http断点续传简单实现（java)

/* 3S_H&>K  
**SiteFileFetch.java OHAU@*[lM  
*/ _Cz98VqRk  
package NetFox; D`G;C  
import java.io.*; N}nE9z5  
import java.net.*; .zdaY, U  
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public class SiteFileFetch extends Thread { {_
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 ]XlBV-@b  
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SiteInfoBean siteInfoBean = null; //文件信息Bean z0\ $#r^I  
long[] nStartPos; //开始位置 9C?SEbC  
long[] nEndPos; //结束位置 4=^Ha%l  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 'C7R* P  
long nFileLength; //文件长度 Q;>Yk_(S  
boolean bFirst = true; //是否第一次取文件 M]Vi]s  
boolean bStop = false; //停止标志 Tw$tE:  
File tmpFile; //文件下载的临时信息 V[%IU'{:  
DataOutputStream output; //输出到文件的输出流 o`QH8  
V!. Y M)B  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 5#|
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public SiteFileFetch(SiteInfoBean bean) throws IOException ddl]! ^IK  
{ Sx~mc_ekY  
siteInfoBean = bean; 8q]"CFpa  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); g*FHZM*N9  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); T[e+iv<8j
 
if(tmpFile.exists ()) }@ U}c6/  
{ f-i5tnh  
bFirst = false; rIB./,  
read_nPos(); T; [T`  
} 1jKj'7/K  
else 4IOqSB|  
{ @mu{*. &  
nStartPos = new long[bean.getNSplitter()]; cr0/.Zv)  
nEndPos = new long[bean.getNSplitter()]; !Y|xu07  
} -@w}}BR  
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} N@Ap|`Ei  
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public void run() s+ *LVfau  
{ ,'YKL",  
//获得文件长度 \cX9!lHl  
//分割文件 Y@UW\d*'%I  
//实例FileSplitterFetch OUN~7]OD%  
//启动FileSplitterFetch线程 t vW0 W  
//等待子线程返回 01 +#2~S  
try{ KDP&I J  
if(bFirst) n]w%bKc-9  
{ %2'4h(Oq^  
nFileLength = getFileSize(); ^f(El(w  
if(nFileLength == -1) M`=\ijUwN  
{ c?c"|.-<p  
System.err.println("File Length is not known!"); u@Ni *)p`  
} {<Y!'WL{  
else if(nFileLength == -2) b/T k$&  
{ eln$,zK/b  
System.err.println("File is not access!"); .}!.: |  
} ?a,`{1m0\  
else 0#Q]>V@rO4  
{ h3\(660>$  
for(int i=0;i<nStartPos.length;i++) meap;p  
{ VyIJ)F.c  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); A2PeI"y  
} $_a/!)bP  
for(int i=0;i<nEndPos.length-1;i++) \Yv44*I`  
{ Bbb":c6w0  
nEndPos = nStartPos[i+1]; 3$_- 0>  
} 1csbuR?  
nEndPos[nEndPos.length-1] = nFileLength; F5UHkv"K&O  
} u1z!OofN>  
} HyQ(9cn|  

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//启动子线程 VqOTrB1w/  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; L&5zr_  
for(int i=0;i<nStartPos.length;i++) h,fahbH-  
{ `B3YP1  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 2of+KI:
 
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 54s90  
nStartPos,nEndPos,i); &MrG ,/  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^d9o \  
fileSplitterFetch.start(); p .~5k  
} zJ8jJFL+Y  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,>pv>)u{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); -HFyNk]>  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", --`W1!jI@  
nEndPos = " + nFileLength); J
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// fileSplitterFetch[nPos.length-1].start(); 8rz,MsFR  
jlD3SF~2  
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//等待子线程结束 s"wz !{G4  
//int count = 0; Pn}oSCo  
//是否结束while循环 kRiZ6mn  
boolean breakWhile = false; gX5.u9%C\  
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 t|:XSJ9  
while(!bStop) eoiC.$~\  
{ 8PRB_ny  
write_nPos(); ab_EH}j1\q  
Utility.sleep(500); c 8|&Q  
breakWhile = true; {\k:?w4  
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for(int i=0;i<nStartPos.length;i++) Y;sN UX  
{ 8{Wh4~|+  
if(!fileSplitterFetch.bDownOver) ~</H>Jd  
{ dM5N1$1,  
breakWhile = false; )x&>Cf<,  
break; pH?"@  
} 4?7OP t6  
} "3a_C,\  
if(breakWhile) *C^`+*}OE$  
break; _8?r!D#P;s  
s|Zv>Qt  
\XG\
 
//count++; "Ze<dB#,Y  
//if(count>4) Ni61o?]Nj  
// siteStop(); !r_2b! dy  
} fh}j)*K8  
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;c>IM]  
System.err.println("文件下载结束！"); VQ`a-DL  
} f(*^zga,  
catch(Exception e){e.printStackTrace ();} kM@heFJb.  
} P:HmT   
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8>V)SAI'  
//获得文件长度 J]4Uh_>)  
public long getFileSize() }JBLzk5|  
{ 5]@"f/  
int nFileLength = -1; X\LiV{c  
try{ =xsTVT;sj  
URL url = new URL(siteInfoBean.getSSiteURL()); AU^5N3%j  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Fop'm))C8  
httpConnection.setRequestProperty("User-Agent","NetFox"); p EbyQ[  
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int responseCode=httpConnection.getResponseCode(); 7 a_99?J  
if(responseCode>=400) I>z0)pB  
{ 5Qgh\4  
processErrorCode(responseCode); W%^;:YQ9i  
return -2; //-2 represent access is error
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} =GSe$f?  
{Zy)p%j8  
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String sHeader; K-drN)o  
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for(int i=1;;i++) nf9NJ_8}4H  
{ c0u1L@tj  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); %.VFj7J  
//Utility.log(in.readLine()); :f5"w+  
sHeader=httpConnection.getHeaderFieldKey(i);  a EmLf  
if(sHeader!=null) /#I~iYPe  
{ t bEJyA  
if(sHeader.equals("Content-Length")) C;NG#4;'  
{ xC+TO  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ct![eWsuB  
break; }IGoPCV|  
} j
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}
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else Tg~SGAc  
break; Pmj%QhOYE  
} +1=]93gP  
} 2Bg0 M  
catch(IOException e){e.printStackTrace ();} Y]6kA5  
catch(Exception e){e.printStackTrace ();} eT6T@C
](  
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Utility.log(nFileLength); 9S]]KEGn4  
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return nFileLength; jM!Q 04(  
} 3r-oZ8/n  
<P1yA>=3`  

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//保存下载信息（文件指针位置） 8%Hc%T[RnT  
private void write_nPos() ,37\8y?o\  
{ N-:.z]j#_  
try{ qz6@'1  
output = new DataOutputStream(new FileOutputStream(tmpFile)); K#!c<
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output.writeInt(nStartPos.length); 
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for(int i=0;i<nStartPos.length;i++) /Mmts=^Ja  
{ @pkQ2OM 2  
// output.writeLong(nPos); N>Q~WXvV#  
output.writeLong(fileSplitterFetch.nStartPos); JOFQyhY0>m  
output.writeLong(fileSplitterFetch.nEndPos); ^^Te  
} #)PAvBJ;m  
output.close(); >JckN4v  
} {~cM 6W]f  
catch(IOException e){e.printStackTrace ();} ,Vr-E  
catch(Exception e){e.printStackTrace ();} zqt{oN_  
} xfK@tLEZ-1  
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//读取保存的下载信息（文件指针位置） qbD>)}:1  
private void read_nPos() ykat0iqo  
{ ;Qq<5I"y  
try{ <<l1zEf@  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); >PmnR>x-rj  
int nCount = input.readInt(); S";c7s  
nStartPos = new long[nCount]; &f($= 68  
nEndPos = new long[nCount]; PJ3M,2H1b.  
for(int i=0;i<nStartPos.length;i++) :^H2D=z@  
{ vMYL( ]e  
nStartPos = input.readLong(); 5VZZk%oy  
nEndPos = input.readLong(); ~6Pv5DKq  
} 8$`$24Wx  
input.close(); A} v;uNS]  
} ^
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catch(IOException e){e.printStackTrace ();} u%sfHGrH  
catch(Exception e){e.printStackTrace ();} :`>bh  
} {j[a'Gb  
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oF
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private void processErrorCode(int nErrorCode) r@u8QhD  
{ i#bcjH  
System.err.println("Error Code : " + nErrorCode); 45A|KaVpg  
} gJBw6'Z  
<\`qRz0/  
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//停止文件下载 F_-}GN%  
public void siteStop() Xb2.t^ ]f  
{ ;:obg/;uJ  
bStop = true; Tnoy#w}Ve  
for(int i=0;i<nStartPos.length;i++) H[2W(q6  
fileSplitterFetch.splitterStop(); %Hu?syo  
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} P"f4`q  
} ,{2= nb[  
//负责部分文件的抓取 sWv!ig_  
**FileSplitterFetch.java keb.%cb=  
*/ 9%Qlg4~<s  
package NetFox; t$z 5m<8  
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import java.io.*; &oxHVZJ  
import java.net.*; ~$d(@T&  
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public class FileSplitterFetch extends Thread { g&I
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; ,n}>iTE  
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String sURL; //File URL {PKf]m  
long nStartPos; //File Snippet Start Position rT_J6F5J  
long nEndPos; //File Snippet End Position M$s9  
int nThreadID; //Thread's ID EGVS8YP>h  
boolean bDownOver = false; //Downing is over LK+67Y{25  
boolean bStop = false; //Stop identical @{{6Nd5  
FileAccessI fileAccessI = null; //File Access interface >S>B tRl  
tUi@'%>=5  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException moRo>bvN~  
{ ?7uK:'8  
this.sURL = sURL; J p)I9k,Ez  
this.nStartPos = nStart; *i>hFNLdOM  
this.nEndPos = nEnd; NA=m<n#  
nThreadID = id; 4*'ZabDD  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 J,:Wv`N:9~  
} 4s6,`-  
4JRQ=T|P7I  
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public void run() 08+\fT [  
{ 5,J.$Sax  
while(nStartPos < nEndPos && !bStop) bbT1p:RF  
{ M|fC2[]v B  
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try{ @MP;/o+  
URL url = new URL(sURL); 35JVF*z  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); p z\8Bp}yo  
httpConnection.setRequestProperty("User-Agent","NetFox"); k)9+;bKQQ  
String sProperty = "bytes="+nStartPos+"-"; 3  $a;  
httpConnection.setRequestProperty("RANGE",sProperty); 1`GW>ZKv  
Utility.log(sProperty); p<+Y;,+  
UCj{ &  
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InputStream input = httpConnection.getInputStream(); 57KrDxE}  
//logResponseHead(httpConnection); yz"hU  
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byte[] b = new byte[1024]; TE:|w Xe  
int nRead; kB.CeG]
tk  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 2!R+5^Iy  
{ PD~vq^@Q  
nStartPos += fileAccessI.write(b,0,nRead); s|I$c;>  
//if(nThreadID == 1) CEAmb[h  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); #v; :K8  
} =IKgi-l*  
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Utility.log("Thread " + nThreadID + " is over!"); 45k.U$<|  
bDownOver = true; <}T7;knO  
//nPos = fileAccessI.write (b,0,nRead); Yv.7-DHNl  
} Xl:.`{5L  
catch(Exception e){e.printStackTrace ();} a(kY,<}  
} v 6s]X*l?  
} Rg^ps  
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//打印回应的头信息 j2%fAs<  
public void logResponseHead(HttpURLConnection con) @}2EEo#  
{ e
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for(int i=1;;i++) gVrfZ&XF84  
{ !hjF"Pa  
String header=con.getHeaderFieldKey(i); KciN"g|X  
if(header!=null) |h&Z.  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); yb,X }"Et  
Utility.log(header+" : "+con.getHeaderField(header)); `{m,&[n  
else %j/pln&  
break; KcUR /o5K  
} X]o"4#CQIX  
} a?xZsR  
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dL_9/f4   
public void splitterStop() \_YDSmjy  
{ wbvOf X  
bStop = true; ksTK'7*  
} 4)8e0L*[B?  
HYL['B?Wid  
8/T,{J\  
} m2P&DdN[  
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/* GaV}@Q  
**FileAccess.java hxMV?\MYj  
*//文件访问(定位，写) |>O
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package NetFox; x4(8 =&Z  
import java.io.*; tfD7!N{  
v^)B[e!  
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public class FileAccessI implements Serializable{ _90<*{bt.  
i]OEhB Y  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 $E.Fgy:G  
RandomAccessFile oSavedFile; D)Ep!`Q   
long nPos; )U7fPKQ  
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public FileAccessI() throws IOException 8]oolA:^4s  
{ "0,FB4L[U5  
this("",0);
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} )
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public FileAccessI(String sName,long nPos) throws IOException d3Y;BxEz  
{ qWx{eRp d  
oSavedFile = new RandomAccessFile(sName,"rw"); ve:Oe{Ie{  
this.nPos = nPos; 8&nb@l  
oSavedFile.seek(nPos); I9Uj3cL\  
} G&@dJ &B  
QBGjH^kL  
Fq_>}k@fI  
public synchronized int write(byte[] b,int nStart,int nLen) ,LlYRj 5  
{ #oR`_Dm)P  
int n = -1; \
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try{ )2#&l  
oSavedFile.write(b,nStart,nLen); H%etYpD  
n = nLen;
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} N&eo;Ti  
catch(IOException e) 5423Ky<
 
{ hlZ{bO'f  
e.printStackTrace (); IC(:RtJ  
} H XF
Y  
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k14<E/  
return n; F" M  
} 4w#2m>.  
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} wGw~ F:z  
}+bo?~2E&  
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/* O9E:QN<U`*  
**SiteInfoBean.java LokH4A17U  
*/ J3~%9MCJ  
package NetFox; j7QK8O$XL  

4/k`gT4  
&3;"$P  
public class SiteInfoBean { D~BL Txq  
g4W/T  
H(tC4'tA  
private String sSiteURL; //Site's URL D[?;+g/  
private String sFilePath; //Saved File's Path !icI Rqcf=  
private String sFileName; //Saved File's Name idGn{f((f  
private int nSplitter; //Count of Splited Downloading File s^SU6P/]  
"(vK.-T  
^1vKhO+p$  
public SiteInfoBean() UP$>,05z6  
{//nSplitter的缺省值为5 L6DYunh}^N  
//default value of nSplitter is 5 k52IvB@2  
this("","","",5); MmfBFt*  
} +3o0GJ  
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?|/K(}  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) *9uNM@7&0  
{ ^_g%c&H  
sSiteURL= sURL; !LM`2|3$  
sFilePath = sPath; M. % p'^5  
sFileName = sName;
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this.nSplitter = nSpiltter;
@/|g|4  
<
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} 8)=(
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</D.}ia  
}Hq3]L
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public String getSSiteURL() Ez"*',(  
{ ZI;*X~h  
return sSiteURL; (,jsZ!sl  
} n6.Z{Q'b  
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{9-9!jN{"  
public void setSSiteURL(String value) o $W@@aM  
{ cTzR<Yr  
sSiteURL = value; ?upd  
} t-o,iaPG3  
t&EizH$  
4H%#Sn#L^!  
public String getSFilePath() |aAyWK S  
{ &M<"Fmn  
return sFilePath; TWGn:mi  
} j6RV{Lkr_  
c0o Z7)*}  
az:}RE3o  
public void setSFilePath(String value) >l><d!
hw  
{ yo->mD  
sFilePath = value; *$|f9jVh  
} ^|p D(v  
LH)1IGAx2y  
i
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public String getSFileName() axph]o@ y@  
{ s>I]_W)Pt  
return sFileName; sR>>l3H
 
} fS/:OnH  
M>Tg$^lm  
}2LWDQ;po  
public void setSFileName(String value) u"(NN9s  
{ Y'~O_coG  
sFileName = value; !j`<iPI7B  
} UkpTK8>&  
*]NfT}}  
/;+\6(+X  
public int getNSplitter() fdX|t"oz  
{ ][tR=Y#&y5  
return nSplitter; hU-FSdR  
} `|>]P"9yp  
Hzm_o>
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7yT/t1)  
public void setNSplitter(int nCount) l
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{ "qF/7`e[  
nSplitter = nCount; \%Y`>x.  
} NQ;X|$!zH  
} 97\K]Tr  
p7-\a1P3  
L&)e}"  
/* aVK,(j9u  
**Utility.java mj e9i  
*/ s|A[HQUtJ  
package NetFox; e+-#/i*  
6q8}8;STTY  
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public class Utility { DJ<+" .v!  
.O'~s/h  
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public Utility() Nv.  
{ (wq8[1Wzup  
#<"od'{U  
g[1>|Ax`'  
} ]?H12xz  
-K?lhu  
//线程睡眠 ^*`#+*C  
public static void sleep(int nSecond) Jh=.}FXnjL  
{ l$\B>u,>  
try{ N,rd=
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Thread.sleep(nSecond); J-'XT_k:iM  
} ,
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catch(Exception e) &.DRAD)  
{ B
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e.printStackTrace (); {g1"{
 
} VFZ?<m  
} ,M?8s2?  
u8KQV7E  
//日志 Dt[+HCCY:  
public static void log(String sMsg) LH_H yP_  
{ |[iO./zP  
System.err.println(sMsg); 3%(r,AD  
} Be@g|'r  
;z9,c  
I50LysM  
public static void log(int sMsg) 1c#\CO1l  
{ \9OKf|#j  
System.err.println(sMsg); \RR` F .7  
} A32Sdr'D  
} ?2da6v,t  
f!yl&ulKU  
5j.@)XXe  
/* WHBGhU  
**TestMethod.java "Hz%0zP&  
*/ $`W3`}#fM  
package NetFox; O&aD]~|
  
 rn( drG  
4[x`\  
public class TestMethod { 2;"vF9WMm  
8%u|[Si;  

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public TestMethod() ysK J=  
{ ///xx/weblogic60b2_win.exe DFQ`(1Q  
try{ <";1[A%7<  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); H $Az,-P  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); oY0b8=[  
SiteFileFetch fileFetch = new SiteFileFetch(bean); _F[a2PE2+  
fileFetch.start(); 1G12FV>M  
} @fmp2!?6  
catch(Exception e){e.printStackTrace ();} i0wBZ i?  
@d~]3T  
:Ob^b3<t  
} =>c0NT  
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public static void main(String[] args) 5EQ)pH+  
{ aWRi`poZT
 
new TestMethod(); @0PWbs$  
} ?'a>?al%>  
} u(8{5"
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