http断点续传简单实现（java)

/* h]VC<BD6S  
**SiteFileFetch.java QlH[_Pi  
*/ AD6 b  
package NetFox; r -uu`=,  
import java.io.*; D<*)^^  
import java.net.*; Q7mikg=1-  
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public class SiteFileFetch extends Thread { 'loko#6  
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SiteInfoBean siteInfoBean = null; //文件信息Bean =#&+w[4?&.  
long[] nStartPos; //开始位置 N)K
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long[] nEndPos; //结束位置 kn&BGYt  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 N[yS heT  
long nFileLength; //文件长度 Qv8 =CnuOT  
boolean bFirst = true; //是否第一次取文件 W{ZJ^QAq/  
boolean bStop = false; //停止标志 )E6E
}  
File tmpFile; //文件下载的临时信息 ^Q!A4qOQ  
DataOutputStream output; //输出到文件的输出流 &u(pBr8B  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） OY!WEP$F-C  
public SiteFileFetch(SiteInfoBean bean) throws IOException JbXi|OS/  
{ F C=N}5u  
siteInfoBean = bean; 9*r l7  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); e8z?) 4T  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); <DEu]-'>  
if(tmpFile.exists ()) 5R1?jlm  
{ *I k/Vu%;  
bFirst = false; |"eC0u  
read_nPos(); :G5O_T$  
} 5mm&l+N)  
else wV4MP1c$  
{ Nfmr5MU_  
nStartPos = new long[bean.getNSplitter()]; TEC#owz  
nEndPos = new long[bean.getNSplitter()]; }rWg']  
} DMKtTt[}  
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} F-D$Y?m  

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public void run() [X@JH6U r  
{ t ^1uj:vD  
//获得文件长度 +zl[C  
//分割文件 xb&,9Lxd|  
//实例FileSplitterFetch 5BM6Pnle  
//启动FileSplitterFetch线程 q3
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//等待子线程返回 ,lb}&uZo  
try{ ]Z[0xs  
if(bFirst) !H6X%hlk  
{ bj?=\u  
nFileLength = getFileSize(); <J.q[fd1*  
if(nFileLength == -1) (Hs,Tj  
{ 'GLpSWL+*  
System.err.println("File Length is not known!"); QEF$Jx  
} (!9+QXb'  
else if(nFileLength == -2) `9
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{ H9WXp&  
System.err.println("File is not access!"); e&NJj:Ph*  
} GX*9R>  
else r<Q0zKW!jN  
{ pK0@H"$8  
for(int i=0;i<nStartPos.length;i++) LFvZ 7M\\  
{ 9)4_@rf%  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); jQ-2SA O  
} +Y>oNX1KN  
for(int i=0;i<nEndPos.length-1;i++) ]y"=/Nu-Ja  
{ .P ??N  
nEndPos = nStartPos[i+1]; 8,&Y\b`..  
}
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nEndPos[nEndPos.length-1] = nFileLength; |vxmgX)  
} bfK4ps}m*  
} .k|\xR  
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//启动子线程 Fn{Pmo*rs  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; lZ) qV!<  
for(int i=0;i<nStartPos.length;i++) U7-*]i
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{ f#gV>.P;h\  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2_)gJ_kP  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), @H}Hjg_>m  
nStartPos,nEndPos,i); ?^`fPH=  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); dKa2_|k'  
fileSplitterFetch.start(); r5NH*\Q  
} }$(\,SzW  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Fj"/jdM  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); pfFHuS~  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", |ZOdfr4uW  
nEndPos = " + nFileLength); 9xFI%UOb#  
// fileSplitterFetch[nPos.length-1].start(); t~8H~%T>v  
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+ 7wMM#z  
//等待子线程结束 p+b$jKWQ  
//int count = 0; Q2* ~9QkU  
//是否结束while循环 SEH[6W3  
boolean breakWhile = false; goJ'z|))  
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while(!bStop) .-Dc%ap
]  
{ al7D3J  
write_nPos(); >qd=lm <,  
Utility.sleep(500); @\W-=YKLg  
breakWhile = true; NnaO!QW%  
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for(int i=0;i<nStartPos.length;i++) Ns5P,[pBOZ  
{ -x|!?u5F  
if(!fileSplitterFetch.bDownOver) K\.tR  
{ A,3qjd,$ c  
breakWhile = false; i>dFpJ  
break; E5Sn mxd  
} p+y"r4  
} ?F*I2rt#  
if(breakWhile) %al 5 {  
break; S27s Rxfr  
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//count++;  {@k , e  
//if(count>4) > }kZXeR|  
// siteStop(); [8K :ml  
} Sf@xP.d  
;WhRDmT  
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System.err.println("文件下载结束！"); (^E5y,H<g  
} G#A6<e/  
catch(Exception e){e.printStackTrace ();} 3{wuifS  
} MZ~N}y  
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//获得文件长度 XWq"_$&LF  
public long getFileSize() d1'= \PYr  
{ 5hTScnL%  
int nFileLength = -1; `7[!bCl  
try{ $9:  @M.  
URL url = new URL(siteInfoBean.getSSiteURL()); O2"V'(  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ln8es{q  
httpConnection.setRequestProperty("User-Agent","NetFox"); %,zHS?)l  
r|i)  
^dE[ ;  
int responseCode=httpConnection.getResponseCode(); >qmNT/  
if(responseCode>=400) G\^<MR|  
{ O- LwX >  
processErrorCode(responseCode); pgZQ>%  
return -2; //-2 represent access is error QS1lg  
} ($W%&(:/  
}>V
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String sHeader; hTmJ ~m'J  
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for(int i=1;;i++) f.uy;v  
{ O\)Kg2  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); H({m1v ~R  
//Utility.log(in.readLine()); <FI
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sHeader=httpConnection.getHeaderFieldKey(i); IreY8.FND  
if(sHeader!=null) gyhy0  
{ dczSW]%  
if(sHeader.equals("Content-Length")) ]Tg@wMgI  
{ 2 )3oX  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ,t:P  
break; Ge7B%p8  
} W1Ye+vg/s  
} ,+I]\ZeO  
else %s^1de  
break; G;EJ\J6@Yw  
} 23 #JmR  
} t*H|*L#YR  
catch(IOException e){e.printStackTrace ();} -Q&@P3
x  
catch(Exception e){e.printStackTrace ();} S4-jFD)U  
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Utility.log(nFileLength); '2|P-/jU  
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return nFileLength;  yK$aVK"  
} b#R$P]dr=  
pS}IU{#;  
~tZB1+%)  
//保存下载信息（文件指针位置） dnQ6Ras  
private void write_nPos() sg49a9`8  
{ leI ]zDk=  
try{ %~8f0B|im  
output = new DataOutputStream(new FileOutputStream(tmpFile)); S?J(VJqE  
output.writeInt(nStartPos.length); pZ3sp!  
for(int i=0;i<nStartPos.length;i++) T<NOLfk66  
{ `AvK=]  
// output.writeLong(nPos); G6G-qqXy6  
output.writeLong(fileSplitterFetch.nStartPos); ]qu6/Z  
output.writeLong(fileSplitterFetch.nEndPos); 65*Hf3~~  
} w{So(AF  
output.close(); Q1rEUbvCE  
} NL;sn"  
catch(IOException e){e.printStackTrace ();} `H$=hr  
catch(Exception e){e.printStackTrace ();} n&zEYCSI  
} _`p^B%[  
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//读取保存的下载信息（文件指针位置） ^S?f"''y3  
private void read_nPos() tE <?L  
{ Ei\>gXTH1-  
try{ l&:8 'k+%=  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); c_?^:xs:d  
int nCount = input.readInt(); ,2+d+Zuh  
nStartPos = new long[nCount]; -Fu,oEj{*  
nEndPos = new long[nCount]; kM&-t&7  
for(int i=0;i<nStartPos.length;i++) $5&~gHc,  
{ "*N#-=MJF  
nStartPos = input.readLong(); $#2<f 6  
nEndPos = input.readLong(); 56.JBBZZ  
} "Z;({a$v  
input.close(); -$I30.#  
} |@yYM-;6  
catch(IOException e){e.printStackTrace ();} 8{ =ha  
catch(Exception e){e.printStackTrace ();} aDxNAfP  
} AXSip  
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private void processErrorCode(int nErrorCode) \ym^~ Q|  
{ MX7Ix{  
System.err.println("Error Code : " + nErrorCode); \Q1&w2mw  
} q9{)nU  
!!)$?R;1  
,4 _H{+M  
//停止文件下载 m<kJH<!j  
public void siteStop() V2M4g  
{ 1 A0BM  
bStop = true; a?8)47)  
for(int i=0;i<nStartPos.length;i++) v+`'%E  
fileSplitterFetch.splitterStop(); R5((
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}4H}*P>+  
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} 
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} aR('u:@jHi  
//负责部分文件的抓取 -)3+/4Q(  
**FileSplitterFetch.java bZ OCj1  
*/ -1d*zySL  
package NetFox; o?t
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import java.io.*; gsM^Pu09ud  
import java.net.*; |G$-5 7fk  
sPeTW*HeR  
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public class FileSplitterFetch extends Thread { rqdN%=C  
vNuws_  
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String sURL; //File URL EG$-D@o\I  
long nStartPos; //File Snippet Start Position (_>SuQK  
long nEndPos; //File Snippet End Position >/Q^.hzd  
int nThreadID; //Thread's ID rKI<!  
boolean bDownOver = false; //Downing is over ;' vkF  
boolean bStop = false; //Stop identical 2nCc(F&+?
 
FileAccessI fileAccessI = null; //File Access interface i8-Y,&>V  
G/~gF7  
% XZ&(  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException /IJy'@B  
{ %6 GM[1__  
this.sURL = sURL; *AGf'+j*z  
this.nStartPos = nStart; 9#&H'mG  
this.nEndPos = nEnd; GiEt;8  
nThreadID = id; As,e.V5!  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Ut;4`>T  
} |UMm>.\'  
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]&q<O0^'  
public void run() \4G9YK-N>  
{ (l-=/6-  
while(nStartPos < nEndPos && !bStop) Zl3e=sg=  
{ ~yw]<{?  
~LV]cX2J(  
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try{ Q1x&Zm1v  
URL url = new URL(sURL); Lw_|o[I}  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); " M?dU^U^  
httpConnection.setRequestProperty("User-Agent","NetFox"); udA@9a^;  
String sProperty = "bytes="+nStartPos+"-"; 4 l-UrnZ  
httpConnection.setRequestProperty("RANGE",sProperty); Tq?Ai_  
Utility.log(sProperty); qTdwi?j_  
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InputStream input = httpConnection.getInputStream(); -)')PV_+  
//logResponseHead(httpConnection); 0zSz[;A  
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byte[] b = new byte[1024]; 0;">ETh=  
int nRead; at@tS>Dv  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) R#;xBBt8  
{ (B\ UZb  
nStartPos += fileAccessI.write(b,0,nRead); ~h Dp-R;  
//if(nThreadID == 1) aEIz,^3  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); JJ_Z{  
} ~S;-sxoO0l  
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E&y)`>Nq{  
Utility.log("Thread " + nThreadID + " is over!"); jI*@&3  
bDownOver = true; wS
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//nPos = fileAccessI.write (b,0,nRead); 6fo"k+S  
} w(S~}'Sg*P  
catch(Exception e){e.printStackTrace ();} iCg%$h  
} e"eIQI|N  
}
:}Yk0*  
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//打印回应的头信息 Y)5O %@Rl  
public void logResponseHead(HttpURLConnection con) la-:"gKC  
{ *!&?Xy%\"j  
for(int i=1;;i++) ,pGA|ob  
{ 4}/gV)  
String header=con.getHeaderFieldKey(i); f)z(9JJL  
if(header!=null) EwFq1~  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); `P !idg*  
Utility.log(header+" : "+con.getHeaderField(header)); pInEB6L.P  
else NFEr
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break; iz`>'wpC  
} hB.8\-}QMq  
} #\m.3!Hcr  
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public void splitterStop() {x,)OgK!{  
{ 3Q=\W<Wu  
bStop = true; .9B@w+=6  
} 0,DrVGa  
} f&=}  
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} ,;w~ VZ4  
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g*YA~J@  
/* nf"#F@dk  
**FileAccess.java +<[q"3
  
*//文件访问(定位，写) uE9,N$\L_  
package NetFox; 7R:Ij[dV  
import java.io.*; a<r,LE  
ez[x8M>  
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public class FileAccessI implements Serializable{ a7ZufB/  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 @XzfuuE]  
RandomAccessFile oSavedFile; k@|px#kq  
long nPos; SQ2v  
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public FileAccessI() throws IOException @U5gxK*  
{ qQ3Q4R\  
this("",0);
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} ;2
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public FileAccessI(String sName,long nPos) throws IOException 8o%Vn'^t  
{ {X(nn.GpC  
oSavedFile = new RandomAccessFile(sName,"rw"); v8yC
f7+"  
this.nPos = nPos; {*GBUv5  
oSavedFile.seek(nPos); _h}(jEd!  
} *m<[ sS  
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6&SNFOX{@  
public synchronized int write(byte[] b,int nStart,int nLen) zytN leyc  
{ \z!lw  
int n = -1; `IwZVz  
try{ ~//9Nz~;3  
oSavedFile.write(b,nStart,nLen); l%GArH`  
n = nLen; ~$T>,^K y  
} aQx6;PC  
catch(IOException e) /Ls|'2J<$  
{ k $^/$N  
e.printStackTrace (); TU~y;:OJ  
} mp$IhJ6#  
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return n; ^lV}![do!  
} `f~bnL  
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# f-hI  
} G2I%^.s  
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/*
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**SiteInfoBean.java O[MFp  
*/ RNB&!NC  
package NetFox; }9\6!GY0  
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public class SiteInfoBean { C;JW\J~W  
#btf|\D  
9;7"S.7AV  
private String sSiteURL; //Site's URL @B>D>B  
private String sFilePath; //Saved File's Path 7_s+7x =  
private String sFileName; //Saved File's Name B(s^(__]  
private int nSplitter; //Count of Splited Downloading File d"-I^|[OM  
Ff/Ap&0+  
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>  
public SiteInfoBean() >>KI_$V  
{//nSplitter的缺省值为5 )GG9
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//default value of nSplitter is 5 Y2l;NSWU  
this("","","",5); 8o|C43Q_  
} ;AOLbmb)H4  
=bD.5,F)  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) nsi?.c&0!  
{ OjlX<y.  
sSiteURL= sURL; |-S!)iG1V  
sFilePath = sPath; *> nOL  
sFileName = sName; bskoi;)u  
this.nSplitter = nSpiltter; p#P<V%  
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} LhAW|];  
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public String getSSiteURL() N(4y}-w$  
{ 
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return sSiteURL; JGvhw,g  
} 3;Yd"  
%p)&mYK{  
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public void setSSiteURL(String value) gkx
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{ *l =f=  
sSiteURL = value; \f4rA
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} 4bL *7
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public String getSFilePath() 9rz$c, Y(  
{ 'q:7PkN!p  
return sFilePath; LRu*%3xx  
} yKj}l,i~8  
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public void setSFilePath(String value) /Lr`Aka5  
{ {c3FJ5:  
sFilePath = value; /Q7q2Ne^*  
} aG;F=e  
H:hM(m0?q  
Dmi.@.  
public String getSFileName() ZHZxr  
{ , 2#Q>  
return sFileName; l9|K,YVW  
} zT)cg$8%fY  
.>TG{>sH  
Ua|iAD1  
public void setSFileName(String value) :X}SuM?c  
{ S{l)hwlE  
sFileName = value; Q.Nw#r+m  
} :atd_6   
o[KZm17  
:t`W&z41  
public int getNSplitter() oZ/"^5  
{ GO2q"a  
return nSplitter; Pi5MFw'v  
} !\{2s!l~  
r3' DXP  
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public void setNSplitter(int nCount) Xux[  
{ |(Wwh$  
nSplitter = nCount; *V:U\
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} XZ.D<T"  
} iP9]b&  
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6p)&}m9!  
/* J/Y9X,  
**Utility.java 5
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*/ PCaFG;}  
package NetFox; L`<#vi  
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46)[F0,$r  
public class Utility { +Eb-|dM  
*LBF+L^C%  
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public Utility() \9p.I?=  
{ [I%
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} T2]8w1l&K  
.?g=mh79(  
//线程睡眠 ku*k+4rz  
public static void sleep(int nSecond) qk'&:A  
{ Y1r'\@L w  
try{ vA:ZR=)F  
Thread.sleep(nSecond); [>GblL  
} ]aMDx>OE  
catch(Exception e) Jgr;'U$  
{ feB 
?  
e.printStackTrace (); 5s^vC2$)  
} B0yGr\KJ  
} .
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}OcrA/  
//日志 S6bYd`  
public static void log(String sMsg) <HJLs+C  
{ ^pe/~ :a  
System.err.println(sMsg); 8d'/w}GV  
} rN#9p+t$  
3
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X$ul=iBs  
public static void log(int sMsg) @ ^F{  
{ kb~ s,@p  
System.err.println(sMsg); Oz\J+  
} rC|nE=i  
} Ag:/iB]  
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E%E`\mFD  
/* "&D0Sd@[?  
**TestMethod.java |wb_im  
*/ H&*&n}vh5y  
package NetFox; I&15[:b=-  
}vB{6E+h/w  
)ZLj2H<  
public class TestMethod { g$)0E<  
_+)
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public TestMethod() n3V$Xtxw  
{ ///xx/weblogic60b2_win.exe M-Vz$D/aed  
try{ R$}Hv  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); @~$=96^  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); {c?{M.R  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ^|h_[>  
fileFetch.start(); 2.);OFk+  
} 7?k3jDK  
catch(Exception e){e.printStackTrace ();} W=S^t_F  
^oC>,%7  
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} j3w~2q"r  
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public static void main(String[] args) $ta"Ug.z  
{ Z[z" v  
new TestMethod(); kd&~_=Q  
} #]i^L;u1A  
} jZ5ac=D&I  
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