http断点续传简单实现（java)

/* fnLR  
**SiteFileFetch.java f
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*/ XPHQAo[(s  
package NetFox; r.^0!(d  
import java.io.*; PtQQZ"ept  
import java.net.*;
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public class SiteFileFetch extends Thread { L Yh@ u1p  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Q  `e~MD  
long[] nStartPos; //开始位置 >:w?
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long[] nEndPos; //结束位置 c8^+^.=pX  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 tyc8{t#Z  
long nFileLength; //文件长度 WW@JVZxK  
boolean bFirst = true; //是否第一次取文件 MxM](ew~7  
boolean bStop = false; //停止标志 |Hx%f  
File tmpFile; //文件下载的临时信息 =8$|_  
DataOutputStream output; //输出到文件的输出流 m.1LxM$8  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） x2 w8zT6M  
public SiteFileFetch(SiteInfoBean bean) throws IOException 07.nq;/R  
{ aqcFY8b '  
siteInfoBean = bean; "-G&=(  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); u/z,92mmS  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); P_,v5Qx"-  
if(tmpFile.exists ()) ??|d=4g\  
{ Ivz+Jjw  
bFirst = false; J}x>~?W  
read_nPos(); 4^ c!_K&&  
} x1|Da$2  
else [Xxw]C6\>(  
{ ^7i^ \w0  
nStartPos = new long[bean.getNSplitter()]; e(?:g@]-r  
nEndPos = new long[bean.getNSplitter()]; 6?53q e  
} |$YyjYK  
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} ,]0S4h67  
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public void run() Oamv9RyDvC  
{ 4 hL`=[AB  
//获得文件长度 zt7_r`#z  
//分割文件 hNH.G(l0  
//实例FileSplitterFetch x7vq?fP0n  
//启动FileSplitterFetch线程 XxmJP5  
//等待子线程返回 "nVK< Vd  
try{ aXRv}WO$>k  
if(bFirst) +n@f'a">  
{ /)sDnJ1r  
nFileLength = getFileSize(); * eA{[  
if(nFileLength == -1) zl0;84:H  
{ t[%x}0FP-F  
System.err.println("File Length is not known!"); zx ct(  
} q]F4Lq(  
else if(nFileLength == -2) 6kP7  
{
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System.err.println("File is not access!"); %p<$|'  
} (F/HU"C  
else P;j&kuW|zL  
{ :lgHL3yl  
for(int i=0;i<nStartPos.length;i++) EC<5M5Lc  
{ q_-ma_F#s  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); -<8B,  
} ]PeLcB  
for(int i=0;i<nEndPos.length-1;i++) ZH\0=l)  
{ yPSVwe|g  
nEndPos = nStartPos[i+1]; 66/Z\H^d  
} E^7C _JP  
nEndPos[nEndPos.length-1] = nFileLength; DP|TIt,Rl  
} "]v uD  
} I%SuT7"Do  
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//启动子线程 l+t #"3  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; JRD8Lz]Q3  
for(int i=0;i<nStartPos.length;i++) UMT\Q6p  
{ k}X[u8A  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), U9x4j_.q  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), pfR"s:#  
nStartPos,nEndPos,i); +eU`H[iu  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?2/uSG|  
fileSplitterFetch.start(); *nLIXnm  
} v5B" A"N  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), R
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Sc$gnUYD{  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", q1H~ |1  
nEndPos = " + nFileLength); 9t#P~>:jY}  
// fileSplitterFetch[nPos.length-1].start(); FQ U\0<
5  
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//等待子线程结束 mU50pM~/i  
//int count = 0; ]+mjOks~  
//是否结束while循环 r)Or\HL  
boolean breakWhile = false; WPtMds4  
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while(!bStop)  -H`\? R  
{ ]\7lbLv  
write_nPos(); X R4)z  
Utility.sleep(500); [$^A@bqk  
breakWhile = true; Np$z%ewK.  
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for(int i=0;i<nStartPos.length;i++) ^/k,  
{ R'L?Xn}3  
if(!fileSplitterFetch.bDownOver) * flWL  
{ #Gd7M3  
breakWhile = false; B=r0?%DX"1  
break; TiQ^}5~M  
} lw s(/a*c  
} {$0&R$v3  
if(breakWhile) !Qcir&]C>  
break; ]dq5hkjpU  
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//count++; wDMjk2YN  
//if(count>4) Ssw&'B|o  
// siteStop();  +tIz[+u  
} Nl {7  
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System.err.println("文件下载结束！"); o*-9J2V=J  
} -3` "E%9  
catch(Exception e){e.printStackTrace ();}  La9r  
} a&C.=  
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R
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//获得文件长度 '#A:.P  
public long getFileSize() Xk?R mU6  
{ qc
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int nFileLength = -1; y+A{Y  
try{ tfA}`
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URL url = new URL(siteInfoBean.getSSiteURL()); c yP,[?N  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); H'Ln P>@n#  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8bt53ta  
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int responseCode=httpConnection.getResponseCode(); ;gUXvx~~r  
if(responseCode>=400) 8aZ$5^z  
{ Pxqiv9D<R  
processErrorCode(responseCode); =-Nsc1&  
return -2; //-2 represent access is error ~,gLplpG0  
} Hx
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String sHeader; (i]Z|@|)  
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for(int i=1;;i++) &{ZSE^  
{ 4jGLAor|  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); U(*yL-  
//Utility.log(in.readLine()); csDQva\  
sHeader=httpConnection.getHeaderFieldKey(i); w12}Rn8  
if(sHeader!=null) m2O&2[g  
{ Pw{"_g  
if(sHeader.equals("Content-Length")) krjN7&  
{ @1g&Z}L o  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 4H-j .|e  
break; kYlg4 .~M  
} oRq3 pO}f  
} .,M;hu
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else L M /Ga  
break; Jq)U</  
} /H)Br~ l  
} {cR=N~_EO  
catch(IOException e){e.printStackTrace ();} Rh<N);Sl7  
catch(Exception e){e.printStackTrace ();} +c) TDH  
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Utility.log(nFileLength); mxp Y&Y  

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return nFileLength; 8W -@N  
} xA #H0?a]  
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6
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//保存下载信息（文件指针位置） kZxW"2  
private void write_nPos() k>5O`Y:  
{ ;LQ9#M?  
try{ CGZ^hoh/  
output = new DataOutputStream(new FileOutputStream(tmpFile)); opD-vDa h  
output.writeInt(nStartPos.length); bX2"89{  
for(int i=0;i<nStartPos.length;i++) 74f9|~%  
{ ARWZ; GX  
// output.writeLong(nPos); * t!r@k  
output.writeLong(fileSplitterFetch.nStartPos); %4,?kh``D  
output.writeLong(fileSplitterFetch.nEndPos); HnU Et/  
} d~Mg vh'  
output.close(); i_
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} 7
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catch(IOException e){e.printStackTrace ();} JJnYOau  
catch(Exception e){e.printStackTrace ();} j
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} @Y-TOCadT  
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//读取保存的下载信息（文件指针位置） l r~gG3  
private void read_nPos() hs(W;tR@W  
{ ;LMWNy4  
try{ c1%rV`)]  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); _|zBUrN  
int nCount = input.readInt(); 62\&RRB i  
nStartPos = new long[nCount]; XYfv(y  
nEndPos = new long[nCount]; %|+E48  
for(int i=0;i<nStartPos.length;i++) PJ q yvbD  
{ LchnBtjn  
nStartPos = input.readLong(); v}[dnG  
nEndPos = input.readLong(); ZnfNQl[  
} n7l%gA*  
input.close(); d,9`<1{9  
} cdTsRS;E  
catch(IOException e){e.printStackTrace ();} YI@Fhr &NU  
catch(Exception e){e.printStackTrace ();} JhX=l-?  
} OYmi?y\  
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private void processErrorCode(int nErrorCode) FWY2s(5p  
{ IIz0m3';+  
System.err.println("Error Code : " + nErrorCode);  }roG(  
} AK-}V4C/A  
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//停止文件下载 <Q5Le dN  
public void siteStop() =6T 4>rP  
{ Cifd21v4  
bStop = true; I%lE;'x  
for(int i=0;i<nStartPos.length;i++) -
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fileSplitterFetch.splitterStop(); G>z,#Xt  
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} ig_2={Q@  
} ;[$n=VX`  
//负责部分文件的抓取 -<f;l_(  
**FileSplitterFetch.java n$["z w  
*/ %y<]Yzv.  
package NetFox; jirbUl  
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import java.io.*;  ux-CpI  
import java.net.*; ~<9{#uM  
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public class FileSplitterFetch extends Thread { tE"Si<[]H$  
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String sURL; //File URL Vpp&|n9^  
long nStartPos; //File Snippet Start Position Y+-xvx :  
long nEndPos; //File Snippet End Position 6Bt=^~d  
int nThreadID; //Thread's ID <4`eQ
 
boolean bDownOver = false; //Downing is over -1r2K  
boolean bStop = false; //Stop identical +K$NAT  
FileAccessI fileAccessI = null; //File Access interface C)
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException #kmh:P  
{ _GoVx=t   
this.sURL = sURL; KL?)akk  
this.nStartPos = nStart; Pz"`MB<'Ik  
this.nEndPos = nEnd; A74920X`W  
nThreadID = id; l!~
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 $2#7D* Rx  
} NPjv)TN}3  
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public void run() b
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{ 0GXO&rCG  
while(nStartPos < nEndPos && !bStop) q6q1\YB  
{ "ZMkL)'7-  
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try{ 8im@4A+n`  
URL url = new URL(sURL); /VTM 9)u  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); y'M#z_.z  
httpConnection.setRequestProperty("User-Agent","NetFox"); B]iP't\~  
String sProperty = "bytes="+nStartPos+"-"; 0E/:|k  
httpConnection.setRequestProperty("RANGE",sProperty); _|{aC1Y!V  
Utility.log(sProperty); !?FK We  
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InputStream input = httpConnection.getInputStream(); C!x/ ^gw  
//logResponseHead(httpConnection); E^Gg '
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byte[] b = new byte[1024]; C;rG]t^%  
int nRead; l=P'B @,  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop)  _^t-9  
{ {Gi h&N  
nStartPos += fileAccessI.write(b,0,nRead); GA3sRFZdQ  
//if(nThreadID == 1) =U-r*sGLN  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _}Ps(_5D  
} oQ2KW..q  
<:;^'x>!  
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Utility.log("Thread " + nThreadID + " is over!"); mDMt5(. 
 
bDownOver = true; h{iEZ#  
//nPos = fileAccessI.write (b,0,nRead); aP()|js  
} ^ @=^;nB  
catch(Exception e){e.printStackTrace ();} w!3>N"em  
} /2uQCw&x-  
} +Ov2`O8?  
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//打印回应的头信息 oduDA:  
public void logResponseHead(HttpURLConnection con) y=sGe!^  
{ 9s$U%F6}  
for(int i=1;;i++) G*8GGWB^a  
{ X" R<J#4  
String header=con.getHeaderFieldKey(i); mxG]kqi  
if(header!=null) /!xF?OmVd  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); +C{p%`<  
Utility.log(header+" : "+con.getHeaderField(header)); A}VYb:u/  
else 8HErE<_(  
break; %@J1]E;  
} "5|Lz)=  
} ^HA %q8| n  
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public void splitterStop() [J#1Ff;  
{ Bx~[F  
bStop = true; Ubz"rCjq  
} viaJblYj(f  
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} %Kb9tHg  
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/* l:(Rb-Wy  
**FileAccess.java 6tjcAsV  
*//文件访问(定位，写) CQg X=!q  
package NetFox; wzWbB2Mb5  
import java.io.*; j) vlM+  
u:
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public class FileAccessI implements Serializable{ r64u31.)  
! T9
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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 Yxd X#3  
RandomAccessFile oSavedFile; -p,x&h,p  
long nPos; b'@we0V@S  
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public FileAccessI() throws IOException Xh+ia#K  
{ hZ\+FOx;  
this("",0); 8nNsrat  
} C'mL&  
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public FileAccessI(String sName,long nPos) throws IOException c9Es%@]  
{ rnm03 '{  
oSavedFile = new RandomAccessFile(sName,"rw"); MQ/ A]EeL  
this.nPos = nPos; adEJk  
oSavedFile.seek(nPos); q 2?X"!  
} 6vzk\n  
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public synchronized int write(byte[] b,int nStart,int nLen) mryN}  
{  $6>?;  
int n = -1; 6gO9 MQY  
try{ GJ(d
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oSavedFile.write(b,nStart,nLen); CZ{k@z
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n = nLen; VL( <  
} V,7%1TZ:  
catch(IOException e) mz7l'4']+  
{ wwd'0P`/  
e.printStackTrace (); 2h^WYpCm  
} t` ^Vb-  
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return n; (zo^Nn9VJ  
} b B  
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} /i|z.nNO  
': F}3At  
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/* 8Z#j7)G  
**SiteInfoBean.java eARk QV  
*/ ZDLMMXx>  
package NetFox; Bd0eC#UGkQ  
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public class SiteInfoBean { /M0/-pV9  
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7hNb/O004  
private String sSiteURL; //Site's URL /L=(^k=a.;  
private String sFilePath; //Saved File's Path 3HV%4nZLf  
private String sFileName; //Saved File's Name qB6dFl\ (  
private int nSplitter; //Count of Splited Downloading File <|6%9@  
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public SiteInfoBean() tl8O6`<Z  
{//nSplitter的缺省值为5 .q`{Dgc~  
//default value of nSplitter is 5 P<dy3;  
this("","","",5); VkmRh,T  
} D@Da0  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ~fN%WZ;_  
{ 2i=H"('G)+  
sSiteURL= sURL; PK6iY7Qp)  
sFilePath = sPath; #} ,x @]
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sFileName = sName; ~XM[>M\qB  
this.nSplitter = nSpiltter; 8}p8r|d!ls  
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} 0OZMlt%z  
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public String getSSiteURL() !F4;_A`X  
{ J
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return sSiteURL; 3 pWM~(#>-  
} H-t|i  
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hXL|22>w<  
public void setSSiteURL(String value) U5ZX78>a  
{ qc-,+sn(  
sSiteURL = value; GY!C|7kN  
} h^|5|l  
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public String getSFilePath() j.?:Gaab?#  
{ w_-+o^  
return sFilePath; 1TJ0D_,  
} s&PM,BFf  
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cSD{$B:  
public void setSFilePath(String value) 93%{scrm  
{ <-C!;Ce{  
sFilePath = value; BNm4k7 ]M  
} 7ETjn)%bs  
h BMH)aU  
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public String getSFileName() JNU/`JN9f  
{ I2Ev~!  
return sFileName; TRvZ  
} cgZaPw2 bw  
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public void setSFileName(String value) n@>wwp  
{ f[~1<;|-  
sFileName = value; -E>)j\{PX7  
} A*]$
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8v_C5d\  
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public int getNSplitter() wrv5V M}  
{ W:s@L#-  
return nSplitter; **;p(CI  
} 7} O;FX+x  
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public void setNSplitter(int nCount) 'ig, ATY  
{ v"lf-c  
nSplitter = nCount; gT52G?-  
} 4YA./j%'  
} ur%$aX)  
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/* 'imU`zeo  
**Utility.java p]|LV)R n  
*/ *o?i:LE]  
package NetFox; a:!uORQby  
pa/9
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public class Utility { ~9M!)\~  
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public Utility() &w\I<J`T  
{ yXfMzG  
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} H#(<-)j0_  
"ED8z|]j  
//线程睡眠 :{}_|]>K  
public static void sleep(int nSecond) .KA V)So"  
{ |ng%PQq)  
try{ '1+.t$"/tU  
Thread.sleep(nSecond); R 1zC.m  
} F'W> 8  
catch(Exception e) Hcv u7uD  
{ d0UZ+ RR#  
e.printStackTrace (); knHv?#  
} [#b2%G1  
} v<h;Di@  
 W'/>et  
//日志 L]bVN)JU  
public static void log(String sMsg) <0j{ $.  
{ Ol+Kp!ocY  
System.err.println(sMsg); v|@1(  
} Y`li> .\  
>)Dhi+D  
,;iA2  
public static void log(int sMsg) JeQ[qQ  
{ s-D?)  
System.err.println(sMsg); ([pSVOnIz  
} o
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} rxE&fjW  
0D3OE.$0  
t
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/* [X"
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**TestMethod.java VTw/_Hf2p  
*/ ~ =.CTm]vf  
package NetFox; iCi>zJ  
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hPO>,j^  
public class TestMethod { Q<=Y  
O%$O(l  
:JV\){P  
public TestMethod() .h8M  
{ ///xx/weblogic60b2_win.exe CT"Fk'B'  
try{ k|j:T[_  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 5si}i'in  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 7'.s7& '7  
SiteFileFetch fileFetch = new SiteFileFetch(bean); %C*^:\y  
fileFetch.start(); gGbI3^r#  
} PrnrXl S  
catch(Exception e){e.printStackTrace ();} n`<S&KP|  
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xZ ;bMxZ  
} 3M*Y= ?pI  
[j0w\{  
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public static void main(String[] args) \y~)jq:d"  
{ n7iE8SK|k  
new TestMethod(); {nRUH*(d9  
} I'A:J  
} eP|)SU  
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