http断点续传简单实现（java)

/* #ab=]}2W_g  
**SiteFileFetch.java ^KJIT3J(#  
*/
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package NetFox; =/rIXReY  
import java.io.*; x1kb]0s<-  
import java.net.*; DN@T4!  
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public class SiteFileFetch extends Thread { -)tu$W*  
r='"X#CmV/  
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SiteInfoBean siteInfoBean = null; //文件信息Bean mu/O\'5  
long[] nStartPos; //开始位置 ArUGa(;f  
long[] nEndPos; //结束位置 WoiK _Ud  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 y3K9rf  
long nFileLength; //文件长度 MD,}-m  
boolean bFirst = true; //是否第一次取文件 )[>b7K$f  
boolean bStop = false; //停止标志 8]N+V:  
File tmpFile; //文件下载的临时信息 B{SzC=4f}  
DataOutputStream output; //输出到文件的输出流 G8lR_gD"!  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ?*z#G'3z1  
public SiteFileFetch(SiteInfoBean bean) throws IOException :sBg+MS  
{ g(Jzu'  
siteInfoBean = bean; v 6?{g  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); !z;a>[T'  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); sgo({zA`i  
if(tmpFile.exists ()) J.
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{ 1TKOvy_  
bFirst = false; RTNUHz;{L  
read_nPos(); ]cnLJ^2  
} XnQo0 R.PW  
else 0f 1Lu) 2  
{ g@.RfX=  
nStartPos = new long[bean.getNSplitter()]; #"a?3!wr  
nEndPos = new long[bean.getNSplitter()]; H85HL-{  
} H\2+cAFN#  
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} i=-zaboo  
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public void run() @#}9?>UV  
{ vS:%(Y"!<  
//获得文件长度 ;PJWd|3  
//分割文件 0sRby!  
//实例FileSplitterFetch 4?X#d)L(  
//启动FileSplitterFetch线程
s&p*.I]@>  
//等待子线程返回 0}c*u) ,  
try{ l/_3H\iM  
if(bFirst) Xz0jjO,  
{ 0CxQ@~ttl  
nFileLength = getFileSize(); A?3hNvfx  
if(nFileLength == -1) lkV% k1w  
{ y5.Z<Y  
System.err.println("File Length is not known!"); G|yX9C]R  
} Mu18s}  
else if(nFileLength == -2) 3mgFouX2x,  
{ vt[4"eU  
System.err.println("File is not access!"); 8h~v%aZ1  
} uRKCvsisX  
else n\5` JNCb  
{ ]?xF'3#  
for(int i=0;i<nStartPos.length;i++) viAvD6e  
{ N7*JL2Rnq  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ]YZ+/:#U7  
} _tL*sA>[~)  
for(int i=0;i<nEndPos.length-1;i++) =eSG7QfS  
{ 
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nEndPos = nStartPos[i+1]; fM_aDSRa!H  
} BUv;BzyV  
nEndPos[nEndPos.length-1] = nFileLength; \0Zm
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} jcN84AaRFI  
} rSB"0W7  
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8UoMOeI3  
//启动子线程 cn=~}T@~Z  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; l2=.;7IV  
for(int i=0;i<nStartPos.length;i++) 3~BL!e,  
{ }#q9>
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), tuK"}HepB  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), t/_w}  
nStartPos,nEndPos,i); ;'dw`)~jQ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 6!/e_a  
fileSplitterFetch.start(); ?};}#%971  
} ?{$Q'c_I  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), EKk~~PhW 8  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); X\hD4r"  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", \^?BC;s^C  
nEndPos = " + nFileLength); `,aPK/  
// fileSplitterFetch[nPos.length-1].start(); [Ym?"YwVX  
>ALU}o/  
oKz|hks[6  
//等待子线程结束 *(s+u~, I  
//int count = 0; ;Mc\>i/  
//是否结束while循环 Us M|OH5k  
boolean breakWhile = false;
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while(!bStop) "}Ch2K  
{ }-)2CEj3L%  
write_nPos(); /lm;.7_J+  
Utility.sleep(500); ?@(
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breakWhile = true; $/5Jc[Ow  
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for(int i=0;i<nStartPos.length;i++) "QA#  
{ m7^aa@^m  
if(!fileSplitterFetch.bDownOver) ln'7kg
 
{ ,4jkTQ*@2  
breakWhile = false; *pk*ijdB  
break; ZBcZG  
} Va\dMv-b  
} =ILs[p  
if(breakWhile) ?a7PxD.  
break; @~U: |h  
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f
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//count++; \ZigG{  
//if(count>4) BP,"vq$'+  
// siteStop(); X~sl5?  
} I0(BKMp&  
pB&3JmgR$)  
d `>M-:dF  
System.err.println("文件下载结束！"); efy65+~GG  
} >zFe)  
catch(Exception e){e.printStackTrace ();} `g<@F^x5  
} 7u6o~(  
Ha1E /b]K  
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//获得文件长度 VtUe$ft  
public long getFileSize() Y _m4:9p  
{ P\tP0+at  
int nFileLength = -1; dD?1te  
try{ ';hU&D;s  
URL url = new URL(siteInfoBean.getSSiteURL()); lt|\$Iy(  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |o6 h:g  
httpConnection.setRequestProperty("User-Agent","NetFox"); BDNn~aU#m  
P_B#  
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int responseCode=httpConnection.getResponseCode(); 4[ M!x  
if(responseCode>=400) ,G!M?@Q  
{ AMG}'P:  
processErrorCode(responseCode); K19/M1~  
return -2; //-2 represent access is error jA$g0>  
} ,aeQXI#@  
~YA* RCe  
.X\p;~H 5  
String sHeader; mp!KPw08':  
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for(int i=1;;i++) '3 w=D )  
{ = I,O+^  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); L3JFQc/oh~  
//Utility.log(in.readLine()); KtchKpv  
sHeader=httpConnection.getHeaderFieldKey(i); "+/%s#&  
if(sHeader!=null) y >r7(qg  
{ ;,[6 n|M  
if(sHeader.equals("Content-Length")) GwQW I]  
{ }l~|c{WH`  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ye:pGa w  
break; e:fp8 k<  
} (+68s9XS7  
} 26PUO$&b.  
else 4z#{nZG  
break; .<
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} C,~wmS )@  
} :i_818h!?[  
catch(IOException e){e.printStackTrace ();} u\wdb^8ds  
catch(Exception e){e.printStackTrace ();} wwrP7T+d  
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Utility.log(nFileLength); 6w(Mb~[n  
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return nFileLength; x=T`i-M  
} :Rv?>I j  
d~F`q7F'?]  
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//保存下载信息（文件指针位置） RO[Ko-m|/N  
private void write_nPos() J ^gtSn^  
{ HM57b>
6  
try{ 1+6:K._C(m  
output = new DataOutputStream(new FileOutputStream(tmpFile)); JTK>[|c9oE  
output.writeInt(nStartPos.length); *p:`F:  
for(int i=0;i<nStartPos.length;i++) .Uq?SmK  
{ b~X^vXIv%%  
// output.writeLong(nPos); e8g"QDc  
output.writeLong(fileSplitterFetch.nStartPos); Lh3>xZy"-z  
output.writeLong(fileSplitterFetch.nEndPos); `Fa49B|`D  
} g
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output.close(); 1{l18B`  
} cKuU#&FaV  
catch(IOException e){e.printStackTrace ();} kR$>G2$!  
catch(Exception e){e.printStackTrace ();} Wt5x*p-!C  
} 0zm)M
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//读取保存的下载信息（文件指针位置） ie|I*;#  
private void read_nPos() fHhm)T8KB  
{ Atl`J.;G  
try{ :W]?6=  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); aEU[k>&  
int nCount = input.readInt(); ]@X5'r"  
nStartPos = new long[nCount]; z@;]Hy  
nEndPos = new long[nCount]; W%LTcm  
for(int i=0;i<nStartPos.length;i++) ?&;d#z*4  
{ *z[G+JX  
nStartPos = input.readLong(); XndGe=O  
nEndPos = input.readLong(); >2h|$6iWP  
} X8~dFjhX  
input.close(); *uHL'Pe;m  
} rt">xVl  
catch(IOException e){e.printStackTrace ();} -YM#.lQ  
catch(Exception e){e.printStackTrace ();} )
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} ?xEQ'(UBQ  
/~3~Xc~=p  
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private void processErrorCode(int nErrorCode) Y.` {]rC  
{ Y<|!)JLB2  
System.err.println("Error Code : " + nErrorCode); S\fEV"  
} 3sG7G:4  

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Fe 3*pUt  
//停止文件下载 }L Q9db1  
public void siteStop() /2}o:vLj  
{ Q#C;4)e  
bStop = true; _y#omEx  
for(int i=0;i<nStartPos.length;i++) r~cmrLQa  
fileSplitterFetch.splitterStop(); #qkokV6`  
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} lv -z[  
} 1d/-SxhZ  
//负责部分文件的抓取 K&FGTS,  
**FileSplitterFetch.java i0F.c\  
*/ [h
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package NetFox; <$\vL  
s ^NO(  
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import java.io.*; FTM(y CN  
import java.net.*; Jf\lnJTyU8  
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public class FileSplitterFetch extends Thread { W:Rs 0O  
@L^Fz$S
x  
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String sURL; //File URL <viIpz2jh%  
long nStartPos; //File Snippet Start Position u@|izRk  
long nEndPos; //File Snippet End Position aE}1~`  
int nThreadID; //Thread's ID u\YH,  
boolean bDownOver = false; //Downing is over  V|=PaO  
boolean bStop = false; //Stop identical B$~oZ'4v  
FileAccessI fileAccessI = null; //File Access interface whb|

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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException z;1y7W!v  
{ =Y`P}vI]w%  
this.sURL = sURL; Rz}?@zh_8  
this.nStartPos = nStart; n}==
 
this.nEndPos = nEnd; \PS{/XK  
nThreadID = id; M99#\0=/  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ^l1tQnj)7  
} =H*}{'#  
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public void run() ( Lj{V}^  
{ \)'nxFKqV  
while(nStartPos < nEndPos && !bStop) `|K,E  
{ b?Wg|D  
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try{ %M8Egr2|0  
URL url = new URL(sURL); a%*l]S0z"  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~ILig}I  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;9r Z{'i+|  
String sProperty = "bytes="+nStartPos+"-";   Q(SVJ  
httpConnection.setRequestProperty("RANGE",sProperty); 1xK'1g72  
Utility.log(sProperty); xt]Z{:.  
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InputStream input = httpConnection.getInputStream(); l@`D;m  
//logResponseHead(httpConnection); MWf]U  
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byte[] b = new byte[1024]; 1|Y(XB^os(  
int nRead; w+VeT@  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 8+vZ9!7  
{ L'{;V\d  
nStartPos += fileAccessI.write(b,0,nRead); 'Z2:u!E  
//if(nThreadID == 1) Dd|}LV  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); g-'y_'%0G  
} zx^]3}  
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Utility.log("Thread " + nThreadID + " is over!"); }aYm86C]  
bDownOver = true; 9@AGx<S1  
//nPos = fileAccessI.write (b,0,nRead); %VYQz)yW  
} ToNi<~  
catch(Exception e){e.printStackTrace ();} 8?] :>  
} '$Jt
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} eydVWVN  
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//打印回应的头信息 }_XW?^/8  
public void logResponseHead(HttpURLConnection con) 3WyK!@{  
{ j&E4|g (  
for(int i=1;;i++) 5@c,iU-L  
{ zi:F/TlUC  
String header=con.getHeaderFieldKey(i); bb;fV  
if(header!=null) mY-Z$8r  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); KtJE  
Utility.log(header+" : "+con.getHeaderField(header)); ZWMX!>o<  
else WrbDB-uM  
break; O$x-&pW`g  
} 8o8FL~&]  
} m^zx&  
m}.ru)^p  
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public void splitterStop() /R#-mY  
{ }yqRz6=YB  
bStop = true; J#*Uf>5NY  
} `7jm 
 
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} >7!aZO  
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/* rh2pVDS  
**FileAccess.java IWu^a w  
*//文件访问(定位，写) Ff>Y<7CQ v  
package NetFox; pH#&B_S6z=  
import java.io.*; b qB[vPsI  
R7*Jb-;$!  
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public class FileAccessI implements Serializable{ Qv8#{y@U  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ?>MD/l(l  
RandomAccessFile oSavedFile; DHpU?;|3  
long nPos; m6V
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^ vI|  
public FileAccessI() throws IOException R+]p -NI^  
{ D,xWc|V  
this("",0); qt]QO1pAd  
} v,vTRrpK  
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public FileAccessI(String sName,long nPos) throws IOException f[7'kv5S  
{ L:YsAv  
oSavedFile = new RandomAccessFile(sName,"rw"); OfTcF_%  
this.nPos = nPos; 1E$
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oSavedFile.seek(nPos); 7qE V5!  
} q<>2}[W  
{%D "0*^  
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public synchronized int write(byte[] b,int nStart,int nLen) 'G(N,vu[@  
{ ?f']*pD8  
int n = -1; Qm`f5
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try{ `m<="No  
oSavedFile.write(b,nStart,nLen); O
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n = nLen; x|0Q\<mEe  
} #!#V!^ o  
catch(IOException e) SJU93n"G/  
{ $pk3d+0B  
e.printStackTrace (); BT>*xZLpS  
} n_Um)GI>  
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D\({]oj]  
return n; pE `Q4:<A  
} "]c:V4S#`A  
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} w41#?VC/  
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]?``*{Zqy  
/* !FHNKh  
**SiteInfoBean.java ^|\ *i  
*/ Br#]FB|
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package NetFox; Y2<#%@%4  
Fg#*rzA  
}d.R=A9L
 
public class SiteInfoBean { S<p "k]  
,?&hqM\  
AZl=w`;/O%  
private String sSiteURL; //Site's URL $ya#-pi`;  
private String sFilePath; //Saved File's Path ;uoH+`pf  
private String sFileName; //Saved File's Name z[t$[Qg
 
private int nSplitter; //Count of Splited Downloading File /c'#+!19  
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public SiteInfoBean() ?Fi-,4  
{//nSplitter的缺省值为5 ' J-(v  
//default value of nSplitter is 5 :hMuxHr  
this("","","",5); 
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} 8l='Hl  
#G*z{BRQ  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) k ,<L#?,a  
{ PI{sO |  
sSiteURL= sURL; a[(n91J0  
sFilePath = sPath; k.lnG5e  
sFileName = sName; mD)N
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this.nSplitter = nSpiltter; E#HO0]S  
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} /@wm?ft6Gk  
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public String getSSiteURL() x7NxHTL  
{ RIJBHOa  
return sSiteURL; q!AS}rV  
} |xf%1(Rl@  
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public void setSSiteURL(String value) N}dJ)<(2~  
{ pg>P]a{  
sSiteURL = value; -9aht}Z  
} 'm2,7]  
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public String getSFilePath() S>"dUM  
{ s#d# *pgzh  
return sFilePath; 5X`.2q=d  
} 7PisX!c,h  
C&5T;=<jKO  
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public void setSFilePath(String value) @{
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{ Vm6^'1CY  
sFilePath = value; u*9C(je  
} }XXE hOO  
k"sL.}$  
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public String getSFileName() c3 wu&*p{  
{ tXp)o>"  
return sFileName; 2XI%4  
} SA/0Z=  
,U2D&{@  
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public void setSFileName(String value) gf3/kll9  
{ ]7VK&YfN  
sFileName = value; xeHu-J!P  
} ?&X6VNbU  
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public int getNSplitter() NKB!
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{ HFDg@@
 
return nSplitter; ]3I_H+hU  
} N9*$'  
xv%}xeEV  
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public void setNSplitter(int nCount) k[zf`x^  
{ ?.Kl/8ml  
nSplitter = nCount; >eEf|tKO  
} 4o=G) KO{  
} X'u`\<&W  
|BW956fBU  
}YSH8d  
/* L`Ic0}|lzy  
**Utility.java Z7f~|}  
*/ d@l;dos),  
package NetFox; CjST*(,b  
<y'ttxeS  
Fj&vWj`*  
public class Utility { %(e=Q^=  
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Ec[:6}  
public Utility() 6@$[x* V  
{ ' 5Ieqpm9  
au7BqV!uL  
{Ise (>V  
} \agC Q&  
?3|ZS8y  
//线程睡眠 eU12*(  
public static void sleep(int nSecond) )l"0:1Ig  
{ S4(IYnwN  
try{ S_QDYnF)`  
Thread.sleep(nSecond); t^[{8,N  
} 2`},;i~[  
catch(Exception e) bc"{ZL!C  
{ zH_q6@4  
e.printStackTrace (); NKGCz|- 9  
} D H.ljGb  
} 3dM6zOK
  
2MC\~"
L<  
//日志 81n%2G  
public static void log(String sMsg) TcIUo!:z  
{ P*LcWrK  
System.err.println(sMsg); dqkkA/1  
} Y9%yjh  

8jZYy!  
$wN.~"T  
public static void log(int sMsg) )N=wJN1  
{ ^*r${Nj  
System.err.println(sMsg); Oh^X^*I$@  
} 8%NX)hZyq}  
} q"cFw${  
|z4/4Y@  
H}@|ucM"\  
/* 2KG j !w  
**TestMethod.java p<+]+,|\~:  
*/ f*I5m=  
package NetFox; tyDtwV|  
)CmuC@ Q"  
-`;8~wMN  
public class TestMethod { ZN)/doK  
SB;Wa%  
y, Z
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public TestMethod() =#u2Rx%V  
{ ///xx/weblogic60b2_win.exe h1Lp:@:|  
try{ \uYUX~}i"  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); >hhd9  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); < d]|5  
SiteFileFetch fileFetch = new SiteFileFetch(bean); r" D|1  
fileFetch.start(); 2iGRw4`_a  
} p"JSYF 9]  
catch(Exception e){e.printStackTrace ();} EW!$D  
A
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dnx}c4P  
} GGBe/X  
a~%ej.)l  
_c&*'IY[V  
public static void main(String[] args) 4EpzCaEZ  
{ Za} |Ee  
new TestMethod(); m^=, RfUUd  
}  Ntqc=z  
} 7Y)wu$!7}  
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