http断点续传简单实现（java)

/* 7<:w-  
**SiteFileFetch.java 2RXGY  
*/ et ~gO!1:*  
package NetFox; ta6WZu  
import java.io.*; z=Vvb  
import java.net.*; w./EJkKI  
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public class SiteFileFetch extends Thread { O}f(h5!k  
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SiteInfoBean siteInfoBean = null; //文件信息Bean +@qk=]3a  
long[] nStartPos; //开始位置 ]D-4
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long[] nEndPos; //结束位置 XP;&iZJ  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 YXg uw7%\  
long nFileLength; //文件长度 M2EN(Y_k0  
boolean bFirst = true; //是否第一次取文件 ?Ru`ma\;  
boolean bStop = false; //停止标志 I2DmM"-|  
File tmpFile; //文件下载的临时信息 aQ
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DataOutputStream output; //输出到文件的输出流 d=KOV;~);  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） lM1!2d'P  
public SiteFileFetch(SiteInfoBean bean) throws IOException R39R$\  
{ 5)oIPHXw  
siteInfoBean = bean; B:r-')!0$#  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); "=n8PNV/ c  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); TxCQGzqe  
if(tmpFile.exists ()) eo_T.q  
{ 2M#CJ&  
bFirst = false; Y)*lw  
read_nPos(); ZAH<!@qh  
} O({_x@  
else jgo@~,5R  
{ -9*WQU9R  
nStartPos = new long[bean.getNSplitter()]; l9ihW^  
nEndPos = new long[bean.getNSplitter()]; _Lb& 2PAG  
} *pD;AU  
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} `s_TY%&_}g  
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public void run() yrs3`/  
{ X[
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//获得文件长度 g[jZ A[[  
//分割文件 ggTjd"|)  
//实例FileSplitterFetch ncdr/(`  
//启动FileSplitterFetch线程 W7o/  
//等待子线程返回 {|E7N"Qzg  
try{ ,h._iO)I^  
if(bFirst) {LD8ie|x1`  
{ KTEis!w  
nFileLength = getFileSize(); VT7NWTJ,  
if(nFileLength == -1) "'#Hh&Us  
{ \-0`%k"&  
System.err.println("File Length is not known!"); rw2|1_AF  
} DS2$w9!  
else if(nFileLength == -2) L>b,}w  
{ "y0A<-~  
System.err.println("File is not access!"); 9.=#4OH/  
} \IfgL$+  
else (B-9M)  
{ 5w1[KO#K|  
for(int i=0;i<nStartPos.length;i++) ,R =VzP&  
{ ~\G3l,4  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); sD3|Qj;  
} xH[yIfHkG@  
for(int i=0;i<nEndPos.length-1;i++) __iyBaX  
{ \^4$}@*]  
nEndPos = nStartPos[i+1]; o?FUVK  
} (`+Z'Y  
nEndPos[nEndPos.length-1] = nFileLength; xlO2jSSAt  
} SXz([Z{)  
} }aM`Jp-O  
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//启动子线程 B
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; UYOn p7R<  
for(int i=0;i<nStartPos.length;i++)  vB*oI~<  
{ 8!6*|!,:?n  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), XE*bRTEw  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), *^Y0}?]qT  
nStartPos,nEndPos,i); 3raA^d3!?  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^b %8_?2m  
fileSplitterFetch.start(); gu[dw3L  
} Vb9N~v  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), RAI&;"  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1);
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 30E v"  
nEndPos = " + nFileLength); 34Khg  
// fileSplitterFetch[nPos.length-1].start(); +yH~G9u(  
)>5k'1  
u/c3omY"#  
//等待子线程结束 ]Hy PJ  
//int count = 0; ]/Qy1,  
//是否结束while循环 MwqT`;lb  
boolean breakWhile = false; a[g|APZz  
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while(!bStop) (v:ek_  
{ ja- ~`  
write_nPos(); b_Jq=Gk`  
Utility.sleep(500); +|YZEC  
breakWhile = true; Q5n :f+  
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for(int i=0;i<nStartPos.length;i++) mS}x2&  
{ `j}d=zZ  
if(!fileSplitterFetch.bDownOver) b|o!&9Yyr  
{ TeCpT2!5j  
breakWhile = false; .<^YE%  
break; /'fDXSdP  
} {WeXURp&nF  
} `lezJ(Xm  
if(breakWhile) 7O{O')o!  
break; ?lN8~Ze  
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/8t+d.r;/  
//count++; l)*,18n  
//if(count>4) cievC,3*  
// siteStop(); CN~NyJL H  
} PFy;qk  
65#:2,s  
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System.err.println("文件下载结束！"); / &D$kxz  
} \R\@t]>Y  
catch(Exception e){e.printStackTrace ();} L2.`1Aag  
} .`>
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//获得文件长度 TTZxkK  
public long getFileSize() F*JvpI[7n  
{ (2bZ]  
int nFileLength = -1; !aw#',r8m  
try{ N^(lUba  
URL url = new URL(siteInfoBean.getSSiteURL()); l()MYuLNV  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 2, "q_d'V  
httpConnection.setRequestProperty("User-Agent","NetFox"); ,,gLrVk  
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int responseCode=httpConnection.getResponseCode(); [7Lx
t
 
if(responseCode>=400) @U3foL2\  
{ k;_KKvQ  
processErrorCode(responseCode); EH*ym#Y  
return -2; //-2 represent access is error zB6u-4^wT  
} ~/jxB)t  
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String sHeader; 4[,B;7  
}#HTO:r  
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for(int i=1;;i++) AOlt,MNpQ  
{ Z\=04[  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); j H.Ju|nO  
//Utility.log(in.readLine()); jXY;V3l  
sHeader=httpConnection.getHeaderFieldKey(i); SAG`^
t  
if(sHeader!=null) K+@eH#Cv,(  
{ ]8m_*I!  
if(sHeader.equals("Content-Length")) YP#AB]2\}  
{ O(D5A?tv!  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); mk%"G=w  
break; S`@6c$y k  
} Ur([L&  
} k'ZUBTRq!  
else 3_\{[_W  
break; 2@3.xG  
} $TA6S+  
} gJ3OK!/  
catch(IOException e){e.printStackTrace ();} jxnQG A  
catch(Exception e){e.printStackTrace ();} En,)}yI  
~i }+P71  
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Utility.log(nFileLength); nRXSW&V"m  
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return nFileLength; :qAc= IC%  
} =l8!VJa  
833%H`jQc  
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//保存下载信息（文件指针位置） ! nCjA\$  
private void write_nPos() 7O+Ij9+{n  
{ vdH+>l  
try{ jKj=#O
 
output = new DataOutputStream(new FileOutputStream(tmpFile)); sArje(5Eo  
output.writeInt(nStartPos.length); (lN;xT`=  
for(int i=0;i<nStartPos.length;i++) p<HTJ0  
{ C,{F0-D  
// output.writeLong(nPos); xA&  
output.writeLong(fileSplitterFetch.nStartPos); Cgz&@@j,]  
output.writeLong(fileSplitterFetch.nEndPos); Z\|u9DO  
} h eE'S/  
output.close(); WjY{rM,K  
}  vr{'FMc  
catch(IOException e){e.printStackTrace ();} 5>ADw3z'  
catch(Exception e){e.printStackTrace ();} 0Oc}rRH(C  
} >lraYMc<rZ  
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//读取保存的下载信息（文件指针位置） X`fhln9N  
private void read_nPos() 5@ bc(H  
{ c{
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try{ >P\h,1  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); A,m4WO_q3  
int nCount = input.readInt(); DHm[8 Qp  
nStartPos = new long[nCount]; ~JwpNJs  
nEndPos = new long[nCount]; Mhe|eD#)  
for(int i=0;i<nStartPos.length;i++) (!ZQ  
{ Ig1lol:;  
nStartPos = input.readLong(); <H5n>3#pH  
nEndPos = input.readLong(); aFRTNu/r  
} 9Qzjqq:"Li  
input.close(); y Y>-MoF/t  
} 1 [Sv  
catch(IOException e){e.printStackTrace ();} YVB% kKv{  
catch(Exception e){e.printStackTrace ();} (px*R~}  
} Sc&)~h}YF  
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/7k.r}6\R  
private void processErrorCode(int nErrorCode) r]k*7PK  
{ Kajkw>z  
System.err.println("Error Code : " + nErrorCode); y)3~]h\a  
} 4? m/*VV  
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//停止文件下载 Dq/3E-y5  
public void siteStop() 8W~lU~-  
{ O9t=lrYV!  
bStop = true; N@Xg5huO  
for(int i=0;i<nStartPos.length;i++) DeOXM=&z  
fileSplitterFetch.splitterStop(); '8)Wd"[  
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} koOyZ>  
} jrm0@K+<IA  
//负责部分文件的抓取 H<`^w)?  
**FileSplitterFetch.java 2X|CuL{]  
*/ m_Mwg  
package NetFox; Z0e-W:&;kF  
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import java.io.*; {]&R8?%  
import java.net.*; JAc@S20v\  
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public class FileSplitterFetch extends Thread { ;"1/#CY773  
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String sURL; //File URL 9[z'/U.Bn  
long nStartPos; //File Snippet Start Position /@&(P#h  
long nEndPos; //File Snippet End Position `$J'UXtGc  
int nThreadID; //Thread's ID /^w"' '  
boolean bDownOver = false; //Downing is over a*Rz<08  
boolean bStop = false; //Stop identical Ns'FH(:  
FileAccessI fileAccessI = null; //File Access interface l<:`~\#  
z>6.[Z(T  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException u\`/Nhn  
{ ~6p5H}'H1  
this.sURL = sURL; 6|QTS|!  
this.nStartPos = nStart; /sy-;JDnsu  
this.nEndPos = nEnd; csYy7uzi  
nThreadID = id; r+o_t2_b*  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 X*0k>j  
} wi>DZkR  
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public void run() [!W5}=^H  
{
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while(nStartPos < nEndPos && !bStop) neF8V"-u&  
{ LyIKP$t  
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try{ $nj\\,(g  
URL url = new URL(sURL); V]Sgx00;  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); >wA+[81[  
httpConnection.setRequestProperty("User-Agent","NetFox"); vruD U#  
String sProperty = "bytes="+nStartPos+"-"; 5`"iq "5Cf  
httpConnection.setRequestProperty("RANGE",sProperty); Qe_+r(3)k  
Utility.log(sProperty); 2zhn`m  
^[#=L4  
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InputStream input = httpConnection.getInputStream(); mIvnz{_d  
//logResponseHead(httpConnection); mxgqS
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byte[] b = new byte[1024]; d [r-k 2  
int nRead; J<rlz5':  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) :i.t)ES  
{  m;c3Z-  
nStartPos += fileAccessI.write(b,0,nRead); 6Z Xu,ks}  
//if(nThreadID == 1) x.b
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); hqL+_|DW  
} 8yn4}`Nc@  
/N>} 4Ay  
{#N%Bq}  
Utility.log("Thread " + nThreadID + " is over!"); E30Ln_^o  
bDownOver = true; 0*/kGvw`i  
//nPos = fileAccessI.write (b,0,nRead); $%Z3;:<Uf-  
} 8&%Cy'TIz4  
catch(Exception e){e.printStackTrace ();} JRXRi*@  
} Apmw6cc  
} K U$`!h  
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//打印回应的头信息 n&$/Q$d&  
public void logResponseHead(HttpURLConnection con) Bhe{L?}0  
{ _B3zRO  
for(int i=1;;i++) FNC[59  
{ 1eHe~p ,  
String header=con.getHeaderFieldKey(i); i3P9sdTD  
if(header!=null) Hs$'0:  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~q 7;8<U  
Utility.log(header+" : "+con.getHeaderField(header));
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else UA0F):  
break; afx'  
} 4@h;5  
} uaaf9SL?  
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public void splitterStop() xz8G}Ku  
{ FIS "Z(  
bStop = true; l[oe*aYN7  
} Lc|{aN  
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} &qKigkLd  
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/* ,5{$+  
**FileAccess.java 'C
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*//文件访问(定位，写) p?JQ[K7i  
package NetFox; Z/g]o#  
import java.io.*; >?I/;R.-  
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/P:EWUf'  
public class FileAccessI implements Serializable{ ^s-25 6iI  
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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 h&`y$Jj  
RandomAccessFile oSavedFile; e>AXXUEf  
long nPos; |@wyC0k!  
@^&7$#jq%  
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public FileAccessI() throws IOException YG`?o  
{ kAo.C Nj7  
this("",0); o_$&XNC_  
} ($8t%jVWJJ  
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public FileAccessI(String sName,long nPos) throws IOException y
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{ m*Cu-6&qd  
oSavedFile = new RandomAccessFile(sName,"rw"); QIK 9  
this.nPos = nPos; `N'V#)Pi  
oSavedFile.seek(nPos); ,[l
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} p0VUh!  
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50$W0L$  
public synchronized int write(byte[] b,int nStart,int nLen) )/>A6A:  
{ ~*-qX$gr  
int n = -1; `5l01nOxJ  
try{ T$mbk3P  
oSavedFile.write(b,nStart,nLen); n_23EcSy  
n = nLen; 8:dQ._#v  
} q.W>4 k  
catch(IOException e) p$XKlg&  
{ a <wL#Id  
e.printStackTrace (); {v,)G)obWw  
} -c+]Wm"\  
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return n; v* ~3Z1  
} suVmg-d  
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*x(Jq?5O7X  
} >2lwWXA  
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/* ;gB`YNL  
**SiteInfoBean.java
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*/ rQr!R$t/[  
package NetFox; (MLhaux-  
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public class SiteInfoBean { z7T0u.4Ss  
?9xu{B>6  
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private String sSiteURL; //Site's URL ZA820A>2!  
private String sFilePath; //Saved File's Path |5MbAqjzC  
private String sFileName; //Saved File's Name `^6 ,kI-c  
private int nSplitter; //Count of Splited Downloading File ~ap2m  
<Ef[c@3  
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public SiteInfoBean() :Li/=>R^  
{//nSplitter的缺省值为5 {vVTv SC  
//default value of nSplitter is 5 :]II-$/8  
this("","","",5); NX,-;v  
} qLK?%?.N<  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) L:R<e#kgS  
{ \#Up|u:  
sSiteURL= sURL; DL8x":;  
sFilePath = sPath; @S3f:s0~D
 
sFileName = sName; caq} &A]C  
this.nSplitter = nSpiltter; `JURQ:l)3^  
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j  
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} DBgMC"_   
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public String getSSiteURL() VaLs`q&3>  
{ E6A/SVp  
return sSiteURL; ;['a  
} MesRa(  
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|i7a@'0)  
public void setSSiteURL(String value) iiC!|`k"  
{ D4u%6R|F  
sSiteURL = value; A :e;k{J  
} h~}.G{"  
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public String getSFilePath() PK2~fJB  
{ QP(BZJC  
return sFilePath; l67Jl"v  
} diT=x52  
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public void setSFilePath(String value) u{e-G&]^;  
{ \>Zvev!s  
sFilePath = value; @N.jB#nEb  
} >U!*y4  
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public String getSFileName() lB;FUck9  
{ &^.57]  
return sFileName; z\!K<d"Xv  
} X[3}?,aqL  
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public void setSFileName(String value) 3H
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{ CA s>AXbs  
sFileName = value; ;H0{CkH  
} ko\):DN  
5Av=3[kh"%  
:k=mzO<&  
public int getNSplitter() @{HrJ/4%:&  
{ aUopNmN  
return nSplitter; vqdX^m^PY  
} AC- )BM';  
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public void setNSplitter(int nCount) dJk9@u  
{ ,!QV>=  
nSplitter = nCount; ;0%OB*lcgE  
}  iThSt72  
} 83Ou9E!W  
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/* Bi%x`4Lf  
**Utility.java 1NLg _UBOK  
*/ `ldz`yu6++  
package NetFox; Me3dpF  
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public class Utility { 7(a2L&k^  
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public Utility() tT%/r,  
{ o^p  
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} 2umv|]n+l|  
 #1nJ(-D+  
//线程睡眠 6p;m\  
public static void sleep(int nSecond) ]ZoPQUS?  
{ t#E}NR  
try{ eVh-_  
Thread.sleep(nSecond); Sus;(3EX  
} bZwnaM4"F  
catch(Exception e) ~l E _L1-c  
{ b{7E;KyY,  
e.printStackTrace (); IVxWxM*N<  
} V|D]M{O  
} 7Ke&0eAw  
Jf;?XP]z  
//日志 ){;02^tX  
public static void log(String sMsg) }?8uH/+ZA  
{ Fj p.T;  
System.err.println(sMsg); JCniN";r[  
} 9WG{p[  
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public static void log(int sMsg) pbXi9|bI  
{ aptY6lGv-|  
System.err.println(sMsg); tOl e>]  
} u{H?4|'(  
} ! NV#U  
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j Ch=@<9  
/* Q4]4@96Aj  
**TestMethod.java kLSrj
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*/ ?)4?V\$  
package NetFox; y(jg#7)  
^ZRYRA  
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public class TestMethod { ]2SI!Ai7  
/B3R1kNf|  
^C)n$L>C0  
public TestMethod() '-$XX%TOAc  
{ ///xx/weblogic60b2_win.exe g=@_Z"  
try{ >pL2*O^{9  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); YPDf Y<?v  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); v6(E3)J7  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 256LHY|6  
fileFetch.start(); ~l[ra  
} uq3{hB#  
catch(Exception e){e.printStackTrace ();} mB'3N;~  
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}
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public static void main(String[] args) qQ[b VD\*  
{ 3Hi+Z}8  
new TestMethod(); ],etZ%z&  
} C)-^<  
} \*vHB`.,ey  
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