http断点续传简单实现（java)

/* OwPH
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**SiteFileFetch.java D5({&.X[-  
*/ 8z7eL>)  
package NetFox; PhV/WjCZ  
import java.io.*; X8}\m%gCU  
import java.net.*; Yl
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public class SiteFileFetch extends Thread { Z]WX 7d  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ut]UU*g^$  
long[] nStartPos; //开始位置 N!ay#V  
long[] nEndPos; //结束位置 ,UC|[-J  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 m\CU,9;;(  
long nFileLength; //文件长度 6R8>w,  
boolean bFirst = true; //是否第一次取文件 R]Z#VnL@qz  
boolean bStop = false; //停止标志 !>ZBb\EyK  
File tmpFile; //文件下载的临时信息 fx4#R(N  
DataOutputStream output; //输出到文件的输出流 s]`6uyW"  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） `F1Yfm jZT  
public SiteFileFetch(SiteInfoBean bean) throws IOException yS:w>xU @<  
{ |+JO]J#bc  
siteInfoBean = bean; )c1Pj#|  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); R/fE@d2~In  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); u rQvJ  
if(tmpFile.exists ()) ]Ol w6W?%  
{ 6(t'B!x  
bFirst = false; CS*lk!C  
read_nPos();
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} bG*l_  
else ^&y*=6C  
{ bivo7_  
nStartPos = new long[bean.getNSplitter()]; J}4RJ9  
nEndPos = new long[bean.getNSplitter()]; &'i>d&  
} p\#;(pf}s  
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} lx0BKD?n  
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public void run() -:Fr($^  
{ b"}ya/  
//获得文件长度 O'^AbO=,  
//分割文件 Oml3=TV  
//实例FileSplitterFetch [T)>RF  
//启动FileSplitterFetch线程 B-L@
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//等待子线程返回 Q>;Aq!mr=  
try{ oRcP4k;d=  
if(bFirst) %}-ogi
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{ wv\"(e7(  
nFileLength = getFileSize(); r4gLoHD)  
if(nFileLength == -1) y?3u6q++  
{ `('Up?  
System.err.println("File Length is not known!"); EG &me  
} W>?aZv  
else if(nFileLength == -2) g2}aEfp!H  
{
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System.err.println("File is not access!"); 4AvIU!0w  
} Z\QNn  
else 3m21n7F4*  
{ S
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for(int i=0;i<nStartPos.length;i++)  ;0$qT$,  
{ 9^C6ZgNS  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); f*hnzj  
} *!Gb_!98  
for(int i=0;i<nEndPos.length-1;i++) ;[g~h |{6  
{ Eg&Q,dH[  
nEndPos = nStartPos[i+1]; 4\ )WMP  
} 'u%_Ab_H  
nEndPos[nEndPos.length-1] = nFileLength; iWUxB28  
} 2\O!vp>|-  
} x 0vW9*&  
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//启动子线程 prIJjy-F  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 2JeEmG9  
for(int i=0;i<nStartPos.length;i++) [!} uj`e  
{ Kuk@x.~0m  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), yTe25l{QaF  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), LS#_K-  
nStartPos,nEndPos,i); #L*MMC"  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [5M!'  
fileSplitterFetch.start(); VzcW9'"#  
} +:
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), yd45y}uS;F  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); +, rm  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", v] Xy^7?  
nEndPos = " + nFileLength); n4"xVDL  
// fileSplitterFetch[nPos.length-1].start(); 3z#
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//等待子线程结束 I3l1 _  
//int count = 0; bOV]!)o  
//是否结束while循环 Nii5},  
boolean breakWhile = false; Ur""&@  
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while(!bStop) ?iaO6HD  
{ Na.e1A&?j  
write_nPos(); [f$pq5f='  
Utility.sleep(500); &mA{_|>  
breakWhile = true; z^%`sUgP  
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for(int i=0;i<nStartPos.length;i++) ::/vDUDc  
{ 
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if(!fileSplitterFetch.bDownOver) )hK;27m4  
{ MSt@yKq  
breakWhile = false; Z$)jPDSr  
break; %.{xo.`a[  
} |l?*' =  
} k9&pX8#  
if(breakWhile) PC!X<C8*  
break; U/rFH9e$  
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//count++; ]U 1S?p  
//if(count>4) h#|Ac>fz  
// siteStop(); sNC~S%[  
} gkx<<)y l  
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System.err.println("文件下载结束！"); %9t=Iu*  
} .8CfCRq  
catch(Exception e){e.printStackTrace ();} q&wv{  
} EixAmG  
f{D~ZC.*  
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//获得文件长度 GIUyW  
public long getFileSize() !t&C,@Ox  
{ Lez]{%+.`[  
int nFileLength = -1; )VxC v
  
try{ l-[5Zl;"  
URL url = new URL(siteInfoBean.getSSiteURL()); r
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); NX<Q}3cC  
httpConnection.setRequestProperty("User-Agent","NetFox"); S'AS,'EnY  
6uWPIM;  
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int responseCode=httpConnection.getResponseCode(); 28xLaob  
if(responseCode>=400) ~NO'8Mr  
{ 3:!5 ]  
processErrorCode(responseCode); BOW`{=  
return -2; //-2 represent access is error z8w@pT  
} 7!8R)m^1[  
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String sHeader; =$vy_UN  

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for(int i=1;;i++) 1f5;^T I  
{ th|TwD&mO  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 4=hz4(5a  
//Utility.log(in.readLine()); YR68'Sft[  
sHeader=httpConnection.getHeaderFieldKey(i); GG`;c?d@  
if(sHeader!=null) 6C*4' P9>  
{ jR,3-JQ  
if(sHeader.equals("Content-Length")) Jb`yK@x  
{ k.#[h@Pm  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); p/&s-GF  
break; 5%XEybc2  
} .^?Z3iA",  
} 1`Ek
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else fmk
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break; @)Sd3xw[  
} * n>YS  
} BQ77n2(@  
catch(IOException e){e.printStackTrace ();} tumYZ)nW  
catch(Exception e){e.printStackTrace ();} P;lDri  
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u=!n9
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Utility.log(nFileLength); <o&\/uO~H  
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return nFileLength; (C8r^m|A  
} $T}Dn[.  
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//保存下载信息（文件指针位置） *[wj )  
private void write_nPos() ~px)Jd  
{ WzO[-csy  
try{ n%:&N  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ;"DI)hdz  
output.writeInt(nStartPos.length); &<S]=\  
for(int i=0;i<nStartPos.length;i++) "Bbd[ZI8  
{ {}v<2bS  
// output.writeLong(nPos); RB/;qdqR  
output.writeLong(fileSplitterFetch.nStartPos); 2o9IP>#u  
output.writeLong(fileSplitterFetch.nEndPos); D,;6$Pvg^  
} FPXB>D'  
output.close(); 23[XmBf  
} 1c03<(FCd  
catch(IOException e){e.printStackTrace ();} 7e`h,e=  
catch(Exception e){e.printStackTrace ();} Lk]/{t0  
} 0@PI=JZ%  
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//读取保存的下载信息（文件指针位置） )qV&sru.$  
private void read_nPos() LDv>hzo  
{ )1S"D~j-  
try{ `?xE-S ;Pn  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 5Gsjt+ o  
int nCount = input.readInt(); 8n)3'ok  
nStartPos = new long[nCount]; Nc[V kJ]  
nEndPos = new long[nCount]; ,O]AB  
for(int i=0;i<nStartPos.length;i++) 2*@.hBi  
{ 5!^DKyw:  
nStartPos = input.readLong(); RI64QD  
nEndPos = input.readLong(); 1q;r4$n  
} 05Go*QvV  
input.close(); rA#Ji~  
} Cu+u'&U!  
catch(IOException e){e.printStackTrace ();} M-+=t8  
catch(Exception e){e.printStackTrace ();} piKR*|F  
} DANndXQLH  
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private void processErrorCode(int nErrorCode) 23=SXA!  
{ ,}_uk]AQ  
System.err.println("Error Code : " + nErrorCode); n"c3C)  
} &26H  
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//停止文件下载 JPfE`NZ  
public void siteStop() TZ+2S
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{ `h|>;u   
bStop = true; 1$
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for(int i=0;i<nStartPos.length;i++) X-=J7G`\h#  
fileSplitterFetch.splitterStop(); 1(12`3  
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} d9sqO9Ud8  
} t.E
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//负责部分文件的抓取 bZsg7[: C  
**FileSplitterFetch.java z@n779i  
*/ f.SmCgG  
package NetFox; =3?"s(9  
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import java.io.*; {Lm%zdk*k  
import java.net.*; ;NzS;C'  
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public class FileSplitterFetch extends Thread { o{&UT VyGs  
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String sURL; //File URL iNAaTU  
long nStartPos; //File Snippet Start Position HfgK0wIi  
long nEndPos; //File Snippet End Position =q
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int nThreadID; //Thread's ID Rr>h8Ni <  
boolean bDownOver = false; //Downing is over hPHrq{YZ  
boolean bStop = false; //Stop identical @|GKNW#  
FileAccessI fileAccessI = null; //File Access interface d~b#dcv$"  
{<3>^ o|"  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException SMdkD]{g  
{ {Qla4U  
this.sURL = sURL; T>;Kq;(9  
this.nStartPos = nStart;
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this.nEndPos = nEnd; d4#Ra%  
nThreadID = id; 2dF:;k k  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 op%?V:  
} [d_sd  
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public void run() CxOBH89(  
{ Lx"a#rZ  
while(nStartPos < nEndPos && !bStop) sC .R.  
{ >%D=#}8l@  
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try{ |e@Bi#M[  
URL url = new URL(sURL); G Riu]   
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); h8yv:}XU*  
httpConnection.setRequestProperty("User-Agent","NetFox"); HGgw<Os-k  
String sProperty = "bytes="+nStartPos+"-"; ]cv|A^  
httpConnection.setRequestProperty("RANGE",sProperty); drQioH-  
Utility.log(sProperty); PUN.nt  
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InputStream input = httpConnection.getInputStream(); !\NKu1ta  
//logResponseHead(httpConnection); adJoT-8P6  
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byte[] b = new byte[1024]; ]rh)AE!Y(  
int nRead; DT=!  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) i`g>Y5  
{ Te{L@sj  
nStartPos += fileAccessI.write(b,0,nRead); $Q:5KNF+p  
//if(nThreadID == 1) X |f'e@  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); o4kNDXP#S  
} /N@0qQ  
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} V4"-;P  
Utility.log("Thread " + nThreadID + " is over!"); *ihg'  
bDownOver = true; |7zm!^t$  
//nPos = fileAccessI.write (b,0,nRead); ubhem(p#  
}  <C4^Vem  
catch(Exception e){e.printStackTrace ();} EMH?z2iGd  
} `.dTkL
 
} ^}8_tZs8\  
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//打印回应的头信息 U[S;5xeF.j  
public void logResponseHead(HttpURLConnection con) ^;YD3EZw  
{ i[ BR"(  
for(int i=1;;i++) 2|~&x~  
{ ?<w +{  
String header=con.getHeaderFieldKey(i); "VWxHRVg4M  
if(header!=null) >?e*;f$VdJ  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); e_6 i896  
Utility.log(header+" : "+con.getHeaderField(header)); JoZC+G  
else xuelo0h,  
break; "0L@cOyG  
} /]xd[^  
} j.CC.[$g  
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public void splitterStop() $zCUQthL@  
{ $)@zlnU  
bStop = true; HIhoYSwB  
} >[xQUf,p  
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} xDr *|d  
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/* fWm;cDM H  
**FileAccess.java wq]nz!  
*//文件访问(定位，写) y i@61XI  
package NetFox; dl{3fldb  
import java.io.*; Mdwh-Cis/  
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. ~|^du<X  
public class FileAccessI implements Serializable{ <{-DYRiN  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 1xtbhk]D  
RandomAccessFile oSavedFile; Vxgc|E^J  
long nPos; ^U_jeAuk8[  
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public FileAccessI() throws IOException E/GI:}YUy_  
{ m dC. FO-  
this("",0); \+Cp<Hv+  
} */8\Z46z  
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public FileAccessI(String sName,long nPos) throws IOException Ra*9d]N@  
{ BLJ-'8G  
oSavedFile = new RandomAccessFile(sName,"rw"); "J{,P9P6  
this.nPos = nPos; 5d4-95['_  
oSavedFile.seek(nPos); -=qmY
f  
} fCV
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 b
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public synchronized int write(byte[] b,int nStart,int nLen) P7
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{ \|&5eeE@  
int n = -1; )O&$-4gL'  
try{ U&eLj"XZ  
oSavedFile.write(b,nStart,nLen); Ns9g>~  
n = nLen; MoFZ  
} |]]fcJOBP  
catch(IOException e) xjX5PQu  
{ OIWo* %  
e.printStackTrace (); $4M3j%S  
} Lq&xlW j  
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return n; z`_N|iEd  
} da<1,hF  
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} A=3U4L  
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/* $ `ho+  
**SiteInfoBean.java . }1!MK5  
*/ BW*zj=N%  
package NetFox; >%[W2L\'  
hmi15VW  
[j/-(?+  
public class SiteInfoBean { (nzzX?`nY  
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private String sSiteURL; //Site's URL j"dbl?og  
private String sFilePath; //Saved File's Path <<xJ-N  
private String sFileName; //Saved File's Name e'?(`yW>  
private int nSplitter; //Count of Splited Downloading File {oZ]1Qf_  
PQs9@]w[  
2KX *x_-  
public SiteInfoBean() }$UFc1He\J  
{//nSplitter的缺省值为5 Av[jF
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//default value of nSplitter is 5 C^~iz in  
this("","","",5); BxG;vS3>*e  
} `<Ftn  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) >9klh-f  
{ = G_6D  
sSiteURL= sURL; j?,$*Fi  
sFilePath = sPath; 0jyokER  
sFileName = sName; 2,fB$5+  
this.nSplitter = nSpiltter; R3<+z  
$200?[  
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} G@;aqe[dB  
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public String getSSiteURL() O//e0?]W  
{ #-`lLI:w0  
return sSiteURL; WZr~Pb9  
} KXGs'D  
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ZAP+jX;  
public void setSSiteURL(String value) F,bl>;{[{  
{ A4^+p0@  
sSiteURL = value; 8?$2;uGL  
} nGt8u4gcP  
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public String getSFilePath() :)z_q!$j  
{ :s5g6TR  
return sFilePath; O<hHo]jLF  
} 3,[2-obmi  
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public void setSFilePath(String value) Dz{e@+>M  
{ YJy*OS_&  
sFilePath = value; 9NT;^K^I  
} i_MI!o  
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public String getSFileName() @FTi*$Ix  
{ cNVdGY%&  
return sFileName; 1 W0;YcT]  
} 0D'Wr(U(  
TU/J]'))C  
aPC!M4#  
public void setSFileName(String value) ~g{,W  
{ )=D&NO67Pq  
sFileName = value; b>i=",i
\  
} nqBuC  
/\#5\dHj  
8syo_sC |  
public int getNSplitter() @K9T )p]  
{ No7Q,p  
return nSplitter; Y[!a82MTzn  
} ]Q3Gj@6  
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zCHr  
public void setNSplitter(int nCount) x3Ud0[(  
{ zgqw*)C~  
nSplitter = nCount; P5>CSWy
%  
} TI>yi ^}  
} tX
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/* h
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**Utility.java fDd!Mt  
*/ <IVz mzpL  
package NetFox; yShHFlO=  
0REWbcxd"  
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public class Utility { 5)UmA8"zVB  
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public Utility() +HX'AC  
{ +]-KzDsr"V  
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))`Zv=y"  
} 9^u?v`!  
qN@a<row&~  
//线程睡眠 o!~
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public static void sleep(int nSecond) to3J@:V8e  
{ d<'xpdxc  
try{ |Z ,G  
Thread.sleep(nSecond); Q7|13^|C  
} !qlGt)G3  
catch(Exception e) mB{{o
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{ ??Zmj:8E'  
e.printStackTrace (); X}(0y  
} ?^~"x.<nr  
} yUO|3ONT  
{ZXC%(u  
//日志 PoJ$%_a}  
public static void log(String sMsg) $hSZ@w|IF  
{ :,m)D775S  
System.err.println(sMsg); BuTIJb+Q\  
} H|UL5<:]D  
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^d80\PXz  
public static void log(int sMsg) :eW~nI.Vc  
{ hli10p$  
System.err.println(sMsg); QIK73^  
} pGY]VwY  
} ?Z>.G{Wm@  
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/* X:lPWz!7{  
**TestMethod.java L]d@D0.Z  
*/ N;'HR)  
package NetFox; s.`d<(X?  
T3./V0]\I  
8[)]3K x  
public class TestMethod { y.p6%E_`  
fm%RNAPvc  
7Zt\G-QV  
public TestMethod() gvNZrp>e!  
{ ///xx/weblogic60b2_win.exe -j_I_  
try{ :(>9u.>l?5  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); -l H>8+  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); .dT;T%3fO  
SiteFileFetch fileFetch = new SiteFileFetch(bean); xGfDz*t  
fileFetch.start(); 87KrSZ  
} c^O#O  
catch(Exception e){e.printStackTrace ();} z,FTsR$x  
8e!DDh  
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} 1?|6odc  
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9
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public static void main(String[] args) lt6
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{ UZP6x2:=  
new TestMethod(); _i
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} 2BDan^:-Av  
} DBJA}Cw  
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