http断点续传简单实现（java)

/* ld|5TN1  
**SiteFileFetch.java (^
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*/ ~drS} V  
package NetFox;
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import java.io.*; jH5 k  
import java.net.*; }l(&}#dY  
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public class SiteFileFetch extends Thread { EnKR%Ctw  
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SiteInfoBean siteInfoBean = null; //文件信息Bean )0.kv2o.  
long[] nStartPos; //开始位置 [64:4/<}  
long[] nEndPos; //结束位置 Sxt"B  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 7{e 4c  
long nFileLength; //文件长度 r_)' Ps  
boolean bFirst = true; //是否第一次取文件 P%V'4pc  
boolean bStop = false; //停止标志 GfxZ'VIn  
File tmpFile; //文件下载的临时信息 fa jGZyd0:  
DataOutputStream output; //输出到文件的输出流 :KSV4>X[%a  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Z, zWuE3  
public SiteFileFetch(SiteInfoBean bean) throws IOException
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{ QUwd [  
siteInfoBean = bean; y|C(X  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); qTRsZz@  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ,8S/t+H  
if(tmpFile.exists ()) -/wtI   
{ tVYF{3BhA  
bFirst = false; n$MO4s8)  
read_nPos(); YFLZ%(  
} XO>KZV7)  
else 6y-@iJ*ld;  
{ 4M=]wR;  
nStartPos = new long[bean.getNSplitter()]; rT=rrvV3g  
nEndPos = new long[bean.getNSplitter()]; ?qv
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} m4[;(1  
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} uanhr)Ys  
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public void run() J|W<;  
{ 1jmjg~W  
//获得文件长度 JK7G/]j+Ez  
//分割文件 EKYY6S2  
//实例FileSplitterFetch P>y@kPi  
//启动FileSplitterFetch线程 Q
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//等待子线程返回 <O(4
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try{ |%BOZT  
if(bFirst) N~nziY*C,*  
{ $g^@AdE%  
nFileLength = getFileSize(); ]}>2D,;  
if(nFileLength == -1) Z\(q@3C  
{ z 4e7PW|  
System.err.println("File Length is not known!"); AmUr.ofu  
} rX U  
else if(nFileLength == -2) [$ubNk;!z  
{ lB8-Z ow  
System.err.println("File is not access!"); :tc@2/>!O  
} I }a`0Y&{  
else ")1:F>  
{ DHg:8%3x  
for(int i=0;i<nStartPos.length;i++) y B81f  
{ *[Imn\hu  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); H9Gh>u]}  
} R)?*N@.s  
for(int i=0;i<nEndPos.length-1;i++) 0gu_yg!R  
{ [CTnXb  
nEndPos = nStartPos[i+1]; /m!BY}4W  
} B5,N7z34F  
nEndPos[nEndPos.length-1] = nFileLength; <X#C)-.  
} ^7`BP%6  
} OW&!at  
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//启动子线程 WSPI|#Xr%  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length];
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for(int i=0;i<nStartPos.length;i++) n.}ZkG0`  
{ xf'V{9*  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), "-E\[@/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), "6("9"  
nStartPos,nEndPos,i); `{
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); nd`1m[7MNu  
fileSplitterFetch.start(); FBG4pb9=~  
} B5`EoZ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), av(6wht8  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 3RUy,s  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", fQ7V/x!  
nEndPos = " + nFileLength); +Z,;,5'5G  
// fileSplitterFetch[nPos.length-1].start(); 2/U.|*mH  
#QZe,"C9`  
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//等待子线程结束 9v#CE!  
//int count = 0; k<z)WNBf  
//是否结束while循环 xPdG*OcX!  
boolean breakWhile = false; \wmN  
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while(!bStop) XjBW9a  
{ 05|=`eJ  
write_nPos(); )|ccX  
Utility.sleep(500); MnmVl"(/  
breakWhile = true; hy9\57_#  
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for(int i=0;i<nStartPos.length;i++) EX*HiZU>  
{ 4a&RYx  
if(!fileSplitterFetch.bDownOver) 2bz2KB5>  
{ //B&k`u  
breakWhile = false; ;2G*wR  
break; &.3"Uo\#  
} &*o=I|pQ  
} }ZYd4h|g\z  
if(breakWhile) 3s*mbk[J  
break; `4r 3l S  
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//count++; ]IaMp78
8  
//if(count>4) ~"gA,e-)  
// siteStop(); "2!&5s,1p  
} C-xr"]#]  
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System.err.println("文件下载结束！"); n>z9K')  
} 5; C|  
catch(Exception e){e.printStackTrace ();} VCYwzB  
} ,};&tR  
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//获得文件长度 XoK:N$\}t  
public long getFileSize() $L`d&$Vh  
{ 'JtBZFq  
int nFileLength = -1; #Bze
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try{ UhF-K#Z9  
URL url = new URL(siteInfoBean.getSSiteURL()); 5{TsiZh4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3l]lwV  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'B$
yo]  
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int responseCode=httpConnection.getResponseCode(); a"1t-x  
if(responseCode>=400) ?Rb9|`6  
{ yNBQGSH  
processErrorCode(responseCode); S E<FL/x1#  
return -2; //-2 represent access is error ]Ee?6]bN  
}  y`iBFC;_  
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String sHeader; _{ue8kGt  
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for(int i=1;;i++) \0gis#  
{ B^=-Z8  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); t3WiomNCc  
//Utility.log(in.readLine()); .N;=\C
*  
sHeader=httpConnection.getHeaderFieldKey(i); ;._ l0Jw  
if(sHeader!=null) cdH>n)  
{ E,Z$pKL?  
if(sHeader.equals("Content-Length")) Xfc-UP|}  
{ q_lKKzA  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Q>qUk@  
break; ux-/>enc  
} umBICC]CU  
} W ~<^L\Lu  
else u~N?NW Q  
break; iO$8:mxm0?  
} Y;eZ9|Ht9  
} [|wZ77\  
catch(IOException e){e.printStackTrace ();} Z{.8^u1I  
catch(Exception e){e.printStackTrace ();} NSMyliM1Y  
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Utility.log(nFileLength); W-f=]eWg  
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return nFileLength; *tFHM &a  
} C.:<-xo  
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//保存下载信息（文件指针位置） ~%F9%=  
private void write_nPos() 8$cLG*=h4  
{ CZe ]kXNv  
try{ )CYGQMK  
output = new DataOutputStream(new FileOutputStream(tmpFile)); w_c"@CjkE  
output.writeInt(nStartPos.length); <V'@ks%  
for(int i=0;i<nStartPos.length;i++) L- iy  
{ qx(xvU9  
// output.writeLong(nPos); %QH$ipM  
output.writeLong(fileSplitterFetch.nStartPos); h f)?1z4  
output.writeLong(fileSplitterFetch.nEndPos); 3Aip}<1  
} *"2+B&Y  
output.close(); iozt&~o  
} X #dmo/L8  
catch(IOException e){e.printStackTrace ();} :k]1Lm|
|  
catch(Exception e){e.printStackTrace ();} h^45,E C  
} g'f@H-KCD  
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//读取保存的下载信息（文件指针位置） Z#jZRNU%ox  
private void read_nPos() 68|E9^`l  
{ S\EyCi+  
try{
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); PQt")[
 
int nCount = input.readInt(); w(Ovr`o?9t  
nStartPos = new long[nCount]; SGRp3,1\4%  
nEndPos = new long[nCount]; Jrf=@m\dk  
for(int i=0;i<nStartPos.length;i++) KkyVSoD\  
{ }Bh8=F3O Q  
nStartPos = input.readLong(); YaqR[F  
nEndPos = input.readLong(); k}CVQ@nd  
} @IKYh{j4  
input.close(); V-P#1Kkh  
} ssA`I<p#  
catch(IOException e){e.printStackTrace ();} ,,.QfUj/&  
catch(Exception e){e.printStackTrace ();} FXCMR\
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} ZoqZap6e  
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private void processErrorCode(int nErrorCode) _ye |Y  
{ \\ij(>CI  
System.err.println("Error Code : " + nErrorCode); :G=fl)!fE  
} Ny7S  
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//停止文件下载 c]<5zyl"j1  
public void siteStop() 0o4XUW   
{ k'Hs}zeNn  
bStop = true; s)t@ol  
for(int i=0;i<nStartPos.length;i++) M?49TOQA  
fileSplitterFetch.splitterStop(); ;d$rdFA_  
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} bj^5yX;2  
} ]cvwIc">  
//负责部分文件的抓取 0auYG><=  
**FileSplitterFetch.java aK~8B_5k8  
*/ 8`{:MkXP  
package NetFox; aKDKmHd  
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import java.io.*; e"cXun4nS=  
import java.net.*; R^fPIv`q  
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public class FileSplitterFetch extends Thread { FxY}m  
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String sURL; //File URL E=Bf1/c\  
long nStartPos; //File Snippet Start Position Y-z(zS^1  
long nEndPos; //File Snippet End Position \l0[rcEf  
int nThreadID; //Thread's ID =%O6:YM   
boolean bDownOver = false; //Downing is over fbvL7* (  
boolean bStop = false; //Stop identical /s?`&1v|r  
FileAccessI fileAccessI = null; //File Access interface n&/ `  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException
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{ W*:.Gxv]  
this.sURL = sURL; 6_;icpN]  
this.nStartPos = nStart; MchA{p&Ol  
this.nEndPos = nEnd; hZ,_6mNg  
nThreadID = id; I 34>X`[o  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 a-tmq]]E  
} @1j   
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public void run() 2tO,dx  
{ Rp7mh]kZ  
while(nStartPos < nEndPos && !bStop) DCa^ u'f  
{ 9=tIz  
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try{ `}\ "Aw c  
URL url = new URL(sURL); 8Fh)eha9f  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); U/M>?G~  
httpConnection.setRequestProperty("User-Agent","NetFox"); >Tx?%nQ  
String sProperty = "bytes="+nStartPos+"-"; TX/Xt7#R:  
httpConnection.setRequestProperty("RANGE",sProperty); |e&\<LwsP  
Utility.log(sProperty); 'Is kWgc  
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InputStream input = httpConnection.getInputStream(); .{^5X)  
//logResponseHead(httpConnection); kZ:ZtE  
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byte[] b = new byte[1024]; B[Scr5|  
int nRead; P+sW[:  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 3?yg\  
{ i]4I [!  
nStartPos += fileAccessI.write(b,0,nRead); n@i HFBb  
//if(nThreadID == 1) WwFm*4{[o  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); r6qj7}\  
}
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Utility.log("Thread " + nThreadID + " is over!"); JbbzV>  
bDownOver = true; "sCRdx]_  
//nPos = fileAccessI.write (b,0,nRead); xo&_bMO  
} ^ @5QP$.  
catch(Exception e){e.printStackTrace ();} V!=,0zy~Z  
} 3d]S!=4H"  
} J8(lIk:e  
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//打印回应的头信息 NI]N4[8(  
public void logResponseHead(HttpURLConnection con) 6gE7e|+  
{ 'H!Uh]!  
for(int i=1;;i++) R n[cW5Y<  
{ am'7uy!ka~  
String header=con.getHeaderFieldKey(i); kzLsoZ!I  
if(header!=null) X_h}J=33Q  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); cT,sh~
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Utility.log(header+" : "+con.getHeaderField(header)); 8<.Oq4ku  
else Il'fL'3  
break; t*u:hex  
} eym4=k ~  
} /3T1U  
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public void splitterStop() niyV8
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{ CTa57R  
bStop = true; oc`H}Wvn  
} F4
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3 0H?KAV  
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} da(<K}  
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/* cwg"c4V  
**FileAccess.java z:*|a+cy  
*//文件访问(定位，写) D,feF9  
package NetFox; ,qxu|9L  
import java.io.*; bn5 Su
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public class FileAccessI implements Serializable{ i/4>2y9/F4  
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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 '=pU^
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RandomAccessFile oSavedFile; y)@wjH{6  
long nPos; K0>zxqY  
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public FileAccessI() throws IOException (<9u-HF#  
{ 8A#;WG  
this("",0); mzgfFNm^G)  
} 77Dn97l)&  
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public FileAccessI(String sName,long nPos) throws IOException e^voW"?%  
{ <5051UEu  
oSavedFile = new RandomAccessFile(sName,"rw"); 2+XAX:YD  
this.nPos = nPos; ;V!D:5U  
oSavedFile.seek(nPos); @VEb{ w[H  
} |6-nbj  
9*M,R,y  
@yYkti;4-  
public synchronized int write(byte[] b,int nStart,int nLen) zb3tIRH  
{ =s6 opL)  
int n = -1; 59u}W 0  
try{ l/5 hp.  
oSavedFile.write(b,nStart,nLen); [/r(__.  
n = nLen; `a/`,N  
} ^2rN>k,?  
catch(IOException e) yG{TH0tq  
{ E1 2uZ$X  
e.printStackTrace (); FSO).=#  
} F== p<lrs  
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return n; !N^@4*  
} m&3xJuKih  
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} a<e[e>  

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/* -9?]IIVb  
**SiteInfoBean.java ;_=&-mz  
*/ omx=  
package NetFox; Mtx4'WZ  
;'1d1\wiDQ  
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public class SiteInfoBean { [}m[)L\  
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private String sSiteURL; //Site's URL *T1_;4i  
private String sFilePath; //Saved File's Path {!`6zBsP  
private String sFileName; //Saved File's Name #vlgwA  
private int nSplitter; //Count of Splited Downloading File lOp`m8_=  
8@R|Km5h  
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public SiteInfoBean() 7tp36TE  
{//nSplitter的缺省值为5 l[J8!u2Xp  
//default value of nSplitter is 5 P+}h$_x  
this("","","",5); j~MI<I+l[  
} WIGi51yC.x  
ALHIGJW:6$  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ,esmV-  
{ ar,7S&sH  
sSiteURL= sURL; \U_@S.  
sFilePath = sPath; LP=)~K
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sFileName = sName; n6v6K1  
this.nSplitter = nSpiltter; W,u:gzmhw  
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} %so]L+r2!  
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public String getSSiteURL() j<$2hiI/?&  
{ l,).p  
return sSiteURL; HaYo!.(Fv  
} ;*J  
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public void setSSiteURL(String value) ,,r>,Xq6  
{ 7:@'B|  
sSiteURL = value; AXB7oV,xt  
} :6dxtl/{b:  
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public String getSFilePath() ,x
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{ ^zr`;cJ+c  
return sFilePath; Y/oHu@ _  
} +C)~bb*  
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public void setSFilePath(String value) lquLT6]  
{ VU#7%ufu&  
sFilePath = value; jiGTA:v
 
} pfPz8L.7  
#&4=VGx{ #  
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public String getSFileName() Gm`8q}<I  
{ .)3<Q}>  
return sFileName; k3|Z7eW}[  
} ^z\cyT%7t  
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public void setSFileName(String value) \7_y%HR  
{ {RPI]DcO/  
sFileName = value; zm# ?W  
} iow"n$/  
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public int getNSplitter() 3' 'me  
{ IGgL7^MF  
return nSplitter; ,: ^u-b|  
} ~"bVL[  
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public void setNSplitter(int nCount) _v:SP LU  
{ +,l-Nz  
nSplitter = nCount; 'fW-Y!k%  
} L50n8s  
} wM{s|Ay  
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tX[WH\(xI  
/* bd`P0f?  
**Utility.java 9JwPSAo;  
*/ T4F/w|Q  
package NetFox; SfR%s8c`  
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public class Utility { {G-kNU  
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public Utility() zeRyL3fnmb  
{ m+9#5a-  
;a
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} hGrdtsH?  
DNi+"[~&P  
//线程睡眠 kT=8e;K  
public static void sleep(int nSecond) lxi<F  
{ [hsds\  
try{ 8k79&|  
Thread.sleep(nSecond); P~dcW  
} =u;MCQ[  
catch(Exception e) z%kULTL  
{ !9x}  
e.printStackTrace (); R-Sym8c  
} -qoH,4w  
} 8Y?;x}  
rlD8D|ZG  
//日志 V8(-  
public static void log(String sMsg) pot~<d`:K"  
{ ce(#2o&`  
System.err.println(sMsg); Ca\6v
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} N21smC}  
w =KPT''!  
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public static void log(int sMsg) Ho%CDz z  
{ +[P{&\d4}  
System.err.println(sMsg); Zc2PepIg  
} 0YHFvy)  
} <GsuZ  
n`KY9[0U=  
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/* j!ch5A  
**TestMethod.java nDW9NQ  
*/ W>LR\]Ti@  
package NetFox; D,6:EV"sa  
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public class TestMethod { &wX]_:?  
cnLro  

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public TestMethod() KTv$  
{ ///xx/weblogic60b2_win.exe -YE^zzh  
try{ ;Qq\DFe.w  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ~5g~;f[4  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); `{Ul!  
SiteFileFetch fileFetch = new SiteFileFetch(bean); [ 3HfQ  
fileFetch.start(); ctUp=po  
} YzWz|  
catch(Exception e){e.printStackTrace ();} #Dac~>a'  
*h|U,T7ew
 
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} /
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public static void main(String[] args) xkn;,`t^lJ  
{ v2?ZQeHr_(  
new TestMethod(); 5)E @F9N  
} S[N5 i
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} T;uX4,|(  
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