http断点续传简单实现（java)

/* Wcc4/:`Hu  
**SiteFileFetch.java CR23$<FC  
*/ L3HC-  
package NetFox; y+k^CT/u  
import java.io.*; P<Bx1H-z-  
import java.net.*; O>+=cg  
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public class SiteFileFetch extends Thread { k L6s49  
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SiteInfoBean siteInfoBean = null; //文件信息Bean (_4DZMf  
long[] nStartPos; //开始位置 C{m%]jKH  
long[] nEndPos; //结束位置 [u!n=ev  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 {|>Wwa2e  
long nFileLength; //文件长度 XQn1B3k+  
boolean bFirst = true; //是否第一次取文件 N,K/Ya)1  
boolean bStop = false; //停止标志 \8$~ i  
File tmpFile; //文件下载的临时信息 ;PC!  
DataOutputStream output; //输出到文件的输出流 "P#1=  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） J)n_u),  
public SiteFileFetch(SiteInfoBean bean) throws IOException UJh;Hp:  
{ BVeMV4  
siteInfoBean = bean; `dcz9 *  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); }R16WY_'  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ;6``t+]q   
if(tmpFile.exists ()) /;(ji?wN  
{ Ur]$@N  
bFirst = false; #0T/^ #  
read_nPos(); FHU6o910  
} L~t< 0\r  
else [5~mP`He  
{ ";=!PL  
nStartPos = new long[bean.getNSplitter()]; DqQp47kp  
nEndPos = new long[bean.getNSplitter()]; _rB,N#{2R=  
} -->0e{y  
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} 3%?t
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public void run() z
mip  
{ 4zS0kk;+  
//获得文件长度 ^K"BQ~-w  
//分割文件 $O*@Jg=  
//实例FileSplitterFetch cg3}33Z;6  
//启动FileSplitterFetch线程 $2h%IK>#G  
//等待子线程返回 }ww/e\|Nt=  
try{ Bz_'>6w  
if(bFirst) zsJ# CDm  
{ p" >*WQ   
nFileLength = getFileSize(); "."(<c/3  
if(nFileLength == -1) 0)Ephsw  
{ !Nx1I  
System.err.println("File Length is not known!"); SC~k4&xy  
} HQ-++;Q  
else if(nFileLength == -2) ecs 0iW-,  
{ +`GtZnt#  
System.err.println("File is not access!"); ,9bnR;f\  
} %\<b{x# G  
else kd^H}k  
{ B ktRA  
for(int i=0;i<nStartPos.length;i++) SdYf^@%}F  
{ ]7Vg9&1`  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ;9OhK71}  
} TC/c5:)]  
for(int i=0;i<nEndPos.length-1;i++) A_9^S!  
{ ]S&ki
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nEndPos = nStartPos[i+1]; S
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} -sQ[f18  
nEndPos[nEndPos.length-1] = nFileLength; *"w hup[  
} 4l  ZK@3  
} 0i_:J  
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//启动子线程 ia'z9  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Q"qI'*Kgt  
for(int i=0;i<nStartPos.length;i++)  viAAb  
{ yV8J-YdsG  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), L_!ShE
  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), oVy{~D=  
nStartPos,nEndPos,i); FoK2h
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); '3672wF/  
fileSplitterFetch.start(); V+Tv:a  
} j-ej7  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), NV4g5)D&L  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); tsc`u>  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", >l&]Ho  
nEndPos = " + nFileLength); Y'|,vG  
// fileSplitterFetch[nPos.length-1].start(); y+ze`pL?  
EpAgKzVpJ  
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//等待子线程结束 e7U\gtZ.  
//int count = 0; {zAI-?#*u  
//是否结束while循环 u)0I$Tc"  
boolean breakWhile = false; _h!.gZB3  
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while(!bStop) TsTc3  
{ b4_0XmL  
write_nPos(); |[>@Kk4  
Utility.sleep(500); \
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breakWhile = true; [Iks8ZWr_  
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for(int i=0;i<nStartPos.length;i++) tVn?cS  
{ |EE1S{!24m  
if(!fileSplitterFetch.bDownOver) 6^Wep- $  
{ &|>~7(
 
breakWhile = false; GF ux?8A:%  
break; |HK:\)L%  
} ZUQ _u  
} 4 ThFC  
if(breakWhile) ~w>h#{RB  
break; 1Nt &+o  
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//count++; !?>V^#c  
//if(count>4) }S/i3$F0~  
// siteStop(); "Q.*  
} |ri)-Bk ,  
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System.err.println("文件下载结束！"); 3%Y:+%VE  
} >7>I1  
catch(Exception e){e.printStackTrace ();} y+(\:;y$7  
}
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//获得文件长度 yn62NyK  
public long getFileSize() lgOAc,  
{ _>- D*l  
int nFileLength = -1; (9'^T.J  
try{ 7{|QkTgC  
URL url = new URL(siteInfoBean.getSSiteURL()); -* ,CMw  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); nYyhQX~]B  
httpConnection.setRequestProperty("User-Agent","NetFox"); @RoZd?  
^LMgOA(7  
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int responseCode=httpConnection.getResponseCode(); USBQEt  
if(responseCode>=400) TLdlPBnr8  
{ ote,`h  
processErrorCode(responseCode); Wgwd?@uK  
return -2; //-2 represent access is error =01X  
}
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String sHeader; W7>2&$
  
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for(int i=1;;i++) Gnkar[oa&  
{ .Nn11F< d  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 3z+l-QO8  
//Utility.log(in.readLine()); 6CY&pbR  
sHeader=httpConnection.getHeaderFieldKey(i); %=aKW[uq]  
if(sHeader!=null) XIW0Z C   
{ {D+mr[ %  
if(sHeader.equals("Content-Length")) oh9
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{ ?E([Nc0T  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); P\jGySj
  
break; JVE\{ e)  
} _wq?Pa<)e  
} " 9Gn/-V>  
else <S@jf4  
break; :?t~|7O:  
} 2c9?,Le/;  
} Gt`7i(  
catch(IOException e){e.printStackTrace ();} }s}g}t8v-  
catch(Exception e){e.printStackTrace ();} <)VgGjZ-H  

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Utility.log(nFileLength); y0* rY  
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return nFileLength; (`tRJWbdz  
} :L[>!~YG_n  
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//保存下载信息（文件指针位置） 2{OR#v~  
private void write_nPos() 
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{ /).{h'^Hq\  
try{ )kD
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output = new DataOutputStream(new FileOutputStream(tmpFile)); CKsV
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output.writeInt(nStartPos.length); -pC8
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for(int i=0;i<nStartPos.length;i++) h@:K=ggK  
{ Zj`WRH4  
// output.writeLong(nPos); :KLXrr  
output.writeLong(fileSplitterFetch.nStartPos); xA] L0h]  
output.writeLong(fileSplitterFetch.nEndPos); ]?Ef0?44  
} &gXh:
.  
output.close(); 4QL>LK  
} f[^f/jGm  
catch(IOException e){e.printStackTrace ();} K+B978XD  
catch(Exception e){e.printStackTrace ();} %Sr+D{B  
} 7},A.q  
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//读取保存的下载信息（文件指针位置） K@D\5s|1|  
private void read_nPos() zsFzg.$3&  
{ \/a6h   
try{ 6 63o  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); T{YZ`[  
int nCount = input.readInt(); J$dwy$n  
nStartPos = new long[nCount]; D Ez,u^  
nEndPos = new long[nCount]; 25^?|9o7  
for(int i=0;i<nStartPos.length;i++) bF'rK'',  
{ -fR:W{u  
nStartPos = input.readLong(); >| R'dF}  
nEndPos = input.readLong(); Wa_qD  
} YGp+[|'  
input.close(); tK#R`AQ  
} K5""%O+  
catch(IOException e){e.printStackTrace ();} :{lwz
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catch(Exception e){e.printStackTrace ();} JfY*#(
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} ZCiCZ)oc  
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private void processErrorCode(int nErrorCode) wQkM:=t5  
{ vvoxK0  
System.err.println("Error Code : " + nErrorCode); GD W@/oQr  
} N##`  
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//停止文件下载 MK$u}G  
public void siteStop() 'M90Yia  
{ sp9gz~Kq
 
bStop = true; J=4>zQ
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for(int i=0;i<nStartPos.length;i++) PNU(;&2<  
fileSplitterFetch.splitterStop(); E-e(K8R  
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} 5j%G7.S\  
} 6SSDc/  
//负责部分文件的抓取 \l%xuT  
**FileSplitterFetch.java n
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*/ 6*OL.~WE  
package NetFox; NkE0S`Xf  
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2G8pDvBr  
import java.io.*; e~'`x38  
import java.net.*; `?Rq44=  
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public class FileSplitterFetch extends Thread { H=t"qEp  
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String sURL; //File URL wb-yAQ8  
long nStartPos; //File Snippet Start Position 7*/{mK)  
long nEndPos; //File Snippet End Position 5=dL`  
int nThreadID; //Thread's ID
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boolean bDownOver = false; //Downing is over K|& f5w  
boolean bStop = false; //Stop identical
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FileAccessI fileAccessI = null; //File Access interface ?GhyVXS y.  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 9 _d2u#  
{ }x8!{Y#cF  
this.sURL = sURL; +Y\:Q<eMFg  
this.nStartPos = nStart; md!6@)S-p  
this.nEndPos = nEnd; _GOSqu!3Y  
nThreadID = id; J 3!~e+wn  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 H'+7z-%G  
} {4"V)9o-1>  
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public void run() u8e_Lqx?  
{ jm_-f  
while(nStartPos < nEndPos && !bStop) )P$(]{  
{ *bkb-nKw  
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try{ $YYWpeW '  
URL url = new URL(sURL); <hT\xBb:  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ^;C&  
httpConnection.setRequestProperty("User-Agent","NetFox"); g7oY
1;  
String sProperty = "bytes="+nStartPos+"-"; W
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httpConnection.setRequestProperty("RANGE",sProperty); '<Z[e`/  
Utility.log(sProperty); ^0VL](bD>  
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InputStream input = httpConnection.getInputStream(); pYO =pL^Q  
//logResponseHead(httpConnection); 'CLZ7pV  
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byte[] b = new byte[1024]; ]@q%d
sz  
int nRead; xNz(LZ.c  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) #-hO\ QdC  
{
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nStartPos += fileAccessI.write(b,0,nRead); >rG>Bz^Pu  
//if(nThreadID == 1) LQ0/oYmNc  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); yNu_>!Cp5  
} {.Tx70kn  
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Utility.log("Thread " + nThreadID + " is over!"); UD I{4+z  
bDownOver = true; n:j'0WW  
//nPos = fileAccessI.write (b,0,nRead); %>_[
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} GAGS-G#  
catch(Exception e){e.printStackTrace ();} tDByOml8Ix  
} -[>de! T3$  
} {C1crp>q  
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//打印回应的头信息 lU WXXuO]  
public void logResponseHead(HttpURLConnection con) -@TY8#O#-  
{ -@To<<`n  
for(int i=1;;i++) *4,Q9K_  
{ .RQra+up  
String header=con.getHeaderFieldKey(i); RNIXQns-=S  
if(header!=null) jnH\}IB  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Xxq
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Utility.log(header+" : "+con.getHeaderField(header)); <}a?<):S  
else +X?ErQm  
break; ~ELY$G.xl  
} =w2 4(S  
} PK*Wu<<  
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public void splitterStop() A=|XlP$6  
{ 3^xUN|.F*V  
bStop = true; {I
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} J~~\0 u  
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} |OQ]F  
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/* ldv@C6+J  
**FileAccess.java L3&Ys3-h  
*//文件访问(定位，写) )XI[hVUA  
package NetFox; X1o",,N^M  
import java.io.*; 7*:zN
  
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public class FileAccessI implements Serializable{ /Vlc8G  
"~KDm(D  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 PN* .9;5Z  
RandomAccessFile oSavedFile; )ycI.[C  
long nPos; -H| 982=  
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public FileAccessI() throws IOException Mw[3711v  
{ j,n:%5P\v  
this("",0); Xfiwblg  
} ]HKt7 %,  
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public FileAccessI(String sName,long nPos) throws IOException a`O'ZY  
{ .jrNi=BP*  
oSavedFile = new RandomAccessFile(sName,"rw"); .#EU@Hc
  
this.nPos = nPos; \S}/2]* 1  
oSavedFile.seek(nPos); zAgX{$/Fg  
} Z0g
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;QI9OcE@/  
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public synchronized int write(byte[] b,int nStart,int nLen) wMa8HeBE\  
{ %ms%0%  
int n = -1; U-|]A\`)I  
try{ /VR~E'Cy%  
oSavedFile.write(b,nStart,nLen); g_>&
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n = nLen; y^2#;0W  
} qHt/,w='Q  
catch(IOException e) VKa+[  
{ *d._H1zT  
e.printStackTrace (); '%$Vmf)=  
} vPkLG*d8  
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return n; g*k)
ws  
} [ATJ! O  
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} OB>Hiy   
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/* eORXyh\K  
**SiteInfoBean.java k1&9 bgI  
*/ Ek+R  
package NetFox; s$Vl">9#  
Ni~IY# '  
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public class SiteInfoBean { $6"sRI6u  
9A|A@E#  
/=2aD5r  
private String sSiteURL; //Site's URL _p$/.~Xo9  
private String sFilePath; //Saved File's Path \o<ucp\J  
private String sFileName; //Saved File's Name 3,PR6a,b'  
private int nSplitter; //Count of Splited Downloading File mK:gj&N7X|  
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"  
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public SiteInfoBean() 0`/G(ukO  
{//nSplitter的缺省值为5 ,dC.|P' `  
//default value of nSplitter is 5 x $uhkP  
this("","","",5); ZTmy}@l  
} ljFq;!I5  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) x0j5D  
{ P&`%VW3E  
sSiteURL= sURL; N'{[BA(eE  
sFilePath = sPath; jY6GWsh:9  
sFileName = sName; (p]FI#y  
this.nSplitter = nSpiltter; ?Y"%BS+pt  
161P%sGx2  
,Ckcc  
} :7e*- '  
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public String getSSiteURL() WD5J2EePT  
{ (MGgr  
return sSiteURL; 7F<{ Qn  
} Hq.rG-,p  
eV7;#w<]  
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public void setSSiteURL(String value) gP_N|LuF"  
{  : (UK'i  
sSiteURL = value; uFr12ZFgK  
} 0/HFLz'  
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public String getSFilePath() v[L+PD U  
{ a (U52dO,  
return sFilePath; [?K>s>it  
} S:1[CNL;  
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public void setSFilePath(String value) 6Bq_<3P_  
{ 5CK+\MK  
sFilePath = value; A f'&, 1=q  
} ~5 6&!4  
)
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public String getSFileName() |[],z 8  
{ t/ \S9  
return sFileName; a1pp=3Pd?~  
} @$ 7 GrT  
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public void setSFileName(String value) ~'M<S=W  
{ =lAjQt
 
sFileName = value; IfmQPs+f  
} =g+}4P
 
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public int getNSplitter()  IuY9Q8  
{ |WB-Ng  
return nSplitter; ixA.b#!1  
} kk fWiPO^  
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n/KO{:  
public void setNSplitter(int nCount) (d4btcg
 
{ V]|X ,G  
nSplitter = nCount; y:)^*2GA-B  
} *JK0X  
} ]:e_Y,@  
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/* L:HvrB
~  
**Utility.java (zsG!v  
*/ J~%43!X\K  
package NetFox; m%0-3c(  
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public class Utility { ^E^`"  
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public Utility() :#:|:q.]  
{ MpOU>\  
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} 2E }vuw=c  
*2Pr1U  
//线程睡眠 3sr_V~cZ9  
public static void sleep(int nSecond) ||hQ*X<m>  
{  VAiJL  
try{ M5{#!d}^D  
Thread.sleep(nSecond); 1.14tS-}[4  
} +/[M Ex=   
catch(Exception e) !(lcUdBd  
{ Zv!`R($  
e.printStackTrace (); zRna=h!  
} P<g(i 6]  
} '=0}2sF>  
lcl|o3yQ  
//日志 y,5qY}P+  
public static void log(String sMsg) wPg/.N9H  
{ /\%<VBx ?q  
System.err.println(sMsg); rZ?:$],U!  
} JpS}X\]i  
7^><Vh"qV  

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public static void log(int sMsg) ET.jjV  
{ c)#P}Ai  
System.err.println(sMsg); X+!+&RAN*  
} JmCMFqB9  
} DFMpU.BN W  
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/* w(@r-2D"  
**TestMethod.java Jk*cuf`rq  
*/ @` KYgjjH  
package NetFox; ,
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l
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public class TestMethod { ;TL.QN/l  
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public TestMethod() x*Z'i<;B  
{ ///xx/weblogic60b2_win.exe `n$Ak5f  
try{ Z1 Nep!  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); u ON(LavB  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); s70Z&3A  
SiteFileFetch fileFetch = new SiteFileFetch(bean); wsmgkg  
fileFetch.start(); HAn{^8"@  
} -+"#G?g  
catch(Exception e){e.printStackTrace ();} B[Lm}B[  
]LB_ @#  
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} ~kZdep^]  
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M5n
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public static void main(String[] args) -+ByK#<%  
{ j !*,(  
new TestMethod(); [oh06_rB  
} Ic(qA{SM  
} `O6#-<>  
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