http断点续传简单实现（java)

/* z$lF)r:Bc  
**SiteFileFetch.java :t$aN|>y  
*/ n^(A=G  
package NetFox; km5~Gc}  
import java.io.*; qNgd33u1  
import java.net.*; is;XmF*5=  
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public class SiteFileFetch extends Thread { j`*N,*ha  
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SiteInfoBean siteInfoBean = null; //文件信息Bean V3N0Og3  
long[] nStartPos; //开始位置 P,pnga3Wu  
long[] nEndPos; //结束位置 H!IshZfktn  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 2C^B_FUg|]  
long nFileLength; //文件长度 LE^G&<!  
boolean bFirst = true; //是否第一次取文件 [s1pM1x  
boolean bStop = false; //停止标志 0'Z\O   
File tmpFile; //文件下载的临时信息 SkNre$>t{  
DataOutputStream output; //输出到文件的输出流 j=+"Qz/hr_  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 5`[n8mU  
public SiteFileFetch(SiteInfoBean bean) throws IOException ^)yTBn,  
{ G* b2,9&F  
siteInfoBean = bean; yBed kj  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); we7c`1E  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); .aOnGp  
if(tmpFile.exists ()) {i~8 :  
{ )vB2!H/  
bFirst = false; y %8op:'  
read_nPos(); vEe NW  
} 9.O8/0w7LV  
else k,Qskd-N]  
{ :c[n\)U[aa  
nStartPos = new long[bean.getNSplitter()]; ks;%*d  
nEndPos = new long[bean.getNSplitter()]; `\Ku]6J]5  
} .ae O}^  
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} `\|ssC8u  
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public void run() 7Du1RuxP  
{ nxm$}
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//获得文件长度 ,.IEDF<&  
//分割文件 (WlIwKP  
//实例FileSplitterFetch qa >Ay|92e  
//启动FileSplitterFetch线程 [&S}dQ"  
//等待子线程返回 Oeya%C5'  
try{ \a^,sV  
if(bFirst) th5g\h%j*  
{ 
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nFileLength = getFileSize(); 8G%yB}pa  
if(nFileLength == -1) )x,8D ~p'  
{ O{z}8&oR:  
System.err.println("File Length is not known!"); n";02?@F  
} ,"}Rg1\4t  
else if(nFileLength == -2) *~$~yM/~3U  
{ { >{B`e`$  
System.err.println("File is not access!"); _A_ A$N~9  
} p\vMc\  
else gieJ}Bv  
{ ]1-z!B4K  
for(int i=0;i<nStartPos.length;i++) =TvzS%U  
{ tCF&OOI4`  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ~=r^3nZR/J  
} donw(_=  
for(int i=0;i<nEndPos.length-1;i++) nx":"LFI  
{ 6qvp*35Cx  
nEndPos = nStartPos[i+1]; E9!N>0  
} s=I'e/"7  
nEndPos[nEndPos.length-1] = nFileLength; \g)Xt?w0Wo  
} bBxw#_3A?E  
} G`=r^$.3WB  
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//启动子线程 1[nG}  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]Al;l*
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for(int i=0;i<nStartPos.length;i++) k5d\w@G"~  
{ J<n+\F-s  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ;+"f  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), LS>G4 ]  
nStartPos,nEndPos,i); =8G&3 R  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); BG2)v.CU  
fileSplitterFetch.start(); vW,snxK6y&  
} %5Kq^]q;Y  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), q(^Q3  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ]Z<_ "F  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", c/W=$
3  
nEndPos = " + nFileLength); RWq{Ff}Hk  
// fileSplitterFetch[nPos.length-1].start(); /G{_7cb  
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//等待子线程结束 U4?(A@z9^  
//int count = 0; 4_M>OD/"  
//是否结束while循环 /BKe+]dS*  
boolean breakWhile = false; 7J$b$P0}  
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while(!bStop) =(AtfW^H  
{ n_K~vD  
write_nPos(); V)o,1  
Utility.sleep(500);   \J^  
breakWhile = true; 2+8#H.  
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for(int i=0;i<nStartPos.length;i++)
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{ l":c  
if(!fileSplitterFetch.bDownOver) )bOBQbj  
{ EEy$w1ec  
breakWhile = false; d4[(8} x$/  
break; 01a-{&   
} u8
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} !,$i6gm  
if(breakWhile) 1nj(hg  
break; qf'm=efRyu  
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-!qu"A:  
//count++; pz^<\  
//if(count>4) .o{0+fC#  
// siteStop(); -XoPia2  
} pI`?(5iK6|  
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System.err.println("文件下载结束！"); PrF}a<:n:  
} 2 mjV
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catch(Exception e){e.printStackTrace ();} lB8il2&  
} 5,"l0nrk  
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//获得文件长度 `\>.
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public long getFileSize() Lr;(xw\[
'  
{ z~6y+  
int nFileLength = -1; Lju7,/UD  
try{ UQCo}vM  
URL url = new URL(siteInfoBean.getSSiteURL()); Y+%sBqo@  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); < O*6T%;  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;d.K_P  
.uo.N  
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int responseCode=httpConnection.getResponseCode(); `WEZ"5n  
if(responseCode>=400) *TW=/+j  
{ }Y(]6$uS  
processErrorCode(responseCode); $V>98M>j  
return -2; //-2 represent access is error !H][LXB~H  
} ^^`Jcd/  
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String sHeader; }]1BO  
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for(int i=1;;i++) l2%bF8]z  
{ f},oj4P\  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ^he=)rBb?  
//Utility.log(in.readLine()); Yx'res4e  
sHeader=httpConnection.getHeaderFieldKey(i); ?C0l~:j7D  
if(sHeader!=null) <3PL@orO  
{ u),Qa=Wp  
if(sHeader.equals("Content-Length")) PQW(EeQ  
{ Gnm4gF!BI  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); - "*r  
break; 23(=Xp3;>  
} 73A)lU.  
} 31+;]W=  
else {Ee>n^1  
break; v;#=e$%}MO  
} W)j|rz.  
} ?eV(1Fr@  
catch(IOException e){e.printStackTrace ();} _STB$cZ  
catch(Exception e){e.printStackTrace ();} [//R~i?  
6!iJ;1PeE  
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Utility.log(nFileLength); F,Xo|jjj  
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return nFileLength; Ax3W2s  
} )Ag/Qep  
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//保存下载信息（文件指针位置） z!Q
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private void write_nPos() `+lHeLz':  
{ =bh*[,-  
try{ NY$uq+Z>  
output = new DataOutputStream(new FileOutputStream(tmpFile)); "i.r@<)S  
output.writeInt(nStartPos.length); "yziXT@V  
for(int i=0;i<nStartPos.length;i++) d&cU*  
{ T`/IO.2  
// output.writeLong(nPos); SDG-~(Y  
output.writeLong(fileSplitterFetch.nStartPos); x)rlyjFM  
output.writeLong(fileSplitterFetch.nEndPos); Uv_N x10  
} #0I{.Wy]  
output.close(); |4)  
} 1RLY $M  
catch(IOException e){e.printStackTrace ();} WlB'YL-`g  
catch(Exception e){e.printStackTrace ();} (LvS :?T}  
} $ZPX]2D4B#  
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//读取保存的下载信息（文件指针位置） }y%`)lz~;  
private void read_nPos() o{v&.z  
{ +1C3`0(  
try{ Ph&urxH@  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); F1;lQA*7K.  
int nCount = input.readInt(); 3T\l]? z  
nStartPos = new long[nCount]; fjo{av~]y  
nEndPos = new long[nCount]; {C
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for(int i=0;i<nStartPos.length;i++) 3OyS8`  
{ LL^q1)o  
nStartPos = input.readLong(); ymY1o$qWB}  
nEndPos = input.readLong(); 5OIc(YhYf  
} ,?UM;^  
input.close(); 75!9FqMZ}  
} 5/",<1  
catch(IOException e){e.printStackTrace ();} 6[qA`x#  
catch(Exception e){e.printStackTrace ();} pN6%&@) =  
} W^,S6!  
}*]B-\>  
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private void processErrorCode(int nErrorCode) +j+5ud`  
{ uxn)R#?  
System.err.println("Error Code : " + nErrorCode); 5F+APz7  
} K`}{0@ilCw  
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$
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//停止文件下载 idc`p?XP  
public void siteStop() B@Co'DV[/]  
{ @r(Z%j7  
bStop = true; I-D^>\k+  
for(int i=0;i<nStartPos.length;i++) xVB;s.'!  
fileSplitterFetch.splitterStop(); tary6K9K+  
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} u*S=[dq  
} qIUfPA=/_  
//负责部分文件的抓取 %A1@&xrbl  
**FileSplitterFetch.java R;w
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*/ gie
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package NetFox; Z0!5d<  
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import java.io.*; Zv]x'3J#Y  
import java.net.*; y
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public class FileSplitterFetch extends Thread { Kr'f-{  

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String sURL; //File URL in <(g@Zg  
long nStartPos; //File Snippet Start Position $\o{_?}1  
long nEndPos; //File Snippet End Position vgt]:$  
int nThreadID; //Thread's ID m~#!  
boolean bDownOver = false; //Downing is over NvE}eA#
 
boolean bStop = false; //Stop identical l:;PXy6)  
FileAccessI fileAccessI = null; //File Access interface FLal}80.o:  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException >%p{38  
{ ]=rht9),"  
this.sURL = sURL;
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this.nStartPos = nStart; d4:
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this.nEndPos = nEnd; CQ7{1,?2  
nThreadID = id; 4EI7W,y  
fileAccessI = new FileAccessI(sName,nStartPos);//定位  %R#L  
} e:E0"<  
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public void run() T#%/s?_>.  
{ Sgim3):Z  
while(nStartPos < nEndPos && !bStop) w&$d* E  
{ rt3qdk5U  
# ?1Sm/5k`  
>4Y3]6N0.F  
try{ !IU.a90V  
URL url = new URL(sURL); o56`  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); T J^u"j-'  
httpConnection.setRequestProperty("User-Agent","NetFox"); dF0,Y?  
String sProperty = "bytes="+nStartPos+"-"; a)Q!'$"'  
httpConnection.setRequestProperty("RANGE",sProperty); Xdi:1wW@p  
Utility.log(sProperty); ;Mm7n12z C  
7A\Cbu2tf  
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InputStream input = httpConnection.getInputStream(); WH ?}~u9  
//logResponseHead(httpConnection); 'ckQg=zPR  
/[:dp<  
#Lsnr.80  
byte[] b = new byte[1024]; ~AYN  
int nRead; sb:d>6  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ]3
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{ r
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nStartPos += fileAccessI.write(b,0,nRead); '[$)bPMHl  
//if(nThreadID == 1) 7*j (*  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); gM>t0)mGK  
} L!/\8-&$P  
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7e7 M@8+4  
Utility.log("Thread " + nThreadID + " is over!"); =/<LSeLxH  
bDownOver = true; 1}hIW":3Sr  
//nPos = fileAccessI.write (b,0,nRead); 4%WzIzRb  
} ~/NKw:  
catch(Exception e){e.printStackTrace ();} ZZQG?("S'  
} i'd2[A.7I  
} KKA~#iCk  
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//打印回应的头信息 _0+0#! J!  
public void logResponseHead(HttpURLConnection con) jR=s#Xz  
{ >56>*BHD  
for(int i=1;;i++) $'W}aER  
{ &aM7T_h8  
String header=con.getHeaderFieldKey(i); GdB.4s^  
if(header!=null) ob+euCuJ  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); f>'Y(dJ'W  
Utility.log(header+" : "+con.getHeaderField(header)); 01!s"wjf  
else V)Z70J<'  
break; d]9U^iy  
} Iff9'TE  
} '65LKD  
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public void splitterStop() f}guv~K  
{ =U|N=/y#hJ  
bStop = true; gTRF^knrY  
} wf,7==  
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} yH][(o=2  
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/* .CP&bJP%  
**FileAccess.java :Xc@3gF  
*//文件访问(定位，写) I ZQHu h  
package NetFox; !lo/xQ<  
import java.io.*; /0\ mx4u  
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t6v/sZ{F  
public class FileAccessI implements Serializable{ j*xV!DqC  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 E2)h?cs  
RandomAccessFile oSavedFile; x8GJY~:SW  
long nPos; fnx-s{c?  
f
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public FileAccessI() throws IOException .`?@%{  
{ \.M*lqI  
this("",0); TLehdZ>^  
} @cU&n6C@  
%`Z!4L  
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public FileAccessI(String sName,long nPos) throws IOException (sWLhUgRX  
{ G[jW
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oSavedFile = new RandomAccessFile(sName,"rw"); E*i#?u  
this.nPos = nPos; _X?^Cy  
oSavedFile.seek(nPos); ctcS:<r/3@  
} V|\7')Qq  
qZ@s#UiB  
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public synchronized int write(byte[] b,int nStart,int nLen) yCCrK@{oo  
{ r(gXoq_w  
int n = -1; !?Wp+e6  
try{ }@.|?2b +  
oSavedFile.write(b,nStart,nLen); FLEo*9u>b  
n = nLen; ]qhPd_$?D'  
} ~/j\Z  
catch(IOException e) 7gRgOzWfV  
{ #Fyuf,hw4  
e.printStackTrace (); LR"9D
 
} YuB+k^  
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return n; eYx Kp!f  
} tBpC: SG  
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} 7g_]mG[6  
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/* O*#*%RL|  
**SiteInfoBean.java vTn}*d.K=  
*/ iYC9eEF  
package NetFox; ToYAW,U[d  
47J5oPT2'  
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public class SiteInfoBean { 8V~vXnkM  
 T Q,?>6n  
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private String sSiteURL; //Site's URL e1P"[|9>R  
private String sFilePath; //Saved File's Path 7g3>jh  
private String sFileName; //Saved File's Name ;J7F J3n  
private int nSplitter; //Count of Splited Downloading File {z|;Xi::"  
.`&F>o(A  
5ZBKRu  
public SiteInfoBean() H/}]FmjN  
{//nSplitter的缺省值为5 * RtgC/  
//default value of nSplitter is 5 *?MGMhE  
this("","","",5); fDLG>rXPT  
} =FD;~  
Ha)ANAD  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter)
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{
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sSiteURL= sURL; T1H"\+  
sFilePath = sPath; J`2"KzR0w"  
sFileName = sName; )m. 4i=X  
this.nSplitter = nSpiltter; 7B?c{  
&\_iOw8  
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} MHa#?Q9  
*z7dl5xJ  
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public String getSSiteURL() dUsxvho  
{ --DoB=5%8  
return sSiteURL; ?Q&yEGm(  
} _Zr.ba  
b".L_Ma1*  
}1rm  
public void setSSiteURL(String value) YID4w7|  
{ c_>f0i  
sSiteURL = value; ?R$&Xe!5  
} p'om-  
+zs4a96[  
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public String getSFilePath() z<5m fAm  
{ =Qn ;_+Ct  
return sFilePath; $.bBFWk  
} 9H%X2#:fH  
h;0S%ZC  
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public void setSFilePath(String value) +$Rt+S BD  
{ )(@Hd  
sFilePath = value; 7hcNf,  
} /J
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1m.W<  
public String getSFileName() 3g6j?yYqb  
{ ()H:UvM=t  
return sFileName; ^I+)o1%F  
} *2GEnAZb7n  
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h5K$mA5  
public void setSFileName(String value) CoA6  
{ 8}(]]ayl  
sFileName = value; xL" |)A =  
} I&YSQK:b  
:GJ &_YHf  
& j+oJasI  
public int getNSplitter() M8TSt\  
{ -neKuj  
return nSplitter; uAWM\?  
} Zcc9e03  
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public void setNSplitter(int nCount) :Q@&5!]>d  
{ +k>.Q0n%m  
nSplitter = nCount; b4pm_Um  
} =ha{Ziryo  
} &:7ZQ1  
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Ft!],n-n*  
/* Tq~=TSD  
**Utility.java vz!s~cAt  
*/ 71{p+3Z&  
package NetFox; k|!EDze43?  
O &-wxJ]S  
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public class Utility { 9cj9SB4  

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%?Ev|:i`@  
public Utility() ~T89_L  
{ @qHNE,K  
6!(@@^7{*  
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} ,zTy?OQ  
(zFi$  
//线程睡眠 k Zq!&  
public static void sleep(int nSecond) &EnuE0BD  
{ Pp5^@A  
try{ lO_UPC\@fw  
Thread.sleep(nSecond); %p0xM  
} {qa Aq%'  
catch(Exception e) h?azFA~  
{ C;vtY[}<  
e.printStackTrace (); Vkc#7W(  
} w/K_B:s  
} aVd,xl  
:]1TGfS  
//日志 2Roc|)-47  
public static void log(String sMsg) Kp,M"Y  
{ -Zz$~$  
System.err.println(sMsg); Xqm:
:1(-(  
} .>IhN 5  
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_> *jH'  
public static void log(int sMsg) !U~WK$BP  
{ $ <#KA3o\  
System.err.println(sMsg); ,9o"43D:a|  
} ok4@N @  
} bAm(8nT7w  
}7.PH'.8  
;y2/-tL?  
/* d:U9pC$  
**TestMethod.java [`):s= FC  
*/ GHeVp/u  
package NetFox; se>MQM5 )  
'&|=0TDd+  
_Iv6pNd/  
public class TestMethod { L~NbdaO  
8UVmv=T  
;IokThI  
public TestMethod() sK5r$Dbr  
{ ///xx/weblogic60b2_win.exe ZKckAz\#  
try{ 2j[&=R/.  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); aWY g
R  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); !!? Mw  
SiteFileFetch fileFetch = new SiteFileFetch(bean); BFOq8}fX2  
fileFetch.start(); HZf/CE9T  
} '4#}e[e  
catch(Exception e){e.printStackTrace ();} jYhB +|  
jWE:ek*  
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} ?CA,  
cu/5$m?xx  
9*1,!%]  
public static void main(String[] args) ML>[^F  
{ W!>.$4Q9  
new TestMethod(); u[ Yk  
} 6gs01c,BA  
}  #c66)  
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