http断点续传简单实现（java)

/* dl6d!Nz*  
**SiteFileFetch.java JD^(L~n]  
*/ CZS{^6Ye  
package NetFox; )K4 |-<i  
import java.io.*; w<|^i*  
import java.net.*; ?A3pXa  
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public class SiteFileFetch extends Thread { _}vD?/$L  
FQ*4?D,A  
9P#E^;L  
SiteInfoBean siteInfoBean = null; //文件信息Bean _iO,GT=J-  
long[] nStartPos; //开始位置 =P<gZ-Cm  
long[] nEndPos; //结束位置 Wt"fn&R}  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 :CNHN2 J  
long nFileLength; //文件长度 a<B[~J4i  
boolean bFirst = true; //是否第一次取文件 X@*$3z#Z  
boolean bStop = false; //停止标志 5P,{h  
File tmpFile; //文件下载的临时信息 l(-6pP5`  
DataOutputStream output; //输出到文件的输出流 .:B] a7b  
?J<Y]  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） \`Db|D?oy  
public SiteFileFetch(SiteInfoBean bean) throws IOException ?a+tL'D[  
{ &~29%Ns  
siteInfoBean = bean; *Sm$FMWQ  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); FYFP6ti  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); \H!ECTI  
if(tmpFile.exists ()) hyH"  
{ n\Uh5P1W"  
bFirst = false; %fGS< W;  
read_nPos(); R+ lwOVX  
} ZqsI\
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else CLg;  
{ >?ZH[A  
nStartPos = new long[bean.getNSplitter()]; h3$.` >l  
nEndPos = new long[bean.getNSplitter()]; U N1HBW;  
} : |#Iw  
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} UN>!#Ji:$  
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public void run() 4&~ft  
{ 0K <@?cI  
//获得文件长度 ?"]fGp6y  
//分割文件 Jtnuo]{R  
//实例FileSplitterFetch Uc/MPCqZ  
//启动FileSplitterFetch线程 'j6PL;~c  
//等待子线程返回 ?g+0S@{i $  
try{ 8l-+ 4~mH  
if(bFirst) j(HC^\Hi  
{ (D]l/akP  
nFileLength = getFileSize(); Q/o!&&  
if(nFileLength == -1) Z"<aS&GH  
{ kz\ D-b  
System.err.println("File Length is not known!"); j(F
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} DBANq\  
else if(nFileLength == -2) 9->E$W  
{ ;Oh4W<hH}  
System.err.println("File is not access!"); <i``#"/  
} 3P-qLbJ  
else ]1>U@oK  
{ :A%uXgK<k  
for(int i=0;i<nStartPos.length;i++) TBHIcX
 
{ eN fo8xUG  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); b*S:wfw  
} ,'?%z>RZm  
for(int i=0;i<nEndPos.length-1;i++) 7^P!@o$v!  
{ Pou-AzEP$  
nEndPos = nStartPos[i+1]; >Ip>x!wi  
} Qctm"g|  
nEndPos[nEndPos.length-1] = nFileLength; =|O`al  
} `X'-4/Y  
} !Sx}~XB<  
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:j)H;@[I
 
//启动子线程 S^? @vj  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ?}\aG3_4  
for(int i=0;i<nStartPos.length;i++) |q"WJQ  
{ /bv
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -H5n>j0!{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Wu(6FQ`H  
nStartPos,nEndPos,i); -&I%=0q  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); w-*$gk]  
fileSplitterFetch.start(); ^UHt1[  
}
*9M 5'  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 'L4@|c~x  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 9`yG[OA  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", i,=greA]"  
nEndPos = " + nFileLength); xa#0y  
// fileSplitterFetch[nPos.length-1].start(); ;A7
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5<\&7P3y  
//等待子线程结束 Y0fX\6=h  
//int count = 0; xZZW*d_b  
//是否结束while循环 Is&z~Xy/  
boolean breakWhile = false; ESp)%  
~n9BN'@x  
L!s/0kBg  
while(!bStop) ,R]hNjs-{  
{ S G|``}OA  
write_nPos(); Tu2BQ4\[  
Utility.sleep(500); Fn.wd`'0  
breakWhile = true; E,&BP$B  
zim]3%b*A;  
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for(int i=0;i<nStartPos.length;i++) Y+75}]B  
{ DP**pf%j  
if(!fileSplitterFetch.bDownOver) YzJ\< tkp  
{ _Bm/v^(  
breakWhile = false; N+%E=D>  
break; :=WiT_M  
} RO"c+|Py  
} E:/G!1  
if(breakWhile) :bFCnV`Q  
break; 3qU#Rg ;7  
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Fw? ;Y%  
//count++; ]4wyuP,up  
//if(count>4) >F+Mu-^  
// siteStop(); 8##-fv]  
} I)Y ^_&=  
,4wVQ(,?cd  
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System.err.println("文件下载结束！"); 9,wd,,ta  
} n*~=O'  
catch(Exception e){e.printStackTrace ();} F`KA^ZI  
} ,DsqKXSU  
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+>mbBu!7  
//获得文件长度 +ptVAg+
 
public long getFileSize() 3;(;'5|Z  
{ ?n<b:oO  
int nFileLength = -1; I:l<t*  
try{ 2Pn  
URL url = new URL(siteInfoBean.getSSiteURL()); /T&z :st0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); TD:NL4dm  
httpConnection.setRequestProperty("User-Agent","NetFox"); l]D?S]{a  
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?;Dh^mc  
int responseCode=httpConnection.getResponseCode(); /
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if(responseCode>=400) 'X&sH/>r  
{ ov&4&v  
processErrorCode(responseCode); cr
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return -2; //-2 represent access is error o&}!bq]  
} dx}) 1%  
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String sHeader; F0h`>{1%  
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for(int i=1;;i++) oe,I vnt  
{ `t_S uZ`V  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); zvv<w@rX  
//Utility.log(in.readLine()); jf25Ky~  
sHeader=httpConnection.getHeaderFieldKey(i); ]G.ttfC  
if(sHeader!=null) SXkUtY$  
{ 1vKc>+9  
if(sHeader.equals("Content-Length")) (n:d {bKV  
{ _Kdqa%L !  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); (XW\4msB)I  
break; 6d/;GyG  
} AuIb>@a  
} 3\_ae2GW  
else T(t@[U2^  
break; kSx^Uu*  
} 7x`dEi<  
}
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catch(IOException e){e.printStackTrace ();} w@w(AFV9/  
catch(Exception e){e.printStackTrace ();} i}teY{pyc  
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Utility.log(nFileLength); v5STe`  
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return nFileLength; mLApF5Hy  
} LVNq@,s  
j\l9|vpp  
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//保存下载信息（文件指针位置） &4 Py  
private void write_nPos() / blVm1F  
{ YjaEKM8*  
try{ R gY-fc0  
output = new DataOutputStream(new FileOutputStream(tmpFile)); r}kQ<SRx  
output.writeInt(nStartPos.length); xCU^4DO3p  
for(int i=0;i<nStartPos.length;i++) q =sEtH=  
{ Qvc "?yx8}  
// output.writeLong(nPos); K;,zE6WD$$  
output.writeLong(fileSplitterFetch.nStartPos); lbM)U  
output.writeLong(fileSplitterFetch.nEndPos); A[lbBR  
} d%1Tv1={  
output.close(); ~uy{6U{&I  
} [vMksHk4  
catch(IOException e){e.printStackTrace ();} xs+pCK|  
catch(Exception e){e.printStackTrace ();} 0/{$5gy&  
} .B2?%2S  
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//读取保存的下载信息（文件指针位置） +M4X r*  
private void read_nPos() ' >a(|  
{ { FVLH:{U^  
try{ }
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); n0|oV
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int nCount = input.readInt(); \Tf[% Kt x  
nStartPos = new long[nCount]; ~)>O=nR  
nEndPos = new long[nCount]; fik*-$V`  
for(int i=0;i<nStartPos.length;i++) GIXxOea1  
{ 1k-YeQNe  
nStartPos = input.readLong(); VB 53n'  
nEndPos = input.readLong(); Yq~$Q4  
} j8Nl'"  
input.close(); wz1fx>Q  
} `/]Th&(5  
catch(IOException e){e.printStackTrace ();} #p'Xq }]  
catch(Exception e){e.printStackTrace ();} * V;L|c  
} oU/CXz?H  
Vl=!^T}l+  
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private void processErrorCode(int nErrorCode) Yrl
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{ "^sh:{  
System.err.println("Error Code : " + nErrorCode); 6z;C~_BV  
} u!kC+0Y  
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,w>WuRN"  
//停止文件下载 5=< y%VF  
public void siteStop() @9-/p^n1  
{ h SGI  
bStop = true; ]O%wZIp\P  
for(int i=0;i<nStartPos.length;i++) PL+r*M%ll  
fileSplitterFetch.splitterStop(); 9A|deETa-  
Rb!|2h)  
5]C}044  
} WhPwD6l>  
} 3FWl_d~uD  
//负责部分文件的抓取 sEBZ-qql  
**FileSplitterFetch.java /u hA\m(  
*/ uu08q<B5b)  
package NetFox; tE&@U$0>o  
""AP-7  
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import java.io.*; w[`2t{^j  
import java.net.*; Po+I!TL'  
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Fk&W*<}/;  
public class FileSplitterFetch extends Thread { i%~^3/K  
)=,%iL-  
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String sURL; //File URL n*%o!=  
long nStartPos; //File Snippet Start Position }^T7S2_Qy  
long nEndPos; //File Snippet End Position Zp5;=8wa;  
int nThreadID; //Thread's ID eN*=wOh  
boolean bDownOver = false; //Downing is over NBLiwL37{  
boolean bStop = false; //Stop identical 8:W,""  
FileAccessI fileAccessI = null; //File Access interface ;ZnSWIF2  
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_
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 4k}3^.#  
{ )-2sk@y  
this.sURL = sURL; .I~#o$6  
this.nStartPos = nStart; ZkbaUIQ  
this.nEndPos = nEnd; [VvTR#^  
nThreadID = id; $e(]L(o;  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 jg2UX  
} &/%A 9R,  
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~ ^)D#Lo  
public void run() xZmO^F5KHj  
{ x3./  
while(nStartPos < nEndPos && !bStop) Cxn<#Kf\-<  
{ FG-v71!h#  
q_0So}  
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try{ YH_m
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URL url = new URL(sURL); |r5e#3w  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); kNC.^8ryz[  
httpConnection.setRequestProperty("User-Agent","NetFox"); d!BQ%a  
String sProperty = "bytes="+nStartPos+"-"; .Vohd@s9l  
httpConnection.setRequestProperty("RANGE",sProperty); "nkj_pC  
Utility.log(sProperty); 0Dx,)C  
{2|[7oNT6  
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InputStream input = httpConnection.getInputStream(); j41)X'MgJ  
//logResponseHead(httpConnection); {zTo[i  
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byte[] b = new byte[1024]; ld RV JVZc  
int nRead; J[Ckz]  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) [ " n+2;  
{ +[LG>  
nStartPos += fileAccessI.write(b,0,nRead); Vrwy+o>:X  
//if(nThreadID == 1) -4rXOmiA  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); :v=^-&t  
} n*'i{P]  
,F&TSzH[@v  
O)0}yF$0  
Utility.log("Thread " + nThreadID + " is over!"); @D?KS;#  
bDownOver = true; =rw60B  
//nPos = fileAccessI.write (b,0,nRead); E_fH,YJ?9  
} |E%i t?3M  
catch(Exception e){e.printStackTrace ();} x,U'!F  
} 0_!')+  
} (d> M/x?W  
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{6_M$"e.  
//打印回应的头信息 8R3x74fL  
public void logResponseHead(HttpURLConnection con) kIC$ai6.  
{ O\3 Lx  
for(int i=1;;i++) |4$.mb.  
{ 8OS@gpz  
String header=con.getHeaderFieldKey(i); ,M4G_U[  
if(header!=null) lpjeEawo4  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Ri<7!Y?l  
Utility.log(header+" : "+con.getHeaderField(header)); fX ^hO+f
 
else .Y
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break; }9Th`   
} iMT[sb  
} "aU) [  
q=EHB5!q  
=:w]EpH"  
public void splitterStop() `u<\ 4&W  
{ G_vcuCHm  
bStop = true; @3^D[  
} ?%|w?Fdx-  
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} 9\QeH'A  

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/* e9LP!"@EY  
**FileAccess.java S'%|40U  
*//文件访问(定位，写) -qbx:Kk(  
package NetFox; F K7cDaI  
import java.io.*; v>X
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4
# L}
&  

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public class FileAccessI implements Serializable{ pmWt7 }  
+jEtu[ ;  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 9}[
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RandomAccessFile oSavedFile; tj'xjX  
long nPos; VRb+
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public FileAccessI() throws IOException R&-Vm3mc3  
{  &x":  
this("",0); ?Z0NHy;5  
} \80W?9qj  
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public FileAccessI(String sName,long nPos) throws IOException #JAy  
{ wHT]&fZ  
oSavedFile = new RandomAccessFile(sName,"rw"); {4y#+[  
this.nPos = nPos; 
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oSavedFile.seek(nPos); #VvU8"u  
} } SNZl`>  
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public synchronized int write(byte[] b,int nStart,int nLen) 9hTzi+'S  
{ Z!& u_  
int n = -1; /<R[X>]<F  
try{ mA?fCs  
oSavedFile.write(b,nStart,nLen); 8|"26UwD/  
n = nLen; t=;P1d?E;  
} 1_jd1UT  
catch(IOException e) NimW=X;c  
{
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e.printStackTrace (); {f(RYj  
} .eHOG]H  
:~{Nf-y0`1  
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return n; J#*%r)  
} <2V:tj)?P  
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} 2.2G79U,  
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/* Q1'4xWu  
**SiteInfoBean.java W^k|*Y|  
*/ *}P=7TuS  
package NetFox; 3FgTM(  
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public class SiteInfoBean { JQ%D6b  
%B~@wcI)W  
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private String sSiteURL; //Site's URL lDX\"Fq  
private String sFilePath; //Saved File's Path _/5#A+ ?  
private String sFileName; //Saved File's Name SjL&\),
 
private int nSplitter; //Count of Splited Downloading File ?/1Eu47  
P?o|N<46  
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public SiteInfoBean() | zyO;  
{//nSplitter的缺省值为5 vveL|j  
//default value of nSplitter is 5 nJhaI  
this("","","",5); (3Dz'X  
} o()No_.8H  
d=DQS>Nz  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Fz{T;  
{ i}gsxq%  
sSiteURL= sURL; 'Z8=y[l  
sFilePath = sPath; #8/pYQ;  
sFileName = sName; V^%P}RFMc  
this.nSplitter = nSpiltter; 7t3ps  
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vACJE  
} \(&UDG$  
:[J'B4>9  
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public String getSSiteURL() G -V~
6  
{  va[r~  
return sSiteURL; T&nIH[}v  
} ".7\>8A#a  
8)ykXx/f@  
mlO\wn-F  
public void setSSiteURL(String value) ?`/DFI'_G  
{ &e\
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sSiteURL = value; X.GK5Phd  
} uZml.#@4  
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O^~Z-;FA  
public String getSFilePath() E*"oA1/
I  
{ >/+R~ n  
return sFilePath; 6hiWgbE  
} 1d 1 ~`B  
4ATIF;G'<  
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public void setSFilePath(String value) mMw--Gc?  
{ ECk* H  
sFilePath = value; #D
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} K"jS,a?s 6  
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public String getSFileName() uE,g|51H/  
{ |c[= V?AC  
return sFileName; )?{jD  
} `hf`l
q^  
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Th!;zu^t  
public void setSFileName(String value) -<l2 $&KS  
{ Wi@YJ  
sFileName = value; oV'G67W  
} I+/fX0-Lib  
:E.T2n
a  
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public int getNSplitter() 9~{,Hj1xE  
{ zG)vmysJf  
return nSplitter; aen0XiB6~^  
} lkW5<s_  
>o1,Y&  
uvl>Z= "  
public void setNSplitter(int nCount) 2j&0U!DX  
{ 6xLQ  
nSplitter = nCount; wpg7xx!  
} }`y%*--  
} o8X? 1  
5KTPlqm0qF  
0"{-<Wot}  
/* \U>|^$4 #5  
**Utility.java G_`Ae%'h  
*/ |RL\2j|  
package NetFox; _+OCI%=:  
Zi}jf25  
E:y^= Y  
public class Utility { n.XgGT=L  
,uPN\`.u8  
,AH2/^:%c  
public Utility() q[(1zG%NbA  
{ 05Q4$P  
biPj(Dd  
 I)MRAo  
} {f\{{JJ]  
%c@PTpAM  
//线程睡眠 bwI"V
&*  
public static void sleep(int nSecond) m=25HH7enb  
{ ^% L;FGaA  
try{ hi/Z>1ZOX  
Thread.sleep(nSecond); Z^Yy sf  
} Xp9] 9H.  
catch(Exception e) tgj5l#P  
{ LIll@2[  
e.printStackTrace (); F!g;}_s9  
} P$.$M}rMv  
} LqLhZBU9  
F*_+k  
//日志 m'-QVZ{(M%  
public static void log(String sMsg) Z7I
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{ yL
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System.err.println(sMsg); <cxe   
} <cO `jK  
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public static void log(int sMsg) BO2s(8  
{ R$`%<Y3)  
System.err.println(sMsg); R'pfA B|!  
} M+I9k;N6&  
} ,/&|:PkS  
_WZ{i,  
sR^b_/ElxT  
/* t'Zv)Wu1E  
**TestMethod.java ]Upr<!  
*/ vl~HV8MAv  
package NetFox; UW1i%u k  
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public class TestMethod { |;\pAZ2  
y&/bp<Z  
MnlD87x@X  
public TestMethod() ]WK~`-3C^  
{ ///xx/weblogic60b2_win.exe ZYt1V"2VJ  
try{ WD1>{TSn  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 1'P4{T0 [  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); nNeCi  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ,~/WYw<o  
fileFetch.start(); NKc<nYdK?  
} (*kKfg4Wj  
catch(Exception e){e.printStackTrace ();} nd$92
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} 4C )sjk?m  
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public static void main(String[] args) zK>m4+)~  
{ CM7Nd
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new TestMethod(); \58bz<u"  
} U "r)C;
5  
} ;NQ}c"9  
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