http断点续传简单实现（java)

/* 7I;A5f  
**SiteFileFetch.java 7?W
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*/ @0&KM|+  
package NetFox; Ro
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import java.io.*; vH)V
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import java.net.*; `Ti?hQm/  
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public class SiteFileFetch extends Thread { c#<p44>U  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ,]H2F']4Z  
long[] nStartPos; //开始位置 :V ZXI#([  
long[] nEndPos; //结束位置 Z,JoxK2"  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 E9~}%&  
long nFileLength; //文件长度 PCs`aVZ  
boolean bFirst = true; //是否第一次取文件 H%G|8,4  
boolean bStop = false; //停止标志 hyVBQhk  
File tmpFile; //文件下载的临时信息 %pBc]n
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DataOutputStream output; //输出到文件的输出流 4ZCD@C  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Xcw6mpLt  
public SiteFileFetch(SiteInfoBean bean) throws IOException NGL,j\(~7  
{ @*^%^ P  
siteInfoBean = bean; hzV= 7  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); L,_Z:\^  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); k r ga!,I  
if(tmpFile.exists ()) bD4aSubN  
{ .)[0yW&  
bFirst = false; . l-eJ  
read_nPos(); [/GCy0jk  
} n?}7vz;  
else :e!3-#H  
{  @s7wKk  
nStartPos = new long[bean.getNSplitter()]; i>{.Y};  
nEndPos = new long[bean.getNSplitter()]; DTo P|P  
} kJk6lPSqi7  
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} _0h)O  
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public void run() {N'<_%cu  
{ 
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//获得文件长度 'j'G4P_G  
//分割文件 ]CGH )4Pe  
//实例FileSplitterFetch [iUy_ C=qp  
//启动FileSplitterFetch线程 7QM1E(cMg  
//等待子线程返回 z2IKd'Wy  
try{ 5\.w\  
if(bFirst) LtVIvZie  
{ L7PMam  
nFileLength = getFileSize(); 6YF<GF{  
if(nFileLength == -1) n#"N"6s  
{ PsO>&Te2  
System.err.println("File Length is not known!"); fX{Xw0  
} e_3($pj  
else if(nFileLength == -2) 5#BM  
{ P\{}yd  
System.err.println("File is not access!"); &h'NC%
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} q"Th\? }%  
else 5nS}h76mZ  
{ H{I,m-  
for(int i=0;i<nStartPos.length;i++) Y[.f`Ei2  
{ |oX1J<LM  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); o[
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} O~4Q:#^c  
for(int i=0;i<nEndPos.length-1;i++) *yqke<o9)  
{ Wo7`gf_(  
nEndPos = nStartPos[i+1]; 5Mz6/&`  
} vEC#W43l  
nEndPos[nEndPos.length-1] = nFileLength; .Zm de*b  
} *^i"q\n5(  
} 1HBWOV7z.?  
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//启动子线程 =i:,")W7=  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; $ 9 k5a  
for(int i=0;i<nStartPos.length;i++) ^a?g~G  
{ X]c>clk,  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), X6so)1jJ  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), r:--DKt  
nStartPos,nEndPos,i); Q9{f'B  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .tA=5QY,  
fileSplitterFetch.start(); NKMVp/66D  
} d-'BT(@:  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), EqF>=5*  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); h.4FY<  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", `i)Pf WdBN  
nEndPos = " + nFileLength); >6Ody<JPHP  
// fileSplitterFetch[nPos.length-1].start(); q_z;kCHM  
=h,J!0Y  
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//等待子线程结束 `2hLs _  
//int count = 0; n*rXj{Kt  
//是否结束while循环 .Z(Q7j^  
boolean breakWhile = false; (N?nOOQ  
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while(!bStop) zvR;Tl6]  
{ iiv`ji  
write_nPos(); C@!bd+'  
Utility.sleep(500); m*vz   
breakWhile = true; _71&".A  
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for(int i=0;i<nStartPos.length;i++) (je`sV  
{ j9f[){m`  
if(!fileSplitterFetch.bDownOver) "GX k;Y  
{ He1~27+99  
breakWhile = false; F0ylJ /E  
break; hq?F81  
} ZwMd 22  
} =}'7}0M_=  
if(breakWhile) 2?kVbF  
break; D*t[5,~j  
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//count++;
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//if(count>4) p<c1$O*  
// siteStop(); &"d :+!4h  
} vDC
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System.err.println("文件下载结束！"); A9y@v{tx
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} ]sJjV A  
catch(Exception e){e.printStackTrace ();} Uj^Y\w-@Z  
} j+[
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//获得文件长度 &"DD&87N%  
public long getFileSize() {Zo*FZcaX  
{ B/dJj#  
int nFileLength = -1; 9qm'qx  
try{ pER[^LH_)  
URL url = new URL(siteInfoBean.getSSiteURL()); M
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ?N]G;%3/  
httpConnection.setRequestProperty("User-Agent","NetFox"); W/.Wp|C}K3  
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int responseCode=httpConnection.getResponseCode(); y\Wp}}  
if(responseCode>=400) .t.4y. 97  
{ ='6@^6y  
processErrorCode(responseCode); 3j2d&*0  
return -2; //-2 represent access is error
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} R'qBG(?i  
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String sHeader; )kIjZ  
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for(int i=1;;i++) FpZ5@  
{ ,.AXQ#~&`  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); >nO[5  
//Utility.log(in.readLine()); 1rV9dM#F  
sHeader=httpConnection.getHeaderFieldKey(i); 7pM&))
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if(sHeader!=null) b6g/SIae  
{ c*",AZ>
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if(sHeader.equals("Content-Length")) 1;HL=F
  
{ 2]}e4@{  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); mh35S!I3I^  
break; 5hfx2O)  
} J9P\D!  
} GQ}R
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else wsgT`M'J[  
break; @B9#Hrc  
} w:2yFC  
} ]W7&ZpF  
catch(IOException e){e.printStackTrace ();} O@>{%u  
catch(Exception e){e.printStackTrace ();} n/^QPR$>.  
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Utility.log(nFileLength); R)Dh;XA  
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return nFileLength; `+(4t4@ew  
} \wV
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}]. |7h  
//保存下载信息（文件指针位置） 0G3T.4I  
private void write_nPos() EGjzjuJu{  
{ AjINO}b  
try{ !X 0 (4^  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ' wKTWmf?\  
output.writeInt(nStartPos.length); |sBL(9  
for(int i=0;i<nStartPos.length;i++) -v=tM6  
{ |T{ZDJ+  
// output.writeLong(nPos); 5#::42oE  
output.writeLong(fileSplitterFetch.nStartPos); iOiXo6YE  
output.writeLong(fileSplitterFetch.nEndPos); Hn
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} Z|j\_VKhl  
output.close(); p7[&H/  
} a KIS%M#Y  
catch(IOException e){e.printStackTrace ();} 4|NcWpaV7  
catch(Exception e){e.printStackTrace ();} 0$|wj^?U  
} soqnr" 1  
#!4`t]E<  
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//读取保存的下载信息（文件指针位置） xI8v'[3  
private void read_nPos() e*o:ltP./  
{ P7!gUxcv9Y  
try{ \>+BvF  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); JB HnJm  
int nCount = input.readInt(); r6L  
nStartPos = new long[nCount]; !%QbE[Kl>  
nEndPos = new long[nCount]; Tx/KL%X  
for(int i=0;i<nStartPos.length;i++) !={QL:  
{ ]%UAN_T  
nStartPos = input.readLong(); n yNHjn |W  
nEndPos = input.readLong(); jyC>~}?  
} hcQv!!Q"k$  
input.close(); |2&|#K4k^  
} S.^x)5/,,T  
catch(IOException e){e.printStackTrace ();} }t
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catch(Exception e){e.printStackTrace ();} 7G_OFD  
} 8TO5j  
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private void processErrorCode(int nErrorCode) v[>8<z8  
{
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System.err.println("Error Code : " + nErrorCode); !DeU8.%  
} @4jPaqa(  
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//停止文件下载 osTin*T.  
public void siteStop() A{Q~@1  
{ #b{;)C fL  
bStop = true; g")pvK[e  
for(int i=0;i<nStartPos.length;i++) g'V,K\TG  
fileSplitterFetch.splitterStop(); EZ^M?awB4  
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} Wl3fR[@3Q  
} OoR0>!x Z  
//负责部分文件的抓取 T4}q%%7l  
**FileSplitterFetch.java %`:+A?zL  
*/ KQ.cd]6  
package NetFox; IFWP&20  
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import java.io.*; Y+"Gx;F>  
import java.net.*; qFjnuQ,w  
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public class FileSplitterFetch extends Thread { I^S{V^Ty  
6}PoBhgSg-  
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String sURL; //File URL }pv<<7}|  
long nStartPos; //File Snippet Start Position 5VW*h  
long nEndPos; //File Snippet End Position ow,=M%x"0  
int nThreadID; //Thread's ID |HK/*B  
boolean bDownOver = false; //Downing is over l # F.S5i  
boolean bStop = false; //Stop identical GK:pt8=  
FileAccessI fileAccessI = null; //File Access interface U`ELd:  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {NV=k%MTmi  
{ -Tr*G4  
this.sURL = sURL; Q?W}]RW  
this.nStartPos = nStart; 1FmVx  
this.nEndPos = nEnd; cGe-|>:  
nThreadID = id; JU0|pstf  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 )L:p.E  
} u< .N\/  
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public void run() 04R-}  
{ C?%Oi:Gi&  
while(nStartPos < nEndPos && !bStop) 1fb!sbGD.k  
{ `oo(\O7t=  
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try{ d<4q%y'X{  
URL url = new URL(sURL); nD;8)VI'I  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); fHwr6"DJ  
httpConnection.setRequestProperty("User-Agent","NetFox"); \}mn"y  
String sProperty = "bytes="+nStartPos+"-"; \~'+TW  
httpConnection.setRequestProperty("RANGE",sProperty); P[C03a!lXg  
Utility.log(sProperty); a]_eSU@  
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InputStream input = httpConnection.getInputStream(); a,*~wmg  
//logResponseHead(httpConnection); 1]Gp\P}  
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byte[] b = new byte[1024]; +46?+kKt  
int nRead; 3
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) z8hAZ?r1`  
{ :HG5{zP  
nStartPos += fileAccessI.write(b,0,nRead); rui]_Fn]I  
//if(nThreadID == 1) -dsE9)&8DX  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ]AzDkKj  
} uPtS.j=  
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Utility.log("Thread " + nThreadID + " is over!"); \)n'Ywr  
bDownOver = true; >0qe*4n|M  
//nPos = fileAccessI.write (b,0,nRead); iu6NIy7D  
} . 'rC'FT  
catch(Exception e){e.printStackTrace ();} SV96eYT<  
} Vy[ m%sEP  
} |#=4]]>m  
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//打印回应的头信息 Rck k  
public void logResponseHead(HttpURLConnection con) )YP9  
{ "kT?9&  
for(int i=1;;i++) wsLfp82  
{ Ykd< }KE>  
String header=con.getHeaderFieldKey(i); =HkB>w)h  
if(header!=null) x4vowF  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ..hD_k  
Utility.log(header+" : "+con.getHeaderField(header)); JgY#W1>  
else /xcl0oe
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break; N61\]BN<  
} r*t\\
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} BTu_$5F  
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public void splitterStop() COf>H0^%Q  
{ .IJgkP)!]  
bStop = true; ESAFsJ$r;  
} s5'So@L8  
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} -<tfbaA  
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/* _YgvLz %  
**FileAccess.java J_PbRb  
*//文件访问(定位，写) b)Px  
package NetFox; oCftI':@  
import java.io.*; o|BEY3|  
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public class FileAccessI implements Serializable{ =fr_` "?k  
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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 x:O;Z~ |.  
RandomAccessFile oSavedFile; 12,,gwh  
long nPos; >1n[Y- r  
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public FileAccessI() throws IOException CAl]Kpc  
{ n@Ar%%\  
this("",0); 3r(i=ac0  
} H_CX5=Nq^  
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public FileAccessI(String sName,long nPos) throws IOException ?yq1\G)]  
{ .s!qf!{V`  
oSavedFile = new RandomAccessFile(sName,"rw"); eBW=bK~[VP  
this.nPos = nPos; !w9w{dtW=  
oSavedFile.seek(nPos); ?A4t &4  
} `Mxi2Y{vp  
3M[b)At V.  
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public synchronized int write(byte[] b,int nStart,int nLen) h^}r$k_n  
{ dwc$#cMf  
int n = -1; igD,|YSK`z  
try{ i!
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oSavedFile.write(b,nStart,nLen); CF:s@Z+  
n = nLen; |4@su"OA  
} c)tG1|Og]  
catch(IOException e) voHFU#Z$  
{ WTcrfs)T  
e.printStackTrace (); /=bg(?nX  
} CI )89`  
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return n; 0cwb^ffN  
} e5 ?;{H  
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} [*k25N  
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/* kCu"G  
**SiteInfoBean.java ~X`_g/5X  
*/ };:+0k/  
package NetFox; {|kEGq~aE  
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6?3f+=e"~!  
public class SiteInfoBean { =V@5W[bV  
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private String sSiteURL; //Site's URL ^rmcyy8;g  
private String sFilePath; //Saved File's Path .<<RI8A  
private String sFileName; //Saved File's Name YjTRz.e{[7  
private int nSplitter; //Count of Splited Downloading File P@m_tA%  
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public SiteInfoBean() d%y)/5  
{//nSplitter的缺省值为5 =q%Q^  
//default value of nSplitter is 5 b6FC  
this("","","",5); }J~ d6m  
} R<J1bH1n3  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) <@DF0x!  
{ O]>FNsh!  
sSiteURL= sURL; LovVJ^TD0i  
sFilePath = sPath; ^Lx(if WJ  
sFileName = sName; _NfdJ=[Xh  
this.nSplitter = nSpiltter; \lJCBb+k  
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} 5@YrtZI  
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public String getSSiteURL() s+@+<QE  
{ (9#$za>  
return sSiteURL; *?2aIz"  
} &DX&*Xq2  
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public void setSSiteURL(String value) 1%v!8$  
{ PJ-EQ6W  
sSiteURL = value;  zz)[4G  
} KlMSkdmW  
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public String getSFilePath() 4@iMGYR9!s  
{ =N62 ){{  
return sFilePath; 9vQI ~rz?  
} Y]xFe>  
y@#JzfY?Hr  
%j.B/U$  
public void setSFilePath(String value) #%~PNki  
{ (R.l{(A  
sFilePath = value; o =oXL2}  
} S,ENbP%0r  
|XDbf3^6  
E%[2NsOM]  
public String getSFileName() X]Aobtz  
{ N)kZ2|oD  
return sFileName; +f}u.T_#  
} 0tL#-47  
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public void setSFileName(String value) Qj1qx;S  
{ Jv,*rQH  
sFileName = value; ^\
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} #~_ZG% u  

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public int getNSplitter() pR3@loFQ`o  
{ >@Nn_d  
return nSplitter; m-<"`:+  
} X,]E {  
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public void setNSplitter(int nCount) 4Y2!q$}I+  
{ 8|z@"b l)  
nSplitter = nCount; lU
`}  
} H%peE9
>$  
} !Ojf9 6is  
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/* !OCb^y  
**Utility.java \CY_nn|&g  
*/ ujLz<5gKuO  
package NetFox; 7f$ hg8  
8wi2&j_  

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public class Utility { \y
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public Utility() LX!MDZz  
{ QY^v*+lr\  
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} 6E
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,\DSi&T  
//线程睡眠 7)i6L'r  
public static void sleep(int nSecond) #:)yh]MP  
{ pX/42W  
try{ )y .1}R2[  
Thread.sleep(nSecond); 7m<;"e)  
} tO@n3"O  
catch(Exception e) a3Fe42G2c|  
{ $Lc-}m9n  
e.printStackTrace (); ImG7E w  
} .szc
-r{  
}
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9R1S20O  
//日志 u&npUw^Va  
public static void log(String sMsg) ,K-?M5(n9  
{ B7u4e8(E*  
System.err.println(sMsg); kWKAtv5@w  
} K]Rb~+a<  
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Z{ AF8r  
public static void log(int sMsg) "Xz[|Xl  
{ b-"kcl
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System.err.println(sMsg); mR1|8H!f  
} EqjaD/6Y`  
} 3m]8>1e
1"  
*@-a{T}  
d>YX18'<Q  
/* px~:'U  
**TestMethod.java .}4^b\  
*/ lI&5.,2MP  
package NetFox; ro8c-[V  
;&~9k?v7L  
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public class TestMethod { z"PU`v  
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public TestMethod() 9u^yEqG`  
{ ///xx/weblogic60b2_win.exe Y *?hA'  
try{ FDQP|,  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); w dpd`  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); F=9
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SiteFileFetch fileFetch = new SiteFileFetch(bean); rJ^*8C!  
fileFetch.start(); 7+c}D>/`:  
} EjjW%"C,  
catch(Exception e){e.printStackTrace ();} 1(4}rB3  
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} zAA3bgaa  
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public static void main(String[] args) &XF@Dvv  
{ e'MLLC[  
new TestMethod(); OY'6~w9  
} 37U$9]  
} .EXxNB]%Y&  
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