http断点续传简单实现（java)

/* hT=E~|O  
**SiteFileFetch.java *W |  
*/ %A `9[icy  
package NetFox; r8y,$Mv<)0  
import java.io.*; 4t*VI<=<[  
import java.net.*; \K2S.j  
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public class SiteFileFetch extends Thread { KxmB$x5-=8  
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SiteInfoBean siteInfoBean = null; //文件信息Bean (8S+-k?  
long[] nStartPos; //开始位置 h{]0 H'g  
long[] nEndPos; //结束位置 +;@R&Y  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 KdlUa^}
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long nFileLength; //文件长度 V?MaI.g
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boolean bFirst = true; //是否第一次取文件 ]*DIn1C^  
boolean bStop = false; //停止标志 =AK6^v&on  
File tmpFile; //文件下载的临时信息 Z~ q="CA4  
DataOutputStream output; //输出到文件的输出流 IH=%%AS  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） v>hc\H1P  
public SiteFileFetch(SiteInfoBean bean) throws IOException o9D#d\G  
{ l Hu8ADva  
siteInfoBean = bean; v~^*L iP+  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); v{SYz<(  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); q|B.@Ng.  
if(tmpFile.exists ()) <ihJp^kgQ  
{ 6XhS g0s  
bFirst = false;  #s=\  
read_nPos(); @MH/efW.  
} /ubGa6N  
else (:#4{C  
{ ac43d`wpK  
nStartPos = new long[bean.getNSplitter()]; 8(6mH'^y  
nEndPos = new long[bean.getNSplitter()]; %[?{H} y  
} Qmv8T ^+  
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} "y .(E7 6  
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public void run() o[G,~f\-  
{ ~:4Mf/Ca  
//获得文件长度 SP|Dz,o  
//分割文件 #0M,g  
//实例FileSplitterFetch rYA4(rYq  
//启动FileSplitterFetch线程 X2('@Yh  
//等待子线程返回 wdgC{WGl  
try{ _@]@&^K$E  
if(bFirst) `ucr;P  
{ ;fY)7 '  
nFileLength = getFileSize(); ~
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if(nFileLength == -1) 4[LzjC  
{ !8%{(;(  
System.err.println("File Length is not known!"); 7[7Sm^Tw  
} z:tu_5w!,  
else if(nFileLength == -2) pdR&2fp  
{ /I' np  
System.err.println("File is not access!"); u/74E0$S  
} r`=!4vY2  
else !P* z=  
{ S|v-lJ/I  
for(int i=0;i<nStartPos.length;i++) WXE{uGc  
{ R$40cW3`  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); L}U fd >*  
} `ZAGseDd~  
for(int i=0;i<nEndPos.length-1;i++) !bD`2m[Q  
{ RiAY>:  
nEndPos = nStartPos[i+1]; g~=#8nJ  
} 8:0.Pi(ln@  
nEndPos[nEndPos.length-1] = nFileLength; a@WSIcX*W  
} WAbt8{$D  
} ?IV3"\5  
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//启动子线程 ijWn,bj  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; mH} 1Zy  
for(int i=0;i<nStartPos.length;i++) ,a,coeL  
{  ^'c[HVJ  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), {p(.ckze+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), i;B)@op.#  
nStartPos,nEndPos,i); {oN7I'>  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -^LEGKN  
fileSplitterFetch.start(); 6~0.YZ9  
} t.oP]_mI  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), s4c2  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Rm!Iv&{  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Li_ a|dI  
nEndPos = " + nFileLength); JB= L\E}  
// fileSplitterFetch[nPos.length-1].start(); sIh,@
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!j?2HlIK+  
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//等待子线程结束 Y/_b~Ahn  
//int count = 0; d^W
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//是否结束while循环 miZ&9m  
boolean breakWhile = false; pTlNJ!U>  
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while(!bStop) bO%bMZWB!y  
{ ca1A9fvo  
write_nPos(); mmG+"g$|  
Utility.sleep(500); />zE$)'M  
breakWhile = true; bytAdS$3  
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for(int i=0;i<nStartPos.length;i++) s`G3SE  
{ |Tp>,\:5  
if(!fileSplitterFetch.bDownOver) +,"/z\QO  
{ gUB%6vG\I  
breakWhile = false; ZV
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break; C&m[/PJ~l  
} 195m0'zda  
} 2\M^_x$N  
if(breakWhile) j\D_Z{m2  
break; *94<rlh{"  
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//count++; 2n]Br  
//if(count>4) )8:Ltn%  
// siteStop(); lV-b  
} YULI y-W  
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System.err.println("文件下载结束！"); f\}fUg2  
} c-L1 Bkw  
catch(Exception e){e.printStackTrace ();} 6;g"`l51  
} c_e2'K:  
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//获得文件长度 \s8j*  
public long getFileSize() ~5[#c27E9  
{ -lL(:drn  
int nFileLength = -1; ^#T@NN0T  
try{ #MbkU])  
URL url = new URL(siteInfoBean.getSSiteURL()); ) N*,cTE  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); gwj+~vSfi  
httpConnection.setRequestProperty("User-Agent","NetFox"); 3: 'eZcM  
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int responseCode=httpConnection.getResponseCode(); XrY\ot`,D  
if(responseCode>=400) KErQCBeJ  
{ [%M=n
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processErrorCode(responseCode); N,
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return -2; //-2 represent access is error B zmmE2~*  
} uz6S7I  
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String sHeader; 0drt,k  
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' XJ>;",[  
for(int i=1;;i++) PT
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{ t'e1r&^:r~  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); p.1@4kgK&r  
//Utility.log(in.readLine()); Ib(q9!L  
sHeader=httpConnection.getHeaderFieldKey(i); fk5xIW  
if(sHeader!=null) OT[&a6_  
{ ?/Bp8q(  
if(sHeader.equals("Content-Length")) =]k0*\PS  
{ _?"P<3/iF  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); @N,(82k  
break; o gec6u}  
} TUw+A6u:p  
} zPzy0lx  
else 9Z.Xo kg  
break; OPVF)@"ptM  
} {t<E*5N]a  
} .ME>ICA  
catch(IOException e){e.printStackTrace ();} AgEX,SPP  
catch(Exception e){e.printStackTrace ();} rucgav  
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Utility.log(nFileLength); (X=JT  
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return nFileLength; B2p/  
} :w|ef;  
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//保存下载信息（文件指针位置） +ZFw3KEkz  
private void write_nPos() _{Q)5ooP  
{ :G3PdQb^  
try{ t1Ty.F)r  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ENZjRf4  
output.writeInt(nStartPos.length); =E6ND8l@2  
for(int i=0;i<nStartPos.length;i++) *0vq+C  
{ >6Y@8 )  
// output.writeLong(nPos); ,z4)A&F[c;  
output.writeLong(fileSplitterFetch.nStartPos); \wMqVRPoQ  
output.writeLong(fileSplitterFetch.nEndPos); > 2)@(f~g  
} JXFPN|  
output.close(); 3jSt&+  
} W|X=R?*ZK  
catch(IOException e){e.printStackTrace ();} JWZG)I]r  
catch(Exception e){e.printStackTrace ();} ltQo_k  
} Y-yozt  
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//读取保存的下载信息（文件指针位置） s#Os?Q?  
private void read_nPos()
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{ P
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try{ hn`yc7<}(u  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 7
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int nCount = input.readInt(); A9 *P7  
nStartPos = new long[nCount]; ]A?(OA  
nEndPos = new long[nCount]; xUW\P$  
for(int i=0;i<nStartPos.length;i++) [TX1\*W  
{ u[:-^H  
nStartPos = input.readLong(); rY?]pMp  
nEndPos = input.readLong(); ()'yY^   
} WiU-syNh  
input.close(); ttP|}|O  
} 1U)U{i7j  
catch(IOException e){e.printStackTrace ();} u~O9"-m !V  
catch(Exception e){e.printStackTrace ();} 84f(BE  
} 'c7'iDM  
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private void processErrorCode(int nErrorCode) $?Km3N\?v  
{ 4h*c{do  
System.err.println("Error Code : " + nErrorCode); ]EN+^i1F[  
} ]F{F+r  
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//停止文件下载 pyw]ydB  
public void siteStop() 'G1~ A +  
{ YD9|2S!G  
bStop = true; q!10G  
for(int i=0;i<nStartPos.length;i++)  l;;,[xhq  
fileSplitterFetch.splitterStop(); dz6&TdEl  
*KV^X(/  
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} >b7Yk)[%  
} PIHix{YR  
//负责部分文件的抓取 8l>7=~Egp  
**FileSplitterFetch.java W-RqooEv  
*/ +@^FUt=tq  
package NetFox; <@S'vcO  
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import java.io.*; &q7}HO/ @  
import java.net.*; Gh5 3Pne  
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public class FileSplitterFetch extends Thread {  ^:^  
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String sURL; //File URL pzT,fmfk  
long nStartPos; //File Snippet Start Position F! [Gj%~I  
long nEndPos; //File Snippet End Position t`- [  
int nThreadID; //Thread's ID &c^tJ-s  
boolean bDownOver = false; //Downing is over 5oe{i/#di  
boolean bStop = false; //Stop identical 5yL\@7u`  
FileAccessI fileAccessI = null; //File Access interface *DgRF/S  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException W5uC5C*,l  
{ hg7_ZjO  
this.sURL = sURL; `l'Ine11  
this.nStartPos = nStart; en"\2+{Cg  
this.nEndPos = nEnd; .wO-2h{Q  
nThreadID = id; /s~BE ,su  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 _G$21
=  
} ?>
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public void run() lMmP]{.>$  
{ Nh01NY;  
while(nStartPos < nEndPos && !bStop) pK"iTc#\X  
{ M_O)w^ '  
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try{ G|I}x/X"Q7  
URL url = new URL(sURL); !S'!oinV  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); L0R$T=~%)  
httpConnection.setRequestProperty("User-Agent","NetFox"); )43z(:<  
String sProperty = "bytes="+nStartPos+"-"; t>2EZ{N+y  
httpConnection.setRequestProperty("RANGE",sProperty); t~|`RMn"  
Utility.log(sProperty); !ir%Pz^)  
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InputStream input = httpConnection.getInputStream(); \8)FVpS  
//logResponseHead(httpConnection); Us\Nmso z  
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byte[] b = new byte[1024]; oT!i}TW?o  
int nRead; :7*9W|e  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ,ZZ5A;)  
{ +Mb}70^  
nStartPos += fileAccessI.write(b,0,nRead); vs{
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//if(nThreadID == 1) Ri3*au/
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); yb-4[C:i  
} T3Sz<K$E  
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Utility.log("Thread " + nThreadID + " is over!"); wkY$J\J  
bDownOver = true; ba)hWtenH  
//nPos = fileAccessI.write (b,0,nRead); Zul@aS !  
} ~i]4~bkH2  
catch(Exception e){e.printStackTrace ();} }((P)\s
  
} oz%{D@CF  
} ^}UFtL i  
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//打印回应的头信息 lSy_cItF  
public void logResponseHead(HttpURLConnection con) (ylZ[M&B:  
{ ?weuq"*a  
for(int i=1;;i++) +1a2Un  
{ :|-^et]a8  
String header=con.getHeaderFieldKey(i); S3Fj /2Q8  
if(header!=null) Lie= DD  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); sRQ4pnnrn  
Utility.log(header+" : "+con.getHeaderField(header)); 1I%niQv5t  
else V"T5<HA9  
break; [xXV5 JU
 
} z`YAOhD*h4  
} \okvL2:!  
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public void splitterStop() Hn]6re  
{ z3M6<.K  
bStop = true; ,nWZJ&B  
} 'X
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} ! QKec  
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/* -h21  
**FileAccess.java 91ec^g  
*//文件访问(定位，写) o}Zl/&(  
package NetFox; jF{)2|5  
import java.io.*; Pu}PE-b  
}7i}dyQv}  
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public class FileAccessI implements Serializable{ sh%%U  
#B__-"cRv  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 5 HN,y  
RandomAccessFile oSavedFile; 6W'2w?qj?4  
long nPos; hOe$h,E']  
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public FileAccessI() throws IOException 3ZqtIQY`  
{ T_qh_L3  
this("",0); |99Z& <8f  
} (N{  
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public FileAccessI(String sName,long nPos) throws IOException PU%WpI.w  
{ aT=V/Xh}d  
oSavedFile = new RandomAccessFile(sName,"rw"); yjucR Fl  
this.nPos = nPos; 'x=y:0A  
oSavedFile.seek(nPos); Q
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} ]2xoeNF/W{  
@_?8I_\:  
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public synchronized int write(byte[] b,int nStart,int nLen) ntF#x.1Pm  
{ ]K%D$x{+\  
int n = -1; s`,.&  
try{ `pXC= []B2  
oSavedFile.write(b,nStart,nLen); r<.*:]L
 
n = nLen; @3>nVa  
} nb|"dK|  
catch(IOException e) wqp(E+&  
{ $]iRfXv,l!  
e.printStackTrace (); ]I0(_e|z}  
} g$S<_$Iey  
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return n; XJf1LGT5  
} O[
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} [u`9R<>c"U  
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/* As*59jkB  
**SiteInfoBean.java "a>a "Ei  
*/ veGRwir  
package NetFox; (`Q_^Bfyl  
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public class SiteInfoBean { pn2_ {8.  
H>5@/0cL2  
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private String sSiteURL; //Site's URL (#k2S-5  
private String sFilePath; //Saved File's Path lr@H4EJ{  
private String sFileName; //Saved File's Name 8fs::}0  
private int nSplitter; //Count of Splited Downloading File GGchNt  
699
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{!vz 6QDS  
public SiteInfoBean() iG;GAw|
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{//nSplitter的缺省值为5 EYF]&+ 9  
//default value of nSplitter is 5 Qw
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this("","","",5); r`(U3EgP  
} zbL6TP@=  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) h|Uy!?l  
{ UBxQ4)%  
sSiteURL= sURL; ssC5YtF7X  
sFilePath = sPath; />9?/&N6"  
sFileName = sName; c/E6}OWA  
this.nSplitter = nSpiltter; k"2xyzt*  
/.aDQ>  
JM
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} #0j,1NpL  
P9D'L{yS/x  
JRj%d&^}  
public String getSSiteURL() MM%c  
{ Ka\%kB>*`  
return sSiteURL;  !(<Yc5  
} 3_tO  
i;$'haK<  
hol54)7$3:  
public void setSSiteURL(String value) =1"8
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{ Y-WYQ{  
sSiteURL = value; l`R/
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} 0oi =}lV  
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>K9uwUi|b]  
public String getSFilePath() ]='E&=nc  
{ z_p/.kQ'5  
return sFilePath; NwdA@"YQ|  
} Y?z@)cL  
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6Hn3  
public void setSFilePath(String value) /IC7q?avQN  
{ +)fl9>Mb  
sFilePath = value; $Q|t^(  
} dviL5Eaj  
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public String getSFileName() n(b(H`1n  
{ MD,}-m  
return sFileName; GiN\nu<!  
} Z?5kO-[  
5u\si4BL{  
~Cj55S+  
public void setSFileName(String value) Nd~?kZZu  
{ -zd*tujx  
sFileName = value; 451r!U1Z  
} !z;a>[T'  
+t
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public int getNSplitter() y.~y*c6,g  
{ 1Q6WpS  
return nSplitter; MX?K3=j @>  
} V>j6Juh  
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public void setNSplitter(int nCount) x(z[S$6Y\  
{ 9psX"*s  
nSplitter = nCount; Dm6}$v'0  
} Cd#>,,\z  
} '@M  
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/* $LZf&q:\]*  
**Utility.java ]+W+8)f1M  
*/ Nf>1`eP  
package NetFox; E{d Mdz  
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public class Utility {
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public Utility() W 0Q-&4  
{ :QsGwhB  
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} d+%1q
 
zqqpBwk#  
//线程睡眠 4em7PmT  
public static void sleep(int nSecond) =8j;!7p  
{ . x~tEe  
try{ O9]j$,i  
Thread.sleep(nSecond); 0,(U_+n  
} (
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catch(Exception e) ,*r"cmz  
{ C8y 3T/G  
e.printStackTrace (); 3Qe:d_  
} Bm%:Qc*  
} YcGSZ0vQ  
kqSCKY1  
//日志 L._I"g5 H9  
public static void log(String sMsg) 7[QU *1bk  
{ er^z:1'  
System.err.println(sMsg); B}gi /  
} e%j+,)Ry  
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:N%cIxrqP  
public static void log(int sMsg) Nc[>CgX"@  
{ &Hc8u,|  
System.err.println(sMsg); 5SK{^hw  
} r~u/M0h `  
} ?{$Q'c_I  
U n2xZ[4  
X_|8CD-@6  
/* AShJtxxa  
**TestMethod.java '+Dn~8Y+9  
*/ xzy7I6X  
package NetFox; D*`|MzlQ  
6J6MR<5'  
42:\1B#[  
public class TestMethod { &6PZX0M  
lKI1bs]i  
vyERt^z  
public TestMethod() i=reJ(y-  
{ ///xx/weblogic60b2_win.exe s7S
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try{ V{$(#r  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 0X`Qt[  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 3ZU`}  
SiteFileFetch fileFetch = new SiteFileFetch(bean); S3:Pjz}t  
fileFetch.start(); RqXcL,,9  
} DL|,:2`  
catch(Exception e){e.printStackTrace ();} u1ggLH!U  
[U]*OQH`e  
wQ*vcbQX*  
} Jj|HeZ1C f  
6~0S%Hz   
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public static void main(String[] args) )}=`Gx5+  
{ NUEy0pLw  
new TestMethod(); ~o= Sxaf  
}
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} IBf&'/ 8\  
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