http断点续传简单实现（java)

/* Bal e_s^  
**SiteFileFetch.java at4JLbk  
*/ &,yF{9$G  
package NetFox; h3-^RE5\`S  
import java.io.*; -+Ot'^  
import java.net.*; tDRo)z  
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public class SiteFileFetch extends Thread { A*~G[KC3(  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ul#y'iY]  
long[] nStartPos; //开始位置 +80bG(I_  
long[] nEndPos; //结束位置 ;0Q" [[J  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ,n[<[tkCR  
long nFileLength; //文件长度 *5.wwV  
boolean bFirst = true; //是否第一次取文件 1y\bJ  
boolean bStop = false; //停止标志 3&CV!+z  
File tmpFile; //文件下载的临时信息 OTE,OCB[  
DataOutputStream output; //输出到文件的输出流 :P/VBX
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） zyhM*eM.7  
public SiteFileFetch(SiteInfoBean bean) throws IOException ]
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{ >KL=(3:":p  
siteInfoBean = bean; Hqs!L`oW)  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); BGxwPJd  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ~^jPE)  
if(tmpFile.exists ()) K1^7v}P  
{ w^Yo)"6  
bFirst = false; Vjs'|%P7  
read_nPos(); {kw%7}!  
} ~\<$H'  
else }I-nT!D'y  
{ 3}!u8,P  
nStartPos = new long[bean.getNSplitter()]; "w%:5~u9  
nEndPos = new long[bean.getNSplitter()]; pS|K[:5  
} ;N?(R\*8  
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} !^&VZh
  
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public void run() 3>^]r jFw  
{ Y!_{:2H8p  
//获得文件长度 PPH;'!>s"  
//分割文件 ch:rAx  
//实例FileSplitterFetch Sc
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//启动FileSplitterFetch线程 u*): D~A  
//等待子线程返回 W#~7X  
try{
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if(bFirst) h x&"fe  
{ )v_v 7 ~H&  
nFileLength = getFileSize(); ,}&TZkN{-  
if(nFileLength == -1) %4),P(4N  
{ YI ?P@y  
System.err.println("File Length is not known!"); eA86~M?<o  
} Rx&O}>"E>l  
else if(nFileLength == -2) Er%&y  
{ Y(bB7tR  
System.err.println("File is not access!"); r'j88)^  
} ij;NM:|Sd  
else \fUX_0k9,  
{ z4Zm%  
for(int i=0;i<nStartPos.length;i++) n0T|U
 
{ S4`X^a}pY  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ` P
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} 8T9s:/%  
for(int i=0;i<nEndPos.length-1;i++) .Y{x!Q"  
{ v:/\;2  
nEndPos = nStartPos[i+1]; \Q(a`6U  
} Lv]%P.=[G  
nEndPos[nEndPos.length-1] = nFileLength; "A"YgD#t  
} 7)V"E-6h  
} 'I&0$
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//启动子线程 w(&EZDe  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; On}1&!{1]  
for(int i=0;i<nStartPos.length;i++) n 5R9<A^  
{ 8 E\zjT!#\  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), I2WP/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 'z5jnI  
nStartPos,nEndPos,i); O^`EuaL  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 0S$k;q  
fileSplitterFetch.start(); (&Rk#iU 2  
} NGSts\D'}  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), t&?{+?p: 9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); /]3[|  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", QR#>Ws  
nEndPos = " + nFileLength); K~vJ/9"|R  
// fileSplitterFetch[nPos.length-1].start(); t_jn-Idcf  
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//等待子线程结束 FHQ`T\fC$@  
//int count = 0; Au'y(KB  
//是否结束while循环 %rG4X  
boolean breakWhile = false; cyJ{AS+  
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while(!bStop) d-B+s%>D  
{ ?-<lIFFh  
write_nPos(); m%`YAD@2z  
Utility.sleep(500); jeWv~JA%L|  
breakWhile = true; f(w>(1&/B  
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for(int i=0;i<nStartPos.length;i++) ;,[0bmL  
{ v#qdq!64  
if(!fileSplitterFetch.bDownOver) )1 T2u  
{ ]}!@'+=  
breakWhile = false; iVn4eLK^v  
break; JkJ @bh Eu  
} ")Not$8  
} |T""v_q  
if(breakWhile) 'JMW.;Lh?X  
break; yO1 7C  
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//count++; ~dr,;NhOLJ  
//if(count>4) o@zx
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// siteStop(); :TU|:2+  
} ZQE1]ht  
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System.err.println("文件下载结束！"); \uOM,98xS  
} uVn"L:_  
catch(Exception e){e.printStackTrace ();} Ahwi  
} RH;ulAD6(~  
\s&Mz;:  
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//获得文件长度 d=xjLbsZ  
public long getFileSize() ^7spXfSAd  
{ a{T.U-0   
int nFileLength = -1; 7x6M]1F  
try{ adP :{j  
URL url = new URL(siteInfoBean.getSSiteURL()); Lmte ~oBi  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); mp
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httpConnection.setRequestProperty("User-Agent","NetFox"); 88osWo6r
G  
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int responseCode=httpConnection.getResponseCode(); i7.8H*z'  
if(responseCode>=400) (NvjX})eh  
{ T"z<D+pN  
processErrorCode(responseCode); Jr
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return -2; //-2 represent access is error ;bB#Pg  
} }CBQdH&g;  
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String sHeader; "V>}-G&  
!
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for(int i=1;;i++) 1p.c6[9-  
{ ~-zTY&c_  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); le'RU1k  
//Utility.log(in.readLine()); RJWO h  
sHeader=httpConnection.getHeaderFieldKey(i); w1)TnGT  
if(sHeader!=null) 2
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{ 
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if(sHeader.equals("Content-Length")) X 61|:E  
{ ;98&5X\u<  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); [nO3%7t@  
break; $K^l=X  
} L?[m$l!T}  
} o%?)};o  
else @-)?uYw:r  
break; ^y/Es2A#t  
} {1Ra|,;  
} (+|+ELfqW  
catch(IOException e){e.printStackTrace ();} ?@G s7'  
catch(Exception e){e.printStackTrace ();} uslu-|b!%  
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Utility.log(nFileLength); <YU?1y?V  
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return nFileLength; 2o?j{K  
} oPmz$]_Z  
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//保存下载信息（文件指针位置） WoZU} T-  
private void write_nPos() uy hh"[  
{ {1SsHir>  
try{ hU$o^ICH  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 0zH-g  
output.writeInt(nStartPos.length); F\DiT|?}  
for(int i=0;i<nStartPos.length;i++) X hq ss),  
{ @Y/&qpo$#W  
// output.writeLong(nPos); C1D:Xi-  
output.writeLong(fileSplitterFetch.nStartPos); \V$qAfP)  
output.writeLong(fileSplitterFetch.nEndPos); 3*h"B$g!  
} Z<.&fZ^jS  
output.close(); ]:gW+6w"C  
} &4-;;h\H  
catch(IOException e){e.printStackTrace ();} x &R9m,  
catch(Exception e){e.printStackTrace ();} `> %QCc\  
} gE6'A  
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//读取保存的下载信息（文件指针位置） w7@`:W  
private void read_nPos() N#ggT9>X  
{ FLWVI4*  
try{ gQPw+0w  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); QJ XP-  
int nCount = input.readInt(); <<0sv9qw1  
nStartPos = new long[nCount]; \\k=N(n  
nEndPos = new long[nCount]; +Hu\b&g  
for(int i=0;i<nStartPos.length;i++) ,\6Vb*G|E>  
{ t<UJR*R=L  
nStartPos = input.readLong(); V?M(exN  
nEndPos = input.readLong(); uY.Ns ?8  
} A08kwYxiW  
input.close(); G(7%*@SX  
} iO$87!  
catch(IOException e){e.printStackTrace ();} ~M}{rl.n=  
catch(Exception e){e.printStackTrace ();} lOt7ij(,L  
} =Dq&lm,n  
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private void processErrorCode(int nErrorCode) 76tn`4NIP  
{ eUy*
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System.err.println("Error Code : " + nErrorCode); %R>n5m  
} 1Vu#:6%  
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/JS_gr@DK  
//停止文件下载 .P1WY  
public void siteStop() 9ngxkOGx  
{ 3=d%WPgQ  
bStop = true; 3&y-xZu]  
for(int i=0;i<nStartPos.length;i++) AXlV
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fileSplitterFetch.splitterStop(); S~3|1Hw*tN  
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} <L]Gk]k_R  
} KUJLx  
//负责部分文件的抓取 (F&LN!Hn>p  
**FileSplitterFetch.java b=5w>*  
*/
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package NetFox; ]Kt@F0U<o  
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import java.io.*; q}t]lD %C  
import java.net.*; @:?[R&`  
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public class FileSplitterFetch extends Thread { }i8y/CA  
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String sURL; //File URL k;^$Pd?t  
long nStartPos; //File Snippet Start Position z6R|1L 1  
long nEndPos; //File Snippet End Position p-iFe\+  
int nThreadID; //Thread's ID _{jC?rzb  
boolean bDownOver = false; //Downing is over Q$U5[
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boolean bStop = false; //Stop identical (X "J)xaQ  
FileAccessI fileAccessI = null; //File Access interface hP)Zm%@0f  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException F%6wdM W  
{ DC h !Z{I  
this.sURL = sURL; 6bPxEILm  
this.nStartPos = nStart; tpGT~Y(  
this.nEndPos = nEnd; ye.6tlW  
nThreadID = id; oks;G([  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 W_}j~[&  
} I(*3n"  
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public void run() 5f7id7SI  
{ ^t})T*hM0  
while(nStartPos < nEndPos && !bStop) 4H6Fq*W{k
 
{ M[`[+5v  
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try{ A1prYD  
URL url = new URL(sURL); s6~;)(r  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); a>OYJe  
httpConnection.setRequestProperty("User-Agent","NetFox");  4v`
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String sProperty = "bytes="+nStartPos+"-"; xS1|t};  
httpConnection.setRequestProperty("RANGE",sProperty); Odo)h  
Utility.log(sProperty);  @*eY~  
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InputStream input = httpConnection.getInputStream(); tBGL
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//logResponseHead(httpConnection); &za }THm  
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byte[] b = new byte[1024]; ,,uhEoH  
int nRead; ;8^k=8  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) s>/Xb2\  
{ {g.YGO  
nStartPos += fileAccessI.write(b,0,nRead); c0zcR)=mL  
//if(nThreadID == 1) (c[u_~ ;  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); TX=894{nGh  
} lMFo)4&P  
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Utility.log("Thread " + nThreadID + " is over!"); S=,czs3N  
bDownOver = true; l6bY!I>  
//nPos = fileAccessI.write (b,0,nRead); 1gV?}'jq  
} 3*<@PXpK&  
catch(Exception e){e.printStackTrace ();} \1Y|$:T/  
} kf'(u..G  
} ^y@ W\  
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//打印回应的头信息 Ef`'r))  
public void logResponseHead(HttpURLConnection con) B{)#A?Rh.  
{ >T]9.`xhK  
for(int i=1;;i++) DP),~8  
{ X:UlL"G  
String header=con.getHeaderFieldKey(i); &9flNoNR9  
if(header!=null) th73eC'  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ^W$R{`  
Utility.log(header+" : "+con.getHeaderField(header)); x6,ozun  
else >1`4]%  
break; |~5cNm  
} TBt5Nqks-  
} GM2}]9  
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public void splitterStop() {Phq39g  
{ 2VY7?1Ab(@  
bStop = true; :
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} }B'-*)^|e{  
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} [ iTP:8  
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/* G{[w+ObX  
**FileAccess.java d3q%[[@  
*//文件访问(定位，写) xmnBG4,f  
package NetFox; <<01@Q <  
import java.io.*; Zy+ERaF|]  
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public class FileAccessI implements Serializable{ B6dU6"  
!-`L1D_hy  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 %w^*7Oi  
RandomAccessFile oSavedFile; A{s-
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long nPos; t[TM\j0jW  
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public FileAccessI() throws IOException 4wSZ'RTSR  
{ _S{TjGZ&  
this("",0); oW^x=pS9  
} CaZc{  
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public FileAccessI(String sName,long nPos) throws IOException #;!@Pf  
{ "BT M,CB  
oSavedFile = new RandomAccessFile(sName,"rw"); z" tz-~  
this.nPos = nPos; h)Fc<,vwBE  
oSavedFile.seek(nPos); BX$<5S@  
} "9P @bA  
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public synchronized int write(byte[] b,int nStart,int nLen) \'Ca1[y@B  
{ sAc1t`  
int n = -1; R*pPUw\yn  
try{ kFE9}0-  
oSavedFile.write(b,nStart,nLen); *{VC<<`  
n = nLen; cRs.@U\{R\  
} </;e$fh`  
catch(IOException e) .hH_1Mo
8  
{ l1T`[2  
e.printStackTrace (); Z$J-4KN  
} 4}DFCF%B  
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return n; {x
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} /%;J1{O  
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} bXJ(QXHd%  
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5 <k)tF%  
/* w\i]z1  
**SiteInfoBean.java U3_O}X+  
*/ *eH
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package NetFox; |?J57(  
<B>qEa_I  
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public class SiteInfoBean { FNUs .d"  
%P~;>4i,  
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private String sSiteURL; //Site's URL d,?D '/  
private String sFilePath; //Saved File's Path )A*53>JV  
private String sFileName; //Saved File's Name c<Cf|W  
private int nSplitter; //Count of Splited Downloading File p^ (Z  
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public SiteInfoBean() +JYb)rn$^  
{//nSplitter的缺省值为5 t
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//default value of nSplitter is 5 "y~*1kBu  
this("","","",5); ^Lb\k|U,\  
} 2'=)ese  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) .'o=J`|  
{ Eb~vNdPo  
sSiteURL= sURL; xGyl7$J  
sFilePath = sPath; *bo| F%NAz  
sFileName = sName; kttJTP77t  
this.nSplitter = nSpiltter; {Y5@SIyE  
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} mC@v,"  
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public String getSSiteURL() :ILpf+`yY  
{ (hOD  
return sSiteURL; Il4]1d|  
} MOh&1]2j5  
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public void setSSiteURL(String value) muXP5MO  
{ c

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sSiteURL = value; >}f!. i  
} o]tfvGvU*  
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public String getSFilePath() ##''d||u  
{ ZRYlm$C  
return sFilePath; YGPb8!  
} Zgh~7Z/  
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public void setSFilePath(String value) p4IyKry,  
{ @{RhO|UR  
sFilePath = value; Y$XzZ>VW  
} ::{\O\w  
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JtY$AP$  
public String getSFileName() o|d:rp!^  
{ ~q+AAWL  
return sFileName; DcFYb|p  
}
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public void setSFileName(String value) 6<@+J  
{ 9c4p9b!  
sFileName = value; >lM/\HO2  
} {hN\=_6*EW  
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public int getNSplitter() b=S"o )>  
{ u
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return nSplitter; Y*pXbztP  
} V?*fl^f  
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public void setNSplitter(int nCount) z[ ;n2o|s  
{ nLAwo3  
nSplitter = nCount; [4C_iaE  
} 2k=|p@V n~  
} Has}oe[  
^L.I9a#]  
6oQ7u90z*  
/* y`$qcEw  
**Utility.java 'LG\]h>+)  
*/ sF)$<[w
 
package NetFox; IAkQR0fcN  
#tUhul/O  
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public class Utility { `qd5+~c  
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public Utility() 7hx^U90K  
{ F$4=7Njv  
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} +%[, m&  
FTEC=j$ln  
//线程睡眠 /g*_d
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public static void sleep(int nSecond) Ux?G:LLz  
{ D1deh=  
try{ ?>ZrdfTwz,  
Thread.sleep(nSecond); 7>@0nHec  
} 20$Tky_  
catch(Exception e) c]VK%zl  
{ 9wc\~5{li  
e.printStackTrace (); a'-xCV|^  
} xS/=9l/G  
} m,hqq%qz  
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//日志 JcP<@bb>B  
public static void log(String sMsg)  HL[V}m  
{ S.iUiS"  
System.err.println(sMsg); `ba<eT':  
} hiVDN"$$  
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public static void log(int sMsg) t3}_mJ  
{ 
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System.err.println(sMsg); liB~vdqj  
} >d .
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} 3- d"-'k  
cbou1Ei   
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/* @:'E9J06  
**TestMethod.java KVoi>?a   
*/ R. ryy  
package NetFox; b0%#=KMi  
}EfRYE$E  
;SA+
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public class TestMethod { '@hnqcqXq  
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7S&O{Q7)  
public TestMethod() R*dXbI&,e  
{ ///xx/weblogic60b2_win.exe Ax!@vL&@  
try{ TxkvHiq2  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); I[ZWOi\- ;  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); hoPh#? G  
SiteFileFetch fileFetch = new SiteFileFetch(bean); .b*-GWx  
fileFetch.start(); JKXIxw>q  
} L(`q3>iC4.  
catch(Exception e){e.printStackTrace ();} 6NFLk+kqN  
2I4G=jM[  
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} %HZ!s `w_  
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public static void main(String[] args) l_q1h]/   
{ jI}{0LW&F&  
new TestMethod(); N~yGtnW  
} #zd}xla0]  
} *i7-_pT  
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