http断点续传简单实现（java)

/* QYGxr+D  
**SiteFileFetch.java Jjq%cA  
*/ jYZWf `X~  
package NetFox; 9Q1GV>j>B  
import java.io.*; _x{x#d;L3  
import java.net.*; kl9z;(6p  
0G 1o3[F  
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public class SiteFileFetch extends Thread { Shd,{Z)-Tg  
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SiteInfoBean siteInfoBean = null; //文件信息Bean X>>rvlDN  
long[] nStartPos; //开始位置 G#v7-&Yl6  
long[] nEndPos; //结束位置 S8,06/#  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 N';lc:Ah~  
long nFileLength; //文件长度 Uo ,3 lMr  
boolean bFirst = true; //是否第一次取文件 kv b-=  
boolean bStop = false; //停止标志 7d5x4^EYE  
File tmpFile; //文件下载的临时信息 B=Os?'2[  
DataOutputStream output; //输出到文件的输出流 W~FA9Jd'Z  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） i=T/}c)  
public SiteFileFetch(SiteInfoBean bean) throws IOException )frtvN7  
{ wP9C\W;  
siteInfoBean = bean; $@j7VPE  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Z}wAh|N-  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); c[$oR,2b13  
if(tmpFile.exists ()) =I1@O9}+i  
{ th)jEK;Z  
bFirst = false; 2<|5zF  
read_nPos(); ~k3r$e@  
} 0l6%[U?o  
else o<4LL7$A!  
{ DI7trR`  
nStartPos = new long[bean.getNSplitter()]; f@mM&e=f  
nEndPos = new long[bean.getNSplitter()]; 3a0C<hW
 
} :xV&%Qa1  
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} i469<^A  
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public void run() 580t@?  
{ 
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//获得文件长度 Du/s  
//分割文件 e.T5F`Du  
//实例FileSplitterFetch p,+~dn;=  
//启动FileSplitterFetch线程 okYsj
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//等待子线程返回 (Gc5lMiX3  
try{ tL~|/C)d R  
if(bFirst) CeQcnJU  
{ TCEbz8ql  
nFileLength = getFileSize(); F ;D_zo?  
if(nFileLength == -1) bQ)r8[o!  
{ qH ~usgqB7  
System.err.println("File Length is not known!"); $lqV(s  
} U:>O6"  
else if(nFileLength == -2) 0kkiS3T  
{ EW`3h9v~  
System.err.println("File is not access!"); }fhVn;~}8  
} s)V
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else 09"~<W8  
{ n)0{mDf%  
for(int i=0;i<nStartPos.length;i++) "*
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{ Gc'HF"w  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); x83XJFPWL  
} 5
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for(int i=0;i<nEndPos.length-1;i++) ofSOy1  
{ T \AuL  
nEndPos = nStartPos[i+1]; >#ou8}0  
} x6,RW],FGR  
nEndPos[nEndPos.length-1] = nFileLength; 2rH6ap  
} nYe}d!  
} >5j/4Ly  
i||YD-hkK  
T;%SB&  
//启动子线程 fG{oi(T  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; RS1oPY  
for(int i=0;i<nStartPos.length;i++) J0oR]eT}  
{ +2g3%c0}  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), iO@wqbg$6  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), u>eu47"n!  
nStartPos,nEndPos,i); |WX4L7yrhK  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); pxF!<nN1,  
fileSplitterFetch.start(); ,i|f8pZ  
} G pd:k  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 3)ip@29F  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); I,[EL{fz  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", e'6?iLpy  
nEndPos = " + nFileLength); !9 F+uc5  
// fileSplitterFetch[nPos.length-1].start(); "&%Hb's  
3:gk:j#  
6i
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//等待子线程结束 -FI1$  
//int count = 0; J]UHq$B  
//是否结束while循环 ,?qS#B+>  
boolean breakWhile = false; Ojs\2('u  
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while(!bStop) :wZZ 1qa  
{ DH^^$)  
write_nPos(); fCfY.vd5  
Utility.sleep(500); ~iWSc8-  
breakWhile = true; Qs:r@"hE  
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for(int i=0;i<nStartPos.length;i++) 'Aj>+H<B  
{ wjOAgOC  
if(!fileSplitterFetch.bDownOver) ISew]R2  
{ %SCu29km  
breakWhile = false; Oy$BR <\  
break; \Rqh|T<D  
} 3
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} umZ g}|C_  
if(breakWhile) %%cSvPcz  
break; )-
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//count++; a {$k<@Ww  
//if(count>4) ec4%Wk2  
// siteStop(); [=ak>>8  
} )]?egw5l  
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System.err.println("文件下载结束！"); 3r:)\E+Q_  
} 3k*:B~1  
catch(Exception e){e.printStackTrace ();} xT?}wF  
} ca3BJWY}J  
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//获得文件长度 P,;b'-5C  
public long getFileSize() Jv^cOc  
{ b}&7~4zw  
int nFileLength = -1; ]RXtC*  
try{ |8qK%n f}  
URL url = new URL(siteInfoBean.getSSiteURL()); d?&!y]RS#  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); @S"pJeP/f  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'Rkvsch  
*- IlF]  
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int responseCode=httpConnection.getResponseCode();
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if(responseCode>=400) 56=K@$L {F  
{ iPY vePQ  
processErrorCode(responseCode); kV:FJx0xP  
return -2; //-2 represent access is error g\\1C2jG  
} ZA_zKJ[[7  
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String sHeader; bg1"v a#2  
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for(int i=1;;i++) 2 ]DCF  
{ uVq5fT`B  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); qaMZfA  
//Utility.log(in.readLine()); 3$$5Mk(&  
sHeader=httpConnection.getHeaderFieldKey(i); >^H'ZYzw  
if(sHeader!=null) PJK]t7vp  
{ ?zhI=1ED%  
if(sHeader.equals("Content-Length")) 0/SC  
{ e>,9]{N+$  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); +Y5(
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break; Iu-'o  
} :,S8T%d  
} Z[})40[M  
else z{`6#  
break; e+F}9HR7  
}
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} N /sEec  
catch(IOException e){e.printStackTrace ();} rb *C-NutE  
catch(Exception e){e.printStackTrace ();} Z{a{HX[Jx  
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Utility.log(nFileLength); "M9TB. O  
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return nFileLength; Th7wP:iDP  
} nW$A^  
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//保存下载信息（文件指针位置） d7W%zg\T
 
private void write_nPos() IOsXP
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{ I;kf #nvao  
try{ X
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output = new DataOutputStream(new FileOutputStream(tmpFile)); 9E
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output.writeInt(nStartPos.length); _&; ZmNNhc  
for(int i=0;i<nStartPos.length;i++) '?{0z!!  
{ :b<-[8d&  
// output.writeLong(nPos); Exep+x-  
output.writeLong(fileSplitterFetch.nStartPos); x1 ;rb8  
output.writeLong(fileSplitterFetch.nEndPos); wUru1_zjO  
} [<D+pqh  
output.close(); FasI'Ulk  
} K,x$c %  
catch(IOException e){e.printStackTrace ();} d3EjI6R*z  
catch(Exception e){e.printStackTrace ();} CDQJ bvx  
} 'v'` F*6  
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//读取保存的下载信息（文件指针位置） ?)!SmN/  
private void read_nPos() !: m`9o8  
{ H/^~<U#p  
try{ 5h|'DOx|o  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ]~?S~l%  
int nCount = input.readInt(); D-Bv(/Pz]$  
nStartPos = new long[nCount]; 'fS?xDs-v  
nEndPos = new long[nCount]; }7iUagN  
for(int i=0;i<nStartPos.length;i++) |f"-|6  
{ <8iYL`3  
nStartPos = input.readLong(); W:`5nj]H9  
nEndPos = input.readLong(); Z -pyFK\  
} >:.w7LQy/  
input.close(); =RQ )$ %  
} lP}od  
catch(IOException e){e.printStackTrace ();} {udrT"h  
catch(Exception e){e.printStackTrace ();} u
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} @b]VCv0*f%  
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private void processErrorCode(int nErrorCode) NV&;e[z  
{ btUq  
System.err.println("Error Code : " + nErrorCode); I_:t}3s  
} Bp&6x;MJf  
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UE"7

  
//停止文件下载 ktN%!Mh\  
public void siteStop() $=\d1%_R|  
{ P\.WXe#j  
bStop = true; A)OdQFet(  
for(int i=0;i<nStartPos.length;i++) S
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fileSplitterFetch.splitterStop(); l &}piC  
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} s;s0}Td_1  
} =\M)6"}y}  
//负责部分文件的抓取 y^9bfMA  
**FileSplitterFetch.java :eSc;  
*/ L?C\Q^0"`G  
package NetFox; %=y;L:S\p  
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import java.io.*; w(/7Jt$  
import java.net.*; N
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public class FileSplitterFetch extends Thread { hMv2"V-X  
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String sURL; //File URL ebzzzmwo  
long nStartPos; //File Snippet Start Position )W#T2Z>N1  
long nEndPos; //File Snippet End Position gglf\)E;}E  
int nThreadID; //Thread's ID z23#G>I&  
boolean bDownOver = false; //Downing is over x9h?e`  
boolean bStop = false; //Stop identical Is ot4HLM  
FileAccessI fileAccessI = null; //File Access interface 2H6:np|O  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException { E^U6@  
{ Mw+v"l&mU  
this.sURL = sURL; sp^Wo7&g  
this.nStartPos = nStart;
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this.nEndPos = nEnd; grc:Y  
nThreadID = id; iM"asEU  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 w#sq'vo4%  
} @$oZ|ZkZ  
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public void run() wE?CvL  
{ =x1Wii$`  
while(nStartPos < nEndPos && !bStop) Gy9 $Wj  
{ 5} G:D  
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try{ ~}K{e  
URL url = new URL(sURL); i*'Z3Z)  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); PYu$1o9+N  
httpConnection.setRequestProperty("User-Agent","NetFox"); *Z; r B  
String sProperty = "bytes="+nStartPos+"-"; h D.)M  
httpConnection.setRequestProperty("RANGE",sProperty); XC2FF&B&  
Utility.log(sProperty); "T7>)fbu  

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InputStream input = httpConnection.getInputStream(); TtZ}
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//logResponseHead(httpConnection); O>%$q8x@i  
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byte[] b = new byte[1024]; Y.NE^Vn0  
int nRead; Q ?^4
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) e}e6r3faz  
{ NV6G.x  
nStartPos += fileAccessI.write(b,0,nRead); t!:)L+$3  
//if(nThreadID == 1) M$H`^P
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); YQ7@D]#  
} xp^ 7#`MJ?  
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Utility.log("Thread " + nThreadID + " is over!"); `;cz;"  
bDownOver = true; d8o ewkiR  
//nPos = fileAccessI.write (b,0,nRead); _C$X04bU3V  
} 1O0X-C,wo$  
catch(Exception e){e.printStackTrace ();} ]Jn2Ra"j  
} G\ex^&M  
} Kp&3=e;vn{  
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//打印回应的头信息 \<V)-eB  
public void logResponseHead(HttpURLConnection con) d@ (v
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{ 1qZG`Vz  
for(int i=1;;i++) V^sc1ak1Q  
{ ve fU'  
String header=con.getHeaderFieldKey(i); H%z/v|e6  
if(header!=null) dp<$Zw8BE  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); RG1\=J$:E  
Utility.log(header+" : "+con.getHeaderField(header)); " #v%36U  
else RG}}Oh="v  
break; 8wmQ4){  
} :c:V%0Yji  
} w & P&7  
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public void splitterStop() 8R?I`M_b  
{ r6 }_H?j  
bStop = true; :)4*^a/lC  
} U\bC0q   
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} 1tGgDbJU  
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/* ;;Tq$#vd  
**FileAccess.java C:j]43`  
*//文件访问(定位，写) |}Ph"g2D,  
package NetFox; E1(1E?}!  
import java.io.*; !*vBW/  
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public class FileAccessI implements Serializable{ doLNz4W  
[r9d<Zi}{  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 |';7v)CIG  
RandomAccessFile oSavedFile; '[0YIn  
long nPos; u"FjwF?  
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public FileAccessI() throws IOException jQ$BPEG&X  
{ tX?J
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this("",0); CDCC1BG"  
} 9@y3IiZ"}  
P {H{UKs#  
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public FileAccessI(String sName,long nPos) throws IOException Ac\W\=QvB  
{ c0[k T  
oSavedFile = new RandomAccessFile(sName,"rw"); /gw Cwyo  
this.nPos = nPos; 'n4u-pM(nB  
oSavedFile.seek(nPos); 1X&B:_  
} F1c&0*_A  
. #U}q 7X  
'{VM>
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public synchronized int write(byte[] b,int nStart,int nLen) TB#Nk5  
{ 3dm'xetM  
int n = -1; KY+]RxX  
try{ 7zGMkl  
oSavedFile.write(b,nStart,nLen); j-32S!  
n = nLen; hk;bk?:m  
} j@v-|  
catch(IOException e) qd(hQsfqYU  
{ RIjM(P  
e.printStackTrace (); m&Sp1=*Ejy  
} xa#gWIP*  
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return n; -3vh!JMN  
} d?7BxYa
a  
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} bn-=fb(  
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/* <25ccE9^c  
**SiteInfoBean.java 6"
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*/ 6x4_b  
package NetFox; !Uy>eji}  
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public class SiteInfoBean { ZNL5({lv  
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private String sSiteURL; //Site's URL {US>)I  
private String sFilePath; //Saved File's Path fIkT"?  
private String sFileName; //Saved File's Name VDn:SGj5  
private int nSplitter; //Count of Splited Downloading File 5/(sjMB  
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public SiteInfoBean() x4 hO$3o  
{//nSplitter的缺省值为5 
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//default value of nSplitter is 5 @_Sp3nWdu  
this("","","",5); {AgBwBCE  
} s41adw>  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) {aIZFe}B  
{ "XB4yExy  
sSiteURL= sURL; nx$bM(.  
sFilePath = sPath; Z@oKz:U  
sFileName = sName; e5L1er;6  
this.nSplitter = nSpiltter; Bac|;+L~L  
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} %omu
 
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public String getSSiteURL() Q@Dkl F  
{ `
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return sSiteURL; N'a?wBBR  
} vX 1W@s  
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public void setSSiteURL(String value) q;No"_aAd  
{ IywiCMjH  
sSiteURL = value; ydyG}XI
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} :mn(0 R~  
jm+blB^%K  
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public String getSFilePath() *?p ^6vO  
{ wA1Ey:q  
return sFilePath; ^vG=|X|)c  
} H7}g!n?  
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6N?#b66  
public void setSFilePath(String value) [\a:4vDAbi  
{ "R8.P/ 3  
sFilePath = value; V07VwVD  
} U Q)!|@&  
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J ZA*{n2  
public String getSFileName() [.ey_}X8  
{ ]~'9  
return sFileName; C_-%*]*,j  
} m[W/j/$A+x  
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public void setSFileName(String value) WqR7uiCi  
{ O%52V|m}{  
sFileName = value; "~_$T@^k>  
} *!i,?vn  
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public int getNSplitter() O/(3 87=U  
{ lQh~Q<[ge  
return nSplitter; |^?`Q.|c$  
} J0Jr BXCh  
R08&cd#$  
.l7j8}  
public void setNSplitter(int nCount) hI*`>9l  
{ -Sx0qi'%  
nSplitter = nCount; re]%f"v:5  
} pa>p%  
} :,jPNuOA  
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s%5Uj}  
/* WUzSlZq  
**Utility.java (Z5q&#f  
*/ 93 [rL+l.Y  
package NetFox; $|rCrak;  
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public class Utility { AbL5 !'  
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public Utility() "&@gX_%  
{ "tfn?n0  
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}*0,>w>  
} G}182"#4  
m"5{D*|  
//线程睡眠 )>ug{M%g  
public static void sleep(int nSecond) hT.4t,wa8  
{ Tnf&pu#5  
try{ Y,3z-Pa=@  
Thread.sleep(nSecond); 9 aY'0w
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} H~~7~1"x  
catch(Exception e) nUiS<D2  
{  -PcS(  
e.printStackTrace (); c$@`P  
} !>CE(;E>z  
} lq;  
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//日志 $5ZR[\$  
public static void log(String sMsg) f1)HHUB  
{ OD{5m(JwL  
System.err.println(sMsg); 1,m\Q_  
} oxUE79  
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public static void log(int sMsg) O]c=Yyl  
{ );0<Odw%.  
System.err.println(sMsg); Gtj(  
} T+`xr0  
} JQ~y- lt  
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!S
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/* 8:Z@lp^  
**TestMethod.java lc\>DH\n6  
*/ szf"|k!  
package NetFox; t#fs:A7P?}  
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public class TestMethod { SZCF3m&pz  
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public TestMethod() aK8bKlZe  
{ ///xx/weblogic60b2_win.exe 3!i.Fmo  
try{ J xA^DH  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); *>H
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//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Dj-\))L  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 4^d+l.F  
fileFetch.start(); <C7M";54-  
} kvMk:.  
catch(Exception e){e.printStackTrace ();} J!21`M-Ue  
!^c:'I>~  
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} '5|Q<5!o  
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public static void main(String[] args) V_)5Af3wY  
{ +-Z"H)  
new TestMethod(); }-R
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} y3 ({(URU  
} M/::`yJQu  
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