http断点续传简单实现（java)

/* jw]IpGTt  
**SiteFileFetch.java ,=P0rbtK  
*/ YC}$O2  
package NetFox; v=H!Y";  
import java.io.*; 8
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import java.net.*; CzT_$v_  
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public class SiteFileFetch extends Thread { &J=x[{R  
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SiteInfoBean siteInfoBean = null; //文件信息Bean b$FXRR\G  
long[] nStartPos; //开始位置 F,XJGD*  
long[] nEndPos; //结束位置 9a.[>4}  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 td+[Na0d  
long nFileLength; //文件长度 1z[blNs&  
boolean bFirst = true; //是否第一次取文件 4_S%K&  
boolean bStop = false; //停止标志 Zn'y"@%t[  
File tmpFile; //文件下载的临时信息 T0}P 'q  
DataOutputStream output; //输出到文件的输出流 ~0n9In%  
!
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ::8E?c  
public SiteFileFetch(SiteInfoBean bean) throws IOException CY9`HQ1  
{ Fw;Y)y=O  
siteInfoBean = bean; ..^,*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); k_Edug~B  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); dk2o>jI4;  
if(tmpFile.exists ()) ?/s=E+  
{ #/pZ#ny  
bFirst = false; II_MY#0X  
read_nPos(); Ia)
^  
} KL*UU,qU  
else k?=V?JWY
 
{ Iyvl6  
nStartPos = new long[bean.getNSplitter()]; SHPZXJ{  
nEndPos = new long[bean.getNSplitter()]; \'N|1!EO|t  
} Bb/aeLv  
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} BcoE&I?[m|  
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public void run() ~LzTqMHM  
{ G,i%:my7  
//获得文件长度 gM3gc;  
//分割文件 LvS3c9|Aj  
//实例FileSplitterFetch =;xlmndT,  
//启动FileSplitterFetch线程 ; bDFrG  
//等待子线程返回 /7zy5  
try{ x]U (EX`t$  
if(bFirst) kLqFh<  
{ Ljxn}):[  
nFileLength = getFileSize(); Sq==)$G  
if(nFileLength == -1) HM1y$ej  
{ yQ8H-a.  
System.err.println("File Length is not known!"); k .l,>s`!  
} @.i
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else if(nFileLength == -2) >heih%Ar0J  
{ z*>CP  
System.err.println("File is not access!"); cWM|COXL+  
} I@q>ES!1H  
else  g^En6n)  
{ aa1XY&G"!  
for(int i=0;i<nStartPos.length;i++) ;7<a0HZ5!  
{ j|(bDa
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); ArU>./)Q  
} BmUzsfD  
for(int i=0;i<nEndPos.length-1;i++) Xc5[d`]  
{ :<IW'  
nEndPos = nStartPos[i+1]; ikRIL2Y  
} |,&!Q$<un  
nEndPos[nEndPos.length-1] = nFileLength; RN:#+S(8  
} *id|za
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} FZmYv%J  
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//启动子线程 e
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; k*c:%vC!  
for(int i=0;i<nStartPos.length;i++) NI s4v(!  
{ @#H{nj Z  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), v981nJ>w,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 7RD` *s  
nStartPos,nEndPos,i); e?lqs,m@"  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); <p0$Q!^dK=  
fileSplitterFetch.start(); 8h20*@wSN  
}
-{b1&  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6l vx  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); @7^#_772  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", [Iihk5TT  
nEndPos = " + nFileLength); 3Yj}ra}  
// fileSplitterFetch[nPos.length-1].start(); |PJW
2PN  
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//等待子线程结束 '7*=m^pc  
//int count = 0; UXk8nH  
//是否结束while循环 }5tn  
boolean breakWhile = false; A
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while(!bStop) C aJ
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{ )#ujF~w>  
write_nPos(); Gj_b GqF8}  
Utility.sleep(500); D
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breakWhile = true; -X}R(.}x  
};!c]/,  
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for(int i=0;i<nStartPos.length;i++) NJtB;  
{ eu:_V+  
if(!fileSplitterFetch.bDownOver) ;W*$<~_  
{ E0DEFB  
breakWhile = false; eXaDx%mM  
break; Rt:PW}rFf  
} -<O:isB  
} 6~/H#8Kdn  
if(breakWhile) KnFbRhu[  
break; #EM'=Q%TO  
#129 i2  
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//count++; |B`tRq  
//if(count>4) ?GC0dN  
// siteStop(); _INUJc  
} t2SZ]|C  
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System.err.println("文件下载结束！"); 5
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} 5,((JxX$  
catch(Exception e){e.printStackTrace ();} H= y-Y_R  
} L
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//获得文件长度 dbXG?K][  
public long getFileSize() mHMej@  
{ ]1[;A$7  
int nFileLength = -1; XN0Y#l  
try{ U+i[r&{gb  
URL url = new URL(siteInfoBean.getSSiteURL()); rh l5r"%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %%>?<4t  
httpConnection.setRequestProperty("User-Agent","NetFox"); ZF/KV\Ag)  
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int responseCode=httpConnection.getResponseCode(); fytx({I .a  
if(responseCode>=400) e](=)h|  
{ ,{50zx2  
processErrorCode(responseCode); <XagkD  
return -2; //-2 represent access is error %dU}GYL_  
} /YbL{G )j}  
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7| T:TbY>  
String sHeader; i=a LC*@  

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for(int i=1;;i++) ;hvXFU  
{ ckk[n  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 7GUJ&U)J  
//Utility.log(in.readLine()); ?:nZv< x  
sHeader=httpConnection.getHeaderFieldKey(i); ;R!
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if(sHeader!=null) `IoX'|C[h  
{ zef,*dQY  
if(sHeader.equals("Content-Length")) &B4U
)  
{ w3Ohm7N[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ]>L]?Rm  
break; K5lp-F  
} F%d"gF
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} ;^*!<F%t9R  
else `Vi:r9|P  
break; NHF?73:  
} @7=D]yu  
} YM|S<  
catch(IOException e){e.printStackTrace ();} J4g;~#_19  
catch(Exception e){e.printStackTrace ();} "/fs%F  
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Utility.log(nFileLength); Q2NnpsA^6  
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return nFileLength; 3>" h*U#  
} U;GoC$b}|  
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//保存下载信息（文件指针位置） +_dYfux  
private void write_nPos() SEIu4 l$E  
{ tl5IwrF6;  
try{ '[
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output = new DataOutputStream(new FileOutputStream(tmpFile)); :gq@/COo(  
output.writeInt(nStartPos.length); yp^*TD/J  
for(int i=0;i<nStartPos.length;i++) `W n5 .V  
{ BfT,  
// output.writeLong(nPos); 88$Y-g5*  
output.writeLong(fileSplitterFetch.nStartPos); uFWgq::\  
output.writeLong(fileSplitterFetch.nEndPos); tJPRR_nZv  
} )X;cS} yp  
output.close(); )<F\IM  
} }Xi#x*-D  
catch(IOException e){e.printStackTrace ();} i_Z5SMZ  
catch(Exception e){e.printStackTrace ();} t`,IW{  
} ZD%_PgiT  
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//读取保存的下载信息（文件指针位置） X);Zm7  
private void read_nPos() &;U7/?Q  
{ ~UC/|t$  
try{ Ch9!AUiR  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); +~Ay h[V  
int nCount = input.readInt(); !u}3H
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nStartPos = new long[nCount]; J*!:ar  
nEndPos = new long[nCount]; ;-GzGDc~0  
for(int i=0;i<nStartPos.length;i++) pHB35=p28  
{ y9li<u<PF  
nStartPos = input.readLong(); Xb-c`k~_  
nEndPos = input.readLong(); A9Wqz"[  
} vfUfrk@D~  
input.close(); Gc!8v}[7J  
} s;7qNwYO  
catch(IOException e){e.printStackTrace ();} :V~*vLvR  
catch(Exception e){e.printStackTrace ();} (iOCzZ6S  
} /^3oq]  
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private void processErrorCode(int nErrorCode) 5MY}(w  
{ ;nKHm  
System.err.println("Error Code : " + nErrorCode); B8AzN9v&"N  
} SM+fG:4d  
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//停止文件下载 [Cqqjv;_  
public void siteStop() |p -R9A*>h  
{ OsL%SKs|  
bStop = true; Vnj/>e3  
for(int i=0;i<nStartPos.length;i++) *X l<aNNx  
fileSplitterFetch.splitterStop(); }FiN 7#  
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} \41)0,sEy  
} 1D
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//负责部分文件的抓取 K6{bYho  
**FileSplitterFetch.java 4ylDD|) rO  
*/ YB B$uGA  
package NetFox; G7Abhb,  
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import java.io.*; $l,Zd6<1q  
import java.net.*; CQzjCRS d  
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public class FileSplitterFetch extends Thread { #C1A5JE&  
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String sURL; //File URL )s<WG}  
long nStartPos; //File Snippet Start Position $7n#\h  
long nEndPos; //File Snippet End Position iSr`fQw#  
int nThreadID; //Thread's ID Ivt} o_b*  
boolean bDownOver = false; //Downing is over CLY6 YB' R  
boolean bStop = false; //Stop identical afF+*\xXN  
FileAccessI fileAccessI = null; //File Access interface )@bH"  
+#qt^NO  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException i<wU.JX&h  
{ B >u,)  
this.sURL = sURL; D<bU~Gd,P  
this.nStartPos = nStart; .D,?u"fk|  
this.nEndPos = nEnd; W`u$7k]$  
nThreadID = id; r*N~. tFo  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 i=1 }lkq  
} K@jSr*\'  
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public void run() |Sr\jUIWn  
{ 3 "l F  
while(nStartPos < nEndPos && !bStop) K)Zkj"y  
{ Z?(4%U5z  
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try{ o'^;tLs1
5  
URL url = new URL(sURL); WHgV_o 8  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); q)?p$\  
httpConnection.setRequestProperty("User-Agent","NetFox"); O+o;aa6  
String sProperty = "bytes="+nStartPos+"-"; 4aN+}TkH@G  
httpConnection.setRequestProperty("RANGE",sProperty); eMN+qkvH  
Utility.log(sProperty); ~)wwX:;B_  
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InputStream input = httpConnection.getInputStream(); R2N^'  
//logResponseHead(httpConnection); 3V/_I<y  

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byte[] b = new byte[1024]; q8?
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int nRead; U
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) }O.LPQ0  
{ VR4E 2^  
nStartPos += fileAccessI.write(b,0,nRead);
>HcYVp~G  
//if(nThreadID == 1) 8>Du  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); X:G&5  
} [_ M6/  
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Utility.log("Thread " + nThreadID + " is over!"); '!
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bDownOver = true; ^V<J69ny|9  
//nPos = fileAccessI.write (b,0,nRead); 6%ZHP?  
} H_?;h-Y]  
catch(Exception e){e.printStackTrace ();} e{fZ}`=7y  
} W>Mse[6`c  
} \;-=ODC  
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//打印回应的头信息 #"Eks79s  
public void logResponseHead(HttpURLConnection con) r7Nu>[r5  
{ j6tP)f^tD  
for(int i=1;;i++) m\6SG' X  
{ =$b-xsmeG  
String header=con.getHeaderFieldKey(i); 09  
if(header!=null) H\)gE>  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); oMh~5 W  
Utility.log(header+" : "+con.getHeaderField(header)); 0\5M^:8i3  
else g|ql 5jW  
break; b A)b`1lI  
} *>e~_{F  
} |x d@M-ln  
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: cFF  
public void splitterStop() rD0k%-{{  
{ M MAA
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bStop = true; ?_VRfeztw  
} s8t f@H4r  
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} E x_L!9>!  
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/* Rr+qgt;f5  
**FileAccess.java =LXvlt'Q34  
*//文件访问(定位，写) `]K,'i{R  
package NetFox; ;c>>$lr  
import java.io.*; 6RH/V:YY  
=a?a@+  
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public class FileAccessI implements Serializable{ HR[Q ?rg  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 X!T|07#c  
RandomAccessFile oSavedFile; shM{Y9~O9&  
long nPos; =MMCf0  
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public FileAccessI() throws IOException 54=}GnZN  
{ ;xSRwSNDi(  
this("",0); (-bRj#  
} nc<qbN  
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public FileAccessI(String sName,long nPos) throws IOException BwJNi6,  
{ PPN q:,  
oSavedFile = new RandomAccessFile(sName,"rw"); \C|;F  
this.nPos = nPos; v-ThdE$G#  
oSavedFile.seek(nPos); ^[en3aQ  
} 6/|U  
c2/FHI0J;  
a ]>VZOet  
public synchronized int write(byte[] b,int nStart,int nLen) >/b^fAG  
{ <E"*)Oi  
int n = -1; lNHNL a>W  
try{ yHl@_rN sC  
oSavedFile.write(b,nStart,nLen); M6\7FP6G  
n = nLen; f](I.lm:  
} !0b

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catch(IOException e) ?4:rP@  
{ LxB&7  
e.printStackTrace (); E\w+kAAf  
} fzl=d_  
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return n; pXssh  
} Dft4isyt^  
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} /n(9&'H<  
-=}b;Kf-  
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/* Bgf=\7;5  
**SiteInfoBean.java mLJDxh'B  
*/ $>;a'f~  
package NetFox; $;y1Qiel  
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public class SiteInfoBean { Ex6o=D2  
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private String sSiteURL; //Site's URL N50fL  
private String sFilePath; //Saved File's Path E$w#+.QP  
private String sFileName; //Saved File's Name &T7cH>E'K^  
private int nSplitter; //Count of Splited Downloading File {ZG:M}ieN  
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(X*9w##x(  
public SiteInfoBean() ~,T+JX  
{//nSplitter的缺省值为5 Oohq9f#!  
//default value of nSplitter is 5 )qmFK .;%  
this("","","",5); goB;EWz  
} gd K*"U  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ^eobp.U  
{ |Hfl&3  
sSiteURL= sURL; =C#*!N73  
sFilePath = sPath; G&jZ\IV  
sFileName = sName; a/34WFC  
this.nSplitter = nSpiltter; 5.dl>,  
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} XwtAF3oz  
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public String getSSiteURL() h<)yJh  
{ )&Mq,@  
return sSiteURL; ]9s\_A9  
} 9Yn)t#G'`F  
y=#j`MH{>  
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public void setSSiteURL(String value) @*SA$9/l  
{ 2Q}7fht  
sSiteURL = value; z#RuwB+  
} 2qlIy  
{a. <`  
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public String getSFilePath() T~h.=5  
{ t?HF-zQ  
return sFilePath; #v+;:  
} FJ}gUs{m  
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$,@JYLC2  
public void setSFilePath(String value) <W2ZoqaV  
{ xdqK.Z%  
sFilePath = value; 7C?E z%a@  
} Tv1]v.  
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public String getSFileName() I )5<DZB9  
{ V,m3-=q  
return sFileName; K_Re}\D  
} j$mz3Yk  
0X#+#[W  
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public void setSFileName(String value) \OT6L'l],  
{ ]q&tQJ/Fa  
sFileName = value; ??j&i6sp  
} k/@Tr
:  
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=-5[Hn%  
public int getNSplitter() @i{]4rk lv  
{ KJX>DL 9\  
return nSplitter; \f<z*!,D$  
} ?^. Pt  
8 ip^]  
`H"vR:~{  
public void setNSplitter(int nCount) onib x^Fcd  
{ %0zS  
nSplitter = nCount; 'gCZ'edM  
} ~5T$8^K  
} ']h IfOD"r  
%i595Ij-]  
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/* +!><5  
**Utility.java op.d;lO@  
*/ ly=a>}F_  
package NetFox; 8O9Gs  
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public class Utility { {!r#f(?uT  

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public Utility() Z0W0uP;J  
{ 2LC w*eT{)  
#QS?s8IrW  
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} %{"dP%|w4}  
kIX)oD}c  
//线程睡眠 86qcf"?E  
public static void sleep(int nSecond) \OY}GR
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{ /?U!y?t&@  
try{ b`zET^F  
Thread.sleep(nSecond); {mf.!Xev
 
} ^e%k~B^  
catch(Exception e) x 'mF&^  
{ gH'3 dS!{  
e.printStackTrace (); Sc{Tq\t;%  
} (0}j]p'w  
} #D0 ~{H  
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//日志 x0ne8NDP  
public static void log(String sMsg) }1@E"6kF  
{ ^cn@?k((A  
System.err.println(sMsg); #a'r_K=ch)  
} sG1BNb_  
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public static void log(int sMsg) _#vGs:-x&  
{ ^)<w*iqBD  
System.err.println(sMsg); SBL+e]P  
} JqSr[q  
} 0 u2Ny&6w  
9(OAKUQ  
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/* p6Gcts?,  
**TestMethod.java ayeCi8
  
*/ XWXr0>!,?  
package NetFox; I=odMw7Hj  
7>&1nBh. f  
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public class TestMethod { $Elkhe]O %  
Qt~B#R. V  
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public TestMethod() IM]h*YV'  
{ ///xx/weblogic60b2_win.exe O8y9dX-2  
try{ C=[A
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ~1ps7[  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 73)Ll"(  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ZPvf-PqJl  
fileFetch.start(); Z/h|\SyJ  
} ONfyYM?  
catch(Exception e){e.printStackTrace ();} (!-;T  
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{G%3*=?,j  
} hIo0S8MOj$  
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public static void main(String[] args) I*(1.%:m  
{ H`gb}?9R  
new TestMethod(); 2rmNdvvrk  
} C5;wf3  
} bQj`g2eyM  
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