http断点续传简单实现（java)

/* #j?SdQ  
**SiteFileFetch.java WCpCWtmy  
*/ L#}HeOEi[  
package NetFox; \@KKX  
import java.io.*; ] C&AU[U*  
import java.net.*; !VXs yH3r5  
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public class SiteFileFetch extends Thread { 4uV,$/  
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SiteInfoBean siteInfoBean = null; //文件信息Bean jO9w7u6  
long[] nStartPos; //开始位置 ku&m)'  
long[] nEndPos; //结束位置 T]fBVA  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Ug1[pONk  
long nFileLength; //文件长度 V|njgcn d  
boolean bFirst = true; //是否第一次取文件 dm+}nQI\  
boolean bStop = false; //停止标志 @#?w>38y  
File tmpFile; //文件下载的临时信息 5'mpd  
DataOutputStream output; //输出到文件的输出流 bY>JLRQJ-  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） O*:8gu'Y2  
public SiteFileFetch(SiteInfoBean bean) throws IOException |LwW/
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{ %dN',  
siteInfoBean = bean; :
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Q 6)5*o8n  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); L( B(x>w  
if(tmpFile.exists ()) (oiF05n h  
{ i=ztWKwKf  
bFirst = false; >,#73
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read_nPos(); KXS{@/"-B  
} P_Bhec|#fT  
else [&B}{6wry  
{
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nStartPos = new long[bean.getNSplitter()]; _Q $D6+  
nEndPos = new long[bean.getNSplitter()]; {;kH&Pp  
} :AzP3~BI  
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} 5V($|3PI  
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public void run() SjZ?keKZ  
{ S(b5Gj
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//获得文件长度 3o>.Z;  
//分割文件 |iJ+e -_R  
//实例FileSplitterFetch !8#!P  
//启动FileSplitterFetch线程 %mv9+WJN.  
//等待子线程返回 x,3oa_'E  
try{ qUMM}ls  
if(bFirst) Ijs"KAW ?  
{ u3Jsu=Nx-  
nFileLength = getFileSize(); +TR#  
if(nFileLength == -1) yU"'h[^  
{ ~Xf&<&5d T  
System.err.println("File Length is not known!"); HxgH*IMs  
} =u+.o<  
else if(nFileLength == -2) N-+`[8@(P<  
{ ~H0WHqcy  
System.err.println("File is not access!"); #f
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} z3lMD'uU3  
else w,CZ*/^  
{ g3i !>  
for(int i=0;i<nStartPos.length;i++) luEP5l2&  
{ 1 ^k#g,  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); *"%MT:  
} aJ"Tt>Y[.~  
for(int i=0;i<nEndPos.length-1;i++) -i}@o1o\  
{ *Y2d!9F}Sa  
nEndPos = nStartPos[i+1]; :e&P's=
 
} wF`9}9q  
nEndPos[nEndPos.length-1] = nFileLength; zg3q\~  
} KLc<c1BZ  
} P]pVYX#m  
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//启动子线程 rdL>yT/A  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; `B^HW8  
for(int i=0;i<nStartPos.length;i++) Ux2pqPb  
{ gda3{g7<)  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), u/@dWeY[]  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ~IB~>5U!  
nStartPos,nEndPos,i); (aO+7ykRuJ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .-:R mYGR  
fileSplitterFetch.start(); `GG PkTN  
} S"Q$ Ol"  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), KL4Z||n  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); /FZ@Z]Q0G  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", k($N_XlE  
nEndPos = " + nFileLength); TT(dCHft  
// fileSplitterFetch[nPos.length-1].start(); );$L#XpB  
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7@.UkBOx  
//等待子线程结束 <3!jra,h  
//int count = 0; )32BM+f"77  
//是否结束while循环 >,8DwNuq  
boolean breakWhile = false; #nL&x3  
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while(!bStop) S> f8j?n  
{ sQT0y(
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write_nPos(); A@@Z?t.  
Utility.sleep(500); Hm?zMyO.k  
breakWhile = true; j
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for(int i=0;i<nStartPos.length;i++) ak?XE4-N  
{ /lQGFLZL  
if(!fileSplitterFetch.bDownOver) 0<+=Ew5Z  
{ crJyk#_  
breakWhile = false; \pzqUTk  
break; CapWn~*g  
} O;qerE?i`  
} X9f!F2x  
if(breakWhile) ,R j{^-k  
break; *Mt's[8  
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//count++; ( _ZOUMe  
//if(count>4) [Hn4&PET  
// siteStop(); > dJvl|  
} 1)aB']K%  
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System.err.println("文件下载结束！"); zY<=r.m4  
} c}II
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catch(Exception e){e.printStackTrace ();} fPs'A  
} Ly?gpOqu5  
i
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//获得文件长度 /++CwRz@Gm  
public long getFileSize() -d+q+l>0  
{ Qwn/ ,  
int nFileLength = -1; 7_WD)Y2yS  
try{ v1yNVs\}  
URL url = new URL(siteInfoBean.getSSiteURL()); IYq)p /  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 'IweN  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'AX/?Srd  
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int responseCode=httpConnection.getResponseCode(); ?|8H|LBIr  
if(responseCode>=400) ^+
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{  _2VL%  
processErrorCode(responseCode); 3_W1)vd{
 
return -2; //-2 represent access is error %aU4d e^  
} 6mJa  
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String sHeader; Kb~s'cTxIO  
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for(int i=1;;i++) DUc -D==  
{ >A#wvQl7   
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); u/e-m/  
//Utility.log(in.readLine()); [XWY-q#Gg  
sHeader=httpConnection.getHeaderFieldKey(i); (&4aebkZO  
if(sHeader!=null) Lrgv:n  
{ lzz rzx^  
if(sHeader.equals("Content-Length")) +(iM]L$Fw%  
{ 12*'rU;*  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); AvdxDN  
break; P agzp%m  
} ]Cpd`}'  
} MP\$_;&xB  
else I"4j152P|  
break; " d3pkY  
} |:SBkM,  
} 1;<J] S$$  
catch(IOException e){e.printStackTrace ();} L+7j4:$B8  
catch(Exception e){e.printStackTrace ();} 0 !yvcviw  
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Utility.log(nFileLength); tuuc9H4B  
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return nFileLength; p#W[he  
} L;=:OX0  
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//保存下载信息（文件指针位置） TN}YRXtW+  
private void write_nPos() ]q DhGt  
{ [6Y6{
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try{ +2!J3{[J  
output = new DataOutputStream(new FileOutputStream(tmpFile)); [$_d|Z  
output.writeInt(nStartPos.length); D;.O#bS  
for(int i=0;i<nStartPos.length;i++) mw9;LNi\D  
{ z5PFppSQ  
// output.writeLong(nPos); J&w%lYiu5  
output.writeLong(fileSplitterFetch.nStartPos); K^bzZa+a  
output.writeLong(fileSplitterFetch.nEndPos); E]`)  
} h% BA,C  
output.close(); ;hi+.ng_  
} jA R@?X  
catch(IOException e){e.printStackTrace ();} hc}dS$=C  
catch(Exception e){e.printStackTrace ();} vh3Xd\N  
} d:C-   
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//读取保存的下载信息（文件指针位置） Q#8}p
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private void read_nPos() w}VS mt$F  
{ ,Ju

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try{ qepsR/0M  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); K2,oP )0.Y  
int nCount = input.readInt(); >|%m#JG  
nStartPos = new long[nCount]; =D.M}xqo  
nEndPos = new long[nCount]; t6&6kl  
for(int i=0;i<nStartPos.length;i++) #W,BUN}  
{ _sIhQ8$:  
nStartPos = input.readLong(); ab8uY.j  
nEndPos = input.readLong(); *[jG^w0z8~  
} ]Ln2|$R  
input.close(); y6ntGrZ}$  
} ^OKCvdS  
catch(IOException e){e.printStackTrace ();} <d~P
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catch(Exception e){e.printStackTrace ();} DytH} U"  
} ~TCz1UWV  
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private void processErrorCode(int nErrorCode) >=-w2&  
{ vwDnz/-  
System.err.println("Error Code : " + nErrorCode); k`Nc<nN8  
} l`8S1~j
 
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//停止文件下载 8qL*Nf  
public void siteStop() Xk%92Pto  
{ g#qt<d}j  
bStop = true; @ROMHMd}  
for(int i=0;i<nStartPos.length;i++) @0A7d $J(  
fileSplitterFetch.splitterStop(); @mBZu!,  
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} 44 ,:@  
} _#xS
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//负责部分文件的抓取 +c5z-X$^]  
**FileSplitterFetch.java <wUDcF  
*/ DK 4 8  
package NetFox; l<qK' P4  
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import java.io.*; o %s
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import java.net.*; q y7
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public class FileSplitterFetch extends Thread { <R
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String sURL; //File URL S05+G}[$  
long nStartPos; //File Snippet Start Position ?_q e 2R.  
long nEndPos; //File Snippet End Position `oP :F[B  
int nThreadID; //Thread's ID ]2\|<.  
boolean bDownOver = false; //Downing is over _]8FCO  
boolean bStop = false; //Stop identical ;n_|t/=  
FileAccessI fileAccessI = null; //File Access interface ,2T&3
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException x>vC;E${"  
{ |D<J9+  
this.sURL = sURL; (@*[^@ipV  
this.nStartPos = nStart;
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this.nEndPos = nEnd; uu L
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nThreadID = id; c'nEbelE  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /tI8JXcUK  
} O@r%G0Jge  
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public void run() dC8$Ql^<  
{ "!()yjy  
while(nStartPos < nEndPos && !bStop) oLK-~[p  
{ (`PgvBL:  
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try{ `Yn:fL7S  
URL url = new URL(sURL); m` ^o<V&  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (UWWULV  
httpConnection.setRequestProperty("User-Agent","NetFox"); }&A!h  
String sProperty = "bytes="+nStartPos+"-"; $5kb3x<W  
httpConnection.setRequestProperty("RANGE",sProperty); DXu915  
Utility.log(sProperty); 9x@( K|  
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InputStream input = httpConnection.getInputStream(); GlkTpX^b  
//logResponseHead(httpConnection); NrH2U Jm  
^
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byte[] b = new byte[1024]; -t~l!!N(  
int nRead; (os}s8cIh  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) +{U0PI82  
{ A\p'\@f  
nStartPos += fileAccessI.write(b,0,nRead); c,nE@~ul2  
//if(nThreadID == 1) Hx[YHu KL^  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ax$ashFO/!  
} E~vM$$O$  
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Utility.log("Thread " + nThreadID + " is over!"); o1C1F}gxU  
bDownOver = true; Ji4xor  
//nPos = fileAccessI.write (b,0,nRead); Cw7 07
 
} B1)gudP`  
catch(Exception e){e.printStackTrace ();} {3n|=  
} JDPn   
} n{sF'n</  
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;NNYJqWd^]  
//打印回应的头信息 uYVlF@]  
public void logResponseHead(HttpURLConnection con) CT5\8C  
{ l~P%mVC3m  
for(int i=1;;i++) IzVb  
{ 7\x7ySM  
String header=con.getHeaderFieldKey(i); ZlQ@k{Es~  
if(header!=null) ;f,`T  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Tbf't^O
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Utility.log(header+" : "+con.getHeaderField(header)); "B`k  
else o 4G%m>$  
break; ROcI.tL  
} FYPv:k  
} dr3j<D-Q  
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public void splitterStop() !p$HS0c  
{ y4sKe:@2  
bStop = true; }-YM>q  
} JSz;>  
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} b(^/WCykH  
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/* 2ZTz{|y  
**FileAccess.java Bgb~Tz'  
*//文件访问(定位，写) KnL-qc  
package NetFox; e4:,W+g,9  
import java.io.*; ay~c@RXW  
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public class FileAccessI implements Serializable{ ^h wF=  
9!'qLO  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 f</'=k  
RandomAccessFile oSavedFile; ]q!,onJ  
long nPos; RcJ.=?I!  
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public FileAccessI() throws IOException >]b>gc?3  
{ sVXIR  
this("",0); 9*fA:*T  
} q!UN<+k\h  
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public FileAccessI(String sName,long nPos) throws IOException +yC]f b  
{ X}jWNN  
oSavedFile = new RandomAccessFile(sName,"rw"); ]QM{aSvXA  
this.nPos = nPos; Iv,Ub_Ll9  
oSavedFile.seek(nPos); 2rxZN\gyL  
} LPuc&8lGWf  
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public synchronized int write(byte[] b,int nStart,int nLen) Ml-GAkgG  
{ *=G~26*!V  
int n = -1; \iN3/J4  
try{ Buxn!s  
oSavedFile.write(b,nStart,nLen); ?a)X)#lQ  
n = nLen; Mw{0A\6  
} ,orq&#*Wd  
catch(IOException e) kT7x !7C  
{ YoC{ t&rY  
e.printStackTrace (); Cn\5Vyrl  
} h>0R!Rl8  
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return n; |:qaF  
} Tt^PiaS!  
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} ;Gf,I1d}{  
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/* aC!e#(q  
**SiteInfoBean.java BH`%3Mw  
*/ ;i;2c
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package NetFox; ucP"<,a  
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public class SiteInfoBean { mBAI";L3  
aL)}S%5o?  
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private String sSiteURL; //Site's URL mZ%"""X\Ei  
private String sFilePath; //Saved File's Path NY(z
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private String sFileName; //Saved File's Name 5Q/&,NP  
private int nSplitter; //Count of Splited Downloading File !UzMuGj  
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public SiteInfoBean() ]TE(:]o7V  
{//nSplitter的缺省值为5 DJWm7 t  
//default value of nSplitter is 5 yW=I*f  
this("","","",5); ! .q,m>?+  
} wP|Amn+;  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) tVUC@M>'  
{ <bvbfS  
sSiteURL= sURL; 4z;@1nN_8a  
sFilePath = sPath; \zx &5a #  
sFileName = sName; {zckY  
this.nSplitter = nSpiltter; 4J~ZZ  
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} {4C/ZA{|l  
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public String getSSiteURL() \Fh#CI  
{ %pJRu-D  
return sSiteURL; q.}M^iDe  
} +VSq[P  
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public void setSSiteURL(String value) s^&Oh*SP*  
{ =/#+,  
sSiteURL = value; $.5f-vQp  
} c4Leh"
ry  
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public String getSFilePath() e=H,|)P  
{ 8h?):e  
return sFilePath; ~dtS  
} -%G}T}"_  
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public void setSFilePath(String value) DN X-\  
{ ZFxa2J~;  
sFilePath = value;  %"jp':  
} Yk^clCB{A(  
prdc}~J8{  

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public String getSFileName() \jpm   
{ _\ &N<  
return sFileName; .%"s| D  
} ahUc;S:v#  
}x~1w:zHd  

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public void setSFileName(String value) wCitQ0?  
{ NZQl#ZJH:  
sFileName = value; 2zPO3xL,  
} fep8hf B;  
fxOa(mt  
RxB9c(s^@  
public int getNSplitter() j3Yz=bsQ{c  
{ O{{\jn|lR  
return nSplitter; b%TLvV 9F  
} svWQk9d  
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S|Yz5)*  
public void setNSplitter(int nCount) vmGGdj5aI  
{ a W9_[#z5  
nSplitter = nCount; FhFP M)[  
} !uc"|S?  
} K\VL[HP-  
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/* X4$86  
**Utility.java 1 k\~%  
*/ uLq%Nu  
package NetFox; S2\|bs7;J,  
%2ZWSQD  
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public class Utility { *Rl
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q(s&2|  
public Utility() W }  
{ xsERnF>`  
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r^Mu`*x*  
} Ls2g#+  
*%aWGAu:  
//线程睡眠 Z[GeU>?P  
public static void sleep(int nSecond) 5<77o|  
{ KM9)  
try{ tPz!C&.=  
Thread.sleep(nSecond); 9NE
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} 40m>~I^q}  
catch(Exception e) -RBH5+SS2  
{ A>B_~=  
e.printStackTrace (); \1f&D!F]b  
} mGC!7^_D`  
} d+L!s7  
s;Sv@=\  
//日志 g+pj1ycw/  
public static void log(String sMsg) x*a^msY%  
{ 7\<}378/^  
System.err.println(sMsg); HlgkW&}c^  
} @3Nvf}He  
f}ES8Hh[  
+2 x|j>  
public static void log(int sMsg) :p0<AU47  
{ @w @SOzS)  
System.err.println(sMsg); %<rV~9:  
} %^LwLyoVM  
} w(cl,W/w  
cz.,QIt_  
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/* \Pt_5.bTs[  
**TestMethod.java P~9y}7Q\0  
*/ 'nP;IuMP  
package NetFox; PlC8&$
  
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jr3FDd]  
public class TestMethod { b75en{aDi*  
D"ecwx{%;C  
/=+Bc=<lZ  
public TestMethod() ,k+F8{Q.  
{ ///xx/weblogic60b2_win.exe R7NE=X4  
try{ -esq]c%3  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); x2$Y"b?vz  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); N}X7g0>hV  
SiteFileFetch fileFetch = new SiteFileFetch(bean); nmy!.0SQ-  
fileFetch.start(); jrLV\(p  
} y%@C-:
 
catch(Exception e){e.printStackTrace ();} 353*D%8  
%=<Kb\  
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} y#?AW`|  
n"|1A..^  
yl UkVr   
public static void main(String[] args) *jrQ-'<T  
{
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new TestMethod(); WOR H4h9  
}  zPW_  
} ! ~3zp L  
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