http断点续传简单实现（java)

/* ;vgaFc]  
**SiteFileFetch.java wUmcA~3D  
*/ mB*;>   
package NetFox; d?=r:TBU  
import java.io.*; D(M^%z2N  
import java.net.*; QeD ;GzG  
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public class SiteFileFetch extends Thread { Oa7jLz'i  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 6/L34VH  
long[] nStartPos; //开始位置 ,}$[;$ye  
long[] nEndPos; //结束位置 wmFS+F4`2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 FJ O-p  
long nFileLength; //文件长度 2Xp?O+b#"O  
boolean bFirst = true; //是否第一次取文件 4NmLbM&C8  
boolean bStop = false; //停止标志 P64<O5l/  
File tmpFile; //文件下载的临时信息 ((]Sy,rdk  
DataOutputStream output; //输出到文件的输出流 &+8cI^kp  
'V:ah38  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） /??nOVvt  
public SiteFileFetch(SiteInfoBean bean) throws IOException +rOd0?  
{ 6ieP` bct  
siteInfoBean = bean; 'E#Bz"
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); x5W. 3*  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); !a9/8U_>XF  
if(tmpFile.exists ()) >66v+  
{ @Yh%.#\i%  
bFirst = false; &, WQ
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read_nPos(); }%k3  
} ~.8p8\H  
else Y kc
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{ O.OSLezTQ  
nStartPos = new long[bean.getNSplitter()]; &e1(|qax  
nEndPos = new long[bean.getNSplitter()]; R}\n@X*  
} z4*`K4W  
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} VAZ6;3@cd  
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public void run() %n>*jFC  
{ wm_o(Z}  
//获得文件长度 dzyp:\&9  
//分割文件 WhN~R[LE_  
//实例FileSplitterFetch @wOX</_g  
//启动FileSplitterFetch线程 CqbPUcK  
//等待子线程返回 OqA#4h4^  
try{ OG}m+K&<  
if(bFirst) p*"H&xA@  
{ E=8$*YUW(g  
nFileLength = getFileSize(); [78^:q-/0  
if(nFileLength == -1) uOprA`3  
{ 63y&MaqSJ  
System.err.println("File Length is not known!"); ma(E}s  
} GJ4R f%  
else if(nFileLength == -2) OO`-{HKt  
{ haIH `SY  
System.err.println("File is not access!"); 1A-ess\  
} R3gg{hQ  
else \v[?4[  
{ YV
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for(int i=0;i<nStartPos.length;i++) ld/\`s[i  
{ UqaV9  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 8!u8ZvbFG  
} mA>u6Rlc  
for(int i=0;i<nEndPos.length-1;i++) T_b$8GYfCY  
{ Dg2=;)"L  
nEndPos = nStartPos[i+1]; khtYn.eaL  
} \t\ZyPxn  
nEndPos[nEndPos.length-1] = nFileLength; uGH>|V9'c  
} fI1,L"  
} !_My
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8\@&~&(y:
 
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//启动子线程 %(y0,?*  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length];
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for(int i=0;i<nStartPos.length;i++) ;33LuD<h.  
{ Q,z^eMk'd:  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), c@~j}(A  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), E8s&.:;+  
nStartPos,nEndPos,i); U<H< !NV  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); yCT:U&8%F  
fileSplitterFetch.start(); 6`Af2Y_  
} [<p7'n3x  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), DKxzk~sOM  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); XKt">W  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", tW|K\NL  
nEndPos = " + nFileLength); sX$EdIq  
// fileSplitterFetch[nPos.length-1].start(); _MC\\u/C/  
(r+#}z}  
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//等待子线程结束 (R)(%I1Oz  
//int count = 0; O4i5fVy{  
//是否结束while循环 }+Ne)B E  
boolean breakWhile = false; jLu`DKB  
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W4~:3Sk  
while(!bStop) Ot#O];3  
{ iI(7{$y  
write_nPos(); 1"5-doo  
Utility.sleep(500); R"`7aa6  
breakWhile = true; ypK1 sw  
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for(int i=0;i<nStartPos.length;i++) "=97:H{!  
{ OPsg3pW!]  
if(!fileSplitterFetch.bDownOver) =Vm"2g,aA  
{ T2^0Q9E?  
breakWhile = false; ) ]x/3J@  
break; N1O.U"L;  
} xVn"xk  
} qvH7
otA  
if(breakWhile) U*sQYt<?g  
break; 9OnH3  
ZfYva(zP{Q  
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//count++; SuU_psF  
//if(count>4) `pzXh0}|  
// siteStop(); rL
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} 8I`t`C/4  
|3A/Og  
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System.err.println("文件下载结束！"); xF4>D!T%8  
} tgPx!5U  
catch(Exception e){e.printStackTrace ();} Y]SX2kk(2  
} 8(EK17rE`  
2HemPth  
8- U1Y  
//获得文件长度 X<<hb  
public long getFileSize() D< h+r?  
{ hS}d vZa  
int nFileLength = -1; feH|sz`e  
try{ }Ra'`;D$  
URL url = new URL(siteInfoBean.getSSiteURL()); }yfSF|\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); !F_BLHig  
httpConnection.setRequestProperty("User-Agent","NetFox"); 9$u'2TV  
?!:$Z4G  
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int responseCode=httpConnection.getResponseCode(); Gw/imXL  
if(responseCode>=400) !6UtwCVR  
{ 5g{F-  
processErrorCode(responseCode); :bhpYEUMx  
return -2; //-2 represent access is error ^K#PcPF-j  
} t'@qb~sf  
!u0qF!/W  
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String sHeader; $]Vvu{  
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for(int i=1;;i++) _rz*7-ks=  
{ ]}~[2k.  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); El}."}l&  
//Utility.log(in.readLine()); =D2jJk?AX  
sHeader=httpConnection.getHeaderFieldKey(i); .9< i  
if(sHeader!=null) 9,4Lb]  
{ LXIQpD,M  
if(sHeader.equals("Content-Length")) cnUYhxE+s  
{ %$)[qa3  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); FM)Es&p&  
break; YB^[HE\#y  
} #Tjv(O[&  
} %)Pn<! L  
else [=63xPxs.  
break; {q[l4_  
} `Eijy3>h  
} Ez*9*]O*+  
catch(IOException e){e.printStackTrace ();} /WlpRf%  
catch(Exception e){e.printStackTrace ();} yH'vhtop  
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Utility.log(nFileLength); l.#iMi(@p~  
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return nFileLength; yj6o533o  
} 4+Sq[Rv0  
+$hqwNh@Z@  
y7;i4::A\  
//保存下载信息（文件指针位置） ;<JyA3i^V,  
private void write_nPos() nty^De%  
{ meHnT9a^  
try{ cBl F  
output = new DataOutputStream(new FileOutputStream(tmpFile)); oQ!56\R  
output.writeInt(nStartPos.length); D{]t50a.  
for(int i=0;i<nStartPos.length;i++) &vf%E@<  
{ GvL)SVv?  
// output.writeLong(nPos); E,F'k2yU  
output.writeLong(fileSplitterFetch.nStartPos); 1 h.=c  
output.writeLong(fileSplitterFetch.nEndPos); \a|FhhI  
} P,2FH2Eyj  
output.close(); RJo"yB$1e6  
} ~VRt6C  
catch(IOException e){e.printStackTrace ();} j{i3lGaN  
catch(Exception e){e.printStackTrace ();} .o(XnY)cgJ  
} C6=P(%y  
_
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//读取保存的下载信息（文件指针位置） H8V${&!ho  
private void read_nPos() _%M5 T  
{ 7fVlA"x  
try{ hP=^JH  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 6^vMJ82U  
int nCount = input.readInt(); JF%eC}[d  
nStartPos = new long[nCount]; I.[2-~yf  
nEndPos = new long[nCount]; D;pfogK @  
for(int i=0;i<nStartPos.length;i++) DS@ZE Q`F  
{ lG\6z"K  
nStartPos = input.readLong();
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nEndPos = input.readLong(); )%4%Uo_Xm  
} 6*] g)m  
input.close(); -R^OYgF  
} u~|D;e  
catch(IOException e){e.printStackTrace ();} x<m{B@3T  
catch(Exception e){e.printStackTrace ();} x
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} ZfPWH'P  
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private void processErrorCode(int nErrorCode) i?.7o*w8  
{ i`]-rM%J#  
System.err.println("Error Code : " + nErrorCode); _vQtV]  
} %SG**7  
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//停止文件下载 F~;G[6}  
public void siteStop() 39xAh*}G]  
{ )ZU)$dJ>V  
bStop = true; K3uNR w  
for(int i=0;i<nStartPos.length;i++) ~i)m(65:  
fileSplitterFetch.splitterStop(); {*gO1TZt9  
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} I<
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} [Yo3=(7J  
//负责部分文件的抓取 j.? '*?P  
**FileSplitterFetch.java AY{-Hf&  
*/ *SW.K{{  
package NetFox; E8[{U8)[;5  
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import java.io.*; q .[hwm  
import java.net.*; %^e
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public class FileSplitterFetch extends Thread { [D8u.8q  
y\=(;]S'  
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String sURL; //File URL D(EY"s37  
long nStartPos; //File Snippet Start Position sFd"VRAV~E  
long nEndPos; //File Snippet End Position !H,_*u.  
int nThreadID; //Thread's ID vdwh59W  
boolean bDownOver = false; //Downing is over 5_bIc=L1  
boolean bStop = false; //Stop identical svt%UE|_:$  
FileAccessI fileAccessI = null; //File Access interface 2E V M*^A  
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;.Lf9XJ   
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException p$>e{
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{ _/@VV5Mq  
this.sURL = sURL; G+k[.  
this.nStartPos = nStart; mN5`Fct*A>  
this.nEndPos = nEnd; pF)}<<C  
nThreadID = id; e(;1XqLM  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 z:RclDm  
} t<_Jx<{2  
:lF[k`S T  
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public void run() _cz&f%qr  
{ f.V
1  
while(nStartPos < nEndPos && !bStop) wYZ"fusT  
{ N|Cx";,|FZ  
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try{ 64qm  
URL url = new URL(sURL); W/z\j/Rgc  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); oV4+w_rrLc  
httpConnection.setRequestProperty("User-Agent","NetFox"); S >E|A%  
String sProperty = "bytes="+nStartPos+"-"; 1b4aY> Z  
httpConnection.setRequestProperty("RANGE",sProperty); "`b"PQ<x  
Utility.log(sProperty); n5nV461U  
@,Je*5$o"  
Irk@#,{<  
InputStream input = httpConnection.getInputStream(); HPc7Vo(  
//logResponseHead(httpConnection); 4nC`DJ;V  
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byte[] b = new byte[1024]; a&>Tk%  
int nRead; q3+G  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 2k\i/i/Y  
{ :K%{?y  
nStartPos += fileAccessI.write(b,0,nRead); 9fk@C/$  
//if(nThreadID == 1) #[.vfG  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'qGKS:8  
} w]Q0}Z  
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Utility.log("Thread " + nThreadID + " is over!"); x/nlIoT  
bDownOver = true; ]ne&`uO  
//nPos = fileAccessI.write (b,0,nRead); adHZX  
} <+MNv#1:w  
catch(Exception e){e.printStackTrace ();} {@T8i^EI  
} GCN(  
} Qt+|s&HGt  
./_o+~\e'  
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//打印回应的头信息 @agW{%R:.  
public void logResponseHead(HttpURLConnection con) uZsm=('ww  
{ UlBg6  
for(int i=1;;i++) 8&15kA  
{ . &dh7`l  
String header=con.getHeaderFieldKey(i); 2o0.ttBAqZ  
if(header!=null) 0\G`AO;D  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); V=<OV]0  
Utility.log(header+" : "+con.getHeaderField(header)); Pn)^mt  
else ^;J@]&[ ~  
break; l0cws`V  
} zCrDbGvqF`  
} @@L@r6  
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public void splitterStop() (!h%) _?.l  
{ sOc<'):TK  
bStop = true; 7U#`^Q}  
} f_`gUMf  
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} 7%p[n;-o&  
i ! wzID  
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/* tw.2h'D  
**FileAccess.java >QwZt  
*//文件访问(定位，写) pfj%AP:  
package NetFox; d*%-r2K  
import java.io.*; yZf+*j/a7  
(<ybst6+I  
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public class FileAccessI implements Serializable{ S~WsGLF s  
[m*=Q  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 n\v\<mVTb7  
RandomAccessFile oSavedFile; :Jp$_T&E  
long nPos; z7+y{-{Z  
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public FileAccessI() throws IOException 0 S3~IeJ  
{ Ndj9B|s_  
this("",0);
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} ;6N@raP7  
lk $S"OH!  
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public FileAccessI(String sName,long nPos) throws IOException )A]
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{ Fs q=u-= :  
oSavedFile = new RandomAccessFile(sName,"rw"); QJFx/zU  
this.nPos = nPos; {7^7)^@  
oSavedFile.seek(nPos); yteJHaq  
} rvT75dV0  
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.pNPC|XU  
public synchronized int write(byte[] b,int nStart,int nLen) `Q2 `":  
{ 6l|pTyb1  
int n = -1; Wc4K?3 ZM  
try{ $M\[^g(q  
oSavedFile.write(b,nStart,nLen); uMm/$#E  
n = nLen; -#]?3*NO  
} jEBZ"Jvb  
catch(IOException e) o[AQS`  
{ /p~Wk4'  
e.printStackTrace (); 8" Z!: =A  
} csTX',c  

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return n; {Y{*(5YV  
} k[oU}~*U+  
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} azMrY<  
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/* }a@ZFk_>  
**SiteInfoBean.java [V`j@dV  
*/ qX{m7  
package NetFox; ehE
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>j1\]uo  
public class SiteInfoBean { i][7S mN  
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private String sSiteURL; //Site's URL ;czMsHu0X  
private String sFilePath; //Saved File's Path iqCKVo7:M  
private String sFileName; //Saved File's Name w5"C<5^  
private int nSplitter; //Count of Splited Downloading File jqHg'Fq  

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public SiteInfoBean() 11}fPWK  
{//nSplitter的缺省值为5 ToIvyeFr  
//default value of nSplitter is 5 a pqzf  
this("","","",5); $3](6  
} }fw;{&s{z  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) WSfla~-'F  
{ ^=Rqa \
;  
sSiteURL= sURL; .)^@[yrkz  
sFilePath = sPath; 5J1A|qII  
sFileName = sName; b7>^w<ki  
this.nSplitter = nSpiltter; E)|_7x<u  
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} j(G}4dib  
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public String getSSiteURL() *W q{ :k  
{ K^AX=B  
return sSiteURL; XtfO;`  
} 9&5\L  
@YmD 79  
ann!"s_  
public void setSSiteURL(String value) 'Omi3LXfDT  
{ ^\ &:'$f+8  
sSiteURL = value; ]H7_bix  
} 8Dpf{9Y-E  
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public String getSFilePath() W5?F?Dp!v  
{ z<rdxn,9  
return sFilePath; pmXx2T#=  
} wzB*M}3  
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public void setSFilePath(String value) $DW3H1iW  
{ f
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sFilePath = value; QOIi/flK  
} 9@C3jZ+9`H  
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''!pvxA  
public String getSFileName() *!UY;InanX  
{ 5=Mm=HyI2  
return sFileName; |jm|/{lc  
} 3ydOBeY  
70&v
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public void setSFileName(String value) eN{[T PPCq  
{ yyh L]Uq"=  
sFileName = value; u814ZN}  
} %*P59%  
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public int getNSplitter() 1Nx.
aji  
{ qEKTSet?  
return nSplitter; HyXw^ +tsj  
} "!XeK|Wi  
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public void setNSplitter(int nCount) YE&"IH]lF  
{ La?q>  
nSplitter = nCount; c
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} 2
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} )F&@ M;2p'  
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/* 7P9n. [  
**Utility.java 1N
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*/ I"@X~Y7}  
package NetFox; y|q4d(P.  
d9|dHJf  
#/@U|g  
public class Utility { gBHev1^y  
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public Utility() Jl&bWp^3  
{ j11\t  
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( gO?-0  
} PC/fb-J  
#})Oz| c  
//线程睡眠 ]>/YU*\  
public static void sleep(int nSecond) !`\W8JT+  
{ Dqe)8 r  
try{ ?LgR8/Io@5  
Thread.sleep(nSecond); l9)iLOj  
}
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catch(Exception e) ~j3B'  
{ Yqm
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e.printStackTrace (); #NNj#  
} >joGGT  
}
5. :To2  
3/:O8H  
//日志 0~A<AF*t  
public static void log(String sMsg) UA{sUj+?  
{ # j*$ `W;  
System.err.println(sMsg); [V{JuG;s  
} KoiU\r  
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public static void log(int sMsg) /V~L:0%  
{ P~_CDh.N  
System.err.println(sMsg); 0{v?  
} {b^naE  
} [ar:zlV8  
4DEsB)%X  
cGkl=-oQ'  
/* R%aH{UhE`  
**TestMethod.java b@^M|h.Va  
*/ lZ0+:DaP2  
package NetFox; 52m^jT Sx  
?Li^XONz  
a%tm[Re  
public class TestMethod { `NXyzT`:K  
dpZ7eJ  
sxgR;gf6  
public TestMethod() _XXK1H x  
{ ///xx/weblogic60b2_win.exe 7EY~5U/4  
try{ YC&iH>jO3  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7;;W{W%  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ,M7sOp6}  
SiteFileFetch fileFetch = new SiteFileFetch(bean); f Otrn  
fileFetch.start(); |C'w] QYm  
} POH>!lHu  
catch(Exception e){e.printStackTrace ();} qS&PMQ"$  
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x~s>  
} H; TmG<S  
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public static void main(String[] args) MGc=TQ.  
{ @EfCNOy  
new TestMethod(); #H O\I7m  
} z(.$>O&6H  
} L)8+/+  
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