http断点续传简单实现（java)

/* fw{,bJ(U  
**SiteFileFetch.java ,vG<*|pn  
*/ cCxi{a1uo  
package NetFox; {@r
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import java.io.*; T 4|jz<iK]  
import java.net.*; *+8%kn`c  
[.q(h/b  
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public class SiteFileFetch extends Thread { G5{Ot>;*%  
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SiteInfoBean siteInfoBean = null; //文件信息Bean B50 [O!  
long[] nStartPos; //开始位置 9B)lGLL}q  
long[] nEndPos; //结束位置 x.EgTvA&d  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 B#tdLv"I  
long nFileLength; //文件长度 4^Ow^7N?  
boolean bFirst = true; //是否第一次取文件 D{AFL.r{  
boolean bStop = false; //停止标志 6~Wu
`  
File tmpFile; //文件下载的临时信息 n6d^>s9J  
DataOutputStream output; //输出到文件的输出流 JfTfAq]  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 7<yp"5><)  
public SiteFileFetch(SiteInfoBean bean) throws IOException (G8  
{ Ko}2%4on  
siteInfoBean = bean; V:\]cGA{  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); s#lto0b"8  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); PV,"-Nv,  
if(tmpFile.exists ()) g2'x#%ET  
{ k,X74D+  
bFirst = false; lA{(8sKN  
read_nPos(); ZPF7m
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} 5.k}{{+  
else wZv-b*4  
{ ;i9>}]6  
nStartPos = new long[bean.getNSplitter()]; Bn-J_-%M  
nEndPos = new long[bean.getNSplitter()]; 1D$::{h  
}
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} nx;$dxx_Ws  
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public void run() ja75c~RUw  
{ hrT%XJl  
//获得文件长度 ~@YQ,\Y  
//分割文件 tE:X,Lt[  
//实例FileSplitterFetch H56 ^n<tg  
//启动FileSplitterFetch线程 -,/3"}<^78  
//等待子线程返回 S*rO0s:  
try{ i7f%^7!  
if(bFirst) N<"`ShCNM  
{ iIB9j8  
nFileLength = getFileSize(); bqjr0A7{  
if(nFileLength == -1) /u?9S/  
{ `A"Q3sf%  
System.err.println("File Length is not known!"); bpnv&EG  
} cdN/Qy  
else if(nFileLength == -2) :K;T Q  
{ ;24'f-Eri  
System.err.println("File is not access!"); w~{| S7/  
} O8$~*NFJf  
else X/wmKi  
{ QnP{$rT  
for(int i=0;i<nStartPos.length;i++) PnJ*Zea  
{ blmmm(|~|  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Lb^(E-  
} u x#.:C|  
for(int i=0;i<nEndPos.length-1;i++) f^u^-l  
{ jPpRsw>  
nEndPos = nStartPos[i+1]; DH/L`$  
} t5n2eOy~T  
nEndPos[nEndPos.length-1] = nFileLength; bk
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} lc"qqt  
} 9,w}Xe=C  
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//启动子线程 FXeV6zfrE  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 2mSD"[%  
for(int i=0;i<nStartPos.length;i++) ^A- sS~w  
{ n+X1AOE[L  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(),  *[VEF  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), @Mzz2&(dU  
nStartPos,nEndPos,i); ]u;GNz}?  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 9E^~#j@Zr  
fileSplitterFetch.start(); "NJ,0A  
} -!i;7[N  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,7t3>9-M"  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); D>ojW|@}  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", z2.*#xTZn  
nEndPos = " + nFileLength); Uld_X\;Q4  
// fileSplitterFetch[nPos.length-1].start(); ([[)Ub$U  
sE-x"c  
C?{D"f`[]  
//等待子线程结束 Y:rJK|m  
//int count = 0; 0GS{F8f~,  
//是否结束while循环 gH5CB%)  
boolean breakWhile = false; 2rF?Q?$,B  
V;H d)v(j  
W^003*m~~K  
while(!bStop) yLjV[qP  
{ vlAO z  
write_nPos(); g'KzdG`O0  
Utility.sleep(500); h-Tsi:%b  
breakWhile = true; {ms,q_Zr  
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for(int i=0;i<nStartPos.length;i++) t'dHCp}  
{ ?]s%(R,B5  
if(!fileSplitterFetch.bDownOver) '`9%'f)  
{ U~oBNsU"  
breakWhile = false; -,FK{[h]ka  
break; W\&WS"=~  
} wT
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} 2T//%ys=  
if(breakWhile) c!tvG*{  
break; /&*m1EN#o  
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//count++; i:V0fBR[>  
//if(count>4) j|&{e91,?  
// siteStop(); Ko1AaX(I'+  
} [u/zrpTk  
>{j,+$%kp  
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System.err.println("文件下载结束！"); b^uP^](J  
} o}WB(WsG  
catch(Exception e){e.printStackTrace ();} ^zvA?'s  
} jz|Wj  
AeNyZ[40T  
W2}%zux  
//获得文件长度 u&1j>`~qJ  
public long getFileSize() Ul'~opf  
{ *Gg1h@&  
int nFileLength = -1; 0t5Q9#RY  
try{ hknwis%y  
URL url = new URL(siteInfoBean.getSSiteURL()); T)b3N|ONB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); EO4"Z@ji  
httpConnection.setRequestProperty("User-Agent","NetFox"); *\=2KIF'  
aDm-X r  
UI|v/(_^F  
int responseCode=httpConnection.getResponseCode(); 2"pE&QNd  
if(responseCode>=400) MILIu;[{#r  
{ k)H[XpM  
processErrorCode(responseCode); {toyQ)C7  
return -2; //-2 represent access is error B'G*y2UnG  
} L LYHr  
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L eG7x7n  
String sHeader; '#cT4_D^lI  
 opUKrB  
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for(int i=1;;i++) c[wQJc  
{ !A'
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); |@o]X?^  
//Utility.log(in.readLine()); E
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sHeader=httpConnection.getHeaderFieldKey(i); 2+T8Y,g  
if(sHeader!=null) c8k6(#\  
{ K#9(|2J%  
if(sHeader.equals("Content-Length")) ~pd1)  
{ E1Ru)k{B  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 4i+PiD:H  
break; Sb:zN'U  
} !1a|5 xrn  
} ch5`fm  
else G1#Bb5q:  
break; <FUqD0sQ  
} D,}'E0  
} 1jUhG2y  
catch(IOException e){e.printStackTrace ();} PBxK>a  
catch(Exception e){e.printStackTrace ();} ?z)y%`}  
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Utility.log(nFileLength); an$]IN  
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return nFileLength; *f0.=?  
} 1^x2WlUm4  
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//保存下载信息（文件指针位置） s%L" c  
private void write_nPos() #FQm/Q<0
 
{ <\}Y@g8  
try{ e\d5SKY  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Z!*8JaMT  
output.writeInt(nStartPos.length); `L"p)5H  
for(int i=0;i<nStartPos.length;i++) TzevC$m;z  
{ A1k&` |k  
// output.writeLong(nPos); ~q8V<@?  
output.writeLong(fileSplitterFetch.nStartPos); JL.ydH79  
output.writeLong(fileSplitterFetch.nEndPos); @ V7ooo!  
}
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output.close(); h87L8qh9  
} aV?}+Y{#  
catch(IOException e){e.printStackTrace ();} 8H3!; ]  
catch(Exception e){e.printStackTrace ();} *&hXJJ[+  
} {0)WS}&  
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//读取保存的下载信息（文件指针位置） <D;H}ef  
private void read_nPos() nIT^'  
{ YA;8uMqh;  
try{ Y&05 *
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 5QL9w3L  
int nCount = input.readInt(); YzhN|!;!k  
nStartPos = new long[nCount]; ?9('o\N:  
nEndPos = new long[nCount]; 2=Y_Qrhi  
for(int i=0;i<nStartPos.length;i++) +4:+qGAJ{  
{ 
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nStartPos = input.readLong(); :i,c<k  
nEndPos = input.readLong(); ktw!T{  
} eX l%Qs#Y  
input.close(); 7u`}t83a  
} $vw}p.  
catch(IOException e){e.printStackTrace ();} E9Xk8w'+  
catch(Exception e){e.printStackTrace ();} YW$x:  
} e@2Vn? 5  
]!tYrSM!  
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private void processErrorCode(int nErrorCode) YAC zznN  
{ hml\^I8Q>F  
System.err.println("Error Code : " + nErrorCode); |Z7bd^  
} Y3MR:{}  
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xwH|ryfs,Z  
//停止文件下载 VrGb;L'[  
public void siteStop() #g`cih=QL  
{ Lx
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bStop = true; )V$!  
for(int i=0;i<nStartPos.length;i++) |v%RjN  
fileSplitterFetch.splitterStop(); ! ^*;c#  
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} Pl5NHVr  
} L^al1T  
//负责部分文件的抓取 ]B
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**FileSplitterFetch.java zc,9Qfn  
*/ vzrD"  
package NetFox; C(|T/rQ-  
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;
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import java.io.*; 8.%a"sxr  
import java.net.*; +uiH0iGS  
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public class FileSplitterFetch extends Thread { !e\R;bYM  
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bZ22O"F  
String sURL; //File URL /'=^^%&:B  
long nStartPos; //File Snippet Start Position & Dl
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long nEndPos; //File Snippet End Position ^xNe Eb  
int nThreadID; //Thread's ID -MW(={#  
boolean bDownOver = false; //Downing is over tG^?fc  
boolean bStop = false; //Stop identical 8
8=c3^  
FileAccessI fileAccessI = null; //File Access interface N9h@1'>  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException rKs WS~U  
{ *0@; kD=  
this.sURL = sURL; b%jG?HSu  
this.nStartPos = nStart; {f-/,g~  
this.nEndPos = nEnd; ^]!1'xg  
nThreadID = id; V #\ZS{'J  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 sS2E8Z2  
} f5qHBQ  
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public void run() iK:qPrk-  
{ j72]_G  
while(nStartPos < nEndPos && !bStop) vyOC2c8  
{ QZa#iL  
'xXqEwi4  
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try{ F`V[G(f+r  
URL url = new URL(sURL); }%d-U;Tt2  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #5:A?aj  
httpConnection.setRequestProperty("User-Agent","NetFox"); !E#.WX  
String sProperty = "bytes="+nStartPos+"-"; }'0Xz9/ l  
httpConnection.setRequestProperty("RANGE",sProperty); _@;3$eB  
Utility.log(sProperty); z2q5f:d8  
^PR,TR.  
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InputStream input = httpConnection.getInputStream(); $M<4Bqr  
//logResponseHead(httpConnection); ~dr1Qi#j?  
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s /q5o@b{  
byte[] b = new byte[1024]; +9F#~{v`4a  
int nRead; LU7)F,ok  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) f\r4[gU@  
{ >^GCSPe  
nStartPos += fileAccessI.write(b,0,nRead); 17]
31  
//if(nThreadID == 1) i
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "?&bh@P&  
} v!hs~DnUZ  
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Utility.log("Thread " + nThreadID + " is over!"); |(v=1#
i  
bDownOver = true; pyJOEL]1F  
//nPos = fileAccessI.write (b,0,nRead); "{"2h>o#D}  
} NKhR%H  
catch(Exception e){e.printStackTrace ();} (NN14  
} Hf!4(\yN  
} Ck%(G22-  
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b<78K5'  
//打印回应的头信息 VCRv(Ek  
public void logResponseHead(HttpURLConnection con) <7] Y\{+  
{ >:E-^t%  
for(int i=1;;i++) nJH%pBc  
{ rh&Eu qE%  
String header=con.getHeaderFieldKey(i); JP*mQzZL  
if(header!=null) )nxIxr0d-  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); dk`!UtNNRa  
Utility.log(header+" : "+con.getHeaderField(header)); w=o m7%J@l  
else '[8
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break; uC

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} gt(nZ
  
} e`1s[ ^B  
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public void splitterStop() .3&OFM  
{ ,)G+h#Y[*  
bStop = true; _cN)q  
} 2Jv4l$$;*  
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} YaNVpLA  
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/* SoIMftX  
**FileAccess.java ,1L^#?Q~  
*//文件访问(定位，写) 0X w?}  
package NetFox; iJeT+}  
import java.io.*; WU_Q 7%+QS  
~'iuh>O)  
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public class FileAccessI implements Serializable{ SfT]C~#$N  
j)Gr@F>  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 0@;E8^pa  
RandomAccessFile oSavedFile; '"a8<7  
long nPos; VF.S)='>Eu  
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public FileAccessI() throws IOException \W!<xE  
{ z)Gr`SA<  
this("",0); 2e&Zs%u  
} 9AaixI  
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5/<Y,eZ/  
public FileAccessI(String sName,long nPos) throws IOException 5Jp>2d  
{ w
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oSavedFile = new RandomAccessFile(sName,"rw"); hQO~9mQ+!  
this.nPos = nPos; V-57BKeDz  
oSavedFile.seek(nPos); h/ic-iH(>  
} '1aOdEZA*  
~mU#u\r(*  
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public synchronized int write(byte[] b,int nStart,int nLen) Bvwk6NBN  
{ 6|9fcIh]B  
int n = -1; MwZ`NH|n3"  
try{ 42~;/4  
oSavedFile.write(b,nStart,nLen); ;lldxS  
n = nLen; va)\uXW.N  
} "[G P)nC  
catch(IOException e) (1R,  
{ %pdfGM9g  
e.printStackTrace (); azSS:=A  
} {k>m5L  
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return n; #"jWPe,d  
} `S2=LJ  
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} ?mMd6U&J  
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X~x]VKr/  
/* FD8aO?wvg  
**SiteInfoBean.java umj7-fh  
*/ +IU]=qS  
package NetFox; dW91nTQ:  
A="h}9ok  
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public class SiteInfoBean { 1}N5WBp  
9yQ[*  
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private String sSiteURL; //Site's URL :f`1  
private String sFilePath; //Saved File's Path ^0VI J)y  
private String sFileName; //Saved File's Name
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private int nSplitter; //Count of Splited Downloading File U*zjEY:A  
!j- 7,  
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public SiteInfoBean() <K)^MLgN  
{//nSplitter的缺省值为5  ]3%Z  
//default value of nSplitter is 5 s+4G`mq>*  
this("","","",5); E*[X\70  
} QjPcfR\  
P /Js!e<\  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) H4)){\  
{ K'y;j~`-  
sSiteURL= sURL; ~6R| a  
sFilePath = sPath; Iu%S><'+  
sFileName = sName; wAITE|H<zj  
this.nSplitter = nSpiltter; G|.>p<q  
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} T*z >
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public String getSSiteURL() @ %kCe>r  
{ 9Y~A2C  
return sSiteURL; b{9q   
} U<*ZY`B3  
7\5;;23N4  
faThXq8B  
public void setSSiteURL(String value) :o=[Zp~B4d  
{ Q[S""P.Z|  
sSiteURL = value; 5PG%)xff*  
} ~c+0SuJ  
lQldW|S>  
_"=Yj3?G%  
public String getSFilePath() &p0*:(j  
{ wS#.Wzp.w  
return sFilePath; ,qyH B2v  
} <1>\?$)D  
rm
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public void setSFilePath(String value) //Ck1cI#h  
{ 3S ,D~L^  
sFilePath = value; xn}sh[<:P  
} W& w-yZ  
A2!7a}*1(  
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public String getSFileName() `A])4q$  
{ rXd
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return sFileName;
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} $xJVUV  
LS*^TA(I[  
 5k{a(I  
public void setSFileName(String value) aovRm|aOo'  
{ t?iCq1  
sFileName = value; UF3WpA  
} p=V (_  
,~p'p)  
" P c"{w  
public int getNSplitter() s8Xort&  
{ y4^6I$M7V  
return nSplitter; MS)(\&N  
} Zqc+PO3lw  
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J.N%=-8  
public void setNSplitter(int nCount) FhVi|Va  
{ 80U07tJ  
nSplitter = nCount; 
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} <iDqt5)N  
} Q5b~5a  
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/* u^&2T(xGi  
**Utility.java Au(zvgP  
*/ K"B2 SsC  
package NetFox;  *(5y;1KU  
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public class Utility { {W*_^>;K  
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public Utility() # Un>g4>Rh  
{ jp?;8rS3  
o\6A]T=R  
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} h.+{cOA;n  
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//线程睡眠 f6@fi`U,  
public static void sleep(int nSecond) Qvo(2(  
{ =>Ss:SGjT  
try{ ~$xLR/{y  
Thread.sleep(nSecond); *[K\_F?^h  
} Rrh?0qWs  
catch(Exception e) ?\[2Po]n  
{ K8xwPoRL  
e.printStackTrace (); v%N/mL+5L  
} ,
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} |L|)r)t  
g_'F(An  
//日志 Teq1VK3Hr  
public static void log(String sMsg) R(_UR)G0 @  
{ =xzDpn>f  
System.err.println(sMsg); ]XX9.Xh=-  
} 4JF)w;X}  
`\!oY;jk  
|Yq0zc!  
public static void log(int sMsg) )c~1
s  
{ wV\;,(<x=%  
System.err.println(sMsg); yO}RkRA  
} f`Km ctI  
} 'wh2787  
Y JzKE7%CO  
Bc1[^{`bq^  
/* s>y=-7:N  
**TestMethod.java LvP{"K;   
*/ FnkB z5D  
package NetFox; 4?Mb>\n%<^  
!&4<"wQ  
ch2Qk8  
public class TestMethod { (Uk1Rt*h  
Tc{r;:'G<  
cspO5S>#  
public TestMethod() N~I2~f  
{ ///xx/weblogic60b2_win.exe o#(z*v@  
try{ yL =*yC  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); s-^B)0T!  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); #=6A[<qX  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 3a#X:?  
fileFetch.start(); ~3p :jEM.[  
} }~gBnq_DDU  
catch(Exception e){e.printStackTrace ();} p4},xQzB  
8)I,WWj  
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} (`V  
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public static void main(String[] args) yO@KjCv"  
{ M9mC\Iz[  
new TestMethod(); ym*,X@Qg^  
} $|0_[~0-n  
} R7'a/  
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