http断点续传简单实现（java)

/* ;yO7!
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**SiteFileFetch.java @OlV6M;qJ  
*/ w%[`'_[  
package NetFox; T7=~l)I  
import java.io.*; agFWye  
import java.net.*; D'Gmua]
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public class SiteFileFetch extends Thread { xA9{o+  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Q
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long[] nStartPos; //开始位置 N
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long[] nEndPos; //结束位置 T)r
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 J34lu{'if  
long nFileLength; //文件长度  CKv[E  
boolean bFirst = true; //是否第一次取文件 6 ztM(2[  
boolean bStop = false; //停止标志 <Vk^fV  
File tmpFile; //文件下载的临时信息 T&=1IoOg  
DataOutputStream output; //输出到文件的输出流 fr%}
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） MhZT<6  
public SiteFileFetch(SiteInfoBean bean) throws IOException Ncu\;K\N  
{ F$FCfP7  
siteInfoBean = bean; 6XO%l0dC.  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); YoKY&i6r}  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); S/|'ggC  
if(tmpFile.exists ()) qmcLG*^,  
{ dM(}1%2  
bFirst = false; lk6*?EJ  
read_nPos(); .4
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} NGlX%j4j  
else KF|<A@V  
{ fRe$}KX
 
nStartPos = new long[bean.getNSplitter()]; eM*@zo<-  
nEndPos = new long[bean.getNSplitter()]; {<a(1#{  
} eXI^9u
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} A`4j=OF\  
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public void run() Pgs^#(^>  
{ O>zM(I+p  
//获得文件长度 95,y@~*]  
//分割文件 >`a)gky%~  
//实例FileSplitterFetch y8Bi5Ae,+1  
//启动FileSplitterFetch线程 {4g1Wr5=  
//等待子线程返回 gd6We)&  
try{ -<jb>8  
if(bFirst) ~\c]!%)o  
{ qTnfiYG}  
nFileLength = getFileSize(); X 5LI  
if(nFileLength == -1) (
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{ uuzDu]Gwu  
System.err.println("File Length is not known!"); \Clz#k8l1  
} Y%b 5{1  
else if(nFileLength == -2) 8W 9%NW3&  
{ a3L]'E'*#  
System.err.println("File is not access!"); sT9P  
} #
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else &>Q_  
{ nKJJ7'$'3  
for(int i=0;i<nStartPos.length;i++) UB
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{ &_ Ewu@4  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); lM C4j  
} g83!il\  
for(int i=0;i<nEndPos.length-1;i++) ]BU,*YaB  
{ 7'_zJI^  
nEndPos = nStartPos[i+1]; AG2iLictv  
} MPMJkL$F
^  
nEndPos[nEndPos.length-1] = nFileLength; .9WJ/RKZ\D  
} 9)Y]05us  
} L=Q-r[  
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//启动子线程 kIV/o  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; @6>R/]  
for(int i=0;i<nStartPos.length;i++) I.j`h2  
{ wHk4BWg-  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2f>lgZ!  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ^u#!Yo.!(  
nStartPos,nEndPos,i); TSmuNCR  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); eP-q[U?$n  
fileSplitterFetch.start(); o(w1!spA  
} Y'-BKZv!  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6TxZ^&=  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Z mF}pa,gd  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", O,ZvV3  
nEndPos = " + nFileLength); ="RDcf/  
// fileSplitterFetch[nPos.length-1].start(); OC9_EP\"  
!SIGzj  
AZxx%6  
//等待子线程结束 A"k6n\!n;  
//int count = 0; Aj.TX%}`h  
//是否结束while循环 nbMnqkNb  
boolean breakWhile = false; VcT(n7  
{j[[E/8N!y  
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while(!bStop) =Z iyT$p  
{ ;g: TsYwM  
write_nPos(); B=#rp*vwL  
Utility.sleep(500); X3I
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breakWhile = true; h{S';/=8  
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for(int i=0;i<nStartPos.length;i++) >fI<g8N D  
{ *I`, L/  
if(!fileSplitterFetch.bDownOver) %up]"L&i  
{ H=z@!rJc.  
breakWhile = false; mQBq-;  
break; 3Ec5:Caz  
} m,$oV?y>j  
} XRKL;|cd  
if(breakWhile) gpsEN(.w  
break; 4QdY"s(n  

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//count++; ,2DKphh  
//if(count>4) 07Yh  
// siteStop(); Ec[=~>;n{l  
} "{&\
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System.err.println("文件下载结束！"); (tP>z+  
} .GM&]Hb  
catch(Exception e){e.printStackTrace ();} EYd`qk3  
} BS>|M}G)r  
xaX3<V@S  
 $.(%7[  
//获得文件长度 }]N7CWy  
public long getFileSize() 7qV_QZ!.  
{ QKYIBX  
int nFileLength = -1; y'xB? >|  
try{ 7w_`<b6  
URL url = new URL(siteInfoBean.getSSiteURL()); Z_D8}$!  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~K
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httpConnection.setRequestProperty("User-Agent","NetFox"); x
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3_
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int responseCode=httpConnection.getResponseCode(); )?joF)  
if(responseCode>=400) l.\Fr+*ej  
{ Cq?l>  
processErrorCode(responseCode); wy<m&M<Gr  
return -2; //-2 represent access is error pMYEL  
} Fd2Eq&:en$  
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String sHeader; Z$kff-Y4  
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for(int i=1;;i++) Y2!OJuyGc  
{ ^q_0(Vf  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 1]aM)},  
//Utility.log(in.readLine()); mQtGE[  
sHeader=httpConnection.getHeaderFieldKey(i); ^E8&!s  
if(sHeader!=null) oU% rP  
{ &OK(6o2m;  
if(sHeader.equals("Content-Length")) X{P_HCd  
{ ez&v"J  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Kjc"K36{L  
break; SfyZ,0  
} )TFaG[tj  
} VZ'[\3J  
else [MdVgJ9'  
break; HvN!_}[  
} _-x|g~pV*  
} di>"\On-  
catch(IOException e){e.printStackTrace ();} 2B3H-`  
catch(Exception e){e.printStackTrace ();} ! pR&&uG  
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Utility.log(nFileLength); kq8:h  
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return nFileLength; xmb]L:4F  
} %N7b XKDP  
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//保存下载信息（文件指针位置） "yXKu)_  
private void write_nPos() lPSyFb"  
{ Zk__CgS#  
try{ /T]2ZX>  
output = new DataOutputStream(new FileOutputStream(tmpFile)); H ifKa/}P8  
output.writeInt(nStartPos.length); /@X!  
for(int i=0;i<nStartPos.length;i++) 
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{ 5'd$TC  
// output.writeLong(nPos); t,M_  
output.writeLong(fileSplitterFetch.nStartPos); *BH*   
output.writeLong(fileSplitterFetch.nEndPos); ZZ?
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} E?z3 D*U  
output.close(); __teh>MC  
} *9y)B|P^  
catch(IOException e){e.printStackTrace ();} )o;/*h%@
  
catch(Exception e){e.printStackTrace ();} vP`Sz}FU  
} a$yAF4HR
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//读取保存的下载信息（文件指针位置） ~m8".Z"  
private void read_nPos() 0f&B;?)!  
{ .LhIB?  
try{ u)Y~+ [Q  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); O`Er*-O  
int nCount = input.readInt(); :f G5?])  
nStartPos = new long[nCount]; LQ`s>q  
nEndPos = new long[nCount]; )=;GQ*<8Zs  
for(int i=0;i<nStartPos.length;i++) Wf/r@/q  
{ f_Ma~'3  
nStartPos = input.readLong(); dKTyh:_{  
nEndPos = input.readLong(); 3p6QJuSB  
} Oq@+/UWX
 
input.close(); f(:+JH<P~  
} njtz,qt_;G  
catch(IOException e){e.printStackTrace ();} "XlNKBgM  
catch(Exception e){e.printStackTrace ();} 6=U81  
} DDQ}&`s  
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private void processErrorCode(int nErrorCode) ug{@rt/"Z  
{ ~~a,Fyko2  
System.err.println("Error Code : " + nErrorCode); ]$Pl[Vegy  
} x? tC2L  
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//停止文件下载 \(2w/~  
public void siteStop() (hNTr(z  
{ `qnp   
bStop = true; Y[)b".K  
for(int i=0;i<nStartPos.length;i++) e+6mbJ7y  
fileSplitterFetch.splitterStop(); pFgpAxl  
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} |a4cER.'2^  
} a?jUm.  
//负责部分文件的抓取 |0ATH`{  
**FileSplitterFetch.java "5 ;fuM1  
*/ w^z5O6   
package NetFox; ,`PC^`0c}o  
-{`8Av5)E%  
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import java.io.*; dp
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import java.net.*; N(uHy@  
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public class FileSplitterFetch extends Thread { 5;'(^z-bL  
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String sURL; //File URL -f
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long nStartPos; //File Snippet Start Position H3-(.l[!b)  
long nEndPos; //File Snippet End Position ^Ej$o@PH  
int nThreadID; //Thread's ID E|{(O
  
boolean bDownOver = false; //Downing is over %"-bG'Yc  
boolean bStop = false; //Stop identical <G|i!Pm  
FileAccessI fileAccessI = null; //File Access interface j5m KJC  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException A,67)li3  
{ -Zq\x'  
this.sURL = sURL; -yOwX2Wv5;  
this.nStartPos = nStart; z^lcc7  
this.nEndPos = nEnd; m%zo? e  
nThreadID = id; 3LGX ^J<f  
fileAccessI = new FileAccessI(sName,nStartPos);//定位  _
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} G0#<SJ,)  
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public void run() JfD-CoQS'  
{ fg$#ZCi  
while(nStartPos < nEndPos && !bStop) }uZ/^_U.  
{
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try{ M~%P1@%  
URL url = new URL(sURL); Hjhgu=  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); &~mJ ).*  
httpConnection.setRequestProperty("User-Agent","NetFox"); '8J!(+  
String sProperty = "bytes="+nStartPos+"-"; YRg"{[+#]k  
httpConnection.setRequestProperty("RANGE",sProperty); <OY (y#x  
Utility.log(sProperty); [|".j#ZlK  
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InputStream input = httpConnection.getInputStream(); nTsKJX%\  
//logResponseHead(httpConnection); Pi+p
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byte[] b = new byte[1024]; WwsH7X)  
int nRead; rn^cajO^  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) )]}G
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{ 9?X8H1  
nStartPos += fileAccessI.write(b,0,nRead); CvHE7H|-{  
//if(nThreadID == 1) 3d
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); acrR  
} AH{#RD  
cY5w,.Q/!  
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Utility.log("Thread " + nThreadID + " is over!"); 6Hbu7r*tm  
bDownOver = true; g,9&@g/  
//nPos = fileAccessI.write (b,0,nRead); 3 ,zW6-}  
} M>E~eb/  
catch(Exception e){e.printStackTrace ();} ?g\emhG  
} Nq9\2p  
} jme
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\q
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//打印回应的头信息 {xAd>fGG+y  
public void logResponseHead(HttpURLConnection con) vPz$+&{I  
{ 7fI2b,~  
for(int i=1;;i++) oXjoQ  
{ 9X?RJ."J  
String header=con.getHeaderFieldKey(i); bwM?DY
 
if(header!=null) :8K}e]!c1  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ?K+q~DzNSD  
Utility.log(header+" : "+con.getHeaderField(header)); ~NZL~p  
else ;j.-6#n  
break; F\, vIS  
} cYp
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} zauDwV=  
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public void splitterStop() lEg
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{ h@E7wp1'~  
bStop = true; WkiPrQ0]:  
} -woFKAy`  

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} u^G Y7gah  
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/* ta6>St7.  
**FileAccess.java l\F71pwSI  
*//文件访问(定位，写) V@g v  
package NetFox; nK32or3  
import java.io.*; [GPCd@  
NVg
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public class FileAccessI implements Serializable{ G^N@r:RS  
4Q/{lqG  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 OP<N!y?[  
RandomAccessFile oSavedFile; "u]&~$  
long nPos; GeDI\-  
r;xy/*%Mtj  
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public FileAccessI() throws IOException 99.F'Gz  
{ %ufh  
this("",0); GGnlkp& E  
} ?2l`%l5(  
}zks@7kf  
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public FileAccessI(String sName,long nPos) throws IOException }
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{ m~ 5"q%;  
oSavedFile = new RandomAccessFile(sName,"rw"); cF4,dnI  
this.nPos = nPos; aZ$5"  
oSavedFile.seek(nPos); Y0.'u{J*  
} S2DG=hi`GK  
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public synchronized int write(byte[] b,int nStart,int nLen) :_y!p  
{ N2k<W?wQ  
int n = -1; ^D5Jqh)
 
try{ rf-yUH]&S  
oSavedFile.write(b,nStart,nLen); q8&l%-d`  
n = nLen; d|oO2yzWv  
} ]/kpEx  
catch(IOException e) $'I&u  
{ S :8  
e.printStackTrace (); F$(ak;v}  
} +}N'Xa/Jt  
t/Y0e#9,  
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return n; 4xEw2F  
} zPND$3&'  

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}  *<W8j[?  
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/* w6Nnx5Ay  
**SiteInfoBean.java SF&2a(~s  
*/ n8F~!|lQ0  
package NetFox; k'PvTWR  
4")`}T  
2?GMKd)  
public class SiteInfoBean { }mXYS|{  
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private String sSiteURL; //Site's URL Qw:!Rw,x  
private String sFilePath; //Saved File's Path E0R6qS:'  
private String sFileName; //Saved File's Name >> "gb/x,  
private int nSplitter; //Count of Splited Downloading File \?>M?6D  
IC&P-X_aP  
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public SiteInfoBean() BH1h2OEe#  
{//nSplitter的缺省值为5 w^ut,`yWR  
//default value of nSplitter is 5 oR&z,%0wMK  
this("","","",5); jtlRom}  
} *9"x0bth  
s6@mXO:H^  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Mn(iAsg  
{ 7n6g;8xE  
sSiteURL= sURL; k1q/L|')  
sFilePath = sPath; oDV6[e  
sFileName = sName; ;o3gR4u_L  
this.nSplitter = nSpiltter; @]vY[O!&;  
EM*I%|n@m  
29,ET}~  
} IGcq*mR=  
s@ r{TXEn  
#M16qOEw  
public String getSSiteURL() /W$i8g  
{ ];LFv5"  
return sSiteURL; +q}t%K5  
} ,< x/  
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public void setSSiteURL(String value) \jtA8o%n  
{ \"oZ
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sSiteURL = value; ^sD M>OHp  
} SOhM6/ID2/  
^ *"fC  
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public String getSFilePath() WHY/x /$  
{ B={_}
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return sFilePath; Q+=pP'cV  
} tO8\} u4c  
*z?Uh$I4  
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public void setSFilePath(String value) ^obuMQ;  
{ ^PTf8o  
sFilePath = value; 3&+dyhL'w  
} Z5>~l  
D#b*M)X"  
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public String getSFileName() -!Myw&*\V  
{ A/>Q5)  
return sFileName; (QiA5!wg  
} +gX
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,2nu*+6Y/  
b$,Hlh,^  
public void setSFileName(String value) <bKtAf  
{ z#G
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sFileName = value; </{Zb.  
} cjEqN8  
$V(]z`b&  
TU0-L35P1  
public int getNSplitter() D=-}&w_T"  
{ v.Ba  
return nSplitter; Q?k
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} {R!yw`#^B  
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sllT1%?  
public void setNSplitter(int nCount) "l56?@-x  
{ `N *:,8j  
nSplitter = nCount; A)&FcMO*z  
} N&NBn(  
} a:)FWdp?9  
[CI&4)#  
< '5~p$  
/* .>B'oD  
**Utility.java 2!^=G=H/  
*/ 8%7%[WC#  
package NetFox; &:&89<C'  
?bB>}:~j)  
*p}mn
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public class Utility { gF{ehU%  
v|%41xOsr  
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public Utility() !%G]~  
{ 7Jf~Bn  
j,M$l mR')  
*): |WDR  
} |h]V9=  
fg^25g'_  
//线程睡眠 ZRagM'K  
public static void sleep(int nSecond) vA/SrX.  
{ G)Gp}4gV}  
try{ _uQ]I^'D  
Thread.sleep(nSecond); 1INX#qTZ  
} z'q~%1t  
catch(Exception e) S}@7Z`  
{ Ay16/7h@hi  
e.printStackTrace (); p R'J4~  
} )7>GXZG>=  
} X.fVbePxUU  
4X
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//日志 ^PZ[;F40  
public static void log(String sMsg) S<
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{ rOSov"7  
System.err.println(sMsg); iHD!v7d7  
} x0 )V o]r  
"I.
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h6h6B.\Ld  
public static void log(int sMsg) Ei4^__g\'  
{ <7^|@L 6  
System.err.println(sMsg); %Rk|B`ST  
} u&:N`f  
} =l`)b  
NIV}hf YF  
#fuUAbU0X  
/* v"G1vSx)BT  
**TestMethod.java y]j.PT`Cw  
*/ 75# 8P?i  
package NetFox; 3V
k8'  
U#3N90,N=  
L/8oqO|  
public class TestMethod { /Q1*Vh4  
P(D>4/f3"  
%B%_[<B  
public TestMethod() LZykc c9g  
{ ///xx/weblogic60b2_win.exe OyTK,i<n  
try{ ?@b6(f xX  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); "V|Rq]_+%  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); V?{d<Ng~J  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Vq'7gJj'  
fileFetch.start(); t1']q"  
} uavATnGO{B  
catch(Exception e){e.printStackTrace ();} AFAg3/  
4=yzf  
.|,LBc!  
} 8}'iEj^e  
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\"
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public static void main(String[] args) X=sE1RB  
{ W:r[o%B  
new TestMethod(); A!lZyG!3  
} K.  ;ev  
} UsE\p9mCuV  
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