http断点续传简单实现（java)

/* HC0juT OiO  
**SiteFileFetch.java ~Ps*i]n(  
*/  /SvhOi  
package NetFox; g`EZLDjt  
import java.io.*; w0QtGQ|  
import java.net.*; rcnH^P  
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public class SiteFileFetch extends Thread { W 4{ T<  
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SiteInfoBean siteInfoBean = null; //文件信息Bean FT).$h~+4  
long[] nStartPos; //开始位置 iIfiv<(ChM  
long[] nEndPos; //结束位置 ?pL|eS7  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 tX*@r  
long nFileLength; //文件长度 B=Hd:P|  
boolean bFirst = true; //是否第一次取文件 ]&'!0'3`  
boolean bStop = false; //停止标志 9~p;iiKGG  
File tmpFile; //文件下载的临时信息 EPo)7<|>  
DataOutputStream output; //输出到文件的输出流 ZbRRDXk!  
H`[FC|RYyE  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） B<W}:>3  
public SiteFileFetch(SiteInfoBean bean) throws IOException +'H[4g`  
{ X[z;P!U  
siteInfoBean = bean; pj'gTQ),0  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); <O jK $KV  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 2OG/0cP  
if(tmpFile.exists ()) f/\!=sa:  
{ 8 Ku9;VEk  
bFirst = false; &+9 ;  
read_nPos(); ]dycesc'  
} \Y


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else _KRnx-  
{ * :"*'  
nStartPos = new long[bean.getNSplitter()]; YznL+TD  
nEndPos = new long[bean.getNSplitter()]; ]4rmQAS7"  
} Q`CuZkP(  
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} ^![
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public void run() '!>9j,BJ  
{ <I,4Kc!  
//获得文件长度 /P
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//分割文件 E2hsSqsu=  
//实例FileSplitterFetch +Q&l}2  
//启动FileSplitterFetch线程 H
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//等待子线程返回 {/[@uMS_6]  
try{ +=WBH'  
if(bFirst) QW..=}pL  
{ CKw-HgXG  
nFileLength = getFileSize(); lw=kTYbq  
if(nFileLength == -1) LcKc#)'EE  
{ g}9,U&$]y  
System.err.println("File Length is not known!"); l@Lk+-[D  
} +m_.?V6  
else if(nFileLength == -2) o HK  
{ HB9"T5Pd*  
System.err.println("File is not access!"); &0 QUObK  
} `(W"wC  
else F"Dr(V  
{ RXRbW%b  
for(int i=0;i<nStartPos.length;i++) 9FEhl~&  
{ ZfM]A)  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); COi15( G2  
} m?-)SA  
for(int i=0;i<nEndPos.length-1;i++) V7$ m.P#uM  
{ Yjg$o:M  
nEndPos = nStartPos[i+1]; 3P_.SF  
} %/eG{oh-  
nEndPos[nEndPos.length-1] = nFileLength; p5In9s  
} yf{\^^ i(  
} Uahh|>s  
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\:'GAByy  
//启动子线程 ;v8TT}R  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Y] 1U108  
for(int i=0;i<nStartPos.length;i++) CW`^fI9H  
{ Zl_sbIY  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), N\|B06X  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), TjpyU:R,&|  
nStartPos,nEndPos,i); IO7z}![V;  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); '[r:pwE  
fileSplitterFetch.start(); dX\OP>  
} FC 8<D  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), zBm~J%  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Vc\
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", clDn=k<  
nEndPos = " + nFileLength); mjOxmwo  
// fileSplitterFetch[nPos.length-1].start(); <B%wq>4S  
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Ioe.[&o6B  
//等待子线程结束 ]xf89[;0  
//int count = 0; uNewWtUb(  
//是否结束while循环 mB2}(DbhE  
boolean breakWhile = false; (R=ZI  
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while(!bStop) hGFi|9/-u  
{ <\*)YKjn/@  
write_nPos(); {9J|\Zz3  
Utility.sleep(500); 28JVW3&)  
breakWhile = true; s=$xnc}mf  
2?(/$F9X,  
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for(int i=0;i<nStartPos.length;i++) xpZ@DK;  
{ I N@ ~~  
if(!fileSplitterFetch.bDownOver) UXZ3~/L5 O  
{ )g=mv
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breakWhile = false; Sh;`<Ggi~  
break; K*^'tltJ  
} 
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} wgDAb#Zuk  
if(breakWhile) WLWfe-  
break; lf\"6VIsR  
/XG7M=A$o  
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//count++; yI=nu53BV  
//if(count>4) Z4z|B&  
// siteStop(); :Gz$(!j1.'  
} h-.^*=]R6  
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System.err.println("文件下载结束！"); !B[Y?b:  
} =Q"ths
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catch(Exception e){e.printStackTrace ();} <S_0=U  
} [YQtX_;w  
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//获得文件长度 !d0$cF):  
public long getFileSize() ~#EXb?#uS  
{ gISA13  
int nFileLength = -1; Pf8_6z_  
try{ [:,|g;
=Y}  
URL url = new URL(siteInfoBean.getSSiteURL()); uUl;}W  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); C&q}&=3r  
httpConnection.setRequestProperty("User-Agent","NetFox"); R||$Wi[$  
&WCVdZK:  
//G&=i$  
int responseCode=httpConnection.getResponseCode(); **AJFc  
if(responseCode>=400) vU/sQt8  
{ h*4wi.-  
processErrorCode(responseCode); "% i1zQo&  
return -2; //-2 represent access is error $sL+k 'dY  
} <)cmI .J3  
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String sHeader; c5CxR#O  
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for(int i=1;;i++) 9~,!+#  
{ i(u zb<  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); : Q,O:  
//Utility.log(in.readLine()); Z(E.F,k  
sHeader=httpConnection.getHeaderFieldKey(i); bz&9]%S<  
if(sHeader!=null) H
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{ :U1V 2f'l3  
if(sHeader.equals("Content-Length")) R^E-9S\@  
{ (1,4egMpR  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); uxrNkZia  
break; 4pDZ +}p  
} F&/}x15  
} TR?jT U  
else 4J[bh  
break; v&^N+>p  
} 7|m{hSc  
} 8Z@O%\1x6  
catch(IOException e){e.printStackTrace ();} ;r;>4+zn\  
catch(Exception e){e.printStackTrace ();} I tn?''~;  
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Utility.log(nFileLength); rI:]''PR  
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return nFileLength; j

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} =F*{O=  
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//保存下载信息（文件指针位置） OUHd@up@n  
private void write_nPos() Qe<c@i"  
{ v|kL7t)}  
try{ Q
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output = new DataOutputStream(new FileOutputStream(tmpFile)); IetV]Ff6  
output.writeInt(nStartPos.length); P.|g4EdND  
for(int i=0;i<nStartPos.length;i++) ~fA H6FdZ\  
{ zpcm`z  
// output.writeLong(nPos); =66,$~g{  
output.writeLong(fileSplitterFetch.nStartPos); ]o8~b-  
output.writeLong(fileSplitterFetch.nEndPos); V[|k:($  
} RML'C:1  
output.close(); lce~6}  
} * 8D(Lp1  
catch(IOException e){e.printStackTrace ();} el0W0T  
catch(Exception e){e.printStackTrace ();} (7aE!r\Ab  
} Lj3q?>D*^6  
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//读取保存的下载信息（文件指针位置） BgG+  
private void read_nPos() HQ|{!P\/?U  
{ TLzcQ|  
try{ m+'X8}GC#O  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 9;c]_zt  
int nCount = input.readInt(); -E!V;Tgc%U  
nStartPos = new long[nCount]; Kib?JRYt  
nEndPos = new long[nCount]; l\-(li H  
for(int i=0;i<nStartPos.length;i++) YwM;G g3  
{ r(=3yd/G$  
nStartPos = input.readLong(); 01^W Py9l  
nEndPos = input.readLong(); j@s,5:;[  
} QeAkuqT'[  
input.close(); 

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} UUql"$q
 
catch(IOException e){e.printStackTrace ();} yIThzyS  
catch(Exception e){e.printStackTrace ();} j#XU\G  
} (aH_K07  
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private void processErrorCode(int nErrorCode) vCNYqa)m:  
{ z[, `  
System.err.println("Error Code : " + nErrorCode); ;,&1  
} u"n~9!G  
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? Kn~fs8  
//停止文件下载 0r\hX6 k  
public void siteStop() whg?X&j\V  
{ K31rt-IIt  
bStop = true; RT2a:3f  
for(int i=0;i<nStartPos.length;i++) dQFx]p3L  
fileSplitterFetch.splitterStop(); @{n2R3)k B  
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} *o[*,1Pw  
} L``K. DF  
//负责部分文件的抓取 J_mpI.^Bsf  
**FileSplitterFetch.java f&>Q6 {*]  
*/ t UW'E  
package NetFox; }%rz"kB  
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import java.io.*; 0)qLW& w  
import java.net.*; SIRZ_lt$r  
8YBsYKC  
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public class FileSplitterFetch extends Thread { (sn|`k3I  
7[V'3  
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String sURL; //File URL /T*]RO4%>]  
long nStartPos; //File Snippet Start Position *Mqg_} 0Y  
long nEndPos; //File Snippet End Position FyQ^@@  
int nThreadID; //Thread's ID )P.|Xk:r  
boolean bDownOver = false; //Downing is over B|~\m~  
boolean bStop = false; //Stop identical D`.CXFI+U  
FileAccessI fileAccessI = null; //File Access interface Efw/bTEg  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException fD|ox  
{ z
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this.sURL = sURL; 413r3/  
this.nStartPos = nStart; >[Q(!Ai  
this.nEndPos = nEnd; 4 ITSDx  
nThreadID = id; z{^XU"yB  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 rq6(^I  
} 0:n
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public void run() ]}G(@9  
{ /^0Hi4+\  
while(nStartPos < nEndPos && !bStop) J]|-.Wv1  
{ 5R,/X  
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Y6fU;  
try{ Ybx4 Up@  
URL url = new URL(sURL); !H,R$3~  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); e$tKKcj0T  
httpConnection.setRequestProperty("User-Agent","NetFox"); Fu m1w  
String sProperty = "bytes="+nStartPos+"-"; ^yu^Du  
httpConnection.setRequestProperty("RANGE",sProperty); f=J#mmHw$  
Utility.log(sProperty); qx53,^2  
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InputStream input = httpConnection.getInputStream(); %-T]!3"n  
//logResponseHead(httpConnection); JUU0Tx:`9)  
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byte[] b = new byte[1024]; !Nl"y'B|  
int nRead; IEeh)aj[  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) '(u
[  
{ |vWx[=`o  
nStartPos += fileAccessI.write(b,0,nRead); o*I-~k  
//if(nThreadID == 1) OBN]bvCJ  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [N#2uo  
} Yq) wE|k/  
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Utility.log("Thread " + nThreadID + " is over!"); m2<sVTN`^  
bDownOver = true; Fz)z&WT  
//nPos = fileAccessI.write (b,0,nRead); 3r^i>r8B  
} R^_/iy  
catch(Exception e){e.printStackTrace ();} WZ~rsSZSV  
} I#S6k%-'  
} &&(sZGw  
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//打印回应的头信息 ,1F3";`n[  
public void logResponseHead(HttpURLConnection con) O-bC+vB]M  
{ cy/;qd+!M  
for(int i=1;;i++) #xE"];  
{ P7"g/j""  
String header=con.getHeaderFieldKey(i); |{Z?a^-NJ  
if(header!=null) 7ktf =Y  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); M.!U;U<?  
Utility.log(header+" : "+con.getHeaderField(header)); o& $Fc8bH  
else *]O[ZjyOY  
break; LYavth`@h  
} .azdAq'r&\  
} J0lTp /  
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public void splitterStop() n>Q/XQXB  
{ #$X_,P|D  
bStop = true; [ZOo%"M_Y  
} I`E9]b(w  
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} )5)S8~Oc  
}N*6xr*X+  
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/* +'hcFZn(T  
**FileAccess.java JTQ$p*2]  
*//文件访问(定位，写) 44mYs`]  
package NetFox;
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import java.io.*; @B*?owba>  
6#KRI%adw`  
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public class FileAccessI implements Serializable{ !ZD[ $lt+  
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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 J/M1#sE  
RandomAccessFile oSavedFile; oAA%pZ@  
long nPos; t!AHTtI  
I/
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public FileAccessI() throws IOException 73rr"> 9#0  
{ = %\;7  
this("",0); 'h.{fKG]ME  
} [>oq~[e)?  
/ \!hW-+]W  
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public FileAccessI(String sName,long nPos) throws IOException 7y&Fb  
{ +k
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oSavedFile = new RandomAccessFile(sName,"rw"); q4|TwRx
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this.nPos = nPos; G5Y 8]N  
oSavedFile.seek(nPos); nUz2~z  
} `)*
  
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public synchronized int write(byte[] b,int nStart,int nLen) <}pqj3  
{ Y<#WC#3=  
int n = -1; W r);A{  
try{ h$_Wh(  
oSavedFile.write(b,nStart,nLen); \RnGKQ"4  
n = nLen; Jb#*QJ=  
} (?72 vCc  
catch(IOException e) 5^t68 WOl  
{ sf2_x>U1  
e.printStackTrace (); {W62%>v  
} #)AcK|*y  
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return n; jX$TiG  
} o) `zb?  
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} -IMm#  
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/* .;u(uB;J6  
**SiteInfoBean.java &n|#jo(gS  
*/ ~Us1F=i_Q  
package NetFox; y/K%F,WMf  
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public class SiteInfoBean { su<_?'uH  
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private String sSiteURL; //Site's URL :c"J$wT/  
private String sFilePath; //Saved File's Path E j@M\  
private String sFileName; //Saved File's Name YES!?^}  
private int nSplitter; //Count of Splited Downloading File c|x:]W'ij  
@I2m4Q{O  
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public SiteInfoBean() %;(+s7  
{//nSplitter的缺省值为5 >|KfO>  
//default value of nSplitter is 5 j0L9Q|s  
this("","","",5); W1$B6+}Z0V  
} :Qh5ZO&G0  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter)
k2sb#]-/}  
{ , d ?4"8_  
sSiteURL= sURL;
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sFilePath = sPath; Jxi>1  
sFileName = sName; g-U'{I5F  
this.nSplitter = nSpiltter; Mc oHV]x  
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} e2*0NT^R  
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public String getSSiteURL() %gSqc }v*  
{ ndT:,
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return sSiteURL; Vj_(55WQ  
} d*khda;Vj  
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public void setSSiteURL(String value) YiB]}/  
{ EShc1KPqc  
sSiteURL = value; C_dsYuQ5R  
} daE/v.a4|  
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E D*=8s2  
public String getSFilePath() 18z{d9'F   
{ 90|p]I%  
return sFilePath; YR'?fr  
} n9]^v-]K  
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public void setSFilePath(String value) *>V6KW  
{ h#@l'Cye  
sFilePath = value; A9qCaq{  
} J0a]Wz%  
i:Pg&474f  
yc|C}
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public String getSFileName() R[LVx-e7'  
{ }oigZI(1  
return sFileName; `I,A7b  
} [6K2V:6:  
H/Cv?GJF  
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public void setSFileName(String value) V.)y7B  
{ qF`;xa%,}  
sFileName = value; .3?'+KZ,  
} %eT4Q~}5"  
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sSd  
public int getNSplitter() z@>z.d4  
{ Wa #,>  
return nSplitter; :^0g}8$<  
} I+D`\OSL  
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public void setNSplitter(int nCount) E$.|h;i]Q  
{ 6#T?g7\pyR  
nSplitter = nCount; >C+0LF`U  
} ?=jmyDXH!  
} pu=T pSZ  
\hdR&f5q  
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/* Z{+h~?63  
**Utility.java <Xm5re.  
*/ ,r{*o6  
package NetFox; FI.S?gy0   
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public class Utility { &YO5N4X~o  
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public Utility() XtT;UBE  
{ -Hh$3Uv  
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} [4 g5{eX  
$Bz|[=  
//线程睡眠 4v3
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public static void sleep(int nSecond) SjKIn-  
{ LoOyqJ,  
try{ ^%M!!wlUH  
Thread.sleep(nSecond); ?XsL4HIx  
} ~Cks)mJs  
catch(Exception e) :|<D(YA  
{ ]O<Yr'  
e.printStackTrace (); vMzR3@4e  
} NTXT0:  
} }n6BI}n  
o80pmy7@  
//日志 eWqJ2Tt  
public static void log(String sMsg) Br]VCp  
{ -ud~'<k  
System.err.println(sMsg); 1kio.9NIp  
} $7TY
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public static void log(int sMsg) ~W5fJd0  
{ zq4,%$y8|  
System.err.println(sMsg); )K@ 20Q+0K  
} |xQj2?_z*  
} TnM}|~V  
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/* .Yha(5(  
**TestMethod.java PwF}yxkI  
*/ {zbH.V[  
package NetFox; Rr%]/%  
%|SbZ)gcQ  
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public class TestMethod { SjlkKulMF  
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E'XFn'  
public TestMethod() EoQ.d|:g  
{ ///xx/weblogic60b2_win.exe J'@I!Jc  
try{ z+wV(i97  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 1)u=&t,  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); lG\lu'<C  
SiteFileFetch fileFetch = new SiteFileFetch(bean); J4`08,  
fileFetch.start(); K/MIDH  
} nn#A-x}~;b  
catch(Exception e){e.printStackTrace ();} 5U1@wfKE3>  
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} xBB:b\  
gl]{mUZz}  
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public static void main(String[] args) . s? ''/(  
{ fD,#z&  
new TestMethod(); E_ mgYW*5  
} "ajZ&{Z  
} !Toq~,a8?  
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