http断点续传简单实现（java)

/* x }\64  
**SiteFileFetch.java Sp@^XmX(S  
*/ ,&jhlZ i  
package NetFox;
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import java.io.*; { /K.3  
import java.net.*; 0E,8R{e  
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public class SiteFileFetch extends Thread { !c}O5TI|#  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 5R'TcWf#W  
long[] nStartPos; //开始位置 uw[<5  
long[] nEndPos; //结束位置 ])|d"[ur=  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 4 Y;Nm1@  
long nFileLength; //文件长度 Mn9dqq~a
 
boolean bFirst = true; //是否第一次取文件 "uuVy$6C  
boolean bStop = false; //停止标志 2^mJ+v<  
File tmpFile; //文件下载的临时信息 9o;^[Ql-  
DataOutputStream output; //输出到文件的输出流 _,xc[ 07  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） KM}f:_J*lg  
public SiteFileFetch(SiteInfoBean bean) throws IOException qfL~Wp2E;  
{ Y ;u<GOe  
siteInfoBean = bean; 4wID]bKM  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 5mJJ
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); $FlW1E j  
if(tmpFile.exists ()) 'oF%,4 !Y  
{ As3.Q(#Z  
bFirst = false; l)Pu2!Ic  
read_nPos(); oFy=-p+C  
} 9:ze{ c $  
else LQtj~c>X-|  
{ |zQ4u  
nStartPos = new long[bean.getNSplitter()]; P;P%n  
nEndPos = new long[bean.getNSplitter()]; g .onTFwN  
} lJu;O/  
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} *of3:w  
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public void run() $^OvhnL/  
{ RA KFU  
//获得文件长度 d]:I(9K  
//分割文件 w8kOVN2b  
//实例FileSplitterFetch -R57@D>j\  
//启动FileSplitterFetch线程  Fy`(BF\  
//等待子线程返回 iz8Bf;  
try{ ~i~7na|  
if(bFirst) E=e*VEjy  
{ v}1QH  
nFileLength = getFileSize(); ]8Q4BW  
if(nFileLength == -1) k 8UO9r[  
{ 1u: gFUb  
System.err.println("File Length is not known!"); 6
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} E"+Q
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else if(nFileLength == -2) Svondc 4  
{ RRRCS]y7$t  
System.err.println("File is not access!"); 4*Q#0`um  
} ^.1c{0Y^0  
else 7on.4/;M  
{ ?Cl%{2omO  
for(int i=0;i<nStartPos.length;i++) AtdlZ  
{ 2] zq#6ix  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); AD1=[I3  
} 9[G[$c  
for(int i=0;i<nEndPos.length-1;i++) [x9KVd ^d  
{ 1+9W+$=h2  
nEndPos = nStartPos[i+1]; POvP]G9'"  
} ~~v3p>zRr  
nEndPos[nEndPos.length-1] = nFileLength; n^z]q;IN2.  
} {B[=?6tQ  
} 7(qE0R&@  
l-SAC3qhG  
&;+-?k|  
//启动子线程 KVD8YfF  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; [-\%4  
for(int i=0;i<nStartPos.length;i++) ^:#D0[  
{ D@Vt^_  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), >sK!F$  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), f>W-  
nStartPos,nEndPos,i); U-IpH+E  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .v$D13L(o  
fileSplitterFetch.start(); N'g>M
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} c2&q*]?l;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), <)u`~$n2  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 5qr'.m  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", b]x4o#t  
nEndPos = " + nFileLength); W0l,cOOZJ  
// fileSplitterFetch[nPos.length-1].start(); WN01h=1J_  
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//等待子线程结束 w,h`s.AN  
//int count = 0; JKGc3j,+#  
//是否结束while循环 Vm3v-=6  
boolean breakWhile = false; rd9e \%A  
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while(!bStop) Qk,I^1w?7  
{ "J4WzA%i  
write_nPos(); Vl:^>jTki  
Utility.sleep(500); hnDBFQ{  
breakWhile = true; [/Rf\T(,jn  
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for(int i=0;i<nStartPos.length;i++) Z@3i$8  
{ ynE)Xdh  
if(!fileSplitterFetch.bDownOver) cUY`97bn  
{ <Dwar>
}  
breakWhile = false; ;\=M;Zt  
break; a>GyO&+Dkg  
} 4|CtRF<L  
} %`r?c<P}  
if(breakWhile) >U%gctIg  
break; 9D7+[`r(-  
i'#E)  
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//count++; y *fDwd~  
//if(count>4) f}x.jxY?  
// siteStop(); H^s<{E0<  
} Bs O+NP  
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System.err.println("文件下载结束！"); fpFhn  
} R)mu2^  
catch(Exception e){e.printStackTrace ();} hRK/T7v  
} 1+}{8D_F  
<})2#sZO!  
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//获得文件长度 vTJ}8  
public long getFileSize() ~])t 6i  
{ @Ub"5Fl4  
int nFileLength = -1; J/[=p<I)  
try{ g7OqX \  
URL url = new URL(siteInfoBean.getSSiteURL()); gK[YQXfTy  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); @te
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httpConnection.setRequestProperty("User-Agent","NetFox"); >_|O1H./4  
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int responseCode=httpConnection.getResponseCode(); .6`9H 1  
if(responseCode>=400)
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{ (X?%^^e!  
processErrorCode(responseCode); 4}4Pyjh  
return -2; //-2 represent access is error 0@H|n^Md#  
} &N
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String sHeader; G>1eFBh }  
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for(int i=1;;i++) wPwXM!  
{ *=+td)S/1  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); *#tJM.Z  
//Utility.log(in.readLine()); <8d^^0  
sHeader=httpConnection.getHeaderFieldKey(i); <N_+=_  
if(sHeader!=null) PYM(Xz$  
{ il:$sd  
if(sHeader.equals("Content-Length")) a hR ^  
{ A-T]9f9  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 2JJ"O|Ibz  
break; L1Iz<>  
} }>
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} ,PWgH$+  
else }Ub6eXf(2  
break; XgLL!5`  
} gG-BVl"59  
} 1@QZnF5[  
catch(IOException e){e.printStackTrace ();} /+\uqF8F  
catch(Exception e){e.printStackTrace ();} dt`{!lts'  
:k.NbN$i\  
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Utility.log(nFileLength); L"{JRbh[  
;)!Sp:mHX  
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return nFileLength; +(C6#R<LI  
} U2ZD]q  
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,)iKH]lY=  
//保存下载信息（文件指针位置） :j]vf8ec  
private void write_nPos() )tl.
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{ +TQ47Zc  
try{ hA33K #bC  
output = new DataOutputStream(new FileOutputStream(tmpFile)); *g[^.Sg  
output.writeInt(nStartPos.length); /Rg*~Ers *  
for(int i=0;i<nStartPos.length;i++) >]W)'lnO  
{ > 3&: 5  
// output.writeLong(nPos); 8AnP7}n;?'  
output.writeLong(fileSplitterFetch.nStartPos); m"o ;L3  
output.writeLong(fileSplitterFetch.nEndPos); q~*t@  
} |m80]@>  
output.close(); XI9js{p  
} ,B0_MDA +  
catch(IOException e){e.printStackTrace ();} ^Nmg07_R  
catch(Exception e){e.printStackTrace ();} A` AaTP  
} Up,vD)tG  
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//读取保存的下载信息（文件指针位置） %YSu8G_t  
private void read_nPos() C
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{ o]p|-<I Q  
try{ |Tm!VFd  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 
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int nCount = input.readInt(); '*?WU_L(g  
nStartPos = new long[nCount]; -*m+(7G\  
nEndPos = new long[nCount]; }b0; 0j  
for(int i=0;i<nStartPos.length;i++) <_XWWT%  
{ 9\]^|?zQ`  
nStartPos = input.readLong(); %"af748!+D  
nEndPos = input.readLong(); IjR'Qou5  
} RW}"2  
input.close(); e}.^Tiwd]  
} k31I ysh  
catch(IOException e){e.printStackTrace ();} ^8@Iyh
  
catch(Exception e){e.printStackTrace ();} j'BMAn ?  
} ##EYH1P]  
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private void processErrorCode(int nErrorCode) dVFf.  
{ =<NljOR4`  
System.err.println("Error Code : " + nErrorCode); *H.oP  
} RhvfC5Hq  
"B8"_D&  
JGH60|  
//停止文件下载 DNj"SF(J  
public void siteStop() 2w-51tqm  
{ Hx\H $Y  
bStop = true; P
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for(int i=0;i<nStartPos.length;i++) TM|)Ljm  
fileSplitterFetch.splitterStop(); jMN[J|us51  
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{-  
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} [w&$|h:;  
} +C(/Lyo}  
//负责部分文件的抓取 EB_NK  
**FileSplitterFetch.java ea00
\  
*/ zA!0l*H  
package NetFox; w&B#goS  
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import java.io.*; *L'>U
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import java.net.*; jD`d#R  
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public class FileSplitterFetch extends Thread { Hw-Z  

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String sURL; //File URL P b]3&!a  
long nStartPos; //File Snippet Start Position e4z1`YLsG  
long nEndPos; //File Snippet End Position +5&wOgx  
int nThreadID; //Thread's ID k!KDWb  
boolean bDownOver = false; //Downing is over -~QHqU.  
boolean bStop = false; //Stop identical Gsc\/4Wx  
FileAccessI fileAccessI = null; //File Access interface Z+StB15  
3:f[gV9K  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException XFh>U7z.  
{ yGsz2T;w  
this.sURL = sURL; B-T/V-c7  
this.nStartPos = nStart; _"#!e{N|  
this.nEndPos = nEnd; V2<?ol  
nThreadID = id; \#>T~.Y7K  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /g$G_}  
} W":PG68  
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public void run() A,)VM9M_l  
{ >N?2""  
while(nStartPos < nEndPos && !bStop) b77>$[xB  
{ !Y:0c#MPH  
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try{ xGG,2W+z  
URL url = new URL(sURL); _` [h,=  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }h}<!s  
httpConnection.setRequestProperty("User-Agent","NetFox"); &V<W>Y>|l*  
String sProperty = "bytes="+nStartPos+"-"; 7oR:1DXw|  
httpConnection.setRequestProperty("RANGE",sProperty); ) 9oH,gZ  
Utility.log(sProperty); ,.o<no  
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InputStream input = httpConnection.getInputStream(); $L2%u8}8:  
//logResponseHead(httpConnection); wV)}a5+  

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byte[] b = new byte[1024]; d.2mT?`#  
int nRead; v
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) PccB]  
{ wCHR7X0*b  
nStartPos += fileAccessI.write(b,0,nRead); _HA$ j2  
//if(nThreadID == 1) Jy aag-  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Jz!Z2c  
} -.|4Y#b:&  
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C P3<1~  
Utility.log("Thread " + nThreadID + " is over!"); ~kCwJ<E  
bDownOver = true; 1H,g=Y4f%  
//nPos = fileAccessI.write (b,0,nRead); _NcYI  
} )*5G">))p  
catch(Exception e){e.printStackTrace ();} jkF8\dR  
} :EtMH(  
} '>v^6iS  
)!Bd6-  
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//打印回应的头信息 X{g%kf,D=  
public void logResponseHead(HttpURLConnection con) gLSA!#[h  
{ $y?k
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for(int i=1;;i++) =]>NDWqpHN  
{ =9LC<2  
String header=con.getHeaderFieldKey(i); f):~8_0b  
if(header!=null) R4<lln:[  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); z1!6%W_.  
Utility.log(header+" : "+con.getHeaderField(header)); oy<
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else 2 /y}a#s  
break; oR*=|B  
} K$ v"Uk  
} vLO&Lpv  
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public void splitterStop() K+T.o6+  
{ i%

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bStop = true; =_[Z W  
} ntP|\E  
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} R1-k3;v^  
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/* -K[782Q  
**FileAccess.java p[2GkP  
*//文件访问(定位，写) jvVi%k  
package NetFox; b8f+,2Tk  
import java.io.*; htPqT,L  
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lr2rQo>  
public class FileAccessI implements Serializable{ c {I"R8  
+3,|"g::  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Fpt-V  
RandomAccessFile oSavedFile; &&L"&Rc  
long nPos; ,eQ[Fi!!  
:ZxLJK9x1  
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public FileAccessI() throws IOException -s$<Op{s  
{ }xlKonk  
this("",0); +@VYs*&&  
} y5m!*=`l`  
H0*5_OJ!i  
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public FileAccessI(String sName,long nPos) throws IOException Ih1|LR/c  
{ 0W>9'Rw  
oSavedFile = new RandomAccessFile(sName,"rw"); MjaUdfx  
this.nPos = nPos; D*vm cSf  
oSavedFile.seek(nPos); ^^(<c,NX#M  
} ;5<-)  
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!5x Ly6=}  
public synchronized int write(byte[] b,int nStart,int nLen) S)%_weLW7  
{ ad!(z[F'Y  
int n = -1; ,M3z!=oIGn  
try{ |xr32gs  
oSavedFile.write(b,nStart,nLen); uv4 _:   
n = nLen; Wn!G.(Jq  
} 3z{S}~  
catch(IOException e) 4x'AC%&Qi  
{ M+sj}  
e.printStackTrace (); bO49GEUT _  
} 0zqj0   
&WZP2Q|  
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return n; a%hGZCI  
} @XOi62(  
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} -O&"|   

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/* !v!N>f4S$  
**SiteInfoBean.java iUr xJh  
*/ dDKqq(9(`  
package NetFox; L)-*,$#<oW  
n_$yV:MuT!  
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public class SiteInfoBean { b?kPN:U#N/  
L(WOet('  
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private String sSiteURL; //Site's URL Sb^ b)q"  
private String sFilePath; //Saved File's Path ma}
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private String sFileName; //Saved File's Name 6b:DJ  
private int nSplitter; //Count of Splited Downloading File ~HP LV  
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$ u2Cd4  
public SiteInfoBean() _1JmjIH)M  
{//nSplitter的缺省值为5 PI7IBI  
//default value of nSplitter is 5 6tOi^+qN  
this("","","",5); sT<{SmBF  
} E_[ONm=,  
R@r{  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 3kLOoL?  
{ XUsy.l/  
sSiteURL= sURL; oofFrAaT  
sFilePath = sPath; J>v$2?w`w  
sFileName = sName; .]Ybp2`
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this.nSplitter = nSpiltter; v#=ayWgk  
n0.8)=;2  
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} X^in};&d  
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 nhfwOS  
public String getSSiteURL() F7uhuqA]N  
{ +)-d_K.(k  
return sSiteURL; -Uf4v6A  
} Tcs3>lJ}  
v_-ls"l  
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public void setSSiteURL(String value) 3#9M2O\T  
{ H!JWc'(<$  
sSiteURL = value; EHWv3sR-  
} nx :)k-p_[  
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|p'i,.(c_W  
public String getSFilePath() K%<GU1]-]  
{ d2ofxfpg+  
return sFilePath; luF#OPC  
} OQ|,-  
a-
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--/-D5  
public void setSFilePath(String value) >H?uuzi  
{ Ao!=um5D J  
sFilePath = value; -eYL*P
a  
} |Y4q+sDW  
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public String getSFileName() Ij$)RSPtH  
{ ]xB6cPdLu  
return sFileName; {Vl"m2  
} SbJh(V-pr  
]1Qi=2'  
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public void setSFileName(String value) i-V0Lm/  
{ tD^a5qPh  
sFileName = value; 2e\Kw+(>{  
} coO.kTO;  
ULbP_y>(Y  
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public int getNSplitter() >;.*  
{ MZiF];OY  
return nSplitter; |bvGYsn_#=  
} L3>4t: 8  
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F$C+R&V_  
public void setNSplitter(int nCount) /~"AG l.  
{ '7=<#Blc  
nSplitter = nCount; U:Fpj~E_w  
} c8tP+O9  
} p(7c33SyF  
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dff#{  
/* :9O|l)N)W=  
**Utility.java `0[fLEm  
*/ SJF2k[da  
package NetFox; ~:s!].H  

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public class Utility { ep`/:iYW  
@s?oJpo  
{!tOI  
public Utility() zlN+edgY#,  
{ T)O]:v  
9Iy[E,j  
X~#@rg!"  
} `;T?9n  
td`wNy\  
//线程睡眠 cG5$lB  
public static void sleep(int nSecond) ]:Wb1  
{ cxk=| ?l  
try{ "vvFq ,c  
Thread.sleep(nSecond); s~#
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} >d)|r  
catch(Exception e) _qk9o  
{ rcpvH}N:  
e.printStackTrace (); /.f!  
} ?~]>H A:  
} }"g@E-]N  
dfXV1B5  
//日志 2voNg
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public static void log(String sMsg) Z^C!RSQ  
{ cRPr9LfD@  
System.err.println(sMsg); u'{sB5_H  
} *Y^5M"AB_  
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mr
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public static void log(int sMsg) [29$~.m$Y  
{ !/[AQ{**T!  
System.err.println(sMsg); .Pqj6Ko9  
} Iy-u`S  
} #NSaY+V  
mfUKHX5  
%Ud.SJ3  
/* jWz|K  
**TestMethod.java Ab/v_mA;  
*/ C}|O#"t^\  
package NetFox; I(F1S,7  
]q@rGD85K  
7?)m(CFy  
public class TestMethod { H74NU_  
N7%=K9  
d8 3+6d  
public TestMethod() _dz:\v  
{ ///xx/weblogic60b2_win.exe ok8JnQC
 
try{ (}~ 1{C@  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ZD iW72&Q  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); %pQdq[J={  
SiteFileFetch fileFetch = new SiteFileFetch(bean); +*]SP@|IYI  
fileFetch.start(); R?i-"JhW  
} us(sZG  
catch(Exception e){e.printStackTrace ();} "Vs Nyy  
wpJ^}+kF  
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} +G>aj'\M|  

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public static void main(String[] args) Au%Wrk3j  
{ m mw)C"  
new TestMethod(); t(Cq(.u`:  
} \v B9fA:*  
} 1WZKQeOo  
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