http断点续传简单实现（java)

/* g5y`XFY  
**SiteFileFetch.java g<(!>
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*/ [.^ol6  
package NetFox; f]#\&"  
import java.io.*; a7c`[   
import java.net.*; ^utOVi  
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public class SiteFileFetch extends Thread { *~g*J^R
}  
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SiteInfoBean siteInfoBean = null; //文件信息Bean &:5*^1oP  
long[] nStartPos; //开始位置 h$kz3r;b,"  
long[] nEndPos; //结束位置 =]]1x_GB  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 %SOXw8-  
long nFileLength; //文件长度 Nd]F 33|X  
boolean bFirst = true; //是否第一次取文件 '=vZAV`  
boolean bStop = false; //停止标志 )M
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File tmpFile; //文件下载的临时信息 d_d&su E  
DataOutputStream output; //输出到文件的输出流 ?[d4HKs  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） w") G:K  
public SiteFileFetch(SiteInfoBean bean) throws IOException j
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{ BW7AjtxQ&  
siteInfoBean = bean; O_8 SlW0e  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); L4Zt4Yuw  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); &RYdSXM  
if(tmpFile.exists ()) kW)3naUf<  
{ o *J*}y  
bFirst = false; Ny2 Z <TW  
read_nPos(); ]5jS6@Vl*  
} jcJ 4?  
else &'$Bk5D@G  
{ 9^W7i]-Z  
nStartPos = new long[bean.getNSplitter()]; V*b/N  
nEndPos = new long[bean.getNSplitter()]; Q__CW5&'u  
} EW*sTI3  
#zTy7ZS,0  
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} yuZLsH  
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public void run() EL`|>/
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{ [*^.$s(  
//获得文件长度 aO(PVS|P  
//分割文件 ~D9Cu>d9  
//实例FileSplitterFetch \W.CHSD  
//启动FileSplitterFetch线程 `.MZ,Xhqi"  
//等待子线程返回 OP1`!P y  
try{ d5l42^Z  
if(bFirst) 6^gp /{  
{ LZn'+{\`  
nFileLength = getFileSize(); kM506U<g  
if(nFileLength == -1) Cjf[]aNJe`  
{ +r3)\L{U  
System.err.println("File Length is not known!"); ML_VD*t9  
} 9m M3Ve*  
else if(nFileLength == -2) Ma|4nLC}  
{ W^[FWFUTY  
System.err.println("File is not access!"); *)Qv;'U=rn  
} Q-w# !<L.  
else "tCTkog3]  
{ O6hzOyNX@  
for(int i=0;i<nStartPos.length;i++) 0#8  
{ l1 Kv`v\  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); z?\it(  
} ELCNf  
for(int i=0;i<nEndPos.length-1;i++) _iJ~O1qx,w  
{ BTkx}KK  
nEndPos = nStartPos[i+1]; 2%pED xui  
} P$obID  
nEndPos[nEndPos.length-1] = nFileLength; mU #F>  
} vUpAW[[  
} (L/>LZn|  
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{]Zan'{PCO  
//启动子线程 3s%?)z  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; XR+ SjCA  
for(int i=0;i<nStartPos.length;i++) %)lp]Y33  
{ jA{5)-g  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), }Ja-0v)Wf  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), <K[y~9u  
nStartPos,nEndPos,i); #3rS{4[  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ;MS.ag#  
fileSplitterFetch.start(); Pzs
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} kZw"a*6  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), gI^&z  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Pp_4B  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", <<>+z5D+  
nEndPos = " + nFileLength); XG/xMz~  
// fileSplitterFetch[nPos.length-1].start(); z(\aJW  
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LIID(s!bX  
//等待子线程结束 yLC[-.H  
//int count = 0; Z Ts*Y,  
//是否结束while循环 :TQp,CEa  
boolean breakWhile = false; T3{O+aRt  
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while(!bStop) B"GC|}N)v  
{ XJ<"S p  
write_nPos(); /I7V\  
Utility.sleep(500); wp?:@XM  
breakWhile = true; j[r}!;O  
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for(int i=0;i<nStartPos.length;i++) xvTtA61Vp  
{ , /.@([C  
if(!fileSplitterFetch.bDownOver) =7Ud-5c  
{ Nn05me"X  
breakWhile = false; #p(gB)o:l  
break; OR@ 67Y  
} #kW=|8X  
} g6Vkns4  
if(breakWhile)
{"wF;*U.V  
break; [K4cxqlfk  
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//count++; tYD8Y  
//if(count>4) *u$aItx  
// siteStop(); I
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} MJ:c";KCq0  
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System.err.println("文件下载结束！"); NN4Z:6W5  
} !`{?qQ[=  
catch(Exception e){e.printStackTrace ();} Wg}KQ6 6  
} 7\UHADr  
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//获得文件长度 0fqcPi  
public long getFileSize() )la3GT*1mS  
{ FF8jW1  
int nFileLength = -1; 5Dkb/Iagi  
try{ b~.$1oZ  
URL url = new URL(siteInfoBean.getSSiteURL()); WM+8<|)n  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); B!&5*f}*  
httpConnection.setRequestProperty("User-Agent","NetFox"); VD.TosVeWo  
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int responseCode=httpConnection.getResponseCode(); UuIjtqW  
if(responseCode>=400) *8)?ZZMM  
{ aqSOC(jU  
processErrorCode(responseCode); m'2F#{  
return -2; //-2 represent access is error >M5}L<  
} U.TZd"  
|)7K(R)(=  
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String sHeader;  m}yu4  
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for(int i=1;;i++) ( %7V  
{ >"/TiQt  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); #.Dl1L/  
//Utility.log(in.readLine()); F.TIdkvp  
sHeader=httpConnection.getHeaderFieldKey(i); ytj});,>  
if(sHeader!=null) OXLB{|hH80  
{ E]q>ggeNH  
if(sHeader.equals("Content-Length")) IEm?'o:  
{ OG
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); }e7/F[c.U  
break; \B')2phE  
} i<S
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} bAt!S  
else `pbCPa{Y  
break; H'S~GP4D  
} D?ic~-&  
} JSg=9p$  
catch(IOException e){e.printStackTrace ();} bN?*p($/  
catch(Exception e){e.printStackTrace ();} *effDNE!  
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Utility.log(nFileLength); -~.+3rcZ]  
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return nFileLength; ,JH*l:
7  
} e`+  
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//保存下载信息（文件指针位置） k&yBB%g  
private void write_nPos() nILUo2e~  
{ `
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try{ +4t \j<T  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 4-O.i\1q  
output.writeInt(nStartPos.length); S%p,.0_  
for(int i=0;i<nStartPos.length;i++) GF9iK|i/  
{ d>M0:  
// output.writeLong(nPos); f[zKA{R  
output.writeLong(fileSplitterFetch.nStartPos); %.[AZ>  
output.writeLong(fileSplitterFetch.nEndPos); O0^Y1l  
} GLY,
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output.close(); ]mBlXE:Z  
} =]Y'xzJuu  
catch(IOException e){e.printStackTrace ();} Q-_;.xy#4  
catch(Exception e){e.printStackTrace ();} ;|rFP  
} Jv2V@6a(  
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//读取保存的下载信息（文件指针位置） OwC{ Ad{  
private void read_nPos() '&/Y}]  
{ ~O;?;@  
try{ MMRO@MdfV  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); w4y???90)  
int nCount = input.readInt(); 1g!%ej jd  
nStartPos = new long[nCount]; F8m@mh*8>  
nEndPos = new long[nCount]; ~}YgZ/U7T  
for(int i=0;i<nStartPos.length;i++) ^YPw'cZZ&  
{ Y$q--JA  
nStartPos = input.readLong(); {flxZ}  
nEndPos = input.readLong(); :fG9p`  
} nNM)rW  
input.close(); e]jzFm~  
} mpCKF=KL.  
catch(IOException e){e.printStackTrace ();} @(st![i+  
catch(Exception e){e.printStackTrace ();} >*w(YB]/$V  
} ?IG+U TI  
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private void processErrorCode(int nErrorCode) jK=-L#hz  
{ e3&.RrA  
System.err.println("Error Code : " + nErrorCode); 3Z)vJC9'  
} & V/t0  
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//停止文件下载 EJrQ9"x&n  
public void siteStop() g|3FJA/  
{ FJ&?My,=J  
bStop = true; gJn_8\,C>Q  
for(int i=0;i<nStartPos.length;i++) l< |)LDq~  
fileSplitterFetch.splitterStop(); u-Ip*1/wp  
{,m W7  
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} 0/%VejZ'  
} tTrue?  
//负责部分文件的抓取 Q,f5r%A.  
**FileSplitterFetch.java W[W}:@KZ  
*/ n47v5.Wn  
package NetFox; $
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import java.io.*; 5SY(:!  
import java.net.*; G&*2h2,]  
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public class FileSplitterFetch extends Thread { cz9T,  
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String sURL; //File URL 3+jqf@fO  
long nStartPos; //File Snippet Start Position fL&bN[XA"$  
long nEndPos; //File Snippet End Position y|%rW  
int nThreadID; //Thread's ID +lqX;*a=N  
boolean bDownOver = false; //Downing is over 7l3sd5  
boolean bStop = false; //Stop identical 2^7VDqLc  
FileAccessI fileAccessI = null; //File Access interface ',p`B-dw  
{)0"?$C_H  
*<_8]C0>  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 3v%V\kO=F  
{ 9rmOf Jo:  
this.sURL = sURL; <J QvuC  
this.nStartPos = nStart; 3Ga!)  
this.nEndPos = nEnd; h~ =UFE%'  
nThreadID = id; _YW1Mk1  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 x;Jy-hMNl  
} ^i^/d#  
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public void run() 3X&}{M:Qo  
{ aD@sb o  
while(nStartPos < nEndPos && !bStop) :)\<  
{ j9YI6X"  
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try{ G~I@'[ur  
URL url = new URL(sURL); ^U.8grA  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); RAQi&?Ko  
httpConnection.setRequestProperty("User-Agent","NetFox"); [s4lSGh  
String sProperty = "bytes="+nStartPos+"-"; )q\|f_  
httpConnection.setRequestProperty("RANGE",sProperty); hp]T^  
Utility.log(sProperty); fKMbOqU_  
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InputStream input = httpConnection.getInputStream(); "Fu*F/KW  
//logResponseHead(httpConnection); 7W6tz\Y  
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byte[] b = new byte[1024]; X9#;quco@  
int nRead;
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ~1
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{ A7|!&fi  
nStartPos += fileAccessI.write(b,0,nRead); MS-}IHO  
//if(nThreadID == 1) $UAmUQg)}_  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); W|oLS  
} R g7 O  
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Utility.log("Thread " + nThreadID + " is over!"); E4aCL#}D  
bDownOver = true; e.%` tK3J  
//nPos = fileAccessI.write (b,0,nRead); V^W
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} L<encPJt  
catch(Exception e){e.printStackTrace ();} _6"!y ]Q  
} K)c`G_%G  
} j()<.h;'  
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//打印回应的头信息 TOp|Qtn  
public void logResponseHead(HttpURLConnection con) \-Mzs 0R  
{ <taN3  
for(int i=1;;i++) tY^MP5*  
{ L,L>cmpM  
String header=con.getHeaderFieldKey(i); {#aW")x^#  
if(header!=null) ?r"'JO.w  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); YoV^Y&:9<  
Utility.log(header+" : "+con.getHeaderField(header)); h=uwOi6}  
else 8jW"8~Y#0  
break; E(F<s
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} PMzPe"3M  
} E Z95)pk  
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#;59THdtPk  
public void splitterStop() #%t&f"j2  
{ 5|>FM&  
bStop = true; 'xi[- -  
} dYdZt<6W<(  
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} EY=`/~|c  
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/* 5 Z
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**FileAccess.java ;fL
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*//文件访问(定位，写) vovc,4}  
package NetFox; $xRZU9+  
import java.io.*; S&]AIG)  
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public class FileAccessI implements Serializable{ #-b0U[,.  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Y
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RandomAccessFile oSavedFile; >*#clf;@p  
long nPos; C{mL]ds<  
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public FileAccessI() throws IOException X=O}k&  
{ X2>qx^jT  
this("",0); 6E~T$^Q}  
} )c vA}U.z  
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public FileAccessI(String sName,long nPos) throws IOException m/W0vPM1  
{ %n<u-
{`  
oSavedFile = new RandomAccessFile(sName,"rw"); Z|&Y1k-h  
this.nPos = nPos; ^6*LuXPv  
oSavedFile.seek(nPos); Ul@Jg    
} &w@~@]  
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public synchronized int write(byte[] b,int nStart,int nLen) pAwmQ
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{ o(iv=(o  
int n = -1; a o_A%?Ld  
try{ n^OWz4  
oSavedFile.write(b,nStart,nLen); ^<L;"jl%  
n = nLen; xsjJ8>G  
} {4u8~whLp  
catch(IOException e) E]x)Qr2Ju  
{ ofeSGx  
e.printStackTrace (); H`!%"  
} 0fc]RkHs"  
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ppcuMcR{  
return n; YXC?q  
} CV<@Rgoa  
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} QW~-+BD  
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/* J:M)gh~#  
**SiteInfoBean.java Z Mp  
*/ TF %8pIg>Z  
package NetFox; @d5G\1(%  
}NQx2k0  
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public class SiteInfoBean { F">>,Oc)U"  
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|.D_[QI  
private String sSiteURL; //Site's URL o!Vs{RRu
}  
private String sFilePath; //Saved File's Path ;0}8vs  
private String sFileName; //Saved File's Name -"L)<J@gQ?  
private int nSplitter; //Count of Splited Downloading File =m@5$  
kqYvd]ss  
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public SiteInfoBean() z~d\d!u1  
{//nSplitter的缺省值为5 #k%3Ag  
//default value of nSplitter is 5 Ed/@&52z0  
this("","","",5); G@
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} M4a-+T"  
7#Qa/[? D  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) #80*3vi~F  
{ *"E?n>b  
sSiteURL= sURL; &k3'UN!&Ix  
sFilePath = sPath; Meh?FW||5  
sFileName = sName; )2X ng_,  
this.nSplitter = nSpiltter; "AjtNL5  
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} 4+mawyM  
nbYkr*: "t  
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public String getSSiteURL() =+gp~RR,  
{ z`uqK!v(K  
return sSiteURL; ;_0)f
 
} +j5u[X  
p
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public void setSSiteURL(String value) 
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{ >Uvtsj#  
sSiteURL = value; N$ZThZqqv  
} xmtbSRgK9  
uK]@!gz  
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public String getSFilePath() wxZnuCO%H8  
{ &)Z8Qu  
return sFilePath; jG{}b6  
} uVqJl{e\  
 $JmL)r  
uMF\3
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public void setSFilePath(String value) UQ>GAzh  
{ .Gl&K|/{j  
sFilePath = value; o]#Q6J  
} $XFG1?L!  
\E.t=XBn  
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public String getSFileName() {549&]/o  
{ QN-n9f8  
return sFileName; `.%;|"xR  
} NpD}7t<EF  
^iubqtT]  
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public void setSFileName(String value) 2Z@<llsi  
{ (W+9 u0Zq  
sFileName = value; L5yxaF{]  
} UF<|1;'  
|f8by\Q86=  
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public int getNSplitter() sNvT0  
{ B\|>i~u(  
return nSplitter; /_,
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} = k3O4gE7  
:G^`LyOM  
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public void setNSplitter(int nCount) B<1*p,z  
{ 94APjqV6'  
nSplitter = nCount; <zZAVGb4I  
} c7s4 g-  
} 2)A D'  
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/* &f yFUg  
**Utility.java
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*/ {_~G+rqY  
package NetFox; ]]Z,Qu#<-  
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public class Utility { ?>y-5B[K/(  
) G{v>Z,  
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public Utility() w!}1oy  
{ K_5&_P1  
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)ziQ=k6d6  
} (<l2 ^H  
c-.>C)  
//线程睡眠 lnDDFsA  
public static void sleep(int nSecond) kpH;D=;  
{ hwzUCh 5!  
try{ JY2 F-0t)  
Thread.sleep(nSecond); ;}~=W!yz  
} \V>%yl{8  
catch(Exception e) .=yus[,~  
{ HD{`w1vcN  
e.printStackTrace (); .m?~TOR  
} Xa@wN/"F  
} *d@Hnu"q  
GC[{=]}9U  
//日志 EKPTDKut  
public static void log(String sMsg) `yAo3A9vk  
{ jw[
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System.err.println(sMsg);  +Rgw
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} 0Qp'}_  
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D:E~yh)$-  
public static void log(int sMsg)  <%D"eD  
{ Sx)Il~ x  
System.err.println(sMsg); kI3zYD^:  
} `4H9f&8(  
} 6I.mc  
r`&|)Hx  
i=UTc1  
/* .w_`d'}  
**TestMethod.java "O[76}I+.q  
*/ y,?G75wij  
package NetFox; %hbLT{w  
IZ0$=aB7  
RVnyl`s  
public class TestMethod { 5u_4lNJ&  
B21AcE  
RzRvu]]8  
public TestMethod() 'ZH<g8:=@  
{ ///xx/weblogic60b2_win.exe +;*(a3Gp  
try{ 4l}M i  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); NWHH.1|  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Ws*PMK.0  
SiteFileFetch fileFetch = new SiteFileFetch(bean); G;HlII9x[  
fileFetch.start(); oPu|Q^I=  
} a\69,%!:  
catch(Exception e){e.printStackTrace ();} 0r-lb[n8i  
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} '}+X,Usm  
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public static void main(String[] args) KTK6#[8A  
{ @`;Y/',  
new TestMethod(); 2v9s@k/k)6  
} rrY{Jf9>  
} ]X: rby$  
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