http断点续传简单实现（java)

/* mOYXd,xd  
**SiteFileFetch.java -ktYS(8&  
*/ Gs}lw'pK  
package NetFox; jg3['hTJT  
import java.io.*; a\I`:RO=<Z  
import java.net.*; y"nCT3  
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public class SiteFileFetch extends Thread { UX'tdB !A  
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SiteInfoBean siteInfoBean = null; //文件信息Bean @;d7#!:cE  
long[] nStartPos; //开始位置 NMP*q @  
long[] nEndPos; //结束位置 /bqJ6$  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 @(rLn  
long nFileLength; //文件长度 rX&?Xi1JeV  
boolean bFirst = true; //是否第一次取文件 `P9%[8`C 9  
boolean bStop = false; //停止标志 sY'd
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File tmpFile; //文件下载的临时信息 ;WL0  
DataOutputStream output; //输出到文件的输出流 5d82Ms  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） {|@N~c+  
public SiteFileFetch(SiteInfoBean bean) throws IOException Wy$Q!R=i  
{ 5{8,+ Z  
siteInfoBean = bean; 5cl%>U  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); d _koF-7  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); fP1fm  
if(tmpFile.exists ()) mDU-;3OqF  
{ q
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bFirst = false; *(<3 oIRS  
read_nPos(); dtq]_HvTJ  
} yAVt[+0  
else vy F(k3W  
{ UIw6~a3E  
nStartPos = new long[bean.getNSplitter()];  eYRm:KC  
nEndPos = new long[bean.getNSplitter()]; YA^g[,  
} ,[Z;"wE  
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} q]t^6m&-  
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public void run() & |o V\L  
{ -3:x(^|:K  
//获得文件长度 YcBAW4B`  
//分割文件 fBt7#Tc=U  
//实例FileSplitterFetch j-etEWOTr  
//启动FileSplitterFetch线程 GEi^3UD  
//等待子线程返回 &rxR"^x\  
try{ Rd*/J~TK  
if(bFirst) 38
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{ Cqk6Igw  
nFileLength = getFileSize(); LIHf]+  
if(nFileLength == -1) o>Z+=&BZ@a  
{ $(%t^8{a~G  
System.err.println("File Length is not known!"); P(Hh%
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} ZCVN+::Y  
else if(nFileLength == -2) bpeWK&  
{ _Msaub!N  
System.err.println("File is not access!"); \Tj(]  
} bga2{<VF  
else :dzamHbX9  
{ -n~VMLd?@  
for(int i=0;i<nStartPos.length;i++) 1{S" axSL  
{ K&noA  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); b}r3x&)  
} ~UJ_Rr54  
for(int i=0;i<nEndPos.length-1;i++) KcjP39@I  
{ I*K~GXWs#  
nEndPos = nStartPos[i+1]; DavG=kvd  
} th*E"@  
nEndPos[nEndPos.length-1] = nFileLength; JEes'H}Y  
} z '%Vy  
} ?5 d3k%  
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//启动子线程 WChJ <[]W  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; D*j\g
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for(int i=0;i<nStartPos.length;i++) QRv2%^L  
{ r yO\$m  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6y9#am?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ToVm]zPOUt  
nStartPos,nEndPos,i); : LI*#~'Ka  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); vQ}llA h  
fileSplitterFetch.start(); w#,C{6  
} rB:W
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), b fsTeW+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ,9p 4(jjX  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", p`JD8c  
nEndPos = " + nFileLength); jM90 gPX>,  
// fileSplitterFetch[nPos.length-1].start(); y(8AxsROp  
f+huhJS5e  
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//等待子线程结束 `=Hh5;ep  
//int count = 0; y85/qg)H^  
//是否结束while循环 #SRGVa`x  
boolean breakWhile = false; K_B-KK(^  
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while(!bStop) /wL}
+  
{ \6xVIQ& 0  
write_nPos(); v7/qJ9l  
Utility.sleep(500); e? fFh,a  
breakWhile = true; ~V"D|U;i +  
.~6p/fHX  
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for(int i=0;i<nStartPos.length;i++) |L4K#  
{ :- ydsR/  
if(!fileSplitterFetch.bDownOver) _S#uxgL<  
{ }4kd=]Nk  
breakWhile = false; 1G+42>?<1  
break; Ed)t87E  
} ><[($Gq`g  
} n-{G19?  
if(breakWhile) p/xxoU  
break; Nq)=E[$  
n||/3-HDj  
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//count++; =x~HcsJ8!R  
//if(count>4) +)FB[/pXk  
// siteStop(); W9?Vh{w  
} T'l >$6  
{ls$#a+d  
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System.err.println("文件下载结束！"); &/4W1=>(  
} V3-5:z  
catch(Exception e){e.printStackTrace ();} /4]M*ls  
} QOkPliX  
m-UI^M,@<  
[dL4u^]{  
//获得文件长度 :0j9  
public long getFileSize() 2*5Z| 3aX  
{ >v`lsCGb  
int nFileLength = -1; |b52JF ",  
try{ `X
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URL url = new URL(siteInfoBean.getSSiteURL()); e@6<mir[4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Mjrl KI}f/  
httpConnection.setRequestProperty("User-Agent","NetFox"); $z]gy]F  
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int responseCode=httpConnection.getResponseCode(); g&H6~ +\
 
if(responseCode>=400) `6b!W0$ -  
{ }r6SV%]:  
processErrorCode(responseCode); HP2]b?C  
return -2; //-2 represent access is error #m6 eG&a  
} _U)DL=a'  
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String sHeader; h84}lxT^]  
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for(int i=1;;i++) PWOV~`^;  
{ z1?7}9~`0c  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 6';'pHqe  
//Utility.log(in.readLine()); )%U&z>^P  
sHeader=httpConnection.getHeaderFieldKey(i); 9Nglt3J
[  
if(sHeader!=null) <1VzQH!o  
{ 1_THBL26d  
if(sHeader.equals("Content-Length")) %<JjftNQ  
{ P7(+{d{  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); JG
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break; &+=A;Y)  
} EUU9JnQhBJ  
} n3-u.Fb  
else PBb@J'b  
break; >n)N=Zyu  
} V4}9f5FR  
} RX%*:lXi_  
catch(IOException e){e.printStackTrace ();} !MNUp(:  
catch(Exception e){e.printStackTrace ();} w%)=`'s_  
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Utility.log(nFileLength); iVzv/Lqm1  
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return nFileLength; 2P~zYdjS  
} M;={]w@n  
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//保存下载信息（文件指针位置）  z@^l1)m  
private void write_nPos() 0m6Vf x  
{ Ps(3X@  
try{ CE:TQzg  
output = new DataOutputStream(new FileOutputStream(tmpFile)); *[(O&L&0  
output.writeInt(nStartPos.length); fP%hr gL  
for(int i=0;i<nStartPos.length;i++) >Qz#;HI
 
{ $ckX H,l_  
// output.writeLong(nPos); 1g5%Gr/0$5  
output.writeLong(fileSplitterFetch.nStartPos); 'H<?K  
output.writeLong(fileSplitterFetch.nEndPos); @;M( oFS9  
} 9~bje^M  
output.close(); g= k}6"F~  
} i2/:' i  
catch(IOException e){e.printStackTrace ();} Zh]d&Xeq  
catch(Exception e){e.printStackTrace ();} Glcl7f"<^  
} &xM
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//读取保存的下载信息（文件指针位置） h #Od tc1)  
private void read_nPos() 7-.YVM~R  
{ ?N<* ATCL  
try{ 6]rIYc[,  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); *<#jr  
int nCount = input.readInt(); 11}X2j~Ww  
nStartPos = new long[nCount]; W~k"`g7uu  
nEndPos = new long[nCount]; MQY^#N  
for(int i=0;i<nStartPos.length;i++) L"A,7@:Vd  
{ NduvfA4  
nStartPos = input.readLong(); RxY ;'NY  
nEndPos = input.readLong(); -mOSB(#bo  
} A9ia[2[  
input.close(); wG
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} T>e!DOW;  
catch(IOException e){e.printStackTrace ();} =0TnH<`  
catch(Exception e){e.printStackTrace ();} mS5'q q;t  
} DcE)6z#  
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private void processErrorCode(int nErrorCode) %+YLe-\?  
{ O&Q_vY  
System.err.println("Error Code : " + nErrorCode); N^pTj<M<g  
} OACRw%J:X{  
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//停止文件下载 os|8/[gT  
public void siteStop() "qjkwf)\  
{ at
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bStop = true; >{p&_u.r-  
for(int i=0;i<nStartPos.length;i++) P%
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fileSplitterFetch.splitterStop(); I?LJXo\O  
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} B*p`e1  
} \:9dt8(-U  
//负责部分文件的抓取 0m7ANqE[Z  
**FileSplitterFetch.java wv>*g:El'  
*/ zD:"O4ZM^^  
package NetFox; O-y/K2MC*  
k'E3{8<!  
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import java.io.*; %yX?4T;b  
import java.net.*; 'd4I/  
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public class FileSplitterFetch extends Thread { rXc-V},az8  
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String sURL; //File URL ~A2{$C  
long nStartPos; //File Snippet Start Position \B) a57  
long nEndPos; //File Snippet End Position r:lv[/D  
int nThreadID; //Thread's ID iz!E1(z(  
boolean bDownOver = false; //Downing is over B/.+&AJw  
boolean bStop = false; //Stop identical A&X(\c M  
FileAccessI fileAccessI = null; //File Access interface EjW3_ %  
sS(t }$  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException =(:{>tO_"  
{ (? j $n?p  
this.sURL = sURL; =NLsT.aa  
this.nStartPos = nStart; gcDo o2RE  
this.nEndPos = nEnd; nf=*KS\v  
nThreadID = id; a3D''Ra  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ef8_w6i  
} .'N:]G@!  
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public void run() 07 [%RG  
{ |^9+c2  
while(nStartPos < nEndPos && !bStop) 5Z"IM8
?  
{ G<n(\85X  
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try{ vFKX@wV S  
URL url = new URL(sURL); /{@^
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); </! `m8\  
httpConnection.setRequestProperty("User-Agent","NetFox"); ^f*}]`S  
String sProperty = "bytes="+nStartPos+"-"; 1{D_30sG.  
httpConnection.setRequestProperty("RANGE",sProperty); M &`ZF  
Utility.log(sProperty); eD5:0;X2  
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InputStream input = httpConnection.getInputStream(); W[Kv Qt3%  
//logResponseHead(httpConnection); )c|S)iJ7=z  
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I3sH8/*  
byte[] b = new byte[1024]; gwVfiXR4  
int nRead; wM
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) n[DQ5l
  
{ :'1UX <&B  
nStartPos += fileAccessI.write(b,0,nRead); l{q$[/J~)  
//if(nThreadID == 1) W=b<"z]RE  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [O~'\Q  
} #m>Rt~(,S  
:lf;CT6$  
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Utility.log("Thread " + nThreadID + " is over!"); ~DY5`jV  
bDownOver = true; /tIR}qK  
//nPos = fileAccessI.write (b,0,nRead); YdsY2  
} LF o{,%B  
catch(Exception e){e.printStackTrace ();} '2)c;/-E  
} DXX(qk)6  
} xW|^2k  
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//打印回应的头信息 P(iZGOKUs=  
public void logResponseHead(HttpURLConnection con) CbPCj.MH  
{ 0LI:R'P+P[  
for(int i=1;;i++) 2K >tI9);  
{ F:$Dz?F0v  
String header=con.getHeaderFieldKey(i); 'zYKG5A  
if(header!=null) "V/|RC  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); j5hM|\]  
Utility.log(header+" : "+con.getHeaderField(header)); Mou@G3  
else 6 0C;J!D  
break; :CH*~o  
} \1`L-lz  
} e|Ip7`  
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public void splitterStop() dFdll3bC  
{ }mGOEG|F2  
bStop = true; e<_yr>9g"  
} JtB"Dh  
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} ZHPsGHA  
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/* RX]x3-  
**FileAccess.java G`!ff  
*//文件访问(定位，写) _W@SCV)yH  
package NetFox; *7L*:g  
import java.io.*; OBF3)L]  
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public class FileAccessI implements Serializable{ c k~gB  
8 I'1~d%$  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 XTIRY4{ d  
RandomAccessFile oSavedFile; lHYu-}TNP  
long nPos; ~&E|;\G  
"|1MJuY_6  
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public FileAccessI() throws IOException Effp^7 3  
{ m7:E73:  
this("",0); Salu[)+?  
} [\9
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public FileAccessI(String sName,long nPos) throws IOException wp/u*g  
{ 4fDo}~  
oSavedFile = new RandomAccessFile(sName,"rw"); 'pE %'8R  
this.nPos = nPos; )B d`N^k+  
oSavedFile.seek(nPos); FV[6">;
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} 1'|6IR1'  
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public synchronized int write(byte[] b,int nStart,int nLen) 47Y|1  
{ Q37VhScs  
int n = -1; K#"@nVWJ.m  
try{ eO,  
oSavedFile.write(b,nStart,nLen); /)80@  
n = nLen; ] =Js5  
} //--r5Q  
catch(IOException e) {$iJYS\  
{ (xU+Y1*g"%  
e.printStackTrace (); k&nhF
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} _ Ko
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return n; l<<G".?  
} 1B3,lYBM  
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} i'!M<>7  
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/* O$ i6r]j_  
**SiteInfoBean.java ;(w=}s%]+  
*/ `w Sg/  
package NetFox; ";~}"Yz?[  
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public class SiteInfoBean { BfOG e!Si  
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private String sSiteURL; //Site's URL $"{V],:T |  
private String sFilePath; //Saved File's Path ADX}  
private String sFileName; //Saved File's Name XA])<dZ  
private int nSplitter; //Count of Splited Downloading File TGLkwXOkT  
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public SiteInfoBean() S&-sl
  
{//nSplitter的缺省值为5 TJY$<:  
//default value of nSplitter is 5 MW9B -x  
this("","","",5); ,IUMH]D  
} U]sU b3  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter)
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{ |xzqYu?o  
sSiteURL= sURL; +!POKr  
sFilePath = sPath; 6,G^iv6H  
sFileName = sName; 5q]
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this.nSplitter = nSpiltter; {s8''+Q#(-  
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} pmCBe6n\l  
i/
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public String getSSiteURL() nGW wXySq  
{ if5Y!Tx?G  
return sSiteURL; z@y* jT  
} $#4z>~0  
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public void setSSiteURL(String value) LWbWj ^  
{ MC#bo{Bq3-  
sSiteURL = value; |iM*}Ix-  
} E08AZOY&g  
B4R,[WE"  

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public String getSFilePath() e;3$7$n Pv  
{ Lu:!vTRmw  
return sFilePath; \)BKuIP  
} @=wAk5[IN  
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8zj09T[  
public void setSFilePath(String value) l^`!:BOtR  
{ k9 *0xukJ  
sFilePath = value;
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} `?JrC3  
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public String getSFileName() uy\YJ.WMQ  
{ [9?=&O#*  
return sFileName; {OAy@6 +  
} f| N(~  
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public void setSFileName(String value) =As'vt 0  
{ *C\4%l   
sFileName = value; cJ8*[H<NV  
} 6C]!>i}U  
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public int getNSplitter() r)j#Skh].  
{ R:.7c(s  
return nSplitter; ^\+6*YE 4  
} I:6xDDpZG`  
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public void setNSplitter(int nCount) M2xUs  
{ 3al5Vu2:  
nSplitter = nCount; j|aT`UH03  
} }4 $EN  
} -nk%He  
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/* *Mp<4B  
**Utility.java BK /;HG  
*/ v>R.M"f  
package NetFox; V)(pe #P  
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public class Utility { %ANPv=  
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public Utility() 9hguC yr@h  
{ ~r>UjC_ B:  
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F 1zc4l6  
} 9MYt4  
3p4bOT5  
//线程睡眠 >y8Z{ALQ5  
public static void sleep(int nSecond) 3o^V$N.  
{ 57MoO  
try{ AT9SD vJ  
Thread.sleep(nSecond); Y-{spTI  
} WI~%n  
catch(Exception e) VmT5?i   
{ ^X;>?_Bk  
e.printStackTrace (); eD(a +El}  
} T]zjJwa  
} g1{wxBFE  
9E#(iP  
//日志 oaXD^H\  
public static void log(String sMsg) sO6t8)$b  
{ %4-pw|':  
System.err.println(sMsg); hBqu,A  
} U&/S  
>S3 >b  
<A&R%5Vs  
public static void log(int sMsg) *oWzH_  
{ =N0cz%  
System.err.println(sMsg); =~S   
} o{Ep/O`  
} uJ y@  
vVf!XZF  
d!X?R}  
/* 5(|ud)v  
**TestMethod.java HWU{521  
*/ ZT8j9zs  
package NetFox; Oxvw`a#  
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public class TestMethod { puyL(ohem  
j w462h  
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public TestMethod() ;lEiOF+d  
{ ///xx/weblogic60b2_win.exe +=8Po'E^!d  
try{ x}[` -  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ,5?MRqCM  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); W!^=)Qs  
SiteFileFetch fileFetch = new SiteFileFetch(bean); l`]!)j|+  
fileFetch.start(); M*HG4(n0  
} !Ch ya  
catch(Exception e){e.printStackTrace ();} e_;6UZ+  
igL^k`&5^"  
/Rz,2jfRx'  
} 6};oLnO  
o
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/W>"G1)  
public static void main(String[] args) 7L6M#B[)e5  
{ ?n+\T'f!  
new TestMethod(); q<8HG_  
} Z}C%%2Iz  
} aKy|$ {RC  
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