http断点续传简单实现（java)

/* +J}M$eQ  
**SiteFileFetch.java }HzZj;O^2>  
*/ \v<}{\.|$  
package NetFox; 6lGL.m'Ra  
import java.io.*; = zSrre  
import java.net.*; ? "gy`oCv  
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2t'&7>Ys{  
public class SiteFileFetch extends Thread { ))Nc|`  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 5y)kQ
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long[] nStartPos; //开始位置 w K+2;*bI  
long[] nEndPos; //结束位置 D'X'h}+2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 +q(D]:@,[  
long nFileLength; //文件长度 h0`)=  
boolean bFirst = true; //是否第一次取文件 -p1arA  
boolean bStop = false; //停止标志 2;3q](d   
File tmpFile; //文件下载的临时信息 #KwF
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DataOutputStream output; //输出到文件的输出流 (
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） <5.{+!BM  
public SiteFileFetch(SiteInfoBean bean) throws IOException CfAqMH*ip  
{ ]PFc8qv{  
siteInfoBean = bean; AxeWj%w@  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); er_aol e  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); W^x[maz  
if(tmpFile.exists ()) <:p&P  
{ a7Jr} "B  
bFirst = false; REJ}T:  
read_nPos(); v-kH7H"z  
} biJU r^n  
else LRs{nN.N  
{ /swTn1<Y  
nStartPos = new long[bean.getNSplitter()]; k$hWR;U  
nEndPos = new long[bean.getNSplitter()]; 1+^c
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} o)$sZ{` ="  
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} PU8R 0r2k\  
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public void run() H;^6%HV1  
{ TiOvrp7B  
//获得文件长度 aoBM_#  
//分割文件 Nb$)YMbA  
//实例FileSplitterFetch R_^:<F0  
//启动FileSplitterFetch线程 m?csake.Me  
//等待子线程返回 k~?@~xm,R  
try{ Un<~P@T%  
if(bFirst) FnCHbPlb  
{ bZ389dSn  
nFileLength = getFileSize(); -Oo$\=d  
if(nFileLength == -1) |h3YL!  
{ V'9 k;SF  
System.err.println("File Length is not known!"); /q>"">  
} |OC6yN *P)  
else if(nFileLength == -2) shi#K<gVC  
{ ";jhj:Xj  
System.err.println("File is not access!"); Fv3fad@x  
} <mpkkCl,  
else Q{>{ e3z}  
{ $GcVC (]  
for(int i=0;i<nStartPos.length;i++) 4Fnr8 r8W  
{ 1|zo-'y  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ;}r#08I  
} 'a0$74fz  
for(int i=0;i<nEndPos.length-1;i++) `=FfzL  
{ 3c6#?<%0`  
nEndPos = nStartPos[i+1]; ?&N JN/+%  
} 6@bO3K|  
nEndPos[nEndPos.length-1] = nFileLength; @P%&Dha  
} <%|2yPb]  
} -qs9a}iL  
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//启动子线程 ,l~i|_  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; %POoyH@D}  
for(int i=0;i<nStartPos.length;i++) rtOXK4)]I  
{
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), JD,/oL.KA  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Ru2kC} Dx!  
nStartPos,nEndPos,i); xFgY#F  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'sJYt^  
fileSplitterFetch.start(); wVp  
} 2jA-y!(e  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), kvKbl;<&#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); m&fm<?|  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", u3
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nEndPos = " + nFileLength); ,
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// fileSplitterFetch[nPos.length-1].start(); 8nNRn[oS  
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IojF/
 
//等待子线程结束 G9d@vu  
//int count = 0; $o5<#g"/T  
//是否结束while循环
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boolean breakWhile = false; [$f  
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while(!bStop) /djr_T  
{ ~:v" TuuK  
write_nPos(); >}Fe9Y.o  
Utility.sleep(500); Wu?4oF  
breakWhile = true; ``DS?pUY  
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for(int i=0;i<nStartPos.length;i++) \= =rdW-  
{ @.@O#  
if(!fileSplitterFetch.bDownOver) .3M=|rE  
{ ]+Ik/+Nz  
breakWhile = false; Dz3=k
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break; 1>|2B&_^  
} z^'3f!:3   
} %i6i.TF  
if(breakWhile) #+
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break; 1U^;fqvja  
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Z]jm.'@z@  
//count++; krnxM7y  
//if(count>4) B}Qpqa=_c  
// siteStop(); &>,c..Ke  
} jv_z%
`  
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System.err.println("文件下载结束！"); Po_y78ZD  
} [+j}:u  
catch(Exception e){e.printStackTrace ();} SoC3)iqv/  
} Ti:PKpc  
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//获得文件长度 }04EM  
public long getFileSize() D;
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{ 1<766  
int nFileLength = -1; 7.}V
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try{ \k&2nYVHf  
URL url = new URL(siteInfoBean.getSSiteURL()); qJN!L))  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ,E ]vM&  
httpConnection.setRequestProperty("User-Agent","NetFox"); <MdIQ;I8  
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int responseCode=httpConnection.getResponseCode(); jAXKp b  
if(responseCode>=400) +xYU$e6Z  
{ !W2dMD/  
processErrorCode(responseCode); M it3q  
return -2; //-2 represent access is error csK;GSp}  
} wjEyU:  
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String sHeader; m!#'4  
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for(int i=1;;i++) \%BII>VS  
{ [a201I0 -  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); e2F{}N  
//Utility.log(in.readLine()); z}.Q~4 f0D  
sHeader=httpConnection.getHeaderFieldKey(i); 8@rddk  
if(sHeader!=null) Nl$b;~u  
{ T@H<Fm_  
if(sHeader.equals("Content-Length")) ?q{HS&k  
{ Mj!g1Q  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); -}x( MZ  
break; y\?NB:=%  
} 0Ba*"/U]t~  
} 0#y i5U  
else (pv6V2i  
break; |X47&Y  
} }e
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} fug Fk  
catch(IOException e){e.printStackTrace ();} }j`#s  
catch(Exception e){e.printStackTrace ();} ;)Fc@OXN>  
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Utility.log(nFileLength); )`5=6i  
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return nFileLength; G
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} CpLLsphy  
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//保存下载信息（文件指针位置） LS%;ZKJ  
private void write_nPos() 8[rZRc  
{ 01w}8a(  
try{ ?v,4seRuz  
output = new DataOutputStream(new FileOutputStream(tmpFile)); pq +~|  
output.writeInt(nStartPos.length); / n@by4;W  
for(int i=0;i<nStartPos.length;i++) IeT1Jwe  
{ $N/"c$50,  
// output.writeLong(nPos); \f4JIsZ-&  
output.writeLong(fileSplitterFetch.nStartPos); #-7w|  
output.writeLong(fileSplitterFetch.nEndPos); \5DOp-2  
} ZTzh[2u*  
output.close(); |2!cPf^8  
} ydMfV-  
catch(IOException e){e.printStackTrace ();} _>u0vGF-  
catch(Exception e){e.printStackTrace ();} 1X-fiQJe  
} W.m2`] &  
:9]"4ktoJ  
=z4kK_?F,  
//读取保存的下载信息（文件指针位置） "JpnmE[`  
private void read_nPos() iM_Zn!|@\  
{ L(`Rf0smt  
try{ Bhf4 /$  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); k.6(Q_TS  
int nCount = input.readInt(); wvz_)bN~A  
nStartPos = new long[nCount]; 7-j=he/  
nEndPos = new long[nCount]; <2ymfL-q  
for(int i=0;i<nStartPos.length;i++) L4!T  
{ nO;t5d  
nStartPos = input.readLong(); l'FNp  
nEndPos = input.readLong(); bR}=bp4K  
} )ua
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input.close(); /2Qgg`^)  
} !9g>/9h  
catch(IOException e){e.printStackTrace ();} JG*Lc@Q  
catch(Exception e){e.printStackTrace ();} %y[ t+)!E  
} '[`pU>9  
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private void processErrorCode(int nErrorCode)
]#P>wW  
{ <?Y.w1  
System.err.println("Error Code : " + nErrorCode); -iySU 6  
} UlH;0P?  
*,#T&M7D  
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//停止文件下载 ;H`>jI$  
public void siteStop() W8Aii'Q8C/  
{ zOT(>1'  
bStop = true; L%5g]=  
for(int i=0;i<nStartPos.length;i++) gQlL0jAV  
fileSplitterFetch.splitterStop(); -=VGXd  
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} gvy c(d  
} 3!2TE-  
//负责部分文件的抓取  HV\l86}  
**FileSplitterFetch.java ;6/dFOZn  
*/ NTy0NH  
package NetFox; v|#}LQZ  
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import java.io.*; {n-6e[  
import java.net.*; \8iWcqJktN  
!)+8:8H'  
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public class FileSplitterFetch extends Thread { Hribk[99  
WJF#+)P:Y  
=.yKl*WV{  
String sURL; //File URL Y/Q/4+  
long nStartPos; //File Snippet Start Position 8"KaW2/%  
long nEndPos; //File Snippet End Position 6ujePi <U  
int nThreadID; //Thread's ID ?h7(,39^>  
boolean bDownOver = false; //Downing is over >uVr;,=y  
boolean bStop = false; //Stop identical %:vMD  
FileAccessI fileAccessI = null; //File Access interface }RN&w]<  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException %VmHw~xyF:  
{ UCL aCt -  
this.sURL = sURL; _7Rp.)[&  
this.nStartPos = nStart; o<\9OQ0  
this.nEndPos = nEnd; <j^bk"l p  
nThreadID = id; 7qT>wCVT  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 U3 y-cgE  
} ?
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public void run() Yk!TQY4  
{ uIb,n5  
while(nStartPos < nEndPos && !bStop) \g<=n&S?  
{ _pe_w{V-b6  
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try{ j& ~`wGM  
URL url = new URL(sURL); QGpAG#M9?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); YNV4'  
httpConnection.setRequestProperty("User-Agent","NetFox"); +8~C&K:  
String sProperty = "bytes="+nStartPos+"-"; QfHO3Y6h[  
httpConnection.setRequestProperty("RANGE",sProperty); ?O.1HEr  
Utility.log(sProperty); Mpu8/i gX,  
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InputStream input = httpConnection.getInputStream(); Vp~c$y+  
//logResponseHead(httpConnection); ?OFl9%\ V  
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byte[] b = new byte[1024]; Kfl#78$d  
int nRead; 9/_F  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) b w2KD7  
{ : ZWKrnG  
nStartPos += fileAccessI.write(b,0,nRead); 3sy|pa  
//if(nThreadID == 1) |NoTwK  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); N+M^e`H  
} |A0)-sVZ  
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Utility.log("Thread " + nThreadID + " is over!"); {ICW"Rlcs  
bDownOver = true; H$o=kQN  
//nPos = fileAccessI.write (b,0,nRead); yl'@p5n  
} ?5e
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catch(Exception e){e.printStackTrace ();} $VRVMY [q  
} <yq kJ  
} yoc;`hO-  
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//打印回应的头信息 xq<3*Bcw  
public void logResponseHead(HttpURLConnection con) <*'%Xgm  
{ HZDeQx`*s  
for(int i=1;;i++) vz1yH%~E  
{ -fm1T|>#  
String header=con.getHeaderFieldKey(i); bh&Wy<Y  
if(header!=null) Or9"T]z  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); pdFa]  
Utility.log(header+" : "+con.getHeaderField(header)); RL|d-A+;  
else m2|%AD  
break; V@C8HTg  
} 4 [K"e{W3  
} 6#SUfK;  
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public void splitterStop() ^ b`wf"A  
{ g;n6hXq4  
bStop = true; 4J9VdEKk  
} 3<%ci&B  

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} &Fg|52  
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m
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/* 49?wEm#  
**FileAccess.java :Q-QY)hH  
*//文件访问(定位，写) S8Ec.]T  
package NetFox; dWK"Tkf\  
import java.io.*; q4y sTm  
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public class FileAccessI implements Serializable{ >f*-9  
nd#owjB  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Hq;*T3E  
RandomAccessFile oSavedFile; =v:}{~M^$  
long nPos; F>lM[Lu#  
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public FileAccessI() throws IOException T jrz_o)  
{ rf=oH }  
this("",0); ?[!_f$50]P  
} |QHIB?C?`  
F"| ;  
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public FileAccessI(String sName,long nPos) throws IOException K3.z>.F'h  
{ Min{&?a  
oSavedFile = new RandomAccessFile(sName,"rw"); >Hwf/Gf[  
this.nPos = nPos; J
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oSavedFile.seek(nPos); 6c[Slq!KA  
} K +l-A>Ic  
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:2*0Jh3_  
public synchronized int write(byte[] b,int nStart,int nLen) #9rCF 3P  
{ !IC@^kkh{  
int n = -1; Txa 2`2t
7  
try{ cMoBYk  
oSavedFile.write(b,nStart,nLen); SNrX(V::z  
n = nLen; otmyI;v 7<  
} U&o~U] rm  
catch(IOException e) `1i\8s&O6@  
{ b>@fHmpwD  
e.printStackTrace (); CuFlI?~8 z  
} 0 } |21YED  
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return n; $VJE&b  
} ^%t{:\  
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} bC,SE*F\  
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/* c8oE,-~  
**SiteInfoBean.java 7,3 g{
8  
*/ asJt6C  
package NetFox; %:.IG.`d  
:MILOwF  
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public class SiteInfoBean { &`}ACTY'P  
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private String sSiteURL; //Site's URL oR}'I  
private String sFilePath; //Saved File's Path N6h.zl&04  
private String sFileName; //Saved File's Name =`t%p1   
private int nSplitter; //Count of Splited Downloading File W:1GY#Pe  
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public SiteInfoBean() !$!"$-5  
{//nSplitter的缺省值为5 vqRW^>~-B  
//default value of nSplitter is 5 0c]3 
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this("","","",5); WZf}1.Mh*  
} WO+_|*&  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) rlSflcK\\(  
{ Wa'
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sSiteURL= sURL; }>?"bcJ  
sFilePath = sPath; c59l/qoz  
sFileName = sName; YvPs  
this.nSplitter = nSpiltter; 9 [wR/8Xm  
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} f/]g@/`  
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public String getSSiteURL() uDG#L6  
{ 8\rHSsP  
return sSiteURL; vY(xH>Fd  
} 'fIirGOl  
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public void setSSiteURL(String value) \bumB<w(]  
{ J2Eb"y>/;  
sSiteURL = value; P:2 0i*QU  
} 5Y(f7,JX  
l;'c6o0e  
uNG?`>4>  
public String getSFilePath() jl~?I*Gr  
{ \!,qXfTMB  
return sFilePath; 3qBZzM O*  
} /WE1afe_R  
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U#1,]a\  
public void setSFilePath(String value) PV/SzfvIq  
{ kc-v(WIC  
sFilePath = value; gTwxmp.,  
} aC=D_JJ
\  
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PK|"+I0  
public String getSFileName() >s+*D=k  
{ 0s8w)%4$  
return sFileName; (lR9x6yf  
} L/n?1'he  
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7iBN!"G0  
public void setSFileName(String value) 298@&_  
{ $C8nPl' 7  
sFileName = value; J)leRR&  
} Zjx:1c= b  
QSq0{  
}Pn]j7u!  
public int getNSplitter() 1O,<JrE+-  
{ I?!7]Sn$  
return nSplitter; ET 2@dY~  
} sHQ82uX  
mIX[HDy:V$  
w `0m[*  
public void setNSplitter(int nCount) "`4V^1  
{ $D)Ajd;  
nSplitter = nCount;  *c6o#[l  
} b qNM  
} &?xZHr`  
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/* Gn8'h TM  
**Utility.java yMoV|U6  
*/ _pS|bqF  
package NetFox; c_#+xGS!7  
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.sOEqwO}>  
public class Utility { $+$S}i=  
t+?m<h6w;l  
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public Utility() $|V@3`0  
{ J>XMaI})U  
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} j
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B3V;  
//线程睡眠 (6Tvu
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public static void sleep(int nSecond) L H8iHB  
{ @z-%:J/$  
try{ Z=&cBv4Fs  
Thread.sleep(nSecond); d~F4  
} ^f%hhp
V@  
catch(Exception e) r$ 8^K\oF  
{ bk}'wcX<+]  
e.printStackTrace (); 4ru-qF  
} tvlrUp  
} f"}g5eg+  
w4fz!l]  
//日志 ~]_U!r[FA  
public static void log(String sMsg) <lo\7p$A  
{ ZZu{ct9  
System.err.println(sMsg); QK`5KB(k'  
} &{uj3s&C   
T{:~v+I=  
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public static void log(int sMsg) R0A|}Ee*  
{ fR$_=WWN>h  
System.err.println(sMsg); f
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} (E{}iq@2  
} 6^l|/\Y{  
"!w#E6gU  
R9z:K_d,  
/* tg%#W`  
**TestMethod.java ?bH&F  
*/ Kt#_Ln_6  
package NetFox; K!,T.qA&=  
yCvP-?2  
|8q:sr_  
public class TestMethod { j"F?^0aR,Q  
H-&T)  

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public TestMethod() {U'\2Ge<m  
{ ///xx/weblogic60b2_win.exe 'EHtA9M  
try{ v6M4KC2?  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); VtN1
[}  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); *671MJ9  
SiteFileFetch fileFetch = new SiteFileFetch(bean); )UCc!  
fileFetch.start(); n "bii7h  
} hGy[L3{  
catch(Exception e){e.printStackTrace ();} 7,lnfCm H  
;l %$-/%  
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} 64i*_\UKe  
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public static void main(String[] args) s(Bcw`'#  
{ hp1+9vEN  
new TestMethod(); :pfLa2f+  
} _70Z1_;  
} 8c\\-{  
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