http断点续传简单实现（java)

/* "7d_$.Z  
**SiteFileFetch.java .)Q'j94Q  
*/ e~1??k.;=  
package NetFox; ~EymD *  
import java.io.*; x :s-\>RcA  
import java.net.*; 60m1 >"  
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public class SiteFileFetch extends Thread { /T0|<r!c  
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SiteInfoBean siteInfoBean = null; //文件信息Bean I[/u5V_b'  
long[] nStartPos; //开始位置 ]dH;+3}  
long[] nEndPos; //结束位置 gw-l]@;1  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 [Fe5a  
long nFileLength; //文件长度 *@< jJP4  
boolean bFirst = true; //是否第一次取文件 ;)*Drk*t,  
boolean bStop = false; //停止标志 z]pH'c39
 
File tmpFile; //文件下载的临时信息 .nnA
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DataOutputStream output; //输出到文件的输出流 L))
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） A-kI_&g\Og  
public SiteFileFetch(SiteInfoBean bean) throws IOException dCBJV  
{ 3Dy.mtP  
siteInfoBean = bean; |1EM )zh6  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ZCa?uzeo]  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); DY%E&Vd:h  
if(tmpFile.exists ()) N9hBGa$  
{ My)/d]a  
bFirst = false; K.k=\N  
read_nPos(); )%0#XC^/X5  
} 6<2 7}S  
else dS-
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{ %NKf@If)  
nStartPos = new long[bean.getNSplitter()]; m$3&r2vgi  
nEndPos = new long[bean.getNSplitter()]; i;cqK&P;]  
} XWk^$"  
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} 6HyQm?c>a  
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public void run() r>5,U:6Q/  
{ `.@N9+Aj  
//获得文件长度 N[Fz6,ZG _  
//分割文件 cxVnlgq1  
//实例FileSplitterFetch +Oo>V~  
//启动FileSplitterFetch线程 Rgg(rF=K6  
//等待子线程返回 ]R(=)  
try{ +~HL"Vv  
if(bFirst) MSu_*&j9T  
{ 94Are<  
nFileLength = getFileSize(); TRa|}JaI"  
if(nFileLength == -1) qWdL|8  
{ ^+I{*0{/[  
System.err.println("File Length is not known!"); E`BL3+kQ  
} \G2&   
else if(nFileLength == -2)
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{ |GLa`2q|  
System.err.println("File is not access!"); yy@g=<okt\  
} =*fOej>G  
else n"*A.  
{ "4Cb dD//  
for(int i=0;i<nStartPos.length;i++) h",kA(+P  
{ du Pzt  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); B\`4TU}kE  
} ; &$djP  
for(int i=0;i<nEndPos.length-1;i++) }9=VhC%J  
{ Zgd| J T7  
nEndPos = nStartPos[i+1]; s:CsUl|  
} `*^ f =y  
nEndPos[nEndPos.length-1] = nFileLength; %8s$l'Q;  
} 0@k)Cz[0;  
} .*+%-%CbP  
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#!qa#.Yi  
//启动子线程 ,ir(~g+{g  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; M|xd9kA^  
for(int i=0;i<nStartPos.length;i++) `ZhDoLpH<  
{ K?`Fpg(  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Fu].%`*xJ  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), DvhJkdLB>  
nStartPos,nEndPos,i); Gf*|f"O  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 3@7IY4>o  
fileSplitterFetch.start(); KP
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} _P,3~ ;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), F|nJ3:v  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); UaG })  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", @'P\c   
nEndPos = " + nFileLength); P3Ocfpf Bp  
// fileSplitterFetch[nPos.length-1].start(); 4;_aFn  
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U~H]w,^  
//等待子线程结束 ,X^I]]  
//int count = 0; TuR.'kE@  
//是否结束while循环 ?y"=jn  
boolean breakWhile = false; q.I  
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while(!bStop) qGivR
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{ |&wwH&<[z  
write_nPos(); iTUOJ3V7i  
Utility.sleep(500); 3FetyWl'  
breakWhile = true; !I)wI~XF)5  
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for(int i=0;i<nStartPos.length;i++) L JW0UF|  
{ V\|V1c  
if(!fileSplitterFetch.bDownOver) ]&+,`1_q  
{ ku*H*o~  
breakWhile = false; Wks?9)Is  
break; 6Z,GD  
} HnlCEW,^o  
} L>@:Xo@  
if(breakWhile) V;@kWE>3  
break; &[#iM0;)W0  
xZ84q'i"  
A*x3O%zH  
//count++; `bAOhaB,/  
//if(count>4) 25R6>CXsi  
// siteStop(); #]SiS2lM#  
} x b6X8:  
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System.err.println("文件下载结束！"); FV~ENpncP  
} x%]5Q/|Ur  
catch(Exception e){e.printStackTrace ();} vHmsS\\~9  
}
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//获得文件长度 ;:Kd?Tz$  
public long getFileSize() A,fPl R  
{ Gq)E,Ln&d  
int nFileLength = -1; veq.48E]  
try{ <h"07.y  
URL url = new URL(siteInfoBean.getSSiteURL()); P,RdYM06  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _+=M)lPm  
httpConnection.setRequestProperty("User-Agent","NetFox"); V(#z{!  
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int responseCode=httpConnection.getResponseCode(); oj$^87KX  
if(responseCode>=400) A(2!.Y 2?*  
{ rb_FBa%  
processErrorCode(responseCode); ?yNg5z  
return -2; //-2 represent access is error pVN) k  
} (U?*Z/  
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String sHeader; j84g6;4Dv  
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for(int i=1;;i++) N"k IQe*}1  
{ I
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); %pd-{KR  
//Utility.log(in.readLine()); @a]O(S>Ub  
sHeader=httpConnection.getHeaderFieldKey(i); }<=4A\LZ  
if(sHeader!=null) ,Nk{AiiN  
{ 5&V
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if(sHeader.equals("Content-Length")) \+3P<?hD#  
{ =k0qj_  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 'n$TJp|s  
break; QA"mWw-Ds  
} $-#|g  
} $C^tZFq  
else oU
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break; F?y4 L9|e  
} aMq|xHZ  
} ]I
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catch(IOException e){e.printStackTrace ();} 3;-P(G@  
catch(Exception e){e.printStackTrace ();} @!np 0#  
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Utility.log(nFileLength); jM07&o]D  
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return nFileLength; Bsc&#  
} _VM()n;  
}@Dgr)*+  
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//保存下载信息（文件指针位置） Dn
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private void write_nPos() G[4$@{
  
{ #[LnDU8
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try{ yE{(Ebm  
output = new DataOutputStream(new FileOutputStream(tmpFile)); %V;B{?>9zB  
output.writeInt(nStartPos.length); A@81wv  
for(int i=0;i<nStartPos.length;i++) ;&$Nn'~a  
{ d!z}! :  
// output.writeLong(nPos); kuI%0)iZn  
output.writeLong(fileSplitterFetch.nStartPos); y7Sey;  
output.writeLong(fileSplitterFetch.nEndPos); WJ[ybzVj  
} K.P1|  
output.close(); ^$VH~i&  
} m2esVvP  
catch(IOException e){e.printStackTrace ();} ^V;h>X|  
catch(Exception e){e.printStackTrace ();} b,r{wrLe)  
} XUK!1}  
7}%
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//读取保存的下载信息（文件指针位置） Jb1L[sT2  
private void read_nPos() h,!`2_&UQ  
{ Hsl0|jy(/  
try{ /$Ca}>  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); e]Q bC"  
int nCount = input.readInt(); ?y`we6~\1  
nStartPos = new long[nCount]; S?BI)shmg  
nEndPos = new long[nCount]; KP*cb6vA  
for(int i=0;i<nStartPos.length;i++) +J;T= p  
{ j8[RDiJ
  
nStartPos = input.readLong(); 4apy{W  
nEndPos = input.readLong(); Wm#F~
<$  
} 6-6ha7]s  
input.close(); X:kqX[\>  
} q37d:Hp  
catch(IOException e){e.printStackTrace ();} x<gP5c>zm  
catch(Exception e){e.printStackTrace ();} s-lNpOi  
} Xub<U>e;b  
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private void processErrorCode(int nErrorCode) D.:6X'hp  
{ aEvW<jHh  
System.err.println("Error Code : " + nErrorCode); kh5VuXpe  
} )/mBq#ZS  
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gi#g)9HG  
//停止文件下载 !Sj
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public void siteStop() W9M~2< L  
{ @q/E)M?  
bStop = true; "x~su?KiA  
for(int i=0;i<nStartPos.length;i++)
#[B]\HO  
fileSplitterFetch.splitterStop(); zg+6< .
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} T@P[jtH<d  
} 3-6Lbe9H  
//负责部分文件的抓取 XFmTr@\M  
**FileSplitterFetch.java 40$- ]i  
*/ vp2s)W8W  
package NetFox; ,SB5"  
=,w(D~ps  
bZf}m=C!  
import java.io.*; W^"C|4G}  
import java.net.*; 1wTPT,k  
u!@(u!Qz  
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public class FileSplitterFetch extends Thread { J)n^b  
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r  
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String sURL; //File URL t4[<N  
long nStartPos; //File Snippet Start Position NDYm7X*et  
long nEndPos; //File Snippet End Position \\iX9-aI<  
int nThreadID; //Thread's ID @0[#XA_>  
boolean bDownOver = false; //Downing is over 8H@]v@Z2  
boolean bStop = false; //Stop identical W"[Q=$2<<  
FileAccessI fileAccessI = null; //File Access interface I:=rwnd  
5!jU i9  
3Q:HzqG  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException O;8
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{ !HCuae3_  
this.sURL = sURL; 2uT"LW/(H  
this.nStartPos = nStart; 8D:0Vhx\I  
this.nEndPos = nEnd; D4
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nThreadID = id; oUNuM%g9Dy  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Dhze2q)o  
} Ra)AQ n  
_/[}PQC6G  
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public void run() z;Yo76P  
{ L{F[>^1Sb  
while(nStartPos < nEndPos && !bStop) E E^lw61  
{ DNu-
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try{ q.s'z}  
URL url = new URL(sURL); L&LAh&%{2  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); dBb &sA-A  
httpConnection.setRequestProperty("User-Agent","NetFox");  P0<)E  
String sProperty = "bytes="+nStartPos+"-"; H{U(Rt]
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httpConnection.setRequestProperty("RANGE",sProperty); 5[0W+W  
Utility.log(sProperty); ,?oC+9w  
./i5VBP5  
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InputStream input = httpConnection.getInputStream(); w0&|8y  
//logResponseHead(httpConnection); Y{D?
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!_  
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byte[] b = new byte[1024]; PFI^+';  
int nRead; &1Cif$Y4w  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop)  sDl@  
{ %pj T?G7  
nStartPos += fileAccessI.write(b,0,nRead); !$pnE:K  
//if(nThreadID == 1) 32z2c:G  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); B1 Y   
} 0u?VnN<  
)z!#8s  
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Utility.log("Thread " + nThreadID + " is over!"); /C6$B)w_*{  
bDownOver = true; 34:Y_*  
//nPos = fileAccessI.write (b,0,nRead); !t!'  
} d A>6  
catch(Exception e){e.printStackTrace ();} ',m!L@7M5  
} bR*} s/  
} RXw }Tb/D8  
&|I{ju_  
fM!@cph(8  
//打印回应的头信息 7Sl"q=>  
public void logResponseHead(HttpURLConnection con) K_GqM9  
{ FM,o&0HSd  
for(int i=1;;i++) AYsiaSTRqW  
{ u3C0!{v  
String header=con.getHeaderFieldKey(i); o-
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-  
if(header!=null) AB=Wj*fr  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ;MH_pE/m  
Utility.log(header+" : "+con.getHeaderField(header)); ZLlAK?N  
else @pN6uDD}R  
break; yW@YW_2;4  
} @S)p{T5G  
} zn#lFPj12  
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public void splitterStop()  Q5
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{ [PH56f  
bStop = true; \2[sUY<W  
} Pf#DBW*  
oD3Q{e  
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}
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/* 4P=)u}{]^#  
**FileAccess.java d~;U-  
*//文件访问(定位，写) 1EQLsg`d^  
package NetFox;
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import java.io.*; $g '4'  
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public class FileAccessI implements Serializable{ LX</xI08W  
kb[+II  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 =~q Xzq  
RandomAccessFile oSavedFile; C^ZDUj`  
long nPos; Y@MFH>*  
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3Gt@Fo=  
public FileAccessI() throws IOException <4Ik]Uz^  
{ O#`y;%  
this("",0); jBU!xCO  
} %B(E;t63W  
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public FileAccessI(String sName,long nPos) throws IOException Hh'o:j(^  
{ vPM2cc/o  
oSavedFile = new RandomAccessFile(sName,"rw"); kY#sQz}8  
this.nPos = nPos; <5npVm  
oSavedFile.seek(nPos); #Ti5G"C  
} Hr/Q?7g  
}0 =gP?.kE  
gsVm)mkd  
public synchronized int write(byte[] b,int nStart,int nLen)
[-h=L Jf#  
{ VL2ACv(  
int n = -1; UQ~gjnb[c  
try{ 3$PGLM  
oSavedFile.write(b,nStart,nLen); pXf5/u8&  
n = nLen; m`#UV-$J  
} "tz`@3,5dN  
catch(IOException e) w%eEj.MI|i  
{ iJzW3%E  
e.printStackTrace (); $}.#0c8I  
} ' eH Fa  
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return n; M9/J!s  
} YiC
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} M3YC@(N% k  
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/* p"QV| `  
**SiteInfoBean.java '/@i} digf  
*/ `W{y  
package NetFox; M~-jPY,+  

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public class SiteInfoBean { 5 0<  
!KLY*bt6  
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private String sSiteURL; //Site's URL ::!{f+Up  
private String sFilePath; //Saved File's Path &u0on)E  
private String sFileName; //Saved File's Name s3oQ( wC %  
private int nSplitter; //Count of Splited Downloading File Mf`@X[-;  
-_fh=}.n+"  
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public SiteInfoBean() ]t;bCD6*  
{//nSplitter的缺省值为5 Te@=8-u-  
//default value of nSplitter is 5 rNeSg=j  
this("","","",5); c'Zs2s7$  
} wsAijHjJI!  
9P#<T7
  
v v]rXJu1  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ~%u;lr  
{ p"o_0{8  
sSiteURL= sURL; ~4u[\&Sh  
sFilePath = sPath; 5+Hw @CY3  
sFileName = sName; z?Qt%1q  
this.nSplitter = nSpiltter; Schvwlm~i  
7=pJ)4;ZA  
kT4Oal+4  
} a'YK1QX  
|v= */
e  
YE1X*'4  
public String getSSiteURL() [+>cW0a  
{ uOQl;}Lk5  
return sSiteURL; A9ru]|?  
} %<;PEQQ|C  
_2nNCu (  
mY!&*nYn|  
public void setSSiteURL(String value) ,B$m8wlI|  
{ L=<{tzTc  
sSiteURL = value; ;p/$9b.0:  
} $qfNEAmDf\  
PVX23y;  

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public String getSFilePath() Gcd'-1  
{ 2JLXDkZ  
return sFilePath; nVv=smVOt  
} KmaMS(A(3  
_kJW/3eE  
5Jm%*Wb  
public void setSFilePath(String value) |9fGn@-  
{ nfA#d-  
sFilePath = value; KU)~p"0[6]  
} ^fT?(y_=e  
*N3X"2X:  
Xjnv8{
X  
public String getSFileName() _U`1BmTC2  
{ mNnt9F3Eq  
return sFileName; pXq5|,aC  
} ,|Lf6k  
7Un5Y[FZo  
`T~~yM)q  
public void setSFileName(String value) kc}&\y  
{ S$1dXXT  
sFileName = value; G|.5.FK^  
} Yp8GW1@  
Nk&$b  
aW7)}"j4  
public int getNSplitter() O`Ge|4  
{ KImazS^  
return nSplitter; zua
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} jY ~7-  
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%
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public void setNSplitter(int nCount) `=VN\W^&  
{ $C~OV@I  
nSplitter = nCount; x
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} 9ZXEy }q57  
} 3ew`e"s  
H?W8_XiN  
hF7#i_UN<  
/* 4/M~#  
**Utility.java 2N[S*#~*e  
*/ I,wgu:}P#  
package NetFox; <-K'9ut,  
DW.vu%j^[  
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public class Utility { LFT)_DG7(  
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public Utility() n0<I  
{ K!BS?n;  
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Gs)2HR@>  
} `]3A#y)v  
mQy!*0y  
//线程睡眠 Y> f 6  
public static void sleep(int nSecond) C6cEt5  
{ BaUcmF2Q  
try{ B|(MxR6m  
Thread.sleep(nSecond); cR"?EQ] `N  
} wSd o7Lb  
catch(Exception e) QocR)aN=+  
{ Qg' {RAV8  
e.printStackTrace (); 0N(o)WRv  
} =&xNdc  
} tf_<w?~  
J'no{3Ktz  
//日志 d-sK{ZC"y  
public static void log(String sMsg) T`gR&n<D  
{ XlHt(d0h
 
System.err.println(sMsg); 1T@#gE["Ic  
} o2#_CdU  
ilpP"B  
^ ;XJG9a0\  
public static void log(int sMsg) ?7"6dp_K  
{ =w <;tb  
System.err.println(sMsg); sGs_w:Hn  
} 7.N~e}p8  
} \OX;ZVb?5  
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/* TDo!yQ  
**TestMethod.java oUG!=.1}K5  
*/ K:\db'``  
package NetFox; (np60mX<  
9j
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eQQ*ZNG  
public class TestMethod { !HPye@Ua  
L5
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d2XSw>  
public TestMethod() ,U^V]
jC  
{ ///xx/weblogic60b2_win.exe 2J5RZg9jL  
try{ B8sc;Z.  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); B%Vz -t  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); N);2 2-  
SiteFileFetch fileFetch = new SiteFileFetch(bean); {,`)  
fileFetch.start(); [c_o.`S_\  
} d"Ae
r  
catch(Exception e){e.printStackTrace ();} @+
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} 5h6c W  
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public static void main(String[] args)  a8wQ,  
{ e qzmEg  
new TestMethod(); OX!<{9o  
} vv% o+r-t  
} c^ifHCt|  
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