http断点续传简单实现（java)

/* QTIC5cl,  
**SiteFileFetch.java
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*/ PfN[)s4F{R  
package NetFox; ':d9FzGKa  
import java.io.*; cGM?r}zJ  
import java.net.*; YZy%]i=1  
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public class SiteFileFetch extends Thread { /?%1;s:'  
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SiteInfoBean siteInfoBean = null; //文件信息Bean &BxZ}JH=k  
long[] nStartPos; //开始位置 je;|zfe]  
long[] nEndPos; //结束位置 ^wlo;.8Y  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 cqG&n0zb  
long nFileLength; //文件长度 /0YO`])"  
boolean bFirst = true; //是否第一次取文件 :h8-y&;  
boolean bStop = false; //停止标志 Gp0yRT.  
File tmpFile; //文件下载的临时信息 G-[.BWQ   
DataOutputStream output; //输出到文件的输出流 Ex+E66bE  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） KY+BXGW*  
public SiteFileFetch(SiteInfoBean bean) throws IOException h4E[\<?  
{ a}g<<{  
siteInfoBean = bean; 24I\smO  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +>QD4z#  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); )}to7r7`  
if(tmpFile.exists ()) 9P& \2/ {  
{ 63SmQsv  
bFirst = false; +W+o~BE  
read_nPos(); Hto+
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} PUEEfq!%  
else 4Z0Y8y8)  
{ wCt!.<, .  
nStartPos = new long[bean.getNSplitter()]; 'M35L30  
nEndPos = new long[bean.getNSplitter()]; f{j`d&|  
} ]D<3yIGS  
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} /s Bs eI  
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public void run() LMaY}m>  
{ :Izdj*HL;A  
//获得文件长度 GhR%fxe  
//分割文件 AP9>_0=  
//实例FileSplitterFetch (5GjtFojY|  
//启动FileSplitterFetch线程 "+A8w  
//等待子线程返回 om{aws;  
try{ o&R
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if(bFirst) 9'0v]ar  
{ !'(
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nFileLength = getFileSize(); -eFq^KP2  
if(nFileLength == -1) )Ec /5=A  
{ E`#/m@:|-  
System.err.println("File Length is not known!"); @n;$Edza/  
} yk/BQ|G  
else if(nFileLength == -2) &%;K_asV;  
{ YSr
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System.err.println("File is not access!"); 
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} Ap!Y 3C  
else qS[KB\RN1  
{ ZjveXrx  
for(int i=0;i<nStartPos.length;i++) fl+2'~  
{ Yu:!l>  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); s:*" b'  
} !"SuE)WM  
for(int i=0;i<nEndPos.length-1;i++) Lnc>O'<5P9  
{ [!YSW'  
nEndPos = nStartPos[i+1]; SquuK1P=  
} -d*je{c|  
nEndPos[nEndPos.length-1] = nFileLength; <xh";seL  
} 78kT}kgW  
} -DWnDku8=  
CD pLV:  
\@$V^;OP/  
//启动子线程 &5n0J  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Qsg([K  
for(int i=0;i<nStartPos.length;i++) wZb77  
{ Qq<+QL|
 
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), eT@,QA(3  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), k? !'OHmBL  
nStartPos,nEndPos,i); s!?T$@a=  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); lr9s`>9  
fileSplitterFetch.start(); >#|%y>g .o  
} PvW~EJ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), }TG=ZVi  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); =j~Xrytn  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", jd+U+8r  
nEndPos = " + nFileLength); f5,!,]XO  
// fileSplitterFetch[nPos.length-1].start(); sh;>6xB  
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//等待子线程结束 @(any^QJ  
//int count = 0;
dCO)"]  
//是否结束while循环 gUrXaD#  
boolean breakWhile = false; a[7Lqu  
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while(!bStop) 5^Ps(8VbS  
{ _e$T'*q  
write_nPos(); q]wP^;\Jl  
Utility.sleep(500); GI)eq:K_U8  
breakWhile = true; S\ ) ~9?  
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for(int i=0;i<nStartPos.length;i++) V]P%@<C  
{ VP_S[+Zv~  
if(!fileSplitterFetch.bDownOver) qx`)M3Mu|<  
{ f~{4hVA  
breakWhile = false; E\vW>g*W  
break; M5c~-}Ay  
} UJk/Lxv  
} -P-&]F5  
if(breakWhile) -P We  
break; ,m1F<Pdts  
M6H#Y2!ZbC  
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//count++; Y(6p&I  
//if(count>4) 9K4Jg]?  
// siteStop(); DGO\&^GT^  
} fl o9iifZ  
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System.err.println("文件下载结束！"); {vU;(eN  
} 0 ![  
catch(Exception e){e.printStackTrace ();} 0%"
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} Q3 yW#eD  
#9(L/)^  
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//获得文件长度 @<C<rB8R  
public long getFileSize() p #
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{ fm$)?E_Rp  
int nFileLength = -1; -gVsOX0  
try{ OpFm:j3  
URL url = new URL(siteInfoBean.getSSiteURL()); B-W8Zq#4>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); L% `lC]  
httpConnection.setRequestProperty("User-Agent","NetFox"); !uSG 1j"y  
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int responseCode=httpConnection.getResponseCode(); >6A8+=  
if(responseCode>=400) LyG&FOf?  
{ rvp#[RAaS}  
processErrorCode(responseCode); [xHHm5$  
return -2; //-2 represent access is error MhZ\]CAs9  
} d#
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%IK[d#HO  
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String sHeader; =jkiM_<h  
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for(int i=1;;i++) ]B3f$;W  
{ ;P9cjfSn  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); @=dwvl' W  
//Utility.log(in.readLine()); 89\DS!\x9  
sHeader=httpConnection.getHeaderFieldKey(i); ` *q>E  
if(sHeader!=null) ~;yP{F8?  
{ @3Gr2/a  
if(sHeader.equals("Content-Length")) s_%KWkS  
{ E@_]L<Z  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); `]j:''K  
break; bz|-x"qk  
} dT'd C  
} ?XB[awTD~  
else R_2T"  
break; H&!?c5  
} =pd#U  
} giORc   
catch(IOException e){e.printStackTrace ();} -^$`5Rk  
catch(Exception e){e.printStackTrace ();} Sd+bnq%  
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Utility.log(nFileLength); q.!<GqSgb  
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return nFileLength; ]i Yp  
} +jb<=ERV[  
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//保存下载信息（文件指针位置） %![3?|8~  
private void write_nPos() T,/:5L9  
{ =:_DXGW2H  
try{ 9y?)Ga  
output = new DataOutputStream(new FileOutputStream(tmpFile)); odhcU5  
output.writeInt(nStartPos.length); wf2v9.;X:<  
for(int i=0;i<nStartPos.length;i++) &NH[b1NMr  
{ u#nM_UJe  
// output.writeLong(nPos); Dy|)u1?  
output.writeLong(fileSplitterFetch.nStartPos); 'f-8P  
output.writeLong(fileSplitterFetch.nEndPos); /Jf}~}JP  
}  >G}g=zy@  
output.close(); Jsf"h-)P  
} $3]]<oH  
catch(IOException e){e.printStackTrace ();} SGP)A(,k9  
catch(Exception e){e.printStackTrace ();} 9i+.iuE%Bu  
} ndHUQ$/(  
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//读取保存的下载信息（文件指针位置） ;VS$xnZ  
private void read_nPos() mOfTq] @B  
{ sw+vyBV)r  
try{ 1.I58(0~+  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); f"R'Q|7D  
int nCount = input.readInt(); 5+[ 3@  
nStartPos = new long[nCount]; MJ<jF(_=  
nEndPos = new long[nCount];  6h?)x  
for(int i=0;i<nStartPos.length;i++) s@(ME1j(U!  
{ \S0QZQbz/  
nStartPos = input.readLong(); {<Y\flj{@m  
nEndPos = input.readLong(); )4^Sz&\  
} S`pBEM  
input.close(); C_;A~iI7
 
} dfT  
catch(IOException e){e.printStackTrace ();} /a}` y  
catch(Exception e){e.printStackTrace ();} K)W:@,*  
} ZKt`>KZ  
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:gTtWJ04]  
private void processErrorCode(int nErrorCode) `X%Qt~  
{ @t2S"s$m  
System.err.println("Error Code : " + nErrorCode); _K3;$2d|R  
} =w ! 6un  
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//停止文件下载 sB wzb  
public void siteStop() .4[M7)  
{ D[dI_|59a  
bStop = true; [F+*e=wjN>  
for(int i=0;i<nStartPos.length;i++) o^W.53yX  
fileSplitterFetch.splitterStop(); ,j(S'Pw  
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} tHV+#3h  
} v]y=+* A  
//负责部分文件的抓取 y wmC>`0p  
**FileSplitterFetch.java [:8+ +#KD  
*/ Y_/w}HB   
package NetFox; uZa)N-=b2  
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import java.io.*; RV)
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import java.net.*; xwojjiV  
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public class FileSplitterFetch extends Thread { (} wMU]!_  
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String sURL; //File URL <3laNk  
long nStartPos; //File Snippet Start Position ]/7#[  
long nEndPos; //File Snippet End Position > 1=].  
int nThreadID; //Thread's ID t'[`"pp=  
boolean bDownOver = false; //Downing is over ~z'Y(qG  
boolean bStop = false; //Stop identical :{%~L4$HI  
FileAccessI fileAccessI = null; //File Access interface (
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException |LirjC4  
{ H3+P;2{  
this.sURL = sURL; 465?,EpS  
this.nStartPos = nStart; vF9fX
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this.nEndPos = nEnd; V^< Zs//7  
nThreadID = id; pYh\l.@qf  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 yM*_"z!L  
} Rbcu5.6  
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public void run() O@a7MzJ  
{ O+t'E9Fa  
while(nStartPos < nEndPos && !bStop) cToT_Mk  
{ |eqp3@Y1E  
|y4j:`@.  
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try{ as"@E>a  
URL url = new URL(sURL); @b{$s  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wZt2%+$6m  
httpConnection.setRequestProperty("User-Agent","NetFox"); \hP.Q;"MtO  
String sProperty = "bytes="+nStartPos+"-"; 2FQTu*p&B  
httpConnection.setRequestProperty("RANGE",sProperty); >aT~G!y  
Utility.log(sProperty); JZ/T:Hsh4  
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InputStream input = httpConnection.getInputStream(); iUlSRfrC$#  
//logResponseHead(httpConnection); q^6l`JJ  
8|tnhA]~  
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byte[] b = new byte[1024]; T=':$(t  
int nRead; gw<udhk  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) P>'29$1'  
{ lQpl8>  
nStartPos += fileAccessI.write(b,0,nRead); D&1(qi=x&  
//if(nThreadID == 1) ]xPy-j6C  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^GNL:D%6d  
} 36}&{A  
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,,;vG6^a  
Utility.log("Thread " + nThreadID + " is over!");  NG?g(  
bDownOver = true; T>w;M?`9K  
//nPos = fileAccessI.write (b,0,nRead); 8Yf=)  
} cC9haxW  
catch(Exception e){e.printStackTrace ();} DK1{Z;Z  
} %rO)w?  
} 0~e6\7={  
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//打印回应的头信息 Se>v|6  
public void logResponseHead(HttpURLConnection con) 
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{ _7 ^:1i~:.  
for(int i=1;;i++) <(l`zLf4p  
{ $`<-;kI  
String header=con.getHeaderFieldKey(i); !*
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if(header!=null) {}P~nP  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); w`[`
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Utility.log(header+" : "+con.getHeaderField(header)); _+}f@&"  
else oo|Nu+  
break; K+`deH_d  
} } wx(P3BHD  
} Mg&<W#$K  
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public void splitterStop() BzTzIo5  
{ @>`qfy?  
bStop = true; .M0pb^M  
} bSa]={}L(  
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} k=9k4l  
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/* t:n$9WB)  
**FileAccess.java ,fvhP $n  
*//文件访问(定位，写) s1p<F,  
package NetFox; n>xuef  
import java.io.*; iB
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public class FileAccessI implements Serializable{ VP*B<u  

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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 M,we,!B0  
RandomAccessFile oSavedFile; !\\OMAf7  
long nPos; *!yA'
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public FileAccessI() throws IOException #I#_gjJkx  
{ +1c[!;'  
this("",0); H=9{|%iS  
} l@`n4U.Gwl  
{dlG3P='`f  
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public FileAccessI(String sName,long nPos) throws IOException ;A0ZcgF  
{ !w/]V{9`X  
oSavedFile = new RandomAccessFile(sName,"rw"); =69sWcC8  
this.nPos = nPos; @XVx{t;g2  
oSavedFile.seek(nPos); czK}F/Sg`  
} 7A{Z1[7  
seb/rxb  
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public synchronized int write(byte[] b,int nStart,int nLen) eF?jNO3  
{ !8tqYY?>@\  
int n = -1; VUD9ZyPw  
try{ "
s/ws  
oSavedFile.write(b,nStart,nLen); f7Gs1{  
n = nLen; 57EL&V%j  
} X$eR RSW  
catch(IOException e) B[5<&  
{ 1*:BOoYx  
e.printStackTrace (); SVPksr  
} 7wHd*{^9N  
h~q5GhY!9  
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return n; CHDt^(oa!B  
} x
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} RY\0d
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/* xu@xP5GB^  
**SiteInfoBean.java WA5.qw  
*/ #-l+cu{  
package NetFox; =[0|qGzg  
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public class SiteInfoBean { IV%Rph>d  
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private String sSiteURL; //Site's URL 67U6`
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private String sFilePath; //Saved File's Path &&C'\,ZK5  
private String sFileName; //Saved File's Name [S0wwWU |0  
private int nSplitter; //Count of Splited Downloading File P.djR)YI  
JO~62='J  
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public SiteInfoBean() 0Kg?X  
{//nSplitter的缺省值为5 6Q_ZP#oAV  
//default value of nSplitter is 5 o'? WWJK6w  
this("","","",5); )ib$*dmUP  
}
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f,Am;:\|  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) s<5PsR  
{ ViU5l*n;  
sSiteURL= sURL; bpa
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sFilePath = sPath; 6cOlY= bn  
sFileName = sName; m14'u GC  
this.nSplitter = nSpiltter; <VhD>4f{]  
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} W*2P+H%  
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public String getSSiteURL() k h6n(B\  
{ &,* ILz  
return sSiteURL; 1JV-X G6  
} ssl.Y!  
:.(A,  
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public void setSSiteURL(String value) r-a0XNS*  
{ {9{PU&?(  
sSiteURL = value; 77'@U(  
} YR[I,j  
9xeg,
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gOMy8w4>  
public String getSFilePath() ^b 3nEcQn  
{ DXZZZ[#  
return sFilePath; L0Ajj=  
} 3Te&w9K  
1! 5VWF0  
#VsS C1  
public void setSFilePath(String value) 1/%5pb2\  
{ BE!l{  
sFilePath = value; SeLFubs_  
} T/:6Z  
H(Y1%@  
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public String getSFileName() %eGI]!vf  
{ *77Y$X##k  
return sFileName; q9c-UQB(!  
} }/Qj8l.  
]1MZ:]k  
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public void setSFileName(String value) y[GqV_~?Y  
{ t+M'05-U2  
sFileName = value; ;O~%y'  
} QY*F(S,\  
M^G9t*I  
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public int getNSplitter() <@c@`K  
{ Bq,MTzxD  
return nSplitter; WA.c.{w\  
} t ;fJ`.  
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public void setNSplitter(int nCount) =h.` ey  
{ iDdR-T|  
nSplitter = nCount; U|
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} kIRjoKf<F  
} f`8?]@y{  
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B7sBO6Z$J  
/* V6B[eV$D  
**Utility.java %g69kizoWi  
*/ 8Nx fYA  
package NetFox; ]$Q@4=fb  
@X P_~ N  
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public class Utility { /?a9g>G%N  
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public Utility()
]ZH6 .@|  
{ s+^1\  
/JIVp_-p  
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} @\+UTkl8  
=%|f-x  
//线程睡眠 ZA}!Rzo  
public static void sleep(int nSecond) i8%Z(@_`  
{ <[=[|DS l  
try{ 8C*xrg#g:  
Thread.sleep(nSecond); sX
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} 5C9 .h:c4y  
catch(Exception e) rS+ >oP}  
{ "![KQ  
e.printStackTrace (); uE>m3Y(aP  
} TCi0]Y~a  
} }%<cFi &  
-s^cy+jd  
//日志 D;OPsNQ  
public static void log(String sMsg) {mLv?"M]  
{ .(s@{=  
System.err.println(sMsg); i_nUyH%b  
} `%~f5<  
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public static void log(int sMsg) h7S; 4]  
{ 6U,:J'5gP  
System.err.println(sMsg); Q+'fTmT[,  
} nYO$ |/e  
} -6^Ee?"  
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pP%+@;  
/* g_eR&kuh  
**TestMethod.java lq?N>~PG  
*/ 9l,8:%X_  
package NetFox; .~a8\6t  
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public class TestMethod { }a
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kmt+E'^]  
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public TestMethod() S+?*l
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{ ///xx/weblogic60b2_win.exe |BO5<`&I  
try{ >b~Q%{1  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ssmJ?sl  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); qj^A  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Ifq|MZ\  
fileFetch.start(); ~se ;L  
} mA#^Pv*  
catch(Exception e){e.printStackTrace ();} jU}  
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} @@}muW>;T  
@f-rS{  
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public static void main(String[] args) z;>O5a>z  
{ xX~
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new TestMethod(); 5oOs.(m|*C  
} tq*{Hil>P`  
} >f;oY9 {m  
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