uj{N  
Thread.sleep(nSecond); ~T;ajvJ  
} P?WT)C2)u  
catch(Exception e) $=@9 D,R  
{ h4$OXKme?  
e.printStackTrace (); C+Fh$  
} `uaD.m$EJ  
} cNuuz
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'6dD^0dZ  
//日志 Jq$6$A,f  
public static void log(String sMsg) softfjl&l  
{ '.}6]l  
System.err.println(sMsg); yNb

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} utFcFdX  
.:r2BgL  
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public static void log(int sMsg) qxg7cj2  
{ 7~%  
System.err.println(sMsg); Uy_}@50"l  
} LB64W ;#h  
} P?3YHa^up  
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/* cx1WGbZ  
**TestMethod.java jl 30\M7  
*/ sJjl)Qs)T  
package NetFox; ECE{xoc  
mPw56>  
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public class TestMethod { 8h@)9Q]d\  
l/y Kc8^<  
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public TestMethod() &EbD.>Ci  
{ ///xx/weblogic60b2_win.exe ;s!ns N  
try{ TGt1d  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); #:Sy`G6!?  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); -G^t-I  
SiteFileFetch fileFetch = new SiteFileFetch(bean); L(!!7B_,  
fileFetch.start(); NdXy%Q  
} kp<}  
catch(Exception e){e.printStackTrace ();} yEw"8u'  
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} 3 DO$^JJ.  
1>*UbV<R;u  
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public static void main(String[] args) rz%[o,s  
{ A aF5`  
new TestMethod(); kgbr+Yw2X  
} >1)@n3.<O  
} 1X!f!0=g+  
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