http断点续传简单实现（java)

/* pim!.=vN/U  
**SiteFileFetch.java R.yC(r  
*/ \Rp-;.I@6  
package NetFox; *cgI.+  
import java.io.*; ?W)A  
import java.net.*; vMm1Z5S/  
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public class SiteFileFetch extends Thread { v+X)Qmzf~  
6#HK'7ClL  
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SiteInfoBean siteInfoBean = null; //文件信息Bean {o>j6RS\  
long[] nStartPos; //开始位置 nYX@J6!  
long[] nEndPos; //结束位置 -&-Ma,M?  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 N9v1[~ bv_  
long nFileLength; //文件长度 SF>c\eTtx  
boolean bFirst = true; //是否第一次取文件 c5u@pvSP  
boolean bStop = false; //停止标志 i~{Ufi  
File tmpFile; //文件下载的临时信息 ekWePL;rR2  
DataOutputStream output; //输出到文件的输出流 f>N!wgo[  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） #N`~xZ|$  
public SiteFileFetch(SiteInfoBean bean) throws IOException *exS6@N]  
{ e8GEoD  
siteInfoBean = bean; <kx&w(=  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); * iF]n2g:  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); !y@6Mm  
if(tmpFile.exists ()) CW,Wx:Y  
{ l\@)y4 +  
bFirst = false; ::
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read_nPos(); ;JayoJ  
} FgB&b  
else [m|YWT=  
{ ~4 `5tb  
nStartPos = new long[bean.getNSplitter()]; Np"exFqN k  
nEndPos = new long[bean.getNSplitter()]; j
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} 70eb]\%  
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} lx[oaCr  
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public void run() _Nqt21sL  
{ /,g,Ch<d  
//获得文件长度 r(RKwr:m  
//分割文件 pLLGus+W  
//实例FileSplitterFetch Bi @2  
//启动FileSplitterFetch线程 %>g3~yl  
//等待子线程返回 $7rq3y  
try{ f
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if(bFirst) *U P@9D  
{ -i%e!DgH  
nFileLength = getFileSize(); _N{RVeO  
if(nFileLength == -1) :{q<{^c  
{ u[DfzH  
System.err.println("File Length is not known!"); N-e @j4WU  
} [<  &oF  
else if(nFileLength == -2) \uaJ@{Vug  
{ yrC7F`.  
System.err.println("File is not access!"); IrqZi1  
} ):b$xNn  
else TX&Jt%  
{ x7eQ2h6O  
for(int i=0;i<nStartPos.length;i++) c'S,hCe*  
{ Q|D @Yd\  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); IVAmV!.z  
} .O0+H+  
for(int i=0;i<nEndPos.length-1;i++) pQtJc*[!  
{ wfq7ob4^  
nEndPos = nStartPos[i+1]; G}ob<`o|"  
} H\0~#(z?.  
nEndPos[nEndPos.length-1] = nFileLength; f7X6fr<  
} E:
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}
,#L=v]  
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//启动子线程 J 
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 0a-0Y&lQm  
for(int i=0;i<nStartPos.length;i++)  y"H*%]  
{ \uza=e  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), t3&LO~Ye  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), *fn*h[pV&  
nStartPos,nEndPos,i); Ljx(\Cm  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); d ysC4DS  
fileSplitterFetch.start(); 'U\<IL#U  
} [Z}9>~m  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $D|e>U  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); T<55a6NoK  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 4DL)rkO  
nEndPos = " + nFileLength); Cc%LztP>  
// fileSplitterFetch[nPos.length-1].start(); woD>!r>)  
j ~1B|,H  
*rIk:FehLB  
//等待子线程结束 ;3B1_vo9  
//int count = 0; Cif>7]M  
//是否结束while循环 Ns7(j-  
boolean breakWhile = false; o'f?YZ$.  
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while(!bStop) LRb{hUt=  
{ /qy-qUh3h  
write_nPos(); @EnuJe  
Utility.sleep(500); n=c 2Kc  
breakWhile = true; P#XID 2;  
5`gQ~  
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for(int i=0;i<nStartPos.length;i++) 1>E<8&2[L  
{ ZRg;/sX]  
if(!fileSplitterFetch.bDownOver) RkBb$q9F]  
{ V9dF1Hj  
breakWhile = false; R)RG[F#  
break; PE
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} 7,lq}a8z  
} ^ml'?  
if(breakWhile) #7q7PYG4  
break; 2gq9k}38  
j
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@++.F
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//count++; }A7j/uy}s  
//if(count>4) iTAx
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// siteStop(); Htgx`N|  
} 2VE9}%i  
/5:bvg+  
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System.err.println("文件下载结束！"); }7 c[Q($K  
} \V*xWS  
catch(Exception e){e.printStackTrace ();} b+&%1C  
} |qmu_x\  
A#95&kJpy  
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//获得文件长度 X  .5aMm  
public long getFileSize() fvF?{k>~}  
{ w6W}"Uw  
int nFileLength = -1; Gq }U|Z  
try{ =aoMii   
URL url = new URL(siteInfoBean.getSSiteURL()); viMzR(JU  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); HFaj-~b  
httpConnection.setRequestProperty("User-Agent","NetFox"); "huFA|`  

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5&q8g;XiEM  
int responseCode=httpConnection.getResponseCode(); vDxe/x%  
if(responseCode>=400) B9H@e#[  
{ 8'4S8DM  
processErrorCode(responseCode); "t_-f7fS7  
return -2; //-2 represent access is error R]btAu;Z  
} U2wbvXr5-  
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String sHeader; s8#X3Rp  
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@p NNq
  
for(int i=1;;i++) X7i/fm
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{ kT!9`S\  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); pFHz"]  
//Utility.log(in.readLine()); 9uBM<  
sHeader=httpConnection.getHeaderFieldKey(i); ~(IB0=A{v  
if(sHeader!=null) t{WzKy  
{ 
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if(sHeader.equals("Content-Length")) iIq)~e/ Z  
{ vc+ARgvH+  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 8qEVOZjV&  
break; Ts ^"xlK  
} P}TI q#  
} \u>"s   
else :E@3Vl#U  
break; cvfr)K[0  
} %ve:hym*  
} :
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catch(IOException e){e.printStackTrace ();} |Clut~G  
catch(Exception e){e.printStackTrace ();} 'Ub g0"F(  
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Utility.log(nFileLength); D0#x Lh  
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return nFileLength; 846$x$G4  
} y?a Acn$  
z3K6%rb-  
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//保存下载信息（文件指针位置） r;Gi+Ca5  
private void write_nPos() 7qg{v9|,  
{ ]jaQ[g$F  
try{ P3nb2.  
output = new DataOutputStream(new FileOutputStream(tmpFile)); N.]qU d  
output.writeInt(nStartPos.length); 8qu2iPOcZ  
for(int i=0;i<nStartPos.length;i++) }=6'MjF]  
{ IS#FiH  
// output.writeLong(nPos); zOqn<Y@  
output.writeLong(fileSplitterFetch.nStartPos); !>e5z|1   
output.writeLong(fileSplitterFetch.nEndPos); }c`fW&  
} _;~,Cgfi  
output.close(); I]&#Dl/  
} F;l$.9?.s  
catch(IOException e){e.printStackTrace ();} ,XIz?R>;c  
catch(Exception e){e.printStackTrace ();} xgNJeQ  
} K,boVFs  
|&[L?  
8&3V#sn'  
//读取保存的下载信息（文件指针位置） '&gF>  
private void read_nPos() #z2rzM@/:  
{ 4)"n RjGg  
try{ }f8Uc+  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); u#V5?i  
int nCount = input.readInt(); K!'AkTW+-  
nStartPos = new long[nCount]; C0 /g1;p(  
nEndPos = new long[nCount]; Z6_N$Z.A  
for(int i=0;i<nStartPos.length;i++) 3&[>u;Bp  
{ DiEluA&w9  
nStartPos = input.readLong(); M5*{  
nEndPos = input.readLong(); I{lT>go  
} 7A\~)U@  
input.close(); #L{OV)a<  
} 3'c0#h@VD  
catch(IOException e){e.printStackTrace ();} GA?87N  
catch(Exception e){e.printStackTrace ();} H*Kj3NgY  
} D!.+Y-+Xzu  
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private void processErrorCode(int nErrorCode) @:U+9[  
{ YE=q:Bv  
System.err.println("Error Code : " + nErrorCode); @W^| ?  
} P '>SmQ  
}p!HT6 tZ  
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//停止文件下载 FFH_d <q  
public void siteStop() NDs!a  
{ mXUGe:e8  
bStop = true; q@@T]V6  
for(int i=0;i<nStartPos.length;i++) &/uu)v  
fileSplitterFetch.splitterStop(); &%s8L\?  
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} \L(*]:EP  
} n< ud> JIb  
//负责部分文件的抓取 <HJl2p N  
**FileSplitterFetch.java @*qz(h]\  
*/ C":o/;,1  
package NetFox; n[]tXrhU  
) :\xHR4  
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import java.io.*; )@L'wW  
import java.net.*; Wt=|  
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public class FileSplitterFetch extends Thread { @~#Ym1{W  
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String sURL; //File URL .9"Y_/0   
long nStartPos; //File Snippet Start Position Ty<L8+B|  
long nEndPos; //File Snippet End Position
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int nThreadID; //Thread's ID K)-m*#H&uw  
boolean bDownOver = false; //Downing is over @EDs~ lPv  
boolean bStop = false; //Stop identical Nof3F/2 N&  
FileAccessI fileAccessI = null; //File Access interface KGWyJ  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException g=]u^&  
{  k0  
this.sURL = sURL; .>mr%#p  
this.nStartPos = nStart; sp ]zbX?  
this.nEndPos = nEnd; .{=$!8|&I9  
nThreadID = id; [<{Kw=X__2  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 x)JOClLr  
} \N4 y<  
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public void run() GN0`rEh  
{ gCN$}  
while(nStartPos < nEndPos && !bStop) Ai/b\:V9S  
{ wo3wtx  
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try{ y8 KX<2s1  
URL url = new URL(sURL); r} P<iX
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); c1_5, 1U'  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;]w<&C!=  
String sProperty = "bytes="+nStartPos+"-"; ]a!xUg!S  
httpConnection.setRequestProperty("RANGE",sProperty); 1|?05<8  
Utility.log(sProperty); ! /NG.Wf  
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InputStream input = httpConnection.getInputStream(); :T._ba3|  
//logResponseHead(httpConnection); v\,N5  
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byte[] b = new byte[1024]; k~/>b~.c  
int nRead; RiTa \  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) }->.k/vc  
{ A)
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nStartPos += fileAccessI.write(b,0,nRead); #_|sgS?1  
//if(nThreadID == 1) K3' niGT  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); p?2Y }9  
} 2<][%> '  
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Utility.log("Thread " + nThreadID + " is over!"); fsEzpUY:{W  
bDownOver = true;
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//nPos = fileAccessI.write (b,0,nRead);
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} Sje wuIi1  
catch(Exception e){e.printStackTrace ();} 3 AHY|  
} |hO~X~P  
} c(/VYMJZ&  
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//打印回应的头信息 &tZG @  
public void logResponseHead(HttpURLConnection con) [Cb`{  
{ NziZTU}
 
for(int i=1;;i++) .iQT5c  
{ -\y-qHgb/  
String header=con.getHeaderFieldKey(i); 'Vr
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if(header!=null) o d7]tOK9  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); xESjM1A)  
Utility.log(header+" : "+con.getHeaderField(header)); _6k*'aT~FK  
else $%%os6y2v  
break; +e-,ST&w(  
} e|rg;`AW  
} g!`3{ /4  
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public void splitterStop() bO;(bE m@  
{ yg2uC(2  
bStop = true; "GQl~  
} WnHUE  
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} `s]4AKBO  
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/* 9~0^PzTA  
**FileAccess.java teW6;O_  
*//文件访问(定位，写) )%X;^(zKM  
package NetFox; #$1og=  
import java.io.*; kip`Myw+  
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public class FileAccessI implements Serializable{ 7JDN{!jT  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ;oNhEB:F  
RandomAccessFile oSavedFile; gUR]{dq^'  
long nPos; 3^StIw{X  
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public FileAccessI() throws IOException 1 Vy,&[c~"  
{ &5%dhc4&!&  
this("",0); cDrebU  
} 2T)sXBu  
/_\#zC[  
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public FileAccessI(String sName,long nPos) throws IOException L!'k !k  
{ A;J MV+2N  
oSavedFile = new RandomAccessFile(sName,"rw"); &W6^6=E{g  
this.nPos = nPos; k{AyD`'Q  
oSavedFile.seek(nPos); mF09U(ci  
} a{!r`>I\f  
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public synchronized int write(byte[] b,int nStart,int nLen) ` r']^ ,  
{ oA tsUF+a  
int n = -1; b}G24{  
try{ 3I|3wQ&#(  
oSavedFile.write(b,nStart,nLen); }sxn72,  
n = nLen; )ZejQ}$  
} ;U`X 6d  
catch(IOException e) >~\w+^2f8  
{ _}mK!_`  
e.printStackTrace (); jAND7&W  
} t=R6mjb  
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return n; p
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} tVqmn  
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} 6<5Jq\-h  
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/* 3,);0@I  
**SiteInfoBean.java 7W9~1 .SC  
*/ IC{F.2D  
package NetFox; Gy@7Xf  
m=b~i^@  
gor<g))\  
public class SiteInfoBean { }'=h4yI  
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private String sSiteURL; //Site's URL NNa1EXZ[  
private String sFilePath; //Saved File's Path 2N~E' 25  
private String sFileName; //Saved File's Name z}.
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private int nSplitter; //Count of Splited Downloading File cX At:m  
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public SiteInfoBean() L|^o71t|  
{//nSplitter的缺省值为5 P`'$  
//default value of nSplitter is 5 OK`Z@X_,bW  
this("","","",5); D22Lu;E  
} fw{,bJ(U  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) t#<KxwhcN  
{ hN(L@0)  
sSiteURL= sURL; Z,WW]Y,$  
sFilePath = sPath; 3D)b*fPc  
sFileName = sName; .dI)R40L/\  
this.nSplitter = nSpiltter; g-yi xU  
}.:d#]g8  
}#=Od e  
} [.q(h/b  
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public String getSSiteURL() >Wh3MG6  
{ y67uH4&Vm  
return sSiteURL; PaVO"y]C  
} b4 hIeBI\  
9.0WKcwg  
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public void setSSiteURL(String value) 4R+P  
{ @+^c"=d1S  
sSiteURL = value; Lm.`+W5  
} x.EgTvA&d  
h)E|?b_  
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public String getSFilePath() 67J*&5? |  
{ W3LP ~  
return sFilePath; D{AFL.r{  
} 4YJ=q% G  
jNy?[ )  
/#yA%0=w  
public void setSFilePath(String value) Q[s2}Z!N;  
{ +$(0w35V5  
sFilePath = value; h39e)%x1  
} =w<VT%  
">6&+^BN'  
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public String getSFileName() )&.!3y 660  
{ j 0 Y  
return sFileName; +AK:
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} /R%^r
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public void setSFileName(String value) #'>?:k  
{ +8UdvMN  
sFileName = value; pN$;!  
} \$;~74}  
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public int getNSplitter() ek[kq[U9  
{ +5*vABvCu  
return nSplitter; 9bEM#Hj  
} VD#!ztcY'  
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public void setNSplitter(int nCount) O3ZM
:,.  
{ Za!w#j%h  
nSplitter = nCount; CT}' ")Bm  
} l^,qO3ES  
} aRKv+{K  
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/* 6_U|(f  
**Utility.java n{=7 yK  
*/ 2 `5=0E1k  
package NetFox; G{A)H_o*  
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public class Utility { NQ!<f\m4n  
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public Utility() ou;qO 5CT  
{ 6z1\a  
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} 0IFlEe[>#  
sJ7sjrEp1  
//线程睡眠 BVAr&cu  
public static void sleep(int nSecond) RH=$h! 5  
{ O3+)qb!X  
try{ Bj&_IDs4  
Thread.sleep(nSecond); ru(J5+H  
} (H[  
catch(Exception e) Q)+Y}  
{ \[k%)_  
e.printStackTrace (); l% |cB93  
} (+x]#
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} \=8=wQv  
#gI&lO*\gr  
//日志 <Cr8V'c  
public static void log(String sMsg) 3q CHh  
{ wDZ
  
System.err.println(sMsg); ~B*~'I9b*  
} *N'hA5.z  
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'g]=.K+@}  
public static void log(int sMsg) Q,n4i@E  
{ :K;T Q  
System.err.println(sMsg); zS?n>ElI  
} @%H8"A  
} 5&G 5eA  
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0T1ko,C!,e  
/* *) } :l  
**TestMethod.java '&)D>@g  
*/ QnP{$rT  
package NetFox; I)rGOda{  
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55,=[  
public class TestMethod { 2x6<8J8v*  
 Lxz  
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public TestMethod() 7y;u} 1  
{ ///xx/weblogic60b2_win.exe  yIa[yJq  
try{ nIR*_<ow  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); +h|K[=l\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); + lP5XY{  
SiteFileFetch fileFetch = new SiteFileFetch(bean);  *0-v!\{  
fileFetch.start(); [5!'ykZ  
} Kny%QB
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catch(Exception e){e.printStackTrace ();} T|!D>l'  
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} .`mtA`
N  
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public static void main(String[] args) >j) w\i  
{ ;{]8>`im&4  
new TestMethod(); joY1(Y  
} %P(;8sS  
} K
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