http断点续传简单实现（java)

/* w~?eX/;  
**SiteFileFetch.java t^;Fq{>  
*/ A8Y~^
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package NetFox; 7)wq9];w  
import java.io.*; Z}StA0F_  
import java.net.*; ]>T/Gl1  
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public class SiteFileFetch extends Thread { VO?NrKyeW  
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SiteInfoBean siteInfoBean = null; //文件信息Bean l6Bd<tSH  
long[] nStartPos; //开始位置 E zUjt)wF  
long[] nEndPos; //结束位置 UeQ%(f  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Sd11ZC6  
long nFileLength; //文件长度 GdY^}TJrh  
boolean bFirst = true; //是否第一次取文件 nK=V`  
boolean bStop = false; //停止标志 DL{a8t1L  
File tmpFile; //文件下载的临时信息 1_]l|`Po  
DataOutputStream output; //输出到文件的输出流 ?&_\$L[  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） biK.HL\V  
public SiteFileFetch(SiteInfoBean bean) throws IOException syvi/6  
{
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siteInfoBean = bean; Mpx.n]O.  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); /% 1lJD  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); r6G)R+#  
if(tmpFile.exists ()) T+hW9pa)  
{ xy>mM"DOH  
bFirst = false; Pw{+7b$  
read_nPos(); 0l*/_;wo  
} GjBQxn  
else ?OFvGd  
{ `BY`ltW  
nStartPos = new long[bean.getNSplitter()]; T94$}- 5/)  
nEndPos = new long[bean.getNSplitter()]; d0az#Yg!  
} \3/'#  
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} ]B||S7idq  
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public void run() +/
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{ Fy^\Uw  
//获得文件长度 nceF4Ty  
//分割文件 jL<.?HE  
//实例FileSplitterFetch ~5b %~:  
//启动FileSplitterFetch线程 q[lqEc  
//等待子线程返回 sYzG_*)  
try{ hV)I C9  
if(bFirst) rYJvI  
{ W%o){+,  
nFileLength = getFileSize(); Jo ^o`9  
if(nFileLength == -1) (ym)q#^  
{ 5I14"Qf  
System.err.println("File Length is not known!"); ;DTNw=  
} >J1o@0tk  
else if(nFileLength == -2) Z:Wix|,ONS  
{ E:ytdaiT  
System.err.println("File is not access!"); =@'"\ "Nh  
} #LZ`kSlv4  
else @N$r'@  
{ T7v8}_"-  
for(int i=0;i<nStartPos.length;i++) S.z;Bm  
{ >cp9{+#f  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); y-U(`{[nM  
} U7W ct %  
for(int i=0;i<nEndPos.length-1;i++) W[jxfZD9v  
{ LLE~V~j  
nEndPos = nStartPos[i+1]; xl3U  
} qz:OnQv!  
nEndPos[nEndPos.length-1] = nFileLength; UpITx]y?"m  
} qhtc?A/0}  
} 1L0ku@%t9Y  
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//启动子线程 >@X=E3  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; OKP?^%kD  
for(int i=0;i<nStartPos.length;i++) bMZ0%(q
 
{ /X?Nv^Hy  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), [Xrq+O,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 1ysA~2  
nStartPos,nEndPos,i); ;?rW`e2  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _I9TG.AA.  
fileSplitterFetch.start(); }8svd#S+  
} kB 2bT}  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), l*eA ?Qz  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); yDKX,  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", C"sa.#}  
nEndPos = " + nFileLength); Vf@/}=X *  
// fileSplitterFetch[nPos.length-1].start(); Ub"\LUu  
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//等待子线程结束 [kXe)dMX8  
//int count = 0; wK3}K  
//是否结束while循环 B5cTzY.h-  
boolean breakWhile = false; oH;Y}h  
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while(!bStop) ("aYjKk  
{ k91Y"_&  
write_nPos(); qUo(hbp  
Utility.sleep(500); 5mV'k"Om#"  
breakWhile = true; "[%NXan  
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 LKm5U6  
for(int i=0;i<nStartPos.length;i++) e0qa~5  
{ X[|>r@Aa!  
if(!fileSplitterFetch.bDownOver) D&'".N,}  
{ 7}*5Mir p  
breakWhile = false; 0QPipuP  
break; 3drgB;:g`  
} /i]Gg \)  
} QW!'A`*x  
if(breakWhile) WgIVhj  
break; Q=dR[t>^  
kN_LD
-  
2|T@  
//count++; u/MIB`@,  
//if(count>4) _E~uuFMn*R  
// siteStop(); !=-l760  
} 7fVVU+y  
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System.err.println("文件下载结束！"); o;O_N^_W  
} uIR_p\)  
catch(Exception e){e.printStackTrace ();} FPqgncBHK  
} )j$Bo{  
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=#W{&Te;  
//获得文件长度 3B_S>0H"$  
public long getFileSize() )JjfPb64  
{ ZF`ckWT:-N  
int nFileLength = -1; isaT0__8  
try{ AXJC&O}`  
URL url = new URL(siteInfoBean.getSSiteURL()); U9@q"v-  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
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httpConnection.setRequestProperty("User-Agent","NetFox"); IXH;QwR:  
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int responseCode=httpConnection.getResponseCode(); 6L4B$'&KQZ  
if(responseCode>=400) & z?y  
{ 3U}z?gP[  
processErrorCode(responseCode); Lrk^<:8;  
return -2; //-2 represent access is error T"2ye9a  
} 1mB6rp  
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String sHeader; k<St:X%.O  
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for(int i=1;;i++) ]2( %^#qBG  
{ \zKVgywR  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); H kg0;)  
//Utility.log(in.readLine()); ;A|6&~E0G  
sHeader=httpConnection.getHeaderFieldKey(i); KLoHjBq  
if(sHeader!=null) 7`P(LQAr!  
{ o`&idn|,  
if(sHeader.equals("Content-Length")) 3GaM>w}>W  
{ 6#.R'O  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); t4,6`d?C  
break; z`/v}'d[X  
} XX/cJp  
} 6-<r@{m$  
else `B^?Za,xN  
break; 1W;+hXx  
} ost~<4~  
} ($ae n  
catch(IOException e){e.printStackTrace ();} Qs~;?BH&  
catch(Exception e){e.printStackTrace ();} ~DC
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Utility.log(nFileLength); R(Z2DEt</  
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return nFileLength; sYeZ.MacU  
} b`1P%OjC  
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//保存下载信息（文件指针位置） 4,uH 4[7  
private void write_nPos() 2<<,a
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{ ]2tX'=X  
try{ ?-*_v//g  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 1!,lI?j,  
output.writeInt(nStartPos.length); YMJ?t"  
for(int i=0;i<nStartPos.length;i++) ='YR;  
{ 5.idC-\  
// output.writeLong(nPos); ZSHc@r*>  
output.writeLong(fileSplitterFetch.nStartPos); U JY`P4(  
output.writeLong(fileSplitterFetch.nEndPos); *p+%&z_<  
} IaN|
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output.close(); YW}1Mf=_  
} hO\_RhsRy?  
catch(IOException e){e.printStackTrace ();} O+c@B}[!  
catch(Exception e){e.printStackTrace ();} k4s >sd3 5  
} x1wm]|BIf  
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//读取保存的下载信息（文件指针位置） ]w! x  
private void read_nPos() X8F _Mb*  
{ |Q.t]TR'P  
try{ @yqy$I
  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); .#Z}}W#  
int nCount = input.readInt(); EcFYP"{
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nStartPos = new long[nCount]; y~''r%]  
nEndPos = new long[nCount]; <#LH
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for(int i=0;i<nStartPos.length;i++) iiKFV>;t/  
{ JYs*1
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nStartPos = input.readLong(); ]#TL~u[  
nEndPos = input.readLong(); YtE V8w_$  
} U
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input.close(); I3p ~pt2  
}  E~jNUTq  
catch(IOException e){e.printStackTrace ();} zZGPA j  
catch(Exception e){e.printStackTrace ();} GAEz :n  
} H>a3\M  
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private void processErrorCode(int nErrorCode) ey@y?X=  
{ XBdC/DM[  
System.err.println("Error Code : " + nErrorCode);  \^w=T*  
} ) ^!oM  
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e*:[#LJ]C  
//停止文件下载 :$j!e#?=  
public void siteStop() L*11hy
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{ .9S  
bStop = true; v5RS<?o  
for(int i=0;i<nStartPos.length;i++)
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fileSplitterFetch.splitterStop(); R1\cAP^0  
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} LPvyfD;Zy  
} G]=U=9ZI  
//负责部分文件的抓取 = r_&R#~GT  
**FileSplitterFetch.java #$e~o}(r  
*/ 0[x?Q[~S_0  
package NetFox; Zj
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import java.io.*; EAqTXB@XU  
import java.net.*; mv)M9c,`  
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public class FileSplitterFetch extends Thread { 72@8M  
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String sURL; //File URL \"<&8  
long nStartPos; //File Snippet Start Position bv)E>%Yy  
long nEndPos; //File Snippet End Position cs8bRXjHa  
int nThreadID; //Thread's ID 7=6p  
boolean bDownOver = false; //Downing is over axxdW)+K  
boolean bStop = false; //Stop identical 7"Zr:|$U  
FileAccessI fileAccessI = null; //File Access interface 0/#XUX 4  
= K"F!}  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException !3-mPG< ]  
{ J3}^\k=p"  
this.sURL = sURL; e-]k{_wm  
this.nStartPos = nStart; r%&hiobMYs  
this.nEndPos = nEnd; K
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nThreadID = id; aGr(djD  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 3|[:8  
} ;^=eiurv  
.]k(7F!W  
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public void run() `i9WnPRt  
{ 5lxC**NA  
while(nStartPos < nEndPos && !bStop) Z@RAdwjR`p  
{ /d0LD  
\
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%&V<kH"7Q{  
try{ |*Z'WUv  
URL url = new URL(sURL); WvAl!^{`  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Y\%R6/Gj|u  
httpConnection.setRequestProperty("User-Agent","NetFox"); %_@8f|# ,M  
String sProperty = "bytes="+nStartPos+"-"; 1;?b-FEq:  
httpConnection.setRequestProperty("RANGE",sProperty); }u5 Mexs  
Utility.log(sProperty); Zdr +{-  
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InputStream input = httpConnection.getInputStream(); z }R-J/xr2  
//logResponseHead(httpConnection); <$Q&n{  
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byte[] b = new byte[1024]; oMkB!s  
int nRead; deda=%w
0  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ''?.6r  
{ shYcfLJ  
nStartPos += fileAccessI.write(b,0,nRead); v
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//if(nThreadID == 1) mu=u!by.E  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); P`-(08t  
} !r.X.C  
$O%lYQY]  
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Utility.log("Thread " + nThreadID + " is over!"); e&<#8;2X  
bDownOver = true; ]^8:"Ky'  
//nPos = fileAccessI.write (b,0,nRead); E@0wt^  
} nDMNaMYb  
catch(Exception e){e.printStackTrace ();} ["Z]K'?P  
} D<5gdIw  
} i._d^lR\t  
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//打印回应的头信息 N9
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public void logResponseHead(HttpURLConnection con) [|ky~sRr  
{ G?<L{J2"Q  
for(int i=1;;i++) }1:jM_H)k  
{ Dr7,>Yx  
String header=con.getHeaderFieldKey(i); #y-OkGS ^  
if(header!=null) O4]Ss}ol  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 0b?9LFd  
Utility.log(header+" : "+con.getHeaderField(header)); y?_tSnDK  
else vkc(-n  
break; i:qc2#O:J  
} }\JoE4  
} 8%arA"#S  
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public void splitterStop() R?Iv<(I  
{ rH8?GR0<  
bStop = true; |I)MsNF  
} 3j]La  

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} q^"P_pV\  
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7QQ3IepP  
/* {;f`t3D  
**FileAccess.java lJ}G"RT
m  
*//文件访问(定位，写) G1$DVGo  
package NetFox; &|/C*2A  
import java.io.*; d<`Z{"g NS  
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public class FileAccessI implements Serializable{ mEyZ<U9  
< g6 [mS  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 $sGX%u  
RandomAccessFile oSavedFile; F'pD_d9]e  
long nPos; 8Vl!&j0s^  
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public FileAccessI() throws IOException 4A|5eg9N  
{ j%[|XfM  
this("",0); AD*+?%hj  
} xQWZk`6~L  
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public FileAccessI(String sName,long nPos) throws IOException 42Kzdo|}  
{ L|!9%X0.  
oSavedFile = new RandomAccessFile(sName,"rw"); R^%7|  
this.nPos = nPos; (Q#A Br8  
oSavedFile.seek(nPos); t)$>++i  
} h7gH4L!'u  
-2% []  
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public synchronized int write(byte[] b,int nStart,int nLen) zzq/%jki  
{ g>VkQos5"  
int n = -1; R:^GNra;  
try{ /oe="/y6  
oSavedFile.write(b,nStart,nLen); ZVK;m1?'  
n = nLen; {U-VInu  
} "}Ya.  
catch(IOException e) BR"*-$u0;  
{ 
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e.printStackTrace (); lFI"U^xC  
} iwrdZLE  
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return n; ^[^uDE <  
} < 8WS YZ  
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} )1H]a'j  
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/* 1Voo($q.  
**SiteInfoBean.java fv<
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*/ nCXIWLw  
package NetFox; f[h=>O  
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public class SiteInfoBean { :q^g+Bu=  
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private String sSiteURL; //Site's URL 4/Ok/I  
private String sFilePath; //Saved File's Path ad i5h  
private String sFileName; //Saved File's Name cs~ }k7><  
private int nSplitter; //Count of Splited Downloading File &$vDC M4  
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public SiteInfoBean() N#]f?6*R  
{//nSplitter的缺省值为5 m!E36ce}  
//default value of nSplitter is 5 FW[<;$  
this("","","",5); .eq-i>  
} ~''qd\.f$  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 8>Ervi`  
{ &<.Z4GxS  
sSiteURL= sURL; q:1 1XPP  
sFilePath = sPath; 5\EHu8  
sFileName = sName; ?ix0n,m  
this.nSplitter = nSpiltter; q w|M~vdm  
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=eTI@pN`  
} i!YZF$|  
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public String getSSiteURL() ~~ )&? \N  
{ k 2;m"F  
return sSiteURL; wyAqrf  
} CcAsJX~_  
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public void setSSiteURL(String value) W+Gu\=s%O  
{ ,FS iE\  
sSiteURL = value; '>'h
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} d'Gv\i&e  
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public String getSFilePath() =p&6A^  
{ Q 7B)t;^  
return sFilePath; \mWXr*;  
} !d
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public void setSFilePath(String value)  s.GTY@t  
{ y~ ^>my7G  
sFilePath = value; a
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} -uO< ]  
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public String getSFileName() uz'beE  
{ vbwEX6  
return sFileName; *xL#1  
} *p.ELI1IC  
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public void setSFileName(String value) &[RC4^;\V  
{ <J
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sFileName = value; nV']^3b  
} Mh3zl  
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public int getNSplitter() 2px5>4<  
{ X8;03EW;  
return nSplitter; |G%MiYd  
} P?]q*KViM  
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public void setNSplitter(int nCount) lD C74g  
{ %@pTEhpF  
nSplitter = nCount; O5k's  
} *j<;;z-  
} A9tQb:  
7Jc=`Zm'  
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/* WQ"ZQ  
**Utility.java 2M1yw "  
*/ @ju-cv+  
package NetFox; :B=`^>RK  
]/d2*#  
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public class Utility { VK`b'U&l"  
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aty K^*aX  
public Utility() s|{K?s  
{ #UXmTrZ.  
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} Bpk%,*$*)  
*xLMs(gg  
//线程睡眠 1bj75/i<6  
public static void sleep(int nSecond) W%1fm/G0  
{ w;#9 hW&  
try{ )k7`!@ID  
Thread.sleep(nSecond); KCCS7l/  
} 03rZz1  
catch(Exception e) 9sT?"(=  
{ (Yw5X_|  
e.printStackTrace (); '`3-X];p  
} $B$=,^)3  
} 1/#N{rZ  
8n&",)U  
//日志 c\;}ov+  
public static void log(String sMsg) 93'%aSDI%  
{ ,;D74h2F  
System.err.println(sMsg); 1W/= =+%I  
} Xr
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p.l]%\QI  
".w*_1G7U  
public static void log(int sMsg) |]m&LC  
{ nh E!Pk  
System.err.println(sMsg); *dKA/.g  
} Bj
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} -k<.Q=]<t  
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Z;n}*^U  
/* g#70Sg*d  
**TestMethod.java Pq_Il9  
*/ g~V{Ca;}  
package NetFox; D#k>.)g  
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public class TestMethod { |r /}r,t}  
L g%cVSz/C  
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public TestMethod() n1cAI|ZE  
{ ///xx/weblogic60b2_win.exe o#+!H!C.O  
try{ >w*"LZjTTK  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); I
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//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); IH:Hfv  
SiteFileFetch fileFetch = new SiteFileFetch(bean); zJx<]=]  
fileFetch.start(); :V_$?
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} IXg${I}_Q  
catch(Exception e){e.printStackTrace ();} +"p",Z  
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} |H@M-  
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\?
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public static void main(String[] args) TvQAy/Y0  
{ Kt^PL&A2  
new TestMethod(); =a {Z7W  
} -|3U0:'m  
} c`t1:%S  
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