http断点续传简单实现（java)

/* PrEfJ?  
**SiteFileFetch.java "4QD\k5  
*/ Bnd Y\  
package NetFox; $olITe"$g  
import java.io.*; XV<{tqa  
import java.net.*; .t%`"C  
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public class SiteFileFetch extends Thread { N07FU\<9  
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SiteInfoBean siteInfoBean = null; //文件信息Bean + gP 4MP  
long[] nStartPos; //开始位置 [/eRc  
long[] nEndPos; //结束位置 mr#XN&e  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 _dw6 C2]P  
long nFileLength; //文件长度 
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boolean bFirst = true; //是否第一次取文件 vM/D7YS:  
boolean bStop = false; //停止标志 %VzCeS9  
File tmpFile; //文件下载的临时信息 ^sZ,(sc{G  
DataOutputStream output; //输出到文件的输出流 ]`n6H[6O  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） .Vb\f  
public SiteFileFetch(SiteInfoBean bean) throws IOException 2sqNTuO6,|  
{ Ru^j~Cj5  
siteInfoBean = bean; Z^vcODeC$  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); dpcFS0  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); VZ$FTM^b8  
if(tmpFile.exists ()) `Ot;KDz  
{ #Q_ d  
bFirst = false; E6y ?DXWH  
read_nPos(); UZRCJ  
} R4g% $}  
else g_t1(g*s  
{ #1` lJ  
nStartPos = new long[bean.getNSplitter()]; 92K#xM/  
nEndPos = new long[bean.getNSplitter()]; sa>}wz<o  
} i\u m;\  
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} /MQI5Djg  
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public void run() ZI'Mr:z4  
{ j?rq%rQd  
//获得文件长度 ^l"  
//分割文件 ir*T,O 2J  
//实例FileSplitterFetch 8 m T..23  
//启动FileSplitterFetch线程 v"dj%75O?e  
//等待子线程返回 89{@2TXR
 
try{ g` QbJ61a  
if(bFirst) #=B~} _  
{ /_G^d1T1?L  
nFileLength = getFileSize(); hhVyz{u  
if(nFileLength == -1) tv1Z%Mx?Cp  
{ 5
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System.err.println("File Length is not known!"); ")87GQ(R  
} Q
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else if(nFileLength == -2) 7Ed6o  
{ -K K)}I`  
System.err.println("File is not access!"); :b_R1ZV|  
} _jW}p-j  
else \D37l_  
{ DxLN{
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for(int i=0;i<nStartPos.length;i++) ITu6m<V  
{ _XqD3?yH4  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); bQ"w%!  
} g0!{CW  
for(int i=0;i<nEndPos.length-1;i++) 'v"{frh  
{ /J"U`/ {4  
nEndPos = nStartPos[i+1]; J c~{ E  
} }I\hOL
 
nEndPos[nEndPos.length-1] = nFileLength; q! +?  
} mGmkeD'  
} J\@yP  
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//启动子线程 b'N(eka  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; K)AJx"  
for(int i=0;i<nStartPos.length;i++) 'o#ve72z1  
{ #*[G,s#t^  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), tp,e:4\8Q  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), _[,oP s:+  
nStartPos,nEndPos,i); 8yH*  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8tM40/U$  
fileSplitterFetch.start(); ;MqH)M  
} ",\,lqV  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), fBptjt_  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); XujVOf  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ~ l'dpg  
nEndPos = " + nFileLength); k{op,n#  
// fileSplitterFetch[nPos.length-1].start(); `2X#;{a:  
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//等待子线程结束 =U6%Wdth  
//int count = 0; g9fS|T  
//是否结束while循环 $ePBw~yu  
boolean breakWhile = false; G &'eP  
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while(!bStop) K0#kW \4`  
{ @iZ"I i&+  
write_nPos(); 0ivlKe%  
Utility.sleep(500); BTXS+mvl  
breakWhile = true; ?qeBgkL(B^  
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for(int i=0;i<nStartPos.length;i++) P&@:''  
{ tdTD!'  
if(!fileSplitterFetch.bDownOver) ;* vVucx  
{ -uDB#?q:W  
breakWhile = false; a}Db9=  
break; }E5oa\1u  
} SCClD6k=V  
} gW
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if(breakWhile) _`>F>aP  
break; Th&* d;  
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//count++; LFsrqdzJ  
//if(count>4) 6~KtT{MYQ  
// siteStop(); c?qg i"kS  
} fUh7PF%
 
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System.err.println("文件下载结束！"); *xEcX6ZHX  
} ;\@co5.=  
catch(Exception e){e.printStackTrace ();} m_Owe/BC#m  
} HH>"J/;c,  
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//获得文件长度 Y}_J@&:  
public long getFileSize() EG<YxNX,  
{ :`
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int nFileLength = -1; [|ghq  
try{ Ys@M1o  
URL url = new URL(siteInfoBean.getSSiteURL()); 0n25{N  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ?*i qg[:  
httpConnection.setRequestProperty("User-Agent","NetFox"); cd8~y  
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int responseCode=httpConnection.getResponseCode(); *B7+rd  
if(responseCode>=400) KX e/i~A
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{ .\kcWeC\  
processErrorCode(responseCode); 8}m bfuo1  
return -2; //-2 represent access is error 49%qBO$R  
} t?NB#/#%x  
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String sHeader; HC0q_%j  
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for(int i=1;;i++) Si,[7um  
{ OR[6pr@  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); N&`VMEB)k  
//Utility.log(in.readLine()); @5n!t1(  
sHeader=httpConnection.getHeaderFieldKey(i); lv_|ws  
if(sHeader!=null) ,?Pn-aC+  
{ %T]NM3|U  
if(sHeader.equals("Content-Length")) Ekx3GM_]  
{ )clSW  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); bWzv7#dd=  
break; FLI\SF<  
} 7cx~?xk <m  
} |zD{]y?S-  
else -%]O-'  
break; 8'Dp3x^W>  
} 0HUSN_3F  
}  laX(?{_  
catch(IOException e){e.printStackTrace ();} 2j_YHv$I  
catch(Exception e){e.printStackTrace ();} [%(}e1T(  
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Utility.log(nFileLength); +TW9BU'a^  
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return nFileLength; Ju3-ZFUS4  
} Bq~!_6fB  
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//保存下载信息（文件指针位置） 7.fpGzUM  
private void write_nPos() *<k8H5z8]  
{ .'o<.\R8  
try{ 70NQ9*AAy  
output = new DataOutputStream(new FileOutputStream(tmpFile)); T'9I&h%\  
output.writeInt(nStartPos.length); <ijf':X=*  
for(int i=0;i<nStartPos.length;i++) `n%uvo}UT  
{ `]^0lD=eI  
// output.writeLong(nPos); [:gPp)f,  
output.writeLong(fileSplitterFetch.nStartPos); Qs2E>C  
output.writeLong(fileSplitterFetch.nEndPos); ,bT|:T@ny  
} 7%?2>t3~  
output.close(); Wz)O,X^  
} VXt8y)?a  
catch(IOException e){e.printStackTrace ();} 9"m
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catch(Exception e){e.printStackTrace ();} C"bG?Mb  
} )1Rn;(j9Re  
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//读取保存的下载信息（文件指针位置） IC&xL
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private void read_nPos() / fBi9=}+  
{ Oo'IeXQ9(  
try{ tpe:]T/xh  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); utIR\e#:B  
int nCount = input.readInt(); Cz=HxU80J  
nStartPos = new long[nCount]; _@I8B  
nEndPos = new long[nCount]; C/Vs+aW n  
for(int i=0;i<nStartPos.length;i++) XWH{+c"  
{ 06@^knm  
nStartPos = input.readLong(); noY~fq/U  
nEndPos = input.readLong(); _ndc^OG  
} e?W-vi%  
input.close(); eELJDSd BV  
} H/8H`9S$  
catch(IOException e){e.printStackTrace ();} Jt79M(Hp!  
catch(Exception e){e.printStackTrace ();} \lj.vzD-A  
} '6l4MR$j&m  
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private void processErrorCode(int nErrorCode) 3WdYDv]N}L  
{ t)|*-=  
System.err.println("Error Code : " + nErrorCode); ,&>LBdG`  
} @<]sW*s  
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//停止文件下载 AF ,*bb  
public void siteStop() sT.;*3{  
{ (,Zy2wr=  
bStop = true; 4DhG
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for(int i=0;i<nStartPos.length;i++) N ]
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fileSplitterFetch.splitterStop(); /Y=Cg%+  
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} ;Du+C%  
} p,_,o3@~  
//负责部分文件的抓取 WZz8VF  
**FileSplitterFetch.java USF9sF0l  
*/ [ j'L*j  
package NetFox; ~s.~X5  
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import java.io.*; Z) nB  
import java.net.*; +tsF.Is!t  
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public class FileSplitterFetch extends Thread { O~3<P3W
 
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String sURL; //File URL X[' VZz7  
long nStartPos; //File Snippet Start Position ,1xX`:  
long nEndPos; //File Snippet End Position )OjTn"  
int nThreadID; //Thread's ID :bBLP7eyV  
boolean bDownOver = false; //Downing is over M%(B6};J  
boolean bStop = false; //Stop identical R]dN-'U  
FileAccessI fileAccessI = null; //File Access interface NC]]`O2r@  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException L7kNQ/  
{ e}@VR<h  
this.sURL = sURL; Ej_>*^b  
this.nStartPos = nStart; '6^+|1  
this.nEndPos = nEnd; 6JrwPZB  
nThreadID = id; |nOqy&B  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 @;\2 PD  
} U-F\3a;&  
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public void run() r4YiXss  
{ QoLp$1O(y  
while(nStartPos < nEndPos && !bStop) -|z ]Ir  
{ Bf5Z  
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try{ q fc:%ks2  
URL url = new URL(sURL); 7pllzy  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |Do+=Gr$t@  
httpConnection.setRequestProperty("User-Agent","NetFox"); LDDgg u   
String sProperty = "bytes="+nStartPos+"-"; z6IOVQ*r  
httpConnection.setRequestProperty("RANGE",sProperty); >-&B#Z^,  
Utility.log(sProperty); _+sb~  
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InputStream input = httpConnection.getInputStream(); G_m$?0\  
//logResponseHead(httpConnection); W)X" G3  
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byte[] b = new byte[1024]; -R]Iu\  
int nRead; %`EyG  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) `e`}dgf0S|  
{ ^l:~r2  
nStartPos += fileAccessI.write(b,0,nRead); I`~Giz7@  
//if(nThreadID == 1) c>|1%}"?  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @$Xl*WT7  
} 'iM#iA8  
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Utility.log("Thread " + nThreadID + " is over!"); FNN7[ku!  
bDownOver = true; QkFB\v  
//nPos = fileAccessI.write (b,0,nRead); &%UZ"CcA  
} {xD\w^  
catch(Exception e){e.printStackTrace ();} 5gq  
} &ir|2"HV  
} }>5R9  
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//打印回应的头信息 `@<~VWe5  
public void logResponseHead(HttpURLConnection con) n2(`O^yd7C  
{ %A3ci[$g  
for(int i=1;;i++) $$ 9!4  
{ ?NVX# t'  
String header=con.getHeaderFieldKey(i); >"q?P^f/  
if(header!=null) o5E5s9n  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); yMz dM&a!*  
Utility.log(header+" : "+con.getHeaderField(header)); b$
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else ^, &'  
break; !C&  ^%a  
} H %Dcp#k  
} i*]$_\yl"  
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public void splitterStop() =o)B1(v@.  
{ :anR/  
bStop = true; ri2`M\;gt  
} rw$ =!iyO  
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} 35H.ZXQp-  
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/* m++=FsiX=  
**FileAccess.java !{?<(6;t  
*//文件访问(定位，写) #Ibpf ,  
package NetFox;  \62!{  
import java.io.*; Y6`^E  
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public class FileAccessI implements Serializable{ 48,uO!  
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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 eGLB,29g
 
RandomAccessFile oSavedFile; F@b=S0}K  
long nPos; @e-2]z  
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public FileAccessI() throws IOException y q!{\@-  
{ Ki>XLX,er=  
this("",0); *mz-g7  
} ]wUH*\(y  
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public FileAccessI(String sName,long nPos) throws IOException %R<xe.X  
{ 9/=+2SZ  
oSavedFile = new RandomAccessFile(sName,"rw"); RgVnx]IF  
this.nPos = nPos; ><qA+/4]_  
oSavedFile.seek(nPos); .;)V;!   
} oS~;>]W  
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public synchronized int write(byte[] b,int nStart,int nLen) lMgPwvs'  
{ 6
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int n = -1; lV9  
try{ iikMz|:7U  
oSavedFile.write(b,nStart,nLen); lHFk~Qp[  
n = nLen; <b?$-Rx  
} t)mc~M9w  
catch(IOException e) /i{V21(%  
{ aK8s0G!z?5  
e.printStackTrace (); U_RWqK
L  
} iqFC~].)  
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return n;

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} 6m@B.+1  
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} V{fG~19  
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/* vnS8N  
**SiteInfoBean.java L4ZB0PmN'  
*/ ^b4i9n,t1  
package NetFox; !Sl_qL  
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public class SiteInfoBean { z0%tBgqY(  
ay#f\P!1  
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private String sSiteURL; //Site's URL c& K`t  
private String sFilePath; //Saved File's Path =G !]_d0  
private String sFileName; //Saved File's Name r`pf%9k  
private int nSplitter; //Count of Splited Downloading File _h
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public SiteInfoBean() L2wX?NA  
{//nSplitter的缺省值为5 >WLHw!I!6  
//default value of nSplitter is 5 D G|v'#  
this("","","",5); "xnULQK  
} )Cat$)I#,  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) .Hk.'>YR  
{ @>8{J6%\  
sSiteURL= sURL; 0M?zotv0#  
sFilePath = sPath; Xtloyph  
sFileName = sName; 64vj6 &L  
this.nSplitter = nSpiltter; IfT: 9 &  
]re}EB\Rs  
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} @}Q!K*  
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public String getSSiteURL() 5m;BL+>YE  
{ G_zK .N  
return sSiteURL; 3sW!ya-VZ  
} nwzyL`kF  
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public void setSSiteURL(String value) bAy\Sr #/  
{ '4,IGxIq  
sSiteURL = value;  FsQoQ#*  
} e{3%-  
kB%.i%9\\  
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public String getSFilePath() LFZ*mRiuKE  
{ n&DBMU  
return sFilePath; ;lSsy  
} r'lANl-v  
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public void setSFilePath(String value) Z@%A(nZ_  
{ _%23L|
 
sFilePath = value; j(}pUV B  
} Z9*@w`x^u  
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public String getSFileName() ,?HM5c{'[Y  
{ {oR@'^N  
return sFileName; Y9&na&vY?  
} Bk^o$3#  
[LUqF?K&  
rl&.|;5uH;  
public void setSFileName(String value) B !wr}]  
{ #{^qBP
[  
sFileName = value; b'z\|jY  
} t* p%!xsH  
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HgBu:x?&  
public int getNSplitter() |[>yJXxEL@  
{ xI/8[JW*  
return nSplitter; 9\T9pjdZE  
} 2-Wy@\  
}' sW[?ik  
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public void setNSplitter(int nCount) K5t.
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{ lV$#>2Hh5  
nSplitter = nCount; y~\uS  
} pYu6[  
} $<Y%4LI  
>3&V"^r(|  
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/* D*?LcxX  
**Utility.java pn){v  
*/ u8`S*i/)m  
package NetFox; & 9 c^9<F  
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public class Utility { m|t\w|B2  
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public Utility() q">}3`
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{ /L@6Ae  
%6m' |(-  
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} Ap;^\5  
Y6v#0pT  
//线程睡眠 IiE^HgM  
public static void sleep(int nSecond) W:6#0b"_#  
{ T!HAE#xC  
try{ V@TA~'$|  
Thread.sleep(nSecond); z"QXPIXPk  
} oDJ &{N|  
catch(Exception e) &^uaoB0  
{ 7,V_5M;t  
e.printStackTrace (); C8)Paop$  
} Wm5[+z|2?9  
} >!{8)ti  
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//日志 d6
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public static void log(String sMsg) ;l `Ufx  
{ Y9vVi]4  
System.err.println(sMsg); +aPe)U<t  
} 1 XJZuv,T:  
#o9CC)q5G  
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public static void log(int sMsg) /BvMNKb$$  
{ 5 wN)N~JE  
System.err.println(sMsg); rd$T6!I  
} 6Yt3Oq<U  
} aG4 ^xOD  
<w8H[y"c  
I,,SR"  
/* z7)$m0',?  
**TestMethod.java hNgT/y8  
*/ C=U4z|Ym  
package NetFox; WX_g  
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public class TestMethod {
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K V?+9qa,  
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public TestMethod() gSyBoY  
{ ///xx/weblogic60b2_win.exe /Dt:4{aTOC  
try{ '"rm66  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); -49I3&  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); C#1'kQO  
SiteFileFetch fileFetch = new SiteFileFetch(bean); xS+xUi  
fileFetch.start(); TeR
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} O*,O]Q  
catch(Exception e){e.printStackTrace ();} :P+7ti@  
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} _+7P"B|\  
:J2^Y4l2  
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public static void main(String[] args) Ah5o>ZtcO  
{ ?6x&A t  
new TestMethod(); 5xNOIOpDB  
} cd=H4:<T5  
} 0QrRG$<4X  
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