http断点续传简单实现（java)

/* :.K#=ROP  
**SiteFileFetch.java {e3XmVAI  
*/ >o#^)LN  
package NetFox; ~kkwPs2V  
import java.io.*; ~I_v {  
import java.net.*; _i-
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public class SiteFileFetch extends Thread { n*HRGJ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean _BA2^C':c{  
long[] nStartPos; //开始位置 B F,rZZL  
long[] nEndPos; //结束位置 dp&bcR&#)  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 4ZRE3^y\"  
long nFileLength; //文件长度 .&Vyo<9Ck  
boolean bFirst = true; //是否第一次取文件 o C5}[cYD`  
boolean bStop = false; //停止标志 U'Xw'?Uj  
File tmpFile; //文件下载的临时信息 "]"!"#aMv  
DataOutputStream output; //输出到文件的输出流 !GNLq.rQ  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） !aVwmd'9  
public SiteFileFetch(SiteInfoBean bean) throws IOException l5 FM>q  
{ Je5UVf3>2&  
siteInfoBean = bean; +yh-HYo`  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); E@f2hW2  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 6*cY[R|q!  
if(tmpFile.exists ()) @eQo  
{ |.s#m^"  
bFirst = false; RCS91[  
read_nPos(); WC?}a^
8  
} 'A|OVyH  
else e2onR~Cf  
{ H"_]Hq  
nStartPos = new long[bean.getNSplitter()]; 9
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nEndPos = new long[bean.getNSplitter()]; RZV8
{
  
} d+6 by,'  
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} |&>!"27;w  
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public void run() frYPC Irj  
{ pxF<L\L?:  
//获得文件长度 E8:4Z$|c  
//分割文件 }-e  
//实例FileSplitterFetch ~[|zf*ZISG  
//启动FileSplitterFetch线程 VHyP@JB  
//等待子线程返回 G?y'<+Awt  
try{ y[}O(  
if(bFirst) pO~VI
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{ ^w+jPT-n  
nFileLength = getFileSize(); fO4e[g;G  
if(nFileLength == -1) OZw<YR  
{ 7\q_^  
System.err.println("File Length is not known!"); E rf$WPA  
} 05|,-S  
else if(nFileLength == -2) wc-ll&0Z  
{ qlUw;{;p  
System.err.println("File is not access!"); 7jb{E+DrG  
} &I[ITp6y0  
else Qe~2'Hw#9  
{ 4-?'gN_  
for(int i=0;i<nStartPos.length;i++) A5lP%&tu(  
{ xTnd9'Pk`:  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); @;-6qZ  
} j'?^<4i  
for(int i=0;i<nEndPos.length-1;i++) F^],p|4f  
{ `%2e?"OOJ  
nEndPos = nStartPos[i+1]; rQncW~  
} !`B
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nEndPos[nEndPos.length-1] = nFileLength; ~N i#xa  
} >gt_C'  
} XZcT-w7  
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//启动子线程 ,sAN,?eG~  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; [n`SXBi+n  
for(int i=0;i<nStartPos.length;i++) LNp%]*h  
{ %^L:K5V  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,|: a7b]  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), sFEkxZi<  
nStartPos,nEndPos,i); /mB'Fn6)  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); a{lDHk`Wf  
fileSplitterFetch.start(); }T?MWcG4  
} XsldbN^6  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ~IHjj1s  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ez2 gy"  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", nP9@yI*7  
nEndPos = " + nFileLength); ~YIGOL"?  
// fileSplitterFetch[nPos.length-1].start(); ;%1ob f 89  
[;c'o5M&  
@-z#vJ5Qe{  
//等待子线程结束 AUloP?24  
//int count = 0; 728}K^7:  
//是否结束while循环 iA~b[20&  
boolean breakWhile = false; 5G~;g  
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while(!bStop) 5XNIX)H  
{ TA47lz q  
write_nPos(); 7'[C+/:  
Utility.sleep(500); #]s>  
breakWhile = true; Z=O2tR  
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for(int i=0;i<nStartPos.length;i++) guC/eSxv  
{ i^{.Q-  
if(!fileSplitterFetch.bDownOver) c<V.\y0x  
{ n9;+RhxA  
breakWhile = false; UarU.~Uqi  
break; WUid5e2  
} /j]r?KAzw  
} @!\g+z_"  
if(breakWhile) p{j }%)6n  
break; x@+m_y  
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//count++; =&*:)  
//if(count>4) e`Xy!@`_  
// siteStop(); Sti)YCXH  
} ?Z@FxW  
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System.err.println("文件下载结束！"); S;$@?vF  
} 9.|+KIRb  
catch(Exception e){e.printStackTrace ();} d"nz/$  
} 47_4`rzy;  
?~rF3M.=|  
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//获得文件长度 QD LXfl/  
public long getFileSize() 9&A-o  
{ %zHNX4  
int nFileLength = -1;  6h N~<  
try{ @18"o"c7j  
URL url = new URL(siteInfoBean.getSSiteURL()); 40pGu  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ^e$;I8l  
httpConnection.setRequestProperty("User-Agent","NetFox"); N2_j[Pe  
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int responseCode=httpConnection.getResponseCode(); oK h#th  
if(responseCode>=400) 7?K?-Oj  
{ 5y! 4ny_  
processErrorCode(responseCode); d"+zDc;  
return -2; //-2 represent access is error m",wjoZe*  
} ?@9kVB*|  
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{ p {a0*$5  
String sHeader; Q>nq~#3?  
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for(int i=1;;i++) kZ+nL)YQ#  
{ ^RG6h  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); : j&M&+  
//Utility.log(in.readLine()); KO(+%>^R  
sHeader=httpConnection.getHeaderFieldKey(i); }N
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if(sHeader!=null) 4NL TtK  
{ "GP!]3t  
if(sHeader.equals("Content-Length")) irCS}Dbw  
{ euM7> $`  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); AiSO|!<.N  
break; ll
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} H,q
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} bD<[OerG  
else zpr`  
break; <Mo_GTOC!  
} ]{
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} ~oI7T
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catch(IOException e){e.printStackTrace ();} Vb06z3"r  
catch(Exception e){e.printStackTrace ();} T#^  
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Utility.log(nFileLength); KotJ,s]B  
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return nFileLength; E;~gQ6vAI  
} Qvs}{h/  
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5
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//保存下载信息（文件指针位置） xL4qt=  
private void write_nPos() $ud5bT{n  
{ .Vux~A  
try{ EvIL[\Dy  
output = new DataOutputStream(new FileOutputStream(tmpFile)); !8vHN=)z  
output.writeInt(nStartPos.length); ys:1%D,,_
 
for(int i=0;i<nStartPos.length;i++) !!_K|}QOE  
{ ?yzhk7j7  
// output.writeLong(nPos); ,St#/tu  
output.writeLong(fileSplitterFetch.nStartPos); b9[;qqq@'  
output.writeLong(fileSplitterFetch.nEndPos); qSj2=dlW  
} _*6nTSL  
output.close(); r_T\%
 
} }% JLwN  
catch(IOException e){e.printStackTrace ();} +T=Z!2L  
catch(Exception e){e.printStackTrace ();} Z}.N4 /  
} ,"  
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//读取保存的下载信息（文件指针位置） 9_[TYzpB!  
private void read_nPos() }6.R.*Imz  
{ :kqJ~  
try{ Dna0M0   
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ?ltTJ(Po  
int nCount = input.readInt(); bLGgu#  
nStartPos = new long[nCount]; r#*kx#"  
nEndPos = new long[nCount]; oabc=N!7
r  
for(int i=0;i<nStartPos.length;i++) {bL6%._C  
{ ,Cj1S7GFR  
nStartPos = input.readLong(); q5?g/-_0[  
nEndPos = input.readLong(); [wP;g'F  
} w"$CV@AJ  
input.close(); R6]/g  
} ,xB&{J  
catch(IOException e){e.printStackTrace ();} d7qY(!&  
catch(Exception e){e.printStackTrace ();} :L&Bbw(  
} xn1  
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private void processErrorCode(int nErrorCode) szMh}q"u  
{ LYNd^}  
System.err.println("Error Code : " + nErrorCode); :U)q(.53  
} \%=\_"^?  
{S(?E_id5b  
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//停止文件下载 r]Bwp i%  
public void siteStop() :}TT1@  
{
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bStop = true; ]p:x,%nm  
for(int i=0;i<nStartPos.length;i++) 6+BR5Nr  
fileSplitterFetch.splitterStop(); Q.#@xaX'{`  
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} *:bNK5I.t  
}  y$7Fq'  
//负责部分文件的抓取 /8@JWK^I{  
**FileSplitterFetch.java MBRRzq%F  
*/ /E$"\m
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package NetFox; 7g_:Gv~v  
?JDZDPVJ)  
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import java.io.*; NqvL,~1G  
import java.net.*; H7?C>+ay  
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public class FileSplitterFetch extends Thread { xi8RE
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String sURL; //File URL _H>ABo  
long nStartPos; //File Snippet Start Position L B1ui  
long nEndPos; //File Snippet End Position RS!~5nk5  
int nThreadID; //Thread's ID #>GUfhou)  
boolean bDownOver = false; //Downing is over Bu">)AnN  
boolean bStop = false; //Stop identical T!eeMsI
 
FileAccessI fileAccessI = null; //File Access interface D`0II=  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :q S=_!1  
{ bVSa}&*kM  
this.sURL = sURL; x0@J~ _0  
this.nStartPos = nStart; ZdeRLX  
this.nEndPos = nEnd; j':Ybr>BR  
nThreadID = id; )Xg,;^  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 H>_ FCV8  
} p{xO+Nx1a  
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public void run() 1BwCJ7?8  
{ }MW*xtGV  
while(nStartPos < nEndPos && !bStop) [tym~ZZ]_m  
{ OJ\IdUZ  
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try{ Y>geP+-  
URL url = new URL(sURL); %@3AA<  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~b/lr  
httpConnection.setRequestProperty("User-Agent","NetFox"); @|(mR-Jj  
String sProperty = "bytes="+nStartPos+"-"; qY`)W[  
httpConnection.setRequestProperty("RANGE",sProperty); BRYhL|d~.  
Utility.log(sProperty); |lOxRUf~  
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InputStream input = httpConnection.getInputStream(); "pdmz+k8S  
//logResponseHead(httpConnection); I0P)DR  
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byte[] b = new byte[1024]; FFb`4.  
int nRead; ]WR+>)ERb  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) /cF 6{0XS9  
{ {ER! 0w/  
nStartPos += fileAccessI.write(b,0,nRead); SY>i@s+ML  
//if(nThreadID == 1) 4]A2Jl E  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); |8PUmax
 
} `Gzuk
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Utility.log("Thread " + nThreadID + " is over!"); M8a^yoZn  
bDownOver = true; lrB@n?hk  
//nPos = fileAccessI.write (b,0,nRead); /9NQ u  
} c<L^ 1,G2  
catch(Exception e){e.printStackTrace ();} &1Y

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} PN[ `p1F  
} 1%Xwk2l,8b  
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//打印回应的头信息 &$tBD@7  
public void logResponseHead(HttpURLConnection con) `}#(Ze*V:  
{ uQazUFw  
for(int i=1;;i++) (f^WC,  
{ 2s>dlz  
String header=con.getHeaderFieldKey(i); Wz}RJC7p  
if(header!=null) <uDEDb1|l  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 34k<7X`I  
Utility.log(header+" : "+con.getHeaderField(header)); 8M*[RlUJB  
else ]+;1)  
break; iM+K&\{_h  
} fu'iG7U M  
} %l%5Q;t  
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public void splitterStop() \c3zK|^  
{ ^ 
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bStop = true; A|1 TE$  
} /uS(Z-@  
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} z=:<]j#=  
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/* 87P{vf#  
**FileAccess.java l_GvdD  
*//文件访问(定位，写) dOh'9kk3  
package NetFox; 8rwkux >  
import java.io.*; =G3O7\KmH  
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4zs1BiMG  
public class FileAccessI implements Serializable{ h~haA8i?{  
?rID fEvV  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 H7n5k,  
RandomAccessFile oSavedFile; eKi/Mt  
long nPos; yG|^
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public FileAccessI() throws IOException ln%xp
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{ J/S 47J~  
this("",0); _Qg^>}]A1  
} \PU3{_G]  
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public FileAccessI(String sName,long nPos) throws IOException u}Vc2a,WV  
{ s8Kf$E^?e.  
oSavedFile = new RandomAccessFile(sName,"rw"); 'b#RfF,7H}  
this.nPos = nPos; O4@sN=o  
oSavedFile.seek(nPos); h1@|UxaE#  
} }[XzM/t  
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.WM0x{t/  
public synchronized int write(byte[] b,int nStart,int nLen) l0AgW_T  
{ Ry>c]\a]  
int n = -1; @r4ZN6Wn  
try{ >ch{u{i6  
oSavedFile.write(b,nStart,nLen); v9R#=m/
=  
n = nLen; Fq/?0B8  
} wEL$QOu$  
catch(IOException e) S
o; ;  
{ hO^8CA,5  
e.printStackTrace (); T)wc{C9w  
} m<)0XE6w  
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return n; {;0j9rr  
} 'WK}T)o  
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}  }rf_:  
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/* U">J$M@  
**SiteInfoBean.java a7'.*H]  
*/ ` W
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package NetFox; $O"S*)9  
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public class SiteInfoBean { }@MOkj  
>!O3 jb k  
Nf8."EDUW  
private String sSiteURL; //Site's URL -5,QrMM<  
private String sFilePath; //Saved File's Path =!7k/n';  
private String sFileName; //Saved File's Name tu\;I{h=0  
private int nSplitter; //Count of Splited Downloading File h<H.8.o  
[.4R ,[U  
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public SiteInfoBean() "3o{@TdU  
{//nSplitter的缺省值为5 2?YN8 n9n  
//default value of nSplitter is 5 *Wk y#  
this("","","",5); Aw
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} *KNj5>6=  
 o`S|  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) .,zrr&Po  
{ yoa"21E$  
sSiteURL= sURL; xLX<.z!r  
sFilePath = sPath; 58\rl G  
sFileName = sName; v#*9rNEj0  
this.nSplitter = nSpiltter; WNSf$D{p  
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} RM\it"g  
0,+RF"R  
~_ss[\N  
public String getSSiteURL() USfpCRj9  
{ @igGfYy  
return sSiteURL; YT\x'`>Q  
} pQ%~u3  
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public void setSSiteURL(String value) 0[ MQp"z  
{ ({ 'I;]AQ  
sSiteURL = value; {3=M-U~r  
} am.}2QZU  
#4S">u  
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public String getSFilePath() O8:$sei$  
{ .;j}:<  
return sFilePath; k(1]!c4J0  
} [=*c8  
rT$J0"*=  
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public void setSFilePath(String value) gi!{y  
{ 2mUq$kws  
sFilePath = value; SKf9 yS#  
} ut z.  
=" Q5Z6W  
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public String getSFileName() \.h!'nfF  
{
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return sFileName; sYnf #'  
} XnC`JO+7M  
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public void setSFileName(String value) 1L722I@  
{ ,)%al76E  
sFileName = value; ELoE-b)Cb  
} o,l3j|1  
dL;C4[(N  
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public int getNSplitter() Wr+?ul*_  
{ oc.H}Eb%Z  
return nSplitter;  d(PS  
} !Ra.DSL  
E
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dx['7l;I  
public void setNSplitter(int nCount) <Stfqa6FJ  
{ 0}:- t^P  
nSplitter = nCount; ;Zfglid  
} 57r?`'#*  
} bxX[$q  
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/* !ceT>i90h  
**Utility.java r[; .1,(  
*/ F-i`GMWC  
package NetFox; H}m%=?y@  
E}eu]2=nU}  
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public class Utility { l)y$c}U  
t(3<w)r2  

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public Utility() Y rq-(  
{ ?kBi9^
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7/*Q?ic  
} [@ExR*  

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//线程睡眠 PDN3=PAR/A  
public static void sleep(int nSecond) xj6ht/qq  
{ 'iy &%?  
try{ ybWb'+x  
Thread.sleep(nSecond); Vgy}0pCl  
} Fkgnc{NI  
catch(Exception e) xWkCP2$?P  
{ >E*j4gg  
e.printStackTrace (); -h=K]Y{`  
} r9!jIkILz  
} E"LSM]^^<f  
}yM /z  
//日志 :N!Fe7H,  
public static void log(String sMsg) 8@`"ZzM  
{ Z^t"!oY  
System.err.println(sMsg); sg@)IEg</v  
} 8GpPyG ],e  
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public static void log(int sMsg) 5Fh?YS=  
{ a<AT;Tc  
System.err.println(sMsg); ;3ZHm*xJx  
} Y{c_5YYf  
} "4W@p'  
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/* 0*?/s\>PS;  
**TestMethod.java EW;R^?Z  
*/ a.P7O!2Lp  
package NetFox; }T<[JXh=J  
8?ig/HSt2  
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public class TestMethod { e[txJ*SuO  
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public TestMethod() =4RXNWkud  
{ ///xx/weblogic60b2_win.exe x13t@b  
try{ 8r7}6  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); u=a5Z4N'  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); (Uo:WyVj|F  
SiteFileFetch fileFetch = new SiteFileFetch(bean); fiDwa ;,  
fileFetch.start(); g3B zi6$m  
} C$MaJHkiF  
catch(Exception e){e.printStackTrace ();} .xXe *dm%  
F
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} wNsAVUjLe  
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public static void main(String[] args) i <KWFF#  
{ XXuIWIhm  
new TestMethod(); sT|$@$bN  
} {XC1B  
} 3#)I7FG  
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