http断点续传简单实现（java)

/* KE5kOU;  
**SiteFileFetch.java iAEbu&XG  
*/ +US!YU  
package NetFox; :Uzm  
import java.io.*; W.f/pu  
import java.net.*; 9}!qR|l3nR  
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public class SiteFileFetch extends Thread { XFHYQ2ME2  
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SiteInfoBean siteInfoBean = null; //文件信息Bean z,[Hli*0  
long[] nStartPos; //开始位置 [I,Z2G,Jb  
long[] nEndPos; //结束位置 eCDev}  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 D&&9^t9S  
long nFileLength; //文件长度 ifMRryN4  
boolean bFirst = true; //是否第一次取文件 wo;~7K  
boolean bStop = false; //停止标志 7Jyy z,!5  
File tmpFile; //文件下载的临时信息 X; \+<LE  
DataOutputStream output; //输出到文件的输出流 jUYWrYJ  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） SuJ aL-;  
public SiteFileFetch(SiteInfoBean bean) throws IOException &WuN&As!Z  
{ C\Wmq [  
siteInfoBean = bean; +ZaSM~   
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ~?Qe?hB  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); S}m)OmrmA  
if(tmpFile.exists ()) !21FR*  
{ ,GbR!j@6  
bFirst = false; UJAv`yjG  
read_nPos(); }I+E\<  
} / |;RV"  
else _lJ!R:*  
{ mW(W\'~_~  
nStartPos = new long[bean.getNSplitter()]; zx"s*:O
 
nEndPos = new long[bean.getNSplitter()]; FF`T\&u  
} by1<[$8r  
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} .LnGL]/  
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public void run() ok"
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{ b5dD/-Vj  
//获得文件长度 $kdB |4C  
//分割文件 g#pr yYz  
//实例FileSplitterFetch O-0x8O^B  
//启动FileSplitterFetch线程 9]([\%)  
//等待子线程返回 r,8 [O  
try{ 5FPM`hLT  
if(bFirst) B?gOHG*vd>  
{ Drgv`z  
nFileLength = getFileSize(); 6RU~"C  
if(nFileLength == -1) #>("CAB02T  
{ ~|DUt  
System.err.println("File Length is not known!"); UawyDs  
} YlJ@
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else if(nFileLength == -2)
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{ Fh&G;aE
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System.err.println("File is not access!"); Fc)@,/R"v  
} \g`\`e53?  
else d=$Mim  
{ Z!a=dnwHz  
for(int i=0;i<nStartPos.length;i++) PfAgM1  
{ 7FP*oN?  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); $D~0~gn~  
} jE.N ev/  
for(int i=0;i<nEndPos.length-1;i++) Ws3)gvpPA  
{ S:#lH?<_  
nEndPos = nStartPos[i+1]; 13$%,q
)  
} u OmtyX  
nEndPos[nEndPos.length-1] = nFileLength; cN-?l7  
} gS!:+G%  
} t9GR69v:?  
^,lIK+#Elz  
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//启动子线程 HYD'.uj  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; B-Ll{k^  
for(int i=0;i<nStartPos.length;i++) s0TORl6Z|  
{ o=:9y-nH  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7JD' )
 
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ?8H8O %Z8  
nStartPos,nEndPos,i); ]!W=^!  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); dK$XNi13.5  
fileSplitterFetch.start(); %OL$57Ia  
} ^&9zw\x;z  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Hs;4lSyUO  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ^ glri$m  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", %vn"{3y>rF  
nEndPos = " + nFileLength); p;`>e>$  
// fileSplitterFetch[nPos.length-1].start(); j1Y~_  
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//等待子线程结束 hIYNhZv  
//int count = 0; y1jCg%'H  
//是否结束while循环 i<C*j4qQ  
boolean breakWhile = false; UP$.+<vm  
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9d0@wq.  
while(!bStop) =g7x' kN  
{ G{As,`{  
write_nPos(); ih-#5M@  
Utility.sleep(500); gMi
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breakWhile = true; //up5R_nx  
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for(int i=0;i<nStartPos.length;i++) { T/[cu<  
{ P1.[  
if(!fileSplitterFetch.bDownOver) f=l rg KE  
{ nmee 'oEw  
breakWhile = false; |"q5sym8Y_  
break; {LI=:xJJv  
} "@^k)d$  
} np|Sy;:  
if(breakWhile) f=+
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break; `$Y.Y5mGtJ  
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//count++; gi3F` m  
//if(count>4) v4!VrI  
// siteStop(); %"i(K@  
} d(ZO6Nr Q  
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System.err.println("文件下载结束！"); etQCzYIhn  
} udK%>  
catch(Exception e){e.printStackTrace ();} w0 M>[ 4  
} 1;bh^WMJ  
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//获得文件长度 GhAlx/K  
public long getFileSize() A;q9rD,_  
{ Qab>|eSm  
int nFileLength = -1; RXMISt3+{y  
try{ /aCc17>2V{  
URL url = new URL(siteInfoBean.getSSiteURL()); 8L=HW G!1  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); YR\faVk  
httpConnection.setRequestProperty("User-Agent","NetFox"); l K{hVqpt  
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int responseCode=httpConnection.getResponseCode(); >a<.mU|#  
if(responseCode>=400) b}$+H/V
 
{ wq`s-qZu  
processErrorCode(responseCode); }^WdJd]P  
return -2; //-2 represent access is error RF$eQzW  
} d UE,U=  
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String sHeader; 5+0gR &|j  
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for(int i=1;;i++) l+K'beP  
{ h%na>G  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); tPWLg),  
//Utility.log(in.readLine());
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sHeader=httpConnection.getHeaderFieldKey(i); T3.&R#1M8-  
if(sHeader!=null) caR<Kb:;*  
{ ,$L4dF3  
if(sHeader.equals("Content-Length")) sjHE/qmq-Z  
{ aH(J,XY  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ,Q$q=E;X  
break; GTPHVp&y  
} F@7jx:tI  
} Vi
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else "m$##X\  
break; IZ-1c1   
} tyDU @M  
}
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catch(IOException e){e.printStackTrace ();}  RZ?jJm$  
catch(Exception e){e.printStackTrace ();} nIf1sH
>  
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}  
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Utility.log(nFileLength); se2!N:|R!G  
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return nFileLength; |-67\p]  
} <]t%8GB2V  
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//保存下载信息（文件指针位置） wo{gG?B  
private void write_nPos() qbN =
4  
{ \fLMr\LL&  
try{ \A#41  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Igt#V;kK"2  
output.writeInt(nStartPos.length); F`W?II?  
for(int i=0;i<nStartPos.length;i++) c9 eM/*:  
{ T@B/xAq5!  
// output.writeLong(nPos); U[-o> W#  
output.writeLong(fileSplitterFetch.nStartPos); x_Y!5yg E  
output.writeLong(fileSplitterFetch.nEndPos); H [\o RId  
} r.&Vw|*>  
output.close(); [#vH'y
  
} YQvD|x  
catch(IOException e){e.printStackTrace ();} V#$RR!X'  
catch(Exception e){e.printStackTrace ();} &-6Gc;f8  
} ;(Or`u]Dr  
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//读取保存的下载信息（文件指针位置） CAWN
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private void read_nPos() qS$Ox?Bw#u  
{ (NU NHxi5B  
try{ V!A~K   
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); `5.'_3  
int nCount = input.readInt(); prF%.(G2)  
nStartPos = new long[nCount]; =z69e%.  
nEndPos = new long[nCount]; `p-cSxR_  
for(int i=0;i<nStartPos.length;i++) %
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{ G`61~F
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nStartPos = input.readLong(); B
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nEndPos = input.readLong(); u'DRN,h+  
} E7UU  
input.close(); sf87$S0  
} 5coyr`7mP  
catch(IOException e){e.printStackTrace ();} i$G@R%  
catch(Exception e){e.printStackTrace ();} @o _}g !9=  
} zu{P#~21  
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private void processErrorCode(int nErrorCode) -;m0R  
{ q,|j]+
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System.err.println("Error Code : " + nErrorCode); l<LI7Z]A  
} AJ`h9%B  
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//停止文件下载 $ @`V  
public void siteStop() .j0$J\:i  
{ aP+X}r  
bStop = true; Be2DN5)  
for(int i=0;i<nStartPos.length;i++) .}TZxla0Zr  
fileSplitterFetch.splitterStop(); )'#A$ Fj  
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} ?mxMk6w  
} '8H
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//负责部分文件的抓取 q"8ea/  
**FileSplitterFetch.java Fj3a.'  
*/ /]Md~=yNp  
package NetFox; h2]P]@nW;W  
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import java.io.*; qiBVGH  
import java.net.*; :>f )g  
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public class FileSplitterFetch extends Thread { ,Uqs1#r  
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String sURL; //File URL C1n>M}b  
long nStartPos; //File Snippet Start Position D8?Vn"  
long nEndPos; //File Snippet End Position ,m|h<faZL
 
int nThreadID; //Thread's ID 'yEHI  
boolean bDownOver = false; //Downing is over LYK"(C  
boolean bStop = false; //Stop identical }!.(n=idZ  
FileAccessI fileAccessI = null; //File Access interface YZ8>OwQz2  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException (v
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{ /%1ON9o>  
this.sURL = sURL; 2-v%`fA  
this.nStartPos = nStart; !PQ<04jA!  
this.nEndPos = nEnd; y/7\?qfTk  
nThreadID = id; 8dIgjQX|  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 )}Kf
=  
} Js?]$V"  
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public void run() p]+Pkxz]'  
{ >@_^fw)  
while(nStartPos < nEndPos && !bStop) pO3SUOP  
{ 6 V=9M:  
rw JIx|(  
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try{ flbd0NB  
URL url = new URL(sURL); $G@5qxcV  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Wt-GjxGi  
httpConnection.setRequestProperty("User-Agent","NetFox"); bJTBjS-7  
String sProperty = "bytes="+nStartPos+"-"; iz PDd{[  
httpConnection.setRequestProperty("RANGE",sProperty); z$. 88^  
Utility.log(sProperty); K Z91-  
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InputStream input = httpConnection.getInputStream(); })Vi  
//logResponseHead(httpConnection); E*K;H8}s  
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byte[] b = new byte[1024]; =-n}[Y}A  
int nRead; nmKp[-5  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 9qzHS~l  
{ WW~sNC\3`(  
nStartPos += fileAccessI.write(b,0,nRead); Ai3*QX  
//if(nThreadID == 1) I,vJbvvl!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); c`w}|d]mC  
} ~=l;=7 T  
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Utility.log("Thread " + nThreadID + " is over!"); 4>e&f&y~  
bDownOver = true; c<Tf 2]vZE  
//nPos = fileAccessI.write (b,0,nRead); +#@I~u _}D  
} W.KDVE$}f  
catch(Exception e){e.printStackTrace ();} K1yzD6[eW  
} /@TF5]Ri  
} je=a/Y=%U{  
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//打印回应的头信息 yl+gL?IES  
public void logResponseHead(HttpURLConnection con) h J)h
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{ y _k l:Ssa  
for(int i=1;;i++) #c.K/&Gc7j  
{ E{P|)`,V  
String header=con.getHeaderFieldKey(i); w%jII{@,  
if(header!=null) Txb#C[`  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); kUrkG80q|  
Utility.log(header+" : "+con.getHeaderField(header)); j{+.tIzpq[  
else [/41%B2  
break; /"Uqa,{  
} R8Fv{7]c  
} #?- wm  
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public void splitterStop() $5%SNzzl  
{ ;+
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bStop = true; jasy<IqT!{  
} K`fuf=  
=$JET<(  
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} ')<hON44EX  
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/* r0% D58  
**FileAccess.java *#+An<iT ;  
*//文件访问(定位，写) z[qDkL  
package NetFox; |#R7wnE[k~  
import java.io.*; $Ri; ^pZw[  
_ZSR.w}j/  
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public class FileAccessI implements Serializable{ ":QZy8f9%  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 w@w(-F!%l  
RandomAccessFile oSavedFile; 8P&:_T!  
long nPos; |z^^.d~a0  
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public FileAccessI() throws IOException <*cikXS  
{ &`2)V;t  
this("",0); 8$Y9ORs4  
} A#YrWW  
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public FileAccessI(String sName,long nPos) throws IOException iSs:oH3l  
{ ri-b=|h2j  
oSavedFile = new RandomAccessFile(sName,"rw"); 1\I}2
;  
this.nPos = nPos; q9s=~d7  
oSavedFile.seek(nPos); Jij*x>K>y  
} T</F 0su|  
6?c7$Y  
!%%6dB@%t  
public synchronized int write(byte[] b,int nStart,int nLen) yEE*B:  
{ )bscBj@  
int n = -1; =U?dbSf1*  
try{ U z>+2m(  
oSavedFile.write(b,nStart,nLen); -m~#Bq  
n = nLen; u;2[AQ.  
} #!+:!_45  
catch(IOException e) 4 "'~NvO  
{ f9{Rb/l!BQ  
e.printStackTrace (); \z(gqkc 6  
} 1o{Mck  
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return n; -PR N:'T  
} {F.[&/A  
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} P@c5pc#|  
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/* c9h6C  
**SiteInfoBean.java zIAD9mQex  
*/ ;u)I\3`*!  
package NetFox; A2Gevj?F$  
[`7ThHX  
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public class SiteInfoBean { r*Ca}Z  
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private String sSiteURL; //Site's URL 9'bwWBf7  
private String sFilePath; //Saved File's Path A~70  
private String sFileName; //Saved File's Name U # qK.  
private int nSplitter; //Count of Splited Downloading File Ig>(m49d  
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public SiteInfoBean() =D"#U#>;7&  
{//nSplitter的缺省值为5 qlP
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//default value of nSplitter is 5 $(x]  
this("","","",5); )lDD\J7  
} },-H"Qs  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) b4N[)%@  
{ IW] rb/H  
sSiteURL= sURL; ' S/gmn  
sFilePath = sPath; pTLCWbF?  
sFileName = sName; Slc\&Eb  
this.nSplitter = nSpiltter; |P?*5xPB  
6(-N FnT  
; BHtCuY  
} R.<g3"Lm>  
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public String getSSiteURL() 7
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{ [ub e6  
return sSiteURL; sK?twg;D*|  
} ,r_Gf5c  
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public void setSSiteURL(String value) g*+>H1}  
{ O*P.]d  
sSiteURL = value; MkXmA`cP  
} 5wU]!bxr  
NL+N%2XG7  
#&e-|81H  
public String getSFilePath() 'i|YlMFIg  
{ ]u/sphPe  
return sFilePath; z},# ~L6$q  
} `r 4fm`<  
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public void setSFilePath(String value) deh*Ib:(S  
{ 4
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sFilePath = value; 4Ftu  
} QIFgQ0{  
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public String getSFileName() +R:(_:7  
{ {R{=+2K!|k  
return sFileName; EU Fa5C:  
} ]A_`0"m.U  
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public void setSFileName(String value) Bk{]g=DO  
{ -m
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sFileName = value; SUK?z!f<i  
} lPAQ3t!,  
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E2+`4g@{8<  
public int getNSplitter() %mgE;~"&  
{ %iqD5x$OA  
return nSplitter; Q22 GIr  
} +&H4m=D-#a  
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` 5>b:3  
public void setNSplitter(int nCount) +jgS
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{ hOK8(U0  
nSplitter = nCount; n~Lt\K:  
} ]T) 'Hb  
} _DEjF)S  
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7F.4Ga;  
/* .*Qx\,  
**Utility.java >^{yF~(  
*/ |;{6&S  
package NetFox; 7_[L o4_  
>=w)x,0yX  
2
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public class Utility { Yx`n:0  
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public Utility() `">=  
{ V0Hj8}l;M  
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} hgE71H\s  

akTk(  
//线程睡眠 1k^oS$UT  
public static void sleep(int nSecond) ?Q;=v~-Q  
{ 2st3  
try{ #Bw0,\  
Thread.sleep(nSecond); IdN41  
} U #0Cx-E  
catch(Exception e) 0PCGDLk8  
{ \z)%$#I  
e.printStackTrace (); JK]PRDyD  
} %@Jsal'  
} MnHNjsO#  
N6TH}~62}  
//日志 /g.U&oI]D  
public static void log(String sMsg) .fs3
>@T"#  
{ cidP|ie^  
System.err.println(sMsg); f%8C!W]Dm  
} "ocyK}l.?  
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"9807OME  
public static void log(int sMsg) D)}v@je"yP  
{ IAyp2  
System.err.println(sMsg); V]?R>qhgu  
} 5IpDeJ$  
} Zb#u0Tq  
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/zox$p$?h  
/* ` G kX  
**TestMethod.java {2gwk8  
*/ ,/U6[P_C5  
package NetFox; dD@(z:5M\  
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public class TestMethod { GKeU%x
 
4 H&#q>  
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public TestMethod() og>uj>H&  
{ ///xx/weblogic60b2_win.exe 4I(Xy]wm  
try{ CNx8] _2  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); e~(5%CO>#j  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); q0\6F^;M  
SiteFileFetch fileFetch = new SiteFileFetch(bean); P+HXn8@  
fileFetch.start(); 'we>q@  
} >C~6\L`c  
catch(Exception e){e.printStackTrace ();} bQ5\ ]5M  
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} I*^Ta{j[  
-DAlRz#d,  
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public static void main(String[] args) =?`c=z3~i$  
{ lUMdrt0@z  
new TestMethod(); q75
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} Yoll?_k+  
} x$(f7?s] 1  
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