http断点续传简单实现（java)

/* I)-u)P?2x  
**SiteFileFetch.java h)M9Oup`  
*/ UJ0Dy` f  
package NetFox; Qbc62qFu!  
import java.io.*; L
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import java.net.*; EmDA\9~@R  
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public class SiteFileFetch extends Thread { D4"](RXH  
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SiteInfoBean siteInfoBean = null; //文件信息Bean W biUz2)  
long[] nStartPos; //开始位置 LRhq%7p7  
long[] nEndPos; //结束位置 ]Mh7;&<6[  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 GQ-owH]  
long nFileLength; //文件长度 #0-!P+c[  
boolean bFirst = true; //是否第一次取文件 JuGQS24  
boolean bStop = false; //停止标志 }G8RJxy  
File tmpFile; //文件下载的临时信息 c-INVA)  
DataOutputStream output; //输出到文件的输出流 t;DZ^Z"{  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Q7y6</4f  
public SiteFileFetch(SiteInfoBean bean) throws IOException -S=Zsr\  
{ 1%L* 9>e  
siteInfoBean = bean; 6,Q{/  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); %Km_Sy[7']  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); lPS
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if(tmpFile.exists ()) t9&z|?Vz  
{ E(T6s^8  
bFirst = false;
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read_nPos(); ,i2%FW  
} ?l_>rSly5  
else mu1oD;lQ  
{ b'$j* N  
nStartPos = new long[bean.getNSplitter()]; ;8~`fK  
nEndPos = new long[bean.getNSplitter()]; XR^VRn6O  
} A a2*f[  
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} P,"z  
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public void run() 5eC5oX>  
{
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//获得文件长度 y(:hN)  
//分割文件 sBIqee'T  
//实例FileSplitterFetch z[Kxy1,  
//启动FileSplitterFetch线程 +w/Ax[K  
//等待子线程返回 Ep}KIBBO  
try{ |}*k|  
if(bFirst) %E7+W{?*1  
{
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nFileLength = getFileSize(); ->}K-n ),  
if(nFileLength == -1) qEE3x>&T]  
{ Z*kGWL  
System.err.println("File Length is not known!"); i:WHql"Kw_  
} V/+r"le  
else if(nFileLength == -2) ~?vm97l  
{ :~^ec|tp  
System.err.println("File is not access!"); qy@gW@IU  
} |xH"Xvp:  
else J`O4]XRY  
{ M[_~7~4  
for(int i=0;i<nStartPos.length;i++) xIF z@9+k  
{ RlX;c!K  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); GI$t8{M  
} ',0~\V  
for(int i=0;i<nEndPos.length-1;i++) )BTJs)E  
{ ]}9y>+>  
nEndPos = nStartPos[i+1]; $B4}('&4FQ  
} `QR2!W70o3  
nEndPos[nEndPos.length-1] = nFileLength; iQ-;0<=G  
} n?pCMS|  
} i{VjSWq  
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//启动子线程 Ts;W,pgP  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]t1)8v2w>  
for(int i=0;i<nStartPos.length;i++) N|Ua|^  
{ ywk;  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Qd!;CoOmZs  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 44?5]C7  
nStartPos,nEndPos,i); 6!bA~"N  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (k M\R|  
fileSplitterFetch.start(); Xr M[8a  
} KLqu[{y.'  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ;sNyN#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); iTD}gC  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", P1 (8foZA  
nEndPos = " + nFileLength); > Q@*o  
// fileSplitterFetch[nPos.length-1].start(); S:vv*5  
{H $\,  
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//等待子线程结束 c ~YD|l  
//int count = 0; ^V_acAuS^  
//是否结束while循环 v!@/  
boolean breakWhile = false; /^uvY  
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while(!bStop) ACl:~7;  
{ \\hZlCV,  
write_nPos(); GQ|kcY=  
Utility.sleep(500); -5vc0"?E  
breakWhile = true; T|ZZkNP|6  
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for(int i=0;i<nStartPos.length;i++) 'cw0Fp
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{ <l wI|<  
if(!fileSplitterFetch.bDownOver) I6y&6g  
{ yc]ni.Hz  
breakWhile = false; "XC6 l4Z  
break; H gNUr5p  
} h#]}J}si  
} <mY`<(bc  
if(breakWhile) <?qmB}Y  
break; J-?\,N1R7  
N>ct`a)BD/  

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//count++; -#gb {vj  
//if(count>4) ZFW}Vnl  
// siteStop(); {K3\S 0L  
} dN |w;|M  
//ZB B,[@  
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System.err.println("文件下载结束！"); 308w0eP  
} ?]9uHrdsN}  
catch(Exception e){e.printStackTrace ();} .
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} Q=PaTh   
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//获得文件长度 (= !_5l  
public long getFileSize() D4'XBXmb  
{ f!LZT!y  
int nFileLength = -1; crgYr$@s?  
try{ [b#jw,7  
URL url = new URL(siteInfoBean.getSSiteURL());  b1[U9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 5)$U<^uy  
httpConnection.setRequestProperty("User-Agent","NetFox"); /=e[(5X|O  
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int responseCode=httpConnection.getResponseCode(); j~Gu;%tq  
if(responseCode>=400) bq(*r:`"  
{ g=U?{<8.m  
processErrorCode(responseCode); X'?v8\mPK  
return -2; //-2 represent access is error &2xYG{Z  
} Jh466; E  
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String sHeader; }(o/+H4  
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for(int i=1;;i++) =r-Wy.a@  
{ 3gabk/  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); W^=8
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//Utility.log(in.readLine()); $\^]MxI  
sHeader=httpConnection.getHeaderFieldKey(i); V'mpl  
if(sHeader!=null) r`B+ KQ4  
{ e#nTp b  
if(sHeader.equals("Content-Length")) 3&y u  
{ 3@"VS_;?  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); iL,3g[g  
break; ItaJgtsV  
} A\#?rK  
} <BU|?T6~  
else 'h= >ej*  
break; iMA)(ZS  
} %BG5[XQ7  
} xrX("ili  
catch(IOException e){e.printStackTrace ();} O4E2)N  
catch(Exception e){e.printStackTrace ();} |@ldXuYb  
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Utility.log(nFileLength); T=R
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return nFileLength; &pba~X.u  
} 2(c#m*Q!b  
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//保存下载信息（文件指针位置） ,3n}*"K  
private void write_nPos() ffB]4  
{ xK y<o  
try{ A&M/W'$s  
output = new DataOutputStream(new FileOutputStream(tmpFile)); BuvBSLC~  
output.writeInt(nStartPos.length); zp9 ?Ia  
for(int i=0;i<nStartPos.length;i++) o>*{5>#k'  
{ ]_pL79y  
// output.writeLong(nPos); 7>~iS@7GV  
output.writeLong(fileSplitterFetch.nStartPos); 0[i]PgIH  
output.writeLong(fileSplitterFetch.nEndPos); ]Aluk|"`U  
} z::2O/ho  
output.close(); C=b5[, UCB  
} 785iY865  
catch(IOException e){e.printStackTrace ();} r9t{/})A  
catch(Exception e){e.printStackTrace ();} *FE<'+%  
} [ho'Pc3A<  
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//读取保存的下载信息（文件指针位置） tV,zz;* Oe  
private void read_nPos() /<2_K4(-{4  
{ 0iB1
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try{ tQ|I$5jNJ  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Y~:7l5C  
int nCount = input.readInt(); kL3=7t^ 1  
nStartPos = new long[nCount]; & vIKNGJ^  
nEndPos = new long[nCount]; a,E;R$[!  
for(int i=0;i<nStartPos.length;i++) Sh*P^i.]+  
{ ^\6UTnS.  
nStartPos = input.readLong(); TSk6Q'L\v  
nEndPos = input.readLong(); l )4OV>  
} \mDm*UuG  
input.close(); PaZYs~EO  
} SeTU`WLEm  
catch(IOException e){e.printStackTrace ();} y5ExEXa  
catch(Exception e){e.printStackTrace ();} <?g{Rn  
} Rq9gtx8,=  
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private void processErrorCode(int nErrorCode) C;ye%&g>  
{ W9D)QIqbvW  
System.err.println("Error Code : " + nErrorCode); l
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} 19vD(KC<  
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gf=*m"5  
//停止文件下载 Pn#Lymxh_a  
public void siteStop() pZjFpd|  
{ [~o3S$C&7  
bStop = true; -+=8&Wa  
for(int i=0;i<nStartPos.length;i++) Ygl!fC 4b  
fileSplitterFetch.splitterStop(); {HU48v"W  
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} `otQ'e~+t  
} *k}d@j,*"  
//负责部分文件的抓取 ~h/U ;Da  
**FileSplitterFetch.java UGMdWq  
*/ gkdjH8
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package NetFox; o(zg_!P  
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import java.io.*; vKC>t95  
import java.net.*; 4kM<L}J#  
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public class FileSplitterFetch extends Thread { g;h&Xkp  
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String sURL; //File URL t|m3b~Oyv  
long nStartPos; //File Snippet Start Position $3ILVT  
long nEndPos; //File Snippet End Position 1:t>}[Y  
int nThreadID; //Thread's ID m+=!Z|K  
boolean bDownOver = false; //Downing is over S`G\Cd;5  
boolean bStop = false; //Stop identical [ZbK)L+_  
FileAccessI fileAccessI = null; //File Access interface &)l:m.  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException * y B-N;I  
{ K
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this.sURL = sURL; &g!/@*[Nhh  
this.nStartPos = nStart; C0%%
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this.nEndPos = nEnd; ?2TH("hV$  
nThreadID = id; Z7^}G=*  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 #O WSy'Qnt  
} [;I8ZVE  
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public void run() K?4(ou  
{ n3N"Ax  
while(nStartPos < nEndPos && !bStop) YUE[
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{ qo;\dp1  
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try{ TRZ^$<AG  
URL url = new URL(sURL); vF&b|V+,  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Nz;;X\GI  
httpConnection.setRequestProperty("User-Agent","NetFox"); c0 |p34  
String sProperty = "bytes="+nStartPos+"-"; tp<VOUa  
httpConnection.setRequestProperty("RANGE",sProperty); [P/gM3*'  
Utility.log(sProperty); v(iUo&Ge  
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InputStream input = httpConnection.getInputStream(); 3_$eQ`AAA  
//logResponseHead(httpConnection); Ub,unU  
"}! rM6 h  
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byte[] b = new byte[1024]; SOmn2 }   
int nRead; [/G;XHL;?  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) B]7jg9/  
{ Kxn7sL$]=F  
nStartPos += fileAccessI.write(b,0,nRead); o3=kF  
//if(nThreadID == 1) u$#7W>R  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1RA$hW@}  
}
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Utility.log("Thread " + nThreadID + " is over!"); Pc'?p  
bDownOver = true; N+5^h(~  
//nPos = fileAccessI.write (b,0,nRead); gEP E9ew  
} %S.U`(.  
catch(Exception e){e.printStackTrace ();} vXbT E$
  
} aTsfl  
} J|-HZ-Wk|J  
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//打印回应的头信息 y6}):|  
public void logResponseHead(HttpURLConnection con) SK52.xXJ  
{ 4Z}{hc\J  
for(int i=1;;i++) F/sBr7I  
{ mx~sxYa  
String header=con.getHeaderFieldKey(i); d&`j8O  
if(header!=null) jm\#($gl=  
//responseHeaders.put(header,httpConnection.getHeaderField(header));  #Uh5tc  
Utility.log(header+" : "+con.getHeaderField(header)); "ux]kfoT  
else %%6('wi  
break; c'";36y  
} dH|^\IQ  
} e-9unnk  
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public void splitterStop() K"7;Y#1g  
{ K/`RZ!  
bStop = true; z :v, Vu  
} v
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} rz{'X d  
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/* (PcK(C!}=\  
**FileAccess.java tr8Cx~<  
*//文件访问(定位，写) +f!,K  
package NetFox; F|TMpH/  
import java.io.*; "R@N|Qx'  
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public class FileAccessI implements Serializable{ vN:[  
)C]&ui~1  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ?VQLY=?  
RandomAccessFile oSavedFile;  /;6@M=6u  
long nPos; 0WE1}.J<  
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public FileAccessI() throws IOException vUe *  
{ Fx5d@WNa>  
this("",0); 6L9[U^`@  
} FLI8r:  
p''"E$B/(  
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public FileAccessI(String sName,long nPos) throws IOException  x9"4vp  
{ wI@I(r~g  
oSavedFile = new RandomAccessFile(sName,"rw"); ]^jdO##M  
this.nPos = nPos; u#WTh%/  
oSavedFile.seek(nPos); W#I:j: p  
} ,M.!z@  
qlITQKGG  
:
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public synchronized int write(byte[] b,int nStart,int nLen) 6\fMzm  
{ RS `9?c:  
int n = -1; U qw}4C/0  
try{ 8KwCwv  
oSavedFile.write(b,nStart,nLen); ;'QY<,p[e  
n = nLen; e ]o'i;I  
} ~X<cG=p~u  
catch(IOException e) 7[v@*/W@  
{ !{tiTA  
e.printStackTrace (); )9L pX  
} F4E3c4 81  
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return n; i4zV
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} Qy5Os?9"  
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} |\|)j>[i  
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/* @ Rx6 >52>  
**SiteInfoBean.java |4S?>e  
*/ !Nl.Vb  
package NetFox; M*|VLOo=v  
}"?nU4q;S  
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public class SiteInfoBean { )R8%'X;U  
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!\-4gr?`!  
private String sSiteURL; //Site's URL KU|BT.o8  
private String sFilePath; //Saved File's Path }PQSCl^I  
private String sFileName; //Saved File's Name 
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private int nSplitter; //Count of Splited Downloading File 4s~HfxYT  
#CA%]*l
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public SiteInfoBean() 3<Z'F}lg  
{//nSplitter的缺省值为5 AwXt @!(  
//default value of nSplitter is 5 !Wixs]od   
this("","","",5); + sywgb)  
} &^7uv0M<y  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) G_M:0YI@  
{ QGr\I/Y  
sSiteURL= sURL; 3g0u#t{  
sFilePath = sPath; HS\3)Ooj>  
sFileName = sName; =,4 '"  
this.nSplitter = nSpiltter; ,<$YVXe/  
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} xY2}Wr j,  
f `y" a@  
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public String getSSiteURL() sB( `[5I  
{ s[3![ "^Y  
return sSiteURL; s~LZOPN  
} Z .bit_(  
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}KA-t}8  
public void setSSiteURL(String value) '<%Nw-  
{ "*w)puD  
sSiteURL = value; j,=*WG  
} ?"
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public String getSFilePath() T9z4W]T  
{ fW.GNX8
 
return sFilePath; ,@Fgr(?'`>  
} p@/(.uE  
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public void setSFilePath(String value) (_w %  
{ ZcMj=#i  
sFilePath = value; ls"b#eFC#  
} 5pRY&6So  
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public String getSFileName() TBZ-17+  
{ 3(!/["@7  
return sFileName; IXZ(]&we
 
} Vk-W8[W 7  
~reQV6oQua  
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public void setSFileName(String value) vpm ]9>1[  
{ *o02!EYge  
sFileName = value; H]_WFiW-9  
} vWU%
ST  
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+_qh)HX  
public int getNSplitter() ytjK++(T5  
{ H\^VqNK"
 
return nSplitter; k> b&xM!  
} -3.UE^W2  
61/)l0<;  
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public void setNSplitter(int nCount) h?0F-6z  
{ g1ZV&X=2  
nSplitter = nCount; Abj97S  
} Z-(} l2\  
} s$DGd T)  
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/* bh6d./  
**Utility.java >0PUWr$8  
*/ f.||PH  
package NetFox; LthGZ|>  
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public class Utility { nQ5N=l  
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public Utility() 9nn>O?  
{ bvl~[p$W3  
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} f hQy36i@  
7}Bj|]b)~  
//线程睡眠 }>V/H]B  
public static void sleep(int nSecond) MZT6g.ny  
{ a3Y{lc#z}  
try{ )ZHc$+fU  
Thread.sleep(nSecond); &yE1U#J(  
} $+Vmw
d;  
catch(Exception e) '!!e+\h#  
{ Sv7 i! j  
e.printStackTrace ();  bRN
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} @]f3|>I  
} u7HvdLql  
%yiD~
&  
//日志 |/VL35b  
public static void log(String sMsg) Uz 0W <u3v  
{ tpXa*6  
System.err.println(sMsg); NCa~#i:F8  
} A2y6UzLYD  
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2\VAmPG.Zs  
public static void log(int sMsg) Yx5J$!Ld  
{ 4E
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System.err.println(sMsg); ejVdxVr\7  
} 5MxH)~VQoM  
} W
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{O)YwT$`  
MY!q%  
/* Va7c#P?  
**TestMethod.java u?F (1iN=  
*/ =p]mX)I_  
package NetFox; )!e3.C|V1W  
9 ~~qAoD  
^]6M["d/p  
public class TestMethod { ABc)2"i:*  
RlrZxmPV>O  
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public TestMethod() V
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{ ///xx/weblogic60b2_win.exe v dU%R\  
try{ a9=>r  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 8lwFAiC8  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5);
}!8nO;  
SiteFileFetch fileFetch = new SiteFileFetch(bean); d<x1*a  
fileFetch.start(); ;hwzYXWF  
} 3cqQL!Gm  
catch(Exception e){e.printStackTrace ();} i'HPRY

 
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} ?q_^Rj$  
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public static void main(String[] args) zsDocR   
{ %zzYleJ!]  
new TestMethod(); ;WD,x:>blO  
} f^p^Y F+  
} EUy(T1Cl&&  
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