http断点续传简单实现（java)

/* 2sT\+C&H  
**SiteFileFetch.java h=ko_/<  
*/ ^1[u'DW4  
package NetFox; 6 kAXE\T  
import java.io.*; s!/Q>A  
import java.net.*; fMRMQR=6B  
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public class SiteFileFetch extends Thread { o,=dm@j  
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SiteInfoBean siteInfoBean = null; //文件信息Bean e}W|wJ):j@  
long[] nStartPos; //开始位置 6ieP` bct  
long[] nEndPos; //结束位置 'E#Bz"
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 -2*Pm1\Z  
long nFileLength; //文件长度 qbQH1<yS<  
boolean bFirst = true; //是否第一次取文件 ~*ll,<L:  
boolean bStop = false; //停止标志 l%MIna/Tp  
File tmpFile; //文件下载的临时信息
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DataOutputStream output; //输出到文件的输出流 [!b=A:@  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） gJu
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public SiteFileFetch(SiteInfoBean bean) throws IOException %weG}gCM  
{ RL1cx|  
siteInfoBean = bean;  8=j_~&*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); |kkg1M#  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); A$o?_  
if(tmpFile.exists ()) &13#/  
{ 1WLaJ%Fv  
bFirst = false; :%"$8o*0W  
read_nPos(); psE&Rx3)  
} 2k"!o~s^  
else VAZ6;3@cd  
{ "TePO7^m  
nStartPos = new long[bean.getNSplitter()]; SFa~j)9'n  
nEndPos = new long[bean.getNSplitter()]; kV+O|9  
} +[$ Q C*  
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} @(LEuYq}  
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public void run()  .'^Pg  
{ /FA0(< -}  
//获得文件长度 KJN{p~Q  
//分割文件 ER*Et+>  
//实例FileSplitterFetch `'M}.q,k~  
//启动FileSplitterFetch线程 S%k](\7!  
//等待子线程返回 Ce_
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try{ B&c*KaK;~  
if(bFirst) D$G:#z*  
{ R(N5K4J  
nFileLength = getFileSize(); X2hyxTOp  
if(nFileLength == -1) fkK42*U@r  
{ 84u%_4/  
System.err.println("File Length is not known!"); P+[\9Gg  
} 8iwqy0<  
else if(nFileLength == -2) tJ!s/|u(  
{ ld/\`s[i  
System.err.println("File is not access!"); 1<d|@9?9`  
} 7.`:Z_  
else fs wQ*  
{ q~*>
 
for(int i=0;i<nStartPos.length;i++) ;]xJC j  
{ uj9IK  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ) v^;"q"  
} 0'4V*Y  
for(int i=0;i<nEndPos.length-1;i++) Uk|(VR9  
{ \dw*yZ^  
nEndPos = nStartPos[i+1]; zeG_H}[2&  
} D "9Hv3  
nEndPos[nEndPos.length-1] = nFileLength; b(|1DE0Cv  
} i$!-mYi+Q!  
} kA%"-$3  
CP!>V:w%9!  
c@~j}(A  
//启动子线程 E8s&.:;+  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; *FrlzIAom  
for(int i=0;i<nStartPos.length;i++) yUzpl[*e^o  
{ 1lLL9l{UVw  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), RkuPMs Hw;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), U k*HRudt  
nStartPos,nEndPos,i); E;Sb e9]   
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); vTY+J$N__  
fileSplitterFetch.start(); ffqz :6  
} S8$kxQg  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), p?,:  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); R#UcwX}o  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ?go+oS^  
nEndPos = " + nFileLength); yDW$v/j.|  
// fileSplitterFetch[nPos.length-1].start(); S.X*)CBB  
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bI?YNt,  
//等待子线程结束 1rmK#ld"=Z  
//int count = 0; m}dO\;  
//是否结束while循环 !R.*Vn[  
boolean breakWhile = false; cy-Bhk0H  
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while(!bStop) ypK1 sw  
{ Apx
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write_nPos(); i-`n5,  
Utility.sleep(500); R<jt$--H  
breakWhile = true; |p"E0av  
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for(int i=0;i<nStartPos.length;i++) J` J^C  
{ kt*""&R  
if(!fileSplitterFetch.bDownOver)
 8DsXw@o  
{ _H+|Ic  
breakWhile = false; 5VG[FY6Pl  
break; g-Y2U}&  
} Zw`vPvb!  
} ;>duY\$<  
if(breakWhile) 8NRc+@f|m  
break; 7jL3mI;n%;  
3j iSvrfI  

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//count++; ;P#c!  
//if(count>4) xbv  
// siteStop(); 5_MqpCL  
} \Gk4J<  
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System.err.println("文件下载结束！"); TsB"<6@!AA  
} Y]SX2kk(2  
catch(Exception e){e.printStackTrace ();} ~Yw`w2  
} *$I5_A8,.  
D+ )R_  
=
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//获得文件长度 (ugB3o  
public long getFileSize() 4G4[IAu_  
{ :7w^2/ZGo  
int nFileLength = -1; }(/")i4h  
try{ 30fsVwE2  
URL url = new URL(siteInfoBean.getSSiteURL()); Ikn)XZU^  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); [?vn>  
httpConnection.setRequestProperty("User-Agent","NetFox"); 7z=zJ4C  
i]@QxzCSF  
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int responseCode=httpConnection.getResponseCode(); g{}{gBplnl  
if(responseCode>=400) 1b,,uI_  
{ cx(aMcX6  
processErrorCode(responseCode); nf7l}^/UE  
return -2; //-2 represent access is error lStYfO:<'v  
} JQhw>H9&  
"|6#n34  
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String sHeader; ^" EsBt  
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for(int i=1;;i++) 5ZRO{rf  
{
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); I-
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//Utility.log(in.readLine()); .9< i  
sHeader=httpConnection.getHeaderFieldKey(i); &F*L=Ng  
if(sHeader!=null) LXIQpD,M  
{ J4I
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if(sHeader.equals("Content-Length")) 4nfpPNt  
{ 5jTBPct   
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 'ow`ej  
break; B4yC"55  
} /=5YHq>  
} 8KQ]3Z9

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else us2X:X)  
break; o<hT/ P  
} u7oHqo`  
} {p{TG5rwX  
catch(IOException e){e.printStackTrace ();} G8y:f%I!b  
catch(Exception e){e.printStackTrace ();} QeK@++EVc  
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Utility.log(nFileLength); Q!%4Iq%jr  
:
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return nFileLength; b
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} $rAHtr  
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//保存下载信息（文件指针位置） oQ!56\R  
private void write_nPos() *vL2n>HH  
{ &vf%E@<  
try{ GvL)SVv?  
output = new DataOutputStream(new FileOutputStream(tmpFile)); _k0X)N+li  
output.writeInt(nStartPos.length); q"|,HpQ  
for(int i=0;i<nStartPos.length;i++) t4a/\{/#9|  
{ #+vIq?  
// output.writeLong(nPos); oA^aT:o +  
output.writeLong(fileSplitterFetch.nStartPos); t(O{IUYM  
output.writeLong(fileSplitterFetch.nEndPos); `kn 'RZR  
} 6/m|Sg.m  
output.close(); (~R[K,G  
} MT8BP)C  
catch(IOException e){e.printStackTrace ();} x-Kq=LFy.  
catch(Exception e){e.printStackTrace ();} [Ch)6p  
} ^ di[J^  
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//读取保存的下载信息（文件指针位置） u}eqU%  
private void read_nPos() y5d=r]_S:  
{ HAHv^  
try{ IA\CBwiLj  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Mpf
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int nCount = input.readInt(); \
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nStartPos = new long[nCount]; S1iF1X(+?X  
nEndPos = new long[nCount]; hPs7mnSW  
for(int i=0;i<nStartPos.length;i++) _B@=fY(g!  
{ g:l5,j.K  
nStartPos = input.readLong(); )%4%Uo_Xm  
nEndPos = input.readLong(); 6*] g)m  
} HC4vet  
input.close(); "k)}qI{  
} Osb#<
9{}  
catch(IOException e){e.printStackTrace ();} h&$7^P  
catch(Exception e){e.printStackTrace ();} }r}$8M+1  
} }tvLe3O  
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private void processErrorCode(int nErrorCode) }9&Z#1/  
{ @a08*"lbp  
System.err.println("Error Code : " + nErrorCode); G@YX8!wU  
} V &K:~[M  
jE /pba4R  
xWwQm'I2}  
//停止文件下载 or?@Ti;  
public void siteStop() f^P:eBgpx  
{ _Eus<
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bStop = true; 82S?@%}#J  
for(int i=0;i<nStartPos.length;i++) e)pQh&uD  
fileSplitterFetch.splitterStop(); y4%u</  
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} pzX684  
} OLThi[Yn  
//负责部分文件的抓取 |v,5s=}7  
**FileSplitterFetch.java O5:?nD  
*/ 5pJ)OX  
package NetFox; n"[VM=YGI  
334UMH__  
y\=(;]S'  
import java.io.*; V'kCd4  
import java.net.*; D(EY"s37  
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public class FileSplitterFetch extends Thread { ^ :%"Z&  
-Wp69DP6q  
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String sURL; //File URL ^Z?X\t  
long nStartPos; //File Snippet Start Position 4NY00d/R  
long nEndPos; //File Snippet End Position 8db J'  
int nThreadID; //Thread's ID @8IYJ{=  
boolean bDownOver = false; //Downing is over K+9oV[DMs  
boolean bStop = false; //Stop identical (7C&I-l  
FileAccessI fileAccessI = null; //File Access interface ZG=B'4W  
X67.%>#3  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException _R&}CP  
{ !ke_?+8sY  
this.sURL = sURL;
wzLR]<6G  
this.nStartPos = nStart; v35wlt^}  
this.nEndPos = nEnd; wYZ"fusT  
nThreadID = id; N|Cx";,|FZ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 <AZ21"oR/  
} ~VNN  
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public void run() [x`trypg  
{
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while(nStartPos < nEndPos && !bStop) ttEQgkd`  
{ Z3:M%)e_u$  
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try{ SfKm]Z>Hp  
URL url = new URL(sURL); 3|$>2IRq  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); .rfufx9Sw  
httpConnection.setRequestProperty("User-Agent","NetFox"); {fkW0VB;  
String sProperty = "bytes="+nStartPos+"-"; HK@LA3  
httpConnection.setRequestProperty("RANGE",sProperty); -7GF2 @  
Utility.log(sProperty); RR2Q  
+UzFHiGy#  
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InputStream input = httpConnection.getInputStream(); Mx?{[zT"  
//logResponseHead(httpConnection); Sq9I]A  
\/rK0|2A  
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byte[] b = new byte[1024];
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int nRead; F
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 7qfo%n"  
{ w28!Yj1Q  
nStartPos += fileAccessI.write(b,0,nRead); NGl/F{<  
//if(nThreadID == 1) ,2Y PD4  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); fz%I'
+!  
} 
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%bM^/7  
]=2wQ8  
Utility.log("Thread " + nThreadID + " is over!"); QPe+K61U  
bDownOver = true; _%g}d/v}pO  
//nPos = fileAccessI.write (b,0,nRead); UQGOCP_  
}
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catch(Exception e){e.printStackTrace ();} Kjbz\~  
} y`"~zq0D  
} 6S-1Wc4  
X#l]%
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//打印回应的头信息 8no_xFA  
public void logResponseHead(HttpURLConnection con) F_8nxQ-  
{ .#"O VI]#  
for(int i=1;;i++) +Eil:Jz  
{ I]
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String header=con.getHeaderFieldKey(i); +r7uIwi$@  
if(header!=null) |ITSd%`3_  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); z^s40707x  
Utility.log(header+" : "+con.getHeaderField(header)); }-3| v<d  
else mQRQ2SN6  
break; C-@  
} -4P2 2  
} Evd
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}}a<!L,{  
public void splitterStop() @\[UZVmBw  
{ "%O,*t  
bStop = true; w(w%~;\kLP  
} d4"KM+EP?  

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} kyQUaFG  
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/* xrbDqA.b  
**FileAccess.java [aM_.[bf  
*//文件访问(定位，写) AXBv']Y  
package NetFox; \cq gCab/2  
import java.io.*; 3nfw:.  
5pNbO[  
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public class FileAccessI implements Serializable{ 
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0 S3~IeJ  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Ndj9B|s_  
RandomAccessFile oSavedFile;
7g(,$5  
long nPos; ;6N@raP7  
?!H<V@a  
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public FileAccessI() throws IOException &FrW(>2  
{ ;IhkGPpWP  
this("",0); Fs q=u-= :  
} QJFx/zU  
6&(gp(F  
hJ8|KPgdw  
public FileAccessI(String sName,long nPos) throws IOException Vq`i.>%5  
{ ien >Ou  
oSavedFile = new RandomAccessFile(sName,"rw"); ayfZ>x{s*  
this.nPos = nPos; o'.6gZ gk  
oSavedFile.seek(nPos); *&X.  
} #4h_(Y  
!:Lb^C;/  
1x+YgL5  
public synchronized int write(byte[] b,int nStart,int nLen) :0BaEqX  
{ 1Yt;1k'  
int n = -1; h,Y MR3:X  
try{ L]{ 1"`#  
oSavedFile.write(b,nStart,nLen); A8JEig 3Ix  
n = nLen; 7p""5hw  
} 6[BQx)7T  
catch(IOException e) `Q!|/B  
{ ;^)(q<]  
e.printStackTrace (); 5m")GWQaP@  
} p#}38`  
l[]K5?AS>-  
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return n; @F_#d)+%>  
} RYMOLX84  
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} 5q[0;`J  
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2Up1 FFRx  
/* ;$W/le"Xr  
**SiteInfoBean.java +O23@G?
x  
*/ '>(R'g42n  
package NetFox; Mf0g)X}1  
T:Dp+m!\{  
]saf<?fzr  
public class SiteInfoBean { mLM$dk3  
7*5$=z4,1  
gx&BzODPd0  
private String sSiteURL; //Site's URL 620y[iiK$  
private String sFilePath; //Saved File's Path />fy@nPl|  
private String sFileName; //Saved File's Name )%8oE3O#  
private int nSplitter; //Count of Splited Downloading File VXvr`U\  
;i`X&[y;  
!
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public SiteInfoBean() :<d\//5<9  
{//nSplitter的缺省值为5 =LJc8@<:f  
//default value of nSplitter is 5 rkA0v-N6v  
this("","","",5); d>:(>@wz  
} &F"Mkyf  
Y
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 4%O*2JAw  
{ lp5`Kw\  
sSiteURL= sURL; Fz7(Kuc  
sFilePath = sPath; #ej^K |Qx  
sFileName = sName; FKflN  
this.nSplitter = nSpiltter; yn<z!z%mz  
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} KU[eY}   
6~\z]LZ  
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public String getSSiteURL() <by}/lF0  
{ o[*</A }  
return sSiteURL; '2=u<
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} O4FW/)gq  
'>> IMF  
%7BVJJp2  
public void setSSiteURL(String value) QZk:G+$  
{ vTYI ez`g  
sSiteURL = value; yv4ki5u`  
} +]Of f^s  
+=%13cA*U  
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public String getSFilePath() .['@:}$1  
{ [6qa"I
e  
return sFilePath; ~T<#HSR`  
} HGmgQ>q@M$  
s)<#a(!  
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public void setSFilePath(String value) x Yr-,$/  
{ {e[S?1t=l  
sFilePath = value; l(9$s4R  
} cH6ie?KvAo  
jJl6H~ "q  
9BB<. p  
public String getSFileName() hi,!  
{ -i|qk`Y  
return sFileName; >%+"-bY  
} ]aq!@rDX  
wJh|$Vn  
sd
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public void setSFileName(String value) W<TW6_*e  
{ +4ax~fuU  
sFileName = value; UiS9u
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} 8WV1OIL  
a8aEZ724  
qVC_K/w 7  
public int getNSplitter() boo,KhW'Y  
{
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return nSplitter; a&)0_i:r  
} Pgg6(O9}B^  
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public void setNSplitter(int nCount) ` =dD6r  
{ PaV[{CD  
nSplitter = nCount; &oiX/UaY  
} @Fqh]1t  
} rq9{m(
  
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/* 'P}"ZHW  
**Utility.java +V1EqC*  
*/ 8YraW|H  
package NetFox; n1o/-UY  
<Hhl=6op  
k(o[T),_%0  
public class Utility { )gV+BHK  
\(.&E`r  
uOc>~ITPS  
public Utility() MQE=8\  
{ ,T"pUeVJ  
]P$8# HiX  
'Z'X`_  
} oT&JQ,i[2Q  
Y32F{ z  
//线程睡眠 ]>/YU*\  
public static void sleep(int nSecond) !`\W8JT+  
{ Dqe)8 r  
try{ ?LgR8/Io@5  
Thread.sleep(nSecond); l9)iLOj  
}
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catch(Exception e) ~j3B'  
{ Yqm
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e.printStackTrace (); #NNj#  
} >joGGT  
} O;f^'N  
4C[,S|J  
//日志 L@S"c (  
public static void log(String sMsg) 2*n2!7jZ*  
{ - t4"BD  
System.err.println(sMsg); :q~qRRmjBe  
} "$+naY{w  
'0X!_w6W  
Ql%7wrK  
public static void log(int sMsg) +@]1!|@(  
{ n<8$_?-
 
System.err.println(sMsg); mLk@&WxG  
} H#k"[eZ  
} 9 f-T>}  
swG^L$r`  
xj{X#[q):  
/* "Na9Xea  
**TestMethod.java O 4N_lr~  
*/ riZFcV
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package NetFox; G6JyAC
9j  
Q'JEDH\  
Q6,rY(b6  
public class TestMethod { ]?-56c,  
T =3te|fv  
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public TestMethod() C-qsyJgZy  
{ ///xx/weblogic60b2_win.exe h@Ea$1'e,  
try{
dVVeH\o  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); b-]E-$Uz  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Jkpw8E7  
SiteFileFetch fileFetch = new SiteFileFetch(bean); @<CJbFgJp  
fileFetch.start(); <Xp F  
} i0-!!  
catch(Exception e){e.printStackTrace ();} rRcfZZ~` M  
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} -_uL;9r  
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public static void main(String[] args) z"}k\B-5  
{ #H O\I7m  
new TestMethod(); Q[J,j+f<  
} M42Zpb].  
} P:lvZ   
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