http断点续传简单实现（java)

/* %koHTWT+  
**SiteFileFetch.java =uIu0_v  
*/ QY/36gK  
package NetFox; 4JT9EKo
 
import java.io.*; K.dgQ-vn  
import java.net.*; -_4U+Cfmtl  
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public class SiteFileFetch extends Thread { Ck/4hZ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean U;LbP-{B  
long[] nStartPos; //开始位置 m("! M~1  
long[] nEndPos; //结束位置 Jx[
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 =k2In_  
long nFileLength; //文件长度 bWW$_Spr  
boolean bFirst = true; //是否第一次取文件 qWfG@hn  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 '&xv)tno  
DataOutputStream output; //输出到文件的输出流 K\`L>B. 1  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） !/BXMj,=  
public SiteFileFetch(SiteInfoBean bean) throws IOException ezY _7  
{ "'~'xaU!=a  
siteInfoBean = bean; JD^(L~n]  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); N;9@-Tb  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); wh<+.Zp  
if(tmpFile.exists ()) ,9`sC8w|  
{ oL
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bFirst = false; }`{aeVHT  
read_nPos(); ? !MDg_oHd  
} \8'fy\  
else e #>wv]V  
{ 6NVf&;laQ  
nStartPos = new long[bean.getNSplitter()]; {*r*+}@  
nEndPos = new long[bean.getNSplitter()]; `Jq ?+W  
} tq8B)<(]  
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} /o*r[g7<  
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public void run() `i<;5s!rX  
{ j{C+`~O
 
//获得文件长度 ?H#]+SpOcv  
//分割文件 4/e-E^  
//实例FileSplitterFetch HW;,XzP=  
//启动FileSplitterFetch线程 ;X[mfg\  
//等待子线程返回 /8VM.fr$  
try{ wyzj[PDS  
if(bFirst) Eb7qM.Q] &  
{ l4I
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nFileLength = getFileSize(); ZTfs&5  
if(nFileLength == -1) D0Oh,Fe#M\  
{ <(TTYf8lS  
System.err.println("File Length is not known!");  (f,D$mX  
} 0Y,_ DU  
else if(nFileLength == -2) 7?:7}xb-  
{ iov55jT~l@  
System.err.println("File is not access!"); rZ
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} E5w.wx  
else 0(iTnzx0  
{ 6.kX~$K  
for(int i=0;i<nStartPos.length;i++) RMMx6L|-:  
{ a)$"  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ?%J{1+hY  
} -ve{
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for(int i=0;i<nEndPos.length-1;i++) gk>-h,
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{ 1a;Le8  
nEndPos = nStartPos[i+1]; 7^4F,JuJO  
} 4\H:^U&  
nEndPos[nEndPos.length-1] = nFileLength; 2-Y%W(bEzs  
} f^@`[MJj1C  
} oj /:  
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//启动子线程 (Hb i+IHV  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 8zS't2 u  
for(int i=0;i<nStartPos.length;i++) AdxCP\S&  
{
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $`W.9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), U$@p"F@P  
nStartPos,nEndPos,i); )sWdN(E3  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "K5n|{#  
fileSplitterFetch.start(); x48Y#"'  
} L:"i,K#P  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), J?&lpsB3_l  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 7d*SZmD   
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Ml1yk)3G  
nEndPos = " + nFileLength); ER~m &JI  
// fileSplitterFetch[nPos.length-1].start(); uh*b[`e  
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<"Z]S^>$  
//等待子线程结束 L!x7]g,^  
//int count = 0; T%A45BE V  
//是否结束while循环 :[z=u  
boolean breakWhile = false; KY9sa/xO  
q$`{$RX  
]#]|]>& <  
while(!bStop) NWd%Za5K;  
{ +VE }c  
write_nPos(); qMD6LWJ  
Utility.sleep(500); *T' /5,rX2  
breakWhile = true; u1s^AW8 y  
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for(int i=0;i<nStartPos.length;i++) h4N!zj[  
{ o65:)z u  
if(!fileSplitterFetch.bDownOver) {Hm0Q  
{ u;18s-NY  
breakWhile = false; %wn|H>  
break; %p6"Sg*  
} [,e[~J`C  
} m:CiXM   
if(breakWhile) i$gm/ZO  
break; r\Nf309~  
!7"-9n  
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//count++; Ve#VGlI  
//if(count>4) /_}xTP"9  
// siteStop(); teH $hd-q  
} FZ'|z8Dm  
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t  
System.err.println("文件下载结束！"); z6 2gF|Uj  
} F#>?i}  
catch(Exception e){e.printStackTrace ();} ig:,:KN  
} A ^@:Ps  
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//获得文件长度 xtMN<4#E  
public long getFileSize() _Bm/v^(  
{ L"6qS3[=  
int nFileLength = -1; :=WiT_M  
try{ RO"c+|Py  
URL url = new URL(siteInfoBean.getSSiteURL()); E:/G!1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :bFCnV`Q  
httpConnection.setRequestProperty("User-Agent","NetFox"); 3qU#Rg ;7  
q'~?azg:  
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int responseCode=httpConnection.getResponseCode(); Njsz
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if(responseCode>=400) Tn2nd  
{ >fRI^Q,  
processErrorCode(responseCode); Q/&H3N  
return -2; //-2 represent access is error sN0S~}F+  
} N
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String sHeader; %>Z;/j|#r  
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for(int i=1;;i++) b)RU+9x &  
{ OEmz`JJ67  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); J4 [7*v  
//Utility.log(in.readLine()); UUi@ U  
sHeader=httpConnection.getHeaderFieldKey(i); GADbXp3  
if(sHeader!=null) \o3)\ e]o  
{
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if(sHeader.equals("Content-Length")) dYV'<  
{ S~fURn  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); !i=LQUi.  
break; 8?#4<4Ql8  
} Kcv7C{-/  
} V)#se"GV  
else lj0"2@z3"E  
break; 6p`AdDV  
} [mX/]31  
} }9yAYZ0q{b  
catch(IOException e){e.printStackTrace ();} !wy 
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catch(Exception e){e.printStackTrace ();} Y^DS~CrM  
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9  
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Utility.log(nFileLength); {`5Sh1b  
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return nFileLength; u:#+R_0#97  
} \|9@*]6:  
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//保存下载信息（文件指针位置） h{xC0NC)  
private void write_nPos() ParOWs~W/  
{ 6)63Yp(  
try{ [r,a0s  
output = new DataOutputStream(new FileOutputStream(tmpFile)); fa7Z=:aG  
output.writeInt(nStartPos.length); hbm%{*d  
for(int i=0;i<nStartPos.length;i++) ^UI{U1N~Bz  
{ 70bI}/u  
// output.writeLong(nPos); dl_ h0  
output.writeLong(fileSplitterFetch.nStartPos); 
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output.writeLong(fileSplitterFetch.nEndPos); OI0#@_L&  
} 2z9\p%MX  
output.close(); _K"|}bM  
} W>3[+wB
 
catch(IOException e){e.printStackTrace ();} e~C5{XEE  
catch(Exception e){e.printStackTrace ();} I^erMQn[ z  
} _~V
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//读取保存的下载信息（文件指针位置） I\djZG$s;N  
private void read_nPos() 1OB,UU"S$  
{ OUCLtn\  
try{ c'M#va  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); #x-@ >{1k&  
int nCount = input.readInt();  1@Abs  
nStartPos = new long[nCount]; +vOlA#t%Z  
nEndPos = new long[nCount]; w#]> Nf  
for(int i=0;i<nStartPos.length;i++) /@Qg'Q#  
{ -6lsR  
nStartPos = input.readLong(); (iub\`  
nEndPos = input.readLong(); uYjE)"  
} _IzJxAcJ  
input.close(); y+b4sFf  
} 9gNQ,c \gT  
catch(IOException e){e.printStackTrace ();} <vxj*M;  
catch(Exception e){e.printStackTrace ();} 7)&}riQ  
} _'
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private void processErrorCode(int nErrorCode) 533n z8&9@  
{ E"d\N-I  
System.err.println("Error Code : " + nErrorCode); _<tWy+.  
} :|cC7,S  
X(sHFVU+  
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//停止文件下载 kA3nhBH  
public void siteStop() 6*yt^[W  
{ Qtj.@CGB  
bStop = true; eeKErpj8A  
for(int i=0;i<nStartPos.length;i++) zN}1Qh  
fileSplitterFetch.splitterStop(); A+3,y<j\  

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} b[5$$_[  
} R@*mMWW,  
//负责部分文件的抓取 Ky"]L~8$  
**FileSplitterFetch.java * V;L|c  
*/ oU/CXz?H  
package NetFox; tQ!p<Q= $)  
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import java.io.*;
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import java.net.*; -+vA9,pI  
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public class FileSplitterFetch extends Thread { _X ?W)]:  
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String sURL; //File URL b{T". @b  
long nStartPos; //File Snippet Start Position b4TZnO  
long nEndPos; //File Snippet End Position qg521o$*  
int nThreadID; //Thread's ID $ = uz  
boolean bDownOver = false; //Downing is over :r5DR`Rfm  
boolean bStop = false; //Stop identical K)NB{8 _  
FileAccessI fileAccessI = null; //File Access interface B[XV
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException >`\f,yql6  
{ 06hzCWm#  
this.sURL = sURL;
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this.nStartPos = nStart; =&Dt+f&  
this.nEndPos = nEnd; "ecG\}R=  
nThreadID = id; -nBb -y  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ZR|)+W;  
} q. zBm@:  
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public void run() kjCXP  
{ &)(>e}es  
while(nStartPos < nEndPos && !bStop) 2|="!c8K  
{ :exgdm;N  
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try{ 82w;}(!  
URL url = new URL(sURL); lr>:S  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); SZ/}2_;  
httpConnection.setRequestProperty("User-Agent","NetFox"); P''5A6#5  
String sProperty = "bytes="+nStartPos+"-"; :.;pRz  
httpConnection.setRequestProperty("RANGE",sProperty); 4<`Qyul-  
Utility.log(sProperty); t(<^
of:  
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InputStream input = httpConnection.getInputStream(); bCv=Uo,+6  
//logResponseHead(httpConnection); DV={bcQ  
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byte[] b = new byte[1024]; P'EPP*)q  
int nRead; n^} -k'l  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) fY)Dx c&ue  
{ <n8K"(sy}  
nStartPos += fileAccessI.write(b,0,nRead); w$ zX.;s  
//if(nThreadID == 1) nIRJ5|G(  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); !v^{n+  
} U<
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)Dg;W6  
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Utility.log("Thread " + nThreadID + " is over!"); "nkj_pC  
bDownOver = true; 0Dx,)C  
//nPos = fileAccessI.write (b,0,nRead); _G$SA-W(  
} ->BGeP_=|  
catch(Exception e){e.printStackTrace ();} Y|'0bujr  
} 9\yGv  
} "c0I2wq  
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yH\3*#+  
//打印回应的头信息 'VgdQp$L$  
public void logResponseHead(HttpURLConnection con) M @|n"(P  
{ IJWUNKqo=  
for(int i=1;;i++) H2f!c{t$p  
{ jkTh)
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String header=con.getHeaderFieldKey(i); P}YtT3.K  
if(header!=null) *u?QO4>  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 2#<)-Cak  
Utility.log(header+" : "+con.getHeaderField(header)); c"nowbf  
else h
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break; |2i=oX(r|  
} wiwAdYEQ\  
} dC&OjBQ  
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public void splitterStop() \a_75^2  
{ e(e_p#  
bStop = true; `"7}'|  
} 7P+qPcRaP  
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4tQ~Z6Jn;  
} J$aE:g6'  
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/* S]}hh,A  
**FileAccess.java w^AY= Fc  
*//文件访问(定位，写) 
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package NetFox; TFfV?rBI  
import java.io.*; `l#|][B)g$  
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public class FileAccessI implements Serializable{ @3^D[  
?%|w?Fdx-  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 _u[2R=h  
RandomAccessFile oSavedFile; 1g{-DIOmn  
long nPos; Nldy76|g  

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public FileAccessI() throws IOException s6U$]9 `  
{ lQ8h-Tz  
this("",0); h_( #U)z_3  
} $wr B5m?  
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m{ wk0  
public FileAccessI(String sName,long nPos) throws IOException
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{ pmWt7 }  
oSavedFile = new RandomAccessFile(sName,"rw"); +jEtu[ ;  
this.nPos = nPos; 9}[
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oSavedFile.seek(nPos); Q.U wtH  
} '3p7ee&  
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public synchronized int write(byte[] b,int nStart,int nLen) 1*aO2dOq  
{ B~CdY}UTsj  
int n = -1; & t.G4  
try{ 5[[mS  
oSavedFile.write(b,nStart,nLen); ]ZMFK>"^%  
n = nLen; RXi/&'+H  
} )Ja&Y  
catch(IOException e) =O1py_m  
{ W0I)< S  
e.printStackTrace (); PM?F;mj  
} K9HXy*y49  
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return n; -MK9IO]i  
} ee}HQ.}Ja  
? PI2X.6  
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} fi,h`mdT?  
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; u@& [  
/* t@;r~Sb  
**SiteInfoBean.java 5r)]o'?s  
*/ RPB%6z$  
package NetFox; t:O"t G  
KLBX2H2^0  
( kKQs")  
public class SiteInfoBean { ^.pd'  
+_T`tmQ  
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private String sSiteURL; //Site's URL ;:]#Isq  
private String sFilePath; //Saved File's Path 3J_BuMV  
private String sFileName; //Saved File's Name F1q6 3  
private int nSplitter; //Count of Splited Downloading File s=H|^v  
}0oVIr  
tW -f_0a.  
public SiteInfoBean() QFNw2:)  
{//nSplitter的缺省值为5 [["az'Lrk?  
//default value of nSplitter is 5 IA;'5IF  
this("","","",5); c gOkm}h  
} \Q!
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) p.|M:C\xL  
{ q2e=(]rKE{  
sSiteURL= sURL; ZnAXb S  
sFilePath = sPath; ccY! OSae  
sFileName = sName; | zyO;  
this.nSplitter = nSpiltter; vveL|j  
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} o()No_.8H  
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public String getSSiteURL() Fz{T;  
{ i}gsxq%  
return sSiteURL; 'Z8=y[l  
} #8/pYQ;  
V^%P}RFMc  
}pJLK\  
public void setSSiteURL(String value) asZ(Hz%  
{ vACJE  
sSiteURL = value; \(&UDG$  
} GWa:C\YK  
?0x=ascP  
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public String getSFilePath()  va[r~  
{ 928uGo5  
return sFilePath; l{mC|8X  
} EdTR]}8  
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public void setSFilePath(String value)
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{ %PlA9@:IZ  
sFilePath = value; [T(`+ #f  
} O8k+R@  
z'9U.v'M)  
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public String getSFileName() <lgX=wx L  
{ vLs*}+f  
return sFileName; c->.eL%   
} /^sk y!  
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public void setSFileName(String value) 0fog/c#q(  
{ BMO&(g  
sFileName = value; >zo_}A!  
} Z</57w#-7  
)Ah7  
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public int getNSplitter() 2GxkOch  
{ Z 5 Xis"j  
return nSplitter; d:#z{V_  
} 1\Z/}FT  
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/8wfI_P>M"  
public void setNSplitter(int nCount) uQYenCNXS  
{ ?UV|m  
nSplitter = nCount; b

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} Kz"&:&R"  
} Nj{;  
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/* aen0XiB6~^  
**Utility.java n.=Zw2F
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*/
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package NetFox; y&(pt!I  
.Vrl:  
OCELG~  
public class Utility { <-DQ(0xg  
9p,PWA  
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public Utility() o8X? 1  
{ "j8`)XXa(  
0"{-<Wot}  
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} ?4
#UW7I  
#$;}-*  
//线程睡眠 "hnvND4=  
public static void sleep(int nSecond) V8rS~'{\  
{ i`5Skr:M  
try{ &Qmb?{S0  
Thread.sleep(nSecond); $IqubC>O  
} :{9HsF"h0  
catch(Exception e) z@?W
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{ )jj
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e.printStackTrace (); yN/g;bQ  
} ]wwNmmE  
} XEBj=5sG  
=E62N7_`=  
//日志 jLn|zK  
public static void log(String sMsg) !JtM`x/yR  
{ B,]
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System.err.println(sMsg); 3oV2Ek<d  
} 3+&k{UZjt  
t +|t/1s2  
&F8*>F^7  
public static void log(int sMsg) v]#[bqB.b  
{ 2({|LQqk  
System.err.println(sMsg); n~ZZX={a  
} <}G/x*N  
} rv c%[HfW;  
1DlXsup&?#  
=7[}:haB{  
/* Zb&"W]HSf  
**TestMethod.java A b+qLh&?  
*/ ^VEaOKMr  
package NetFox; V -_MwII-  
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public class TestMethod { ;I*N%a TK  
v'm-A d+4t  
yxi&80$  
public TestMethod() %,S{9q  
{ ///xx/weblogic60b2_win.exe o]WcODJdl  
try{ y>cLG5v  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); #jsN  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Bus]OF>hu  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 4dy!2KZN  
fileFetch.start(); Wt.['`c<  
} 7K1_$vd  
catch(Exception e){e.printStackTrace ();} Pif-uhOk%  
%rV|{@J `  
<zm:J4&>T  
} fmD~f  
+BDW1%  
$)$_}^.k  
public static void main(String[] args) I+( b!(H  
{ E;,__  
new TestMethod(); -d-xsP} s  
} Q.fUpa v  
} Q5A
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