http断点续传简单实现（java)

/* } oJ+2OepN  
**SiteFileFetch.java +SM $#  
*/ MxxYMR  
package NetFox; r&"}zyL  
import java.io.*; <
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import java.net.*; wd*i~A3+?  
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public class SiteFileFetch extends Thread { ) 0$7{3  
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SiteInfoBean siteInfoBean = null; //文件信息Bean j._9;HifZ  
long[] nStartPos; //开始位置 ltt%X].[  
long[] nEndPos; //结束位置 V~5vVY_HG&  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ))!Z2PfD  
long nFileLength; //文件长度 %Ua*}C   
boolean bFirst = true; //是否第一次取文件 D`e!CprF  
boolean bStop = false; //停止标志 Kv+E"2d  
File tmpFile; //文件下载的临时信息 Z!6\KV]  
DataOutputStream output; //输出到文件的输出流 }"fP,:n"KN  
8_f0P8R!y  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） mT@UQCG  
public SiteFileFetch(SiteInfoBean bean) throws IOException pw:<a2.  
{ yyk[oH-Q  
siteInfoBean = bean; (|ga#%iI  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ^`YSl*:  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); }K;@$B6,@  
if(tmpFile.exists ()) F=B>0Q5  
{ ]*}*zXN/E  
bFirst = false; Opmb   
read_nPos(); jL8&  
} )aquf<u@  
else u4$d#0sA  
{ dT,X8 "  
nStartPos = new long[bean.getNSplitter()]; i[d-n/)  
nEndPos = new long[bean.getNSplitter()]; *we3i  
} =0,")aa!  
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\ ;Hj,z\  
} >?M:oUVDU  

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public void run() *~4uF  
{ F.?:Gd1  
//获得文件长度 x:;8U i"&B  
//分割文件 UOF5&>MLb  
//实例FileSplitterFetch Pc? d@tm  
//启动FileSplitterFetch线程 |Uy hH^  
//等待子线程返回 (5-"5<-@R  
try{ `;*=2M<c  
if(bFirst) XnWr~h{b  
{ ]9zc[_ !  
nFileLength = getFileSize(); a>sUq["  
if(nFileLength == -1) `Lm ArW:  
{ B_`A[0H  
System.err.println("File Length is not known!"); 4OCz:t  
} LLgN%!&  
else if(nFileLength == -2) ,0<|&D  
{ @z dmB~C  
System.err.println("File is not access!"); z2!NBOv  
} 
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else &[S)zR=?  
{
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for(int i=0;i<nStartPos.length;i++) nImRU.;P  
{  +aP%H  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); "5XD+qi  
} \C}tK,79  
for(int i=0;i<nEndPos.length-1;i++) :+]6SC0ql  
{
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nEndPos = nStartPos[i+1]; a<!g*UVL0M  
} %~Nf,  
nEndPos[nEndPos.length-1] = nFileLength; IIop"6Ko  
} o,bV.O.W  
} X@x: F|/P  
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4,H}'@Db}  
//启动子线程 FjiLc=RXXz  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; }}t"^ms  
for(int i=0;i<nStartPos.length;i++) HW.S~eLw*  
{ qK|r+}g|&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), A!iH g__/t  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), gADt%K2#Z  
nStartPos,nEndPos,i); $6fHY\i#R  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); \jq1F9,  
fileSplitterFetch.start(); *I'O_D  
} .vQ2w  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Yz-b~D/=}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); (jY.S|%  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", HaB=nLAT  
nEndPos = " + nFileLength); Kh<v2  
// fileSplitterFetch[nPos.length-1].start(); Duptles  
vU{ZB^+&6o  
2Y 6/,W  
//等待子线程结束 ^Po\:x%o  
//int count = 0; k qwS/s  
//是否结束while循环 Ta/G  
boolean breakWhile = false; ( Y/ DMQ  

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while(!bStop) ~&B_ Bswf  
{ j nI)n*  
write_nPos(); rQisk8%  
Utility.sleep(500); '|Q=J)  
breakWhile = true; dUjdQ  
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for(int i=0;i<nStartPos.length;i++) 1grrb&K  
{ =N7N=xY  
if(!fileSplitterFetch.bDownOver) f+<-Jc  
{ 1RRvNZW  
breakWhile = false; [>"qOFCr#:  
break; wy) Frg  
} %HYC-TF#  
} m} Yf6:cr  
if(breakWhile) u{6*}6@fi  
break; 3kYUO-qw  
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//count++; )%ja6
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//if(count>4) qY14LdC}~  
// siteStop(); {R1jysGtD  
} $ P#k|A
 
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System.err.println("文件下载结束！"); *vBcT.|,  
} zI7-xqZ  
catch(Exception e){e.printStackTrace ();} 1/l
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} M
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,dh*GJ{5  
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//获得文件长度 :O//A6v  
public long getFileSize() s/,St!A4!  
{ 2d$hgR#v  
int nFileLength = -1;  ZfvFs  
try{ uE5kL{Fv  
URL url = new URL(siteInfoBean.getSSiteURL()); aYPzN<"%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); EWqKd/  
httpConnection.setRequestProperty("User-Agent","NetFox"); hrcR"OZ~X  
?c>j^}A/N  
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int responseCode=httpConnection.getResponseCode(); l'3NiIX  
if(responseCode>=400) 2@e<II2ha8  
{ (5G^"Srw  
processErrorCode(responseCode); %f{
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return -2; //-2 represent access is error +;cw<9%0  
} Yj0Ss{Ep  

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String sHeader; vRT1tOQ$  
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for(int i=1;;i++) =BX<;vU  
{ '{OZ[$E  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); {mkYW
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//Utility.log(in.readLine()); kTC6fNj[  
sHeader=httpConnection.getHeaderFieldKey(i); SrHRpxy  
if(sHeader!=null) 7Bmt^J5i&t  
{ >mt<`s  
if(sHeader.equals("Content-Length")) eU{=x$o6S  
{ KtV_DjH:  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 3s>&h-E  
break; ^'
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} TSuHY0.cp  
} Q*KEODR8\  
else >nl*aN  
break; !vett4C* K  
} -{L[Wt{1  
} \>I&UFfH)4  
catch(IOException e){e.printStackTrace ();} TR:D  
catch(Exception e){e.printStackTrace ();}  "&C'K  
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Utility.log(nFileLength); :5"|iRP'  
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return nFileLength; #j;&g1  
} wF38c]r`\<  
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//保存下载信息（文件指针位置） /{qr~7k,oQ  
private void write_nPos() {}lw%d?A  
{ YTYYb#"Q  
try{ "=/XIM.  
output = new DataOutputStream(new FileOutputStream(tmpFile)); '-ACNgNn  
output.writeInt(nStartPos.length); (mza&WF7  
for(int i=0;i<nStartPos.length;i++) J-I7K!B  
{ y4envjl0  
// output.writeLong(nPos); ~'T]B{.+J  
output.writeLong(fileSplitterFetch.nStartPos); C(?lp  
output.writeLong(fileSplitterFetch.nEndPos); b/S4b  
} ^M?uv
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output.close(); KN+*_L-  
}
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catch(IOException e){e.printStackTrace ();} }-8K*A3  
catch(Exception e){e.printStackTrace ();} e1+ %c9UQ  
} Q7#Q6-Q  
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//读取保存的下载信息（文件指针位置） \8F$85g  
private void read_nPos() _G'.VSGH  
{ ]`:Fj|>  
try{ O`Z>Oon?  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Gm.v-T$  
int nCount = input.readInt(); ]CHMkuP[k  
nStartPos = new long[nCount]; #Q|$&b  
nEndPos = new long[nCount]; !5=3Y4bg1  
for(int i=0;i<nStartPos.length;i++) %oN^1a'&)  
{ {OQ sGyR?  
nStartPos = input.readLong(); q .?D{[2  
nEndPos = input.readLong(); 7 H<_ wW  
} cJH7zumM)  
input.close(); (cA=~Bw[=  
} S liF$}J  
catch(IOException e){e.printStackTrace ();} VDQ&BmJE  
catch(Exception e){e.printStackTrace ();} LU%g>?m.]  
} `D GO~RMp9  
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private void processErrorCode(int nErrorCode) 1uD}V7_y"  
{ 6|9];)  
System.err.println("Error Code : " + nErrorCode); iOD9lR`s  
} )fCl<KG*  
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//停止文件下载 &=s{ +0  
public void siteStop() r%xNfTa  
{ TmUn/  
bStop = true; s]=kD  
for(int i=0;i<nStartPos.length;i++) r9u
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fileSplitterFetch.splitterStop(); Zl* HT%-5  
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} U;{VL!  
} $x`U)pv  
//负责部分文件的抓取 XvdK;  
**FileSplitterFetch.java \W$
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*/ qP]Gl--q{  
package NetFox; ozGK
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import java.io.*; OO\UF6MCU  
import java.net.*; 6%fU}si,  
4#=^YuKaF1  
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public class FileSplitterFetch extends Thread { [c3hwogf:  
SUvHLOA  
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String sURL; //File URL EcP"GO5  
long nStartPos; //File Snippet Start Position 4\-kzGgmo  
long nEndPos; //File Snippet End Position `%rqQnVB  
int nThreadID; //Thread's ID a:P% r  
boolean bDownOver = false; //Downing is over vbA9V<c&  
boolean bStop = false; //Stop identical Be}Cj(C  
FileAccessI fileAccessI = null; //File Access interface v'Lckw@G4  
_<5> E  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException g:OVAA  
{ xx41Qw>\W  
this.sURL = sURL; beO*|  
this.nStartPos = nStart; hQX|wWh  
this.nEndPos = nEnd; /~AajLxu3W  
nThreadID = id; OZ7MpQ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 U[Z1@2zLx  
} #<l;YT8  
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public void run() }.e*=/"MB  
{ ^>]p4Q3 6  
while(nStartPos < nEndPos && !bStop) bD49$N?>  
{ F1MPo;e  
,!Ah+x  
?K}/b[[0v  
try{ f$/Daq <M  
URL url = new URL(sURL);
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); F5EKWP  
httpConnection.setRequestProperty("User-Agent","NetFox"); b/2t@VlL  
String sProperty = "bytes="+nStartPos+"-"; 6IeHZ)jGj  
httpConnection.setRequestProperty("RANGE",sProperty); ~Uga=&  
Utility.log(sProperty); vbh\uv&  
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InputStream input = httpConnection.getInputStream(); u QCQ$  
//logResponseHead(httpConnection); ;:'A{&0N  
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byte[] b = new byte[1024]; 9I.="b=J)  
int nRead; {OB\~$TH  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 6B|IbQ^  
{ wn|Sdp  
nStartPos += fileAccessI.write(b,0,nRead); , gz:2UY#  
//if(nThreadID == 1) =Ermh7,  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); uv._N6mj  
} ][#]4_  
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Utility.log("Thread " + nThreadID + " is over!"); O(wt[AE
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bDownOver = true; E[e ''  
//nPos = fileAccessI.write (b,0,nRead); .!=2#<  
} wVw3YIN#  
catch(Exception e){e.printStackTrace ();} _`ot||J  
} ?l bK;Kv  
} o- GHAQ  
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//打印回应的头信息
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public void logResponseHead(HttpURLConnection con) s{hJ"lv:  
{ Z wIsEJz  
for(int i=1;;i++) 6XB9]it6  
{ "EHwv2Hm>  
String header=con.getHeaderFieldKey(i); oXb}6YC  
if(header!=null) [%YCupr#  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); o^5xCK:Oi2  
Utility.log(header+" : "+con.getHeaderField(header)); iQs(Dh=*  
else 72luTR Q  
break; WEWNFTI  
} )I`B+c:  
} CA:t](xqQ  
@K2q*d  
#@lLx?U  
public void splitterStop() # l}Y1^PDd  
{ Y+j|T`d  
bStop = true; QnVYZUgJeV  
} \vojF\  
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} -:>Mi5/ s  
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/* dN;C-XF3s  
**FileAccess.java 1;g>?18@  
*//文件访问(定位，写) BWz*!(   
package NetFox; -bcm"(<T'  
import java.io.*; >*k3D&  
yv]/A<gP+  
zTm&m#){3A  
public class FileAccessI implements Serializable{ 53@*GXzE  
|*jnJWH4:  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ~b\bpu  
RandomAccessFile oSavedFile; 3S +.]v>  
long nPos; 7n}J}8Y*U2  
M|7xI  
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public FileAccessI() throws IOException '+5*ajP<  
{ 3Sf<oYF  
this("",0);
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} Kcl>uAgU  
^JJ*pT:  
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public FileAccessI(String sName,long nPos) throws IOException c$bb0J%  
{ 45q-x_  
oSavedFile = new RandomAccessFile(sName,"rw"); fPa FL}&  
this.nPos = nPos; Q4}2-}|  
oSavedFile.seek(nPos); :anUr<  
} Z^>{bW  
=P-kb^s  
)lBke*j~  
public synchronized int write(byte[] b,int nStart,int nLen) cZPv6c_w  
{ DXsp 2
  
int n = -1; 349W0>eOT  
try{ k7'B5zVd  
oSavedFile.write(b,nStart,nLen); 2LEf"FH0~  
n = nLen; [N'YFb3"O  
} M')f,5i&$  
catch(IOException e) rp{q.fy'U  
{ K!0vvP2H  
e.printStackTrace (); DO8@/W( `  
} QI.{M$,m~  
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9)];l?l  
return n; +MvcW.W~  
} Qis[j-?:  
u @?n3l  
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} LlrUJ-uC7  
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/* z~# .Ey  
**SiteInfoBean.java _2R;@[f2  
*/ ~jQ|X?tR  
package NetFox; 7%b?[}y4  
mr,IP=e~  
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public class SiteInfoBean { /YKg.DA|  
[daUtKz  
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private String sSiteURL; //Site's URL ,73J#  
private String sFilePath; //Saved File's Path pIXbr($  
private String sFileName; //Saved File's Name &$
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private int nSplitter; //Count of Splited Downloading File jO&sS?  
)Gi!wm>zvN  
2g$PEwXe  
public SiteInfoBean() >;-.rJFr
 
{//nSplitter的缺省值为5 x_GD  
//default value of nSplitter is 5 A9`& Wnw?  
this("","","",5); 2"cUBFc1I  
} @!1o +x  
PJ5~,4H-4  
vR[XbsNM  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 'avzESe~'  
{ [AstD9  
sSiteURL= sURL; =aX;-
 
sFilePath = sPath; \fj*.[,  
sFileName = sName; ANR?An  
this.nSplitter = nSpiltter; |08b=aR6ro  
1MkQ$v7m  
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} df
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Ha>Hb`  
public String getSSiteURL() j*B,b4  
{ gY9HEfB  
return sSiteURL; &FHzd/  
} 8b\XC%k  
dT?/9JIv  
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public void setSSiteURL(String value) c5Fl:=h  
{ >NwS0j$j@  
sSiteURL = value; 
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} 1U[Q)(P  
<H03i"Z/S  
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public String getSFilePath() jrJ!A(<)  
{ u*u3<YQ  
return sFilePath; 6AD#x7drj  
} X` r~cc  
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1-Jd
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public void setSFilePath(String value) L+VqTt  
{ vo<'7,  
sFilePath = value; G(joamfM  
} O1]L4V1iH  
1X.E:  
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public String getSFileName() P`^3-X/  
{ T)4pLN E  
return sFileName; CNP!v\D  
} [[ {L#  
t,H=;U#  
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public void setSFileName(String value) G)5R iRcs  
{ sKDsps^$  
sFileName = value; LkvR]^u0  
} uknX py))  
&gGh%:`B  
0G?*i_u\  
public int getNSplitter() +h*-9  
{ 55LW[Pc  
return nSplitter; @s7ZfV??  
} rx[l7F q  
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wN}@%D-[v  
public void setNSplitter(int nCount) !g|)?XWc  
{ }[2  
nSplitter = nCount; %# M=qP  
} f)'mpp^  
} %BBM%Lj  
}KFf  
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/* *n]f)Jc  
**Utility.java #POVu|Y;h  
*/ :[P)t %  
package NetFox; 4gKu8G  
#
^FDG1=  
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public class Utility { {"e)Jj_=  
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GQ-fEIi{  
public Utility() ]]"O)tWHj  
{ ^qR2!fwm<  
;-]' OiS;  
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} -2DvKW$  
9Su4nt`i  
//线程睡眠 cpLlkR O  
public static void sleep(int nSecond) JJE?!Yvc  
{ <A~a|A-QFR  
try{ r3OR7
f[  
Thread.sleep(nSecond); vIzREu|5  
} `PoFKtVXM  
catch(Exception e) Gn?NY}.S  
{ rm}%C(C{J  
e.printStackTrace (); Fi!BXngbd  
} ue8"_N  
} -w'_Q"o2  
ctk~}(1#  
//日志 Sj(5xa[  
public static void log(String sMsg) ]0dj##5tJ  
{ ]wxjd l  
System.err.println(sMsg); _ZMAlC*$G  
} >(.GIR  
AX{X:L8Ut2  
GBg~NkC7.  
public static void log(int sMsg) f$y`tT %o  
{ 70Z#Ej  
System.err.println(sMsg); /BN_K8nb`  
} fex<9'e  
} > a?K![R  
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@'AjEl:&-_  
/* _-+xzdGvX  
**TestMethod.java j:>_1P/  
*/ 9'" F7>d  
package NetFox; K`vc&uf  
d94Le/E  
xCTPsw]s  
public class TestMethod { :MPfCiAv  
/}kG$~  
qdCcMcGt  
public TestMethod() y3+iADo.p  
{ ///xx/weblogic60b2_win.exe L^E#"f  
try{ QKB*N)%6  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); cfZ$V^xM  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); E:$EK_?:t  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Y W9+.Dc`  
fileFetch.start(); zBjtPtiiI8  
} 7{JIHY+  
catch(Exception e){e.printStackTrace ();} `m")v0n3  
UURYK~$K:  
`qs[a}%'>"  
} oE.59dx  
a #`Y(R'  
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public static void main(String[] args) ?h|&kRq  
{ 6k9cvMs%H  
new TestMethod(); g15~+;33N  
} YQ-!>3/)-  
} )W,.xP  
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