http断点续传简单实现（java)

/* r$#G%FMv  
**SiteFileFetch.java Z M+Hb_6f  
*/ tRy D@}  
package NetFox; FR}H$R7#  
import java.io.*; .?
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import java.net.*; &1p8#i  
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public class SiteFileFetch extends Thread { yo*iv+l  
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SiteInfoBean siteInfoBean = null; //文件信息Bean
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long[] nStartPos; //开始位置 aVP|:OAj  
long[] nEndPos; //结束位置 &5.~XM;  
FileSplitterFetch[] fileSplitterFetch; //子线程对象  4Z}bw#  
long nFileLength; //文件长度 VDTY<= Q  
boolean bFirst = true; //是否第一次取文件 hf<$vRti>  
boolean bStop = false; //停止标志 UPKi/)C;  
File tmpFile; //文件下载的临时信息 &Bn; Vi  
DataOutputStream output; //输出到文件的输出流 ^@Qi&g`lr?  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ^2r}_AX  
public SiteFileFetch(SiteInfoBean bean) throws IOException ;1.>"zX(  
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siteInfoBean = bean; <s-@!8*(  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Uxemlp%%*  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 5b#6 Y
 
if(tmpFile.exists ()) qP"JNswI_  
{ X[Ek'=}  
bFirst = false; =4e=wAO(i  
read_nPos(); -L9R&r#_e  
} 8'lhp2#h  
else DLY
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{ Uk:.2%S2  
nStartPos = new long[bean.getNSplitter()]; z`/.v&<>V  
nEndPos = new long[bean.getNSplitter()]; <8)s  
} F36ViN\b  
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} HqdJdWl#"  
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public void run() t;!]z-Y>  
{ ^ 6.lb\  
//获得文件长度 dPx<Dz;  
//分割文件 ?Y{^un  
//实例FileSplitterFetch z9 w&uZzi  
//启动FileSplitterFetch线程 ~u0xXfv#  
//等待子线程返回 A,gx5!J  
try{ .NkAD-k`  
if(bFirst) P/pjy  
{ y5/6nvH_6  
nFileLength = getFileSize(); 6!B^xm.R@  
if(nFileLength == -1) (
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{ @%<?GNSO  
System.err.println("File Length is not known!"); yvz?4m"_yB  
} u5Ny=Xm  
else if(nFileLength == -2) 5w3ZUmjO  
{ `<J#l;y  
System.err.println("File is not access!"); v (ka,Dk3  
} irsfJUr[V  
else _;:rkC fj  
{ +%wWSZ<#  
for(int i=0;i<nStartPos.length;i++)  Wu!t C  
{ s^>
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); N\q)LM !M  
} iS"8X#[]N  
for(int i=0;i<nEndPos.length-1;i++) D;zWksq  
{ 5!AV!A_Jp  
nEndPos = nStartPos[i+1]; d;~ 3P   
} rer|k<k;]G  
nEndPos[nEndPos.length-1] = nFileLength; voV:H[RD9  
} -+}5ma  
} jJVT_8J  
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i<m$#6<Z  
//启动子线程 +~d1;0l|  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; |qlS6Aln  
for(int i=0;i<nStartPos.length;i++)
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{ e8WEz 4r_  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), kT^*>=1  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ku9@&W+  
nStartPos,nEndPos,i); nlzW.OLM  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ALd]1a&  
fileSplitterFetch.start(); ]jc_=I6)  
} Xlv#=@;O]  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -\kXH"%  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); BR36}iS
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", )C {h1 `  
nEndPos = " + nFileLength); pp~3@_)b  
// fileSplitterFetch[nPos.length-1].start(); QqtC`H\  
h2wN<dJCM  
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//等待子线程结束 r<*O  
//int count = 0; rH_Jh}Y  
//是否结束while循环 lq>pH5x  
boolean breakWhile = false; YwL`>?  
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while(!bStop) )N(9pnyZH  
{ (kI

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write_nPos(); pI7Ssvi^  
Utility.sleep(500); y"^yYO  
breakWhile = true; Di*]ab  
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for(int i=0;i<nStartPos.length;i++) ImIqD&a-h  
{ w[(n>  
if(!fileSplitterFetch.bDownOver) {-@~Q.&}v  
{ NZLXN  
breakWhile = false; [pii  
break; 2sKG(^=Z  
} .^i<
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} XRa(sXA3  
if(breakWhile) pW\z\o/2  
break; -bypuMQ-p  
*URdd,){i  
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//count++; L[9OVD  
//if(count>4) iTh xVD  
// siteStop(); P##Z[$IJ3  
} #?9Q{0e  
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System.err.println("文件下载结束！"); a3q\<"|  
} (ZV;$N-t  
catch(Exception e){e.printStackTrace ();} HZ }6Q  
} E0QPE5_  
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//获得文件长度 pOMgEEhfS  
public long getFileSize() 2"@Ft()]  
{ K;x~&G0=  
int nFileLength = -1; cw;co@!$  
try{ GR%{T'ZD`  
URL url = new URL(siteInfoBean.getSSiteURL()); b,dr+RB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }W$8M>l  
httpConnection.setRequestProperty("User-Agent","NetFox"); i\Yl  
{I{3(M#"  
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int responseCode=httpConnection.getResponseCode(); zmI5"K"
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if(responseCode>=400) XA1f' Kk  
{ JA`H@qE  
processErrorCode(responseCode); JSgpb?(  
return -2; //-2 represent access is error =}v
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} h*s`^W3
 
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String sHeader; IIxJqGN:  
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for(int i=1;;i++) <F7V=Er  
{ R
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Uky9zGa  
//Utility.log(in.readLine()); uEx9-,!  
sHeader=httpConnection.getHeaderFieldKey(i); -`7$Qu2  
if(sHeader!=null)
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{ VD$Eb  
if(sHeader.equals("Content-Length")) mV?&%>*(f  
{ /s|{by`we4  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); :
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break; R"+wih  
} o.Oq__>$H  
} Nb;H`<JP  
else 3]/.\(2  
break; +TN^NE  
} tPU-1by$  
} bLbR IY"l  
catch(IOException e){e.printStackTrace ();} 6tn+m54_  
catch(Exception e){e.printStackTrace ();} t
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Utility.log(nFileLength); 9tK>gwb  
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return nFileLength; -7%X]  
} ffE#^|  
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//保存下载信息（文件指针位置） *Qkc[XHqy  
private void write_nPos() t> . Fl-  
{ 3b!,D  
try{ gnLn7?  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 40#9]=;}  
output.writeInt(nStartPos.length); SEM8`lnu  
for(int i=0;i<nStartPos.length;i++) C\Vg{&'  
{ .Evy_o\^  
// output.writeLong(nPos); 6~8F!b2  
output.writeLong(fileSplitterFetch.nStartPos); %NajFjBI  
output.writeLong(fileSplitterFetch.nEndPos); nt ,7u(  
} *1^$.Q&  
output.close(); cp6WMHLj   
} >72JV;W]  
catch(IOException e){e.printStackTrace ();} 30Drrno7Io  
catch(Exception e){e.printStackTrace ();} r:&|vP  
} xAhxD|4_  
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//读取保存的下载信息（文件指针位置） CQ^3v09N;~  
private void read_nPos() Qi9-z'
 
{ E0l_--  
try{ \
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); qZk:mlYd  
int nCount = input.readInt(); A\$ >>Z  
nStartPos = new long[nCount]; P)6lu8zQ  
nEndPos = new long[nCount]; t6lE#<xZV;  
for(int i=0;i<nStartPos.length;i++) n~gLPHY  
{ Vz%OV}\  
nStartPos = input.readLong(); \9:wfLF8!  
nEndPos = input.readLong(); TDNf)Mm  
} x/mp=   
input.close(); L{8;Ud_2r  
} bwiD$  
catch(IOException e){e.printStackTrace ();} E(^0B(JF  
catch(Exception e){e.printStackTrace ();} v]"L]/"  
} L}%dCe  
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private void processErrorCode(int nErrorCode) +?m0Q;%b  
{ ]lBGyUJn  
System.err.println("Error Code : " + nErrorCode); 6bO~/mpWT~  
} /)>
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r&3pM2Da}  
r"{<%e  
//停止文件下载 pyZ9OA!PD  
public void siteStop() o[\HOe~;  
{ p9qKLJ*.C  
bStop = true; $m| V :/  
for(int i=0;i<nStartPos.length;i++) d8o53a]  
fileSplitterFetch.splitterStop(); -db75=  
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} mD58T2Z  
} jd-glE,Y/  
//负责部分文件的抓取 K^[#]+nQ  
**FileSplitterFetch.java LnsD  
*/ Ao9R:|9  
package NetFox; DcD{*t?x  
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import java.io.*; l$xxrb9P!  
import java.net.*; GqKsK r2%  
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public class FileSplitterFetch extends Thread { w#y0atsg'  
}8K4-[\  
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String sURL; //File URL b=;nm#cAI  
long nStartPos; //File Snippet Start Position /+]s.V.  
long nEndPos; //File Snippet End Position s +s" MI  
int nThreadID; //Thread's ID C.Uju`3  
boolean bDownOver = false; //Downing is over pB:$lS  
boolean bStop = false; //Stop identical b1#dz]  
FileAccessI fileAccessI = null; //File Access interface e [h8}F  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException c=O,;lWFqm  
{ &a0r%L()X  
this.sURL = sURL; 'tgKe!-@  
this.nStartPos = nStart; Guw}=l--YR  
this.nEndPos = nEnd; )cJ#-M2  
nThreadID = id; !YL..fb  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 XOP"Px@  
} hfWFD,  
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public void run() 7, } $u  
{ 8IQtz2  
while(nStartPos < nEndPos && !bStop) A7_4.VH  
{ ZP\M9Ja  
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try{ {Ro2ouQ!V  
URL url = new URL(sURL); 1T&Rc4$Sn7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ]}="
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httpConnection.setRequestProperty("User-Agent","NetFox"); `r"+644  
String sProperty = "bytes="+nStartPos+"-"; gV;H6"  
httpConnection.setRequestProperty("RANGE",sProperty); e}Vw!w  
Utility.log(sProperty); B!]2Se2G  
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InputStream input = httpConnection.getInputStream(); &)wiKh"$  
//logResponseHead(httpConnection); }Db[ 4
 
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byte[] b = new byte[1024]; {P%9  
int nRead; u7%D6W~m0  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) IY'=DePd  
{ zG }?  
nStartPos += fileAccessI.write(b,0,nRead); f"G-  
//if(nThreadID == 1) CvSIV7zYo  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8`>h}Q$  
} 5zJj]A  
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Utility.log("Thread " + nThreadID + " is over!");
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bDownOver = true; #AkV/1Y  
//nPos = fileAccessI.write (b,0,nRead); Y_&g="`Q  
} !l?.5Pm])  
catch(Exception e){e.printStackTrace ();} $4kH3
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} 8I20*#  
} GG064zPq7  
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//打印回应的头信息 bK"SKV  
public void logResponseHead(HttpURLConnection con) i$G;f^Z!Y  
{ XgN` 7!Z  
for(int i=1;;i++) h+p*=|j`  
{ u@'0Vk0zGH  
String header=con.getHeaderFieldKey(i); :NHH Dl  
if(header!=null) xJ^>pg8  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); l:
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Utility.log(header+" : "+con.getHeaderField(header)); [v7^i_d  
else $E<Esf$  
break; fqX"Lus `=  
} y.5/?{GL  
} }VS3L_ ;}/  
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public void splitterStop() l
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{ LZJA4?C  
bStop = true; Ee)[\Qjn  
} Ds#/  
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} OaJB=J%  
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/* t"h
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**FileAccess.java KoE8Mp  
*//文件访问(定位，写) T{V/+RM  
package NetFox; 8`4<R6]LKB  
import java.io.*; M` q?Fk  
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public class FileAccessI implements Serializable{ B\J^=W+`  
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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 _J
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RandomAccessFile oSavedFile; NaVQ9ku7VW  
long nPos; F(4?tX T  
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public FileAccessI() throws IOException V/cP4{L  
{ rG#Z=*b%  
this("",0); @L.82p{h  
} G+B~Ix-  
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public FileAccessI(String sName,long nPos) throws IOException ,yd MU\so(  
{ ]| N3eu  
oSavedFile = new RandomAccessFile(sName,"rw"); ^~{$wVGa  
this.nPos = nPos; a+hd(JX0~  
oSavedFile.seek(nPos); o]nw0q?  
} `cPywn@uGZ  
rl9.]~  
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public synchronized int write(byte[] b,int nStart,int nLen) uwRr LF  
{ fLV"T_rk  
int n = -1; %6AW7q t  
try{ KD/V aN  
oSavedFile.write(b,nStart,nLen); R'
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n = nLen; (D@A74q\'  
} /R>nr"  
catch(IOException e) MCU_Z[N#10  
{ *~m+Nc`D,N  
e.printStackTrace (); b-3*Nl_%  
} TKk-;Y=N  
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return n; D:Q 21Ch  
} Ib
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} D")_;NLE1  
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/* ,K:ll4{b  
**SiteInfoBean.java #gm)dRKm%  
*/ kId n6 Wx,  
package NetFox; A AHt218  
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public class SiteInfoBean { mhW-J6u*  
)'*5R<#  
9-]i.y  
private String sSiteURL; //Site's URL w8g,a]p  
private String sFilePath; //Saved File's Path ^F:k3,_[  
private String sFileName; //Saved File's Name DE2a5+^  
private int nSplitter; //Count of Splited Downloading File rP!#RzL  
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public SiteInfoBean() BTM), w2  
{//nSplitter的缺省值为5 `/HUV&i"S  
//default value of nSplitter is 5 WM)-J^)BJ  
this("","","",5); 9;?UvOI;  
} XUuu-wm:}  
97K[(KE  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) a>mm+L8y  
{ C&++VRnm  
sSiteURL= sURL; ~rjTF!  
sFilePath = sPath; 5OoN!TEM  
sFileName = sName; }du XC[6  
this.nSplitter = nSpiltter; :VF<9@t  
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} jE#O>3+.  
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public String getSSiteURL() *xp\4;B  
{ }E`dZW*!!  
return sSiteURL; G;f/Tch  
} {QCf}@_]h  
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public void setSSiteURL(String value) tK k#LWB  
{ ?BhMjsy.  
sSiteURL = value; 5=e@d:Sz  
} WcC?8X2  
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public String getSFilePath() uUKc
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{ 3=W!4  
return sFilePath; >J u]2++lx  
} :_Eqf8T  
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public void setSFilePath(String value) wO2_DyMm@  
{ KRjV}\}  
sFilePath = value; =}PdH`S  
} BcD&sQ2F  
)]#aauC+  
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public String getSFileName() 5XLs}:  
{ nk3y"ne7  
return sFileName; *Sh^J+j  
} xG;-bJu  
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public void setSFileName(String value) '_b.\_s-d  
{ /*|oL#hK  
sFileName = value; ~{}#)gGU  
} Y<0 4RV  
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public int getNSplitter() f{0F|w<gf  
{ GUQ{r!S  
return nSplitter; 4Z|vnj)Z  
} ~
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public void setNSplitter(int nCount) @AYRiOodi  
{ J~(Wf%jM~  
nSplitter = nCount; 7^T^($+6s&  
} zS]8V?`  
} mw5?[@G-  
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/* CkswJ:z)sc  
**Utility.java .G o{1
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*/ F7")]q3I~  
package NetFox; ;O<9|?  
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public class Utility { 5{$LsL  
OxGE
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public Utility() W[+|}
 
{ V(Yxh+KU  
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} [=%TnT+^9  
_20#2i&  
//线程睡眠 i_][PTH  
public static void sleep(int nSecond) w{k)XY40sW  
{ dJ?XPo"Cm=  
try{ y<C<_2  
Thread.sleep(nSecond); cQ:"-!ff  
} gT/@dVV  
catch(Exception e) RmrL^asg  
{ yz2Ci0Dwy  
e.printStackTrace (); :iR \%  
} !gnj]k&/c  
} |j3'eW&=  
wM_c48|d  
//日志 <5=JE*s$NS  
public static void log(String sMsg) /*Qq[C  
{ *-s,. F+c  
System.err.println(sMsg); OiDhJ  
} 8>/Q1(q0  
#P#-xz  
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public static void log(int sMsg) Z!0]/mCE8  
{ lcV<MDS  
System.err.println(sMsg); ET];%~ ^  
} &uUo3qXQ5l  
} >yJ9U,Y  
dz>;<&2Z  
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/* PA w-6;  
**TestMethod.java _7DkS}NJs  
*/ CQ;]J=|<_  
package NetFox; A8A~!2V  
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@Mvd'.r<;  
public class TestMethod { i ZL2p>  
c"!lwm3b  
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public TestMethod() Z>)][pL  
{ ///xx/weblogic60b2_win.exe G;3~2^lB\  
try{ zY+Fl~$S  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); >+5?F*`\D*  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); jEXW  
SiteFileFetch fileFetch = new SiteFileFetch(bean); y$81Zq  
fileFetch.start(); ,&U4a1%i#c  
} Hqh6:
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catch(Exception e){e.printStackTrace ();} V0nn4dVO  
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74  
} G#Ou[*O'  
#G
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public static void main(String[] args) <\zCpkZ'B  
{ D}3XFuZs_  
new TestMethod(); 6a}"6d/sTL  
} midsnG+jnf  
} TO,rxf  
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