http断点续传简单实现（java)

/* _aevaWtEx  
**SiteFileFetch.java f;^ +q-Q  
*/ pFY*Y>6ar  
package NetFox; :@i+yN cV  
import java.io.*; ~'%d]s+q  
import java.net.*; G/p\MzDko  
# &.syD#  
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public class SiteFileFetch extends Thread { (|<S%
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SiteInfoBean siteInfoBean = null; //文件信息Bean Oq~{HJ{  
long[] nStartPos; //开始位置 Qw2`@P8W  
long[] nEndPos; //结束位置 )).=MTk  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 )&_bY~
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long nFileLength; //文件长度 
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boolean bFirst = true; //是否第一次取文件 B-N//ef}  
boolean bStop = false; //停止标志 9JP:wE~y  
File tmpFile; //文件下载的临时信息 > f X^NX  
DataOutputStream output; //输出到文件的输出流 Gt#r$.]W?o  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） bK%F_v3'  
public SiteFileFetch(SiteInfoBean bean) throws IOException #ae?#?/"  
{ N62;@Z\7  
siteInfoBean = bean; ]|g2V a~-  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); n{!{,s  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); qI9j=4s.  
if(tmpFile.exists ()) 6ioj!w<N  
{ Zzjx;SF  
bFirst = false; ;)FvTm'"\.  
read_nPos(); uSR%6=$  
} _MC',p&  
else Eh8GqFEM  
{ K>+ v" x  
nStartPos = new long[bean.getNSplitter()]; uuEvH<1  
nEndPos = new long[bean.getNSplitter()]; *d C|X  
} P?
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} 5%2~/ "  
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public void run()  Culv/  
{ >P j#?j*Y  
//获得文件长度 6<W^T9}v@/  
//分割文件 h>!h|Ma  
//实例FileSplitterFetch HE+'fQ!R  
//启动FileSplitterFetch线程 \2 DED  
//等待子线程返回 Ne+Rs+~4  
try{ #d %v=.1  
if(bFirst) OE(y$+L3_I  
{ D Z*c.|W  
nFileLength = getFileSize(); Vwp>:'Pu  
if(nFileLength == -1) y/S3ZJY  
{ ;g?PK5rB(  
System.err.println("File Length is not known!"); %T
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} F.y_H#h  
else if(nFileLength == -2)  P s>Y]  
{ RjVUm+<  
System.err.println("File is not access!"); ub8d]GZJ  
} R-zS7Jyox  
else ,Dv*<La`\  
{ \uHC9}0  
for(int i=0;i<nStartPos.length;i++) |Jx:#OM  
{ ltNI+G  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); v+x<X5u  
} z{3`nd,  
for(int i=0;i<nEndPos.length-1;i++) h$`m0-'  
{ OiAuL:D  
nEndPos = nStartPos[i+1]; !q$VnqFk
 
} &w^9#L  
nEndPos[nEndPos.length-1] = nFileLength; |e#W;q$v  
} eMdP4<u  
} -sv%A7i  
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//启动子线程 >uZc#Zt  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; k 76<CX  
for(int i=0;i<nStartPos.length;i++) CP9Q|'oJ  
{ UBW,Q+Q  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), y$fMMAN7  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), W3/] 2"0  
nStartPos,nEndPos,i); ^"<Bk<b(  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); DC).p'0VL  
fileSplitterFetch.start(); 2<UC^vZ  
} 6k@F?qHS  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ]/h$6mrL  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); '['%b  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", FUSe!f  
nEndPos = " + nFileLength); nL^7t7mp  
// fileSplitterFetch[nPos.length-1].start(); `%[m%Y9h  
4j0;okQWV'  
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//等待子线程结束 L %acsb}  
//int count = 0; mN{H^  
//是否结束while循环 `&x>2FJ  
boolean breakWhile = false; L:_{bE|TY  
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while(!bStop) ~1TT?H  
{ =W')jKe0  
write_nPos(); t|V5[
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Utility.sleep(500); ?i0u)<H  
breakWhile = true; eptw)S-j  
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for(int i=0;i<nStartPos.length;i++) < `;Mf>V  
{ [}Xw/@Uc;  
if(!fileSplitterFetch.bDownOver) Wx#l}nD  
{ ]Z UE !  
breakWhile = false; j@nK6`d+1  
break; %ho?KU2j  
} LR.]&(kyd  
} !_+FuF"@  
if(breakWhile) _)pOkS  
break; +Goh`!$Rj9  
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//count++; 4J'0k<5S  
//if(count>4) (ZF~   
// siteStop(); HrLws95'  
} `;G@qp:A  
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System.err.println("文件下载结束！"); C+!=C{@7di  
} Y[b08{/  
catch(Exception e){e.printStackTrace ();} .(p_YjIA  
} P;XA|`&  
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d$\n@}8eZp  
//获得文件长度 1M)8
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public long getFileSize() )X*_oH=  
{ f[NxqNn
 
int nFileLength = -1; G?~Yw'R^8  
try{ WUYU\J&q3  
URL url = new URL(siteInfoBean.getSSiteURL()); r
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Qg1kF^=  
httpConnection.setRequestProperty("User-Agent","NetFox"); '"%hX&]5  
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int responseCode=httpConnection.getResponseCode(); $5ea[nc  
if(responseCode>=400) d+h~4'ebv  
{ {LKW%G7  
processErrorCode(responseCode); GRj [2I7:  
return -2; //-2 represent access is error ]n1#8T&<*z  
} 8:I-?z;S  
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String sHeader; 9. FXbNYg  
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for(int i=1;;i++) W
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{ xG4 C 6s  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); \ D>!&  
//Utility.log(in.readLine()); x^`P[>  
sHeader=httpConnection.getHeaderFieldKey(i); LCIe1P2  
if(sHeader!=null) USgO`l\}4  
{ p+nB@fN/  
if(sHeader.equals("Content-Length")) B;iJ$gt]  
{ l:~ >P[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); }#Ji"e  
break; w?fq%-6f*  
} R%t6sbsNv  
} hE\gXb  
else (3x2^M8  
break; bjwl21;{  
} ]~3a~  
} Y2uy@j*N  
catch(IOException e){e.printStackTrace ();} /viBJ`-O  
catch(Exception e){e.printStackTrace ();} z6qx9x|Ij  
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Utility.log(nFileLength); |1!OwQax  
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return nFileLength; HN;f~EQT  
} -:!T@
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//保存下载信息（文件指针位置） /sB,)>X  
private void write_nPos() 2jQ?-/Q8#  
{ ?ODBW/{[G  
try{ ygV-Fv>PQ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); S[/D._5QD%  
output.writeInt(nStartPos.length); >"]t4]GVf  
for(int i=0;i<nStartPos.length;i++) cE,,9M@^  
{ 1X&scVw  
// output.writeLong(nPos); "Q.C1#W}.  
output.writeLong(fileSplitterFetch.nStartPos); rc{F17~vX  
output.writeLong(fileSplitterFetch.nEndPos); oB
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} bM W}.v!  
output.close(); ,0,& L  
} ?[5_/0L,=  
catch(IOException e){e.printStackTrace ();} up?S (.*B  
catch(Exception e){e.printStackTrace ();} FSZ :}Q  
} y>J6)F =  
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//读取保存的下载信息（文件指针位置） DQN"85AIZ  
private void read_nPos() w*Ze5j4@ \  
{ cn_KHz=  
try{ TDR#'i  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); D0gz ((  
int nCount = input.readInt(); do< N+iK  
nStartPos = new long[nCount]; Hg(nC*#/Q  
nEndPos = new long[nCount]; ]MMXpj,9h  
for(int i=0;i<nStartPos.length;i++) mFC9\   
{ <;Td8T;  
nStartPos = input.readLong(); ,UT :wpc^i  
nEndPos = input.readLong(); ~05(92bK  
} j{%'A  
input.close(); 8;,(D#p  
} V\%s)kq  
catch(IOException e){e.printStackTrace ();} \xk8+=/A  
catch(Exception e){e.printStackTrace ();} 3=lQZi<]%  
} cn$0^7?  
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private void processErrorCode(int nErrorCode) a/q8vP  
{ v`"BXSmp{  
System.err.println("Error Code : " + nErrorCode); u9}LvQh_6,  
} Uv:NY1(3!  
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//停止文件下载 =:^f6"p&Z  
public void siteStop() 2cJ3b 0Xx  
{ N!af1zj  
bStop = true; iS8yJRy  
for(int i=0;i<nStartPos.length;i++) u,S}4p&l  
fileSplitterFetch.splitterStop(); G:PcV_ihx  
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} z 2Ao6*%  
} XV<{tqa  
//负责部分文件的抓取 } qr ,  
**FileSplitterFetch.java IqjH  
*/ G]>P!]  
package NetFox; 5AAPtZ\lH  
<K~mg<ff$  

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import java.io.*; PKNpR  
import java.net.*; Si[xyG6=  
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public class FileSplitterFetch extends Thread { ^: V6=  
(qy82F-|2  
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String sURL; //File URL l`<u\],  
long nStartPos; //File Snippet Start Position 0o&c8?@j  
long nEndPos; //File Snippet End Position - z"D_5  
int nThreadID; //Thread's ID l*4_  
boolean bDownOver = false; //Downing is over CEb al\R  
boolean bStop = false; //Stop identical 6%UhP;(  
FileAccessI fileAccessI = null; //File Access interface I/w=!Ih  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 0VlB7oF  
{ y{uN+QS  
this.sURL = sURL; vEb_z[gd  
this.nStartPos = nStart; 9|LV x3]  
this.nEndPos = nEnd; 2sqNTuO6,|  
nThreadID = id; gPM<LO`;i  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 )XL}u4X  
} @D&}ZV=J  
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public void run() Ft$tL;  
{ ;Quk
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while(nStartPos < nEndPos && !bStop) y@Ga9bI7  
{ YumHECej  
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try{ _,9/g^<  
URL url = new URL(sURL); 6`
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); srfM"Lb'  
httpConnection.setRequestProperty("User-Agent","NetFox"); 3eS *U`_  
String sProperty = "bytes="+nStartPos+"-"; 1Igo9rv  
httpConnection.setRequestProperty("RANGE",sProperty); =L?(mNHT  
Utility.log(sProperty); <gc\,P<ru  
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InputStream input = httpConnection.getInputStream(); cv/  
//logResponseHead(httpConnection); k'$
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byte[] b = new byte[1024]; SPK% '
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int nRead; )\r;|DN  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) d|(@#*{T]  
{ -&\?Q_6  
nStartPos += fileAccessI.write(b,0,nRead); a8!/
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//if(nThreadID == 1) N=P+b%%:Z  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); F`\7&'I  
} ZI'Mr:z4  
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Utility.log("Thread " + nThreadID + " is over!"); ^l"  
bDownOver = true; {:r8X  
//nPos = fileAccessI.write (b,0,nRead); c'r7sI%Yi  
} qdeS*rp\  
catch(Exception e){e.printStackTrace ();} -P>f2It  
} ;F!wyTF>}  
} 4
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R@)L@M)u;  
//打印回应的头信息 Vr=c06a2  
public void logResponseHead(HttpURLConnection con) U[ $A=e?\Y  
{ N [iv.B  
for(int i=1;;i++) ,
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{ qhiO( !jK  
String header=con.getHeaderFieldKey(i); OAiip,  
if(header!=null) g0B
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); s&7,gWy}BE  
Utility.log(header+" : "+con.getHeaderField(header)); }6V` U9^g  
else tu6Q7CjW8  
break; oAgO3x   
} f}1R,N_fC  
} +u:Q+PkM  
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public void splitterStop() L:g!f  
{ ]M;aVw<!  
bStop = true; tzeS D C  
} aN5w  
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} ITu6m<V  
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/* . !|3a  
**FileAccess.java ,\BGxGNAmV  
*//文件访问(定位，写) $m;rOKVU  
package NetFox; KF[P /cFI  
import java.io.*; MH>CCT  
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public class FileAccessI implements Serializable{ dm&vLQVS  
7]~65@%R-&  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 )"IBw0]  
RandomAccessFile oSavedFile; pv2u.qg5z  
long nPos; mGmkeD'  
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public FileAccessI() throws IOException 8W|qm;J98  
{ |lijnfp  
this("",0); : _>/Yd7-&  
} b'N(eka  
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public FileAccessI(String sName,long nPos) throws IOException 'o#ve72z1  
{ D#T1~r4  
oSavedFile = new RandomAccessFile(sName,"rw"); P2S$Dk_<\X  
this.nPos = nPos; av&4:O!  
oSavedFile.seek(nPos); K0i[D"
 
} D4x~Vk%H  
x*A_1_A  
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public synchronized int write(byte[] b,int nStart,int nLen) 8tM40/U$  
{ DJv;ed%x  
int n = -1; 2U-F}Z  
try{ .I@jt?6X  
oSavedFile.write(b,nStart,nLen); Dwq}O  
n = nLen; e)[>E\u_  
} j zaC  
catch(IOException e) V(%L}0[]  
{ v}v! hs Q  
e.printStackTrace (); /\S1p3EW*  
} 4&Uq\,nx  
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return n; Khbkv  
} ab1qcQ<  
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} d85\GEF9i  
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/* %d5;JEgA:g  
**SiteInfoBean.java LeA=*+zP[  
*/
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package NetFox; ?G[<~J3-E  
f((pRP  
\(PC#H%  
public class SiteInfoBean { =dyApR:'  
tp='PG.6  
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private String sSiteURL; //Site's URL f&w8o5=|I  
private String sFilePath; //Saved File's Path w7H.&7rF  
private String sFileName; //Saved File's Name ZI q!ee  
private int nSplitter; //Count of Splited Downloading File kMGK8y  
&95iGL28Q  
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public SiteInfoBean() sbZ$h <  
{//nSplitter的缺省值为5 .!ThqYo  
//default value of nSplitter is 5 { jnQoxN  
this("","","",5); *^XfEO  
} "x.|'  
LLn,pI2fL{  
$'I+] ;  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) E$-u:Z<-  
{ !$"DD[~\  
sSiteURL= sURL; `.f {V  
sFilePath = sPath; [TAW68f'  
sFileName = sName; ,O@xv
 
this.nSplitter = nSpiltter; =_%i5]89P  
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} 
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public String getSSiteURL() qc}r.'p  
{ x&6SjlDb$K  
return sSiteURL; (vCMff/ Y1  
} B
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-9XB.)\#  
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public void setSSiteURL(String value) UXz0HRRS0  
{ B!|<<;Da6  
sSiteURL = value; ~c>*3*  
} -jc8ku3*  
;}!hgyq  
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public String getSFilePath() =Rl?. +uE  
{ ), >jBYMJ  
return sFilePath; M+<xX)   
} d,fX3  
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public void setSFilePath(String value) lsV9-)yyl  
{ ?dJ-g~  
sFilePath = value; {*VCR  
} )J?Nfi%  
~n:dHK`  
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public String getSFileName() -@49Zh2'  
{ X<\y%2B|l  
return sFileName; 4\)
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} LRO'o{4$E  
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public void setSFileName(String value) W+3ZuAP\n  
{ ,Vz 1l_7  
sFileName = value; MHN?ZHC)  
} 74VN3m  
3[kY:5-  
KX e/i~A
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public int getNSplitter() l0Myem v?z  
{ 8}m bfuo1  
return nSplitter; :3k&[W*  
} o8+ZgXct  
t?NB#/#%x  
0GR\iw$[J  
public void setNSplitter(int nCount) o9dqHm  
{ z4f\0uQ
 
nSplitter = nCount; [#y/`  
} AtRu)v6r  
} ZCJOh8  
3.q%?S}*  
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/* 14TA( v]T  
**Utility.java ^dB~#A1  
*/ [KA&KI^hF  
package NetFox; 7 jq?zS|  
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% AqUVt9}  
public class Utility { @5n!t1(  
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public Utility() %Z@+K_X9x  
{ /
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Ha l,%W~e  
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} !8q+W`{  
)clSW  
//线程睡眠 ;[%_sVIy  
public static void sleep(int nSecond) YfBb=rN2s  
{ 0-H!\IB  
try{ _3UH"9g{  
Thread.sleep(nSecond); z;:c_y!f  
} }q1@[ aE  
catch(Exception e) >C"f'!oM,j  
{ p F\~T>  
e.printStackTrace (); )ndcBwQc"  
} 
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} 0HUSN_3F  
%c%0pGn8-  
//日志 =[8EQdR  
public static void log(String sMsg) `Tt}:9/3  
{ :'aT4  
System.err.println(sMsg); .Ap-<FB  
} 5~T`R~Uqb  
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public static void log(int sMsg) 70,V>=aJ  
{ Dm=t`_DL8  
System.err.println(sMsg); ea3;1-b:  
} Ad)Po  
} 9] /xAsD  
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/* |cpBoU  
**TestMethod.java qd*3| O^  
*/ cjzhuH/y  
package NetFox; zx"'WM*  
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public class TestMethod { .'o<.\R8  
&V5[Zj|]  
f}q4~NPn-  
public TestMethod() ,]?Xf>  
{ ///xx/weblogic60b2_win.exe H.EgL@;mb  
try{ &6fNPD(|  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); m+p}Qi8i)  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); y6.}h9~  
SiteFileFetch fileFetch = new SiteFileFetch(bean); K;jV"R<9  
fileFetch.start(); WF0%zxg]  
} CZB!vh0  
catch(Exception e){e.printStackTrace ();} Qs2E>C  
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} E"!I[  
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public static void main(String[] args) )i8Hdtn  
{ ;AV[bjRE\  
new TestMethod(); fE"Q:K6r2  
} N9LBji;nH  
} j-wSsjLk  
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